refactor: collapse fp8 recipe hierarchy and state property layers

- Merge DelayedScaling/DynamicScaling and the abstract FP8Recipe base into one FP8Recipe dataclass with a dynamic flag; dispatch now reads cfg.recipe.dynamic instead of isinstance checks
- Drop the _ActiveOrDefault descriptor and the FP8State property views; the persistent defaults are plain default_* attributes and get_weight_meta takes the active recipe explicitly
- Convert FP8TensorMeta to a NamedTuple of the three per-operand rings
- Update tests to the new API; the autocast context test now asserts _active_config push/restore directly

.dockerignore

@@ -4,6 +4,8 @@
 # Allow necessary files
 !astrai/
 !scripts/
-!assets/
+!docs/
+!csrc/
+!setup.py
 !pyproject.toml
 !README.md

.github/workflows/release.yml

@@ -23,33 +23,46 @@ jobs:
         with:
           name: pure-wheel
           path: dist/*.whl
+          if-no-files-found: error
 
   build-cuda-linux:
-    name: Build CUDA wheel (Linux)
+    name: Build CUDA wheel (Linux, ${{ matrix.cuda_tag }})
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - cuda_tag: "cu128"
+            cuda_ver: "12.8.0"
+          - cuda_tag: "cu130"
+            cuda_ver: "13.0.0"
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5
         with:
           python-version: "3.12"
 
-      - name: Install torch (CUDA 12.8)
+      - name: Install torch (${{ matrix.cuda_tag }})
         run: |
-          pip install torch --index-url https://download.pytorch.org/whl/cu128
+          pip install torch --index-url https://download.pytorch.org/whl/${{ matrix.cuda_tag }}
 
-      - name: Setup CUDA
+      - name: Setup CUDA (${{ matrix.cuda_ver }})
         uses: Jimver/cuda-toolkit@v0.2.35
         with:
-          cuda: "12.8.0"
+          cuda: "${{ matrix.cuda_ver }}"
 
       - name: Build wheel (with CUDA kernels)
         run: |
           CSRC_KERNELS=true pip wheel . --no-deps --no-build-isolation -w dist/
+          for f in dist/*.whl; do
+            mv "$f" "dist/$(basename "$f" .whl)+${{ matrix.cuda_tag }}.whl"
+          done
 
       - uses: actions/upload-artifact@v4
         with:
-          name: cuda-wheel-linux
+          name: cuda-wheel-linux-${{ matrix.cuda_tag }}
           path: dist/*.whl
+          if-no-files-found: error
 
   release:
     name: Attach wheels to release
@@ -58,14 +71,33 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/download-artifact@v4
+      - name: Download pure-Python wheel
+        uses: actions/download-artifact@v4
         with:
-          pattern: "*-wheel"
+          name: pure-wheel
+          path: release-assets/pure
+
+      - name: Download CUDA wheels (all variants)
+        uses: actions/download-artifact@v4
+        with:
+          pattern: cuda-wheel-linux-*
           merge-multiple: true
+          path: release-assets/cuda
+
+      - name: Verify release assets
+        shell: bash
+        run: |
+          set -euo pipefail
+          pure_wheels=(release-assets/pure/*.whl)
+          cuda_wheels=(release-assets/cuda/*.whl)
+          test "${#pure_wheels[@]}" -eq 1
+          test "${#cuda_wheels[@]}" -ge 1
 
       - name: Create release & upload assets
         uses: softprops/action-gh-release@v2
         with:
-          files: ./*.whl
+          files: |
+            release-assets/pure/*.whl
+            release-assets/cuda/*.whl
           tag_name: ${{ github.ref_name }}
           generate_release_notes: true

.gitignore

@@ -9,6 +9,7 @@
 !scripts/**/*.py
 !tests/**/*.py
 !csrc/**/*.py
+!csrc/CMakeLists.txt
 
 !csrc/**/*.cu
 !csrc/**/*.h
@@ -24,7 +25,7 @@
 !/.dockerignore
 !/Dockerfile
 !/docker-compose.yml
-!/assets/**
+!/docs/**
 !/CONTRIBUTING.md
 !/LICENSE
 !/pyproject.toml

CONTRIBUTING.md

@@ -20,9 +20,6 @@ Run the following checks **in order** — CI will reject if any fail.
 ruff format .
 ```
 
-> **Note**: `ruff format` may rename parameters (e.g. `mask` → `attn_mask`).  
-> Always review the diff after formatting.
-
 ### 2. Import sorting
 
 ```bash
@@ -42,22 +39,28 @@ ruff format .    # re-format after fix
 python -u -m pytest tests/ -v
 ```
 
-> Failed tests may leave orphan tempdirs under `%TEMP%`. Clean them manually if needed.
+> Failed tests may leave orphan tempdirs under the system temp directory
+> (`$TMPDIR` on Linux/macOS, `%TEMP%` on Windows). Clean them manually if needed.
 
-### 4. (Optional) Full pre-commit check
+### 4. (Optional) Full pre-commit check script
 
-If you have Git Bash available:
+If you have `bash` available (Git Bash on Windows works too):
 
 ```bash
 bash scripts/pre_commit.sh
 ```
 
-This runs format check, import sort check, and tests in one go.
+The script installs development dependencies by default, then runs the format
+check, import sort check, and tests. If dependencies are already installed, use:
+
+```bash
+bash scripts/pre_commit.sh --skip-deps
+```
 
 ## Commit Style
 
 ```
-fix/feat/chore/docs/refactor/perf/test/style/ci/build/revert : short description (~50 chars)
+type: short description (~50 chars)
 
 - bullet point body (each ~60 chars)
 ```
@@ -73,7 +76,7 @@ fix/feat/chore/docs/refactor/perf/test/style/ci/build/revert : short description
 |---------|-------|-----|
 | `ruff check --select I` fails | Wrong import order | `ruff check . --select I --fix .` then `ruff format .` |
 | `ruff format` changed many files | Not formatted before commit | Review diff carefully before staging |
-| Pre-commit hook rejects | Tests or lint failed | Fix individually, do not `--no-verify` |
+| Pre-commit check script fails | Dependency install, tests, or lint failed | Fix the failing step; use `--skip-deps` only when dependencies are already installed |
 | Tests fail with tempdir left | Test crash | Clean `%TEMP%` manually |
 
 ## Submitting Changes
@@ -93,7 +96,7 @@ fix/feat/chore/docs/refactor/perf/test/style/ci/build/revert : short description
 
 ## License
 
-By contributing, you agree that your contributions will be licensed under the [GPL-3.0 License](LICENSE).
+By contributing, you agree that your contributions will be licensed under the [Apache-2.0 License](LICENSE).
 
 ---
 

Dockerfile

@@ -1,8 +1,16 @@
 # AstrAI Dockerfile - Multi-stage Build (Optimized)
+#
+# CUDA version selection:
+#   docker build -t astrai .
+#   docker build -t astrai --build-arg CUDA_TAG=cu128 .
+#   docker build -t astrai --build-arg CUDA_TAG=cu130 .
+# Default: cu128
 
 # Build stage - use base image with minimal build tools
 FROM ubuntu:24.04 AS builder
 
+ARG CUDA_TAG=cu128
+
 WORKDIR /app
 
 # Install Python 3.12 and minimal build dependencies
@@ -20,10 +28,12 @@ ENV PATH="/opt/venv/bin:$PATH"
 
 # Copy source code and install (deps read from pyproject.toml)
 COPY astrai/ ./astrai/
+COPY csrc/ ./csrc/
+COPY setup.py .
 COPY pyproject.toml .
 RUN pip install --no-cache-dir --upgrade pip \
     && pip install --no-cache-dir . \
-    --extra-index-url https://download.pytorch.org/whl/cu128
+    --extra-index-url "https://download.pytorch.org/whl/${CUDA_TAG}"
 
 # Production stage
 FROM ubuntu:24.04 AS production
@@ -43,12 +53,21 @@ ENV PATH="/opt/venv/bin:$PATH"
 # Copy application code
 COPY astrai/ ./astrai/
 COPY scripts/ ./scripts/
-COPY assets/ ./assets/
+COPY docs/ ./docs/
 COPY pyproject.toml .
 COPY README.md .
 
-# Create non-root user
-RUN useradd -m astrai && chown -R astrai:astrai /app
+# Create non-root user matching the host uid/gid (passed via build args).
+# ubuntu:24.04 ships a default 'ubuntu' user/group at uid/gid 1000, so remove
+# it first to free those ids before creating astrai.
+ARG USER_UID=1000
+ARG USER_GID=1000
+RUN userdel -r ubuntu 2>/dev/null || true \
+    && groupdel ubuntu 2>/dev/null || true \
+    && groupadd -g "${USER_GID}" astrai \
+    && useradd -m -u "${USER_UID}" -g astrai astrai \
+    && chown -R astrai:astrai /app
+ENV HOME=/home/astrai
 USER astrai
 
 ENV PYTHONUNBUFFERED=1 \

LICENSE

@@ -1,674 +1,201 @@
-                    GNU GENERAL PUBLIC LICENSE
-                       Version 3, 29 June 2007
-
- Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
-                            Preamble
-
-  The GNU General Public License is a free, copyleft license for
-software and other kinds of works.
-
-  The licenses for most software and other practical works are designed
-to take away your freedom to share and change the works.  By contrast,
-the GNU General Public License is intended to guarantee your freedom to
-share and change all versions of a program--to make sure it remains free
-software for all its users.  We, the Free Software Foundation, use the
-GNU General Public License for most of our software; it applies also to
-any other work released this way by its authors.  You can apply it to
-your programs, too.
-
-  When we speak of free software, we are referring to freedom, not
-price.  Our General Public Licenses are designed to make sure that you
-have the freedom to distribute copies of free software (and charge for
-them if you wish), that you receive source code or can get it if you
-want it, that you can change the software or use pieces of it in new
-free programs, and that you know you can do these things.
-
-  To protect your rights, we need to prevent others from denying you
-these rights or asking you to surrender the rights.  Therefore, you have
-certain responsibilities if you distribute copies of the software, or if
-you modify it: responsibilities to respect the freedom of others.
-
-  For example, if you distribute copies of such a program, whether
-gratis or for a fee, you must pass on to the recipients the same
-freedoms that you received.  You must make sure that they, too, receive
-or can get the source code.  And you must show them these terms so they
-know their rights.
-
-  Developers that use the GNU GPL protect your rights with two steps:
-(1) assert copyright on the software, and (2) offer you this License
-giving you legal permission to copy, distribute and/or modify it.
-
-  For the developers' and authors' protection, the GPL clearly explains
-that there is no warranty for this free software.  For both users' and
-authors' sake, the GPL requires that modified versions be marked as
-changed, so that their problems will not be attributed erroneously to
-authors of previous versions.
-
-  Some devices are designed to deny users access to install or run
-modified versions of the software inside them, although the manufacturer
-can do so.  This is fundamentally incompatible with the aim of
-protecting users' freedom to change the software.  The systematic
-pattern of such abuse occurs in the area of products for individuals to
-use, which is precisely where it is most unacceptable.  Therefore, we
-have designed this version of the GPL to prohibit the practice for those
-products.  If such problems arise substantially in other domains, we
-stand ready to extend this provision to those domains in future versions
-of the GPL, as needed to protect the freedom of users.
-
-  Finally, every program is threatened constantly by software patents.
-States should not allow patents to restrict development and use of
-software on general-purpose computers, but in those that do, we wish to
-avoid the special danger that patents applied to a free program could
-make it effectively proprietary.  To prevent this, the GPL assures that
-patents cannot be used to render the program non-free.
-
-  The precise terms and conditions for copying, distribution and
-modification follow.
-
-                       TERMS AND CONDITIONS
-
-  0. Definitions.
-
-  "This License" refers to version 3 of the GNU General Public License.
-
-  "Copyright" also means copyright-like laws that apply to other kinds of
-works, such as semiconductor masks.
-
-  "The Program" refers to any copyrightable work licensed under this
-License.  Each licensee is addressed as "you".  "Licensees" and
-"recipients" may be individuals or organizations.
-
-  To "modify" a work means to copy from or adapt all or part of the work
-in a fashion requiring copyright permission, other than the making of an
-exact copy.  The resulting work is called a "modified version" of the
-earlier work or a work "based on" the earlier work.
-
-  A "covered work" means either the unmodified Program or a work based
-on the Program.
-
-  To "propagate" a work means to do anything with it that, without
-permission, would make you directly or secondarily liable for
-infringement under applicable copyright law, except executing it on a
-computer or modifying a private copy.  Propagation includes copying,
-distribution (with or without modification), making available to the
-public, and in some countries other activities as well.
-
-  To "convey" a work means any kind of propagation that enables other
-parties to make or receive copies.  Mere interaction with a user through
-a computer network, with no transfer of a copy, is not conveying.
-
-  An interactive user interface displays "Appropriate Legal Notices"
-to the extent that it includes a convenient and prominently visible
-feature that (1) displays an appropriate copyright notice, and (2)
-tells the user that there is no warranty for the work (except to the
-extent that warranties are provided), that licensees may convey the
-work under this License, and how to view a copy of this License.  If
-the interface presents a list of user commands or options, such as a
-menu, a prominent item in the list meets this criterion.
-
-  1. Source Code.
-
-  The "source code" for a work means the preferred form of the work
-for making modifications to it.  "Object code" means any non-source
-form of a work.
-
-  A "Standard Interface" means an interface that either is an official
-standard defined by a recognized standards body, or, in the case of
-interfaces specified for a particular programming language, one that
-is widely used among developers working in that language.
-
-  The "System Libraries" of an executable work include anything, other
-than the work as a whole, that (a) is included in the normal form of
-packaging a Major Component, but which is not part of that Major
-Component, and (b) serves only to enable use of the work with that
-Major Component, or to implement a Standard Interface for which an
-implementation is available to the public in source code form.  A
-"Major Component", in this context, means a major essential component
-(kernel, window system, and so on) of the specific operating system
-(if any) on which the executable work runs, or a compiler used to
-produce the work, or an object code interpreter used to run it.
-
-  The "Corresponding Source" for a work in object code form means all
-the source code needed to generate, install, and (for an executable
-work) run the object code and to modify the work, including scripts to
-control those activities.  However, it does not include the work's
-System Libraries, or general-purpose tools or generally available free
-programs which are used unmodified in performing those activities but
-which are not part of the work.  For example, Corresponding Source
-includes interface definition files associated with source files for
-the work, and the source code for shared libraries and dynamically
-linked subprograms that the work is specifically designed to require,
-such as by intimate data communication or control flow between those
-subprograms and other parts of the work.
-
-  The Corresponding Source need not include anything that users
-can regenerate automatically from other parts of the Corresponding
-Source.
-
-  The Corresponding Source for a work in source code form is that
-same work.
-
-  2. Basic Permissions.
-
-  All rights granted under this License are granted for the term of
-copyright on the Program, and are irrevocable provided the stated
-conditions are met.  This License explicitly affirms your unlimited
-permission to run the unmodified Program.  The output from running a
-covered work is covered by this License only if the output, given its
-content, constitutes a covered work.  This License acknowledges your
-rights of fair use or other equivalent, as provided by copyright law.
-
-  You may make, run and propagate covered works that you do not
-convey, without conditions so long as your license otherwise remains
-in force.  You may convey covered works to others for the sole purpose
-of having them make modifications exclusively for you, or provide you
-with facilities for running those works, provided that you comply with
-the terms of this License in conveying all material for which you do
-not control copyright.  Those thus making or running the covered works
-for you must do so exclusively on your behalf, under your direction
-and control, on terms that prohibit them from making any copies of
-your copyrighted material outside their relationship with you.
-
-  Conveying under any other circumstances is permitted solely under
-the conditions stated below.  Sublicensing is not allowed; section 10
-makes it unnecessary.
-
-  3. Protecting Users' Legal Rights From Anti-Circumvention Law.
-
-  No covered work shall be deemed part of an effective technological
-measure under any applicable law fulfilling obligations under article
-11 of the WIPO copyright treaty adopted on 20 December 1996, or
-similar laws prohibiting or restricting circumvention of such
-measures.
-
-  When you convey a covered work, you waive any legal power to forbid
-circumvention of technological measures to the extent such circumvention
-is effected by exercising rights under this License with respect to
-the covered work, and you disclaim any intention to limit operation or
-modification of the work as a means of enforcing, against the work's
-users, your or third parties' legal rights to forbid circumvention of
-technological measures.
-
-  4. Conveying Verbatim Copies.
-
-  You may convey verbatim copies of the Program's source code as you
-receive it, in any medium, provided that you conspicuously and
-appropriately publish on each copy an appropriate copyright notice;
-keep intact all notices stating that this License and any
-non-permissive terms added in accord with section 7 apply to the code;
-keep intact all notices of the absence of any warranty; and give all
-recipients a copy of this License along with the Program.
-
-  You may charge any price or no price for each copy that you convey,
-and you may offer support or warranty protection for a fee.
-
-  5. Conveying Modified Source Versions.
-
-  You may convey a work based on the Program, or the modifications to
-produce it from the Program, in the form of source code under the
-terms of section 4, provided that you also meet all of these conditions:
-
-    a) The work must carry prominent notices stating that you modified
-    it, and giving a relevant date.
-
-    b) The work must carry prominent notices stating that it is
-    released under this License and any conditions added under section
-    7.  This requirement modifies the requirement in section 4 to
-    "keep intact all notices".
-
-    c) You must license the entire work, as a whole, under this
-    License to anyone who comes into possession of a copy.  This
-    License will therefore apply, along with any applicable section 7
-    additional terms, to the whole of the work, and all its parts,
-    regardless of how they are packaged.  This License gives no
-    permission to license the work in any other way, but it does not
-    invalidate such permission if you have separately received it.
-
-    d) If the work has interactive user interfaces, each must display
-    Appropriate Legal Notices; however, if the Program has interactive
-    interfaces that do not display Appropriate Legal Notices, your
-    work need not make them do so.
-
-  A compilation of a covered work with other separate and independent
-works, which are not by their nature extensions of the covered work,
-and which are not combined with it such as to form a larger program,
-in or on a volume of a storage or distribution medium, is called an
-"aggregate" if the compilation and its resulting copyright are not
-used to limit the access or legal rights of the compilation's users
-beyond what the individual works permit.  Inclusion of a covered work
-in an aggregate does not cause this License to apply to the other
-parts of the aggregate.
-
-  6. Conveying Non-Source Forms.
-
-  You may convey a covered work in object code form under the terms
-of sections 4 and 5, provided that you also convey the
-machine-readable Corresponding Source under the terms of this License,
-in one of these ways:
-
-    a) Convey the object code in, or embodied in, a physical product
-    (including a physical distribution medium), accompanied by the
-    Corresponding Source fixed on a durable physical medium
-    customarily used for software interchange.
-
-    b) Convey the object code in, or embodied in, a physical product
-    (including a physical distribution medium), accompanied by a
-    written offer, valid for at least three years and valid for as
-    long as you offer spare parts or customer support for that product
-    model, to give anyone who possesses the object code either (1) a
-    copy of the Corresponding Source for all the software in the
-    product that is covered by this License, on a durable physical
-    medium customarily used for software interchange, for a price no
-    more than your reasonable cost of physically performing this
-    conveying of source, or (2) access to copy the
-    Corresponding Source from a network server at no charge.
-
-    c) Convey individual copies of the object code with a copy of the
-    written offer to provide the Corresponding Source.  This
-    alternative is allowed only occasionally and noncommercially, and
-    only if you received the object code with such an offer, in accord
-    with subsection 6b.
-
-    d) Convey the object code by offering access from a designated
-    place (gratis or for a charge), and offer equivalent access to the
-    Corresponding Source in the same way through the same place at no
-    further charge.  You need not require recipients to copy the
-    Corresponding Source along with the object code.  If the place to
-    copy the object code is a network server, the Corresponding Source
-    may be on a different server (operated by you or a third party)
-    that supports equivalent copying facilities, provided you maintain
-    clear directions next to the object code saying where to find the
-    Corresponding Source.  Regardless of what server hosts the
-    Corresponding Source, you remain obligated to ensure that it is
-    available for as long as needed to satisfy these requirements.
-
-    e) Convey the object code using peer-to-peer transmission, provided
-    you inform other peers where the object code and Corresponding
-    Source of the work are being offered to the general public at no
-    charge under subsection 6d.
-
-  A separable portion of the object code, whose source code is excluded
-from the Corresponding Source as a System Library, need not be
-included in conveying the object code work.
-
-  A "User Product" is either (1) a "consumer product", which means any
-tangible personal property which is normally used for personal, family,
-or household purposes, or (2) anything designed or sold for incorporation
-into a dwelling.  In determining whether a product is a consumer product,
-doubtful cases shall be resolved in favor of coverage.  For a particular
-product received by a particular user, "normally used" refers to a
-typical or common use of that class of product, regardless of the status
-of the particular user or of the way in which the particular user
-actually uses, or expects or is expected to use, the product.  A product
-is a consumer product regardless of whether the product has substantial
-commercial, industrial or non-consumer uses, unless such uses represent
-the only significant mode of use of the product.
-
-  "Installation Information" for a User Product means any methods,
-procedures, authorization keys, or other information required to install
-and execute modified versions of a covered work in that User Product from
-a modified version of its Corresponding Source.  The information must
-suffice to ensure that the continued functioning of the modified object
-code is in no case prevented or interfered with solely because
-modification has been made.
-
-  If you convey an object code work under this section in, or with, or
-specifically for use in, a User Product, and the conveying occurs as
-part of a transaction in which the right of possession and use of the
-User Product is transferred to the recipient in perpetuity or for a
-fixed term (regardless of how the transaction is characterized), the
-Corresponding Source conveyed under this section must be accompanied
-by the Installation Information.  But this requirement does not apply
-if neither you nor any third party retains the ability to install
-modified object code on the User Product (for example, the work has
-been installed in ROM).
-
-  The requirement to provide Installation Information does not include a
-requirement to continue to provide support service, warranty, or updates
-for a work that has been modified or installed by the recipient, or for
-the User Product in which it has been modified or installed.  Access to a
-network may be denied when the modification itself materially and
-adversely affects the operation of the network or violates the rules and
-protocols for communication across the network.
-
-  Corresponding Source conveyed, and Installation Information provided,
-in accord with this section must be in a format that is publicly
-documented (and with an implementation available to the public in
-source code form), and must require no special password or key for
-unpacking, reading or copying.
-
-  7. Additional Terms.
-
-  "Additional permissions" are terms that supplement the terms of this
-License by making exceptions from one or more of its conditions.
-Additional permissions that are applicable to the entire Program shall
-be treated as though they were included in this License, to the extent
-that they are valid under applicable law.  If additional permissions
-apply only to part of the Program, that part may be used separately
-under those permissions, but the entire Program remains governed by
-this License without regard to the additional permissions.
-
-  When you convey a copy of a covered work, you may at your option
-remove any additional permissions from that copy, or from any part of
-it.  (Additional permissions may be written to require their own
-removal in certain cases when you modify the work.)  You may place
-additional permissions on material, added by you to a covered work,
-for which you have or can give appropriate copyright permission.
-
-  Notwithstanding any other provision of this License, for material you
-add to a covered work, you may (if authorized by the copyright holders of
-that material) supplement the terms of this License with terms:
-
-    a) Disclaiming warranty or limiting liability differently from the
-    terms of sections 15 and 16 of this License; or
-
-    b) Requiring preservation of specified reasonable legal notices or
-    author attributions in that material or in the Appropriate Legal
-    Notices displayed by works containing it; or
-
-    c) Prohibiting misrepresentation of the origin of that material, or
-    requiring that modified versions of such material be marked in
-    reasonable ways as different from the original version; or
-
-    d) Limiting the use for publicity purposes of names of licensors or
-    authors of the material; or
-
-    e) Declining to grant rights under trademark law for use of some
-    trade names, trademarks, or service marks; or
-
-    f) Requiring indemnification of licensors and authors of that
-    material by anyone who conveys the material (or modified versions of
-    it) with contractual assumptions of liability to the recipient, for
-    any liability that these contractual assumptions directly impose on
-    those licensors and authors.
-
-  All other non-permissive additional terms are considered "further
-restrictions" within the meaning of section 10.  If the Program as you
-received it, or any part of it, contains a notice stating that it is
-governed by this License along with a term that is a further
-restriction, you may remove that term.  If a license document contains
-a further restriction but permits relicensing or conveying under this
-License, you may add to a covered work material governed by the terms
-of that license document, provided that the further restriction does
-not survive such relicensing or conveying.
-
-  If you add terms to a covered work in accord with this section, you
-must place, in the relevant source files, a statement of the
-additional terms that apply to those files, or a notice indicating
-where to find the applicable terms.
-
-  Additional terms, permissive or non-permissive, may be stated in the
-form of a separately written license, or stated as exceptions;
-the above requirements apply either way.
-
-  8. Termination.
-
-  You may not propagate or modify a covered work except as expressly
-provided under this License.  Any attempt otherwise to propagate or
-modify it is void, and will automatically terminate your rights under
-this License (including any patent licenses granted under the third
-paragraph of section 11).
-
-  However, if you cease all violation of this License, then your
-license from a particular copyright holder is reinstated (a)
-provisionally, unless and until the copyright holder explicitly and
-finally terminates your license, and (b) permanently, if the copyright
-holder fails to notify you of the violation by some reasonable means
-prior to 60 days after the cessation.
-
-  Moreover, your license from a particular copyright holder is
-reinstated permanently if the copyright holder notifies you of the
-violation by some reasonable means, this is the first time you have
-received notice of violation of this License (for any work) from that
-copyright holder, and you cure the violation prior to 30 days after
-your receipt of the notice.
-
-  Termination of your rights under this section does not terminate the
-licenses of parties who have received copies or rights from you under
-this License.  If your rights have been terminated and not permanently
-reinstated, you do not qualify to receive new licenses for the same
-material under section 10.
-
-  9. Acceptance Not Required for Having Copies.
-
-  You are not required to accept this License in order to receive or
-run a copy of the Program.  Ancillary propagation of a covered work
-occurring solely as a consequence of using peer-to-peer transmission
-to receive a copy likewise does not require acceptance.  However,
-nothing other than this License grants you permission to propagate or
-modify any covered work.  These actions infringe copyright if you do
-not accept this License.  Therefore, by modifying or propagating a
-covered work, you indicate your acceptance of this License to do so.
-
-  10. Automatic Licensing of Downstream Recipients.
-
-  Each time you convey a covered work, the recipient automatically
-receives a license from the original licensors, to run, modify and
-propagate that work, subject to this License.  You are not responsible
-for enforcing compliance by third parties with this License.
-
-  An "entity transaction" is a transaction transferring control of an
-organization, or substantially all assets of one, or subdividing an
-organization, or merging organizations.  If propagation of a covered
-work results from an entity transaction, each party to that
-transaction who receives a copy of the work also receives whatever
-licenses to the work the party's predecessor in interest had or could
-give under the previous paragraph, plus a right to possession of the
-Corresponding Source of the work from the predecessor in interest, if
-the predecessor has it or can get it with reasonable efforts.
-
-  You may not impose any further restrictions on the exercise of the
-rights granted or affirmed under this License.  For example, you may
-not impose a license fee, royalty, or other charge for exercise of
-rights granted under this License, and you may not initiate litigation
-(including a cross-claim or counterclaim in a lawsuit) alleging that
-any patent claim is infringed by making, using, selling, offering for
-sale, or importing the Program or any portion of it.
-
-  11. Patents.
-
-  A "contributor" is a copyright holder who authorizes use under this
-License of the Program or a work on which the Program is based.  The
-work thus licensed is called the contributor's "contributor version".
-
-  A contributor's "essential patent claims" are all patent claims
-owned or controlled by the contributor, whether already acquired or
-hereafter acquired, that would be infringed by some manner, permitted
-by this License, of making, using, or selling its contributor version,
-but do not include claims that would be infringed only as a
-consequence of further modification of the contributor version.  For
-purposes of this definition, "control" includes the right to grant
-patent sublicenses in a manner consistent with the requirements of
-this License.
-
-  Each contributor grants you a non-exclusive, worldwide, royalty-free
-patent license under the contributor's essential patent claims, to
-make, use, sell, offer for sale, import and otherwise run, modify and
-propagate the contents of its contributor version.
-
-  In the following three paragraphs, a "patent license" is any express
-agreement or commitment, however denominated, not to enforce a patent
-(such as an express permission to practice a patent or covenant not to
-sue for patent infringement).  To "grant" such a patent license to a
-party means to make such an agreement or commitment not to enforce a
-patent against the party.
-
-  If you convey a covered work, knowingly relying on a patent license,
-and the Corresponding Source of the work is not available for anyone
-to copy, free of charge and under the terms of this License, through a
-publicly available network server or other readily accessible means,
-then you must either (1) cause the Corresponding Source to be so
-available, or (2) arrange to deprive yourself of the benefit of the
-patent license for this particular work, or (3) arrange, in a manner
-consistent with the requirements of this License, to extend the patent
-license to downstream recipients.  "Knowingly relying" means you have
-actual knowledge that, but for the patent license, your conveying the
-covered work in a country, or your recipient's use of the covered work
-in a country, would infringe one or more identifiable patents in that
-country that you have reason to believe are valid.
-
-  If, pursuant to or in connection with a single transaction or
-arrangement, you convey, or propagate by procuring conveyance of, a
-covered work, and grant a patent license to some of the parties
-receiving the covered work authorizing them to use, propagate, modify
-or convey a specific copy of the covered work, then the patent license
-you grant is automatically extended to all recipients of the covered
-work and works based on it.
-
-  A patent license is "discriminatory" if it does not include within
-the scope of its coverage, prohibits the exercise of, or is
-conditioned on the non-exercise of one or more of the rights that are
-specifically granted under this License.  You may not convey a covered
-work if you are a party to an arrangement with a third party that is
-in the business of distributing software, under which you make payment
-to the third party based on the extent of your activity of conveying
-the work, and under which the third party grants, to any of the
-parties who would receive the covered work from you, a discriminatory
-patent license (a) in connection with copies of the covered work
-conveyed by you (or copies made from those copies), or (b) primarily
-for and in connection with specific products or compilations that
-contain the covered work, unless you entered into that arrangement,
-or that patent license was granted, prior to 28 March 2007.
-
-  Nothing in this License shall be construed as excluding or limiting
-any implied license or other defenses to infringement that may
-otherwise be available to you under applicable patent law.
-
-  12. No Surrender of Others' Freedom.
-
-  If conditions are imposed on you (whether by court order, agreement or
-otherwise) that contradict the conditions of this License, they do not
-excuse you from the conditions of this License.  If you cannot convey a
-covered work so as to satisfy simultaneously your obligations under this
-License and any other pertinent obligations, then as a consequence you may
-not convey it at all.  For example, if you agree to terms that obligate you
-to collect a royalty for further conveying from those to whom you convey
-the Program, the only way you could satisfy both those terms and this
-License would be to refrain entirely from conveying the Program.
-
-  13. Use with the GNU Affero General Public License.
-
-  Notwithstanding any other provision of this License, you have
-permission to link or combine any covered work with a work licensed
-under version 3 of the GNU Affero General Public License into a single
-combined work, and to convey the resulting work.  The terms of this
-License will continue to apply to the part which is the covered work,
-but the special requirements of the GNU Affero General Public License,
-section 13, concerning interaction through a network will apply to the
-combination as such.
-
-  14. Revised Versions of this License.
-
-  The Free Software Foundation may publish revised and/or new versions of
-the GNU General Public License from time to time.  Such new versions will
-be similar in spirit to the present version, but may differ in detail to
-address new problems or concerns.
-
-  Each version is given a distinguishing version number.  If the
-Program specifies that a certain numbered version of the GNU General
-Public License "or any later version" applies to it, you have the
-option of following the terms and conditions either of that numbered
-version or of any later version published by the Free Software
-Foundation.  If the Program does not specify a version number of the
-GNU General Public License, you may choose any version ever published
-by the Free Software Foundation.
-
-  If the Program specifies that a proxy can decide which future
-versions of the GNU General Public License can be used, that proxy's
-public statement of acceptance of a version permanently authorizes you
-to choose that version for the Program.
-
-  Later license versions may give you additional or different
-permissions.  However, no additional obligations are imposed on any
-author or copyright holder as a result of your choosing to follow a
-later version.
-
-  15. Disclaimer of Warranty.
-
-  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
-APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
-HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
-OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
-THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
-IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
-ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
-
-  16. Limitation of Liability.
-
-  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
-WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
-THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
-GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
-USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
-DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
-PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
-EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
-SUCH DAMAGES.
-
-  17. Interpretation of Sections 15 and 16.
-
-  If the disclaimer of warranty and limitation of liability provided
-above cannot be given local legal effect according to their terms,
-reviewing courts shall apply local law that most closely approximates
-an absolute waiver of all civil liability in connection with the
-Program, unless a warranty or assumption of liability accompanies a
-copy of the Program in return for a fee.
-
-                     END OF TERMS AND CONDITIONS
-
-            How to Apply These Terms to Your New Programs
-
-  If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these terms.
-
-  To do so, attach the following notices to the program.  It is safest
-to attach them to the start of each source file to most effectively
-state the exclusion of warranty; and each file should have at least
-the "copyright" line and a pointer to where the full notice is found.
-
-    <one line to give the program's name and a brief idea of what it does.>
-    Copyright (C) <year>  <name of author>
-
-    This program is free software: you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-Also add information on how to contact you by electronic and paper mail.
-
-  If the program does terminal interaction, make it output a short
-notice like this when it starts in an interactive mode:
-
-    <program>  Copyright (C) <year>  <name of author>
-    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-    This is free software, and you are welcome to redistribute it
-    under certain conditions; type `show c' for details.
-
-The hypothetical commands `show w' and `show c' should show the appropriate
-parts of the General Public License.  Of course, your program's commands
-might be different; for a GUI interface, you would use an "about box".
-
-  You should also get your employer (if you work as a programmer) or school,
-if any, to sign a "copyright disclaimer" for the program, if necessary.
-For more information on this, and how to apply and follow the GNU GPL, see
-<https://www.gnu.org/licenses/>.
-
-  The GNU General Public License does not permit incorporating your program
-into proprietary programs.  If your program is a subroutine library, you
-may consider it more useful to permit linking proprietary applications with
-the library.  If this is what you want to do, use the GNU Lesser General
-Public License instead of this License.  But first, please read
-<https://www.gnu.org/licenses/why-not-lgpl.html>.
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

README.md

@@ -1,6 +1,6 @@
 <div align="center">
   
-  <img src="assets/images/logo.png" width="auto" alt="Logo">
+  <img src="docs/images/logo.png" width="auto" alt="Logo">
   <p>
     <strong>A lightweight Transformer training & inference framework</strong>
   </p>
@@ -8,7 +8,7 @@
 
 <div align="center">
   <img src="https://img.shields.io/badge/python-3.12+-blue.svg" alt="python">
-  <img src="https://img.shields.io/badge/license-GPL--3.0-blue.svg" alt="license">
+  <img src="https://img.shields.io/badge/license-Apache--2.0-blue.svg" alt="license">
   <img src="https://img.shields.io/github/v/tag/ViperEkura/AstrAI?label=Release&color=76bad9" alt="release">
   <img src="https://img.shields.io/github/stars/ViperEkura/AstrAI?style=flat&label=Stars&color=76bad9" alt="stars">
   <img src="https://img.shields.io/github/forks/ViperEkura/AstrAI?style=flat&label=Forks&color=76bad9" alt="forks">
@@ -17,17 +17,17 @@
 
 <div align="center">
   <a href="#english">English</a> •
-  <a href="assets/docs/README-zh-CN.md">中文</a> •
+  <a href="docs/README-zh-CN.md">中文</a> •
   <a href="https://github.com/ViperEkura/AstrAI/issues">Issue Tracker</a> •
   <a href="https://github.com/ViperEkura/AstrAI/discussions">Discussions</a> •
-  <a href="https://huggingface.co/ViperEk/">HuggingFace</a>
+  <a href="https://huggingface.co/ViperEkura">HuggingFace</a>
 </div>
 
 <br>
 
 ## 📖 Table of Contents
 
-- [Features](#features)
+- [Overview](#overview)
 - [Getting Started](#getting-started)
 - [Demo](#demo)
 - [Documentation](#documentation)
@@ -40,15 +40,19 @@
 <a id="english"></a>
 ## English
 
-### Features
+### Overview
 
-- 🚀 **High Performance**: Optimized for both training and inference with efficient parallelization.
-- 🔧 **Flexible**: Support for seq/sft/dpo/grpo training, customizable model architectures.
-- 💡 **Easy to Use**: Simple API with comprehensive examples and demos.
-- 📦 **Lightweight**: Minimal dependencies, easy to deploy.
-- 🔬 **Research‑Friendly**: Modular design, easy to experiment with new ideas.
-- 🤗 **HuggingFace-Style API**: AutoModel/AutoTokenizer APIs inspired by HuggingFace for easy model and tokenizer loading.
-- 🔌 **Dual API Compatibility**: Supports both OpenAI and Anthropic chat completion APIs out of the box.
+AstrAI is an end-to-end Transformer framework for building, training, evaluating, and serving models. It provides a compact PyTorch codebase for the complete model lifecycle, from declarative data preprocessing and distributed training to continuous-batching inference and OpenAI/Anthropic-compatible APIs.
+
+| Area | Capabilities |
+|---|---|
+| **Models** | Autoregressive language models and embedding models with GQA, MLA, MoE, RoPE, and extensible attention/FFN components |
+| **Training** | Pre-training (`seq`), supervised fine-tuning (`sft`), DPO, and GRPO with gradient accumulation, checkpointing, DDP, and FSDP |
+| **Data** | Declarative JSON preprocessing, configurable masking and packing, binary/JSONL storage, and streaming datasets |
+| **Inference** | Continuous batching, paged KV cache, radix prefix caching, streaming generation, and Torch/CUDA/FlashAttention backends |
+| **Serving** | FastAPI server with OpenAI and Anthropic chat completion protocols, including SSE streaming and tool calls |
+| **Evaluation** | Perplexity, MMLU, HumanEval, IFEval, IFD, ROUGE, and weight-analysis evaluation tools |
+| **Extensibility** | Factory and registry architecture for models, datasets, training strategies, callbacks, kernels, and protocol components |
 
 ### Getting Started
 
@@ -56,11 +60,14 @@ End-to-end walkthrough in 5 steps:
 
 **1. Install**
 
+AstrAI requires Python 3.12+ and pins PyTorch exactly to `2.11.0`. Training, `scripts/tools/generate.py`, generation evaluations, and the generation demos require CUDA; CPU support is limited to components with an explicit CPU device path, such as the HTTP server and direct-scoring evaluations.
+
 ```bash
 git clone https://github.com/ViperEkura/AstrAI.git
 cd AstrAI
-pip install -e .                                          # pure PyTorch (no CUDA kernels)
-# CSRC_KERNELS=true pip install -e . --no-build-isolation  # optional: fused CUDA kernels
+pip install -e .                                          # kernels auto-build when nvcc + CUDA are detected
+# CSRC_KERNELS=false pip install -e .                     # skip kernels (pure PyTorch)
+# CSRC_KERNELS=true pip install -e . --no-build-isolation  # force the fused CUDA kernel build
 # pip install -e ".[dev]"                                  # dev dependencies (pytest, ruff)
 ```
 
@@ -132,7 +139,7 @@ Check out the demos in the `scripts/demo/` folder:
 # Download model weights (required before running demos)
 python scripts/demo/download.py                      # model → params/
 
-# Interactive streaming chat (multi-turn, maintains history)
+# Single-turn interactive streaming prompt loop (no conversation history)
 python scripts/demo/stream_chat.py
 # Type your message after >>, type !exit to quit
 
@@ -183,8 +190,11 @@ docker run --gpus all -v /path/to/data:/data -it astrai:latest
 # Docker Compose (GPU, default)
 docker compose up -d
 
-# Docker Compose (CPU only)
+# Docker Compose CPU server profile (CUDA-only generation scripts/demos are unavailable)
 docker compose --profile cpu up -d
+
+# YAML-driven serving (see serve.yaml; up/run/down/logs/status...)
+bash scripts/serve.sh up
 ```
 
 > **Note**: `--gpus all` is required for CUDA support. Without it, `torch.cuda.is_available()` will return `False`.
@@ -213,18 +223,25 @@ curl -X POST http://localhost:8000/v1/messages \
 curl http://localhost:8000/health
 ```
 
-See [Inference Guide](assets/docs/inference.md) for SSE streaming format, error codes, and stats endpoint.
+See [Inference Guide](docs/guides/inference.md) for SSE streaming format, error codes, and stats endpoint.
 
 ### Documentation
 
 | Document | Description |
 |----------|-------------|
-| [CLI Reference](./assets/docs/params.md) | Parameters for all CLI tools (train, server, generate, preprocess) |
-| [Architecture](./assets/docs/architecture.md) | System architecture, class diagram & design patterns |
-| [Training](./assets/docs/training.md) | Training loop, strategies & formulas |
-| [Inference](./assets/docs/inference.md) | KVCache, continuous batching, sampling & HTTP API |
-| [Data Flow](./assets/docs/dataflow.md) | Data pipeline, storage backends & dataset architecture |
-| [Preprocessing](./assets/docs/preprocessing.md) | Declarative JSON-driven data preprocessing |
+| [Get Started](./docs/get-started.md) | Installation and quickstart |
+| [CLI Reference](./docs/guides/params.md) | Parameters for all CLI tools (train, server, generate, preprocess) |
+| [Preprocessing](./docs/guides/preprocessing.md) | Declarative JSON-driven data preprocessing |
+| [Training](./docs/guides/training.md) | Training loop, strategies & formulas |
+| [Inference](./docs/guides/inference.md) | KVCache, continuous batching, sampling & HTTP API |
+| [Evaluation](./docs/guides/evaluation.md) | HumanEval, MMLU, PPL, ROUGE, IFD, IFEval |
+| [Distributed](./docs/guides/distributed.md) | Multi-GPU DDP / FSDP training |
+| [Architecture](./docs/developer/architecture.md) | System architecture, class diagram & design patterns |
+| [Data Flow](./docs/developer/dataflow.md) | Data pipeline, storage backends & dataset architecture |
+| [Internals](./docs/developer/internals.md) | Training internals: loss formulas, callback lifecycle, KV cache |
+| [CUDA Kernels](./docs/developer/cuda_kernels.md) | Custom CUDA attention kernels & benchmarks |
+| [Docker Serving](./docs/developer/docker-serving.md) | YAML-driven containerized serving (`serve.yaml`, `serve.sh`) |
+| [Docker Training](./docs/developer/docker-training.md) | YAML-driven containerized training (`train.yaml`, `train.sh`) |
 
 ### Contributing
 
@@ -241,14 +258,14 @@ For major changes, please open an issue first to discuss what you would like to
 
 - **GitHub Issues**: [Issue Tracker](https://github.com/ViperEkura/AstrAI/issues)
 - **Discussions**: [GitHub Discussions](https://github.com/ViperEkura/AstrAI/discussions)
-- **HuggingFace**: [Model Hub](https://huggingface.co/ViperEk)
+- **HuggingFace**: [Model Hub](https://huggingface.co/ViperEkura)
 
 ### License
 
-This project is licensed under the [GPL-3.0 License](LICENSE).
+This project is licensed under the [Apache-2.0 License](LICENSE).
 
 ---
 
 <div align="center">
   <em>A lightweight Transformer framework designed for both high performance and ease of use.</em>
-</div>
+</div>

assets/docs/dataflow.md

@@ -1,112 +0,0 @@
-# Data Flow
-
-This document describes the data pipeline: from raw text to model input tensors. For creating preprocessing configs, see [Preprocessing Guide](preprocessing.md).
-
-## Contents
-
-- [Overview](#overview)
-- [Data Preparation](#data-preparation) — tokenization, format detection, backends
-- [Data Keys by Training Type](#data-keys-by-training-type)
-- [Dataset Architecture](#dataset-architecture)
-- [Sampler](#sampler)
-- [DataLoader](#dataloader)
-
-## Overview
-
-```
-JSONL Lines → Pipeline (mask builder) → Tokenized Tensors
-                                              ↓
-                                      .h5 or .bin storage
-                                              ↓
-                                      Store.load()
-                                              ↓
-                                      Store.fetch(begin, end, keys)
-                                              ↓
-                                      BaseDataset.__getitem__(idx)
-                                              ↓
-                                      Sampler → DataLoader → Training / Inference
-```
-
-## Data Preparation
-
-Raw text is tokenized via `AutoTokenizer.encode()` and saved as HDF5 (`.h5`) or binary (`.bin` + `meta.json`) files with keyed tensor groups.
-
-### Tokenization
-
-The `Pipeline` reads JSONL lines, applies the mask builder (see [Preprocessing](preprocessing.md)), and produces flat token sequences:
-
-```python
-# Per JSONL line: messages → chat template → token IDs + loss mask
-tokens = tokenizer.encode(rendered_text)        # List[int]
-loss_mask = [0, 0, 0, 1, 1, 1, 1, 1, 1]        # 0=masked, 1=train
-# Stored as flat tensors, packed with other lines by packing strategy
-```
-
-The output `meta.json` records the storage format, key names, dtype, total token count, and tensor shapes for each shard.
-
-### Format Detection
-
-`detect_format(load_path)` inspects the path:
-
-- If `load_path` is a file: checks suffix — `.h5`/`.hdf5` → `"h5"`, `.jsonl` → `"jsonl"`, unknown suffix raises `ValueError`
-- If `load_path` is a directory: recursively globs for `*.h5`/`*.hdf5` files → `"h5"`, `*.bin` + `**/meta.json` → `"bin"`, or `*.jsonl` + `dataset_config.json` → `"jsonl"`
-
-### Store Backends
-
-Storage format is auto-detected by `detect_format()`; backends are dispatched via registry:
-
-```
-StoreFactory.create("h5")    → H5Store
-StoreFactory.create("bin")   → MmapStore
-StoreFactory.create("jsonl") → JsonlStore
-```
-
-**H5Store**: Reads HDF5 files. Tensors are loaded into host memory and normalized into segmented storage.
-
-**MmapStore**: Memory-maps `.bin` files. OS page cache sharing is native — no explicit `share_memory_()` needed. Uses `torch.from_numpy(np.memmap(...))`.
-
-**JsonlStore**: On-the-fly tokenization of raw JSONL files at load time. Requires a `dataset_config.json` alongside the `.jsonl` files following the same `PipelineConfig` schema with an additional `tokenizer_path` field.
-
-All backends normalise tensors into `Store._data[Dict[str, List[Tensor]]]` + `Store._cum[Dict[str, List[int]]]` (cumulative lengths for bisect-based indexing).
-
-## Data Keys by Training Type
-
-| Type | Storage Keys |
-|------|-------------|
-| `seq` | `sequence` (→ input_ids, target_ids via offset-by-1) |
-| `sft` | `sequence`, `loss_mask`, `position_ids` |
-| `dpo` | `chosen`, `rejected`, `chosen_mask`, `rejected_mask` |
-| `grpo` | `prompts`, `responses`, `masks`, `rewards` |
-
-## Dataset Architecture
-
-```
-DatasetFactory.load(train_type, load_path, window_size, stride=None, storage_type=None)
-  → BaseDataset.load(load_path, storage_type=None)
-    → detect_format(load_path)
-    → StoreFactory.create(storage_type)
-    → Store.load(load_path)
-      → _normalize(raw)  # base Store, shared by both backends
-        → Store._data[Dict[str, List[Tensor]]] + _cum[Dict[str, List[int]]]
-          → BaseDataset.__getitem__(idx)
-            → get_index(idx) → [begin, end)
-            → Store.fetch(begin, end, keys) → Tensor / Dict[str, Tensor]
-```
-
-`window_size` = max input length, `stride` = step between consecutive samples (defaults to `window_size`, optional). `storage_type` defaults to `None` (auto-detect via `detect_format`).
-
-`Store.fetch(begin, end, keys)` accepts a single key (`str`) returning a `Tensor`, or a list of keys returning `Dict[str, Tensor]`. Internally uses `bisect` across multi-segment tensors. Raises `RuntimeError("Store not loaded")` if called before `load()`.
-
-## Sampler
-
-`ResumableDistributedSampler` supports checkpoint-aware distributed sampling:
-
-- Tracks `start_epoch` / `start_iter` for resume
-- Shuffle via `torch.Generator(seed + epoch)`
-- Per-replica index slicing for DDP
-
-## DataLoader
-
-Standard PyTorch `DataLoader` with configurable `batch_size`, `num_workers`, `pin_memory`, `prefetch_factor`. Sampler produces indices; dataloader fetches tensor batches via `__getitem__`.
-
-> Document Update Time: 2026-07-09

assets/docs/inference.md

@@ -1,252 +0,0 @@
-# Inference
-
-## Contents
-
-- [KV Cache](#kv-cache)
-- [KVCache System](#kvcache-system)
-- [Continuous Batching](#continuous-batching)
-- [Sampling](#sampling-strategy-pattern)
-- [Protocol Handlers](#protocol-handlers-strategy-pattern)
-- [Engine & GenerateResult](#engine--generateresult)
-- [HTTP API](#http-api) — endpoints, SSE, errors, stats
-- [Engine API](#engine-api)
-
-## KV Cache
-
-At decode time, only the last query token matters. All previous K/V are cached to avoid recomputation:
-
-$$
-o_n = \sum_j \text{softmax}\left(\frac{q_n k_j}{\sqrt{d_k}}\right) v_j
-$$
-
-RoPE is applied **before** KV cache write, not after — otherwise position encoding drift occurs.
-
-## KVCache System
-
-Seven classes working together, with two concrete cache implementations:
-
-### ContiguousCache (default)
-
-```
-ContiguousCache (simple contiguous per-slot cache)
-  ├── ContiguousCacheView  bundles k/v tensors + slot indices for attention layers
-```
-
-Created by default when no cache is passed to `InferenceScheduler`. Each task occupies a fixed slot of `[max_seq_len, n_kv_heads, head_dim]`. Simple and efficient for small-to-medium batch sizes.
-
-### PageCache (paged with prefix sharing)
-
-```
-PageCache (paged KV cache with prefix sharing, alternative)
-  ├── PagePool               orchestrates page allocation + prefix matching
-  │     ├── Allocator         bitmask-based page allocator + ref-count + LRU
-  │     └── PrefixCache       hash-based prefix matching (page_hash via polynomial hash)
-  ├── TaskTable              maps task_id → page_table + cached token count
-  ├── Storage                k_cache / v_cache tensors (n_layers × n_pages × page_size × n_kv_heads × head_dim)
-  └── PageCacheView          bundles Storage + page_table + total_len for attention layers
-```
-
-`isinstance(cache, KVCache)` checks dispatch to the correct view. Both implement the abstract `KVCache` interface used by `Executor` and `InferenceScheduler`.
-
-## Continuous Batching
-
-`InferenceScheduler` runs a daemon thread with a 4-phase loop:
-
-```
-1. Cleanup → Remove finished tasks, free KV cache slots/pages
-2. Refill  → Pop from waiting_queue, task_alloc resources, activate
-3. Prefill → Group by (prompt_len, start_pos), run full forward
-4. Decode  → Run single-token forward for each same-position group
-```
-
-## Sampling (Strategy Pattern)
-
-```
-BaseSamplingStrategy (ABC)
-  ├── TemperatureStrategy
-  ├── TopKStrategy
-  ├── TopPStrategy
-  └── SamplingPipeline
-```
-
-`SamplingPipeline` composes them: Temperature → Top-K → Top-P → softmax → multinomial.  
-`sample()` is a convenience shortcut for one-shot usage.
-
-## Protocol Handlers (Strategy Pattern)
-
-```python
-class ProtocolHandler:  # concrete orchestrator
-    def __init__(self, request, engine, builder): ...
-    async def handle(self):
-        prompt, ctx, stops = builder.prepare(request, engine)
-        agen = engine.generate_async(prompt, ...)
-        if stream: self._handle_stream(agen, ctx, stops)
-        else:      return await self._handle_non_stream(agen, ctx, stops)
-```
-
-`ResponseBuilder` (ABC): `prepare()`, `format_stream_start()`, `format_chunk()`, `format_stream_end()`, `format_response()`.
-
-`OpenAIResponseBuilder` → `/v1/chat/completions`, `AnthropicResponseBuilder` → `/v1/messages`.
-
-Adding a protocol = one builder file, no handler subclassing needed.
-
-## Engine & GenerateResult
-
-```
-InferenceEngine
-  ├── generate(prompt, stream, ...) → str | List[str] | Generator
-  ├── generate_with_request(req)    → same
-  ├── generate_async(prompt, ...)   → AsyncGenerator
-  ├── get_stats()                   → Dict
-  └── shutdown()
-```
-
-`GenerateResult` uses `Condition` for non-streaming (`wait_completion()`) and `Event` for streaming (`wait()`). Stream callback is `cb(token)`.
-
-## HTTP API
-
-```
-POST /v1/chat/completions   OpenAI
-POST /v1/messages            Anthropic
-GET  /health                 {"status":"ok","model_loaded":true}
-GET  /stats                  scheduler statistics
-```
-
-### OpenAI
-
-```bash
-curl -X POST http://localhost:8000/v1/chat/completions \
-  -H "Content-Type: application/json" \
-  -d '{"messages":[{"role":"user","content":"Hello"}],"max_tokens":512}'
-```
-
-Response:
-```json
-{
-  "id": "chatcmpl-abc123",
-  "object": "chat.completion",
-  "created": 1717000000,
-  "model": "astrai",
-  "choices": [{"index": 0, "message": {"role": "assistant", "content": "Hello!"}, "finish_reason": "stop"}],
-  "usage": {"prompt_tokens": 5, "completion_tokens": 10, "total_tokens": 15}
-}
-```
-
-Streaming SSE: `object: "chat.completion.chunk"` — starts with role delta, then token chunks, ends with finish chunk + usage stats, then `data: [DONE]`.
-
-### Anthropic
-
-```bash
-curl -X POST http://localhost:8000/v1/messages \
-  -H "Content-Type: application/json" \
-  -d '{"model":"astrai","system":"You are helpful.","messages":[{"role":"user","content":"Hello"}],"max_tokens":512}'
-```
-
-Supports `stop_sequences` and streaming via `event: content_block_delta`.
-
-### GenerationRequest Parameters
-
-| Param | Type | Default | Description |
-|-------|------|---------|-------------|
-| `messages` | List[dict] | required | Chat messages (role, content) |
-| `top_k` | int | 50 | Top-k count |
-| `top_p` | float | 1.0 | Nucleus threshold |
-| `temperature` | float | 1.0 | Sampling temperature (> 0.0) |
-| `max_tokens` | Optional[int] | None | Max generation length |
-| `stream` | bool | False | Stream output |
-
-### SSE Streaming Format
-
-**OpenAI** (`/v1/chat/completions`, `stream=true`):
-
-```
-data: {"id":"chatcmpl-...","object":"chat.completion.chunk","created":...,"model":"astrai",
-       "choices":[{"index":0,"delta":{"role":"assistant"},"finish_reason":null}]}
-
-data: {"id":"chatcmpl-...","object":"chat.completion.chunk","created":0,"model":"astrai",
-       "choices":[{"index":0,"delta":{"content":"Hello"},"finish_reason":null}]}
-
-data: {"id":"chatcmpl-...","object":"chat.completion.chunk","created":...,"model":"astrai",
-       "choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}
-
-data: {"prompt_tokens":5,"completion_tokens":1,"total_tokens":6}
-
-data: [DONE]
-```
-
-**Anthropic** (`/v1/messages`, `stream=true`):
-
-```
-event: message_start
-data: {"type":"message_start","message":{"id":"msg_...","model":"astrai","role":"assistant",
-       "content":[],"usage":{"input_tokens":0}}}
-
-event: content_block_start
-data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}
-
-event: content_block_delta
-data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Hello"}}
-
-event: content_block_stop
-data: {"type":"content_block_stop","index":0}
-
-event: message_delta
-data: {"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},"usage":{...}}
-
-event: message_stop
-data: {"type":"message_stop"}
-```
-
-### Error Responses
-
-The server returns standard HTTP status codes. Pydantic validation errors (e.g. missing required fields)
-are handled automatically by FastAPI with 422 status. The only application-level error is engine initialization:
-
-| Status | Meaning |
-|--------|---------|
-| 200 | Success |
-| 422 | Unprocessable entity (Pydantic validation) |
-| 503 | Service unavailable (model not loaded, engine not ready) |
-
-Error response body (503):
-
-```json
-{
-    "detail": "Engine not initialized"
-}
-```
-
-### Stats Endpoint
-
-```
-GET /stats
-```
-
-Response:
-
-```json
-{
-    "total_tasks": 128,
-    "total_tokens": 10240,
-    "active_tasks": 3,
-    "waiting_queue": 2
-}
-```
-
-## Engine API
-
-```python
-# Non-streaming
-engine.generate("Hello", stream=False)          # -> str
-engine.generate(["A", "B"], stream=False)       # -> List[str]
-
-# Streaming
-engine.generate("Hello", stream=True)           # -> Generator[str]
-engine.generate(["A", "B"], stream=True)        # -> Generator[Tuple[int, str]]
-
-# Async
-async for token in engine.generate_async("Hello", ...):    # -> AsyncGenerator[str]
-    print(token)
-```
-
-> Document Update Time: 2026-07-09

astrai/__init__.py

@@ -1,4 +1,4 @@
-__version__ = "1.3.9"
+__version__ = "1.3.13"
 __author__ = "ViperEkura"
 
 from astrai.config import (
@@ -12,20 +12,15 @@ from astrai.config import (
 from astrai.dataset import (
     BaseDataset,
     DatasetFactory,
-    ResumableDistributedSampler,
+    RDSampler,
     Store,
     StoreFactory,
 )
 from astrai.factory import BaseFactory
-from astrai.inference import (
-    GenerationRequest,
-    InferenceEngine,
-    ProtocolHandler,
-    SamplingPipeline,
-    get_app,
-    run_server,
-    sample,
-)
+from astrai.inference import InferenceEngine, get_app, run_server, sample
+from astrai.inference.network import ProtocolHandler
+from astrai.inference.runtime.sample import SamplingPipeline
+from astrai.logging import setup_logging
 from astrai.model import (
     AutoModel,
     AutoRegressiveLM,
@@ -71,13 +66,12 @@ __all__ = [
     "EmbeddingEncoder",
     "EncoderConfig",
     "ExecutorFactory",
-    "GenerationRequest",
     "InferenceEngine",
     "LoRAConfig",
     "Pipeline",
     "PipelineConfig",
     "ProtocolHandler",
-    "ResumableDistributedSampler",
+    "RDSampler",
     "SamplingPipeline",
     "SchedulerFactory",
     "Store",
@@ -94,5 +88,8 @@ __all__ = [
     "only_on_rank",
     "run_server",
     "sample",
+    "setup_logging",
     "spawn_parallel_fn",
 ]
+
+setup_logging()

astrai/config/base.py

@@ -1,92 +1,32 @@
 import json
-from dataclasses import MISSING, dataclass, fields
+from dataclasses import asdict
 from pathlib import Path
-from typing import Any, Dict, Optional, Self, Union, get_type_hints
+from typing import Any, Dict, Self, Union
+
+from pydantic import ConfigDict
+from pydantic.dataclasses import dataclass
 
 
-@dataclass
+@dataclass(config=ConfigDict(use_attribute_docstrings=True))
 class BaseConfig:
     def to_dict(self) -> Dict[str, Any]:
-        d = {}
-        for fld in fields(self):
-            v = getattr(self, fld.name)
-            if isinstance(v, (str, int, float, bool)):
-                d[fld.name] = v
-            elif v is None:
-                d[fld.name] = None
-            elif isinstance(v, (dict, list, tuple)):
-                try:
-                    val = list(v) if isinstance(v, tuple) else v
-                    json.dumps(val)
-                    d[fld.name] = val
-                except (TypeError, ValueError):
-                    pass
-            elif isinstance(v, BaseConfig):
-                d[fld.name] = v.to_dict()
-            elif hasattr(v, "__dataclass_fields__"):
-                sub = {}
-                for f in fields(v):
-                    a = getattr(v, f.name)
-                    sub[f.name] = list(a) if isinstance(a, tuple) else a
-                d[fld.name] = sub
-        return d
+        result = {}
+        for k, v in asdict(self).items():
+            if isinstance(v, tuple):
+                v = list(v)
+            try:
+                json.dumps(v)
+                result[k] = v
+            except (TypeError, ValueError):
+                # Skip non-serializable runtime objects (e.g. model_fn, dataset).
+                # TrainConfig mixes hyperparams with callables/datasets; only the
+                # JSON-serializable subset is written to checkpoint meta.
+                pass
+        return result
 
     @classmethod
     def from_dict(cls, d: Dict[str, Any]) -> Self:
-        hints = get_type_hints(cls)
-        inst = cls.__new__(cls)
-        for fld in fields(cls):
-            if fld.name in d:
-                v = d[fld.name]
-                target = cls._unwrap_optional(hints.get(fld.name))
-                if target is not None:
-                    try:
-                        v = cls._coerce(v, target)
-                    except (TypeError, ValueError):
-                        pass
-                object.__setattr__(inst, fld.name, v)
-            elif fld.default is not MISSING:
-                object.__setattr__(inst, fld.name, fld.default)
-            elif fld.default_factory is not MISSING:
-                object.__setattr__(inst, fld.name, fld.default_factory())
-            else:
-                object.__setattr__(inst, fld.name, None)
-        return inst
-
-    @staticmethod
-    def _unwrap_optional(tp) -> Optional[type]:
-        if tp is None:
-            return None
-        origin = getattr(tp, "__origin__", None)
-        if origin is not None:
-            args = getattr(tp, "__args__", ())
-            non_none = [a for a in args if a is not type(None)]
-            return non_none[0] if non_none else None
-        return tp
-
-    @staticmethod
-    def _coerce(value: Any, target_type: type) -> Any:
-        if target_type is bool and isinstance(value, bool):
-            return value
-        if (
-            target_type is int
-            and isinstance(value, (int, float))
-            and not isinstance(value, bool)
-        ):
-            return int(value)
-        if (
-            target_type is float
-            and isinstance(value, (int, float))
-            and not isinstance(value, bool)
-        ):
-            return float(value)
-        if target_type is str and isinstance(value, str):
-            return value
-        if isinstance(value, target_type):
-            return value
-        if isinstance(value, dict) and issubclass(target_type, BaseConfig):
-            return target_type.from_dict(value)
-        raise TypeError
+        return cls(**d)
 
     @classmethod
     def from_file(cls, path: Union[str, Path]) -> Self:

astrai/config/model_config.py

@@ -1,9 +1,14 @@
-from dataclasses import dataclass
 from typing import Any, Dict, Optional
 
+from pydantic import field_validator
+from pydantic.dataclasses import dataclass
+
 from astrai.config.base import BaseConfig
 from astrai.factory import BaseFactory
 
+_ATTN_TYPES = frozenset({"gqa", "mla"})
+_FFN_TYPES = frozenset({"mlp", "moe"})
+
 
 class ConfigFactory(BaseFactory[BaseConfig]):
     """Factory that dispatches config classes by ``model_type``."""
@@ -17,7 +22,12 @@ class ConfigFactory(BaseFactory[BaseConfig]):
 
 @dataclass
 class BaseModelConfig(BaseConfig):
-    """Base config with ``model_type`` dispatch and file I/O."""
+    """Base config with ``model_type`` dispatch and file I/O.
+
+    Args:
+        model_type (Optional[str]): Model type identifier for AutoModel dispatch. Defaults to None.
+        neftune_alpha (float): NEFTune noise alpha, 0=disabled, typical: 5.0. Defaults to 0.0.
+    """
 
     model_type: Optional[str] = None
     neftune_alpha: float = 0.0
@@ -26,57 +36,143 @@ class BaseModelConfig(BaseConfig):
 @dataclass
 @ConfigFactory.register("autoregressive_lm")
 class AutoRegressiveLMConfig(BaseModelConfig):
-    """Configuration for autoregressive language model."""
+    """Configuration for autoregressive language model.
+
+    Args:
+        model_type (Optional[str]): Model type identifier for AutoModel dispatch. Defaults to None.
+        neftune_alpha (float): NEFTune noise alpha, 0=disabled, typical: 5.0. Defaults to 0.0.
+        vocab_size (Optional[int]): Vocabulary size. Defaults to None.
+        hidden_size (Optional[int]): Hidden dimension size. Defaults to None.
+        num_hidden_layers (Optional[int]): Number of transformer layers. Defaults to None.
+        rms_norm_eps (Optional[float]): Epsilon for RMSNorm. Defaults to None.
+        intermediate_size (Optional[int]): Intermediate size in FFN. Defaults to None.
+        tie_word_embeddings (Optional[bool]): Whether to tie embedding and lm_head weights. Defaults to None.
+        max_position_embeddings (Optional[int]): Maximum sequence length the model was trained with. Defaults to None.
+        rope_theta (Optional[float]): Base frequency for RoPE. Defaults to None.
+        rope_scaling (Optional[dict]): RoPE scaling config, e.g. {"type": "linear", "factor": 4.0}. Defaults to None.
+        attn_type (str): Attention type: 'gqa' or 'mla'. Defaults to "gqa".
+        num_attention_heads (Optional[int]): Number of query attention heads. Defaults to None.
+        num_key_value_heads (Optional[int]): Number of key/value heads for GQA. Defaults to None.
+        use_qk_norm (Optional[bool]): Whether to apply RMSNorm to Q/K. Defaults to None.
+        use_gated_attention (Optional[bool]): Whether to use gated attention. Defaults to None.
+        kv_lora_rank (Optional[int]): KV compression rank, MLA only. Defaults to None.
+        qk_nope_head_dim (Optional[int]): Non-RoPE head dimension, MLA only. Defaults to None.
+        qk_rope_head_dim (Optional[int]): RoPE head dimension, MLA only. Defaults to None.
+        ffn_type (str): FFN type: 'mlp' or 'moe'. Defaults to "mlp".
+        n_routed_experts (Optional[int]): Number of routed experts, MoE only. Defaults to None.
+        n_shared_experts (Optional[int]): Number of shared experts, MoE only. Defaults to None.
+        n_activated_experts (Optional[int]): Number of activated experts per token, MoE only. Defaults to None.
+        topk_method (Optional[str]): Top-k routing method, MoE only. Defaults to None.
+        moe_intermediate_size (Optional[int]): Expert hidden dim, defaults to intermediate_size if None. MoE only.
+        shared_expert_intermediate_size (Optional[int]): Shared expert hidden dim, defaults to intermediate_size if None. MoE only.
+        norm_topk_prob (bool): Normalize top-k routing probabilities. Defaults to True.
+        decoder_sparse_step (int): Frequency of MoE layers, 1=every layer. Defaults to 1.
+        mlp_only_layers (Optional[list[int]]): Layer indices using dense MLP instead of MoE. Defaults to None.
+    """
 
     vocab_size: Optional[int] = None
-    dim: Optional[int] = None
-    n_layers: Optional[int] = None
-    norm_eps: Optional[float] = None
-    dim_ffn: Optional[int] = None
-    tie_weight: Optional[bool] = None
-
-    max_len: Optional[int] = None
+    hidden_size: Optional[int] = None
+    num_hidden_layers: Optional[int] = None
+    rms_norm_eps: Optional[float] = None
+    intermediate_size: Optional[int] = None
+    tie_word_embeddings: Optional[bool] = None
+    max_position_embeddings: Optional[int] = None
     rope_theta: Optional[float] = None
     rope_scaling: Optional[dict] = None
-
     attn_type: str = "gqa"
-    n_heads: Optional[int] = None
-    n_kv_heads: Optional[int] = None
+    num_attention_heads: Optional[int] = None
+    num_key_value_heads: Optional[int] = None
     use_qk_norm: Optional[bool] = None
     use_gated_attention: Optional[bool] = None
-
     kv_lora_rank: Optional[int] = None
     qk_nope_head_dim: Optional[int] = None
     qk_rope_head_dim: Optional[int] = None
-
     ffn_type: str = "mlp"
     n_routed_experts: Optional[int] = None
     n_shared_experts: Optional[int] = None
     n_activated_experts: Optional[int] = None
     topk_method: Optional[str] = None
+    moe_intermediate_size: Optional[int] = None
+    shared_expert_intermediate_size: Optional[int] = None
+    norm_topk_prob: bool = True
+    decoder_sparse_step: int = 1
+    mlp_only_layers: Optional[list[int]] = None
+    moe_aux_loss_coef: float = 0.01
+
+    @field_validator("attn_type")
+    def _validate_attn_type(cls, v: str) -> str:
+        if v not in _ATTN_TYPES:
+            raise ValueError(
+                f"attn_type must be one of {sorted(_ATTN_TYPES)}, got {v!r}"
+            )
+        return v
+
+    @field_validator("ffn_type")
+    def _validate_ffn_type(cls, v: str) -> str:
+        if v not in _FFN_TYPES:
+            raise ValueError(f"ffn_type must be one of {sorted(_FFN_TYPES)}, got {v!r}")
+        return v
+
+    @field_validator("decoder_sparse_step")
+    def _validate_decoder_sparse_step(cls, v: int) -> int:
+        if v < 1:
+            raise ValueError(f"decoder_sparse_step must be at least 1, got {v}")
+        return v
 
 
 @dataclass
 @ConfigFactory.register("embedding")
 class EncoderConfig(BaseModelConfig):
-    """Configuration for embedding encoder model."""
+    """Configuration for embedding encoder model.
+
+    Args:
+        model_type (Optional[str]): Model type identifier for AutoModel dispatch. Defaults to None.
+        neftune_alpha (float): NEFTune noise alpha, 0=disabled, typical: 5.0. Defaults to 0.0.
+        vocab_size (Optional[int]): Vocabulary size. Defaults to None.
+        hidden_size (Optional[int]): Hidden dimension size. Defaults to None.
+        num_hidden_layers (Optional[int]): Number of transformer layers. Defaults to None.
+        rms_norm_eps (Optional[float]): Epsilon for RMSNorm. Defaults to None.
+        intermediate_size (Optional[int]): Intermediate size in FFN. Defaults to None.
+        max_position_embeddings (Optional[int]): Maximum sequence length the model was trained with. Defaults to None.
+        rope_theta (Optional[float]): Base frequency for RoPE. Defaults to None.
+        rope_scaling (Optional[dict]): RoPE scaling config, e.g. {"type": "linear", "factor": 4.0}. Defaults to None.
+        attn_type (str): Attention type: 'gqa' or 'mla'. Defaults to "gqa".
+        num_attention_heads (Optional[int]): Number of query attention heads. Defaults to None.
+        num_key_value_heads (Optional[int]): Number of key/value heads for GQA. Defaults to None.
+        use_qk_norm (Optional[bool]): Whether to apply RMSNorm to Q/K. Defaults to None.
+        use_gated_attention (Optional[bool]): Whether to use gated attention. Defaults to None.
+        ffn_type (str): FFN type: 'mlp' or 'moe'. Defaults to "mlp".
+        pooling_type (Optional[str]): Pooling strategy for embedding, e.g. 'mean', 'cls'. Defaults to None.
+        normalize_embeddings (Optional[bool]): Whether to L2-normalize output embeddings. Defaults to None.
+    """
 
     vocab_size: Optional[int] = None
-    dim: Optional[int] = None
-    n_layers: Optional[int] = None
-    norm_eps: Optional[float] = None
-    dim_ffn: Optional[int] = None
-
-    max_len: Optional[int] = None
+    hidden_size: Optional[int] = None
+    num_hidden_layers: Optional[int] = None
+    rms_norm_eps: Optional[float] = None
+    intermediate_size: Optional[int] = None
+    max_position_embeddings: Optional[int] = None
     rope_theta: Optional[float] = None
     rope_scaling: Optional[dict] = None
-
     attn_type: str = "gqa"
-    n_heads: Optional[int] = None
-    n_kv_heads: Optional[int] = None
+    num_attention_heads: Optional[int] = None
+    num_key_value_heads: Optional[int] = None
     use_qk_norm: Optional[bool] = None
     use_gated_attention: Optional[bool] = None
-
     ffn_type: str = "mlp"
     pooling_type: Optional[str] = None
     normalize_embeddings: Optional[bool] = None
+
+    @field_validator("attn_type")
+    def _validate_attn_type(cls, v: str) -> str:
+        if v not in _ATTN_TYPES:
+            raise ValueError(
+                f"attn_type must be one of {sorted(_ATTN_TYPES)}, got {v!r}"
+            )
+        return v
+
+    @field_validator("ffn_type")
+    def _validate_ffn_type(cls, v: str) -> str:
+        if v not in _FFN_TYPES:
+            raise ValueError(f"ffn_type must be one of {sorted(_FFN_TYPES)}, got {v!r}")
+        return v

astrai/config/preprocess_config.py

@@ -5,11 +5,19 @@ modes, both driven declaratively through ``input.sections`` or
 ``input.sources``.
 """
 
-from dataclasses import dataclass, field
+from dataclasses import field
 from typing import Dict, List, Optional
 
+from pydantic import field_validator
+from pydantic.dataclasses import dataclass
+
 from astrai.config.base import BaseConfig
 
+_PACKING_STRATEGIES = frozenset({"simple", "bfd", "bfd_split"})
+_TRUNCATION_MODES = frozenset({"keep_start", "keep_end"})
+_STORAGE_FORMATS = frozenset({"bin", "jsonl"})
+_POSITION_IDS_MODES = frozenset({"none", "doc_reset", "continuous"})
+
 
 @dataclass
 class InputConfig(BaseConfig):
@@ -25,6 +33,10 @@ class InputConfig(BaseConfig):
             "chosen": {"sections": [{"field": "chosen", ...}]},
             "rejected": {"sections": [{"field": "rejected", ...}]},
         }}}
+
+    Args:
+        sections (Optional[List[Dict]]): Section list for single-output mode. Defaults to None.
+        sources (Optional[Dict[str, Dict]]): Source map for multi-output mode, DPO/GRPO. Defaults to None.
     """
 
     sections: Optional[List[Dict]] = None
@@ -33,63 +45,67 @@ class InputConfig(BaseConfig):
 
 @dataclass
 class ProcessingConfig(BaseConfig):
-    """Processing configuration.
+    """Processing configuration for tokenization and packing.
 
-    Parameters
-    ----------
-    max_seq_len : int
-        Maximum sequence length (default: 2048).
-    min_chars : int
-        Minimum number of characters to keep (default: 50).
-    max_chars : int
-        Maximum number of characters to keep (default: 2_000_000).
-    max_items : Optional[int]
-        Maximum number of items to process (default: None, unlimited).
-    packing_strategy : str
-        How to pack sequences into a contiguous stream.
-
-        - ``"simple"``: sequential concatenation (default, backward compatible).
-        - ``"bfd"``: best-fit decreasing bin packing, minimises wasted tokens.
-        - ``"bfd_split"``: BFD with over-length sequences split into chunks.
-    max_packed_len : int
-        Maximum length of a packed bin. Sequences longer than this are
-        truncated or split depending on ``packing_strategy`` (default: 8192).
-    truncation_mode : str
-        How to truncate sequences longer than ``max_packed_len``.
-
-        - ``"keep_start"``: keep the first ``max_packed_len`` tokens (default).
-        - ``"keep_end"``: keep the last ``max_packed_len`` tokens.
+    Args:
+        max_seq_len (int): Maximum sequence length. Defaults to 2048.
+        min_chars (int): Minimum number of characters to keep. Defaults to 50.
+        max_chars (int): Maximum number of characters to keep. Defaults to 2_000_000.
+        max_items (Optional[int]): Maximum number of items to process, None=unlimited. Defaults to None.
+        batch_size (int): Number of records tokenized together. Defaults to 256.
+        packing_strategy (str): How to pack sequences: 'simple', 'bfd', or 'bfd_split'. Defaults to "simple".
+        max_packed_len (int): Maximum length of a packed bin. Defaults to 8192.
+        truncation_mode (str): How to truncate over-length sequences: 'keep_start' or 'keep_end'. Defaults to "keep_start".
     """
 
     max_seq_len: int = 2048
     min_chars: int = 50
     max_chars: int = 2_000_000
     max_items: Optional[int] = None
+    batch_size: int = 256
     packing_strategy: str = "simple"
     max_packed_len: int = 8192
     truncation_mode: str = "keep_start"
 
+    @field_validator("packing_strategy")
+    def _validate_packing_strategy(cls, v: str) -> str:
+        if v not in _PACKING_STRATEGIES:
+            raise ValueError(
+                f"packing_strategy must be one of {sorted(_PACKING_STRATEGIES)}, got {v!r}"
+            )
+        return v
+
+    @field_validator("truncation_mode")
+    def _validate_truncation_mode(cls, v: str) -> str:
+        if v not in _TRUNCATION_MODES:
+            raise ValueError(
+                f"truncation_mode must be one of {sorted(_TRUNCATION_MODES)}, got {v!r}"
+            )
+        return v
+
+    @field_validator("max_seq_len", "batch_size", "max_packed_len")
+    def _validate_positive_int(cls, v: int) -> int:
+        if v <= 0:
+            raise ValueError(f"must be positive, got {v}")
+        return v
+
+    @field_validator("min_chars")
+    def _validate_non_negative(cls, v: int) -> int:
+        if v < 0:
+            raise ValueError(f"min_chars must be non-negative, got {v}")
+        return v
+
 
 @dataclass
 class OutputConfig(BaseConfig):
-    """Output configuration.
+    """Output configuration for storage.
 
-    Parameters
-    ----------
-    domain_key : Optional[str]
-        Domain key for the output store (default: None).
-    storage_format : str
-        Storage format, one of ``"bin"``, ``"jsonl"`` (default: ``"bin"``).
-    max_tokens_per_shard : int
-        Maximum tokens per shard before splitting (default: 100_000_000).
-    dtype : Dict[str, str]
-        Per-key dtype overrides, e.g. ``{"input_ids": "int32"}`` (default: {}).
-    position_ids_mode : Optional[str]
-        How to compute position_ids in packed sequences.
-
-         - ``"none"``: do not generate (default).
-        - ``"doc_reset"``: reset to 0 at each document boundary.
-        - ``"continuous"``: sequential 0, 1, 2, ... (pretrain, single doc).
+    Args:
+        domain_key (Optional[str]): Domain key for the output store. Defaults to None.
+        storage_format (str): Storage format: 'bin' or 'jsonl'. Defaults to "bin".
+        max_tokens_per_shard (int): Maximum tokens per shard before splitting. Defaults to 100_000_000.
+        dtype (Dict[str, str]): Per-key dtype overrides, e.g. {"input_ids": "int32"}. Defaults to {}.
+        position_ids_mode (str): Position ids mode: 'none', 'doc_reset', or 'continuous'. Defaults to "doc_reset".
     """
 
     domain_key: Optional[str] = None
@@ -98,9 +114,36 @@ class OutputConfig(BaseConfig):
     dtype: Dict[str, str] = field(default_factory=dict)
     position_ids_mode: str = "doc_reset"
 
+    @field_validator("storage_format")
+    def _validate_storage_format(cls, v: str) -> str:
+        if v not in _STORAGE_FORMATS:
+            raise ValueError(
+                f"storage_format must be one of {sorted(_STORAGE_FORMATS)}, got {v!r}"
+            )
+        return v
+
+    @field_validator("position_ids_mode")
+    def _validate_position_ids_mode(cls, v: str) -> str:
+        if v not in _POSITION_IDS_MODES:
+            raise ValueError(
+                f"position_ids_mode must be one of {sorted(_POSITION_IDS_MODES)}, got {v!r}"
+            )
+        return v
+
 
 @dataclass
 class PipelineConfig(BaseConfig):
+    """Top-level preprocessing pipeline config.
+
+    Args:
+        version (int): Config schema version. Defaults to 1.
+        input (InputConfig): Input mapping config.
+        mask (Dict[str, str]): Per-field mask labels, e.g. {"system": "mask", "assistant": "train"}. Defaults to {}.
+        mask_default (str): Default mask label for unlisted fields. Defaults to "mask".
+        preprocessing (ProcessingConfig): Processing config.
+        output (OutputConfig): Output config.
+    """
+
     version: int = 1
     input: InputConfig = field(default_factory=InputConfig)
     mask: Dict[str, str] = field(default_factory=dict)

astrai/config/train_config.py

@@ -1,7 +1,9 @@
-from dataclasses import dataclass, field, fields
+from dataclasses import field
 from typing import Any, Callable, Dict, List, Optional
 
 import torch.nn as nn
+from pydantic import ConfigDict, field_validator, model_validator
+from pydantic.dataclasses import dataclass
 from torch.optim import Optimizer
 from torch.optim.lr_scheduler import LRScheduler
 from torch.utils.data import Dataset
@@ -9,142 +11,210 @@ from torch.utils.data import Dataset
 from astrai.config.base import BaseConfig
 from astrai.model.components.lora import LoRAConfig
 
-
-def required(**kw):
-    return {"required": True, **kw}
+TRAIN_TYPES = frozenset({"seq", "sft", "dpo", "grpo", "online_grpo", "online_dpo"})
+PARALLEL_MODES = frozenset({"none", "ddp", "fsdp"})
+BACKENDS = frozenset({"nccl", "gloo"})
+START_METHODS = frozenset({"spawn", "fork", "forkserver"})
+_COMPILE_MODES = frozenset({"default", "reduce-overhead", "max-autotune"})
 
 
-@dataclass
+@dataclass(config=ConfigDict(arbitrary_types_allowed=True))
 class TrainConfig(BaseConfig):
-    # basic setting
-    model_fn: Callable[[], nn.Module] = field(
-        default=None, metadata=required(help="Model factory for training.")
-    )
-    strategy: str = field(default=None, metadata=required(help="Training strategy."))
-    dataset: Dataset = field(
-        default=None, metadata=required(help="Dataset for training.")
-    )
-    optimizer_fn: Callable[[nn.Module], Optimizer] = field(
-        default=None, metadata=required(help="Optimizer factory for training.")
-    )
-    scheduler_fn: Callable[[Optimizer], LRScheduler] = field(
-        default=None, metadata=required(help="Scheduler factory for training.")
-    )
-    n_epoch: int = field(default=1, metadata={"help": "Number of epochs for training."})
-    batch_per_device: int = field(
-        default=4, metadata={"help": "Batch size per device."}
-    )
-    grad_accum_steps: int = field(
-        default=1, metadata={"help": "Number of iterations between steps."}
-    )
-    max_grad_norm: float = field(
-        default=1.0, metadata={"help": "Maximum gradient norm."}
-    )
-    gradient_checkpointing_modules: List[str] = field(
-        default_factory=list,
-        metadata={"help": "Module types to enable activation checkpointing for."},
-    )
+    """Training configuration.
 
-    # checkpoint setting
-    start_epoch: int = field(default=0, metadata={"help": "Start epoch for training."})
-    start_samples: int = field(
-        default=0,
-        metadata={
-            "help": "Start samples count (per rank). Superseded by checkpoint consumed_samples."
-        },
-    )
-    ckpt_dir: str = field(
-        default="./checkpoint", metadata={"help": "Checkpoint directory."}
-    )
-    ckpt_interval: int = field(
-        default=5000,
-        metadata={"help": "Number of optimizer steps between checkpoints."},
-    )
+    Combines hyperparameters with runtime objects (model_fn, dataset, etc.).
+    Only JSON-serializable fields are written to checkpoint meta via to_dict().
 
-    # lora setting
-    lora: Optional[LoRAConfig] = field(
-        default=None,
-        metadata={"help": "LoRA config. None means full fine-tuning."},
-    )
+    Args:
+        model_fn (Callable[[], nn.Module]): Model factory for training.
+        strategy (str): Training strategy (seq, sft, dpo, grpo, online_*).
+        dataset (Dataset): Dataset for training.
+        optimizer_fn (Callable[[nn.Module], Optimizer]): Optimizer factory for training.
+        optimizer_name (Optional[str]): Serializable built-in optimizer identifier. Defaults to None.
+        optimizer_hyperparameters (Dict[str, Any]): Serializable optimizer settings. Defaults to {}.
+        scheduler_fn (Callable[[Optimizer], LRScheduler]): Scheduler factory for training.
+        n_epoch (int): Number of epochs for training. Defaults to 1.
+        batch_per_device (int): Batch size per device. Defaults to 4.
+        grad_accum_steps (int): Number of iterations between optimizer steps. Defaults to 1.
+        max_grad_norm (Optional[float]): Maximum gradient norm. None disables clipping. Defaults to 1.0.
+        gradient_checkpointing_modules (List[type]): Module types to enable activation checkpointing for. Defaults to [].
+        compile_mode (Optional[str]): torch.compile mode: 'default', 'reduce-overhead', 'max-autotune', or None. Defaults to None.
+        start_epoch (int): Start epoch for training. Defaults to 0.
+        start_samples (int): Start samples count (per rank). Superseded by checkpoint consumed_samples. Defaults to 0.
+        ckpt_dir (str): Checkpoint directory. Defaults to "./checkpoint".
+        ckpt_interval (int): Number of optimizer steps between checkpoints. Defaults to 5000.
+        lora (Optional[LoRAConfig]): LoRA config. None means full fine-tuning. Defaults to None.
+        metrics (List[str]): Metrics to record during training. Defaults to ["loss", "lr", "grad_norm"].
+        random_seed (int): Random seed. Defaults to 3407.
+        num_workers (int): Number of workers for dataloader. Defaults to 0.
+        prefetch_factor (Optional[int]): Prefetch factor for dataloader. Defaults to None.
+        persistent_workers (bool): Keep DataLoader workers alive between epochs. Defaults to False.
+        pin_memory (bool): Pin memory for dataloader. Defaults to False.
+        collate_fn (Optional[Callable[[List[Any]], Any]]): Collate function for dataloader (e.g. dpo_collate_fn). Defaults to None.
+        nprocs (int): Number of processes for distributed training. Defaults to 1.
+        backend (str): Distributed training backend. Defaults to "nccl".
+        master_addr (str): Master address for distributed training. Defaults to "localhost".
+        master_port (str): Master port for distributed training. Defaults to "29500".
+        parallel_mode (str): Parallel strategy: none, ddp, fsdp. Defaults to "none".
+        start_method (str): Multiprocessing start method: spawn/fork/forkserver. Defaults to "spawn".
+        device_type (str): Device type for distributed training. Defaults to "cuda".
+        val_dataset (Optional[Dataset]): Dataset for validation. Defaults to None.
+        val_split (Optional[float]): Ratio to split from training dataset for validation, e.g. 0.05. Defaults to None.
+        val_step (int): Number of optimizer steps between validation runs. Defaults to 1000.
+        neftune_alpha (float): NEFTune noise alpha, 0=disabled, typical: 5.0. Defaults to 0.0.
+        moe_aux_loss_coef (float): Weight applied to the MoE load-balancing loss. Defaults to 0.01.
+        rollout_interval (int): Number of optimizer steps between online rollouts. Defaults to 512.
+        rollout_temperature (float): Sampling temperature for online rollout. Defaults to 0.7.
+        rollout_top_k (int): Top-k filtering for online rollout, 0=disable. Defaults to 0.
+        rollout_top_p (float): Top-p (nucleus) filtering for online rollout. Defaults to 0.9.
+        rollout_max_tokens (int): Maximum generated tokens per response in rollout. Defaults to 1024.
+        reward_model_fn (Optional[Callable]): Factory for reward model, required for online RL strategies. Defaults to None.
+        executor_kwargs (Dict[str, Any]): Extra kwargs passed to ExecutorFactory.create(). Defaults to {}.
+        strategy_kwargs (Dict[str, Any]): Extra strategy arguments. Defaults to {}.
+    """
 
-    # metric setting
-    log_dir: str = field(
-        default="./checkpoint/logs", metadata={"help": "Directory for metric logs."}
-    )
-    metrics: List[str] = field(
-        default_factory=lambda: ["loss", "lr", "grad_norm"],
-        metadata={"help": "Metrics to record during training."},
-    )
+    model_fn: Callable[[], nn.Module]
+    strategy: str
+    dataset: Dataset
+    optimizer_fn: Callable[[nn.Module], Optimizer]
+    scheduler_fn: Callable[[Optimizer], LRScheduler]
+    optimizer_name: Optional[str] = None
+    optimizer_hyperparameters: Dict[str, Any] = field(default_factory=dict)
+    n_epoch: int = 1
+    batch_per_device: int = 4
+    grad_accum_steps: int = 1
+    max_grad_norm: Optional[float] = 1.0
+    gradient_checkpointing_modules: List[type] = field(default_factory=list)
+    compile_mode: Optional[str] = None
 
-    # dataloader setting
-    random_seed: int = field(default=3407, metadata={"help": "Random seed."})
-    num_workers: int = field(
-        default=0, metadata={"help": "Number of workers for dataloader."}
-    )
-    prefetch_factor: Optional[int] = field(
-        default=None, metadata={"help": "Prefetch factor for dataloader."}
-    )
-    pin_memory: bool = field(
-        default=False, metadata={"help": "Pin memory for dataloader."}
-    )
+    start_epoch: int = 0
+    start_samples: int = 0
+    ckpt_dir: str = "./checkpoint"
+    ckpt_interval: int = 5000
 
-    # distributed training
-    nprocs: int = field(
-        default=1, metadata={"help": "Number of processes for distributed training."}
-    )
-    backend: str = field(
-        default="nccl", metadata={"help": "Distributed training backend."}
-    )
-    master_addr: str = field(
-        default="localhost",
-        metadata={"help": "Master address for distributed training."},
-    )
-    master_port: str = field(
-        default="29500", metadata={"help": "Master port for distributed training."}
-    )
-    parallel_mode: str = field(
-        default="none",
-        metadata={"help": "Parallel strategy: none, ddp, fsdp."},
-    )
-    start_method: str = field(
-        default="spawn",
-        metadata={"help": "Multiprocessing start method (spawn/fork/forkserver)."},
-    )
+    lora: Optional[LoRAConfig] = None
 
-    # others
-    device_type: str = field(
-        default="cuda", metadata={"help": "Device type for distributed training."}
-    )
-    val_dataset: Optional[Dataset] = field(
-        default=None, metadata={"help": "Dataset for validation."}
-    )
-    val_split: Optional[float] = field(
-        default=None,
-        metadata={
-            "help": "Ratio to split from training dataset for validation (e.g. 0.05). Ignored if val_dataset is set."
-        },
-    )
-    val_step: int = field(
-        default=1000,
-        metadata={"help": "Number of optimizer steps between validation runs."},
-    )
-    neftune_alpha: float = field(
-        default=0.0,
-        metadata={"help": "NEFTune noise alpha (0=disabled, typical: 5.0)."},
-    )
+    metrics: List[str] = field(default_factory=lambda: ["loss", "lr", "grad_norm"])
 
-    executor_kwargs: Dict[str, Any] = field(
-        default_factory=dict,
-        metadata={"help": "Extra kwargs passed to ExecutorFactory.create()."},
-    )
-    extra_kwargs: Dict[str, Any] = field(
-        default_factory=dict, metadata={"help": "Other arguments."}
-    )
+    random_seed: int = 3407
+    num_workers: int = 0
+    prefetch_factor: Optional[int] = None
+    persistent_workers: bool = False
+    pin_memory: bool = False
+    collate_fn: Optional[Callable[[List[Any]], Any]] = None
 
-    def __post_init__(self):
-        self.validate()
+    nprocs: int = 1
+    backend: str = "nccl"
+    master_addr: str = "localhost"
+    master_port: str = "29500"
+    parallel_mode: str = "none"
+    start_method: str = "spawn"
 
-    def validate(self):
-        for fld in fields(self):
-            if fld.metadata.get("required") and getattr(self, fld.name) is None:
-                raise ValueError(f"TrainConfig.{fld.name} is required but got None.")
+    device_type: str = "cuda"
+    val_dataset: Optional[Dataset] = None
+    val_split: Optional[float] = None
+    val_step: int = 1000
+    neftune_alpha: float = 0.0
+    moe_aux_loss_coef: float = 0.01
+
+    rollout_interval: int = 512
+    rollout_temperature: float = 0.7
+    rollout_top_k: int = 0
+    rollout_top_p: float = 0.9
+    rollout_max_tokens: int = 1024
+    reward_model_fn: Optional[Callable] = None
+
+    executor_kwargs: Dict[str, Any] = field(default_factory=dict)
+    strategy_kwargs: Dict[str, Any] = field(default_factory=dict)
+
+    @field_validator("strategy")
+    def _validate_strategy(cls, v: str) -> str:
+        if v not in TRAIN_TYPES:
+            raise ValueError(
+                f"strategy must be one of {sorted(TRAIN_TYPES)}, got {v!r}"
+            )
+        return v
+
+    @field_validator("parallel_mode")
+    def _validate_parallel_mode(cls, v: str) -> str:
+        if v not in PARALLEL_MODES:
+            raise ValueError(
+                f"parallel_mode must be one of {sorted(PARALLEL_MODES)}, got {v!r}"
+            )
+        return v
+
+    @field_validator("backend")
+    def _validate_backend(cls, v: str) -> str:
+        if v not in BACKENDS:
+            raise ValueError(f"backend must be one of {sorted(BACKENDS)}, got {v!r}")
+        return v
+
+    @field_validator("start_method")
+    def _validate_start_method(cls, v: str) -> str:
+        if v not in START_METHODS:
+            raise ValueError(
+                f"start_method must be one of {sorted(START_METHODS)}, got {v!r}"
+            )
+        return v
+
+    @field_validator("compile_mode")
+    def _validate_compile_mode(cls, v: Optional[str]) -> Optional[str]:
+        if v is not None and v not in _COMPILE_MODES:
+            raise ValueError(
+                f"compile_mode must be one of {sorted(_COMPILE_MODES)} or None, got {v!r}"
+            )
+        return v
+
+    @field_validator(
+        "n_epoch",
+        "batch_per_device",
+        "grad_accum_steps",
+        "ckpt_interval",
+        "val_step",
+        "rollout_interval",
+        "rollout_max_tokens",
+    )
+    def _validate_positive_int(cls, v: int) -> int:
+        if v <= 0:
+            raise ValueError(f"must be positive, got {v}")
+        return v
+
+    @field_validator("rollout_temperature")
+    def _validate_positive_float(cls, v: float) -> float:
+        if v <= 0:
+            raise ValueError(f"must be positive, got {v}")
+        return v
+
+    @field_validator("rollout_top_p")
+    def _validate_top_p(cls, v: float) -> float:
+        if not 0 < v <= 1:
+            raise ValueError(f"rollout_top_p must be in (0, 1], got {v}")
+        return v
+
+    @field_validator(
+        "rollout_top_k", "num_workers", "neftune_alpha", "moe_aux_loss_coef"
+    )
+    def _validate_non_negative(cls, v):
+        if v < 0:
+            raise ValueError(f"must be non-negative, got {v}")
+        return v
+
+    @field_validator("max_grad_norm")
+    def _validate_max_grad_norm(cls, v: Optional[float]) -> Optional[float]:
+        if v is not None and v <= 0:
+            raise ValueError(f"max_grad_norm must be positive or None, got {v}")
+        return v
+
+    @field_validator("val_split")
+    def _validate_val_split(cls, v: Optional[float]) -> Optional[float]:
+        if v is not None and not 0 < v < 1:
+            raise ValueError(f"val_split must be in (0, 1) or None, got {v}")
+        return v
+
+    @model_validator(mode="after")
+    def _validate_online_strategy(self) -> "TrainConfig":
+        if self.strategy.startswith("online_") and self.reward_model_fn is None:
+            raise ValueError(
+                f"reward_model_fn is required for online RL strategy {self.strategy!r}"
+            )
+        return self

astrai/dataset/__init__.py

@@ -1,37 +1,37 @@
 from astrai.dataset.dataset import (
     BaseDataset,
     DatasetFactory,
+    dpo_collate_fn,
     grpo_collate_fn,
 )
-from astrai.dataset.sampler import ResumableDistributedSampler
+from astrai.dataset.sampler import RDSampler
 from astrai.dataset.storage import (
-    H5Store,
     JsonlStore,
     MmapStore,
+    Recordable,
     Store,
     StoreFactory,
+    Streamable,
     detect_format,
 )
 from astrai.serialization import (
     load_bin,
-    load_h5,
     save_bin,
-    save_h5,
 )
 
 __all__ = [
     "BaseDataset",
     "DatasetFactory",
+    "dpo_collate_fn",
     "grpo_collate_fn",
     "Store",
+    "Streamable",
+    "Recordable",
     "StoreFactory",
-    "H5Store",
     "MmapStore",
     "JsonlStore",
     "detect_format",
-    "save_h5",
-    "load_h5",
     "save_bin",
     "load_bin",
-    "ResumableDistributedSampler",
+    "RDSampler",
 ]

astrai/dataset/dataset.py

@@ -1,18 +1,213 @@
-"""Dataset implementations with factory pattern for training."""
+"""Dataset implementations for training.
+
+Composition over inheritance — every dataset is a thin wrapper that
+binds a :class:`Store` to a particular train-type's key mapping.  All
+sample-id → token/record indexing lives on the Store; datasets never
+know about window/stride math or segment layouts.
+
+Class hierarchy:
+
+    BaseDataset (ABC)         — holds a Store, exposes __len__/keys,
+                                 overrides __getitem__
+    ├── SEQDataset            — next-token prediction (stream)
+    ├── SFTDataset            — loss-mask + position_ids (stream)
+    ├── DPODataset            — chosen/rejected pairs (record)
+    └── GRPODataset           — prompt + response group (record)
+
+``DatasetFactory.load(train_type, load_path, window_size, stride, …)``
+builds the Store (auto-detecting format) before constructing the
+matching dataset.  Passing ``store=`` skips Store construction.
+
+When a record dataset (DPO) reads from raw JSONL, a *processor*
+function (pure ``record -> Dict[str, Tensor]``) is forwarded to
+:class:`JsonlStore` so tokenisation happens on the fly.
+"""
 
 from abc import ABC, abstractmethod
-from typing import Dict, List, Optional
+from functools import partial
+from pathlib import Path
+from typing import Callable, Dict, List, Optional
 
 import torch
 from torch import Tensor
 from torch.utils.data import Dataset
 
+from astrai.config.preprocess_config import PipelineConfig
 from astrai.dataset.storage import (
     Store,
     StoreFactory,
     detect_format,
 )
 from astrai.factory import BaseFactory
+from astrai.preprocessing.transform import TokenizeTransform
+from astrai.tokenize import AutoTokenizer
+
+_DEFAULT_MESSAGES_CONFIG = {
+    "version": 1,
+    "input": {"sections": [{"field": "messages", "action": "$role", "template": True}]},
+    "mask": {"system": "mask", "user": "mask", "assistant": "train"},
+    "mask_default": "mask",
+    "output": {"position_ids_mode": "doc_reset"},
+}
+
+
+def _build_jsonl_transform(
+    path: str, tokenizer_path: Optional[str] = None
+) -> Optional["TokenizeTransform"]:
+    """Auto-build a TokenizeTransform for JSONL eager loading.
+
+    Reads ``dataset_config.json`` from the data dir if present, or
+    falls back to the built-in chatml SFT config when *tokenizer_path*
+    is provided.
+    """
+    root = Path(path)
+    config_path = root / "dataset_config.json" if root.is_dir() else None
+    if config_path is not None and config_path.exists():
+        return TokenizeTransform.from_config_file(str(config_path))
+    if tokenizer_path:
+        config = PipelineConfig.from_dict(_DEFAULT_MESSAGES_CONFIG)
+        return TokenizeTransform(config, tokenizer_path)
+    return None
+
+
+def dpo_tokenize(
+    record: dict,
+    tokenizer,
+    max_len: int = 2048,
+) -> Optional[dict]:
+    """Tokenize one DPO record into chosen/rejected + masks.
+
+    Applies the tokenizer's chat template so token sequences match the
+    SFT checkpoint's format.  Prompt is rendered with
+    ``add_generation_prompt=True``; chosen/rejected are appended as a
+    single assistant turn.
+
+    Accepts:
+
+    - Flat:   ``{"prompt": str, "chosen": str, "rejected": str}``
+    - Conv:   ``{"prompt": [{role, content}, ...], "chosen": [...], ...}``
+    - Legacy: ``{"input": str, "chosen": str, "rejected": str}``
+
+    No packing, no ``position_ids`` — DPO sequences are independent.
+    """
+    prompt = record.get("prompt") or record.get("input")
+    chosen = record.get("chosen")
+    rejected = record.get("rejected")
+    if prompt is None or chosen is None or rejected is None:
+        return None
+
+    prompt_messages = _to_messages(prompt)
+    chosen_text = _extract_text(chosen)
+    rejected_text = _extract_text(rejected)
+    if chosen_text is None or rejected_text is None:
+        return None
+    chosen_messages = prompt_messages + [{"role": "assistant", "content": chosen_text}]
+    rejected_messages = prompt_messages + [
+        {"role": "assistant", "content": rejected_text}
+    ]
+
+    prompt_ids = tokenizer.apply_chat_template(
+        prompt_messages, tokenize=True, add_generation_prompt=True
+    )
+    ch_ids = tokenizer.apply_chat_template(
+        chosen_messages, tokenize=True, add_generation_prompt=False
+    )
+    re_ids = tokenizer.apply_chat_template(
+        rejected_messages, tokenize=True, add_generation_prompt=False
+    )
+
+    full_ch = ch_ids[:max_len]
+    full_re = re_ids[:max_len]
+
+    prompt_len = min(len(prompt_ids), max_len)
+    ch_mask = [0] * prompt_len + [1] * max(0, len(full_ch) - prompt_len)
+    ch_mask = ch_mask[:max_len]
+    re_mask = [0] * prompt_len + [1] * max(0, len(full_re) - prompt_len)
+    re_mask = re_mask[:max_len]
+
+    return {
+        "chosen": full_ch,
+        "rejected": full_re,
+        "chosen_mask": ch_mask,
+        "rejected_mask": re_mask,
+    }
+
+
+def _to_messages(value) -> list:
+    """Accept str or conversation list; return message list."""
+    if isinstance(value, str):
+        return [{"role": "user", "content": value}]
+    if isinstance(value, list):
+        return value
+    return [{"role": "user", "content": str(value)}]
+
+
+def _extract_text(value) -> Optional[str]:
+    """Accept str or conversation list; return plain text."""
+    if value is None:
+        return None
+    if isinstance(value, str):
+        return value
+    if isinstance(value, list):
+        return "".join(m.get("content", "") for m in value if isinstance(m, dict))
+    return None
+
+
+def dpo_processor(
+    record: dict,
+    tokenizer,
+    max_len: int = 2048,
+) -> Dict[str, Tensor]:
+    """DPO processor: wraps :func:`dpo_tokenize` and returns tensors."""
+    result = dpo_tokenize(record, tokenizer, max_len=max_len)
+    if result is None:
+        raise ValueError(f"Malformed DPO record: {list(record.keys())}")
+    return {
+        "chosen": torch.tensor(result["chosen"], dtype=torch.int32),
+        "rejected": torch.tensor(result["rejected"], dtype=torch.int32),
+        "chosen_mask": torch.tensor(result["chosen_mask"], dtype=torch.bool),
+        "rejected_mask": torch.tensor(result["rejected_mask"], dtype=torch.bool),
+    }
+
+
+def dpo_collate_fn(batch: List[Dict[str, Tensor]]) -> Dict[str, Tensor]:
+    """Collate variable-length DPO samples into padded 2-D tensors.
+
+    Input: list of dicts, each with:
+      - chosen:        [C_i]
+      - rejected:      [R_i]
+      - chosen_mask:   [C_i]
+      - rejected_mask: [R_i]
+
+    Output (padded to the max length across chosen/rejected within the batch):
+      - chosen:        [B, S_max]
+      - rejected:      [B, S_max]
+      - chosen_mask:   [B, S_max]
+      - rejected_mask: [B, S_max]
+    """
+    B = len(batch)
+    S_max = max(b["chosen"].size(0) for b in batch)
+    S_max = max(S_max, max(b["rejected"].size(0) for b in batch))
+
+    chosen = torch.zeros(B, S_max, dtype=torch.long)
+    rejected = torch.zeros(B, S_max, dtype=torch.long)
+    chosen_mask = torch.zeros(B, S_max, dtype=torch.bool)
+    rejected_mask = torch.zeros(B, S_max, dtype=torch.bool)
+
+    for i, b in enumerate(batch):
+        c_len = b["chosen"].size(0)
+        r_len = b["rejected"].size(0)
+        chosen[i, :c_len] = b["chosen"]
+        rejected[i, :r_len] = b["rejected"]
+        chosen_mask[i, :c_len] = b["chosen_mask"]
+        rejected_mask[i, :r_len] = b["rejected_mask"]
+
+    return {
+        "chosen": chosen,
+        "rejected": rejected,
+        "chosen_mask": chosen_mask,
+        "rejected_mask": rejected_mask,
+    }
 
 
 def grpo_collate_fn(batch: List[Dict[str, Tensor]]) -> Dict[str, Tensor]:
@@ -25,7 +220,8 @@ def grpo_collate_fn(batch: List[Dict[str, Tensor]]) -> Dict[str, Tensor]:
       - rewards:  [G]
 
     Output:
-      - prompts:   [B, P_max]
+      - prompts:   [B, P_max], left-padded
+      - prompt_mask: [B, P_max]
       - responses: [B, G, R_max]
       - masks:     [B, G, R_max]
       - rewards:   [B, G]
@@ -36,13 +232,15 @@ def grpo_collate_fn(batch: List[Dict[str, Tensor]]) -> Dict[str, Tensor]:
     R_max = max(r.size(0) for b in batch for r in b["responses"])
 
     prompts = torch.zeros(B, P_max, dtype=torch.long)
+    prompt_mask = torch.zeros(B, P_max, dtype=torch.bool)
     responses = torch.zeros(B, G, R_max, dtype=torch.long)
     masks = torch.zeros(B, G, R_max, dtype=torch.bool)
     rewards = torch.zeros(B, G, dtype=torch.float32)
 
     for i, b in enumerate(batch):
         p_len = b["prompts"].size(0)
-        prompts[i, :p_len] = b["prompts"]
+        prompts[i, -p_len:] = b["prompts"]
+        prompt_mask[i, -p_len:] = True
         rewards[i, : b["rewards"].size(0)] = b["rewards"]
         for g in range(min(G, len(b["responses"]))):
             r_len = b["responses"][g].size(0)
@@ -52,206 +250,220 @@ def grpo_collate_fn(batch: List[Dict[str, Tensor]]) -> Dict[str, Tensor]:
 
     return {
         "prompts": prompts,
+        "prompt_mask": prompt_mask,
         "responses": responses,
         "masks": masks,
         "rewards": rewards,
     }
 
 
-class BaseDataset(Dataset, ABC):
-    """Abstract base class for all dataset types.
+def validate_keys(store: Store, required: List[str]) -> None:
+    """Raise ``KeyError`` if *store* is missing any *required* key."""
+    if not required:
+        return
+    actual = set(store.keys)
+    missing = [k for k in required if k not in actual]
+    if missing:
+        raise KeyError(
+            f"Store at {getattr(store, '_load_path', '?')} is missing required "
+            f"keys {missing}; available keys are {sorted(actual)}."
+        )
 
-    Implements common functionality for window-based data fetching.
-    Uses a storage abstraction for format-agnostic data loading.
+
+class BaseDataset(Dataset, ABC):
+    """Abstract base class for dataset types.
+
+    Holds a :class:`Store`.  All sample-id indexing is delegated to the
+    store — this class exposes ``__len__`` as ``len(store)`` and the
+    ``keys`` property as ``store.keys``.  Subclasses implement
+    ``__getitem__`` with the train-type-specific key mapping and any
+    training-only index arithmetic (e.g. the next-token ``+1`` shift).
     """
 
-    def __init__(self, window_size: int, stride: int):
+    required_keys: List[str] = []
+
+    def __init__(self, store: Store):
         super().__init__()
-        self.window_size = window_size
-        self.stride = stride
-        self.storage: Optional[Store] = None
+        self.store: Store = store
+        validate_keys(store, self.required_keys)
 
-    @property
-    def required_keys(self) -> List[str]:
-        """Return required storage keys for this dataset type.
-
-        Subclasses should override to specify expected keys.
-        """
-        return []
-
-    def _validate_keys(self):
-        if not self.required_keys:
-            return
-        actual_keys = set(self.storage.keys)
-        missing = [k for k in self.required_keys if k not in actual_keys]
-        if missing:
-            raise KeyError(
-                f"Dataset {type(self).__name__} requires keys {self.required_keys}, "
-                f"but storage at {self._load_path} only has {sorted(actual_keys)}. "
-                f"Missing: {missing}"
-            )
-
-    def load(self, load_path: str, storage_type: Optional[str] = None, **kwargs):
-        """Load dataset from the given path.
-
-        Auto-detects the storage format if not specified.
-
-        Args:
-            load_path: Path to the data directory or file
-            storage_type: Force a specific storage type ("h5", "bin", "jsonl"),
-                          or None for auto-detection
-            **kwargs: Extra arguments forwarded to the store constructor and
-                      to ``store.load()``.
-
-        Raises:
-            KeyError: If the loaded storage is missing required keys.
-        """
-        if storage_type is None:
-            storage_type = detect_format(load_path)
-        self.storage = StoreFactory.create(storage_type, **kwargs)
-        self._load_path = load_path
-        self.storage.load(load_path, **kwargs)
-        self._validate_keys()
-
-    @property
-    def count(self) -> int:
-        """Return the total number of raw elements (tokens) in the dataset."""
-        if self.storage is None:
-            return 0
-        return len(self.storage)
+    def __len__(self) -> int:
+        return len(self.store)
 
     @property
     def keys(self) -> List[str]:
-        """Return the available data keys."""
-        if self.storage is None:
-            return []
-        return self.storage.keys
+        return self.store.keys
 
-    def get_index(self, index: int) -> tuple:
-        """Calculate begin and end indices for a sample.
-
-        Args:
-            index: Sample index
-
-        Returns:
-            Tuple of (begin_idx, end_idx)
-        """
-        if self.storage is None:
-            raise RuntimeError("Dataset not loaded, call load() first")
-        total = len(self.storage)
-        if total <= self.window_size:
-            raise ValueError(
-                f"Data too short: {total} tokens <= window_size {self.window_size}"
-            )
-
-        begin_idx = min(index * self.stride, total - 1 - self.window_size)
-        end_idx = min(begin_idx + self.window_size, total - 1)
-
-        return begin_idx, end_idx
+    @property
+    def token_count(self) -> int:
+        return self.store.token_count
 
     @abstractmethod
     def __getitem__(self, index: int) -> Dict[str, Tensor]:
-        """Get a single sample by index.
-
-        Must be implemented by subclasses.
-        """
         raise NotImplementedError
 
-    def __len__(self) -> int:
-        if self.storage is None:
-            return 0
-        total = len(self.storage)
-        if total <= self.window_size:
-            return 0
-        return (total - 1 - self.window_size) // self.stride + 1
-
 
 class DatasetFactory(BaseFactory["BaseDataset"]):
-    """Factory class for creating dataset instances.
+    """Factory for creating dataset instances by train-type.
 
-    Supports decorator-based registration for extensible dataset types.
-    All default dataset types (seq, sft, dpo, grpo) are registered automatically
-    when their classes are defined with the decorator.
-
-    Example usage:
-        @DatasetFactory.register("custom")
-        class CustomDataset(BaseDataset):
-            ...
-
-        dataset = DatasetFactory.create("custom", window_size, stride)
+    Use :meth:`DatasetFactory.register("custom")` to register new
+    dataset classes; they must inherit from :class:`BaseDataset`.
     """
 
     @classmethod
     def load(
         cls,
         train_type: str,
-        load_path: str,
-        window_size: int,
+        load_path: Optional[str] = None,
+        window_size: int = 0,
         stride: Optional[int] = None,
         storage_type: Optional[str] = None,
+        tokenizer_path: Optional[str] = None,
+        max_len: int = 2048,
+        store: Optional[Store] = None,
         **kwargs,
     ) -> "BaseDataset":
         """Create and load a dataset in one step.
 
+        Two entry points:
+
+        - **store given**: bind it directly — the caller fully controls
+          Store construction and processor setup.  *load_path*,
+          *storage_type*, *tokenizer_path*, *window_size*, *stride* are
+          ignored.
+        - **store is None**: build a Store from *load_path*, auto-detecting
+          format and constructing a processor when *tokenizer_path* is
+          given for a record dataset on JSONL.
+
         Args:
-            train_type: Type of training dataset
-            load_path: Path to the data file
-            window_size: Window size for data sampling
-            stride: Stride between consecutive samples (default: same as window_size)
-            storage_type: Storage type ("h5", "bin", "jsonl") or None for auto-detection
-            **kwargs: Extra arguments forwarded to ``dataset.load()``.
+            train_type: Registered dataset name ("seq", "sft", "dpo",
+                "grpo", …).
+            load_path: Path to the data file or directory (ignored if
+                *store* is given).
+            window_size: Stream window length — only meaningful for
+                stream datasets (SEQ/SFT).  Record datasets ignore it.
+            stride: Stride between consecutive stream samples
+                (default: same as *window_size*).
+            storage_type: Storage backend ("bin", "jsonl") or
+                None for auto-detection.
+            tokenizer_path: Path to tokenizer for lazy JSONL
+                tokenisation (record datasets only).
+            max_len: Max sequence length forwarded to processors.
+            store: Pre-built, already-loaded Store instance.
+            **kwargs: Extra arguments forwarded to ``store.load()``.
 
         Returns:
-            Loaded dataset instance
+            Loaded dataset instance.
         """
+        if store is not None:
+            return cls.create(train_type, store=store)
+
+        if load_path is None:
+            raise ValueError("Either load_path or store must be provided")
+
+        if storage_type is None:
+            storage_type = detect_format(load_path)
+
         if stride is None:
             stride = window_size
 
-        dataset = cls.create(train_type, window_size, stride)
-        dataset.load(load_path, storage_type=storage_type, **kwargs)
+        processor = cls._maybe_build_processor(
+            train_type, storage_type, tokenizer_path, max_len
+        )
 
-        return dataset
+        store_window = cls._store_window_for(train_type, window_size)
+        store = StoreFactory.create(
+            storage_type,
+            window_size=store_window,
+            stride=stride if stride else store_window,
+        )
+        if processor is not None:
+            store.load(load_path, processor=processor, **kwargs)
+        elif storage_type == "jsonl":
+            transform = _build_jsonl_transform(load_path, tokenizer_path)
+            if transform is None:
+                raise FileNotFoundError(
+                    "JSONL dataset config not found. Expected "
+                    "dataset_config.json alongside *.jsonl files, pass "
+                    "tokenizer_path= for the built-in messages config, or "
+                    "use processor= for lazy on-the-fly tokenisation."
+                )
+            store.load(load_path, transform=transform, **kwargs)
+        else:
+            store.load(load_path, **kwargs)
+
+        return cls.create(train_type, store=store)
+
+    @staticmethod
+    def _store_window_for(train_type: str, window_size: int) -> int:
+        """Stream datasets consume ``window_size``; record datasets ignore it.
+
+        Record datasets (dpo/grpo) treat each record as an independent
+        training unit and never window, so the store is built with
+        ``window_size=0`` and ``len(store)`` returns the record count.
+        """
+        if train_type in ("seq", "sft"):
+            return window_size
+        return 0
+
+    @staticmethod
+    def _maybe_build_processor(
+        train_type: str,
+        storage_type: str,
+        tokenizer_path: Optional[str],
+        max_len: int,
+    ) -> Optional[Callable[[dict], Dict[str, Tensor]]]:
+        """Build an on-the-fly tokenisation processor if applicable.
+
+        Only raw JSONL + record datasets (DPO/GRPO) need a processor;
+        pre-tokenised backends (bin) and stream datasets (SEQ/SFT)
+        return ``None`` so no tokenizer is loaded.
+        """
+        if tokenizer_path is None or storage_type != "jsonl":
+            return None
+        if train_type == "dpo":
+            tokenizer = AutoTokenizer.from_pretrained(tokenizer_path)
+            return partial(dpo_processor, tokenizer=tokenizer, max_len=max_len)
+        return None
 
 
 @DatasetFactory.register("seq")
 class SEQDataset(BaseDataset):
-    """Dataset for sequential next-token prediction training."""
+    """Dataset for sequential next-token prediction training.
 
-    @property
-    def required_keys(self) -> List[str]:
-        return ["sequence"]
+    Stream mode: ``store.fetch(begin, end, "sequence")`` returns the
+    input window; the +1 shifted call returns the next-token target.
+    """
 
-    def _fetch_data(self, begin_idx: int, end_idx: int) -> Tensor:
-        return self.storage.fetch(begin_idx, end_idx, "sequence")
+    required_keys = ["sequence"]
 
-    def __getitem__(self, index):
-        begin_idx, end_idx = self.get_index(index)
-
-        x = self._fetch_data(begin_idx, end_idx).to(dtype=torch.long)
-        y = self._fetch_data(begin_idx + 1, end_idx + 1).to(dtype=torch.long)
-
-        return {"input_ids": x, "target_ids": y}
+    def __getitem__(self, index: int):
+        begin, end = self.store.sample_window(index)
+        x = self.store.fetch(begin, end, "sequence")
+        y = self.store.fetch(begin + 1, end + 1, "sequence")
+        return {
+            "input_ids": x.to(dtype=torch.long),
+            "target_ids": y.to(dtype=torch.long),
+        }
 
 
 @DatasetFactory.register("sft")
 class SFTDataset(BaseDataset):
-    """Dataset for supervised fine-tuning with loss masking."""
+    """Dataset for supervised fine-tuning with loss masking.
 
-    @property
-    def required_keys(self) -> List[str]:
-        return ["sequence", "loss_mask", "position_ids"]
+    Stream mode: ``sequence``/``loss_mask``/``position_ids`` are sliced
+    to the window.  ``loss_mask`` and ``target_ids`` use the +1 shifted
+    slice so they align with the predicted positions.
+    """
 
-    def _fetch_data(self, begin_idx: int, end_idx: int, key: str) -> Tensor:
-        return self.storage.fetch(begin_idx, end_idx, key)
-
-    def __getitem__(self, index):
-        begin_idx, end_idx = self.get_index(index)
-
-        x = self._fetch_data(begin_idx, end_idx, "sequence")
-        y = self._fetch_data(begin_idx + 1, end_idx + 1, "sequence")
-        position_ids = self._fetch_data(begin_idx, end_idx, "position_ids")
-        loss_mask = self._fetch_data(begin_idx + 1, end_idx + 1, "loss_mask")
+    required_keys = ["sequence", "loss_mask", "position_ids"]
 
+    def __getitem__(self, index: int):
+        begin, end = self.store.sample_window(index)
+        x = self.store.fetch(begin, end, "sequence")
+        y = self.store.fetch(begin + 1, end + 1, "sequence")
+        position_ids = self.store.fetch(begin, end, "position_ids")
+        loss_mask = self.store.fetch(begin + 1, end + 1, "loss_mask")
         return {
             "input_ids": x.to(dtype=torch.long),
             "target_ids": y.to(dtype=torch.long),
@@ -262,32 +474,34 @@ class SFTDataset(BaseDataset):
 
 @DatasetFactory.register("dpo")
 class DPODataset(BaseDataset):
-    """Dataset for Direct Preference Optimization training."""
+    """Record-structured dataset for Direct Preference Optimization.
 
-    @property
-    def required_keys(self) -> List[str]:
-        return ["chosen", "rejected", "chosen_mask", "rejected_mask"]
+    Each sample is one preference pair (chosen + rejected) and is an
+    independent training unit — no windowing, stride, or cross-record
+    concatenation.  This keeps each sequence self-contained so attention
+    never leaks across preference pairs.
 
-    def _fetch_data(self, begin_idx: int, end_idx: int, key: str) -> Tensor:
-        return self.storage.fetch(begin_idx, end_idx, key)
+    Two loading paths (handled by :class:`DatasetFactory`):
 
-    def __getitem__(self, index: int):
-        begin_idx, end_idx = self.get_index(index)
+    - **Pre-tokenized** (bin): ``store.load(path)`` reads per-record
+      tensors; ``__getitem__`` returns them directly.
+    - **Raw JSONL** (``tokenizer_path=...``): builds a lazy processor
+      via :func:`dpo_processor` that tokenises on the fly — no packing,
+      no ``position_ids``.
+    """
 
-        chosen = self._fetch_data(begin_idx, end_idx, "chosen").to(dtype=torch.long)
-        rejected = self._fetch_data(begin_idx, end_idx, "rejected").to(dtype=torch.long)
-        chosen_mask = self._fetch_data(begin_idx, end_idx, "chosen_mask").to(
-            dtype=torch.bool
-        )
-        rejected_mask = self._fetch_data(begin_idx, end_idx, "rejected_mask").to(
-            dtype=torch.bool
-        )
+    required_keys = ["chosen", "rejected", "chosen_mask", "rejected_mask"]
 
+    def __getitem__(self, index: int) -> Dict[str, Tensor]:
         return {
-            "chosen": chosen,
-            "rejected": rejected,
-            "chosen_mask": chosen_mask,
-            "rejected_mask": rejected_mask,
+            "chosen": self.store.fetch_record(index, "chosen").to(dtype=torch.long),
+            "rejected": self.store.fetch_record(index, "rejected").to(dtype=torch.long),
+            "chosen_mask": self.store.fetch_record(index, "chosen_mask").to(
+                dtype=torch.bool
+            ),
+            "rejected_mask": self.store.fetch_record(index, "rejected_mask").to(
+                dtype=torch.bool
+            ),
         }
 
 
@@ -295,10 +509,8 @@ class DPODataset(BaseDataset):
 class GRPODataset(BaseDataset):
     """Dataset for offline Group Relative Policy Optimization.
 
-    Unlike the window-based datasets (SEQ/SFT/DPO), GRPO data is
-    record-structured: each sample is one prompt with its group of
-    responses and scalar rewards.  There is no windowing or stride —
-    every record is an independent training unit.
+    Each sample is one prompt with its group of responses and scalar
+    rewards — an independent training unit with no windowing or stride.
 
     Expected storage layout (produced by JsonlStore or pre-tokenized):
 
@@ -308,70 +520,16 @@ class GRPODataset(BaseDataset):
     - ``rewards``:   List[Tensor]  — one 1-D float tensor (len G) per record
     """
 
-    def __init__(self, window_size: int = 0, stride: int = 0, **kwargs):
-        super().__init__(window_size=window_size, stride=stride or window_size)
-        self._records: List[dict] = []
-
-    @property
-    def required_keys(self) -> List[str]:
-        return ["prompts", "responses", "masks", "rewards"]
-
-    def load(self, load_path: str, storage_type: Optional[str] = None, **kwargs):
-        if storage_type is None:
-            storage_type = detect_format(load_path)
-        self.storage = StoreFactory.create(storage_type, **kwargs)
-        self._load_path = load_path
-        self.storage.load(load_path, **kwargs)
-        self._validate_keys()
-        self._build_records()
-
-    def _validate_keys(self):
-        actual_keys = set(self.storage.keys)
-        missing = [k for k in self.required_keys if k not in actual_keys]
-        if missing:
-            raise KeyError(
-                f"GRPODataset requires keys {self.required_keys}, "
-                f"but storage only has {sorted(actual_keys)}. Missing: {missing}"
-            )
-
-    def _build_records(self):
-        """Unfold segmented storage into per-record lists.
-
-        ``prompts`` is a flat list of 1-D tensors (one per record).
-        ``responses`` / ``masks`` are nested lists (G tensors per record).
-        ``rewards`` is a flat list of 1-D tensors (len G per record).
-        """
-        prompt_segs = self.storage._data.get("prompts", [])
-        response_segs = self.storage._data.get("responses", [])
-        mask_segs = self.storage._data.get("masks", [])
-        reward_segs = self.storage._data.get("rewards", [])
-
-        n_records = len(prompt_segs)
-        self._records = []
-        for i in range(n_records):
-            self._records.append(
-                {
-                    "prompts": prompt_segs[i],
-                    "responses": response_segs[i] if i < len(response_segs) else [],
-                    "masks": mask_segs[i] if i < len(mask_segs) else [],
-                    "rewards": reward_segs[i]
-                    if i < len(reward_segs)
-                    else torch.tensor([]),
-                }
-            )
-
-    @property
-    def count(self) -> int:
-        return len(self._records)
-
-    def __len__(self) -> int:
-        return len(self._records)
+    required_keys = ["prompts", "responses", "masks", "rewards"]
 
     def __getitem__(self, index: int) -> Dict[str, Tensor]:
-        rec = self._records[index]
+        prompts = self.store.fetch_record(index, "prompts")
+        responses = self.store.fetch_record(index, "responses")
+        masks = self.store.fetch_record(index, "masks")
+        rewards = self.store.fetch_record(index, "rewards")
         return {
-            "prompts": rec["prompts"].to(dtype=torch.long),
-            "responses": [r.to(dtype=torch.long) for r in rec["responses"]],
-            "masks": [m.to(dtype=torch.bool) for m in rec["masks"]],
-            "rewards": rec["rewards"].to(dtype=torch.float32),
+            "prompts": prompts.to(dtype=torch.long),
+            "responses": [r.to(dtype=torch.long) for r in responses],
+            "masks": [m.to(dtype=torch.bool) for m in masks],
+            "rewards": rewards.to(dtype=torch.float32),
         }

astrai/dataset/sampler.py

@@ -5,7 +5,15 @@ import torch.distributed as dist
 from torch.utils.data import Dataset, Sampler
 
 
-class ResumableDistributedSampler(Sampler[int]):
+class RDSampler(Sampler[int]):
+    """Resumable Distributed Sampler.
+
+    A distributed sampler that supports checkpoint-based resume: iteration
+    state (epoch, position) is tracked so training can continue from the
+    exact sample after a restart.  Shards the dataset across
+    ``dist.world_size`` replicas with optional shuffling.
+    """
+
     def __init__(
         self,
         data_source: Dataset,

astrai/dataset/storage.py

@@ -1,20 +1,47 @@
 """Storage backends for different data formats.
 
-Layers:
-  - I/O layer:       save_* / load_* functions, read/write raw files (HDF5/bin)
-                      return Dict[str, List[Tensor]] — format-specific, no state
-  - Store (ABC):     central abstraction, normalizes multi-segment into
-                      Dict[str, List[Tensor]] per key via _normalize(),
-                      fetch() uses bisect across segments — no forced concat
-  - Dataset layer:   BaseDataset owns a Store, only calls store.fetch(begin, end, key)
+Architecture (composition over inheritance):
 
-Key properties:
-  - Multi-segment:   segments kept as-is, no forced concatenation — safe for
-                      datasets larger than RAM
-  - Explicit length: _length = min(total elements across keys), set at load,
-                      __len__ returns O(1)
-  - Zero-copy mmap:  MmapStore wraps np.memmap(mode="r"), all DataLoader
-                       workers share OS page-cache pages
+    Store (ABC)               — owns _data/_cum/_offsets bookkeeping
+                                  + window_size/stride for sample-id
+                                  indexing.  __getitem__/__len__ produce
+                                  the smallest iterable unit so Dataset
+                                  classes are pure delegators.
+    Streamable (mixin)        — raw token slice  fetch(begin, end, keys)
+    Recordable (mixin)        — raw record slice fetch_record(idx, keys)
+
+    MmapStore(Store, Streamable, Recordable)
+    JsonlStore(Store, Streamable, Recordable)
+
+Each mixin is a stateless trait that relies on ``self._data`` etc.
+provided by :class:`Store`.  Concrete stores mix in whichever access
+primitives they support — ``Store`` is the sole base class, so there is
+no diamond inheritance or MRO ambiguity.
+
+Sample-id indexing lives on :class:`Store`, not on the dataset:
+
+- **Stream mode** (``window_size > 0``):  ``len(store)`` returns the number
+  of ``(window_size, stride)`` windows that fit in the token river;
+  ``store[i]`` returns the *i*-th window as a dict of per-key tensors;
+  ``store.sample_window(i)`` exposes the underlying ``(begin, end)``
+  token slice for callers (e.g. next-token trainers) that need a +1
+  shifted companion window.
+- **Record mode** (``num_records > 0``):  ``len(store)`` returns the
+  record count; ``store[i]`` returns the *i*-th record dict.
+
+Raw token/record access via :meth:`fetch` / :meth:`fetch_record`
+remains available for low-level callers that want explicit index
+control.  ``store.token_count`` is the total stream token count (what
+``len(store)`` used to mean in the legacy stream-only API).
+
+``segments_are_records`` (class attribute on each Store subclass)
+tells ``_normalize`` whether segments are inherently per-record (JSONL)
+or opaque shards (bin).  Record access for bin relies on ``_offsets``
+instead.
+
+:class:`JsonlStore` supports a lazy mode (``processor=fn``) that keeps
+raw records and defers tokenisation to ``fetch_record`` — used by DPO
+to train directly from a ``.jsonl`` file without a pre-tokenised copy.
 """
 
 import bisect
@@ -23,20 +50,16 @@ import json
 import logging
 from abc import ABC, abstractmethod
 from pathlib import Path
-from typing import Dict, List, Union
+from typing import Callable, Dict, List, Optional, Tuple, Union
 
 import torch
 from torch import Tensor
 
-from astrai.config.preprocess_config import PipelineConfig
 from astrai.factory import BaseFactory
-from astrai.preprocessing.builder import MaskBuilderFactory
-from astrai.preprocessing.position_id import PositionIdStrategyFactory
 from astrai.serialization import (
     load_bin,
-    load_h5,
+    load_bin_offsets,
 )
-from astrai.tokenize import AutoTokenizer
 
 logger = logging.getLogger(__name__)
 
@@ -48,7 +71,7 @@ def detect_format(load_path: str) -> str:
         load_path: Directory or file path
 
     Returns:
-        Format string ("h5", "bin", or "jsonl")
+        Format string ("h5", "bin", "jsonl", or "processed")
 
     Raises:
         FileNotFoundError: If no supported data files are found
@@ -56,19 +79,10 @@ def detect_format(load_path: str) -> str:
     root = Path(load_path)
     if root.is_file():
         suffix = root.suffix.lower()
-        if suffix in (".h5", ".hdf5"):
-            return "h5"
         if suffix == ".jsonl":
             return "jsonl"
         raise ValueError(f"Unsupported file format: {suffix}")
 
-    h5_files = [
-        Path(p)
-        for pattern in ("*.h5", "*.hdf5")
-        for p in glob.glob(str(root / "**" / pattern), recursive=True)
-    ]
-    if h5_files:
-        return "h5"
     bin_files = [Path(p) for p in glob.glob(str(root / "**" / "*.bin"), recursive=True)]
     if bin_files:
         has_meta = (root / "meta.json").exists() or len(
@@ -81,84 +95,173 @@ def detect_format(load_path: str) -> str:
     ]
     if jsonl_files:
         return "jsonl"
-    json_files = [
-        Path(p) for p in glob.glob(str(root / "**" / "*.json"), recursive=True)
-    ]
-    if json_files:
-        return "jsonl"
     raise FileNotFoundError(f"No supported data files found at {load_path}")
 
 
 class Store(ABC):
-    """String keys -> segmented tensors with ``fetch(begin, end, keys)``.
+    """Common base for all storage backends.
 
-    Each key maps to one or more tensor segments (no forced concatenation).
-    ``len(store)`` returns ``self._length`` (explicit, O(1)), the minimum
-    total element count across all keys.
+    A Store owns both its data layout AND its sample-id → token/record
+    index translation.  Datasets are thin wrappers that bind a Store
+    to a particular train-type's key mapping; they never know about
+    window/stride math.
 
-    Subclasses fill ``self._data`` and ``self._cum`` during ``load()``
-    via ``_normalize()``.
+    Two iteration modes:
+
+    - **Stream** (``window_size > 0``): data is treated as one long
+      token river.  ``len(store)`` returns the number of windows;
+      ``store[i]`` slices every stream-compatible key to window ``i``;
+      ``store.sample_window(i)`` returns the ``(begin, end)`` token
+      slice for callers needing a +1 shifted companion window.
+    - **Record** (``num_records > 0``): data is per-record.
+      ``len(store)`` returns ``num_records``; ``store[i]`` returns
+      the *i*-th record as a dict.
+
+    Raw token slicing is still available via :meth:`fetch` (mixed in
+    by :class:`Streamable`) when a store has stream support configured.
+    Raw record slicing via :meth:`fetch_record` (mixed in by
+    :class:`Recordable`) when a store has record support.
+
+    ``token_count`` exposes the raw total stream length — this is what
+    ``len(store)`` returned in the legacy stream-only API and what
+    stream-bound ``fetch`` uses for its bounds check.
     """
 
-    def __init__(self):
+    segments_are_records: bool = False
+
+    def __init__(
+        self,
+        window_size: int = 0,
+        stride: Optional[int] = None,
+    ):
         self._data: Dict[str, List[Tensor]] = {}
         self._cum: Dict[str, List[int]] = {}
+        self._offsets: Dict[str, List[int]] = {}
         self._length: int = 0
+        self._num_records: int = 0
+        self._window_size: int = int(window_size)
+        self._stride: int = int(stride) if stride is not None else int(window_size)
 
     @abstractmethod
-    def load(self, path: str) -> None:
+    def load(self, path: str, **kwargs) -> None:
         raise NotImplementedError
 
     @property
     def keys(self) -> List[str]:
         return list(self._data.keys())
 
-    def __len__(self) -> int:
+    @property
+    def window_size(self) -> int:
+        return self._window_size
+
+    @property
+    def stride(self) -> int:
+        return self._stride
+
+    @property
+    def token_count(self) -> int:
+        """Total tokens across all stream segments.
+
+        Useful for the bounds-checked raw :meth:`fetch` and as the
+        legacy ``len(store)`` value.
+        """
         return self._length
 
-    def fetch(
-        self,
-        begin: int,
-        end: int,
-        keys: Union[str, List[str]],
-    ):
-        if not self._data:
-            raise RuntimeError("Store not loaded")
-        if not (0 <= begin < self._length and 0 <= end <= self._length):
-            raise ValueError(
-                f"Index out of bounds: begin={begin}, end={end}, length={self._length}"
+    @property
+    def num_records(self) -> int:
+        """Number of records available via :meth:`fetch_record`.
+
+        Non-zero only when the backing layout provides per-record
+        indexing (JSONL segments or bin ``_offsets``).
+        """
+        return self._num_records
+
+    @property
+    def num_samples(self) -> int:
+        """Number of items produced by ``__getitem__``.
+
+        Stream-mode wins when ``window_size > 0`` and there are tokens
+        to slice; otherwise falls back to ``num_records``.
+        """
+        if self._window_size > 0 and self._length > 0:
+            total = self._length
+            w = self._window_size
+            if total <= w:
+                return 0
+            return (total - 1 - w) // self._stride + 1
+        return self._num_records
+
+    def __len__(self) -> int:
+        return self.num_samples
+
+    def __getitem__(self, index: int) -> Dict[str, Tensor]:
+        if index < 0:
+            index += self.num_samples
+        if not 0 <= index < self.num_samples:
+            raise IndexError(
+                f"Store index out of range: {index}, num_samples={self.num_samples}"
             )
-        if isinstance(keys, str):
-            return self._fetch_key(keys, begin, end)
-        return {k: self._fetch_key(k, begin, end) for k in keys}
+        if self._window_size > 0 and self._length > 0:
+            begin, end = self.sample_window(index)
+            keys = self._stream_keys()
+            return {k: self.fetch(begin, end, k) for k in keys}
+        return self.fetch_record(index, self._record_keys())
 
-    def _fetch_key(self, key: str, begin: int, end: int) -> Tensor:
-        """Fetch slice [begin, end) across potentially multiple segments."""
-        segments = self._data[key]
-        cum = self._cum[key]
-        seg_start = bisect.bisect_right(cum, begin)
-        seg_end = bisect.bisect_left(cum, end)
+    def sample_window(self, index: int) -> Tuple[int, int]:
+        """Return ``(begin, end)`` token positions for stream sample *index*.
 
-        results = []
-        for i in range(seg_start, seg_end + 1):
-            prev = cum[i - 1] if i > 0 else 0
-            s = max(begin - prev, 0)
-            e = min(end - prev, segments[i].shape[0])
-            results.append(segments[i][s:e])
+        The clipped tail keeps the last reachable window inside the
+        token river instead of overshooting.  Caller is responsible
+        for staying within :attr:`num_samples`: an out-of-range index
+        raises ``IndexError``.
+        """
+        if self._window_size <= 0:
+            raise RuntimeError("sample_window() requires window_size > 0 (stream mode)")
+        if self._length <= self._window_size:
+            raise IndexError(
+                f"Data too short for window: token_count={self._length}, "
+                f"window_size={self._window_size}"
+            )
+        if not 0 <= index < self.num_samples:
+            raise IndexError(
+                f"Sample index out of range: {index}, num_samples={self.num_samples}"
+            )
+        total = self._length
+        begin = min(index * self._stride, total - 1 - self._window_size)
+        end = min(begin + self._window_size, total - 1)
+        return begin, end
 
-        return results[0] if len(results) == 1 else torch.cat(results, dim=0)
+    def _stream_keys(self) -> List[str]:
+        out: List[str] = []
+        for k, tensors in self._data.items():
+            if tensors and isinstance(tensors[0], list):
+                continue
+            out.append(k)
+        return out
 
-    def _normalize(self, raw: Dict[str, list]):
-        """Register segments and pre-compute cumulative lengths.
+    def _record_keys(self) -> List[str]:
+        return list(self._data.keys())
 
-        Does NOT concatenate — segments are kept as-is to avoid OOM on
-        large datasets.  Sets ``self._length`` to the minimum total
-        element count across all flat-tensor keys.
+    def _normalize(
+        self,
+        raw: Dict[str, list],
+        offsets: Optional[Dict[str, List[int]]] = None,
+    ):
+        """Register segments and pre-compute indices for both access modes.
 
-        For GRPO multi-response keys, values may be ``List[List[Tensor]]``
-        (one list of G tensors per record).  These are stored as-is and
-        excluded from the cumulative-length bookkeeping since they are
-        accessed record-by-record via ``_data`` rather than via ``fetch``.
+        Stream mode: ``_cum[key]`` accumulates per-segment lengths so
+        ``Streamable._fetch_stream_key`` can bisect across segments
+        without concatenation.
+
+        Record mode: if *offsets* is provided (bin layout),
+        ``_offsets[key]`` stores cumulative per-record offsets into the
+        single concatenated segment.  Otherwise, when
+        ``segments_are_records`` is True (JSONL), ``_data[key]`` is
+        a per-record list and ``fetch_record`` indexes it directly.
+
+        Nested keys (GRPO ``responses``/``masks`` as
+        ``List[List[Tensor]]``) are stored as-is and excluded from both
+        cumulative bookkeepings — they are only accessed record-by-record.
         """
         flat_lengths = []
         for key, tensors in raw.items():
@@ -167,7 +270,6 @@ class Store(ABC):
                 self._cum[key] = []
                 flat_lengths.append(0)
                 continue
-            # Skip nested lists (GRPO responses/masks) — record-level access
             if isinstance(tensors[0], list):
                 self._cum[key] = []
                 continue
@@ -180,166 +282,320 @@ class Store(ABC):
             flat_lengths.append(cum[-1] if cum else 0)
         self._length = min(flat_lengths) if flat_lengths else 0
 
+        valid_offsets: Dict[str, List[int]] = {}
+        if offsets:
+            for key, off in offsets.items():
+                segs = self._data.get(key, [])
+                if len(segs) == 1 and len(off) > 1:
+                    valid_offsets[key] = off
+                elif len(segs) > 1:
+                    logger.warning(
+                        "Key '%s' has %d segments with offsets — record mode "
+                        "disabled for this key (multi-shard bin+offsets not "
+                        "supported). Merge shards or use JSONL.",
+                        key,
+                        len(segs),
+                    )
+        self._offsets = valid_offsets
+        if valid_offsets:
+            record_counts = [len(v) - 1 for v in valid_offsets.values()]
+            self._num_records = min(record_counts) if record_counts else 0
+        elif self.segments_are_records:
+            per_record_counts = []
+            for key, tensors in self._data.items():
+                if tensors and isinstance(tensors[0], list):
+                    continue
+                per_record_counts.append(len(tensors))
+            self._num_records = min(per_record_counts) if per_record_counts else 0
+        else:
+            self._num_records = 0
 
-class StoreFactory(BaseFactory["Store"]):
-    """Factory for creating Store instances by type name.
 
-    Example::
+class Streamable:
+    """Mixin granting raw token-stream access via :meth:`fetch`.
 
-        @StoreFactory.register("custom")
-        class CustomStore(Store):
-            ...
+    Stateless trait relying on ``self._data``, ``self._cum``,
+    ``self._length`` maintained by :class:`Store`.  Stream mode is
+    active when the owning store has ``window_size > 0``; for stores
+    that can also serve record access (JSONL/bin+offsets), the
+    ``fetch_record`` API from :class:`Recordable` is used instead.
     """
 
+    def fetch(
+        self,
+        begin: int,
+        end: int,
+        keys: Union[str, List[str]],
+    ):
+        return _stream_fetch(self, begin, end, keys)
 
-@StoreFactory.register("h5")
-class H5Store(Store):
-    """HDF5-based storage backend (pre-tokenized data)."""
 
-    def load(self, path: str):
-        self._normalize(load_h5(path))
+def _stream_fetch(self, begin: int, end: int, keys: Union[str, List[str]]):
+    if not getattr(self, "_data", None):
+        raise RuntimeError("Store not loaded")
+    if not (0 <= begin < self._length and 0 <= end <= self._length):
+        raise ValueError(
+            f"Index out of bounds: begin={begin}, end={end}, length={self._length}"
+        )
+    if isinstance(keys, str):
+        return _fetch_stream_key(self, keys, begin, end)
+    return {k: _fetch_stream_key(self, k, begin, end) for k in keys}
+
+
+def _fetch_stream_key(self, key: str, begin: int, end: int) -> Tensor:
+    segments = self._data[key]
+    cum = self._cum[key]
+    seg_start = bisect.bisect_right(cum, begin)
+    seg_end = bisect.bisect_left(cum, end)
+
+    results = []
+    for i in range(seg_start, seg_end + 1):
+        prev = cum[i - 1] if i > 0 else 0
+        s = max(begin - prev, 0)
+        e = min(end - prev, segments[i].shape[0])
+        results.append(segments[i][s:e])
+
+    return results[0] if len(results) == 1 else torch.cat(results, dim=0)
+
+
+class Recordable:
+    """Mixin granting raw record access via :meth:`fetch_record`.
+
+    Stateless trait relying on ``self._data``, ``self._offsets``,
+    ``self._num_records`` maintained by :class:`Store`.
+    """
+
+    def fetch_record(
+        self,
+        index: int,
+        keys: Union[str, List[str]],
+    ):
+        return _record_fetch(self, index, keys)
+
+
+def _record_fetch(self, index: int, keys: Union[str, List[str]]):
+    if not getattr(self, "_data", None) and self._num_records == 0:
+        raise RuntimeError("Store not loaded")
+    if not 0 <= index < self._num_records:
+        raise ValueError(
+            f"Record index out of bounds: {index}, num_records={self._num_records}"
+        )
+    if isinstance(keys, str):
+        return _fetch_record_key(self, keys, index)
+    return {k: _fetch_record_key(self, k, index) for k in keys}
+
+
+def _fetch_record_key(self, key: str, index: int):
+    offsets = self._offsets.get(key)
+    if offsets:
+        start = offsets[index]
+        end = (
+            offsets[index + 1]
+            if index + 1 < len(offsets)
+            else self._data[key][0].shape[0]
+        )
+        return self._data[key][0][start:end]
+    return self._data[key][index]
+
+
+class StoreFactory(BaseFactory["Store"]):
+    """Factory for creating Store instances by type name."""
 
 
 @StoreFactory.register("bin")
-class MmapStore(Store):
+class MmapStore(Store, Streamable, Recordable):
     """Memory-mapped binary storage backend.
 
     Each key is a single .bin file backed by ``np.memmap(mode="r")``.
     No per-process memory duplication — all DataLoader workers share the
     same OS page-cache pages.
 
-    Format on disk::
+    Supports both access modes:
 
-        data_root/
-          meta.json          # {key: {shape, dtype}, ...}
-          <key>.bin          # raw numpy array, one per key
+    - **Stream**: always available via :meth:`fetch`.
+    - **Record** (``fetch_record(i, key)``): only when ``meta.json``
+      contains per-record ``offsets`` (written via
+      ``save_bin(..., record_keys=...)``).  Legacy bin files without
+      offsets have ``num_records == 0`` and ``len(store)`` reflects the
+      windowed sample count when ``window_size > 0``.
+
+    ``segments_are_records`` is ``False`` here (bin segments are
+    contiguous streams, not per-record) — record access is driven
+    purely by ``_offsets``.
     """
 
-    def load(self, path: str):
+    segments_are_records = False
+
+    def __init__(
+        self,
+        window_size: int = 0,
+        stride: Optional[int] = None,
+    ):
+        super().__init__(window_size=window_size, stride=stride)
+        self._mmap_refs: List[Tensor] = []
+
+    def load(self, path: str, **kwargs):
         self._mmap_refs = []
         root = Path(path)
         all_raw: Dict[str, List[Tensor]] = {}
+        all_offsets: Dict[str, List[int]] = {}
         meta_paths = [
             Path(p) for p in glob.glob(str(root / "**" / "meta.json"), recursive=True)
         ]
         for meta_path in meta_paths:
             raw = load_bin(str(meta_path.parent))
+            off = load_bin_offsets(str(meta_path.parent))
             for key, tensors in raw.items():
                 if key not in all_raw:
                     all_raw[key] = []
                 all_raw[key].extend(tensors)
+            for key, o in off.items():
+                if key not in all_offsets:
+                    all_offsets[key] = []
+                all_offsets[key].extend(o)
         if not meta_paths:
             raise FileNotFoundError(f"No meta.json found under {path}")
-        self._normalize(all_raw)
+        self._normalize(all_raw, offsets=all_offsets or None)
         for tensors in self._data.values():
             self._mmap_refs.extend(tensors)
 
 
-@StoreFactory.register("jsonl")
-class JsonlStore(Store):
-    """On-the-fly tokenization store for raw JSONL files.
+class JsonlSource:
+    """Read raw JSON records from a ``.jsonl`` file or directory.
 
-    A JSONL dataset directory contains ``*.jsonl`` files plus a
-    ``dataset_config.json`` file that follows the same schema as
-    :class:`PipelineConfig` with an additional ``tokenizer_path`` field.
-    Records are tokenized when the store is loaded and concatenated into
-    segmented tensors matching the key layout expected by the dataset
-    classes (``sequence``, ``loss_mask``, ``position_ids``, ...).
+    A thin reader used by :class:`JsonlStore` in processor mode — holds
+    no tokenizer, performs no tokenisation, just yields dicts.
     """
 
-    CONFIG_NAME = "dataset_config.json"
+    def __init__(self, path: str):
+        self.path = Path(path)
+        self._records: Optional[List[dict]] = None
 
-    def load(self, path: str):
-        root = Path(path)
-        config_path = root / self.CONFIG_NAME
-        if not config_path.exists():
-            raise FileNotFoundError(
-                f"JSONL dataset config not found: {config_path}. "
-                f"Expected {self.CONFIG_NAME} alongside *.jsonl files."
+    def load(self) -> List[dict]:
+        if self._records is None:
+            self._records = self._read(self.path)
+        return self._records
+
+    @staticmethod
+    def _read(root: Path) -> List[dict]:
+        if root.is_file():
+            return JsonlSource._read_file(root)
+        return JsonlSource._read_dir(root)
+
+    @staticmethod
+    def _read_file(path: Path) -> List[dict]:
+        records: List[dict] = []
+        with open(path, "r", encoding="utf-8") as f:
+            for line in f:
+                line = line.strip()
+                if not line:
+                    continue
+                try:
+                    records.append(json.loads(line))
+                except json.JSONDecodeError:
+                    logger.warning("Failed to parse JSON line in %s, skipping", path)
+        return records
+
+    @staticmethod
+    def _read_dir(root: Path) -> List[dict]:
+        records: List[dict] = []
+        for jsonl_path in sorted(root.glob("*.jsonl")):
+            records.extend(JsonlSource._read_file(jsonl_path))
+        return records
+
+
+@StoreFactory.register("jsonl")
+class JsonlStore(Store, Streamable, Recordable):
+    """JSONL reader with eager/lazy tokenisation modes.
+
+    A JSONL dataset is a ``.jsonl`` file or a directory of ``*.jsonl``
+    files plus (optionally) a ``dataset_config.json`` describing the
+    tokenization pipeline.
+
+    Three ways to supply an eager transform (first match wins):
+
+    - **Explicit** (``transform=``): caller-built
+      :class:`TokenizeTransform` applied eagerly.
+    - **Config file**: ``dataset_config.json`` alongside the ``*.jsonl``
+      files — loaded via :meth:`TokenizeTransform.from_config_file`.
+    - **Default messages** (``tokenizer_path=`` given, no config file):
+      a built-in chatml config that tokenises the ``messages`` field,
+      masking every role except ``assistant`` (loss on assistant only).
+      Lets SFT/SEQ train straight from a chat-style JSONL directory
+      without a hand-written config.
+
+    Two tokenisation modes, selected at :meth:`load` time:
+
+    - **Eager** (default): applies the transform to every record at load
+      time and registers per-key tensors via ``_normalize``.  Both
+      ``fetch`` (stream) and ``fetch_record`` (record) work.
+    - **Lazy** (``processor=fn`` passed): keeps raw records and defers
+      tokenisation to ``fetch_record``.  Only record access works —
+      ``len(store)`` returns ``num_records``; stream primitives raise.
+    """
+
+    segments_are_records = True
+
+    def __init__(
+        self,
+        window_size: int = 0,
+        stride: Optional[int] = None,
+    ):
+        super().__init__(window_size=window_size, stride=stride)
+        self._source: Optional[JsonlSource] = None
+        self._processor: Optional[Callable[[dict], Dict[str, Tensor]]] = None
+        self._keys_cache: Optional[List[str]] = None
+
+    def load(self, path: str, transform=None, processor=None, **kwargs):
+        self._source = JsonlSource(path)
+        records = self._source.load()
+
+        if processor is not None:
+            self._processor = processor
+            self._num_records = len(records)
+            return
+
+        if transform is None:
+            raise ValueError(
+                "JsonlStore eager mode requires transform=. "
+                "Use DatasetFactory.load() which auto-constructs it."
             )
 
-        with open(config_path, "r", encoding="utf-8") as f:
-            raw_config = json.load(f)
+        transformed = transform.apply(records)
+        self._normalize(transformed)
 
-        tokenizer_path = raw_config.pop("tokenizer_path", None) or str(root)
-        self.config = PipelineConfig.from_dict(raw_config)
-        tokenizer = AutoTokenizer.from_pretrained(tokenizer_path)
-        mask_builder = MaskBuilderFactory.create("sectioned")
-        position_strategy = PositionIdStrategyFactory.create(
-            self.config.output.position_ids_mode
-        )
+    @property
+    def keys(self) -> List[str]:
+        if self._processor is not None:
+            if self._keys_cache is None and self._num_records > 0:
+                sample = self._processor(self._source.load()[0])
+                self._keys_cache = list(sample.keys())
+            return self._keys_cache or []
+        return list(self._data.keys())
 
-        raw: Dict[str, List[Tensor]] = {}
-        doc_sequences: List[List[int]] = []
+    def fetch_record(self, index: int, keys: Union[str, List[str]]):
+        if self._processor is not None:
+            if not 0 <= index < self._num_records:
+                raise ValueError(
+                    f"Record index out of bounds: {index}, "
+                    f"num_records={self._num_records}"
+                )
+            record = self._source.load()[index]
+            data = self._processor(record)
+            if isinstance(keys, str):
+                return data[keys]
+            return {k: data[k] for k in keys}
+        return _record_fetch(self, index, keys)
 
-        def _process_item(item: dict) -> None:
-            nonlocal raw, doc_sequences
-            result = mask_builder.build(item, self.config, tokenizer)
-            if result is None:
-                return
-            result.pop("domain", None)
-            primary_ids = self._primary_ids(result)
-            if not primary_ids:
-                return
-            doc_sequences.append(primary_ids)
-            for key, ids in result.items():
-                if key not in raw:
-                    raw[key] = []
-                if ids and isinstance(ids[0], list):
-                    # GRPO multi-response: List[List[int]] → List[Tensor]
-                    raw[key].append(
-                        [torch.tensor(sub, dtype=self._infer_dtype(sub)) for sub in ids]
-                    )
-                else:
-                    raw[key].append(torch.tensor(ids, dtype=self._infer_dtype(ids)))
+    def fetch(self, begin: int, end: int, keys: Union[str, List[str]]):
+        if self._processor is not None:
+            raise RuntimeError(
+                "JsonlStore in lazy (processor) mode does not support "
+                "stream fetch(); use fetch_record() instead."
+            )
+        return _stream_fetch(self, begin, end, keys)
 
-        for jsonl_path in sorted(root.glob("*.jsonl")):
-            with open(jsonl_path, "r", encoding="utf-8") as f:
-                for line in f:
-                    line = line.strip()
-                    if not line:
-                        continue
-                    try:
-                        item = json.loads(line)
-                    except json.JSONDecodeError:
-                        logger.warning(
-                            "Failed to parse JSON line in %s, skipping", jsonl_path
-                        )
-                        continue
-                    _process_item(item)
-
-        for json_path in sorted(root.glob("*.json")):
-            if json_path.name == self.CONFIG_NAME:
-                continue
-            with open(json_path, "r", encoding="utf-8") as f:
-                try:
-                    data = json.load(f)
-                except json.JSONDecodeError:
-                    logger.warning("Failed to parse JSON file %s, skipping", json_path)
-                    continue
-            if isinstance(data, list):
-                for item in data:
-                    _process_item(item)
-            elif isinstance(data, dict):
-                _process_item(data)
-
-        pos_ids = position_strategy.generate(doc_sequences)
-        if pos_ids:
-            raw["position_ids"] = [torch.tensor(pos_ids, dtype=torch.int32)]
-
-        self._normalize(raw)
-
-    @staticmethod
-    def _primary_ids(result: dict) -> List[int]:
-        """Return the first flat integer list in *result* as the primary id sequence."""
-        for val in result.values():
-            if isinstance(val, list) and val and isinstance(val[0], int):
-                return val
-        return []
-
-    @staticmethod
-    def _infer_dtype(ids: List) -> torch.dtype:
-        """Infer tensor dtype from the first element of a token/value list."""
-        if ids and isinstance(ids[0], float):
-            return torch.float32
-        return torch.int32
+    def __getitem__(self, index: int) -> Dict[str, Tensor]:
+        if self._processor is not None:
+            return self.fetch_record(index, self._record_keys())
+        return super().__getitem__(index)

astrai/extension/__init__.py

@@ -4,26 +4,52 @@ Public API:
     - ``attn_decode`` — single-query decode attention
     - ``attn_prefill`` — multi-query prefill attention
     - ``attn_paged_decode`` — paged decode attention (direct page-table access)
+    - ``AttentionBackend`` — ABC for attention computation strategies
+    - ``TorchNativeBackend`` — default SDPA backend with KV cache I/O
+    - ``CudaBackend`` — CUDA kernel backend with paged decode + prefill
 
-Interface (shared by all wrappers):
-    causal_offset: -1 = non-causal; >=0 = absolute position of first Q token
-    mask:       2D [batch, kv_len] or 3D [batch, q_len, kv_len] (bool, True = keep)
-    scale:      0.0 = auto (1/sqrt(head_dim)); >0 = explicit
-    layout:     "bhld" (default) or "blhd"
+Layout convention: all q/k/v are ``[batch, seq_len, n_heads, head_dim]``
+(blhd). Scale is always ``1/sqrt(head_dim)``.
 
-Causal and mask can coexist — both are applied simultaneously.
-
-Each wrapper dispatches to its compiled CUDA kernel (``astrai.extension.attn_*``)
-when available, otherwise falls back to ``torch.nn.functional.scaled_dot_product_attention``.
+Each wrapper calls its compiled CUDA kernel directly. Fallback to torch
+SDPA is handled by the attention backend, not the wrapper functions.
 """
 
+from astrai.extension.backend import (
+    ATTN_BACKEND,
+    AttentionBackend,
+    AttentionBackendFactory,
+    CudaBackend,
+    FlashAttnBackend,
+    TorchNativeBackend,
+    apply_rotary_emb,
+    attention,
+    attn_backend,
+    get_backend,
+)
 from astrai.extension.loader import KERNEL_NAMES, is_available
-from astrai.extension.ops import attn_decode, attn_paged_decode, attn_prefill
+from astrai.extension.ops import (
+    TensorLayout,
+    attn_decode,
+    attn_paged_decode,
+    attn_prefill,
+)
 
 __all__ = [
+    "ATTN_BACKEND",
+    "AttentionBackend",
+    "AttentionBackendFactory",
+    "CudaBackend",
+    "TorchNativeBackend",
+    "FlashAttnBackend",
+    "TensorLayout",
+    "attention",
+    "attn_backend",
+    "get_backend",
     "attn_decode",
     "attn_paged_decode",
     "attn_prefill",
     "is_available",
     "KERNEL_NAMES",
+    "apply_rotary_emb",
 ]

astrai/extension/backend/__init__.py

@@ -0,0 +1,27 @@
+"""Backend selection, fallbacks, and execution policies."""
+
+from astrai.extension.backend.attention import (
+    ATTN_BACKEND,
+    AttentionBackend,
+    AttentionBackendFactory,
+    CudaBackend,
+    FlashAttnBackend,
+    TorchNativeBackend,
+    attention,
+    attn_backend,
+    get_backend,
+)
+from astrai.extension.backend.rotary import apply_rotary_emb
+
+__all__ = [
+    "ATTN_BACKEND",
+    "AttentionBackend",
+    "AttentionBackendFactory",
+    "CudaBackend",
+    "FlashAttnBackend",
+    "TorchNativeBackend",
+    "apply_rotary_emb",
+    "attention",
+    "attn_backend",
+    "get_backend",
+]

astrai/extension/backend/attention.py

@@ -0,0 +1,819 @@
+"""Attention backend abstraction with context-manager switching.
+
+The backend encapsulates KV cache I/O and attention computation. The
+attention module (GQA/MLA) keeps projections, rotary, QK-norm, gating,
+and output projection; the backend handles everything from "write K/V
+to cache" through "SDPA output".
+
+Usage — mirroring ``torch.nn.attention.sdpa_kernel``:
+
+    from astrai.extension import attn_backend, ATTN_BACKEND
+
+    with attn_backend(ATTN_BACKEND.TORCH_NATIVE):
+        engine.generate("hello")
+
+    # or with an instance:
+    with attn_backend(TorchNativeBackend()):
+        ...
+
+    # or the shorthand (instance is itself a context manager):
+    with TorchNativeBackend():
+        ...
+
+Thread-safe via ``contextvars`` — each scheduler thread gets its own
+active backend. Backend resolution follows a strict precedence:
+
+1. explicit ``attn_backend(...)`` context (wins over everything),
+2. the process-wide ``ASTR_BACKEND`` environment override,
+3. an implicit default picked from the available backends
+   (cuda > flash > torch).
+
+Capability is polymorphic: every backend declares ``available()``
+(machine-level) and ``supports_call(...)`` (per-call), so adding a new
+backend requires no changes to the resolution logic. Training calls
+(``fwd=None``, no KV cache) resolve through the same priority list: the
+CUDA cache kernels cannot run without a cache, so they fall back to
+flash (when it can handle the call — mask-free/causal only) and finally
+to the reference ``TorchNativeBackend``.
+
+Layout convention: all q/k/v are ``[batch, seq_len, n_heads, head_dim]``
+(blhd). The backend returns ``[batch, seq_len, n_heads * head_dim]``.
+"""
+
+import contextvars
+import enum
+import functools
+import logging
+import os
+import threading
+from abc import ABC, abstractmethod
+from contextlib import contextmanager
+from typing import TYPE_CHECKING, Dict, Optional, Tuple, Union
+
+import torch
+import torch.nn.functional as F
+from torch import Tensor
+
+from astrai.extension.loader import is_available
+from astrai.extension.ops.attention import (
+    attn_paged_decode,
+    attn_paged_prefill,
+)
+from astrai.factory import BaseFactory
+
+try:
+    import flash_attn as _flash_attn
+except Exception:
+    _flash_attn = None
+
+if TYPE_CHECKING:
+    from astrai.inference.cache import KVCache
+
+logger = logging.getLogger(__name__)
+
+
+_default_backend_lock = threading.Lock()
+_env_backend_name: Optional[str] = None
+_env_backend: Optional["AttentionBackend"] = None
+_current_backend: contextvars.ContextVar[Optional["AttentionBackend"]] = (
+    contextvars.ContextVar("attn_backend", default=None)
+)
+
+# Backends are stateless — one canonical instance per class, created lazily
+# and reused everywhere (resolution, fallback, context managers).
+_singletons: Dict[type, "AttentionBackend"] = {}
+
+
+@functools.lru_cache(maxsize=1)
+def flash_attn_available() -> bool:
+    if not torch.cuda.is_available():
+        return False
+    fa = _flash_attn
+    if fa is None:
+        return False
+
+    try:
+        major = int(fa.__version__.split(".")[0])
+        cc = torch.cuda.get_device_capability()
+        cc_num = cc[0] * 10 + cc[1]
+    except Exception:
+        major, cc_num = 0, 0
+    if (major >= 3 and cc_num < 90) or (major < 3 and 0 < cc_num < 70):
+        return False
+
+    try:
+        if not hasattr(fa, "flash_attn_func"):
+            return False
+        x = torch.zeros(1, 1, 1, 64, device="cuda", dtype=torch.bfloat16)
+        out = fa.flash_attn_func(x, x, x, causal=True)
+        return bool(torch.isfinite(out).all().item())
+    except Exception:
+        return False
+
+
+class ATTN_BACKEND(enum.Enum):
+    """Backend selector enum, mirroring ``torch.nn.attention.SDPBackend``."""
+
+    TORCH_NATIVE = "torch_native"
+    CUDA = "cuda"
+    FLASH = "flash"
+
+
+def _instance(backend_cls: type) -> "AttentionBackend":
+    """Return the canonical singleton instance for a backend class.
+
+    Backends hold no per-instance state, so a single cached instance is
+    safe and avoids per-call allocation on the attention hot path.
+    """
+    backend = _singletons.get(backend_cls)
+    if backend is None:
+        backend = backend_cls()
+        _singletons[backend_cls] = backend
+    return backend
+
+
+@functools.lru_cache(maxsize=1)
+def _priority_backends() -> Tuple["AttentionBackend", ...]:
+    """Available backends in priority order: cuda -> flash -> torch.
+
+    Computed once (machine availability cannot change at runtime) and
+    cached forever; the tuple always ends with ``TorchNativeBackend``,
+    which is unconditionally available.
+    """
+    return tuple(
+        _instance(cls)
+        for cls in (CudaBackend, FlashAttnBackend, TorchNativeBackend)
+        if cls.available()
+    )
+
+
+def _resolve_default_backend() -> "AttentionBackend":
+    """Pick the highest-priority available backend (cuda -> flash -> torch).
+
+    Resolved lazily on first use and cached via ``_priority_backends``.
+    Per-call capability fallback happens in ``attention()``, so the
+    default is safe for training and fp32 models.
+    """
+    return _priority_backends()[0]
+
+
+def _environment_backend() -> Optional["AttentionBackend"]:
+    """Resolve the process-wide ``ASTR_BACKEND`` override, if configured."""
+    global _env_backend, _env_backend_name
+    name = os.environ.get("ASTR_BACKEND", "").strip().lower()
+    if not name:
+        return None
+    if name != _env_backend_name:
+        with _default_backend_lock:
+            if name != _env_backend_name:
+                try:
+                    _env_backend = _resolve_backend(name)
+                except (ValueError, RuntimeError):
+                    _env_backend = None
+                    logger.warning(
+                        "ASTR_BACKEND=%r is not a registered attention backend; "
+                        "falling back to default resolution",
+                        name,
+                    )
+                _env_backend_name = name
+    return _env_backend
+
+
+def _resolve_backend(
+    backend: Optional[Union[str, ATTN_BACKEND, "AttentionBackend", type]] = None,
+) -> "AttentionBackend":
+    """Resolve a backend configuration to its canonical instance.
+
+    Accepts a registered name, ``ATTN_BACKEND`` enum value, backend class,
+    or instance.  Names/classes resolve to the shared singleton; a caller
+    may still pass its own instance to opt out of sharing.
+    """
+    if backend is not None:
+        if isinstance(backend, ATTN_BACKEND):
+            return _instance(AttentionBackendFactory.get_component_class(backend.value))
+        if isinstance(backend, str):
+            return _instance(AttentionBackendFactory.get_component_class(backend))
+        if isinstance(backend, type) and issubclass(backend, AttentionBackend):
+            return _instance(backend)
+        if isinstance(backend, AttentionBackend):
+            return backend
+        raise TypeError(
+            f"expected a registered name, ATTN_BACKEND, AttentionBackend type, "
+            f"or instance, got {type(backend).__name__}"
+        )
+    return _resolve_default_backend()
+
+
+def get_backend(
+    use_default: bool = True,
+) -> Optional["AttentionBackend"]:
+    """Resolve the active backend: explicit context > env > default.
+
+    An ``attn_backend(...)`` context is the caller's explicit choice and
+    always wins.  ``ASTR_BACKEND`` is a process-wide override consulted
+    only when no context is set.  Pass ``use_default=False`` at request
+    submission to retain only an environment override or the caller's
+    :func:`attn_backend` value.
+    """
+    context_backend = _current_backend.get()
+    if context_backend is not None:
+        return context_backend
+    env_backend = _environment_backend()
+    if env_backend is not None:
+        return env_backend
+    return _resolve_default_backend() if use_default else None
+
+
+@contextmanager
+def attn_backend(backend: Union[str, ATTN_BACKEND, "AttentionBackend", type]):
+    """Context manager to select an attention backend.
+
+    Mirrors ``torch.nn.attention.sdpa_kernel``. Accepts an
+    registered name, ``ATTN_BACKEND`` enum value, backend class, or instance.
+
+    Examples::
+
+        with attn_backend(ATTN_BACKEND.TORCH_NATIVE):
+            ...
+        with attn_backend(TorchNativeBackend):
+            ...
+        with attn_backend(TorchNativeBackend()):
+            ...
+    """
+    instance = _resolve_backend(backend)
+    token = _current_backend.set(instance)
+    try:
+        yield instance
+    finally:
+        _current_backend.reset(token)
+
+
+def repeat_kv(x: Tensor, n_rep: int) -> Tensor:
+    """Expand KV heads to match Q heads for GQA."""
+    if n_rep == 1:
+        return x
+    n_heads, head_dim = x.shape[-2:]
+    return (
+        x.unsqueeze(-2)
+        .expand(*x.shape[:-2], n_heads, n_rep, head_dim)
+        .reshape(*x.shape[:-2], n_heads * n_rep, head_dim)
+    )
+
+
+def attention(
+    q: Tensor,
+    k: Tensor,
+    v: Tensor,
+    kv_cache: Optional["KVCache"] = None,
+    layer_id: int = 0,
+    attn_mask: Optional[Tensor] = None,
+    is_causal: bool = False,
+    fwd: Optional[str] = None,
+    backend: Optional[Union[str, ATTN_BACKEND, "AttentionBackend", type]] = None,
+) -> Tensor:
+    """Functional attention entry point — mirrors ``F.scaled_dot_product_attention``.
+
+    Delegates to the active backend.  ``backend`` (optional) is an explicit
+    escape hatch; when omitted the backend is resolved as
+    explicit context > ``ASTR_BACKEND`` env > default (cuda > flash > torch).
+    Handles KV cache I/O, GQA head expansion, and causal masking so the
+    caller only needs to provide projected q/k/v.
+
+    Training calls (``fwd=None``, ``kv_cache=None``) resolve through the
+    same capability chain — the CUDA cache kernels cannot run without a
+    cache, so they fall back to flash (mask-free/causal calls only) and
+    finally to torch SDPA.  An explicitly-selected backend that cannot
+    handle the call raises — an implicit one falls back down the priority
+    list to the first capable backend.
+
+    Args:
+        q: [batch, q_len, n_heads, head_dim] (blhd)
+        k: [batch, q_len, n_kv_heads, head_dim] (blhd)
+        v: [batch, q_len, n_kv_heads, head_dim] (blhd)
+        kv_cache: cache dataclass, or None for training (no cache).
+        layer_id: transformer layer index for buffer access.
+        attn_mask: pre-built attention mask (SDPA-compatible).
+        is_causal: whether to apply causal masking.
+        fwd: "prefill" / "decode" for inference, None for training.
+        backend: optional explicit backend (name, enum, class, or instance).
+
+    Returns:
+        [batch, q_len, n_heads * head_dim]
+    """
+    if backend is not None:
+        selected = _resolve_backend(backend)
+        explicit = True
+    else:
+        context_backend = _current_backend.get()
+        explicit = context_backend is not None
+        # Resolve through the same chain as inference: explicit context >
+        # ASTR_BACKEND env > default.  Training calls (fwd=None, no cache)
+        # land on the CUDA backend and fall back by capability below —
+        # flash when it can handle the call, else torch SDPA.
+        selected = get_backend()
+        assert selected is not None
+
+    if not selected.supports_call(q, kv_cache, attn_mask, is_causal, fwd):
+        if explicit:
+            raise RuntimeError(
+                f"Explicitly-set backend {type(selected).__name__} cannot "
+                f"handle this attention call (shape={q.shape}, "
+                f"dtype={q.dtype}, kv_cache={'none' if kv_cache is None else 'present'}, "
+                f"attn_mask={'none' if attn_mask is None else 'present'}). "
+                f"Remove the attn_backend() context or switch to a compatible backend."
+            )
+        selected = next(
+            (
+                candidate
+                for candidate in _priority_backends()
+                if candidate.supports_call(q, kv_cache, attn_mask, is_causal, fwd)
+            ),
+            _instance(TorchNativeBackend),
+        )
+    return selected.forward(q, k, v, kv_cache, layer_id, attn_mask, is_causal, fwd)
+
+
+class AttentionBackend(ABC):
+    """Abstract base for attention computation strategies.
+
+    Subclasses implement ``fwd_decode`` (q_len == 1, with cache) and
+    ``fwd_prefill`` (q_len > 1, with or without cache). The public
+    ``forward`` method dispatches based on q_len.
+
+    Capability contract — every backend declares:
+
+    * ``available()`` — machine-level: can this backend exist here
+      (kernel ``.so`` loaded, flash-attn present, GPU available)?
+      Used once to build the default priority list.
+    * ``supports_call(q, kv_cache, attn_mask, is_causal, fwd)`` — can this
+      backend run this *specific* call (shape/dtype/cache/mask)?  Used by
+      ``attention()`` for the per-call fallback.  Resolution logic never
+      checks concrete backend types, so adding a backend requires no
+      changes outside its own class.
+
+    Three equivalent ways to activate a backend::
+
+        with attn_backend(ATTN_BACKEND.TORCH_NATIVE):  # enum
+            ...
+        with attn_backend(TorchNativeBackend):          # class
+            ...
+        with TorchNativeBackend():                       # instance
+            ...
+    """
+
+    def __enter__(self) -> "AttentionBackend":
+        self._token = _current_backend.set(self)
+        return self
+
+    def __exit__(self, *exc) -> None:
+        _current_backend.reset(self._token)
+
+    @classmethod
+    @abstractmethod
+    def available(cls) -> bool:
+        """Return True if this backend can run on the current machine.
+
+        Checks static availability only (compiled kernels, optional
+        packages, GPU presence) — not call-specific constraints.
+        """
+
+    @abstractmethod
+    def supports_call(
+        self,
+        q: Tensor,
+        kv_cache: Optional["KVCache"],
+        attn_mask: Optional[Tensor],
+        is_causal: bool,
+        fwd: Optional[str],
+    ) -> bool:
+        """Return True if this backend can run this specific attention call.
+
+        Called on the canonical singleton instance (or a caller-provided
+        one); must be side-effect free.
+        """
+
+    def forward(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+        fwd: Optional[str] = None,
+    ) -> Tensor:
+        """Dispatch to decode or extend based on q_len.
+
+        Args:
+            q: [batch, q_len, n_heads, head_dim]
+            k: [batch, q_len, n_kv_heads, head_dim]
+            v: [batch, q_len, n_kv_heads, head_dim]
+            kv_cache: cache dataclass, or None for training (no cache).
+            layer_id: transformer layer index for buffer access.
+            attn_mask: pre-built attention mask compatible with SDPA.
+            is_causal: whether to apply causal masking.
+
+        Returns:
+            [batch, q_len, n_heads * head_dim]
+        """
+        if fwd == "decode":
+            return self.fwd_decode(q, k, v, kv_cache, layer_id, attn_mask, is_causal)
+        if fwd == "prefill" or fwd is None:
+            return self.fwd_prefill(q, k, v, kv_cache, layer_id, attn_mask, is_causal)
+        raise ValueError(f"unsupported attention forward mode: {fwd}")
+
+    @abstractmethod
+    def fwd_decode(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        """Single-token decode with KV cache."""
+
+    @abstractmethod
+    def fwd_prefill(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        """Multi-token prefill or training forward."""
+
+    @staticmethod
+    def supports_graph() -> bool:
+        """Return True if this backend supports CUDA-graph capture.
+
+        Override in subclasses that can run under ``torch.cuda.graph``.
+
+        Called on the *active* backend instance (or its class) — a cheap
+        boolean check with no side-effects.
+        """
+        return False
+
+
+class AttentionBackendFactory(BaseFactory[AttentionBackend]):
+    """Factory for registered attention backends."""
+
+
+@AttentionBackendFactory.register(ATTN_BACKEND.TORCH_NATIVE.value)
+class TorchNativeBackend(AttentionBackend):
+    """Reference backend using torch SDPA with indirect KV cache indexing.
+
+    Writes new K/V into the cache buffers, gathers the full sequence K/V
+    via ``req_to_token`` indirect indexing, then calls
+    ``F.scaled_dot_product_attention``.
+
+    For training (``kv_cache is None``), skips cache I/O entirely and
+    runs SDPA directly on the projected q/k/v.
+    """
+
+    @classmethod
+    def available(cls) -> bool:
+        return True
+
+    def supports_call(
+        self,
+        q: Tensor,
+        kv_cache: Optional["KVCache"],
+        attn_mask: Optional[Tensor],
+        is_causal: bool,
+        fwd: Optional[str],
+    ) -> bool:
+        return True
+
+    def fwd_decode(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        return self._forward(q, k, v, kv_cache, layer_id, attn_mask, is_causal)
+
+    def fwd_prefill(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        return self._forward(q, k, v, kv_cache, layer_id, attn_mask, is_causal)
+
+    def _forward(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        if q.ndim == 4:
+            n_rep = q.size(2) // k.size(2)
+            if n_rep > 1:
+                k = repeat_kv(k, n_rep)
+                v = repeat_kv(v, n_rep)
+            return (
+                F.scaled_dot_product_attention(
+                    q.permute(0, 2, 1, 3),
+                    k.permute(0, 2, 1, 3),
+                    v.permute(0, 2, 1, 3),
+                    attn_mask,
+                    is_causal=is_causal,
+                )
+                .permute(0, 2, 1, 3)
+                .contiguous()
+            )
+
+        if kv_cache is None or kv_cache.qo_indptr is None:
+            raise ValueError("packed attention requires KV cache metadata")
+        kv_cache.k_buffer[layer_id, kv_cache.out_cache_loc] = k
+        kv_cache.v_buffer[layer_id, kv_cache.out_cache_loc] = v
+        outputs = []
+        n_rep = q.size(1) // k.size(1)
+        for i in range(kv_cache.req_pool_indices.numel()):
+            q_start = int(kv_cache.qo_indptr[i])
+            q_end = int(kv_cache.qo_indptr[i + 1])
+            indices = kv_cache.req_to_token[
+                kv_cache.req_pool_indices[i], : kv_cache.seq_lens[i]
+            ]
+            k_i = kv_cache.k_buffer[layer_id, indices]
+            v_i = kv_cache.v_buffer[layer_id, indices]
+            if n_rep > 1:
+                k_i = repeat_kv(k_i, n_rep)
+                v_i = repeat_kv(v_i, n_rep)
+            q_len = q_end - q_start
+            kv_len = k_i.size(0)
+            q_pos = torch.arange(kv_len - q_len, kv_len, device=q.device)
+            causal_mask = q_pos[:, None] >= torch.arange(kv_len, device=q.device)
+            out = F.scaled_dot_product_attention(
+                q[q_start:q_end].transpose(0, 1).unsqueeze(0),
+                k_i.transpose(0, 1).unsqueeze(0),
+                v_i.transpose(0, 1).unsqueeze(0),
+                attn_mask=causal_mask,
+            )
+            outputs.append(out.squeeze(0).transpose(0, 1))
+        return torch.cat(outputs)
+
+
+@AttentionBackendFactory.register(ATTN_BACKEND.CUDA.value)
+class CudaBackend(AttentionBackend):
+    """CUDA kernel backend with direct KV cache access.
+
+    Decode path: writes K/V to the flat pool, then calls
+    ``attn_paged_decode`` with req_to_token + kv_indptr.
+
+    Prefill path: writes K/V to the flat pool, then calls
+    ``attn_paged_prefill`` with ragged-batch support via qo_indptr +
+    kv_indptr.
+
+    ``kv_cache is None`` (training) raises — the per-call fallback to
+    torch SDPA for training / fp32 / unsupported head_dim happens in the
+    ``attention()`` entry point.
+
+    Raises ``RuntimeError`` if the required kernel is not available.
+    """
+
+    # Head dims supported by the CUDA kernels (single source of truth).
+    HEAD_DIMS = (32, 64, 128, 256)
+
+    @classmethod
+    def available(cls) -> bool:
+        return (
+            torch.cuda.is_available()
+            and is_available("attn_paged_decode")
+            and is_available("attn_paged_prefill")
+        )
+
+    def supports_call(
+        self,
+        q: Tensor,
+        kv_cache: Optional["KVCache"],
+        attn_mask: Optional[Tensor],
+        is_causal: bool,
+        fwd: Optional[str],
+    ) -> bool:
+        # The CUDA kernels are bf16-only, support head_dim in
+        # HEAD_DIMS, and need a KV cache (decode/prefill); everything
+        # else falls back down the priority list to torch.
+        return (
+            fwd in ("prefill", "decode")
+            and kv_cache is not None
+            and q.ndim == 3
+            and q.dtype == torch.bfloat16
+            and q.size(-1) in self.HEAD_DIMS
+            and is_available(f"attn_paged_{fwd}")
+        )
+
+    @staticmethod
+    def supports_graph() -> bool:
+        return True
+
+    def fwd_decode(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        if kv_cache is None:
+            raise RuntimeError("CudaBackend does not support training (kv_cache=None)")
+
+        kv_indptr = kv_cache.kv_indptr
+
+        out = attn_paged_decode(
+            q,
+            kv_cache.k_buffer[layer_id],
+            kv_cache.v_buffer[layer_id],
+            kv_cache.req_to_token,
+            kv_cache.req_pool_indices,
+            kv_indptr,
+            new_k=k,
+            new_v=v,
+            is_causal=True,
+            o_part_buf=kv_cache.decode_o_part,
+            ml_part_buf=kv_cache.decode_ml_part,
+            out_buf=kv_cache.decode_out,
+        )
+        return out
+
+    def fwd_prefill(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        if kv_cache is None:
+            raise RuntimeError("CudaBackend does not support training (kv_cache=None)")
+
+        loc = kv_cache.out_cache_loc
+        kv_cache.k_buffer[layer_id, loc] = k
+        kv_cache.v_buffer[layer_id, loc] = v
+
+        out = attn_paged_prefill(
+            q,
+            kv_cache.k_buffer[layer_id],
+            kv_cache.v_buffer[layer_id],
+            kv_cache.req_to_token,
+            kv_cache.req_pool_indices,
+            kv_cache.kv_indptr,
+            kv_cache.qo_indptr,
+            kv_cache.q_tile_to_batch,
+            kv_cache.q_tile_to_index,
+            attn_mask,
+            is_causal=is_causal,
+        )
+        return out
+
+
+@AttentionBackendFactory.register(ATTN_BACKEND.FLASH.value)
+class FlashAttnBackend(AttentionBackend):
+    """FlashAttention backend via the optional ``flash-attn`` package.
+
+    Decode (q_len=1, contiguous cache): writes K/V to the pool, gathers
+    flat K/V via the ``req_to_token`` page table, and calls
+    ``flash_attn_varlen_func`` over the ragged batch
+    (``qo_indptr``/``kv_indptr``).
+
+    Prefill: packed 3-D calls share the ``flash_attn_varlen_func`` path;
+    dense 4-D calls go through ``flash_attn_func`` (mask-free only).
+    """
+
+    @classmethod
+    def available(cls) -> bool:
+        return flash_attn_available()
+
+    def supports_call(
+        self,
+        q: Tensor,
+        kv_cache: Optional["KVCache"],
+        attn_mask: Optional[Tensor],
+        is_causal: bool,
+        fwd: Optional[str],
+    ) -> bool:
+        if not self.available():
+            return False
+        if q.dtype not in (torch.float16, torch.bfloat16):
+            return False
+        if fwd is not None:
+            return q.ndim == 3 and hasattr(_flash_attn, "flash_attn_varlen_func")
+        # Dense (training) path: flash_attn_func cannot apply a custom
+        # mask, so only mask-free calls are supported — ``is_causal`` is
+        # a flag, not a mask.  Masked training (SFT/DPO/GRPO) must fall
+        # back to TorchNativeBackend instead of silently ignoring the mask.
+        return attn_mask is None
+
+    def fwd_decode(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        return self._forward_packed(q, k, v, kv_cache, layer_id)
+
+    def fwd_prefill(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: Optional["KVCache"],
+        layer_id: int,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        if q.ndim == 3:
+            return self._forward_packed(q, k, v, kv_cache, layer_id)
+        return self._forward_dense(q, k, v, attn_mask, is_causal)
+
+    def _forward_dense(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        attn_mask: Optional[Tensor] = None,
+        is_causal: bool = False,
+    ) -> Tensor:
+        n_rep = q.size(2) // k.size(2)
+        if n_rep > 1:
+            k = repeat_kv(k, n_rep)
+            v = repeat_kv(v, n_rep)
+
+        if attn_mask is not None:
+            raise ValueError(
+                "FlashAttnBackend cannot handle a custom attention mask; "
+                "use a causal mask or select TorchNativeBackend."
+            )
+        fa = _flash_attn
+        if fa is None:
+            raise RuntimeError(
+                "FlashAttnBackend requires the optional 'flash-attn' package. "
+                "Install with `pip install flash-attn`."
+            )
+        out = fa.flash_attn_func(
+            q.contiguous(),
+            k.contiguous(),
+            v.contiguous(),
+            causal=is_causal,
+        )
+        return out.contiguous()
+
+    def _forward_packed(
+        self,
+        q: Tensor,
+        k: Tensor,
+        v: Tensor,
+        kv_cache: "KVCache",
+        layer_id: int,
+    ) -> Tensor:
+        fa = _flash_attn
+        if fa is None or not hasattr(fa, "flash_attn_varlen_func"):
+            raise RuntimeError("packed inference requires flash_attn_varlen_func")
+        kv_cache.k_buffer[layer_id, kv_cache.out_cache_loc] = k
+        kv_cache.v_buffer[layer_id, kv_cache.out_cache_loc] = v
+        page_table = kv_cache.req_to_token[
+            kv_cache.req_pool_indices, : kv_cache.max_len
+        ]
+        positions = torch.arange(kv_cache.max_len, device=q.device)
+        indices = page_table[positions.unsqueeze(0) < kv_cache.seq_lens.unsqueeze(1)]
+        k_flat = kv_cache.k_buffer[layer_id, indices].contiguous()
+        v_flat = kv_cache.v_buffer[layer_id, indices].contiguous()
+        out = fa.flash_attn_varlen_func(
+            q.contiguous(),
+            k_flat,
+            v_flat,
+            kv_cache.qo_indptr,
+            kv_cache.kv_indptr,
+            int((kv_cache.qo_indptr[1:] - kv_cache.qo_indptr[:-1]).max()),
+            int(kv_cache.seq_lens.max()),
+            dropout_p=0.0,
+            causal=True,
+        )
+        return out

astrai/extension/backend/rotary.py

@@ -0,0 +1,53 @@
+"""Rotary embedding with auto-dispatch to CUDA kernel.
+
+Single entry point ``apply_rotary_emb(x, freqs_cis)`` — uses the fused
+CUDA kernel when available, falls back to torch complex multiply otherwise.
+
+Layout: x is [batch, seq_len, n_heads, head_dim] (bf16).
+freqs_cis is [batch, seq_len, dim/2, 2] (f32) — [cos, sin] pairs.
+"""
+
+import torch
+from torch import Tensor
+
+from astrai.extension.loader import is_available
+from astrai.extension.ops.rotary import rotary_emb as _cuda_rotary
+
+_cache = {"available": None}
+
+
+def _cuda_available() -> bool:
+    if _cache["available"] is None:
+        _cache["available"] = is_available("rotary_emb")
+    return _cache["available"]
+
+
+def _torch_apply(x: Tensor, freqs_cis: Tensor) -> Tensor:
+    cos, sin = freqs_cis[..., 0], freqs_cis[..., 1]
+    dtype = x.dtype
+    x_ = x.float().reshape(*x.shape[:-1], -1, 2)
+    x_complex = torch.view_as_complex(x_)
+    freqs_cis_complex = torch.complex(cos, sin).unsqueeze(-2)
+    x_rotated = x_complex * freqs_cis_complex
+    x_out = torch.view_as_real(x_rotated).flatten(-2)
+    return x_out.to(dtype)
+
+
+def apply_rotary_emb(x: Tensor, freqs_cis: Tensor) -> Tensor:
+    """Apply rotary embedding to x.
+
+    Args:
+        x: [batch, seq_len, n_heads, head_dim] (bf16)
+        freqs_cis: [batch, seq_len, dim/2, 2] (f32) — [cos, sin] pairs
+
+    Returns:
+        [batch, seq_len, n_heads, head_dim] (bf16)
+    """
+    if (
+        _cuda_available()
+        and not torch.is_grad_enabled()
+        and x.is_cuda
+        and x.dtype == torch.bfloat16
+    ):
+        return _cuda_rotary(x, freqs_cis)
+    return _torch_apply(x, freqs_cis)

astrai/extension/fp8.py

@@ -0,0 +1,450 @@
+"""FP8 training: scaling recipes, per-tensor state, and aten::linear dispatch.
+
+Layered (see ``ops/fp8.py`` for the CUDA interface adapter):
+1. ``ops.fp8`` — the only module touching the pybind.
+2. This module (strategy layer): scaling *recipes* (TE-style delayed scaling
+   or dynamic current-amax scaling), per-tensor scales + amax history, and the
+   ``fp8_autocast`` context manager (like ``torch.autocast``).
+3. aten::linear integration: registers the CUDA + AutogradCUDA impls.
+
+Usage::
+
+    from astrai.extension.fp8 import fp8_autocast
+    with fp8_autocast(enabled=True, fp8_format="hybrid"):
+        logits = model(input_ids)
+    loss.backward()  # fp8 backward runs anywhere; fwd captured state on the node
+
+Format defaults follow the ecosystem consensus: E4M3 forward / E5M2 backward
+("hybrid"); every operand's scale is a quantization step derived from its amax
+history by the active recipe.
+
+The context mirrors ``torch.autocast`` (``autocast_mode.py``): the active
+``(enabled, recipe, fp8_format)`` triple is thread-local (a ``contextvars``
+``ContextVar``, absent outside any region), and the manager is class-based and
+reentrant with nested ``enabled=False`` disabling dispatch inside it. The module
+targets *training*: every step quantizes x/w/g fresh (no weight-cast cache — the
+optimizer bumps the weight version each step, so a torch-style cached_cast would
+miss anyway), and the per-operand scales come from the delayed/dynamic recipe.
+"""
+
+import functools
+from contextvars import ContextVar, Token
+from dataclasses import dataclass
+from enum import Enum
+from typing import Dict, List, NamedTuple, Optional
+
+import torch
+from torch.library import Library
+
+from astrai.extension.ops.fp8 import mm_fp8, quantize, quantize_dual
+
+# Max representable value per FP8 format (E4M3: 448, E5M2: 57344).
+FP8_MAX = {"e4m3": 448.0, "e5m2": 57344.0}
+
+
+class FP8Format(str, Enum):
+    """Per-direction FP8 format. HYBRID = E4M3 forward / E5M2 backward."""
+
+    E4M3 = "e4m3"
+    E5M2 = "e5m2"
+    HYBRID = "hybrid"
+
+    def fwd(self) -> str:
+        return "e4m3" if self is FP8Format.HYBRID else self.value
+
+    def bwd(self) -> str:
+        return "e5m2" if self is FP8Format.HYBRID else self.value
+
+
+@dataclass
+class FP8Recipe:
+    """Scale-from-amax policy: ``scale = (amax / FP8_MAX[fmt]) / 2^margin``.
+
+    ``dynamic=False`` (default) is TE-style delayed scaling: max over the
+    amax history window (amax from *previous* steps; the window trades
+    responsiveness against stability). ``dynamic=True`` is current-amax
+    scaling (torchao DYNAMIC): measure, then quantize — no history, at an
+    extra pass. ``scale_from_history`` receives the operand's amax tensor
+    (a ring window / the current amax) and returns the quantization step.
+    """
+
+    history_len: int = 16
+    margin: int = 0
+    dynamic: bool = False
+
+    def scale_from_history(self, amax: torch.Tensor, fmt: str) -> torch.Tensor:
+        peak = amax.max()
+        return ((peak / FP8_MAX[fmt]) / (2**self.margin)).clamp_min(1e-12)
+
+
+class _ScaleRing:
+    """One operand's delayed-scaling state: a float32 buffer
+    ``[hist[n] | scale | legacy | amax | done]`` (views). The quantize
+    kernel folds its fused amax into ``hist[idx]`` and publishes the next
+    scale from the window in its own last block (``fold_args`` passes the
+    buffer + recipe constants); ``idx`` advances host-side each use. The
+    ``amax``/``done`` tail slots are kernel scratch (self-cleaning across
+    launches); the legacy slot keeps state-buffer compatibility.
+    """
+
+    __slots__ = ("recipe", "state", "hist", "scale", "idx", "initialized")
+
+    def __init__(self, device: torch.device, recipe: FP8Recipe):
+        self.recipe = recipe
+        n = recipe.history_len
+        self.state = torch.zeros(n + 4, device=device, dtype=torch.float32)
+        self.hist = self.state[:n]
+        self.scale = self.state[n : n + 1]
+        self.idx = 0
+        self.initialized = False
+
+    def advance(self) -> None:
+        """Rotate to the next history slot after metadata update."""
+        self.idx = (self.idx + 1) % self.hist.numel()
+
+    def seed(self, t: torch.Tensor, fmt: str) -> None:
+        amax = t.abs().amax().to(torch.float32).clamp_min(1e-12)
+        self.hist.fill_(amax)
+        self.scale.copy_(self.recipe.scale_from_history(self.hist, fmt))
+        self.initialized = True
+
+    def fold_args(self, fmt: str) -> dict:
+        """Keyword arguments for quantize()'s in-kernel history fold."""
+        return {
+            "ring_state": self.state,
+            "hist_idx": self.idx,
+            "fp8_max": FP8_MAX[fmt],
+            "pow2_margin": float(2**self.recipe.margin),
+        }
+
+
+class FP8TensorMeta(NamedTuple):
+    """Per-weight delayed-scaling rings for ``w``, ``x`` and ``g``.
+
+    Dynamic scaling never allocates a meta; it measures the current amax inline.
+    """
+
+    w: _ScaleRing
+    x: _ScaleRing
+    g: _ScaleRing
+
+
+@dataclass(frozen=True)
+class _ActiveConfig:
+    """The immutable (enabled, recipe, format) triple of one open region."""
+
+    enabled: bool
+    recipe: FP8Recipe
+    fp8_format: FP8Format
+
+
+# Thread-local active configuration (torch's autocast TLS analog): set by
+# fp8_autocast on __enter__, absent outside any region. Autograd engine
+# threads run backwards with their own empty context — fine, since backward
+# only reads state captured on ctx at forward time.
+_active_config: ContextVar[Optional[_ActiveConfig]] = ContextVar(
+    "astrai_fp8_active_config", default=None
+)
+
+
+class FP8State:
+    """Global fp8 training state: per-tensor metas + out-of-region defaults.
+
+    The active ``(enabled, recipe, fp8_format)`` triple is a ``ContextVar``
+    set by ``fp8_autocast`` (see ``_active``/``_current_config``); these plain
+    attributes are the persistent defaults applied outside any region —
+    ``fp8_linear_enable`` writes ``default_enabled``. The metas registry is
+    shared across threads (GIL-protected); fp8 backward runs on autograd
+    engine threads and only touches metas captured on ``ctx`` at forward time.
+    """
+
+    def __init__(self):
+        self.default_enabled = False
+        self.default_recipe: FP8Recipe = FP8Recipe()
+        self.default_format: FP8Format = FP8Format.HYBRID
+        self._metas: Dict[tuple, FP8TensorMeta] = {}
+
+    def get_weight_meta(self, w: torch.Tensor, recipe: FP8Recipe) -> FP8TensorMeta:
+        key = (w.data_ptr(), w.shape, w.dtype)
+        meta = self._metas.get(key)
+        if meta is None:
+            meta = FP8TensorMeta(
+                _ScaleRing(w.device, recipe),
+                _ScaleRing(w.device, recipe),
+                _ScaleRing(w.device, recipe),
+            )
+            self._metas[key] = meta
+        return meta
+
+    def reset(self) -> None:
+        """Restore construction defaults (switch, recipe, format) and drop all
+        per-weight metas — a full state reset for tests / reconfiguration."""
+        self.default_enabled = False
+        self.default_recipe = FP8Recipe()
+        self.default_format = FP8Format.HYBRID
+        self._metas.clear()
+
+
+# Process-wide singleton; per-thread/per-region state lives in _active_config.
+_state = FP8State()
+
+
+def fp8_state() -> FP8State:
+    return _state
+
+
+def _active() -> Optional[_ActiveConfig]:
+    """The active config when fp8 dispatch is on, else ``None`` (fast guard).
+
+    A region config wins (honoring nested ``enabled=False`` regions); with no
+    region open this falls back to the persistent global switch
+    (``fp8_linear_enable``), so that flag still routes aten::linear to fp8.
+    """
+    cfg = _active_config.get()
+    if cfg is not None:
+        return cfg if cfg.enabled else None
+    if _state.default_enabled:
+        return _ActiveConfig(True, _state.default_recipe, _state.default_format)
+    return None
+
+
+def _current_config() -> _ActiveConfig:
+    """Like ``_active()`` but always returns a config (disabled regions and
+    out-of-region direct calls resolve to the global defaults)."""
+    cfg = _active_config.get()
+    if cfg is not None:
+        return cfg
+    return _ActiveConfig(
+        _state.default_enabled, _state.default_recipe, _state.default_format
+    )
+
+
+class fp8_autocast:
+    """Autocast-style context: fp8 linear dispatch on this thread.
+
+    Mirrors ``torch.autocast`` — a class-based, reentrant, nestable context
+    over thread-local state::
+
+        with fp8_autocast(enabled=True, fp8_format="hybrid"):
+            logits = model(input_ids)   # aten::linear -> fp8 path
+        loss.backward()  # fp8 backward; state was captured at forward time
+
+    Nesting follows torch: each ``__enter__`` pushes the new active config, each
+    ``__exit__`` restores the previous one, and a nested ``enabled=False`` region
+    simply disables dispatch inside it. The instance doubles as a decorator.
+    """
+
+    def __init__(
+        self,
+        enabled: bool = True,
+        update_interval: int = 16,
+        recipe: Optional[FP8Recipe] = None,
+        fp8_format: str = "hybrid",
+        margin: int = 0,
+    ):
+        if recipe is None:
+            recipe = FP8Recipe(history_len=update_interval, margin=margin)
+        self._config = _ActiveConfig(bool(enabled), recipe, FP8Format(fp8_format))
+        self._tokens: List[Token] = []
+
+    def __enter__(self) -> "fp8_autocast":
+        self._tokens.append(_active_config.set(self._config))
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb) -> bool:
+        token = self._tokens.pop()
+        _active_config.reset(token)
+        return False
+
+    def __call__(self, func):
+        @functools.wraps(func)
+        def decorate(*args, **kwargs):
+            with self:
+                return func(*args, **kwargs)
+
+        return decorate
+
+
+# ---------------------------------------------------------------------------
+# Strategy-level forward / backward (called from the aten::linear impl)
+# ---------------------------------------------------------------------------
+
+
+def _dynamic_scale(t: torch.Tensor, recipe: FP8Recipe, fmt: str) -> torch.Tensor:
+    amax = t.abs().amax().to(torch.float32).clamp_min(1e-12)
+    return recipe.scale_from_history(amax, fmt)
+
+
+def _is_fp8(dtype: torch.dtype) -> bool:
+    """A pre-quantized weight takes the GEMM directly (no re-quantize)."""
+    return dtype in (torch.float8_e4m3fn, torch.float8_e5m2)
+
+
+def fp8_linear_forward(
+    x: torch.Tensor, w: torch.Tensor, bias=None, cfg: Optional[_ActiveConfig] = None
+):
+    """Scaled fp8 linear forward (called from the aten::linear impl).
+
+    Composed from the two stateless primitives: quantize x/w with the active
+    scales, run the pre-quantized GEMM with the bias fused into its epilogue.
+    Delayed scaling lets the quantize kernel fold the fused amax into the
+    history ring and publish the next scale in its own last block; dynamic
+    scaling measures the current amax itself. Training quantizes the weight
+    every step (the optimizer bumps its version, so there is no cast cache,
+    matching ``cached_cast``-less behavior).
+    """
+    state = fp8_state()
+    if cfg is None:
+        cfg = _current_config()
+    fmt = cfg.fp8_format.fwd()
+    if cfg.recipe.dynamic:
+        sx = _dynamic_scale(x.reshape(-1, w.size(1)), cfg.recipe, fmt)
+        sw = _dynamic_scale(w, cfg.recipe, fmt)
+        x8, _ = quantize(x, sx.reciprocal(), fmt)
+        w8 = w if _is_fp8(w.dtype) else quantize(w, sw.reciprocal(), fmt)[0]
+        # Bias fuses into the GEMM epilogue (fp32 add before the single bf16
+        # rounding — one rounding fewer than the separate out + bias pass);
+        # None passes through to the kernel's no-bias path.
+        out = mm_fp8(
+            x8.reshape(-1, x8.size(-1)), w8, sx * sw, trans_b=True, bias=bias
+        ).reshape(*x.shape[:-1], w.size(0))
+        return out, sx, sw
+
+    meta = state.get_weight_meta(w, cfg.recipe)
+    if not meta.w.initialized:
+        meta.w.seed(w, fmt)
+    if not meta.x.initialized:
+        meta.x.seed(x, fmt)
+    sx, sw = meta.x.scale.clone(), meta.w.scale.clone()
+    # The clones feed this call's kernels (stream-ordered before the in-kernel
+    # fold overwrites the ring scale slots); the fp8 quantize kernel folds the
+    # amax into the history window and publishes the next scale itself.
+    x8, _ = quantize(x, sx.reciprocal(), fmt, **meta.x.fold_args(fmt))
+    if _is_fp8(w.dtype):
+        w8 = w
+    else:
+        w8, _ = quantize(w, sw.reciprocal(), fmt, **meta.w.fold_args(fmt))
+    out = mm_fp8(
+        x8.reshape(-1, x8.size(-1)), w8, sx * sw, trans_b=True, bias=bias
+    ).reshape(*x.shape[:-1], w.size(0))
+    meta.x.advance()
+    if not _is_fp8(w.dtype):
+        meta.w.advance()
+    return out, sx, sw
+
+
+class _LinearFp8(torch.autograd.Function):
+    """The fp8 linear forward/backward pair (standard Function style).
+
+    The forward runs inside ``fp8_autocast`` and captures the active
+    fmt/recipe/meta on ``ctx``; the backward reads only that captured state, so
+    ``loss.backward()`` may run after the context exits. The gradient is
+    quantized once (E5M2 in hybrid) and both dX/dW GEMMs share it; the output
+    masks come from ``needs_input_grad``.
+    """
+
+    @staticmethod
+    def forward(ctx, x, w, bias):
+        cfg = _current_config()
+        out, sx, sw = fp8_linear_forward(x, w, bias, cfg)
+        ctx.save_for_backward(x, w, sx, sw)
+        ctx.fmt_bwd = cfg.fp8_format.bwd()
+        ctx.recipe = cfg.recipe
+        ctx.is_dynamic = cfg.recipe.dynamic
+        ctx.meta = None if ctx.is_dynamic else _state.get_weight_meta(w, cfg.recipe)
+        return out
+
+    @staticmethod
+    @torch.autograd.function.once_differentiable
+    def backward(ctx, g):
+        x, w, _sx_fwd, _sw_fwd = ctx.saved_tensors
+        fmt = ctx.fmt_bwd
+        # Flatten leading dims (the forward GEMMs ran on [-1, N] / [-1, K]
+        # views; the kernels only accept 2D operands).
+        g2 = g.reshape(-1, g.size(-1))
+        if ctx.is_dynamic:
+            sg = _dynamic_scale(g2, ctx.recipe, fmt)
+            sw = _dynamic_scale(w, ctx.recipe, fmt)
+            sx = _dynamic_scale(x, ctx.recipe, fmt)
+        else:
+            meta = ctx.meta
+            if not meta.g.initialized:
+                meta.g.seed(g2, fmt)
+            sg = meta.g.scale.clone()
+            sw, sx = _sw_fwd, _sx_fwd
+        # Backward GEMMs route through the NT fast path via transposed
+        # quantize outputs: g8 [m,n] with w8T [k,n] (trans_b=True) gives
+        # grad_x, g8T [n,m] with x8T [k,m] gives grad_w — no NN-swap or TT
+        # crosswise kernel in the training path. g is consumed in both
+        # orientations, so quantize_dual's single pass feeds both.
+        # The g quantize folds the gradient amax into its ring in-kernel;
+        # the x8T/w8T orientation copies discard amax (those rings were
+        # folded at forward time).
+        g8, g8T, _ = quantize_dual(g2, sg.reciprocal(), fmt, **meta.g.fold_args(fmt))
+        x8T, _ = quantize(
+            x.reshape(-1, x.size(-1)), sx.reciprocal(), fmt, transposed=True
+        )
+        if _is_fp8(w.dtype):
+            # Pre-quantized weight has no transposed copy: keep the swap
+            # path for grad_x (grad_w is unaffected).
+            grad_x = mm_fp8(g8, w, sg * sw).reshape(x.shape)
+        else:
+            w8T, _ = quantize(w, sw.reciprocal(), fmt, transposed=True)
+            grad_x = mm_fp8(g8, w8T, sg * sw, trans_b=True).reshape(x.shape)
+        grad_w = mm_fp8(g8T, x8T, sg * sx, trans_b=True)  # g8.T @ x8
+        # bias-free linears must not pay the column-sum
+        # reduce: g2.sum(0) is another full read of the gradient.
+        grad_b = g2.sum(0).to(torch.bfloat16) if ctx.needs_input_grad[2] else None
+        if not ctx.is_dynamic:
+            meta.g.advance()
+        return grad_x, grad_w, grad_b
+
+
+# ---------------------------------------------------------------------------
+# aten::linear integration
+# ---------------------------------------------------------------------------
+
+
+def fp8_linear_enable(enabled: bool = True) -> None:
+    """Toggle fp8 dispatch for aten::linear globally (the out-of-region default;
+    ``fp8_autocast`` regions override it thread-locally)."""
+    fp8_state().default_enabled = enabled
+
+
+def fp8_linear_enabled() -> bool:
+    """Whether fp8 dispatch is active right now (region config or global)."""
+    return _active() is not None
+
+
+def _fp8_supported(x: torch.Tensor, w: torch.Tensor) -> bool:
+    """Shape guard for the fp8 path. Unlike a strict 16-alignment requirement,
+    the kernels handle unaligned M/N via boundary checks (slower but correct) —
+    so no whole-call bf16 fallback for small decode batches. Only the K-dimension
+    contraction must match and the weight must be 2D."""
+    return x.dim() >= 2 and w.dim() == 2 and x.size(-1) == w.size(1)
+
+
+def _linear_cuda_impl(x: torch.Tensor, w: torch.Tensor, bias=None):
+    if (
+        _active() is not None
+        and x.dtype is torch.bfloat16
+        and w.dtype is torch.bfloat16
+        and _fp8_supported(x, w)
+    ):
+        return _LinearFp8.apply(x, w, bias)
+    return torch.ops.aten.linear.default.redispatch(
+        torch._C.DispatchKeySet(torch._C.DispatchKey.CompositeImplicitAutograd),
+        x,
+        w,
+        bias,
+    )
+
+
+_lib = Library("aten", "IMPL", "CUDA")
+_lib.impl("linear", _linear_cuda_impl)
+# Also replace torch's generated linear autograd formula (which would call
+# aten::linear_backward after the fp8_autocast region exits). The fp8 backward
+# is owned by _LinearFp8 with state captured at forward time, so loss.backward()
+# works wherever it is called; the CUDA registration still covers inference_mode.
+_lib_autograd = Library("aten", "IMPL", "AutogradCUDA")
+_lib_autograd.impl("linear", _linear_cuda_impl)

astrai/extension/lib/__init__.py

@@ -0,0 +1 @@
+"""Compiled CUDA kernel modules (``*.so``) live here, kept separate from Python source."""

astrai/extension/loader.py

@@ -1,36 +1,83 @@
 """Dynamic discovery and loading of compiled CUDA kernel modules.
 
-Each kernel is registered in ``csrc/build.py`` and built into a ``.so`` placed
-in this package directory. On import we try to load each one; kernels that
-failed to build (or are running on a CPU-only machine) are marked unavailable
-so the wrapper functions can fall back to ``torch`` SDPA.
+Each kernel is built by the CMake build in ``csrc/CMakeLists.txt`` into a
+``.so`` placed in ``astrai/extension/lib/`` — the module name equals the
+``.so`` name equals the pybind name (e.g. ``attn_decode``, defined via
+``TORCH_EXTENSION_NAME``). ``KERNEL_NAMES`` is discovered automatically from
+the ``.so`` files present, so adding a kernel to the CMake ``KERNELS``
+registry needs no change here.
+
+Loading is **lazy and centralized**: module names are discovered eagerly
+(cheap glob), but each ``.so`` is imported on first use via the single
+``get_module`` accessor, then cached. The wrapper modules (``ops/*.py``) never
+touch the internals or keep their own caches — they call ``get_module(name)``
+(or ``is_available(name)`` when a torch fallback is acceptable). A kernel that
+failed to build (or is running on a CPU-only machine) is ``None`` in the cache,
+so ``is_available`` returns ``False`` and ``get_module`` raises a clear error.
 """
 
+import glob
 import importlib
 import logging
+import os
 
 logger = logging.getLogger(__name__)
 
-KERNEL_NAMES = ["attn_decode", "attn_prefill", "attn_paged_decode"]
+_LIB_DIR = os.path.join(os.path.dirname(__file__), "lib")
+
+
+def _discover_kernel_names() -> list[str]:
+    """Return the module names of the compiled kernel ``.so`` files in lib/."""
+    names: list[str] = []
+    for path in glob.glob(os.path.join(_LIB_DIR, "*.so")):
+        # strip the "<soabi>.so" suffix, e.g. attn_decode.cpython-312-...so
+        names.append(os.path.basename(path).split(".", 1)[0])
+    return sorted(names)
+
+
+KERNEL_NAMES = _discover_kernel_names()
 
 _available: dict[str, bool] = {}
 _modules: dict[str, object] = {}
 
-for _name in KERNEL_NAMES:
-    try:
-        _mod = importlib.import_module(f".{_name}", package=__package__)
-        _available[_name] = True
-        _modules[_name] = _mod
-    except ImportError:
-        _available[_name] = False
-        _modules[_name] = None
+
+def _try_load(name: str) -> object:
+    """Import and cache the ``name`` kernel module (lazy, one attempt).
+
+    Returns the module, or ``None`` if it is unavailable. Cached so each
+    ``.so`` is imported at most once per process.
+    """
+    if name not in _modules:
+        try:
+            _modules[name] = importlib.import_module(
+                f".lib.{name}", package=__package__
+            )
+            _available[name] = True
+        except ImportError:
+            logger.warning("kernel '%s' failed to import; marking unavailable", name)
+            _modules[name] = None
+            _available[name] = False
+    return _modules[name]
 
 
 def is_available(name: str) -> bool:
-    """Return ``True`` if the compiled kernel ``name`` was loaded."""
+    """Return ``True`` if the compiled kernel ``name`` could be loaded."""
+    if name not in _available:
+        _try_load(name)
     return _available.get(name, False)
 
 
 def get_module(name: str) -> object:
-    """Return the loaded kernel module for ``name``, or ``None`` if unavailable."""
-    return _modules.get(name)
+    """Return the loaded kernel module for ``name``, importing it on first use.
+
+    Raises ``RuntimeError`` if the kernel is unavailable (not built, or failed
+    to import) — callers that can tolerate a torch fallback should check
+    ``is_available(name)`` first instead.
+    """
+    mod = _try_load(name)
+    if mod is None:
+        raise RuntimeError(
+            f"CUDA kernel '{name}' is not available. "
+            f"Build with CSRC_KERNELS=true (or use the torch-native fallback)."
+        )
+    return mod

astrai/extension/ops.py

@@ -1,246 +0,0 @@
-"""GQA attention wrapper functions — one entry point per compiled kernel.
-
-Each wrapper dispatches to its CUDA kernel (loaded in ``loader.py``) when
-available, otherwise falls back to ``torch`` SDPA.
-
-Interface (all functions):
-    causal_offset: -1 = non-causal; >=0 = absolute position of first Q token
-    mask:       2D [batch, kv_len] or 3D [batch, q_len, kv_len] (bool)
-    scale:      0.0 = auto (1/sqrt(head_dim)); >0 = explicit
-    layout:     "bhld" (default) or "blhd"
-
-Add new kernel wrappers here; split into per-variant files only if this file
-grows large.
-"""
-
-import math
-
-import torch
-import torch.nn.functional as F
-
-from astrai.extension.loader import _available, _modules
-
-_LAYOUT_CODES: dict[str, int] = {"bhld": 0, "blhd": 1}
-
-
-def _parse_layout(layout: str | int) -> int:
-    if isinstance(layout, int):
-        return layout
-    code = _LAYOUT_CODES.get(layout.lower())
-    if code is None:
-        raise ValueError(
-            f"unknown layout '{layout}', expected one of {list(_LAYOUT_CODES)}"
-        )
-    return code
-
-
-def _to_bhld(t: torch.Tensor, layout: int) -> torch.Tensor:
-    """Normalize to b h l d view. Zero-copy transpose if layout==1 (b l h d)."""
-    if layout == 1:
-        return t.transpose(1, 2)
-    return t
-
-
-def _expand_kv_heads(
-    k: torch.Tensor, v: torch.Tensor, q_head: int
-) -> tuple[torch.Tensor, torch.Tensor]:
-    """Expand K/V heads to match Q heads for GQA fallback."""
-    kv_head = k.size(1)
-    if kv_head == q_head:
-        return k, v
-    group = q_head // kv_head
-    k = k.repeat_interleave(group, dim=1)
-    v = v.repeat_interleave(group, dim=1)
-    return k, v
-
-
-def _build_attn_mask(
-    q: torch.Tensor,
-    k: torch.Tensor,
-    mask: torch.Tensor | None,
-    causal_offset: int,
-    scale: float,
-) -> tuple[torch.Tensor | None, float]:
-    """Build SDPA-compatible attn_mask + resolved scale.
-
-    q and k must already be in b h l d layout.
-    Causal and mask can coexist: causal sets -inf above the diagonal, mask
-    sets -inf for padded positions. Both are OR'd into a single bool mask.
-    """
-    q_len = q.size(2)
-    kv_len = k.size(2)
-    head_dim = q.size(3)
-    resolved_scale = scale if scale and scale > 0 else 1.0 / math.sqrt(head_dim)
-
-    attn_mask = None
-
-    if mask is not None:
-        if mask.dim() == 2:
-            # [batch, kv_len] → [batch, 1, 1, kv_len]
-            attn_mask = mask[:, None, None, :]
-        elif mask.dim() == 3:
-            # [batch, q_len, kv_len] → [batch, 1, q_len, kv_len]
-            attn_mask = mask[:, None, :, :]
-        else:
-            raise ValueError(f"mask must be 2D or 3D, got {mask.dim()}D")
-
-    if causal_offset >= 0:
-        batch = q.size(0)
-        # q row i attends to kv cols 0..(causal_offset + i)
-        q_idx = torch.arange(q_len, device=q.device).unsqueeze(1)  # [q_len, 1]
-        kv_idx = torch.arange(kv_len, device=q.device).unsqueeze(0)  # [1, kv_len]
-        causal_bool = kv_idx > (causal_offset + q_idx)  # True = masked out
-        causal_mask = causal_bool.unsqueeze(0).expand(
-            batch, -1, -1
-        )  # [batch, q_len, kv_len]
-        causal_mask = causal_mask[:, None, :, :]  # [batch, 1, q_len, kv_len]
-
-        if attn_mask is not None:
-            attn_mask = attn_mask | causal_mask
-        else:
-            attn_mask = causal_mask
-
-    return attn_mask, resolved_scale
-
-
-def _torch_fallback(
-    q: torch.Tensor,
-    k: torch.Tensor,
-    v: torch.Tensor,
-    mask: torch.Tensor | None,
-    causal_offset: int,
-    scale: float,
-    q_layout: int,
-    kv_layout: int | None = None,
-) -> torch.Tensor:
-    """Reference attention via ``scaled_dot_product_attention``.
-
-    q_layout / kv_layout: 0 = b h l d, 1 = b l h d.
-    If kv_layout is None, uses q_layout (Q and K/V share the same layout).
-    """
-    if kv_layout is None:
-        kv_layout = q_layout
-    q = _to_bhld(q, q_layout)
-    k = _to_bhld(k, kv_layout)
-    v = _to_bhld(v, kv_layout)
-    k, v = _expand_kv_heads(k, v, q.size(1))
-    attn_mask, resolved_scale = _build_attn_mask(q, k, mask, causal_offset, scale)
-    out = F.scaled_dot_product_attention(
-        q, k, v, attn_mask=attn_mask, is_causal=False, scale=resolved_scale
-    )
-    # Restore Q's original layout
-    if q_layout == 1:
-        out = out.transpose(1, 2)
-    return out
-
-
-def _gather_kv_from_pages(
-    page_table: torch.Tensor,
-    k_cache: torch.Tensor,
-    v_cache: torch.Tensor,
-    page_size: int,
-    kv_len: int,
-) -> tuple[torch.Tensor, torch.Tensor]:
-    """Gather contiguous K/V from paged cache for torch SDPA fallback.
-
-    Shapes:
-        page_table : [batch, max_pages] (int64)
-        k_cache    : [n_pages, page_size, n_kv_heads, head_dim]
-        v_cache    : same as k_cache
-    Returns:
-        k, v : [batch, kv_len, n_kv_heads, head_dim]  (b l h d)
-    """
-    batch, max_pages = page_table.shape
-    _, ps, n_kv_heads, head_dim = k_cache.shape
-    if ps != page_size:
-        raise ValueError(f"k_cache page_size mismatch: {ps} vs {page_size}")
-
-    # Vectorized gather: build physical page + offset indices, then advanced-index
-    positions = torch.arange(kv_len, device=page_table.device)
-    logical_pages = positions // page_size  # [kv_len]
-    page_offsets = positions % page_size  # [kv_len]
-
-    phys_pages = page_table[:, logical_pages]  # [batch, kv_len]
-    # k_cache[phys_pages, page_offsets] → [batch, kv_len, n_kv_heads, head_dim] (b l h d)
-    k = k_cache[phys_pages, page_offsets]
-    v = v_cache[phys_pages, page_offsets]
-    return k, v
-
-
-def attn_decode(
-    q: torch.Tensor,
-    k: torch.Tensor,
-    v: torch.Tensor,
-    mask: torch.Tensor | None = None,
-    causal_offset: int = -1,
-    scale: float = 0.0,
-    layout: str = "bhld",
-) -> torch.Tensor:
-    li = _parse_layout(layout)
-    if _available["attn_decode"]:
-        return _modules["attn_decode"].attn_decode(
-            q,
-            k,
-            v,
-            mask=mask,
-            causal_offset=causal_offset,
-            scale=scale,
-            layout=li,
-        )
-    return _torch_fallback(q, k, v, mask, causal_offset, scale, q_layout=li)
-
-
-def attn_prefill(
-    q: torch.Tensor,
-    k: torch.Tensor,
-    v: torch.Tensor,
-    mask: torch.Tensor | None = None,
-    causal_offset: int = -1,
-    scale: float = 0.0,
-    layout: str = "bhld",
-) -> torch.Tensor:
-    li = _parse_layout(layout)
-    if _available["attn_prefill"]:
-        return _modules["attn_prefill"].attn_prefill(
-            q,
-            k,
-            v,
-            mask=mask,
-            causal_offset=causal_offset,
-            scale=scale,
-            layout=li,
-        )
-    return _torch_fallback(q, k, v, mask, causal_offset, scale, q_layout=li)
-
-
-def attn_paged_decode(
-    q: torch.Tensor,
-    page_table: torch.Tensor,
-    k_cache: torch.Tensor,
-    v_cache: torch.Tensor,
-    page_size: int,
-    kv_len: int,
-    mask: torch.Tensor | None = None,
-    causal_offset: int = -1,
-    scale: float = 0.0,
-    layout: str = "bhld",
-) -> torch.Tensor:
-    li = _parse_layout(layout)
-    if _available["attn_paged_decode"]:
-        return _modules["attn_paged_decode"].attn_paged_decode(
-            q,
-            page_table,
-            k_cache,
-            v_cache,
-            page_size,
-            kv_len,
-            mask=mask,
-            causal_offset=causal_offset,
-            scale=scale,
-            layout=li,
-        )
-    # Gathered K/V are always b l h d
-    k, v = _gather_kv_from_pages(page_table, k_cache, v_cache, page_size, kv_len)
-    return _torch_fallback(
-        q, k, v, mask, causal_offset, scale, q_layout=li, kv_layout=1
-    )

astrai/extension/ops/__init__.py

@@ -0,0 +1,19 @@
+"""Stateless wrappers around compiled extension kernels."""
+
+from astrai.extension.ops.attention import (
+    TensorLayout,
+    attn_decode,
+    attn_paged_decode,
+    attn_paged_prefill,
+    attn_prefill,
+)
+from astrai.extension.ops.rotary import rotary_emb
+
+__all__ = [
+    "TensorLayout",
+    "attn_decode",
+    "attn_paged_decode",
+    "attn_paged_prefill",
+    "attn_prefill",
+    "rotary_emb",
+]

astrai/extension/ops/attention.py

@@ -0,0 +1,192 @@
+"""Attention kernel wrapper functions - one entry point per compiled kernel.
+
+Each wrapper calls its CUDA kernel directly. If the kernel is not
+available, raises ``RuntimeError``. Fallback to torch SDPA is the
+responsibility of the attention backend, not this module.
+
+Layout convention: all q/k/v are ``[batch, seq_len, n_heads, head_dim]``
+(blhd). Scale is always ``1/sqrt(head_dim)``.
+
+Interface (all functions):
+    is_causal: True = causal mask; False = non-causal
+    mask:      2D [batch, kv_len] or 3D [batch, q_len, kv_len] (bool, True=keep)
+"""
+
+import enum
+from typing import Optional
+
+import torch
+
+from astrai.extension.loader import get_module
+
+
+class TensorLayout(enum.IntEnum):
+    """Q/K/V tensor layout, mirrors the C++ ``TensorLayout`` enum in ``attn_common.h``.
+
+    Kernels internally operate on BHLD; BLHD inputs are transposed at entry.
+    """
+
+    BHLD = 0  # [batch, n_heads, seq_len, head_dim]
+    BLHD = 1  # [batch, seq_len, n_heads, head_dim]
+
+
+def attn_decode(
+    q: torch.Tensor,
+    k: torch.Tensor,
+    v: torch.Tensor,
+    mask: Optional[torch.Tensor] = None,
+    is_causal: bool = False,
+) -> torch.Tensor:
+    """GQA decode attention (q_len == 1).
+
+    Args:
+        q: [batch, 1, n_heads, head_dim] (blhd, bf16)
+        k: [batch, kv_len, n_kv_heads, head_dim] (blhd, bf16)
+        v: [batch, kv_len, n_kv_heads, head_dim] (blhd, bf16)
+        mask: 2D [batch, kv_len] or 3D [batch, 1, kv_len] (bool, True=keep)
+        is_causal: apply causal mask
+
+    Returns:
+        [batch, 1, n_heads, head_dim] (blhd, bf16)
+    """
+    mod = get_module("attn_decode")
+    causal_offset = (k.size(1) - 1) if is_causal else -1
+    return mod.attn_decode(
+        q, k, v, mask=mask, causal_offset=causal_offset, layout=TensorLayout.BLHD
+    )
+
+
+def attn_prefill(
+    q: torch.Tensor,
+    k: torch.Tensor,
+    v: torch.Tensor,
+    mask: Optional[torch.Tensor] = None,
+    is_causal: bool = False,
+) -> torch.Tensor:
+    """GQA prefill attention (q_len > 1).
+
+    Args:
+        q: [batch, q_len, n_heads, head_dim] (blhd, bf16)
+        k: [batch, kv_len, n_kv_heads, head_dim] (blhd, bf16)
+        v: [batch, kv_len, n_kv_heads, head_dim] (blhd, bf16)
+        mask: 2D [batch, kv_len] or 3D [batch, q_len, kv_len] (bool, True=keep)
+        is_causal: apply causal mask
+
+    Returns:
+        [batch, q_len, n_heads, head_dim] (blhd, bf16)
+    """
+    mod = get_module("attn_prefill")
+    causal_offset = (k.size(1) - q.size(1)) if is_causal else -1
+    return mod.attn_prefill(
+        q, k, v, mask=mask, causal_offset=causal_offset, layout=TensorLayout.BLHD
+    )
+
+
+def attn_paged_decode(
+    q: torch.Tensor,
+    k_cache: torch.Tensor,
+    v_cache: torch.Tensor,
+    req_to_token: torch.Tensor,
+    req_pool_indices: torch.Tensor,
+    kv_indptr: torch.Tensor,
+    new_k: Optional[torch.Tensor] = None,
+    new_v: Optional[torch.Tensor] = None,
+    mask: Optional[torch.Tensor] = None,
+    is_causal: bool = False,
+    o_part_buf: Optional[torch.Tensor] = None,
+    ml_part_buf: Optional[torch.Tensor] = None,
+    out_buf: Optional[torch.Tensor] = None,
+) -> torch.Tensor:
+    """SGLang-style paged decode (q_len == 1, flat KV pool).
+
+    Reads K/V directly from a flat pool [size, kv_head, head_dim] via
+    req_to_token indirect indexing.  Each request has its own seq_len
+    (from kv_indptr), eliminating padding waste.
+
+    Args:
+        q: [batch, n_heads, head_dim] (bf16, 3D — no seq dim)
+        k_cache: [pool_size, n_kv_heads, head_dim] (bf16, flat)
+        v_cache: same as k_cache
+        req_to_token: [num_reqs, max_context_len] (int32) — token -> slot
+        req_pool_indices: [batch] (int32) — rows into req_to_token
+        kv_indptr: [batch+1] (int32) — prefix sum of per-request seq_lens
+        new_k: current-token K to append, [batch, n_kv_heads, head_dim]
+        new_v: current-token V to append, same shape as new_k
+        mask: 2D [batch, max_context_len] (bool, True=keep) or None
+        is_causal: apply causal mask
+        o_part_buf: pre-allocated split-KV o partial buffer (workflow bypass)
+        ml_part_buf: pre-allocated split-KV m/l buffer (workflow bypass)
+        out_buf: pre-allocated output buffer [batch, n_heads, head_dim] (graph-safe)
+
+    Returns:
+        [batch, n_heads, head_dim] (bf16, 3D)
+    """
+    mod = get_module("attn_paged_decode")
+    causal_offset = 0 if is_causal else -1
+    return mod.attn_paged_decode(
+        q,
+        k_cache,
+        v_cache,
+        req_to_token,
+        req_pool_indices,
+        kv_indptr,
+        new_k=new_k,
+        new_v=new_v,
+        mask=mask,
+        causal_offset=causal_offset,
+        o_part_buf=o_part_buf,
+        ml_part_buf=ml_part_buf,
+        out_buf=out_buf,
+    )
+
+
+def attn_paged_prefill(
+    q: torch.Tensor,
+    k_cache: torch.Tensor,
+    v_cache: torch.Tensor,
+    req_to_token: torch.Tensor,
+    req_pool_indices: torch.Tensor,
+    kv_indptr: torch.Tensor,
+    qo_indptr: torch.Tensor,
+    q_tile_to_batch: torch.Tensor,
+    q_tile_to_index: torch.Tensor,
+    mask: Optional[torch.Tensor] = None,
+    is_causal: bool = False,
+) -> torch.Tensor:
+    """SGLang-style paged prefill (ragged batch, flat KV pool).
+
+    Reads K/V directly from a flat pool [size, kv_head, head_dim] via
+    req_to_token.  Supports ragged batches: each request has its own
+    q_len and kv_len, addressed via qo_indptr and kv_indptr.
+
+    Args:
+        q: [total_q, n_heads, head_dim] (bf16, 3D — flattened across requests)
+        k_cache: [pool_size, n_kv_heads, head_dim] (bf16, flat)
+        v_cache: same as k_cache
+        req_to_token: [num_reqs, max_context_len] (int32)
+        req_pool_indices: [batch] (int32)
+        kv_indptr: [batch+1] (int32) — prefix sum of per-request kv_lens
+        qo_indptr: [batch+1] (int32) — prefix sum of per-request q_lens
+        q_tile_to_batch: [num_q_tiles] (int32) — request index per Q tile
+        q_tile_to_index: [num_q_tiles] (int32) — local Q tile index per request
+        mask: 4D [batch, 1, q_len, kv_len] (bool, True=keep) or None
+        is_causal: apply causal mask
+
+    Returns:
+        [total_q, n_heads, head_dim] (bf16, 3D)
+    """
+    mod = get_module("attn_paged_prefill")
+    causal_offset = 0 if is_causal else -1
+    return mod.attn_paged_prefill(
+        q,
+        k_cache,
+        v_cache,
+        req_to_token,
+        req_pool_indices,
+        kv_indptr,
+        qo_indptr,
+        q_tile_to_batch,
+        q_tile_to_index,
+        mask,
+        causal_offset=causal_offset,
+    )

astrai/extension/ops/fp8.py

@@ -0,0 +1,116 @@
+"""FP8 CUDA kernel interface adapter (the only module touching the pybind).
+
+Attention-style thin wrappers: one Python entry per binding, called directly
+— no torch.library dispatch layer. Optional arguments (``ring_state``,
+``bias``) keep native Optional semantics at the pybind boundary, and
+in-place buffer updates (the delayed-scaling ring fold, like attention's
+KV-cache appends) happen on-stream without mutation declarations. CUDA-only:
+non-CUDA or unsupported inputs raise from the binding's TORCH_CHECKs.
+
+- ``quantize(x, scale, fmt, transposed=False) -> (x8|x8T, amax)`` — BF16/FP16/FP32
+  → FP8 with fused amax (``transposed`` picks the orientation; arity is fixed)
+- ``quantize_dual(x, scale, fmt) -> (x8, x8T, amax)`` — both orientations, one read
+- ``mm_fp8(a8, b8, sa, sb) -> out`` — pre-quantized FP8 GEMM (BF16 output)
+
+``scale`` is the quantization multiplier (device scalar); ``fmt`` is
+``"e4m3"`` or ``"e5m2"``. ``amax`` values are *returned*, never passed as
+output arguments.
+
+Policy (scales, amax history, delayed scaling, autocast) lives in ``fp8.py``;
+this module is stateless.
+"""
+
+from typing import Optional, Tuple
+
+import torch
+
+from astrai.extension.loader import get_module
+
+# fmt string -> kernel int (0 = E4M3, 1 = E5M2)
+_FMT_TO_INT = {"e4m3": 0, "e5m2": 1}
+
+
+def _fmt_int(fmt: str) -> int:
+    try:
+        return _FMT_TO_INT[fmt]
+    except KeyError:
+        raise ValueError(f"unsupported fp8 format {fmt!r} (expected 'e4m3' or 'e5m2')")
+
+
+def quantize(
+    x: torch.Tensor,
+    scale: torch.Tensor,
+    fmt: str = "e4m3",
+    transposed: bool = False,
+    ring_state: Optional[torch.Tensor] = None,
+    hist_idx: int = 0,
+    fp8_max: float = 448.0,
+    pow2_margin: float = 1.0,
+) -> Tuple[torch.Tensor, torch.Tensor]:
+    """Float (bf16/fp16/fp32) -> FP8 quantize with fused amax.
+
+    ``scale`` is the quantization multiplier (device scalar); ``fmt`` selects
+    E4M3 or E5M2. ``amax`` is a fresh 1-element float32 tensor.
+    ``transposed=True`` swaps ``x8`` for ``x8T``, the ``[cols][rows]``
+    row-major transpose of the quantized input — the K-contiguous operand
+    orientation NT GEMMs want — at the same 2-tuple arity.
+
+    ``ring_state`` (a 1D float32 CUDA buffer laid out
+    ``[hist n | scale | legacy | amax | done]``) switches on the in-kernel
+    delayed-scaling fold: the kernel's last block folds the amax into
+    ``hist[hist_idx]`` and publishes the next scale as
+    ``max(hist) / fp8_max / pow2_margin`` — the returned ``amax`` is then the
+    self-cleaned persistent slot (reads zero). None keeps the classic
+    fresh-amax return.
+    """
+    return get_module("fp8_ops").quantize(
+        x,
+        scale,
+        _fmt_int(fmt),
+        transposed,
+        ring_state,
+        hist_idx,
+        fp8_max,
+        pow2_margin,
+    )
+
+
+def quantize_dual(
+    x: torch.Tensor,
+    scale: torch.Tensor,
+    fmt: str = "e4m3",
+    ring_state: Optional[torch.Tensor] = None,
+    hist_idx: int = 0,
+    fp8_max: float = 448.0,
+    pow2_margin: float = 1.0,
+) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
+    """Dual-orientation quantize: one read of ``x`` produces both the
+    row-major ``x8`` and its transposed ``x8T`` (plus ``amax``), for tensors
+    consumed by GEMMs in both orientations (backward ``g``).
+
+    ``ring_state`` switches on the in-kernel delayed-scaling fold exactly as
+    in :func:`quantize`.
+    """
+    return get_module("fp8_ops").quantize_dual(
+        x, scale, _fmt_int(fmt), ring_state, hist_idx, fp8_max, pow2_margin
+    )
+
+
+def mm_fp8(
+    a: torch.Tensor,
+    b: torch.Tensor,
+    scale: torch.Tensor,
+    trans_a: bool = False,
+    trans_b: bool = False,
+    bias: Optional[torch.Tensor] = None,
+) -> torch.Tensor:
+    """Pre-quantized FP8 GEMM: ``a @ b * scale (+ bias)``.
+
+    ``a``/``b`` must be FP8 tensors of the same format, 2D or 3D (batched,
+    matmul-style broadcast on the batch dim). Inner-transposed views (e.g.
+    ``x.t()``) fold into the layout at zero copy. ``scale`` is their combined
+    dequantization scale. ``bias`` (CUDA bf16 1D of length n) adds inside the
+    kernel epilogue in fp32 — no separate elementwise pass. The result is
+    BF16; FP8 output is a separate quantize operation.
+    """
+    return get_module("fp8_ops").mm_fp8(a, b, scale, trans_a, trans_b, bias)

astrai/extension/ops/rotary.py

@@ -0,0 +1,31 @@
+"""Rotary embedding CUDA kernel wrapper.
+
+Calls the compiled CUDA kernel directly. If the kernel is not available,
+raises ``RuntimeError``. Fallback to torch complex multiply is the
+responsibility of ``astrai.extension.backend.rotary.apply_rotary_emb``.
+
+Layout: x is packed [tokens, n_heads, head_dim] or dense
+[batch, seq_len, n_heads, head_dim]. ``freqs_cis`` has matching token axes.
+"""
+
+import torch
+
+from astrai.extension.loader import get_module
+
+
+def rotary_emb(x: torch.Tensor, freqs_cis: torch.Tensor) -> torch.Tensor:
+    """Fused rotary embedding kernel.
+
+    Args:
+        x: packed 3D or dense 4D bf16 tensor.
+        freqs_cis: matching token axes followed by [head_dim/2, 2].
+
+    Returns:
+        Tensor with the same shape as ``x``.
+    """
+    mod = get_module("rotary_emb")
+    if not x.is_contiguous():
+        x = x.contiguous()
+    if not freqs_cis.is_contiguous():
+        freqs_cis = freqs_cis.contiguous()
+    return mod.rotary_emb(x, freqs_cis)

astrai/factory.py

@@ -13,41 +13,63 @@ from typing import (
     Type,
     TypeVar,
     Union,
+    get_args,
+    get_origin,
 )
-from typing import get_args as _get_args
-from typing import get_origin as _get_origin
 
 T = TypeVar("T")
 
 
-def _resolve_type(
+def _resolve_base_type(
     arg: Union[Type, str, ForwardRef], factory_cls: type
 ) -> Optional[Type]:
-    """Resolve a generic type-arg (str forward-ref, ForwardRef, or class)."""
-    if not isinstance(arg, (str, ForwardRef)):
+    """Resolve the generic type-arg T to a concrete class.
+
+    - Concrete class (``BaseFactory[MyBase]``): returned directly.
+    - Forward reference (``BaseFactory["MyBase"]``): ``Base["X"]``
+      produces a ``ForwardRef("X")`` at class-creation time.  We
+      extract the name and evaluate it in the factory module's
+      global namespace — the same mechanism ``typing.get_type_hints``
+      uses internally.
+    """
+    if isinstance(arg, type):
         return arg
 
-    name = arg if isinstance(arg, str) else arg.__forward_arg__
-    if name == factory_cls.__name__:
-        return factory_cls
+    if isinstance(arg, str):
+        name = arg
+    elif isinstance(arg, ForwardRef):
+        name = arg.__forward_arg__
+    else:
+        return None
 
     mod = sys.modules.get(factory_cls.__module__)
     if mod is None:
         return None
-    ns = vars(mod)
+    try:
+        return eval(name, vars(mod))  # noqa: S307
+    except NameError:
+        return None
 
-    if isinstance(arg, ForwardRef):
-        return arg._evaluate(ns, None, recursive_guard=frozenset())
 
-    return ns.get(name)
+def _validate_component(component_cls: Type, base: Optional[Type]) -> None:
+    """Validate that *component_cls* inherits from *base*.
+
+    No-op when *base* is ``None`` (e.g. forward-ref resolution failed).
+    """
+    if base is not None and not issubclass(component_cls, base):
+        raise TypeError(f"{component_cls.__name__} must inherit from {base.__name__}")
 
 
 class BaseFactory(ABC, Generic[T]):
-    """Generic factory with decorator-based component registration.
+    """Generic factory with decorator-based registration.
+
+    Create a factory by subclassing with the desired base type::
 
         class MyFactory(BaseFactory[MyBase]):
             pass
 
+    Register components with the ``register`` decorator::
+
         @MyFactory.register("custom")
         class CustomComponent(MyBase):
             ...
@@ -64,10 +86,10 @@ class BaseFactory(ABC, Generic[T]):
     def __init_subclass__(cls, **kwargs):
         super().__init_subclass__(**kwargs)
         for orig_base in getattr(cls, "__orig_bases__", ()):
-            if _get_origin(orig_base) is BaseFactory:
-                (arg,) = _get_args(orig_base)
+            if get_origin(orig_base) is BaseFactory:
+                (arg,) = get_args(orig_base)
                 cls._entries = {}
-                cls._component_base = _resolve_type(arg, cls)
+                cls._component_base = _resolve_base_type(arg, cls)
                 return
 
     @classmethod
@@ -79,7 +101,7 @@ class BaseFactory(ABC, Generic[T]):
         """
 
         def decorator(component_cls: Type[T]) -> Type[T]:
-            cls._validate_component(component_cls)
+            _validate_component(component_cls, cls._component_base)
             if name in cls._entries:
                 raise ValueError(f"Component '{name}' is already registered")
             cls._entries[name] = component_cls
@@ -92,12 +114,11 @@ class BaseFactory(ABC, Generic[T]):
         """Create a component instance by name, filtering kwargs to match
         the component's ``__init__`` signature.
         """
-        entry = cls._entries.get(name)
-        if entry is None:
+        component_cls = cls._entries.get(name)
+        if component_cls is None:
             raise ValueError(
                 f"Unknown component: '{name}'. Supported types: {sorted(cls._entries)}"
             )
-        component_cls = entry
         sig = inspect.signature(component_cls.__init__)
         has_var_kwargs = any(
             p.kind == inspect.Parameter.VAR_KEYWORD for p in sig.parameters.values()
@@ -111,18 +132,6 @@ class BaseFactory(ABC, Generic[T]):
             kwargs = {k: v for k, v in kwargs.items() if k in valid}
         return component_cls(*args, **kwargs)
 
-    @classmethod
-    def _validate_component(cls, component_cls: Type[T]):
-        """Validate the decorated class inherits from the factory's base type.
-
-        Override for custom validation beyond ``issubclass``.
-        """
-        base = cls._component_base
-        if base is not None and not issubclass(component_cls, base):
-            raise TypeError(
-                f"{component_cls.__name__} must inherit from {base.__name__}"
-            )
-
     @classmethod
     def get_component_class(cls, name: str) -> Type[T]:
         """Get the registered component class without instantiating it."""

astrai/inference/__init__.py

@@ -1,105 +1,33 @@
 """Inference module for continuous batching.
 
-Layers:
-  - core/:        Core inference loop (cache, executor, scheduler, task)
-  - api/:         HTTP orchestration (ProtocolHandler, server)
-  - protocols/:   Response builders (OpenAI, Anthropic)
-  - transport/:   SSE transport utilities
-  - engine.py:    Facade (InferenceEngine), Value Object (GenerationRequest)
-  - sample.py:    Strategy pattern (TemperatureStrategy, TopKStrategy, TopPStrategy, FrequencyPenaltyStrategy)
+Subpackages:
+  - cache/:     KV cache (buffers, strategies, pool)
+  - runtime/:   Execution + sampling (executor, CUDA graph, sampling strategies)
+  - task/:      Request lifecycle + performance metrics
+  - network/:   HTTP protocol handling (server, protocol, OpenAI/Anthropic builders)
+
+Modules:
+  - scheduler.py:  Continuous batching loop
+  - workspace.py:  Pre-allocated GPU buffers
+  - engine.py:     Facade (InferenceEngine)
 """
 
-from astrai.inference.api import (
-    AnthropicMessage,
-    BaseToolParser,
-    ChatCompletionRequest,
-    ChatMessage,
-    FunctionDef,
-    GenContext,
-    MessagesRequest,
-    ProtocolHandler,
-    SimpleJsonToolParser,
-    StopChecker,
-    ToolDef,
-    ToolParserFactory,
-    get_app,
-    run_server,
-)
-from astrai.inference.api.anthropic import AnthropicResponseBuilder
-from astrai.inference.api.openai import OpenAIResponseBuilder
-from astrai.inference.core import (
-    STOP,
-    Allocator,
-    CacheView,
-    ContiguousCache,
-    ContiguousCacheView,
-    Executor,
-    InferenceScheduler,
-    KVCache,
-    PageCache,
-    PageCacheView,
-    PagePool,
-    PrefixCache,
-    Storage,
-    Task,
-    TaskManager,
-    TaskStatus,
-    TaskTable,
-    page_hash,
-)
-from astrai.inference.engine import GenerationRequest, InferenceEngine
-from astrai.inference.sample import (
-    BaseSamplingStrategy,
-    FrequencyPenaltyStrategy,
-    SamplingPipeline,
-    TemperatureStrategy,
-    TopKStrategy,
-    TopPStrategy,
-    sample,
-)
+from astrai.inference.engine import InferenceEngine
+from astrai.inference.network import get_app, run_server
+from astrai.inference.runtime.executor import Executor
+from astrai.inference.runtime.sample import sample
+from astrai.inference.scheduler import InferenceScheduler
+from astrai.inference.task import STOP, Task, TaskManager, TaskStatus
 
 __all__ = [
     "InferenceEngine",
-    "GenerationRequest",
     "InferenceScheduler",
     "Executor",
     "STOP",
     "Task",
     "TaskManager",
     "TaskStatus",
-    "Allocator",
-    "CacheView",
-    "KVCache",
-    "ContiguousCache",
-    "ContiguousCacheView",
-    "PageCache",
-    "PageCacheView",
-    "PagePool",
-    "PrefixCache",
-    "Storage",
-    "TaskTable",
-    "page_hash",
     "sample",
-    "BaseSamplingStrategy",
-    "TemperatureStrategy",
-    "TopKStrategy",
-    "TopPStrategy",
-    "FrequencyPenaltyStrategy",
-    "SamplingPipeline",
-    "ProtocolHandler",
-    "StopChecker",
-    "GenContext",
-    "BaseToolParser",
-    "SimpleJsonToolParser",
-    "ToolParserFactory",
-    "OpenAIResponseBuilder",
-    "AnthropicResponseBuilder",
-    "ChatMessage",
-    "ChatCompletionRequest",
-    "FunctionDef",
-    "ToolDef",
-    "AnthropicMessage",
-    "MessagesRequest",
     "get_app",
     "run_server",
 ]

astrai/inference/cache/__init__.py

@@ -0,0 +1,27 @@
+"""KV cache subsystem: buffers, strategies, pool management."""
+
+from astrai.inference.cache.buffer import KVCache, KVStorage, ReqToTokenPool
+from astrai.inference.cache.pool import PagePool, TaskCacheManager, page_hash
+from astrai.inference.cache.strategy import (
+    AllocationStrategy,
+    Allocator,
+    ContiguousStrategy,
+    PagedStrategy,
+    RadixCache,
+    TaskCacheState,
+)
+
+__all__ = [
+    "KVCache",
+    "KVStorage",
+    "ReqToTokenPool",
+    "Allocator",
+    "RadixCache",
+    "TaskCacheState",
+    "AllocationStrategy",
+    "ContiguousStrategy",
+    "PagedStrategy",
+    "PagePool",
+    "TaskCacheManager",
+    "page_hash",
+]

astrai/inference/cache/buffer.py

@@ -0,0 +1,96 @@
+"""Physical KV cache buffers.
+
+Layer 1 — ``KVStorage``:   flat token-level K/V GPU buffers [n_layers, size, n_kv_heads, head_dim]
+Layer 2 — ``ReqToTokenPool``: index table [req_idx, pos] → physical token slot
+Layer 3 — ``KVCache``:       pure dataclass passed to the model for direct buffer access
+
+These classes have no knowledge of tasks, allocation policies, or scheduling.
+They are the "dumb" physical storage layer.
+"""
+
+import threading
+from dataclasses import dataclass
+from typing import List, Optional
+
+import torch
+from torch import Tensor
+
+
+class ReqToTokenPool:
+    """Maps [req_idx, pos] → physical token slot in KV storage.
+
+    Each row is one request; each column is a sequence position.  The value
+    at [req_idx, pos] is the flat index into the KV storage buffers.
+    """
+
+    def __init__(self, size: int, max_context_len: int, device: torch.device):
+        self.size = size
+        self.max_context_len = max_context_len
+        self.req_to_token = torch.zeros(
+            (size, max_context_len), dtype=torch.int32, device=device
+        )
+        self.free_slots = list(range(size))
+        self._lock = threading.Lock()
+
+    def alloc(self, num_reqs: int) -> Optional[List[int]]:
+        with self._lock:
+            if num_reqs > len(self.free_slots):
+                return None
+            slots = self.free_slots[:num_reqs]
+            self.free_slots = self.free_slots[num_reqs:]
+            return slots
+
+    def free(self, req_indices: List[int]):
+        with self._lock:
+            self.free_slots.extend(req_indices)
+
+    def write(self, indices, values):
+        self.req_to_token[indices] = values
+
+
+class KVStorage:
+    """Token-level KV cache storage.
+
+    Buffers: ``[n_layers, size, n_kv_heads, head_dim]``.  Each token occupies
+    one slot indexed by ``ReqToTokenPool``.
+    """
+
+    def __init__(
+        self,
+        size: int,
+        n_layers: int,
+        n_kv_heads: int,
+        head_dim: int,
+        device: torch.device,
+        dtype: torch.dtype,
+    ):
+        self.size = size
+        self.k_buffer = torch.empty(
+            (n_layers, size, n_kv_heads, head_dim), device=device, dtype=dtype
+        )
+        self.v_buffer = torch.empty(
+            (n_layers, size, n_kv_heads, head_dim), device=device, dtype=dtype
+        )
+
+
+@dataclass
+class KVCache:
+    """Pure data struct passed to model for KV cache I/O.
+
+    The attention layer does raw buffer indexing — no methods, no abstraction.
+    """
+
+    k_buffer: Tensor
+    v_buffer: Tensor
+    req_to_token: Tensor
+    req_pool_indices: Tensor
+    seq_lens: Tensor
+    out_cache_loc: Tensor
+    max_len: int = 0
+    kv_indptr: Optional[Tensor] = None
+    qo_indptr: Optional[Tensor] = None
+    q_tile_to_batch: Optional[Tensor] = None
+    q_tile_to_index: Optional[Tensor] = None
+    decode_o_part: Optional[Tensor] = None
+    decode_ml_part: Optional[Tensor] = None
+    decode_out: Optional[Tensor] = None

astrai/inference/cache/pool.py

@@ -0,0 +1,382 @@
+"""KV cache orchestration: PagePool + TaskCacheManager.
+
+PagePool owns the physical buffers (``KVStorage`` + ``ReqToTokenPool``)
+and wires them to an allocation strategy.  It assembles the ``KVCache``
+dataclass passed to the model forward.
+
+TaskCacheManager owns the ``task_id`` → ``TaskCacheState`` mapping and
+delegates physical slot allocation to the strategy, and KV bind to the pool.
+
+See ``cache_buffer.py`` for the raw buffer primitives and ``cache_strategy.py``
+for the allocation policies.
+"""
+
+from dataclasses import dataclass
+from typing import Dict, List, Optional
+
+import torch
+
+from astrai.inference.cache.buffer import KVCache, KVStorage, ReqToTokenPool
+from astrai.inference.cache.strategy import (
+    AllocationStrategy,
+    Allocator,
+    ContiguousStrategy,
+    PagedStrategy,
+    RadixCache,
+    TaskCacheState,
+)
+from astrai.inference.workspace import Q_TILE_ROWS, InferenceWorkspace
+
+# Re-export everything so existing ``from astrai.inference.cache import ...``
+# continues to work unchanged after the file split.
+__all__ = [
+    "KVCache",
+    "KVStorage",
+    "ReqToTokenPool",
+    "Allocator",
+    "RadixCache",
+    "AllocationStrategy",
+    "ContiguousStrategy",
+    "PagedStrategy",
+    "PagePool",
+    "TaskCacheManager",
+    "TaskCacheState",
+    "page_hash",
+]
+
+# ---- helpers ----
+
+
+def page_hash(
+    token_ids: List[int], page_idx: int, page_size: int, parent_hash: int = 0
+) -> int:
+    start = page_idx * page_size
+    end = min(start + page_size, len(token_ids))
+    h = parent_hash
+    for i in range(start, end):
+        h = (h * 31 + token_ids[i]) & 0xFFFFFFFFFFFFFFFF
+    return h
+
+
+def _is_steady_increment(
+    prev_sig: Optional[tuple],
+    prev_vals: Optional[List[int]],
+    cur_sig: tuple,
+    cur_vals: List[int],
+) -> bool:
+    return (
+        prev_sig is not None
+        and prev_vals is not None
+        and prev_sig == cur_sig
+        and len(prev_vals) == len(cur_vals)
+        and all(c == p + 1 for c, p in zip(cur_vals, prev_vals))
+    )
+
+
+# ---- task-scoped bind state ----
+@dataclass
+class _BindState:
+    """Cached bind metadata for steady-state decode increment detection."""
+
+    sig: tuple
+    seq_lens: List[int]
+
+
+# ---- pool + manager ----
+
+
+class PagePool:
+    """Physical KV cache: buffers + req-to-token table + allocation strategy + bind.
+
+    Does not know about tasks — task lifecycle is managed by
+    :class:`TaskCacheManager`, which holds a reference to this pool.
+    """
+
+    def __init__(
+        self,
+        n_layers: int,
+        n_kv_heads: int,
+        head_dim: int,
+        max_batch_size: int,
+        max_seq_len: int,
+        device: torch.device,
+        dtype: torch.dtype,
+        page_size: int = 1,
+        n_tokens: Optional[int] = None,
+    ):
+        self.page_size = page_size
+        self.max_batch_size = max_batch_size
+        self.max_seq_len = max_seq_len
+        self.device = device
+        self.dtype = dtype
+        self.n_layers = n_layers
+        self.n_kv_heads = n_kv_heads
+        self.head_dim = head_dim
+
+        self.contiguous = n_tokens is None
+        self.n_tokens = max_batch_size * max_seq_len if self.contiguous else n_tokens
+        if self.n_tokens > torch.iinfo(torch.int32).max:
+            raise ValueError("KV cache token count exceeds the int32 slot index limit")
+
+        self._storage = KVStorage(
+            self.n_tokens, n_layers, n_kv_heads, head_dim, device, dtype
+        )
+        self._req_pool = ReqToTokenPool(max_batch_size, max_seq_len, device)
+
+        if self.contiguous:
+            for i in range(max_batch_size):
+                self._req_pool.req_to_token[i] = torch.arange(
+                    i * max_seq_len,
+                    (i + 1) * max_seq_len,
+                    dtype=torch.int32,
+                    device=device,
+                )
+            self._strategy: AllocationStrategy = ContiguousStrategy()
+        else:
+            n_pages = self.n_tokens // page_size
+            alloc = Allocator(n_pages)
+            prefix = RadixCache(page_size) if page_size > 1 else None
+            if prefix is not None:
+                alloc.on_evict = prefix.evict
+            self._strategy = PagedStrategy(
+                alloc, prefix, page_size, self._req_pool, device
+            )
+
+    @property
+    def strategy(self) -> AllocationStrategy:
+        return self._strategy
+
+    @property
+    def req_pool(self) -> ReqToTokenPool:
+        return self._req_pool
+
+    def bind_tasks(
+        self,
+        req_indices: List[int],
+        seq_lens: List[int],
+        workspace: InferenceWorkspace,
+        device: Optional[torch.device] = None,
+        start_pos: Optional[int] = None,
+        incremental: bool = False,
+    ) -> KVCache:
+        """Assemble the ``KVCache`` metadata for a batch of tasks.
+
+        Args:
+            req_indices: request slot indices (from ``ReqToTokenPool``).
+            seq_lens:    current sequence length per task.
+            workspace:   pre-allocated fixed-shape buffers (CUDA-graph safe).
+            start_pos:   if set, produce **prefill** cache (full q_len range).
+                         If ``None``, produce **decode** cache (last position).
+            incremental: if ``True``, reuse workspace state from previous step
+                         by incrementing counters in-place (decode hot path).
+
+        Returns:
+            ``KVCache`` dataclass with the correct output shapes for the
+            attention backend (prefill: ``[B, q_len]``, decode: ``[B, 1]``).
+        """
+        if device is None:
+            device = workspace.device
+        b = len(req_indices)
+
+        rpi_buf = workspace.req_pool_indices
+        sl_buf = workspace.seq_lens
+        kvp_buf = workspace.kv_indptr
+        inc_buf = workspace.inc
+        ocl_buf = workspace.out_cache_loc
+
+        if incremental:
+            sl_buf[:b] += 1
+            kvp_buf[: b + 1] += inc_buf[: b + 1]
+        else:
+            rpi_buf[:b].copy_(
+                torch.tensor(req_indices, dtype=torch.int32, device=device)
+            )
+            sl_buf[:b].copy_(torch.tensor(seq_lens, dtype=torch.long, device=device))
+            kvp_buf[: b + 1].zero_()
+            kvp_buf[1 : b + 1] = sl_buf[:b].cumsum(0).to(torch.int32)
+
+        req_pool_indices = rpi_buf[:b]
+        seq_lens_t = sl_buf[:b]
+        kv_indptr = kvp_buf[: b + 1]
+
+        if start_pos is not None:
+            # Packed prefill concatenates each request's query tokens.
+            q_lens = [seq_len - start_pos for seq_len in seq_lens]
+            if any(q_len <= 0 for q_len in q_lens):
+                raise ValueError("prefill sequence lengths must exceed start_pos")
+            out_cache_loc = torch.cat(
+                [
+                    self._req_pool.req_to_token[
+                        req_pool_indices[i], start_pos : seq_lens[i]
+                    ]
+                    for i in range(b)
+                ]
+            )
+            workspace.qo_indptr[: b + 1].zero_()
+            workspace.qo_indptr[1 : b + 1].copy_(
+                torch.tensor(q_lens, dtype=torch.int32, device=device).cumsum(0)
+            )
+            qo_indptr = workspace.qo_indptr[: b + 1]
+            tile_batches = []
+            tile_indices = []
+            for batch, q_len in enumerate(q_lens):
+                n_tiles = (q_len + Q_TILE_ROWS - 1) // Q_TILE_ROWS
+                tile_batches.extend([batch] * n_tiles)
+                tile_indices.extend(range(n_tiles))
+            n_tiles = len(tile_batches)
+            workspace.q_tile_to_batch[:n_tiles].copy_(
+                torch.tensor(tile_batches, dtype=torch.int32, device=device)
+            )
+            workspace.q_tile_to_index[:n_tiles].copy_(
+                torch.tensor(tile_indices, dtype=torch.int32, device=device)
+            )
+            q_tile_to_batch = workspace.q_tile_to_batch[:n_tiles]
+            q_tile_to_index = workspace.q_tile_to_index[:n_tiles]
+            decode_o_part = decode_ml_part = decode_out = None
+        else:
+            # ---- decode: out_cache_loc is a single column (last position) ----
+            write_pos = seq_lens_t - 1
+            loc = self._req_pool.req_to_token[req_pool_indices, write_pos].unsqueeze(-1)
+            ocl_buf[:b].copy_(loc)
+            out_cache_loc = ocl_buf[:b].reshape(-1)
+            workspace.qo_indptr[: b + 1].copy_(inc_buf[: b + 1])
+            qo_indptr = workspace.qo_indptr[: b + 1]
+            q_tile_to_batch = q_tile_to_index = None
+            decode_o_part = getattr(workspace, "decode_o_part", None)
+            decode_ml_part = getattr(workspace, "decode_ml_part", None)
+            decode_out = getattr(workspace, "decode_out", None)
+
+        return KVCache(
+            k_buffer=self._storage.k_buffer,
+            v_buffer=self._storage.v_buffer,
+            req_to_token=self._req_pool.req_to_token,
+            req_pool_indices=req_pool_indices,
+            seq_lens=seq_lens_t,
+            out_cache_loc=out_cache_loc,
+            max_len=max(seq_lens),
+            kv_indptr=kv_indptr,
+            qo_indptr=qo_indptr,
+            q_tile_to_batch=q_tile_to_batch,
+            q_tile_to_index=q_tile_to_index,
+            decode_o_part=decode_o_part,
+            decode_ml_part=decode_ml_part,
+            decode_out=decode_out,
+        )
+
+
+class TaskCacheManager:
+    """Task ↔ KV slot lifecycle manager.
+
+    Sole owner of ``task_id → TaskCacheState``.  Delegates physical slot
+    allocation to the strategy (via ``pool.strategy``) and KV bind to
+    ``pool.bind_tasks()``.
+
+    Usage::
+
+        pool = PagePool(...)
+        mgr = TaskCacheManager(pool)
+        mgr.task_alloc("req_1", [101, 202, 303])
+        ...
+        kv = mgr.bind(["req_1"], workspace)
+    """
+
+    def __init__(self, pool: PagePool):
+        self._pool = pool
+        self._strategy = pool.strategy
+        self._req_pool = pool.req_pool
+        self._max_seq_len = pool.max_seq_len
+        self._states: Dict[str, TaskCacheState] = {}
+        self._bind_state: Optional[_BindState] = None
+        self._bind_was_steady = False
+
+    # -- public task lifecycle --
+
+    def task_alloc(self, task_id: str, prompt_ids: List[int]) -> bool:
+        self._bind_state = None
+        req_slots = self._req_pool.alloc(1)
+        if req_slots is None:
+            return False
+        state = TaskCacheState(req_idx=req_slots[0])
+        self._states[task_id] = state
+        if not self._strategy.alloc(state, prompt_ids):
+            self._rollback(state, task_id)
+            return False
+        self._strategy.write_indices(state, prompt_ids)
+        state.length = len(prompt_ids)
+        return True
+
+    def task_free(self, task_id: str):
+        self._bind_state = None
+        state = self._states.pop(task_id, None)
+        if state is None:
+            return
+        self._strategy.free(state)
+        self._req_pool.free([state.req_idx])
+
+    def task_extend(self, task_id: str, pos: int) -> bool:
+        state = self._states.get(task_id)
+        if state is None or pos >= self._max_seq_len:
+            return False
+        if not self._strategy.extend(state, pos):
+            return False
+        state.length = pos + 1
+        return True
+
+    def task_cached(self, task_id: str) -> int:
+        state = self._states.get(task_id)
+        return state.cached if state is not None else 0
+
+    def task_record_hashes(
+        self, task_id: str, prompt_ids: List[int], start_logical_page: int = 0
+    ):
+        state = self._states.get(task_id)
+        if state is not None:
+            self._strategy.record_hashes(state, prompt_ids, start_logical_page)
+
+    @staticmethod
+    def task_cacheable_ids(task_id: str, prompt_ids: List[int], output_ids: List[int]):
+        return list(prompt_ids) + list(output_ids[:-1])
+
+    # -- bind (assemble KVCache for the model forward) --
+
+    def bind(
+        self,
+        task_ids: List[str],
+        workspace: InferenceWorkspace,
+        device: Optional[torch.device] = None,
+        start_pos: Optional[int] = None,
+    ) -> KVCache:
+        """Build ``KVCache`` for an ordered list of task IDs."""
+        states = [self._states[tid] for tid in task_ids]
+        req_indices = [s.req_idx for s in states]
+        seq_lens = [s.length for s in states]
+        sig = tuple(req_indices)
+
+        prev = self._bind_state
+        incremental = (
+            start_pos is None
+            and prev is not None
+            and _is_steady_increment(prev.sig, prev.seq_lens, sig, seq_lens)
+        )
+        self._bind_state = _BindState(sig, list(seq_lens))
+        self._bind_was_steady = incremental
+
+        return self._pool.bind_tasks(
+            req_indices,
+            seq_lens,
+            workspace,
+            device=device,
+            start_pos=start_pos,
+            incremental=incremental,
+        )
+
+    @property
+    def bind_was_steady(self) -> bool:
+        return self._bind_was_steady
+
+    # -- internals --
+
+    def _rollback(self, state: TaskCacheState, task_id: str):
+        self._strategy.free(state)
+        self._req_pool.free([state.req_idx])
+        self._states.pop(task_id, None)

astrai/inference/cache/strategy.py

@@ -0,0 +1,318 @@
+"""KV cache allocation layer.
+
+Encapsulates the physical slot allocation policy, isolated from GPU buffers
+and task lifecycle management.
+
+- ``TaskCacheState``: data contract between strategy and manager (per-task slot state)
+- ``Allocator``:       bitmask-based page allocator with LRU eviction
+- ``RadixCache``:      page-granular prefix index (exact token match)
+- ``AllocationStrategy``: ABC for physical slot allocation
+- ``ContiguousStrategy``: statically partitioned, no dynamic allocation
+- ``PagedStrategy``:    dynamic paged allocation from a shared pool
+"""
+
+import threading
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+from typing import Callable, Dict, List, Optional, OrderedDict
+
+from astrai.inference.cache.buffer import ReqToTokenPool
+
+# ---- data contract: per-task slot state ----
+
+
+@dataclass
+class TaskCacheState:
+    """Per-task cache allocation state.
+
+    Co-locates all task-owned cache metadata so the alloc/free/extend
+    lifecycle is atomic.  Owned by ``TaskCacheManager``, consumed by
+    every ``AllocationStrategy`` method.
+    """
+
+    req_idx: int
+    length: int = 0
+    cached: int = 0
+    pages: List[int] = field(default_factory=list)
+
+
+# ---- allocation primitives ----
+
+
+class Allocator:
+    """Bitmask-based page allocator with ref-counting and LRU eviction."""
+
+    def __init__(self, n_pages: int):
+        self._free_mask = (1 << n_pages) - 1
+        self._refs: List[int] = [0] * n_pages
+        self._lru: OrderedDict[int, None] = OrderedDict()
+        self.on_evict: Optional[Callable[[int], None]] = None
+        self._lock = threading.Lock()
+
+    def alloc(self) -> int:
+        with self._lock:
+            if self._free_mask:
+                lsb = self._free_mask & -self._free_mask
+                idx = lsb.bit_length() - 1
+                self._free_mask ^= lsb
+                self._refs[idx] = 1
+                return idx
+            if self._lru:
+                idx, _ = self._lru.popitem(last=False)
+                if self.on_evict:
+                    self.on_evict(idx)
+                self._refs[idx] = 1
+                self._free_mask &= ~(1 << idx)
+                return idx
+            return -1
+
+    def free(self, idx: int, keep_cached: bool = False):
+        with self._lock:
+            self._refs[idx] -= 1
+            if self._refs[idx] == 0:
+                if keep_cached:
+                    self._lru[idx] = None
+                else:
+                    self._free_mask |= 1 << idx
+
+    def inc_ref(self, idx: int):
+        with self._lock:
+            self._refs[idx] += 1
+            self._lru.pop(idx, None)
+
+    def ref_count(self, idx: int) -> int:
+        with self._lock:
+            return self._refs[idx]
+
+    def touch(self, idx: int):
+        with self._lock:
+            if idx in self._lru:
+                self._lru.move_to_end(idx)
+
+
+class RadixNode:
+    """A page-aligned edge in the CPU-side prefix radix trie."""
+
+    __slots__ = ("parent", "children", "page_idx", "tokens", "lock_ref")
+
+    def __init__(self, parent=None, tokens=(), page_idx=None):
+        self.parent = parent
+        self.children: Dict[tuple, "RadixNode"] = {}
+        self.page_idx = page_idx
+        self.tokens = tuple(tokens)
+        self.lock_ref = 0
+
+
+class RadixCache:
+    """Page-granular radix prefix index with exact token matching."""
+
+    def __init__(self, page_size: int):
+        self._page_size = page_size
+        self._root = RadixNode()
+        self._page_to_node: Dict[int, RadixNode] = {}
+        self._lock = threading.Lock()
+
+    def evict(self, idx: int):
+        with self._lock:
+            node = self._page_to_node.pop(idx, None)
+            if node is None:
+                return
+            node.page_idx = None
+            parent = node.parent
+            if parent is not None:
+                parent.children.pop(node.tokens, None)
+
+    def has_page(self, idx: int) -> bool:
+        with self._lock:
+            return idx in self._page_to_node
+
+    def lookup(self, token_ids: List[int]) -> List[int]:
+        with self._lock:
+            full_pages = len(token_ids) // self._page_size
+            hits: List[int] = []
+            node = self._root
+            for i in range(full_pages):
+                start = i * self._page_size
+                page_tokens = tuple(token_ids[start : start + self._page_size])
+                child = node.children.get(page_tokens)
+                if child is None or child.page_idx is None:
+                    break
+                hits.append(child.page_idx)
+                node = child
+            return hits
+
+    def record(self, page_idx: int, token_ids: List[int], logical_page_idx: int):
+        with self._lock:
+            full_pages = len(token_ids) // self._page_size
+            if logical_page_idx >= full_pages:
+                return
+            old = self._page_to_node.pop(page_idx, None)
+            if old is not None and old.parent is not None:
+                old.parent.children.pop(old.tokens, None)
+
+            node = self._root
+            for i in range(logical_page_idx + 1):
+                start = i * self._page_size
+                page_tokens = tuple(token_ids[start : start + self._page_size])
+                child = node.children.get(page_tokens)
+                if child is None:
+                    child = RadixNode(node, page_tokens)
+                    node.children[page_tokens] = child
+                node = child
+            if node.page_idx is not None and node.page_idx != page_idx:
+                replaced = node.page_idx
+                self._page_to_node.pop(replaced, None)
+            node.page_idx = page_idx
+            self._page_to_node[page_idx] = node
+
+    def release(self, pages: List[int]) -> None:
+        with self._lock:
+            for page_idx in pages:
+                node = self._page_to_node.get(page_idx)
+                if node is not None and node.lock_ref:
+                    node.lock_ref -= 1
+
+
+class AllocationStrategy(ABC):
+    """Physical slot allocation policy.
+
+    Subclasses implement the actual allocation semantics.  This ABC declares
+    the contract; there are no default implementations.
+    """
+
+    @abstractmethod
+    def alloc(self, state: TaskCacheState, prompt_ids: List[int]) -> bool: ...
+
+    @abstractmethod
+    def free(self, state: TaskCacheState) -> None: ...
+
+    @abstractmethod
+    def extend(self, state: TaskCacheState, pos: int) -> bool: ...
+
+    @abstractmethod
+    def write_indices(self, state: TaskCacheState, prompt_ids: List[int]) -> None: ...
+
+    @abstractmethod
+    def record_hashes(
+        self,
+        state: TaskCacheState,
+        prompt_ids: List[int],
+        start: int,
+    ) -> None: ...
+
+
+class ContiguousStrategy(AllocationStrategy):
+    """Static contiguous allocation: slots are pre-assigned at pool init.
+
+    No dynamic allocation or prefix caching.  All operations are no-ops
+    because ``ReqToTokenPool`` is pre-filled with contiguous ranges.
+    """
+
+    def alloc(self, state: TaskCacheState, prompt_ids: List[int]) -> bool:
+        return True
+
+    def free(self, state: TaskCacheState) -> None:
+        pass
+
+    def extend(self, state: TaskCacheState, pos: int) -> bool:
+        return True
+
+    def write_indices(self, state: TaskCacheState, prompt_ids: List[int]) -> None:
+        pass
+
+    def record_hashes(
+        self,
+        state: TaskCacheState,
+        prompt_ids: List[int],
+        start: int,
+    ) -> None:
+        pass
+
+
+class PagedStrategy(AllocationStrategy):
+    """Dynamic paged allocation from a shared bitmask pool.
+
+    ``page_size`` is a parameter, not a separate strategy: at ``page_size=1``
+    each allocated page *is* one token slot (``page * 1 + 0``), and prefix
+    caching is simply disabled (``prefix=None``).  The unified page formula
+    ``pages[page_idx] * page_size + offset`` holds for both.
+    """
+
+    def __init__(
+        self,
+        alloc: Allocator,
+        prefix: Optional[RadixCache],
+        page_size: int,
+        req_pool: ReqToTokenPool,
+        device,
+    ):
+        self._alloc = alloc
+        self._prefix = prefix
+        self._page_size = page_size
+        self._req_pool = req_pool
+        self._device = device
+
+    def alloc(self, state: TaskCacheState, prompt_ids: List[int]) -> bool:
+        if self._prefix is not None:
+            hits = self._prefix.lookup(prompt_ids)
+            state.cached = len(hits) * self._page_size
+            for p in hits:
+                self._alloc.inc_ref(p)
+            state.pages = list(hits)
+
+        remaining = len(prompt_ids) - state.cached
+        if remaining <= 0:
+            return True
+        n_new = (remaining + self._page_size - 1) // self._page_size
+        for _ in range(n_new):
+            p = self._alloc.alloc()
+            if p < 0:
+                return False
+            state.pages.append(p)
+        return True
+
+    def free(self, state: TaskCacheState) -> None:
+        if self._prefix is not None:
+            for p in state.pages:
+                keep = self._prefix.has_page(p)
+                self._alloc.free(p, keep_cached=keep)
+                if not keep:
+                    self._prefix.evict(p)
+        else:
+            for p in state.pages:
+                self._alloc.free(p)
+
+    def extend(self, state: TaskCacheState, pos: int) -> bool:
+        page_idx = pos // self._page_size
+        if page_idx >= len(state.pages):
+            p = self._alloc.alloc()
+            if p < 0:
+                return False
+            state.pages.append(p)
+        offset = pos % self._page_size
+        self._req_pool.req_to_token[state.req_idx, pos] = (
+            state.pages[page_idx] * self._page_size + offset
+        )
+        return True
+
+    def write_indices(self, state: TaskCacheState, prompt_ids: List[int]) -> None:
+        total = len(prompt_ids)
+        for pos in range(total):
+            page_idx = pos // self._page_size
+            offset = pos % self._page_size
+            if page_idx < len(state.pages):
+                self._req_pool.req_to_token[state.req_idx, pos] = (
+                    state.pages[page_idx] * self._page_size + offset
+                )
+
+    def record_hashes(
+        self,
+        state: TaskCacheState,
+        prompt_ids: List[int],
+        start: int,
+    ) -> None:
+        if self._prefix is None:
+            return
+        full = len(prompt_ids) // self._page_size
+        for i in range(start, min(full, len(state.pages))):
+            self._prefix.record(state.pages[i], prompt_ids, i)

astrai/inference/core/__init__.py

@@ -1,40 +0,0 @@
-"""Inference core: cache, executor, scheduler, task management."""
-
-from astrai.inference.core.cache import (
-    Allocator,
-    CacheView,
-    ContiguousCache,
-    ContiguousCacheView,
-    KVCache,
-    PageCache,
-    PageCacheView,
-    PagePool,
-    PrefixCache,
-    Storage,
-    TaskTable,
-    page_hash,
-)
-from astrai.inference.core.executor import Executor
-from astrai.inference.core.scheduler import InferenceScheduler
-from astrai.inference.core.task import STOP, Task, TaskManager, TaskStatus
-
-__all__ = [
-    "Allocator",
-    "CacheView",
-    "KVCache",
-    "ContiguousCache",
-    "ContiguousCacheView",
-    "PageCache",
-    "PageCacheView",
-    "PagePool",
-    "PrefixCache",
-    "Storage",
-    "TaskTable",
-    "page_hash",
-    "Executor",
-    "InferenceScheduler",
-    "STOP",
-    "Task",
-    "TaskManager",
-    "TaskStatus",
-]

astrai/inference/core/cache.py

@@ -1,499 +0,0 @@
-import threading
-from abc import ABC, abstractmethod
-from collections import OrderedDict
-from typing import Callable, Dict, List, Optional, Tuple
-
-import torch
-from torch import Tensor
-
-
-def page_hash(token_ids: List[int], page_idx: int, page_size: int) -> int:
-    start = page_idx * page_size
-    end = min(start + page_size, len(token_ids))
-    h = 0
-    for i in range(start, end):
-        h = (h * 31 + token_ids[i]) & 0xFFFFFFFFFFFFFFFF
-    return h
-
-
-class Allocator:
-    """Bitmask-based page allocator with ref-counting and LRU eviction."""
-
-    def __init__(self, n_pages: int):
-        self._free_mask = (1 << n_pages) - 1
-        self._refs: List[int] = [0] * n_pages
-        self._lru: OrderedDict[int, None] = OrderedDict()
-        self.on_evict: Optional[Callable[[int], None]] = None
-        self._lock = threading.Lock()
-
-    def alloc(self) -> int:
-        with self._lock:
-            if self._free_mask:
-                lsb = self._free_mask & -self._free_mask
-                idx = lsb.bit_length() - 1
-                self._free_mask ^= lsb
-                self._refs[idx] = 1
-                return idx
-            if self._lru:
-                idx, _ = self._lru.popitem(last=False)
-                if self.on_evict:
-                    self.on_evict(idx)
-                self._refs[idx] = 1
-                self._free_mask &= ~(1 << idx)
-                return idx
-            return -1
-
-    def free(self, idx: int, keep_cached: bool = False):
-        with self._lock:
-            self._refs[idx] -= 1
-            if self._refs[idx] == 0:
-                if keep_cached:
-                    self._lru[idx] = None
-                else:
-                    self._free_mask |= 1 << idx
-
-    def inc_ref(self, idx: int):
-        with self._lock:
-            self._refs[idx] += 1
-            self._lru.pop(idx, None)
-
-    def ref_count(self, idx: int) -> int:
-        with self._lock:
-            return self._refs[idx]
-
-    def touch(self, idx: int):
-        with self._lock:
-            if idx in self._lru:
-                self._lru.move_to_end(idx)
-
-
-class PrefixCache:
-    """Hash-based prefix matching: maps page hashes to physical page indices."""
-
-    def __init__(self, page_size: int):
-        self._page_size = page_size
-        self._page_to_hash: Dict[int, int] = {}
-        self._hash_to_page: Dict[int, int] = {}
-        self._lock = threading.Lock()
-
-    def evict(self, idx: int):
-        with self._lock:
-            h = self._page_to_hash.pop(idx, None)
-            if h is not None:
-                self._hash_to_page.pop(h, None)
-
-    def has_page(self, idx: int) -> bool:
-        with self._lock:
-            return idx in self._page_to_hash
-
-    def lookup(self, token_ids: List[int]) -> List[int]:
-        with self._lock:
-            full_pages = len(token_ids) // self._page_size
-            hits: List[int] = []
-            for i in range(full_pages):
-                h = page_hash(token_ids, i, self._page_size)
-                p = self._hash_to_page.get(h)
-                if p is None:
-                    break
-                hits.append(p)
-            return hits
-
-    def record(self, page_idx: int, token_ids: List[int], logical_page_idx: int):
-        with self._lock:
-            h = page_hash(token_ids, logical_page_idx, self._page_size)
-            old_h = self._page_to_hash.pop(page_idx, None)
-            if old_h is not None:
-                self._hash_to_page.pop(old_h, None)
-            self._page_to_hash[page_idx] = h
-            self._hash_to_page[h] = page_idx
-
-
-class PagePool:
-    """Orchestrates allocator (page management) and PrefixCache (content addressing)."""
-
-    def __init__(self, allocator: Allocator, prefix: PrefixCache):
-        self._alloc = allocator
-        self._prefix = prefix
-        self._alloc.on_evict = prefix.evict
-
-    @property
-    def allocator(self) -> Allocator:
-        return self._alloc
-
-    @property
-    def prefix(self) -> PrefixCache:
-        return self._prefix
-
-    def alloc(self) -> int:
-        return self._alloc.alloc()
-
-    def free(self, idx: int):
-        keep = self._prefix.has_page(idx)
-        self._alloc.free(idx, keep_cached=keep)
-        if not keep:
-            self._prefix.evict(idx)
-
-    def inc_ref(self, idx: int):
-        self._alloc.inc_ref(idx)
-
-    def lookup(self, token_ids: List[int]) -> List[int]:
-        hits = self._prefix.lookup(token_ids)
-        for p in hits:
-            self._alloc.touch(p)
-        return hits
-
-    def record(self, page_idx: int, token_ids: List[int], logical_page_idx: int):
-        self._prefix.record(page_idx, token_ids, logical_page_idx)
-
-
-class TaskTable:
-    """Maps task_ids to page tables and cached token counts."""
-
-    def __init__(self, page_size: int):
-        self._page_size = page_size
-        self._pages: Dict[str, List[int]] = {}
-        self._cached: Dict[str, int] = {}
-        self._lock = threading.Lock()
-
-    def set(self, task_id: str, page_table: List[int], cached: int):
-        with self._lock:
-            self._pages[task_id] = page_table
-            self._cached[task_id] = cached
-
-    def get(self, task_id: str) -> List[int]:
-        with self._lock:
-            return self._pages.get(task_id, [])
-
-    def get_cached(self, task_id: str) -> int:
-        with self._lock:
-            return self._cached.get(task_id, 0)
-
-    def pop(self, task_id: str) -> Tuple[List[int], int]:
-        with self._lock:
-            pages = self._pages.pop(task_id, [])
-            cached = self._cached.pop(task_id, 0)
-            return pages, cached
-
-    def get_ref(self, task_id: str) -> List[int]:
-        with self._lock:
-            return self._pages.setdefault(task_id, [])
-
-    def table_tensor(self, task_ids: List[str], device: torch.device) -> Tensor:
-        with self._lock:
-            states = [self._pages.get(tid, []) for tid in task_ids]
-            max_pages = max((len(s) for s in states), default=0)
-            rows = [s + [-1] * (max_pages - len(s)) for s in states]
-            return torch.tensor(rows, dtype=torch.long, device=device)
-
-
-class Storage:
-    """KV-cache tensor storage with paged write/gather."""
-
-    def __init__(
-        self,
-        n_layers: int,
-        n_pages: int,
-        page_size: int,
-        n_kv_heads: int,
-        head_dim: int,
-        device: torch.device,
-        dtype: torch.dtype,
-    ):
-        self.page_size = page_size
-        self.k_cache = torch.empty(
-            (n_layers, n_pages, page_size, n_kv_heads, head_dim),
-            device=device,
-            dtype=dtype,
-        )
-        self.v_cache = torch.empty(
-            (n_layers, n_pages, page_size, n_kv_heads, head_dim),
-            device=device,
-            dtype=dtype,
-        )
-
-    def write(
-        self,
-        layer_id: int,
-        page_table: Tensor,
-        start_pos: int,
-        k: Tensor,
-        v: Tensor,
-    ):
-        seq_len = k.size(1)
-        if seq_len == 0:
-            return
-        page_size = self.page_size
-        written = 0
-        first_page = start_pos // page_size
-        last_page = (start_pos + seq_len - 1) // page_size
-        for pi in range(first_page, last_page + 1):
-            phys_pages = page_table[:, pi]
-            page_start = pi * page_size
-            write_start = max(page_start, start_pos)
-            write_end = min(page_start + page_size, start_pos + seq_len)
-            offset = write_start - page_start
-            chunk = write_end - write_start
-            valid = phys_pages >= 0
-            if not valid.all():
-                if valid.any():
-                    valid_pages = phys_pages[valid]
-                    self.k_cache[layer_id, valid_pages, offset : offset + chunk] = k[
-                        valid, written : written + chunk
-                    ]
-                    self.v_cache[layer_id, valid_pages, offset : offset + chunk] = v[
-                        valid, written : written + chunk
-                    ]
-                written += chunk
-                continue
-            self.k_cache[layer_id, phys_pages, offset : offset + chunk] = k[
-                :, written : written + chunk
-            ]
-            self.v_cache[layer_id, phys_pages, offset : offset + chunk] = v[
-                :, written : written + chunk
-            ]
-            written += chunk
-
-    def gather(
-        self, layer_id: int, page_table: Tensor, total_len: int
-    ) -> Tuple[Tensor, Tensor]:
-        safe = page_table.clamp(min=0)
-        k = self.k_cache[layer_id, safe]
-        v = self.v_cache[layer_id, safe]
-        k = k.flatten(1, 2)
-        v = v.flatten(1, 2)
-        if (page_table < 0).any():
-            invalid = (
-                (page_table < 0)
-                .unsqueeze(-1)
-                .expand(-1, -1, self.page_size)
-                .flatten(1, 2)
-            )
-            invalid = invalid[:, :, None, None].expand_as(k)
-            k = k.masked_fill(invalid, 0.0)
-            v = v.masked_fill(invalid, 0.0)
-        k = k[:, :total_len]
-        v = v[:, :total_len]
-        return k, v
-
-
-class CacheView(ABC):
-    """Abstract view passed to attention layers for KV-cache I/O."""
-
-    @abstractmethod
-    def write(self, layer_id: int, k: Tensor, v: Tensor): ...
-
-    @abstractmethod
-    def gather(self, layer_id: int) -> Tuple[Tensor, Tensor]: ...
-
-
-class KVCache(ABC):
-    """Abstract KV-cache facade for scheduler/executor."""
-
-    @abstractmethod
-    def task_alloc(self, task_id: str, prompt_ids: List[int]) -> bool: ...
-
-    @abstractmethod
-    def task_free(self, task_id: str): ...
-
-    @abstractmethod
-    def task_extend(self, task_id: str, pos: int) -> bool: ...
-
-    @abstractmethod
-    def bind_tasks(
-        self, task_ids: List[str], total_len: int, device: torch.device
-    ) -> CacheView: ...
-
-    def task_cached(self, task_id: str) -> int:
-        return 0
-
-    def task_record_hashes(
-        self, task_id: str, prompt_ids: List[int], start_logical_page: int = 0
-    ): ...
-
-
-class PageCacheView(CacheView):
-    """Bundles Storage + page_table + total_len for attention layers."""
-
-    def __init__(self, storage: Storage, page_table: Tensor, total_len: int = 0):
-        self._storage = storage
-        self._page_table = page_table
-        self._total_len = total_len
-
-    def write(self, layer_id: int, k: Tensor, v: Tensor):
-        start_pos = self._total_len - k.size(1)
-        self._storage.write(layer_id, self._page_table, start_pos, k, v)
-
-    def gather(self, layer_id: int) -> Tuple[Tensor, Tensor]:
-        return self._storage.gather(layer_id, self._page_table, self._total_len)
-
-
-class PageCache(KVCache):
-    """Paged KV-cache with prefix sharing."""
-
-    def __init__(
-        self,
-        n_layers: int,
-        n_pages: int,
-        page_size: int,
-        n_kv_heads: int,
-        head_dim: int,
-        device: torch.device,
-        dtype: torch.dtype,
-    ):
-        self.page_size = page_size
-        self._pool = PagePool(Allocator(n_pages), PrefixCache(page_size))
-        self._table = TaskTable(page_size)
-        self._storage = Storage(
-            n_layers, n_pages, page_size, n_kv_heads, head_dim, device, dtype
-        )
-
-    def task_alloc(self, task_id: str, prompt_ids: List[int]) -> bool:
-        hits = self._pool.lookup(prompt_ids)
-        cached = len(hits) * self.page_size
-        for p in hits:
-            self._pool.inc_ref(p)
-
-        remaining = len(prompt_ids) - cached
-        n_new = (
-            (remaining + self.page_size - 1) // self.page_size if remaining > 0 else 0
-        )
-        new_pages: List[int] = []
-        if n_new > 0:
-            for _ in range(n_new):
-                p = self._pool.alloc()
-                if p < 0:
-                    for hp in hits:
-                        self._pool.free(hp)
-                    for np in new_pages:
-                        self._pool.free(np)
-                    return False
-                new_pages.append(p)
-
-        self._table.set(task_id, hits + new_pages, cached)
-        return True
-
-    def task_free(self, task_id: str):
-        page_table, _ = self._table.pop(task_id)
-        for idx in page_table:
-            self._pool.free(idx)
-
-    def task_extend(self, task_id: str, pos: int) -> bool:
-        page_table = self._table.get(task_id)
-        needed = (pos + 1 + self.page_size - 1) // self.page_size
-        while len(page_table) < needed:
-            p = self._pool.alloc()
-            if p < 0:
-                return False
-            page_table.append(p)
-        return True
-
-    def task_cached(self, task_id: str) -> int:
-        return self._table.get_cached(task_id)
-
-    def task_record_hashes(
-        self, task_id: str, prompt_ids: List[int], start_logical_page: int = 0
-    ):
-        page_table = self._table.get(task_id)
-        full_pages = len(prompt_ids) // self.page_size
-        for i in range(start_logical_page, full_pages):
-            self._pool.record(page_table[i], prompt_ids, i)
-
-    def bind_tasks(
-        self, task_ids: List[str], total_len: int, device: torch.device
-    ) -> PageCacheView:
-        page_table = self._table.table_tensor(task_ids, device)
-        return PageCacheView(self._storage, page_table, total_len)
-
-
-class ContiguousCacheView(CacheView):
-    """Contiguous KV-cache view for attention layers."""
-
-    def __init__(
-        self, cache: "ContiguousCache", batch_indices: Tensor, total_len: int = 0
-    ):
-        self._cache = cache
-        self._batch_indices = batch_indices
-        self._total_len = total_len
-
-    def write(self, layer_id: int, k: Tensor, v: Tensor):
-        seq_len = k.size(1)
-        start_pos = self._total_len - seq_len
-        indices = self._batch_indices
-        self._cache.k[layer_id, indices, start_pos : start_pos + seq_len] = k
-        self._cache.v[layer_id, indices, start_pos : start_pos + seq_len] = v
-        new_len = start_pos + seq_len
-        for s in indices.tolist():
-            cur = self._cache._slot_len.get(s, 0)
-            if new_len > cur:
-                self._cache._slot_len[s] = new_len
-
-    def gather(self, layer_id: int) -> Tuple[Tensor, Tensor]:
-        max_len = max(
-            self._cache._slot_len.get(int(s), 0) for s in self._batch_indices.tolist()
-        )
-        indices = self._batch_indices
-        k = self._cache.k[layer_id, indices, :max_len]
-        v = self._cache.v[layer_id, indices, :max_len]
-        return k, v
-
-
-class ContiguousCache(KVCache):
-    """Contiguous per-slot KV cache (default implementation)."""
-
-    def __init__(
-        self,
-        n_layers: int,
-        max_batch_size: int,
-        max_seq_len: int,
-        n_kv_heads: int,
-        head_dim: int,
-        device: torch.device,
-        dtype: torch.dtype,
-    ):
-        self.max_seq_len = max_seq_len
-        self.k = torch.zeros(
-            n_layers,
-            max_batch_size,
-            max_seq_len,
-            n_kv_heads,
-            head_dim,
-            device=device,
-            dtype=dtype,
-        )
-        self.v = torch.zeros(
-            n_layers,
-            max_batch_size,
-            max_seq_len,
-            n_kv_heads,
-            head_dim,
-            device=device,
-            dtype=dtype,
-        )
-        self._slot_len: Dict[int, int] = {}
-        self._task_slot: Dict[str, int] = {}
-        self._free_slots = list(range(max_batch_size))
-        self._device = device
-
-    def task_alloc(self, task_id: str, prompt_ids: List[int]) -> bool:
-        if not self._free_slots:
-            return False
-        slot = self._free_slots.pop(0)
-        self._task_slot[task_id] = slot
-        self._slot_len[slot] = 0
-        return True
-
-    def task_free(self, task_id: str):
-        slot = self._task_slot.pop(task_id, None)
-        if slot is not None:
-            self._slot_len.pop(slot, None)
-            self._free_slots.append(slot)
-
-    def task_extend(self, task_id: str, pos: int) -> bool:
-        return pos < self.max_seq_len
-
-    def bind_tasks(
-        self, task_ids: List[str], total_len: int, device: torch.device
-    ) -> ContiguousCacheView:
-        slots = [self._task_slot[tid] for tid in task_ids]
-        batch_indices = torch.tensor(slots, dtype=torch.long, device=device)
-        return ContiguousCacheView(self, batch_indices, total_len)

astrai/inference/core/executor.py

@@ -1,122 +0,0 @@
-import logging
-from typing import List, Optional
-
-import torch
-
-from astrai.inference.core.cache import KVCache
-from astrai.inference.core.task import Task
-from astrai.inference.sample import sample
-from astrai.model.automodel import AutoModel
-from astrai.tokenize.tokenizer import AutoTokenizer
-
-logger = logging.getLogger(__name__)
-
-
-class Executor:
-    """Model forward passes for prefill and decode phases."""
-
-    def __init__(
-        self,
-        model: AutoModel,
-        tokenizer: AutoTokenizer,
-        kv_cache: KVCache,
-        device: Optional[str] = None,
-        dtype: Optional[torch.dtype] = None,
-    ):
-        self.model = model
-        self.tokenizer = tokenizer
-        self.kv_cache = kv_cache
-        self.device = device or next(model.parameters()).device
-        self.dtype = dtype or next(model.parameters()).dtype
-
-    def execute_prefill(self, tasks: List[Task], prompt_len: int, start_pos: int = 0):
-        if start_pos >= prompt_len:
-            return
-
-        tasks = sorted(tasks, key=lambda t: t.task_id)
-        batch_sz = len(tasks)
-
-        input_ids = torch.tensor(
-            [t.prompt_ids[start_pos:prompt_len] for t in tasks],
-            dtype=torch.long,
-            device=self.device,
-        )
-
-        task_ids = [t.task_id for t in tasks]
-
-        with torch.inference_mode():
-            self.model(
-                input_ids,
-                position_ids=torch.arange(
-                    start_pos, prompt_len, dtype=torch.long, device=self.device
-                )
-                .unsqueeze(0)
-                .expand(batch_sz, -1),
-                paged_cache=self.kv_cache.bind_tasks(task_ids, prompt_len, self.device),
-            )
-
-    def execute_decode(self, tasks: List[Task]) -> List[int]:
-        if not tasks:
-            return []
-
-        input_ids = torch.tensor(
-            [t.output_ids[-1] if t.output_ids else t.prompt_ids[-1] for t in tasks],
-            dtype=torch.long,
-            device=self.device,
-        )
-
-        position_ids = torch.tensor(
-            [t.next_pos for t in tasks], dtype=torch.long, device=self.device
-        )
-        total_len = position_ids.max().item() + 1
-
-        task_ids = [t.task_id for t in tasks]
-
-        temperatures = torch.tensor([t.temperature for t in tasks], device=self.device)
-        top_ks = torch.tensor([t.top_k for t in tasks], device=self.device)
-        top_ps = torch.tensor([t.top_p for t in tasks], device=self.device)
-        freq_penalties = torch.tensor(
-            [t.frequency_penalty for t in tasks], device=self.device
-        )
-
-        history_lists = []
-        mask_lists = []
-        for t in tasks:
-            window = t.rep_window
-            prompt_part = t.prompt_ids[-window:]
-            ids = prompt_part + t.output_ids
-            history_lists.append(ids)
-            mask_lists.append([True] * len(ids))
-
-        max_len = max(len(h) for h in history_lists)
-        padded_ids = torch.zeros(
-            len(tasks), max_len, dtype=torch.long, device=self.device
-        )
-        padded_mask = torch.zeros(
-            len(tasks), max_len, dtype=torch.bool, device=self.device
-        )
-        for i, (h, m) in enumerate(zip(history_lists, mask_lists)):
-            padded_ids[i, : len(h)] = torch.tensor(
-                h, dtype=torch.long, device=self.device
-            )
-            padded_mask[i, : len(m)] = torch.tensor(
-                m, dtype=torch.bool, device=self.device
-            )
-
-        with torch.inference_mode():
-            outputs = self.model(
-                input_ids.unsqueeze(1),
-                paged_cache=self.kv_cache.bind_tasks(task_ids, total_len, self.device),
-                position_ids=position_ids.unsqueeze(1),
-            )
-            logits = outputs["logits"][:, -1, :]
-
-        return sample(
-            logits,
-            temperature=temperatures,
-            top_k=top_ks,
-            top_p=top_ps,
-            frequency_penalty=freq_penalties,
-            input_ids=padded_ids,
-            input_mask=padded_mask,
-        ).tolist()

astrai/inference/core/scheduler.py

@@ -1,202 +0,0 @@
-import logging
-import threading
-from typing import Any, Dict, List, Optional, Tuple
-
-import torch
-
-from astrai.inference.core.cache import ContiguousCache, KVCache
-from astrai.inference.core.executor import Executor
-from astrai.inference.core.task import STOP, Task, TaskManager, TaskStatus
-from astrai.model.automodel import AutoModel
-from astrai.tokenize.tokenizer import AutoTokenizer
-
-logger = logging.getLogger(__name__)
-
-
-class InferenceScheduler:
-    """Continuous batching loop: cleanup -> refill -> prefill -> decode (all groups)."""
-
-    def __init__(
-        self,
-        model: AutoModel,
-        tokenizer: AutoTokenizer,
-        max_batch_size: int = 16,
-        max_seq_len: Optional[int] = None,
-        max_prompt_len: int = 2048,
-        device: Optional[str] = None,
-        dtype: Optional[torch.dtype] = None,
-        cache: Optional[KVCache] = None,
-    ):
-        config = model.config
-
-        if max_seq_len is not None:
-            self.max_seq_len = max_seq_len
-        elif config.max_len is not None:
-            self.max_seq_len = config.max_len
-        else:
-            raise ValueError(
-                "max_seq_len must be provided either as argument "
-                "or in model config (config.max_len)"
-            )
-        self.device = device or next(model.parameters()).device
-        self.dtype = dtype or next(model.parameters()).dtype
-
-        head_dim = config.dim // config.n_heads
-
-        if cache is not None:
-            self._cache = cache
-        else:
-            self._cache = ContiguousCache(
-                config.n_layers,
-                max_batch_size,
-                self.max_seq_len,
-                config.n_kv_heads,
-                head_dim,
-                self.device,
-                self.dtype,
-            )
-
-        self._task_mgr = TaskManager(
-            tokenizer=tokenizer,
-            max_batch_size=max_batch_size,
-            max_seq_len=self.max_seq_len,
-            max_prompt_len=max_prompt_len,
-        )
-
-        self._executor = Executor(
-            model=model,
-            tokenizer=tokenizer,
-            kv_cache=self._cache,
-            device=self.device,
-            dtype=self.dtype,
-        )
-
-        self._stop_event = threading.Event()
-        self._loop_thread: Optional[threading.Thread] = None
-
-    def add_task(self, prompt: str, **kwargs) -> str:
-        return self._task_mgr.add_task(prompt, **kwargs)
-
-    def remove_task(self, task_id: str):
-        for task in self._task_mgr.remove_task(task_id):
-            self._cache.task_free(task.task_id)
-
-    def get_stats(self) -> Dict[str, Any]:
-        return self._task_mgr.get_stats()
-
-    def _run_generation_loop(self):
-        stop_ids = self._task_mgr.tokenizer.stop_ids
-        cache = self._cache
-        try:
-            while not self._stop_event.is_set():
-                finished = self._task_mgr.remove_finished_tasks(stop_ids)
-                for task in finished:
-                    cache.task_free(task.task_id)
-
-                active = self._task_mgr.get_active_tasks()
-                available = self._task_mgr.max_batch_size - len(active)
-                if available > 0:
-                    candidates = self._task_mgr.pull_candidates(available)
-                    failed = []
-                    for task in candidates:
-                        if cache.task_alloc(task.task_id, task.prompt_ids):
-                            self._task_mgr.activate(task)
-                        else:
-                            failed.append(task)
-                    if failed:
-                        self._task_mgr.return_to_waiting(failed)
-
-                if not self._task_mgr.has_work():
-                    self._task_mgr.wait_for_tasks(timeout=1.0)
-                    continue
-
-                to_prefill = [
-                    t
-                    for t in self._task_mgr.get_active_tasks()
-                    if t.output_tokens == 0
-                    and cache.task_cached(t.task_id) < len(t.prompt_ids)
-                ]
-                if to_prefill:
-                    for t in to_prefill:
-                        t.input_tokens = len(t.prompt_ids)
-
-                    groups: Dict[Tuple[int, int], List[Task]] = {}
-                    for t in to_prefill:
-                        key = (
-                            len(t.prompt_ids),
-                            cache.task_cached(t.task_id),
-                        )
-                        groups.setdefault(key, []).append(t)
-
-                    for (prompt_len, start_pos), group in groups.items():
-                        self._executor.execute_prefill(group, prompt_len, start_pos)
-                        start_logical_page = start_pos // getattr(
-                            cache, "page_size", 64
-                        )
-                        for t in group:
-                            cache.task_record_hashes(
-                                t.task_id, t.prompt_ids, start_logical_page
-                            )
-
-                pos_groups: Dict[int, List[Task]] = {}
-                for t in self._task_mgr.get_active_tasks():
-                    pos_groups.setdefault(t.next_pos, []).append(t)
-
-                for next_pos in sorted(pos_groups.keys()):
-                    group = sorted(pos_groups[next_pos], key=lambda t: t.task_id)
-
-                    valid: List[Task] = []
-                    for t in group:
-                        if cache.task_extend(t.task_id, t.next_pos):
-                            valid.append(t)
-                        else:
-                            t.status = TaskStatus.ABORTED
-                            self._task_mgr.invoke_callback(t.task_id, STOP)
-
-                    if valid:
-                        next_tokens = self._executor.execute_decode(valid)
-
-                        for t, ntok in zip(valid, next_tokens):
-                            t.output_ids.append(ntok)
-                            t.output_tokens += 1
-                            self._task_mgr.invoke_callback(
-                                t.task_id,
-                                self._task_mgr.tokenizer.decode([ntok]),
-                            )
-
-                        for t in valid:
-                            if t.is_finished(stop_ids):
-                                self._task_mgr.invoke_callback(t.task_id, STOP)
-
-        except Exception as e:
-            self._stop_event.set()
-            logger.error(f"Scheduler loop crashed: {e}", exc_info=True)
-            for task in self._task_mgr.get_active_tasks():
-                self._task_mgr.invoke_callback(task.task_id, STOP)
-                cache.task_free(task.task_id)
-            for task in self._task_mgr.get_waiting_tasks():
-                self._task_mgr.invoke_callback(task.task_id, STOP)
-            self._task_mgr.clear_queues()
-
-    def start(self):
-        if self._loop_thread is not None and self._loop_thread.is_alive():
-            return
-        self._stop_event.clear()
-        t = threading.Thread(target=self._run_generation_loop, daemon=True)
-        t.start()
-        self._loop_thread = t
-
-    def stop(self):
-        self._stop_event.set()
-        self._task_mgr.wake()
-        if self._loop_thread is not None:
-            self._loop_thread.join(timeout=2.0)
-        self._loop_thread = None
-        for task in self._task_mgr.get_active_tasks():
-            self._task_mgr.invoke_callback(task.task_id, STOP)
-            self._cache.task_free(task.task_id)
-        for task in self._task_mgr.get_waiting_tasks():
-            self._task_mgr.invoke_callback(task.task_id, STOP)
-        self._task_mgr.clear_queues()
-        if torch.cuda.is_available():
-            torch.cuda.empty_cache()

astrai/inference/engine.py

@@ -8,9 +8,10 @@ from typing import Any, AsyncGenerator, Dict, Generator, List, Optional, Tuple,
 import torch
 import torch.nn as nn
 
-from astrai.inference.core.cache import KVCache
-from astrai.inference.core.scheduler import InferenceScheduler
-from astrai.inference.core.task import STOP
+from astrai.extension import ATTN_BACKEND, AttentionBackend, get_backend
+from astrai.inference.cache import PagePool
+from astrai.inference.scheduler import InferenceScheduler
+from astrai.inference.task import STOP
 from astrai.tokenize import AutoTokenizer
 
 
@@ -64,44 +65,6 @@ class GenerateResult:
             return self.results.copy()
 
 
-class GenerationRequest:
-    """Request parameters for text generation."""
-
-    def __init__(
-        self,
-        messages: List[Dict[str, str]],
-        top_k: int = 50,
-        top_p: float = 1.0,
-        temperature: float = 1.0,
-        max_tokens: Optional[int] = None,
-        frequency_penalty: float = 0.0,
-        rep_window: int = 64,
-        stream: bool = False,
-    ):
-        if not (isinstance(top_k, int) and top_k >= 0):
-            raise ValueError("top_k must be a non-negative integer")
-        if not (0.0 <= top_p <= 1.0):
-            raise ValueError("top_p must be a float between 0.0 and 1.0")
-        if not (isinstance(temperature, (int, float)) and temperature > 0):
-            raise ValueError("temperature must be a positive number")
-        if not (
-            isinstance(frequency_penalty, (int, float))
-            and -2.0 <= frequency_penalty <= 2.0
-        ):
-            raise ValueError("frequency_penalty must be between -2.0 and 2.0")
-        if not (isinstance(rep_window, int) and rep_window > 0):
-            raise ValueError("rep_window must be a positive integer")
-
-        self.messages = messages
-        self.top_k = top_k
-        self.top_p = top_p
-        self.temperature = temperature
-        self.max_tokens = max_tokens
-        self.frequency_penalty = frequency_penalty
-        self.rep_window = rep_window
-        self.stream = stream
-
-
 class InferenceEngine:
     """Unified inference engine backed by continuous-batching scheduler."""
 
@@ -111,9 +74,9 @@ class InferenceEngine:
         tokenizer: AutoTokenizer,
         max_batch_size: int = 1,
         max_seq_len: Optional[int] = None,
-        max_prompt_len: int = 2048,
-        page_size: int = 128,
-        cache: Optional[KVCache] = None,
+        cache: Optional[PagePool] = None,
+        enable_cuda_graph: bool = True,
+        backend: Optional[Union[str, ATTN_BACKEND, AttentionBackend, type]] = None,
     ):
         self.model = model
         self.tokenizer = tokenizer
@@ -122,8 +85,9 @@ class InferenceEngine:
             tokenizer=self.tokenizer,
             max_batch_size=max_batch_size,
             max_seq_len=max_seq_len,
-            max_prompt_len=max_prompt_len,
             cache=cache,
+            enable_cuda_graph=enable_cuda_graph,
+            backend=backend,
         )
 
         self.scheduler.start()
@@ -149,28 +113,23 @@ class InferenceEngine:
         is_batch = isinstance(prompt, list)
         prompts = prompt if is_batch else [prompt]
 
-        if stream:
-            return self._generate_streaming(
-                prompts,
-                is_batch,
-                max_tokens,
-                temperature,
-                top_p,
-                top_k,
-                frequency_penalty,
-                rep_window,
-            )
-        else:
-            return self._generate_non_streaming(
-                prompts,
-                is_batch,
-                max_tokens,
-                temperature,
-                top_p,
-                top_k,
-                frequency_penalty,
-                rep_window,
-            )
+        if max_tokens is not None and max_tokens <= 0:
+            if stream:
+                return iter(())
+            results = [""] * len(prompts)
+            return results if is_batch else results[0]
+
+        return self._generate(
+            prompts,
+            is_batch,
+            stream,
+            max_tokens,
+            temperature,
+            top_p,
+            top_k,
+            frequency_penalty,
+            rep_window,
+        )
 
     def generate_async(
         self,
@@ -182,9 +141,10 @@ class InferenceEngine:
         frequency_penalty: float = 0.0,
         rep_window: int = 64,
     ) -> AsyncGenerator[str, None]:
-        sync_gen = self._generate_streaming(
+        sync_gen = self._generate(
             [prompt],
             False,
+            True,
             max_tokens,
             temperature,
             top_p,
@@ -196,51 +156,30 @@ class InferenceEngine:
         async def _agen():
             loop = asyncio.get_event_loop()
             while True:
-                token = await loop.run_in_executor(None, self._next_token, sync_gen)
+                token = await loop.run_in_executor(None, next, sync_gen, None)
                 if token is None:
                     break
                 yield token
 
         return _agen()
 
-    @staticmethod
-    def _next_token(gen: Generator) -> Optional[str]:
-        try:
-            return next(gen)
-        except StopIteration:
-            return None
-
-    def generate_with_request(
-        self, request: GenerationRequest
-    ) -> Union[Generator[str, None, None], str, List[str]]:
-        prompt = self.tokenizer.apply_chat_template(request.messages, tokenize=False)
-        return self.generate(
-            prompt=prompt,
-            stream=request.stream,
-            max_tokens=request.max_tokens,
-            temperature=request.temperature,
-            top_p=request.top_p,
-            top_k=request.top_k,
-            frequency_penalty=request.frequency_penalty,
-            rep_window=request.rep_window,
-        )
-
-    def _submit_tasks(
+    def _generate(
         self,
         prompts: List[str],
+        is_batch: bool,
+        stream: bool,
         max_tokens: Optional[int],
         temperature: float,
         top_p: float,
         top_k: int,
         frequency_penalty: float,
         rep_window: int,
-    ) -> Tuple[GenerateResult, List[str]]:
+    ) -> Union[Generator, str, List[str]]:
         n = len(prompts)
+        request_backend = get_backend(use_default=False)
         result = GenerateResult(count=n)
-        task_ids = []
-        for i, p in enumerate(prompts):
-            cb = self._make_callback(result, i)
-            task_id = self.scheduler.add_task(
+        task_ids = [
+            self.scheduler.add_task(
                 prompt=p,
                 max_tokens=max_tokens,
                 temperature=temperature,
@@ -248,99 +187,54 @@ class InferenceEngine:
                 top_k=top_k,
                 frequency_penalty=frequency_penalty,
                 rep_window=rep_window,
-                stream_callback=cb,
+                backend=request_backend,
+                stream_callback=lambda token, idx=i: result.append(token, idx),
             )
-            task_ids.append(task_id)
-        return result, task_ids
+            for i, p in enumerate(prompts)
+        ]
 
-    @staticmethod
-    def _make_callback(result: GenerateResult, idx: int):
-        def cb(token):
-            result.append(token, idx)
+        if not stream:
+            try:
+                result.wait_completion()
+            except TimeoutError:
+                for tid in task_ids:
+                    self.scheduler.remove_task(tid)
+                raise
+            for tid in task_ids:
+                self.scheduler.remove_task(tid)
+            res = result.get_results()
+            return res if is_batch else res[0]
 
-        return cb
-
-    def _generate_streaming(
-        self,
-        prompts: List[str],
-        is_batch: bool,
-        max_tokens: Optional[int],
-        temperature: float,
-        top_p: float,
-        top_k: int,
-        frequency_penalty: float,
-        rep_window: int,
-    ) -> Generator:
-        result, task_ids = self._submit_tasks(
-            prompts,
-            max_tokens,
-            temperature,
-            top_p,
-            top_k,
-            frequency_penalty,
-            rep_window,
-        )
-        n = len(prompts)
         remaining = n
         finished = [False] * n
 
         def gen():
             nonlocal remaining
-            try:
-                while remaining > 0:
-                    items = result.pop_all()
-                    for idx, token in items:
-                        if token is STOP:
-                            if not finished[idx]:
-                                finished[idx] = True
-                                remaining -= 1
-                        else:
-                            yield (idx, token) if is_batch else token
-                    if remaining > 0:
-                        result.wait(timeout=0.05)
-            finally:
-                for tid in task_ids:
-                    self.scheduler.remove_task(tid)
+            while remaining > 0:
+                items = result.pop_all()
+                for idx, token in items:
+                    if token is STOP:
+                        if not finished[idx]:
+                            finished[idx] = True
+                            remaining -= 1
+                    else:
+                        yield (idx, token) if is_batch else token
+                if remaining > 0:
+                    result.wait(timeout=0.05)
 
         return gen()
 
-    def _generate_non_streaming(
-        self,
-        prompts: List[str],
-        is_batch: bool,
-        max_tokens: Optional[int],
-        temperature: float,
-        top_p: float,
-        top_k: int,
-        frequency_penalty: float,
-        rep_window: int,
-    ) -> Union[str, List[str]]:
-        result, task_ids = self._submit_tasks(
-            prompts,
-            max_tokens,
-            temperature,
-            top_p,
-            top_k,
-            frequency_penalty,
-            rep_window,
-        )
-
-        try:
-            result.wait_completion()
-        except TimeoutError:
-            for tid in task_ids:
-                self.scheduler.remove_task(tid)
-            raise
-
-        for tid in task_ids:
-            self.scheduler.remove_task(tid)
-
-        res = result.get_results()
-        return res if is_batch else res[0]
-
     def get_stats(self) -> Dict[str, Any]:
         return self.scheduler.get_stats()
 
+    @property
+    def backend_name(self) -> str:
+        return self.scheduler.backend_name
+
+    @property
+    def cuda_graph_enabled(self) -> bool:
+        return self.scheduler.cuda_graph_enabled
+
     def shutdown(self):
         self.scheduler.stop()
         if torch.cuda.is_available():

astrai/inference/metrics.py

@@ -0,0 +1,201 @@
+"""Unified per-task perf/stats: timing records, context-manager scopes, aggregate reporting."""
+
+import time
+from collections import deque
+from contextlib import contextmanager
+from dataclasses import dataclass
+from typing import Any, Deque, Dict, Generator, List, Literal, Optional
+
+
+@dataclass
+class TaskTiming:
+    """Timestamp snapshots and computed metrics for one generation task.
+
+    Created by :class:`MetricsCollector` at task-registration time;
+    updated via ``record`` / ``mark_finished``.
+    """
+
+    task_id: str
+    arrival_time: float
+    prefill_start_time: Optional[float] = None
+    first_token_time: Optional[float] = None
+    finish_time: Optional[float] = None
+    input_tokens: int = 0
+    output_tokens: int = 0
+    _decode_steps: int = 0
+    _decode_total_s: float = 0.0
+
+    # derived metrics
+
+    @property
+    def queue_wait_ms(self) -> Optional[float]:
+        if self.prefill_start_time is not None:
+            return (self.prefill_start_time - self.arrival_time) * 1000
+        return None
+
+    @property
+    def ttft_ms(self) -> Optional[float]:
+        if self.first_token_time is not None:
+            return (self.first_token_time - self.arrival_time) * 1000
+        return None
+
+    @property
+    def prefill_tps(self) -> Optional[float]:
+        if self.prefill_start_time is not None and self.first_token_time is not None:
+            d = self.first_token_time - self.prefill_start_time
+            if d > 0 and self.input_tokens > 0:
+                return self.input_tokens / d
+        return None
+
+    @property
+    def decode_tps(self) -> Optional[float]:
+        if self.first_token_time is not None and self.finish_time is not None:
+            d = self.finish_time - self.first_token_time
+            dt = self.output_tokens - 1
+            if dt > 0 and d > 0:
+                return dt / d
+        return None
+
+    @property
+    def decode_avg_ms(self) -> Optional[float]:
+        if self._decode_steps > 0 and self._decode_total_s > 0:
+            return (self._decode_total_s / self._decode_steps) * 1000
+        return None
+
+    @property
+    def e2e_latency_ms(self) -> Optional[float]:
+        if self.finish_time is not None:
+            return (self.finish_time - self.arrival_time) * 1000
+        return None
+
+    @property
+    def total_tps(self) -> Optional[float]:
+        if self.finish_time is not None:
+            total = self.input_tokens + self.output_tokens
+            d = self.finish_time - self.arrival_time
+            if total > 0 and d > 0:
+                return total / d
+        return None
+
+    def to_dict(self) -> Dict[str, Any]:
+        return {
+            "task_id": self.task_id,
+            "input_tokens": self.input_tokens,
+            "output_tokens": self.output_tokens,
+            "queue_wait_ms": (
+                round(self.queue_wait_ms, 2) if self.queue_wait_ms is not None else None
+            ),
+            "ttft_ms": (round(self.ttft_ms, 2) if self.ttft_ms is not None else None),
+            "prefill_tps": (
+                round(self.prefill_tps, 2) if self.prefill_tps is not None else None
+            ),
+            "decode_tps": (
+                round(self.decode_tps, 2) if self.decode_tps is not None else None
+            ),
+            "decode_avg_ms": (
+                round(self.decode_avg_ms, 2) if self.decode_avg_ms is not None else None
+            ),
+            "total_tps": (
+                round(self.total_tps, 2) if self.total_tps is not None else None
+            ),
+            "e2e_latency_ms": (
+                round(self.e2e_latency_ms, 2)
+                if self.e2e_latency_ms is not None
+                else None
+            ),
+        }
+
+
+class MetricsCollector:
+    """Single-owner perf/stats hub for all generation tasks.
+
+    Usage::
+
+        metrics = MetricsCollector()
+        metrics.register(task_id, arrival_time)
+
+        with metrics.record(task_ids, "prefill"):
+            run_prefill(...)
+
+        metrics.mark_finished(task_id, input_tokens, output_tokens)
+
+        stats = metrics.get_stats()
+    """
+
+    def __init__(self, max_recent: int = 128):
+        self._timings: Dict[str, TaskTiming] = {}
+        self._completed: Deque[TaskTiming] = deque(maxlen=max_recent)
+
+        self._ttft_ms_sum = 0.0
+        self._ttft_ms_count = 0
+        self._decode_tps_sum = 0.0
+        self._decode_tps_count = 0
+        self._e2e_ms_sum = 0.0
+        self._e2e_ms_count = 0
+
+    def register(self, task_id: str):
+        """Create a timing record for a newly-created task."""
+        self._timings[task_id] = TaskTiming(task_id=task_id, arrival_time=time.time())
+
+    def mark_finished(self, task_id: str, input_tokens: int, output_tokens: int):
+        """Close timing for a finished/aborted task and move it to completed."""
+        timing = self._timings.pop(task_id, None)
+        if timing is None:
+            return
+        timing.finish_time = time.time()
+        timing.input_tokens = input_tokens
+        timing.output_tokens = output_tokens
+        self._completed.append(timing)
+        self._accumulate(timing)
+
+    # timing scopes
+
+    @contextmanager
+    def record(
+        self, task_ids: List[str], phase: Literal["prefill", "decode"]
+    ) -> Generator[None, None, None]:
+        tic = time.time()
+        yield
+        toc = time.time()
+        dt = toc - tic
+        for tid in task_ids:
+            t = self._timings.get(tid)
+            if t is None:
+                continue
+            if phase == "prefill":
+                t.prefill_start_time = tic
+                t.first_token_time = toc
+            elif phase == "decode":
+                t._decode_steps += 1
+                t._decode_total_s += dt
+
+    # aggregate stats
+
+    def get_stats(self) -> Dict[str, Any]:
+        stats: Dict[str, Any] = {}
+        if self._ttft_ms_count > 0:
+            stats["avg_ttft_ms"] = round(self._ttft_ms_sum / self._ttft_ms_count, 2)
+        if self._decode_tps_count > 0:
+            stats["avg_decode_tps"] = round(
+                self._decode_tps_sum / self._decode_tps_count, 2
+            )
+        if self._e2e_ms_count > 0:
+            stats["avg_e2e_latency_ms"] = round(
+                self._e2e_ms_sum / self._e2e_ms_count, 2
+            )
+        if self._completed:
+            stats["recent_tasks"] = [t.to_dict() for t in self._completed]
+        return stats
+
+    # internal
+
+    def _accumulate(self, t: TaskTiming):
+        if t.ttft_ms is not None:
+            self._ttft_ms_sum += t.ttft_ms
+            self._ttft_ms_count += 1
+        if t.decode_tps is not None:
+            self._decode_tps_sum += t.decode_tps
+            self._decode_tps_count += 1
+        if t.e2e_latency_ms is not None:
+            self._e2e_ms_sum += t.e2e_latency_ms
+            self._e2e_ms_count += 1

astrai/inference/network/__init__.py

@@ -4,8 +4,7 @@
 lazy singleton FastAPI instance.
 """
 
-from astrai.inference.api.protocol import GenContext, ProtocolHandler, StopChecker
-from astrai.inference.api.server import (
+from astrai.inference.network.app import (
     AnthropicMessage,
     ChatCompletionRequest,
     ChatMessage,
@@ -15,7 +14,8 @@ from astrai.inference.api.server import (
     get_app,
     run_server,
 )
-from astrai.inference.api.tool_parser import (
+from astrai.inference.network.protocol import GenContext, ProtocolHandler, StopChecker
+from astrai.inference.network.tool_parser import (
     BaseToolParser,
     SimpleJsonToolParser,
     ToolParserFactory,

astrai/inference/network/anthropic.py

@@ -6,13 +6,13 @@ from typing import Any, Dict, List, Tuple, Union
 
 from pydantic import BaseModel
 
-from astrai.inference.api.protocol import (
+from astrai.inference.engine import InferenceEngine
+from astrai.inference.network.protocol import (
     GenContext,
     ResponseBuilder,
     StopInfo,
     sse_event,
 )
-from astrai.inference.engine import InferenceEngine
 
 
 def _extract_text(content: Union[str, List[Dict[str, Any]]]) -> str:

astrai/inference/network/app.py

@@ -18,10 +18,10 @@ import uvicorn
 from fastapi import APIRouter, FastAPI, HTTPException
 from pydantic import BaseModel, Field
 
-from astrai.inference.api.anthropic import AnthropicResponseBuilder
-from astrai.inference.api.openai import OpenAIResponseBuilder
-from astrai.inference.api.protocol import ProtocolHandler
 from astrai.inference.engine import InferenceEngine
+from astrai.inference.network.anthropic import AnthropicResponseBuilder
+from astrai.inference.network.openai import OpenAIResponseBuilder
+from astrai.inference.network.protocol import ProtocolHandler
 from astrai.model import AutoModel
 from astrai.tokenize import AutoTokenizer
 
@@ -110,6 +110,7 @@ def _create_engine(
     device: str = "cuda",
     dtype: torch.dtype = torch.bfloat16,
     max_batch_size: int = 16,
+    max_seq_len: Optional[int] = None,
 ) -> InferenceEngine:
     if not param_path.exists():
         raise FileNotFoundError(f"Parameter directory not found: {param_path}")
@@ -123,6 +124,7 @@ def _create_engine(
         model=model,
         tokenizer=tokenizer,
         max_batch_size=max_batch_size,
+        max_seq_len=max_seq_len,
     )
     logger.info(f"Inference engine initialized with max_batch_size={max_batch_size}")
     return engine
@@ -186,6 +188,7 @@ def run_server(
     device: str = "cuda",
     dtype: torch.dtype = torch.bfloat16,
     max_batch_size: int = 16,
+    max_seq_len: Optional[int] = None,
 ):
     app = get_app()
     app.state.server_config = {
@@ -193,6 +196,7 @@ def run_server(
         "dtype": dtype,
         "param_path": param_path,
         "max_batch_size": max_batch_size,
+        "max_seq_len": max_seq_len,
     }
     uvicorn.run(
         app,

astrai/inference/network/openai.py

@@ -7,14 +7,14 @@ from typing import Any, Dict, List, Optional, Tuple, Union
 
 from pydantic import BaseModel
 
-from astrai.inference.api.protocol import (
+from astrai.inference.engine import InferenceEngine
+from astrai.inference.network.protocol import (
     GenContext,
     ResponseBuilder,
     StopInfo,
     sse_event,
 )
-from astrai.inference.api.tool_parser import BaseToolParser, ToolParserFactory
-from astrai.inference.engine import InferenceEngine
+from astrai.inference.network.tool_parser import BaseToolParser, ToolParserFactory
 
 logger = logging.getLogger(__name__)
 

astrai/inference/network/protocol.py

@@ -181,12 +181,10 @@ class ProtocolHandler:
         self, agen: AsyncGenerator, ctx: GenContext, stop_sequences: List[str]
     ) -> Dict[str, Any]:
         checker = StopChecker(stop_sequences)
-        chunks: List[str] = []
         body = ""
         matched = None
 
         async for token in agen:
-            chunks.append(token)
             body += token
 
             matched = checker.check(body)
@@ -195,6 +193,5 @@ class ProtocolHandler:
 
             ctx.completion_tokens += 1
 
-        content = "".join(chunks)
         stop = StopInfo(matched=matched, body=body)
-        return self.builder.format_response(ctx, content, stop)
+        return self.builder.format_response(ctx, body, stop)

astrai/inference/network/tool_parser.py

@@ -7,6 +7,7 @@ Subclasses may optionally consume ``token_ids`` for token-level parsing
 (e.g. Harmony / VLM-style parsers).
 """
 
+import json
 import re
 import uuid
 from abc import ABC, abstractmethod
@@ -21,13 +22,10 @@ class BaseToolParser(ABC):
     Maintains streaming state internally so that each call to :meth:`feed`
     can diff against previously emitted content.
 
-    Parameters
-    ----------
-    tools : list of dict, optional
-        Tool definitions from the request.
-    tool_choice : str
-        ``"auto"`` / ``"required"`` / ``"none"`` or a named tool choice
-        dict.
+    Args:
+        tools (list of dict, optional): Tool definitions from the request.
+        tool_choice (str): ``"auto"`` / ``"required"`` / ``"none"`` or a named
+            tool choice dict.
     """
 
     def __init__(self, tools: Optional[List[Dict]] = None, tool_choice: str = "auto"):
@@ -50,14 +48,12 @@ class BaseToolParser(ABC):
 
         Returns an empty list when nothing new should be emitted.
 
-        Parameters
-        ----------
-        body : str
-            The complete accumulated generated text so far.
-        current_token_ids : list of int, optional
-            All token IDs decoded into *body* (cumulative).
-        delta_token_ids : list of int, optional
-            Only the token IDs for this chunk.
+        Args:
+            body (str): The complete accumulated generated text so far.
+            current_token_ids (list of int, optional): All token IDs decoded
+                into *body* (cumulative).
+            delta_token_ids (list of int, optional): Only the token IDs for
+                this chunk.
         """
 
     @abstractmethod
@@ -117,6 +113,29 @@ def _parse_tool_call_json(json_str: str, complete: bool):
 
     Returns ``(name, args, valid)``.
     """
+    if complete:
+        try:
+            obj = json.loads(json_str)
+        except json.JSONDecodeError:
+            return None, "", False
+        name = obj.get("name")
+        if not isinstance(name, str) or not name:
+            return None, "", False
+        args = obj.get("arguments")
+        if isinstance(args, dict):
+            if not args:
+                args = ""
+            else:
+                args = json.dumps(args, ensure_ascii=False)
+                args = args[1:-1].rstrip()
+        elif isinstance(args, list):
+            args = json.dumps(args, ensure_ascii=False) if args else ""
+        elif isinstance(args, str):
+            pass
+        else:
+            args = str(args) if args is not None else ""
+        return name, args, True
+
     name_match = re.search(r'"name"\s*:\s*"([^"]*)"', json_str)
     if not name_match:
         return None, "", False
@@ -127,8 +146,6 @@ def _parse_tool_call_json(json_str: str, complete: bool):
         return name, "", True
 
     raw = args_match.group(1).rstrip()
-    if complete and raw.endswith("}"):
-        raw = raw[:-1].rstrip()
     if raw.startswith("{"):
         inner = raw[1:].rstrip()
         if inner.endswith("}"):
@@ -156,9 +173,6 @@ def _find_tool_calls(text: str, start_pos: int = 0):
             break
 
         json_str = text[brace:end]
-        if not _TOOL_CALL_HEAD_RE.search(json_str):
-            pos = end
-            continue
 
         name, args, valid = _parse_tool_call_json(json_str, complete=True)
         if not valid or name is None:
@@ -186,7 +200,7 @@ def _find_partial_tool_call(text: str, start_pos: int = 0):
         return None
 
     json_str = text[brace:]
-    if not _TOOL_CALL_HEAD_RE.search(json_str):
+    if '"name"' not in json_str:
         return None
 
     name, args, valid = _parse_tool_call_json(json_str, complete=False)

astrai/inference/runtime/__init__.py

@@ -0,0 +1,25 @@
+"""Execution primitives: forward passes, CUDA graphs, and sampling."""
+
+from astrai.inference.runtime.executor import Executor
+from astrai.inference.runtime.graph import CudaGraphContext
+from astrai.inference.runtime.sample import (
+    BaseSamplingStrategy,
+    FrequencyPenaltyStrategy,
+    SamplingPipeline,
+    TemperatureStrategy,
+    TopKStrategy,
+    TopPStrategy,
+    sample,
+)
+
+__all__ = [
+    "Executor",
+    "CudaGraphContext",
+    "BaseSamplingStrategy",
+    "FrequencyPenaltyStrategy",
+    "SamplingPipeline",
+    "TemperatureStrategy",
+    "TopKStrategy",
+    "TopPStrategy",
+    "sample",
+]

astrai/inference/runtime/executor.py

@@ -0,0 +1,443 @@
+import logging
+import time
+from contextlib import contextmanager
+from dataclasses import dataclass
+from typing import List, Optional
+
+import torch
+from torch import Tensor
+
+from astrai.extension.backend.attention import (
+    CudaBackend,
+    get_backend,
+)
+from astrai.inference.cache import PagePool, TaskCacheManager
+from astrai.inference.runtime.graph import CudaGraphContext
+from astrai.inference.runtime.sample import sample
+from astrai.inference.task import Task
+from astrai.inference.workspace import InferenceWorkspace
+from astrai.model.automodel import AutoModel
+
+logger = logging.getLogger(__name__)
+
+
+@contextmanager
+def timed(label: str, log: Optional[logging.Logger] = None):
+    """GPU-precise timer via CUDA events; falls back to perf_counter on CPU."""
+    log = log or logger
+    if not log.isEnabledFor(logging.DEBUG):
+        yield
+        return
+    use_cuda = torch.cuda.is_available()
+    if use_cuda:
+        start = torch.cuda.Event(enable_timing=True)
+        end = torch.cuda.Event(enable_timing=True)
+        start.record()
+    else:
+        tic = time.perf_counter()
+    yield
+    if use_cuda:
+        end.record()
+        torch.cuda.synchronize()
+        elapsed_ms = start.elapsed_time(end)
+    else:
+        elapsed_ms = (time.perf_counter() - tic) * 1000
+    log.debug("%s %.2fms", label, elapsed_ms)
+
+
+@dataclass
+class SamplingBatchInfo:
+    """Per-batch sampling parameters, cached across decode steps.
+
+    Sampling params are constant for a given ordered task set, so they are
+    built once (pinned-memory async H2D) and reused until the task set
+    changes.  ``top_ks`` is int32 to match the native consumers.
+    """
+
+    temperatures: Tensor  # float32 [B]
+    top_ks: Tensor  # int32  [B]
+    top_ps: Tensor  # float32 [B]
+    freq_penalties: Tensor  # float32 [B]
+    has_freq: bool  # any frequency_penalty != 0 (avoids per-step GPU .any())
+
+
+@dataclass
+class DecodeSteadyState:
+    """Cached decode metadata for the steady-state case.
+
+    When the same ordered task set decodes one token per step, sampling
+    params and task signature are reused; only positions advance by 1.
+    ``last_tokens`` keeps that step's sampled ids on-device so the next
+    step with an unchanged signature can fill ``input_ids`` via a
+    device-to-device copy.
+    """
+
+    task_sig: tuple
+    positions: list[int]
+    sampling_info: SamplingBatchInfo
+    last_tokens: Optional[Tensor] = None
+
+
+def _build_sampling_batch_info(tasks: List[Task], device) -> SamplingBatchInfo:
+    pin = str(device).startswith("cuda")
+    freq_penalties = torch.tensor(
+        [t.frequency_penalty for t in tasks], dtype=torch.float32, pin_memory=pin
+    ).to(device, non_blocking=True)
+    return SamplingBatchInfo(
+        temperatures=torch.tensor(
+            [t.temperature for t in tasks], dtype=torch.float32, pin_memory=pin
+        ).to(device, non_blocking=True),
+        top_ks=torch.tensor(
+            [t.top_k for t in tasks], dtype=torch.int32, pin_memory=pin
+        ).to(device, non_blocking=True),
+        top_ps=torch.tensor(
+            [t.top_p for t in tasks], dtype=torch.float32, pin_memory=pin
+        ).to(device, non_blocking=True),
+        freq_penalties=freq_penalties,
+        has_freq=bool((freq_penalties != 0).any()),
+    )
+
+
+def _warmup_cuda_graphs(
+    model: AutoModel,
+    pool: PagePool,
+    task_cache: TaskCacheManager,
+    ws: InferenceWorkspace,
+    gctx: CudaGraphContext,
+    max_batch_size: int,
+    prompt_len: int = 1,
+    device: Optional[str] = None,
+):
+    dev = device or next(model.parameters()).device
+
+    # Prefill warmup: cuBLAS auto-tunes for the actual prompt-length tensor
+    # shapes on first call (F.linear is the dominant cost).  This also warms
+    # up the CUDA context (driver init) and compiles the graph-capture trace
+    # that follows.  Custom .so kernels do NOT need this — they are pre-built.
+    warmup_len = 64
+    tid = "_warmup_prefill"
+    if task_cache.task_alloc(tid, list(range(warmup_len))):
+        with (
+            torch.inference_mode(),
+            timed("warmup prefill", logger),
+        ):
+            kv = task_cache.bind([tid], ws, start_pos=0)
+            ids_in = torch.arange(warmup_len, device=dev)
+            pos_in = ids_in
+            model(
+                ids_in,
+                kv_cache=kv,
+                position_ids=pos_in,
+                fwd="prefill",
+            )
+        task_cache.task_free(tid)
+
+    batch_sizes = [1]
+    n = 2
+    while n <= max_batch_size:
+        batch_sizes.append(n)
+        n *= 2
+    if max_batch_size not in batch_sizes:
+        batch_sizes.append(max_batch_size)
+
+    for b in batch_sizes:
+        task_ids = [f"_warmup_decode_{b}_{i}" for i in range(b)]
+        prompt_tokens = [list(range(prompt_len)) for _ in range(b)]
+        alloc_ok = True
+        for tid, pt in zip(task_ids, prompt_tokens):
+            if not task_cache.task_alloc(tid, pt):
+                alloc_ok = False
+                break
+        if not alloc_ok:
+            for tid in task_ids:
+                task_cache.task_free(tid)
+            continue
+
+        with (
+            torch.inference_mode(),
+            timed(f"warmup decode b={b}", logger),
+        ):
+            for step in range(2):
+                seq_pos = step
+                ws.position_ids[:b] = seq_pos
+                for tid in task_ids:
+                    task_cache.task_extend(tid, seq_pos)
+                kv = task_cache.bind(task_ids, ws)
+                ids_buf = ws.fill_input_ids([step] * b)
+                gctx.forward(
+                    model,
+                    key=(b,),
+                    input_ids=ids_buf,
+                    kv_cache=kv,
+                    position_ids=ws.position_ids[:b],
+                    fwd="decode",
+                )
+
+        for tid in task_ids:
+            task_cache.task_free(tid)
+        torch.cuda.synchronize()
+
+
+class Executor:
+    """Model forward passes for prefill and decode phases."""
+
+    def __init__(
+        self,
+        model: AutoModel,
+        kv_cache: PagePool,
+        task_cache: TaskCacheManager,
+        device: Optional[str] = None,
+        dtype: Optional[torch.dtype] = None,
+        enable_cuda_graph: bool = True,
+    ):
+        self.model = model
+        self.kv_cache = kv_cache
+        self.task_cache = task_cache
+        self.device = device or next(model.parameters()).device
+        self.dtype = dtype or next(model.parameters()).dtype
+
+        # Per-step decode cache for the steady-state case (same ordered
+        # task set decodes one token per step).  Sampling params stay
+        # constant; only positions advance.
+        self._decode_cache: Optional[DecodeSteadyState] = None
+
+        # Pre-allocated fixed-shape buffers for the decode hot path
+        # (input_ids, decode mask, KV bind metadata).  Eagerly sized at init
+        # so the workspace is CUDA-graph-capture friendly — no allocation
+        # during capture.
+        config = model.config
+        max_q_heads = config.num_attention_heads
+        head_dim = config.hidden_size // config.num_attention_heads
+        backend = get_backend()
+        self._graph_supported = backend.supports_graph() and (
+            CudaBackend.available() and head_dim in CudaBackend.HEAD_DIMS
+        )
+        self._workspace = InferenceWorkspace(
+            max_batch_size=kv_cache.max_batch_size,
+            max_seq_len=kv_cache.max_seq_len,
+            max_q_heads=max_q_heads,
+            head_dim=head_dim,
+            device=self.device,
+            dtype=self.dtype,
+        )
+
+        # CUDA-graph capture: one graph per (batch_size,) key.
+        # Enabled at init-time via _warmup_cuda_graphs for CudaBackend
+        # on supported head_dims; left disabled otherwise.
+        self._graph_ctx = CudaGraphContext()
+        if enable_cuda_graph:
+            self._try_enable_cuda_graph()
+
+    def _try_enable_cuda_graph(self):
+        if not self._graph_supported:
+            return
+
+        self._graph_ctx.set_enabled(True)
+        _warmup_cuda_graphs(
+            self.model,
+            self.kv_cache,
+            self.task_cache,
+            self._workspace,
+            self._graph_ctx,
+            max_batch_size=self.kv_cache.max_batch_size,
+            device=self.device,
+        )
+
+    @property
+    def cuda_graph_enabled(self) -> bool:
+        return self._graph_ctx.enabled and self._graph_supported
+
+    def _sample_logits(
+        self,
+        logits: Tensor,
+        tasks: List[Task],
+        return_logprobs: bool = False,
+        info: Optional[SamplingBatchInfo] = None,
+    ):
+        """Sample from ``logits`` and return ``(host_payload, tokens)``.
+
+        ``host_payload`` is the scheduler-facing list (token ids, or
+        ``(token_id, logprob)`` tuples with ``return_logprobs``);
+        ``tokens`` is the ``[B]`` device tensor that produced it, kept
+        for the steady-state decode fast path.
+        """
+        info = info or _build_sampling_batch_info(tasks, self.device)
+        if info.has_freq:
+            history_lists = [
+                t.prompt_ids[-t.rep_window :] + t.output_ids for t in tasks
+            ]
+            history_lens = [len(ids) for ids in history_lists]
+            max_len = max(history_lens, default=0)
+            padded_ids = torch.zeros(
+                len(tasks), max_len, dtype=torch.long, device=self.device
+            )
+            padded_mask = torch.zeros(
+                len(tasks), max_len, dtype=torch.bool, device=self.device
+            )
+            for i, ids in enumerate(history_lists):
+                length = len(ids)
+                padded_ids[i, :length] = torch.as_tensor(
+                    ids, dtype=torch.long, device=self.device
+                )
+                padded_mask[i, :length] = True
+        else:
+            padded_ids = None
+            padded_mask = None
+
+        result = sample(
+            logits,
+            temperature=info.temperatures,
+            top_k=info.top_ks,
+            top_p=info.top_ps,
+            frequency_penalty=info.freq_penalties,
+            input_ids=padded_ids,
+            input_mask=padded_mask,
+            return_logprobs=return_logprobs,
+        )
+        if not return_logprobs:
+            return result.tolist(), result
+
+        tokens, logprobs = result
+        tokens_list = tokens.tolist()
+        logprobs_list = logprobs.tolist()
+        for task, logprob in zip(tasks, logprobs_list):
+            task.output_logprobs.append(float(logprob))
+        return list(zip(tokens_list, logprobs_list)), tokens
+
+    def execute_prefill(
+        self,
+        tasks: List[Task],
+        prompt_len: int,
+        start_pos: int = 0,
+        return_logprobs: bool = False,
+    ):
+        if start_pos >= prompt_len:
+            return []
+
+        tasks = sorted(tasks, key=lambda t: t.task_id)
+        batch_sz = len(tasks)
+
+        input_ids = torch.tensor(
+            [token for t in tasks for token in t.prompt_ids[start_pos:prompt_len]],
+            dtype=torch.long,
+            device=self.device,
+        )
+
+        task_ids = [t.task_id for t in tasks]
+        position_ids = torch.arange(
+            start_pos, prompt_len, dtype=torch.long, device=self.device
+        ).repeat(batch_sz)
+
+        with (
+            torch.inference_mode(),
+            timed(f"execute_prefill b={batch_sz} prompt_len={prompt_len}", logger),
+        ):
+            outputs = self.model(
+                input_ids,
+                position_ids=position_ids,
+                kv_cache=self.task_cache.bind(
+                    task_ids,
+                    self._workspace,
+                    start_pos=start_pos,
+                ),
+                fwd="prefill",
+            )
+            q_len = prompt_len - start_pos
+            logits = outputs["logits"][
+                torch.arange(1, batch_sz + 1, device=self.device) * q_len - 1
+            ]
+
+        step_out, _ = self._sample_logits(logits, tasks, return_logprobs)
+        return tasks, step_out
+
+    def execute_decode(
+        self, tasks: List[Task], return_logprobs: bool = False
+    ) -> List[int]:
+        """Decode next token for each task.
+
+        Args:
+            return_logprobs: When ``True``, also record (and return)
+                the log-probability of each sampled token under the
+                post-strategy sampling distribution.  The logprob is
+                appended to ``task.output_logprobs`` and the return
+                list becomes ``List[Tuple[int, float]]``.
+
+        Returns:
+            ``List[int]`` of sampled token IDs, or
+            ``List[Tuple[int, float]]`` of ``(token_id, logprob)`` when
+            ``return_logprobs`` is ``True``.
+        """
+        if not tasks:
+            return []
+
+        b = len(tasks)
+        ws = self._workspace
+        task_ids = [t.task_id for t in tasks]
+        cur_positions = [t.next_pos for t in tasks]
+        task_sig = tuple(task_ids)
+
+        # ---- pre-replay: update input buffers in-place ----
+
+        # When the previous decode step ran this same ordered task set, its
+        # sampled tokens are still on-device and map 1:1 onto the current
+        # slots — fill input ids device-to-device.  inference_mode guards
+        # the read because the source was produced under sampling's
+        # inference-mode context.
+        cached = self._decode_cache
+        sig_match = cached is not None and cached.task_sig == task_sig
+        if sig_match and cached.last_tokens is not None:
+            with torch.inference_mode():
+                input_ids = ws.fill_input_ids_from_device(cached.last_tokens)
+        else:
+            input_ids = ws.fill_input_ids(
+                [t.output_ids[-1] if t.output_ids else t.prompt_ids[-1] for t in tasks]
+            )
+
+        kv_cache = self.task_cache.bind(task_ids, ws)
+
+        reuse_decode_state = self.task_cache.bind_was_steady and sig_match
+        if reuse_decode_state:
+            info = self._decode_cache.sampling_info
+            ws.position_ids[:b] += 1
+        else:
+            info = _build_sampling_batch_info(tasks, self.device)
+            ws.position_ids[:b].copy_(
+                torch.tensor(cur_positions, dtype=torch.long, device=self.device)
+            )
+        self._decode_cache = DecodeSteadyState(task_sig, cur_positions, info)
+
+        # ---- forward (graph replay or live run + capture) ----
+
+        use_graph = (
+            self._graph_ctx.enabled
+            and self._graph_supported
+            and get_backend().supports_graph()
+        )
+        key = (b,)
+        with (
+            torch.inference_mode(),
+            timed(f"execute_decode forward b={b}", logger),
+        ):
+            if use_graph:
+                outputs = self._graph_ctx.forward(
+                    self.model,
+                    key=key,
+                    input_ids=input_ids,
+                    kv_cache=kv_cache,
+                    position_ids=ws.position_ids[:b],
+                    fwd="decode",
+                )
+            else:
+                outputs = self.model(
+                    input_ids,
+                    kv_cache=kv_cache,
+                    position_ids=ws.position_ids[:b],
+                    fwd="decode",
+                )
+            logits = outputs["logits"]
+
+        step_out, tokens_dev = self._sample_logits(
+            logits, tasks, return_logprobs, info=info
+        )
+        self._decode_cache.last_tokens = tokens_dev
+        return step_out

astrai/inference/runtime/graph.py

@@ -0,0 +1,103 @@
+"""CUDA-graph capture for the decode model-forward step.
+
+Mirrors SGLang's cuda-graph manager: one graph per batch size.  The graph
+pair.  The graph captures ``model.forward()`` with workspace-backed inputs
+(all at fixed addresses).  Before each replay the caller updates the input
+buffer content in-place so the graph sees fresh data at the same tensor
+addresses.
+
+Only the model forward is captured — sampling runs outside the graph
+(via ``torch.multinomial`` which consumes a mutable RNG state).
+"""
+
+import torch
+from torch import Tensor
+
+
+class CudaGraphContext:
+    """CUDA-graph capture/replay for decode steps.
+
+    Parameters:
+        enabled: When ``False``, ``forward()`` always runs the live model
+            forward without capture/replay (graphs are cleared).  Toggle at
+            runtime via the ``set_enabled()`` method.
+
+    Usage::
+
+        gctx = CudaGraphContext()
+        with torch.inference_mode():
+            outputs = gctx.forward(
+                model,
+                key=(batch_size,),
+                input_ids=workspace.input_ids[:b].unsqueeze(1),
+                input_mask=input_mask,
+                kv_cache=kv_cache,
+                position_ids=workspace.position_ids[:b].unsqueeze(1),
+            )
+
+    The first call at a given key runs *without* capture (warmup).  The
+    second call captures the graph.  Subsequent calls replay the captured
+    graph.  A ``torch.cuda.synchronize()`` before capture drains in-flight
+    work so the graph trace is clean.
+    """
+
+    def __init__(self, enabled: bool = False):
+        self._enabled = enabled
+        self._graphs: dict[tuple, torch.cuda.CUDAGraph] = {}
+        self._outputs: dict[tuple, dict[str, Tensor]] = {}
+        self._warmed: set[tuple] = set()
+
+    @property
+    def enabled(self) -> bool:
+        return self._enabled
+
+    def set_enabled(self, flag: bool):
+        """Enable or disable CUDA-graph capture at runtime.
+
+        Disabling clears all captured graphs (frees GPU memory) and warmup
+        state.  Re-enabling after disable starts fresh — graphs are
+        re-captured on the next warmup cycle.
+        """
+        if flag == self._enabled:
+            return
+        self._enabled = flag
+        if not flag:
+            self._graphs.clear()
+            self._outputs.clear()
+            self._warmed.clear()
+
+    def forward(self, model, *, key, **kwargs) -> dict[str, Tensor]:
+        """Run ``model(**kwargs)`` via graph replay or live forward.
+
+        Args:
+            model: callable, e.g. ``self.model.forward``.
+            key: ``(batch_size,)`` — the dispatch key (one graph per batch size).
+            **kwargs: arguments forwarded to ``model``.  All tensor arguments
+                must reside at stable addresses (workspace buffers).
+
+        Returns:
+            The dict produced by ``model(**kwargs)``, e.g.
+            ``{"logits": ..., "h0": ...}``.
+        """
+        if not self._enabled:
+            self._outputs[key] = model(**kwargs)
+            return self._outputs[key]
+
+        if key in self._graphs:
+            self._graphs[key].replay()
+        elif key in self._warmed:
+            cap_output = model(**kwargs)
+            torch.cuda.synchronize()
+            graph = torch.cuda.CUDAGraph()
+            with torch.cuda.graph(graph):
+                self._outputs[key] = model(**kwargs)
+            self._graphs[key] = graph
+            self._warmed.discard(key)
+            return cap_output
+        else:
+            self._warmed.add(key)
+            self._outputs[key] = model(**kwargs)
+        return self._outputs[key]
+
+    def has_graph(self, key: tuple) -> bool:
+        return key in self._graphs

astrai/inference/runtime/sample.py

@@ -263,6 +263,12 @@ class SamplingPipeline(BaseSamplingStrategy):
             logits = strategy.apply(logits, filter_value, input_ids, input_mask)
         return logits
 
+    @staticmethod
+    def _is_greedy(temperature: Union[float, Tensor]) -> bool:
+        if isinstance(temperature, Tensor):
+            return bool((temperature == 0).all())
+        return temperature == 0
+
     @torch.inference_mode()
     def sample(
         self,
@@ -270,23 +276,52 @@ class SamplingPipeline(BaseSamplingStrategy):
         filter_value: float = -float("inf"),
         input_ids: Optional[Tensor] = None,
         input_mask: Optional[Tensor] = None,
-    ) -> Tensor:
+        return_logprobs: bool = False,
+    ):
         """Apply strategies then sample (softmax + multinomial).
 
+        Short-circuits to ``argmax`` when temperature is exactly 0
+        (deterministic / greedy decode).
+
         Args:
             logits: Raw logits ``[batch, vocab_size]``.
             input_ids: Previously generated token IDs ``[batch, seq_len]``.
             input_mask: Boolean mask for ``input_ids`` padding.
+            return_logprobs: If ``True``, return ``(tokens, logprobs)``
+                where ``logprobs[i]`` is the log-probability of
+                ``tokens[i]`` under the (post-strategy) sampling
+                distribution.
 
         Returns:
-            Sampled token IDs ``[batch]``.
+            Sampled token IDs ``[batch]``, or — when ``return_logprobs``
+            is ``True`` — a ``(token_ids, chosen_logprobs)`` tuple.
         """
-        return torch.multinomial(
-            torch.softmax(
-                self.apply(logits, filter_value, input_ids, input_mask), dim=-1
-            ),
-            num_samples=1,
+        if self._is_greedy_pipeline():
+            tokens = logits.argmax(dim=-1)
+            if not return_logprobs:
+                return tokens
+            log_probs = torch.log_softmax(logits.float(), dim=-1)
+            chosen = torch.gather(log_probs, -1, tokens.unsqueeze(-1)).squeeze(-1)
+            return tokens, chosen
+
+        transformed = self.apply(logits, filter_value, input_ids, input_mask)
+        tokens = torch.multinomial(
+            torch.softmax(transformed, dim=-1), num_samples=1
         ).squeeze(-1)
+        if not return_logprobs:
+            return tokens
+        log_probs = torch.log_softmax(transformed.float(), dim=-1)
+        chosen = torch.gather(log_probs, -1, tokens.unsqueeze(-1)).squeeze(-1)
+        return tokens, chosen
+
+    def _is_greedy_pipeline(self) -> bool:
+        """True if the first strategy is greedy temperature (temp=0)."""
+        if not self.strategies:
+            return False
+        first = self.strategies[0]
+        return isinstance(first, TemperatureStrategy) and self._is_greedy(
+            first.temperature
+        )
 
 
 @torch.inference_mode()
@@ -299,10 +334,18 @@ def sample(
     input_ids: Optional[Tensor] = None,
     input_mask: Optional[Tensor] = None,
     filter_value: float = -float("inf"),
-) -> Tensor:
+    return_logprobs: bool = False,
+):
     """Apply sampling strategies then sample (softmax + multinomial).
 
-    Shortcut for ``SamplingPipeline(...).sample(logits)``.
+    Shortcut for ``SamplingPipeline(...).sample(logits, return_logprobs=)``.
+
+    When **temperature** is exactly 0 (scalar or single-element tensor)
+    the function short-circuits to ``argmax`` for deterministic decode.
+
+    When **frequency_penalty** is 0 (the common decode case), the entire
+    frequency penalty computation — including the O(batch * vocab) count
+    tensor allocation — is skipped.
 
     Args:
         logits: Raw logits ``[batch, vocab_size]``.
@@ -310,15 +353,34 @@ def sample(
             (0.0 disables, range -2.0~2.0).
         input_ids: Previously generated token IDs ``[batch, seq_len]``.
         input_mask: Boolean mask for ``input_ids`` padding.
+        return_logprobs: If ``True``, also return the log-probability
+            of each sampled token under the (post-strategy) sampling
+            distribution — useful for RL rollout (PPO/GRPO importance
+            ratios).
 
     Returns:
-        Sampled token IDs ``[batch]``.
+        Sampled token IDs ``[batch]``, or — when ``return_logprobs`` is
+        ``True`` — a ``(token_ids, chosen_logprobs)`` tuple where
+        ``chosen_logprobs`` has shape ``[batch]``.
     """
-    return SamplingPipeline(
-        [
-            TemperatureStrategy(temperature),
-            TopKStrategy(top_k),
-            TopPStrategy(top_p),
-            FrequencyPenaltyStrategy(frequency_penalty),
-        ]
-    ).sample(logits, filter_value, input_ids, input_mask)
+    has_freq = (
+        (isinstance(frequency_penalty, Tensor) and (frequency_penalty != 0).any())
+        if isinstance(frequency_penalty, Tensor)
+        else frequency_penalty != 0
+    )
+
+    strategies: List[BaseSamplingStrategy] = [
+        TemperatureStrategy(temperature),
+        TopKStrategy(top_k),
+        TopPStrategy(top_p),
+    ]
+    if has_freq:
+        strategies.append(FrequencyPenaltyStrategy(frequency_penalty))
+
+    return SamplingPipeline(strategies).sample(
+        logits,
+        filter_value=filter_value,
+        input_ids=input_ids,
+        input_mask=input_mask,
+        return_logprobs=return_logprobs,
+    )

astrai/inference/scheduler.py

@@ -0,0 +1,400 @@
+import logging
+import threading
+import uuid
+from contextlib import nullcontext
+from typing import Any, Dict, List, Optional, Tuple, Union
+
+import torch
+
+from astrai.extension import (
+    ATTN_BACKEND,
+    AttentionBackend,
+    attn_backend,
+    get_backend,
+)
+from astrai.inference.cache import PagePool, TaskCacheManager
+from astrai.inference.metrics import MetricsCollector
+from astrai.inference.runtime.executor import Executor
+from astrai.inference.task import STOP, Task, TaskManager, TaskStatus
+from astrai.model.automodel import AutoModel
+from astrai.tokenize.tokenizer import AutoTokenizer
+
+logger = logging.getLogger(__name__)
+
+
+class InferenceScheduler:
+    """Continuous batching loop: cleanup -> refill -> prefill -> decode (all groups)."""
+
+    def __init__(
+        self,
+        model: AutoModel,
+        tokenizer: AutoTokenizer,
+        max_batch_size: int = 16,
+        max_seq_len: Optional[int] = None,
+        device: Optional[str] = None,
+        dtype: Optional[torch.dtype] = None,
+        cache: Optional[PagePool] = None,
+        enable_cuda_graph: bool = True,
+        backend: Optional[Union[str, ATTN_BACKEND, AttentionBackend, type]] = None,
+    ):
+        config = model.config
+
+        if max_seq_len is not None:
+            self.max_seq_len = max_seq_len
+        elif config.max_position_embeddings is not None:
+            self.max_seq_len = config.max_position_embeddings
+        else:
+            raise ValueError(
+                "max_seq_len must be provided either as argument "
+                "or in model config (config.max_position_embeddings)"
+            )
+        self.device = device or next(model.parameters()).device
+        self.dtype = dtype or next(model.parameters()).dtype
+
+        head_dim = config.hidden_size // config.num_attention_heads
+
+        if cache is not None:
+            self._cache = cache
+        else:
+            self._cache = PagePool(
+                n_layers=config.num_hidden_layers,
+                n_kv_heads=config.num_key_value_heads,
+                head_dim=head_dim,
+                max_batch_size=max_batch_size,
+                max_seq_len=self.max_seq_len,
+                device=self.device,
+                dtype=self.dtype,
+            )
+
+        self._metrics = MetricsCollector()
+
+        self._task_cache = TaskCacheManager(self._cache)
+
+        self._task_mgr = TaskManager(
+            tokenizer=tokenizer,
+            max_batch_size=max_batch_size,
+            max_seq_len=self.max_seq_len,
+            metrics=self._metrics,
+        )
+
+        if backend is None:
+            self._backend = None
+            active_backend = get_backend()
+        else:
+            active_backend = backend
+        with attn_backend(active_backend):
+            if backend is not None:
+                self._backend = get_backend()
+            self._backend_name = type(get_backend()).__name__
+            self._executor = Executor(
+                model=model,
+                kv_cache=self._cache,
+                task_cache=self._task_cache,
+                device=self.device,
+                dtype=self.dtype,
+                enable_cuda_graph=enable_cuda_graph,
+            )
+
+        self._stop_event = threading.Event()
+        self._loop_thread: Optional[threading.Thread] = None
+
+    def add_task(self, prompt: str, **kwargs) -> str:
+        return self._task_mgr.add_task(prompt, **kwargs)
+
+    def remove_task(self, task_id: str):
+        for task in self._task_mgr.remove_task(task_id):
+            self._task_cache.task_free(task.task_id)
+
+    def get_stats(self) -> Dict[str, Any]:
+        return self._task_mgr.get_stats()
+
+    @property
+    def backend_name(self) -> str:
+        return self._backend_name
+
+    @property
+    def cuda_graph_enabled(self) -> bool:
+        return self._executor.cuda_graph_enabled
+
+    def _backend_context(self):
+        if self._backend is None:
+            return nullcontext()
+        return attn_backend(self._backend)
+
+    @staticmethod
+    def _task_backend_groups(tasks: List[Task]):
+        groups = {}
+        for task in tasks:
+            groups.setdefault(task.backend, (task.backend, []))[1].append(task)
+        return groups.values()
+
+    def _step(
+        self, tasks: List[Task], return_logprobs: bool = False
+    ) -> Tuple[List[Task], List[Task]]:
+        """Advance every active task by one token (prefill + decode).
+
+        Single shared primitive for both the continuous-batching loop and
+        the synchronous ``run_batch`` path, so the two cannot drift.
+
+        Tasks must already be allocated in the KV cache. Tasks without output
+        are prefilled first and sample their first token from the final prompt
+        position. Tasks with output extend the cache by one position and decode
+        from their latest generated token.
+
+        Args:
+            tasks: Active tasks to advance by one token.
+            return_logprobs: Forwarded to ``execute_decode``; per-token
+                logprobs are recorded on each task's ``output_logprobs``.
+
+        Returns:
+            ``(decoded, aborted)``: tasks that produced a new token (its ID
+            already appended to ``output_ids``) and tasks that hit the
+            sequence cap and were marked ``ABORTED``.
+        """
+        to_prefill = [t for t in tasks if not t.prefill_done and t.prompt_ids]
+        prefilled_ids = set()
+        produced: List[Task] = []
+        if to_prefill:
+            for t in to_prefill:
+                t.input_tokens = len(t.prompt_ids)
+
+            groups: Dict[Tuple[int, int, Optional[AttentionBackend]], List[Task]] = {}
+            for t in to_prefill:
+                start_pos = min(
+                    self._task_cache.task_cached(t.task_id), len(t.prompt_ids) - 1
+                )
+                groups.setdefault((len(t.prompt_ids), start_pos, t.backend), []).append(
+                    t
+                )
+
+            for (prompt_len, start_pos, _), group in groups.items():
+                backend = group[0].backend
+                backend_context = (
+                    attn_backend(backend) if backend is not None else nullcontext()
+                )
+                with (
+                    backend_context,
+                    self._metrics.record([t.task_id for t in group], "prefill"),
+                ):
+                    prefilled, step_out = self._executor.execute_prefill(
+                        group, prompt_len, start_pos, return_logprobs=return_logprobs
+                    )
+
+                for t, out in zip(prefilled, step_out):
+                    t.output_ids.append(out[0] if return_logprobs else out)
+                    t.output_tokens += 1
+                    t.mark_prefill_done()
+                    prefilled_ids.add(t.task_id)
+                    produced.append(t)
+
+                start_logical_page = start_pos // self._cache.page_size
+                for t in group:
+                    self._task_cache.task_record_hashes(
+                        t.task_id, t.prompt_ids, start_logical_page
+                    )
+
+        decoded: List[Task] = []
+        aborted: List[Task] = []
+        for t in tasks:
+            if t.task_id in prefilled_ids:
+                continue
+            if self._task_cache.task_extend(t.task_id, t.next_pos):
+                decoded.append(t)
+            else:
+                t.status = TaskStatus.ABORTED
+                aborted.append(t)
+
+        for backend, group in self._task_backend_groups(decoded):
+            backend_context = (
+                attn_backend(backend) if backend is not None else nullcontext()
+            )
+            with (
+                backend_context,
+                self._metrics.record([t.task_id for t in group], "decode"),
+            ):
+                step_out = self._executor.execute_decode(
+                    group, return_logprobs=return_logprobs
+                )
+            for t, out in zip(group, step_out):
+                t.output_ids.append(out[0] if return_logprobs else out)
+                t.output_tokens += 1
+                t.advance_kv()
+                produced.append(t)
+
+        return produced, aborted
+
+    def _run_generation_loop(self):
+        stop_ids = self._task_mgr.tokenizer.stop_ids
+        try:
+            with self._backend_context():
+                while not self._stop_event.is_set():
+                    finished = self._task_mgr.remove_finished_tasks(stop_ids)
+                    for task in finished:
+                        if task.status == TaskStatus.FINISHED:
+                            self._task_cache.task_record_hashes(
+                                task.task_id,
+                                self._task_cache.task_cacheable_ids(
+                                    task.task_id, task.prompt_ids, task.output_ids
+                                ),
+                            )
+                        self._task_cache.task_free(task.task_id)
+
+                    active = self._task_mgr.get_active_tasks()
+                    available = self._task_mgr.max_batch_size - len(active)
+                    if available > 0:
+                        candidates = self._task_mgr.pull_candidates(available)
+                        failed = []
+                        for task in candidates:
+                            if self._task_cache.task_alloc(
+                                task.task_id, task.prompt_ids
+                            ):
+                                self._task_mgr.activate(task)
+                            else:
+                                failed.append(task)
+                        if failed:
+                            self._task_mgr.return_to_waiting(failed)
+
+                    if not self._task_mgr.has_work():
+                        self._task_mgr.wait_for_tasks(timeout=1.0)
+                        continue
+
+                    active = self._task_mgr.get_active_tasks()
+
+                    decoded, aborted = self._step(active)
+
+                    for t in aborted:
+                        self._task_mgr.invoke_callback(t.task_id, STOP)
+
+                    for t in decoded:
+                        new_text = t.decode_new_token(self._task_mgr.tokenizer)
+                        if new_text:
+                            self._task_mgr.invoke_callback(t.task_id, new_text)
+                        if t.is_finished(stop_ids):
+                            self._task_mgr.invoke_callback(t.task_id, STOP)
+
+        except Exception as e:
+            self._stop_event.set()
+            logger.error(f"Scheduler loop crashed: {e}", exc_info=True)
+            self._abort_and_clear(free_waiting=False)
+
+    def start(self):
+        if self._loop_thread is not None and self._loop_thread.is_alive():
+            return
+        self._stop_event.clear()
+        t = threading.Thread(target=self._run_generation_loop, daemon=True)
+        t.start()
+        self._loop_thread = t
+
+    def stop(self):
+        self._stop_event.set()
+        self._task_mgr.wake()
+        if self._loop_thread is not None:
+            self._loop_thread.join(timeout=2.0)
+        self._loop_thread = None
+        self._abort_and_clear(free_waiting=True)
+        if torch.cuda.is_available():
+            torch.cuda.empty_cache()
+
+    def _abort_and_clear(self, free_waiting: bool):
+        """Invoke STOP callbacks, release cache slots, and clear task queues."""
+        for task in self._task_mgr.get_active_tasks():
+            self._task_mgr.invoke_callback(task.task_id, STOP)
+            self._task_cache.task_free(task.task_id)
+        for task in self._task_mgr.get_waiting_tasks():
+            self._task_mgr.invoke_callback(task.task_id, STOP)
+            if free_waiting:
+                self._task_cache.task_free(task.task_id)
+        self._task_mgr.clear_queues()
+
+    def run_batch(
+        self,
+        prompt_ids_list: List[List[int]],
+        *,
+        max_tokens: Optional[int] = None,
+        temperature: float = 1.0,
+        top_p: float = 1.0,
+        top_k: int = 50,
+        frequency_penalty: float = 0.0,
+        rep_window: int = 64,
+        return_logprobs: bool = False,
+    ) -> List[List[int]]:
+        """Synchronous batch generation without the scheduler thread.
+
+        Accepts already-tokenized prompts (no string round-trip) and runs
+        prefill + decode to completion on the calling thread.  Designed for
+        RL rollout, where logprobs of the behaviour policy must be collected
+        alongside generated tokens.
+
+        Args:
+            prompt_ids_list: ``B`` prompts, each a list of token IDs.
+            max_tokens: Maximum tokens to generate per prompt.  ``None``
+                uses ``self.max_seq_len - len(prompt_ids)``.
+            temperature/top_p/top_k/frequency_penalty/rep_window: Sampling
+                parameters (uniform across the batch).
+            return_logprobs: If ``True``, return ``(token_ids, logprobs)``
+                tuples per prompt (logprobs aligned 1-to-1 with token_ids).
+
+        Returns:
+            ``List[List[int]]`` of generated token IDs per prompt, or —
+            when ``return_logprobs`` is ``True`` —
+            ``List[Tuple[List[int], List[float]]]``.
+        """
+        stop_ids = self._task_mgr.tokenizer.stop_ids
+        seq_cap = self.max_seq_len
+        request_backend = get_backend(use_default=False)
+
+        tasks: List[Task] = []
+        for ids in prompt_ids_list:
+            if len(ids) >= seq_cap:
+                tasks.append(None)
+                continue
+            t_max = max_tokens
+            if t_max is None:
+                t_max = seq_cap - len(ids)
+            else:
+                t_max = min(t_max, seq_cap - len(ids))
+            if t_max <= 0:
+                tasks.append(None)
+                continue
+            task = Task(
+                task_id=f"batch_{uuid.uuid4().hex[:8]}",
+                prompt_ids=list(ids),
+                max_tokens=t_max,
+                temperature=temperature,
+                top_p=top_p,
+                top_k=top_k,
+                frequency_penalty=frequency_penalty,
+                rep_window=rep_window,
+                backend=request_backend,
+            )
+            if not self._task_cache.task_alloc(task.task_id, task.prompt_ids):
+                tasks.append(None)
+                continue
+            task.input_tokens = len(task.prompt_ids)
+            self._metrics.register(task.task_id)
+            tasks.append(task)
+
+        try:
+            live = [t for t in tasks if t is not None]
+
+            with self._backend_context():
+                while live:
+                    decoded, _ = self._step(live, return_logprobs=return_logprobs)
+                    live = [t for t in decoded if not t.is_finished(stop_ids)]
+        finally:
+            for t in tasks:
+                if t is not None:
+                    self._metrics.mark_finished(
+                        t.task_id, t.input_tokens, t.output_tokens
+                    )
+                    self._task_cache.task_free(t.task_id)
+
+        results: List[Any] = []
+        for t in tasks:
+            if t is None:
+                results.append(([], []) if return_logprobs else [])
+            elif return_logprobs:
+                results.append((list(t.output_ids), list(t.output_logprobs)))
+            else:
+                results.append(list(t.output_ids))
+        return results

astrai/inference/task.py

@@ -1,18 +1,48 @@
-import logging
 import threading
 import time
 import uuid
 from collections import deque
 from enum import Enum
-from typing import Any, Callable, Deque, Dict, List, Optional
+from typing import TYPE_CHECKING, Any, Callable, Deque, Dict, List, Optional
 
+from tokenizers.decoders import DecodeStream
+
+from astrai.inference.metrics import MetricsCollector
 from astrai.tokenize.tokenizer import AutoTokenizer
 
-logger = logging.getLogger(__name__)
+if TYPE_CHECKING:
+    from astrai.extension import AttentionBackend
 
 STOP = object()
 
 
+class StreamDecoder:
+    """Incremental decoder backed by the tokenizers library's DecodeStream.
+
+    Delegates to the Rust-native streaming decoder which maintains an
+    O(1) bounded token buffer internally (via prefix drain), avoiding
+    the O(n²) cost of re-decoding the full history on each step.
+
+    Multi-byte UTF-8 sequences split across token boundaries are
+    buffered until complete; ``push`` returns "" while the trailing
+    sequence is still incomplete.
+    """
+
+    __slots__ = ("_stream", "_tok")
+
+    def __init__(self, tokenizer: AutoTokenizer):
+        self._tok = tokenizer._tokenizer
+        self._stream = DecodeStream(skip_special_tokens=True)
+
+    def push(self, token_id: int) -> str:
+        """Append a token ID and return newly completed text.
+
+        Returns "" while a multi-byte character is still incomplete.
+        """
+        chunk = self._stream.step(self._tok, token_id)
+        return chunk or ""
+
+
 class TaskStatus(Enum):
     """Task lifecycle states."""
 
@@ -35,6 +65,7 @@ class Task:
         top_k: int = 50,
         frequency_penalty: float = 0.0,
         rep_window: int = 64,
+        backend: Optional["AttentionBackend"] = None,
     ):
         self.task_id = task_id
         self.prompt_ids = prompt_ids
@@ -44,17 +75,44 @@ class Task:
         self.top_k = top_k
         self.frequency_penalty = frequency_penalty
         self.rep_window = rep_window
+        self.backend = backend
 
         self.status = TaskStatus.PENDING
         self.output_ids: List[int] = []
+        self.output_logprobs: List[float] = []
         self.input_tokens: int = 0
         self.output_tokens: int = 0
-        self.arrival_time = time.time()
-        self.finish_time: Optional[float] = None
+        self._kv_len: int = 0
+        self._decoder: Optional[StreamDecoder] = None
+
+    def mark_prefill_done(self):
+        """Prompt KV is materialized by prefill; first output sampled but
+        not yet written to KV."""
+        self._kv_len = self.input_tokens
+
+    def advance_kv(self):
+        """One more position written to KV (after a decode forward)."""
+        self._kv_len += 1
+
+    def decode_new_token(self, tokenizer: AutoTokenizer) -> str:
+        """Decode the last appended output token, buffering incomplete
+        multi-byte sequences across calls.
+
+        Lazily creates a :class:`StreamDecoder` on first use.
+        """
+        if self._decoder is None:
+            self._decoder = StreamDecoder(tokenizer)
+        return self._decoder.push(self.output_ids[-1])
 
     @property
     def next_pos(self) -> int:
-        return self.input_tokens + len(self.output_ids)
+        """KV position where the next decode step will write."""
+        return self._kv_len
+
+    @property
+    def prefill_done(self) -> bool:
+        """True when all prompt KV entries are materialized."""
+        return self._kv_len >= self.input_tokens > 0
 
     def is_finished(self, stop_ids: List[int]) -> bool:
         if self.max_tokens is not None and self.output_tokens >= self.max_tokens:
@@ -72,12 +130,11 @@ class TaskManager:
         tokenizer: AutoTokenizer,
         max_batch_size: int = 16,
         max_seq_len: int = 8192,
-        max_prompt_len: int = 512,
+        metrics: Optional["MetricsCollector"] = None,
     ):
         self.tokenizer = tokenizer
         self.max_batch_size = max_batch_size
         self.max_seq_len = max_seq_len
-        self.max_prompt_len = max_prompt_len
 
         self.waiting_queue: Deque[Task] = deque()
         self.active_tasks: List[Task] = []
@@ -89,6 +146,8 @@ class TaskManager:
         self._total_tasks = 0
         self._total_tokens = 0
 
+        self._metrics = metrics
+
     def add_task(
         self,
         prompt: str,
@@ -98,17 +157,13 @@ class TaskManager:
         top_k: int = 50,
         frequency_penalty: float = 0.0,
         rep_window: int = 64,
+        backend: Optional["AttentionBackend"] = None,
         stream_callback: Optional[Callable[[str], None]] = None,
     ) -> str:
         task_id = f"task_{int(time.time())}_{uuid.uuid4().hex[:8]}"
         prompt_ids = self.tokenizer.encode(prompt)
-        if len(prompt_ids) > self.max_prompt_len:
-            prompt_ids = prompt_ids[-self.max_prompt_len :]
-
-        if len(prompt_ids) >= self.max_seq_len:
-            if stream_callback:
-                stream_callback(STOP)
-            return task_id
+        if len(prompt_ids) > self.max_seq_len:
+            prompt_ids = prompt_ids[-self.max_seq_len :]
 
         if max_tokens is None:
             max_tokens = self.max_seq_len - len(prompt_ids)
@@ -124,6 +179,7 @@ class TaskManager:
             top_k=top_k,
             frequency_penalty=frequency_penalty,
             rep_window=rep_window,
+            backend=backend,
         )
 
         with self._lock:
@@ -132,6 +188,9 @@ class TaskManager:
             if stream_callback:
                 self._callbacks[task_id] = stream_callback
 
+        if self._metrics is not None:
+            self._metrics.register(task_id)
+
         self._task_event.set()
         return task_id
 
@@ -151,26 +210,33 @@ class TaskManager:
             cb(token)
 
     def get_stats(self) -> Dict[str, Any]:
-        return {
+        stats: Dict[str, Any] = {
             "total_tasks": self._total_tasks,
             "total_tokens": self._total_tokens,
             "active_tasks": len(self.active_tasks),
             "waiting_queue": len(self.waiting_queue),
         }
+        if self._metrics is not None:
+            stats.update(self._metrics.get_stats())
+        return stats
 
     def remove_finished_tasks(self, stop_ids: List[int]) -> List[Task]:
         with self._lock:
             finished = []
             for task in self.active_tasks:
                 if task.status == TaskStatus.ABORTED:
-                    task.finish_time = time.time()
                     finished.append(task)
                 elif task.is_finished(stop_ids):
                     task.status = TaskStatus.FINISHED
-                    task.finish_time = time.time()
                     finished.append(task)
                     self._total_tokens += task.output_tokens
 
+            if self._metrics is not None:
+                for task in finished:
+                    self._metrics.mark_finished(
+                        task.task_id, task.input_tokens, task.output_tokens
+                    )
+
             self.active_tasks = [
                 t
                 for t in self.active_tasks

astrai/inference/workspace.py

@@ -0,0 +1,164 @@
+"""Pre-allocated buffers for the inference decode hot path.
+
+Mirrors FlashInfer / SGLang's global workspace pattern: all per-step tensors
+are allocated eagerly at init (nothing is lazy), so the decode step
+reads/writes fixed-address tensors with zero ``torch.empty`` calls during
+the hot loop — a prerequisite for CUDA-graph capture.
+"""
+
+import torch
+from torch import Tensor
+
+_MAX_SPLITS = 32
+Q_TILE_ROWS = 64
+
+
+class InferenceWorkspace:
+    """Reusable fixed-shape per-step buffers for decode.
+
+    Families of buffers, all sized to ``max_batch_size`` / ``max_seq_len``
+    and sliced via views each step:
+
+    - ``decode_mask``: a ``[B, 1, total_len]`` validity mask, the RHS
+      ``arange`` pre-computed so only a single ``torch.ge(out=)`` runs per
+      step.
+    - ``input_ids``: per-step token IDs filled from host (pinned, double-
+      buffered so an in-flight async H2D copy never races the next fill).
+    - KV-cache bind metadata (``req_pool_indices``, ``seq_lens``,
+      ``kv_indptr``, ``inc``, ``out_cache_loc``), written by
+      ``PagePool.bind_tasks`` when the Executor passes this workspace.
+    - ``decode_o_part`` / ``decode_ml_part``: split-KV partial result buffers
+      (mirrors FlashInfer's workspace).  One global alloc, reused by every
+      decode step across all layers.  Sliced views are passed to the CUDA
+      attention kernel so its internal ``torch.empty`` hot-path alloc goes
+      through a stable address (CUDA-graph capturable).
+
+    No re-allocation while the server's bounds are respected.
+    """
+
+    def __init__(
+        self,
+        max_batch_size: int,
+        max_seq_len: int,
+        max_q_heads: int,
+        head_dim: int,
+        device: torch.device,
+        dtype: torch.dtype,
+    ):
+        self.max_batch_size = max_batch_size
+        self.max_seq_len = max_seq_len
+        self.max_q_heads = max_q_heads
+        self.head_dim = head_dim
+        self.device = device
+        self.dtype = dtype
+
+        # ``position_ids[:, None, None] >= arange`` RHS, reused every step.
+        self.arange = torch.arange(max_seq_len, device=device)
+        # Decode validity mask: [max_batch, 1, max_seq_len] bool.
+        self.input_mask = torch.empty(
+            (max_batch_size, 1, max_seq_len), dtype=torch.bool, device=device
+        )
+
+        # Per-step token IDs.  Values come from host Python lists every
+        # step, so the device buffer is pre-allocated (stable address for
+        # CUDA-graph capture) and filled via a host staging buffer.  A
+        # double buffer keeps a copy in flight from being overwritten by
+        # the next fill.
+        self.input_ids = torch.empty((max_batch_size,), dtype=torch.long, device=device)
+        self._pin = [
+            torch.empty((max_batch_size,), dtype=torch.long),
+            torch.empty((max_batch_size,), dtype=torch.long),
+        ]
+        self._pin_idx = 0
+
+        # KV-cache bind metadata (fixed shape, written by ``PagePool.bind_tasks``
+        # when the Executor passes this workspace).  Stable addresses make the
+        # decode forward CUDA-graph capturable.
+        self.req_pool_indices = torch.empty(
+            (max_batch_size,), dtype=torch.int32, device=device
+        )
+        self.seq_lens = torch.empty((max_batch_size,), dtype=torch.long, device=device)
+        self.kv_indptr = torch.empty(
+            (max_batch_size + 1,), dtype=torch.int32, device=device
+        )
+        self.qo_indptr = torch.empty(
+            (max_batch_size + 1,), dtype=torch.int32, device=device
+        )
+        max_q_tiles = max_batch_size * ((max_seq_len + Q_TILE_ROWS - 1) // Q_TILE_ROWS)
+        self.q_tile_to_batch = torch.empty(
+            (max_q_tiles,), dtype=torch.int32, device=device
+        )
+        self.q_tile_to_index = torch.empty(
+            (max_q_tiles,), dtype=torch.int32, device=device
+        )
+        self.inc = torch.arange(max_batch_size + 1, dtype=torch.int32, device=device)
+        self.out_cache_loc = torch.empty(
+            (max_batch_size, 1), dtype=torch.int32, device=device
+        )
+
+        # Per-step position IDs (must be at a fixed address for CUDA-graph capture).
+        self.position_ids = torch.empty(
+            (max_batch_size,), dtype=torch.long, device=device
+        )
+
+        # Split-KV partial-result buffers for decode (persistent, one global
+        # alloc per process — mirrors FlashInfer's workspace pattern).
+        # Shape: [max_batch_size, max_q_heads, _MAX_SPLITS, head_dim] (o_part)
+        #        [max_batch_size, max_q_heads, _MAX_SPLITS, 2]     (ml_part)
+        self.decode_o_part = torch.empty(
+            (max_batch_size, max_q_heads, _MAX_SPLITS, head_dim),
+            dtype=torch.float32,
+            device=device,
+        )
+        self.decode_ml_part = torch.empty(
+            (max_batch_size, max_q_heads, _MAX_SPLITS, 2),
+            dtype=torch.float32,
+            device=device,
+        )
+
+        # Decode output buffer (graph-safe pre-alloc).  Shape matches the
+        # decode kernel's output: [batch, q_head, head_dim].
+        self.decode_out = torch.empty(
+            (max_batch_size, max_q_heads, head_dim),
+            dtype=dtype,
+            device=device,
+        )
+
+    def fill_input_ids(self, ids: "list[int]") -> Tensor:
+        """Write ``ids`` into the device buffer and return ``[B]``.
+
+        Host values are staged through the double buffer and copied into the
+        stable device buffer (``copy_`` without pinning is synchronous, so
+        the alternating buffers guard against an in-flight transfer).
+        """
+        b = len(ids)
+        pin = self._pin[self._pin_idx]
+        self._pin_idx ^= 1
+        for i, v in enumerate(ids):
+            pin[i] = v
+        self.input_ids[:b].copy_(pin[:b])
+        return self.input_ids[:b]
+
+    def fill_input_ids_from_device(self, tokens: Tensor) -> Tensor:
+        """Copy device-resident ``[B]`` token ids into the device buffer.
+
+        Steady-state decode fast path: when the executor's cached task
+        signature still matches, the previous step's sampled tokens map
+        1:1 onto the current slots, so the ids transfer device-to-device
+        instead of round-tripping through the host staging buffers.
+        """
+        b = tokens.size(0)
+        self.input_ids[:b].copy_(tokens)
+        return self.input_ids[:b]
+
+    def decode_mask(self, position_ids: Tensor, total_len: int) -> Tensor:
+        """Return the ``[B, 1, total_len]`` validity mask for this step.
+
+        Written into the pre-allocated buffer via ``torch.ge(out=)`` — no
+        new tensor is allocated.  ``position_ids`` is the current step's
+        ``[B]`` positions; ``total_len`` must not exceed ``max_seq_len``.
+        """
+        b = position_ids.size(0)
+        out = self.input_mask[:b, :, :total_len]
+        torch.ge(position_ids[:, None, None], self.arange[:total_len], out=out)
+        return out

astrai/logging.py

@@ -0,0 +1,37 @@
+import logging
+import os
+
+from astrai.parallel.setup import get_rank, get_world_size
+
+
+class _DistributedContextFilter(logging.Filter):
+    def filter(self, record: logging.LogRecord) -> bool:
+        record.rank = str(get_rank())
+        record.world_size = str(get_world_size())
+        return True
+
+
+def setup_logging(level: str = "INFO"):
+    """Attach a StreamHandler to the ``astrai`` logger (idempotent).
+
+    Call once per process at the top of CLI scripts.
+    Set ``ASTR_LOG_LEVEL`` env var to override the default level.
+
+    Level names: ``DEBUG``, ``INFO``, ``WARNING``, ``ERROR``, ``CRITICAL``.
+    ``DEBUG`` enables per-step prefill/decode timing logs
+    (:func:`astrai.inference.runtime.executor.timed`).
+    """
+    logger = logging.getLogger("astrai")
+    if logger.handlers:
+        return
+    level_name = os.environ.get("ASTR_LOG_LEVEL", level).upper()
+    logger.setLevel(getattr(logging, level_name, logging.INFO))
+    handler = logging.StreamHandler()
+    handler.addFilter(_DistributedContextFilter())
+    handler.setFormatter(
+        logging.Formatter(
+            "%(asctime)s | %(levelname)-8s | rank=%(rank)2s/%(world_size)-2s | %(name)-32s | %(message)s",
+            datefmt="%Y-%m-%d %H:%M:%S",
+        )
+    )
+    logger.addHandler(handler)

astrai/model/__init__.py

@@ -9,7 +9,7 @@ from astrai.model.components.lora import (
     merge_lora,
     save_lora,
 )
-from astrai.model.components.mlp import MLP
+from astrai.model.components.mlp import MLP, DeepSeekMoE
 from astrai.model.components.norm import RMSNorm
 from astrai.model.encoder import EmbeddingEncoder
 from astrai.model.transformer import AutoRegressiveLM
@@ -19,6 +19,7 @@ __all__ = [
     "Linear",
     "RMSNorm",
     "MLP",
+    "DeepSeekMoE",
     "GQA",
     "DecoderBlock",
     # Models

astrai/model/automodel.py

@@ -4,13 +4,21 @@ AutoModel base class for model loading and saving.
 
 from contextlib import contextmanager
 from pathlib import Path
-from typing import Self, Union
+from typing import Union
 
 import torch.nn as nn
 
 from astrai.config.model_config import BaseModelConfig, ConfigFactory
 from astrai.factory import BaseFactory
-from astrai.serialization import load_model_config, load_model_weights, save_model
+from astrai.serialization import (
+    HF_MODEL_TYPES,
+    adapt_config,
+    convert_hf_weights,
+    load_model_config,
+    load_model_weights,
+    looks_like_hf_state_dict,
+    save_model,
+)
 
 
 @contextmanager
@@ -40,11 +48,12 @@ def _disable_random_init(enable: bool = True):
             setattr(nn.init, n, fn)
 
 
-class AutoModel(BaseFactory["AutoModel"], nn.Module):
-    """
-    Autoregressive language model base class.
-    Provides model loading/saving, registration, and generation.
-    """
+class ModelFactory(BaseFactory[nn.Module]):
+    """Pure factory for model dispatch, separated from nn.Module state."""
+
+
+class AutoModel(nn.Module):
+    """Model base class with loading/saving and generation."""
 
     def __init__(self, config: BaseModelConfig):
         super().__init__()
@@ -56,7 +65,25 @@ class AutoModel(BaseFactory["AutoModel"], nn.Module):
         path: Union[str, Path],
         disable_random_init: bool = True,
         strict: bool = True,
+        weights_format: str = "auto",
     ) -> nn.Module:
+        """Load a model directory.
+
+        Args:
+            path: Directory containing ``config.json`` and optionally
+                ``model.safetensors``.
+            disable_random_init: Replace parameter initializers with no-ops
+                while building the model.
+            strict: Passed to ``load_state_dict``.
+            weights_format: ``"auto"`` detects HuggingFace checkpoints
+                (LLaMA-style keys and ``model_type``) and converts them;
+                ``"astrai"`` skips conversion; ``"hf"`` forces it.
+        """
+        if weights_format not in ("auto", "astrai", "hf"):
+            raise ValueError(
+                f"weights_format must be one of 'auto', 'astrai', 'hf', "
+                f"got {weights_format!r}"
+            )
 
         model_path = Path(path)
 
@@ -65,17 +92,29 @@ class AutoModel(BaseFactory["AutoModel"], nn.Module):
             raise FileNotFoundError(f"Config file not found: {config_path}")
 
         raw = load_model_config(str(model_path))
+        is_hf_config = weights_format == "hf" or (
+            weights_format == "auto" and raw.get("model_type") in HF_MODEL_TYPES
+        )
+        if is_hf_config:
+            raw = adapt_config(raw)
+
         config = ConfigFactory.load(raw)
         model_type = config.model_type or "autoregressive_lm"
 
-        actual_cls = AutoModel.get_component_class(model_type)
+        actual_cls = ModelFactory.get_component_class(model_type)
 
         with _disable_random_init(enable=disable_random_init):
             model = actual_cls(config)
 
         weights_path = model_path / "model.safetensors"
-        if weights_path.exists():
+        index_path = model_path / "model.safetensors.index.json"
+        if weights_path.exists() or index_path.exists():
             state_dict = load_model_weights(str(model_path))
+            is_hf_weights = is_hf_config or (
+                weights_format == "auto" and looks_like_hf_state_dict(state_dict)
+            )
+            if is_hf_weights:
+                state_dict = convert_hf_weights(state_dict, config)
             model.load_state_dict(state_dict, strict=strict)
 
         return model
@@ -89,7 +128,3 @@ class AutoModel(BaseFactory["AutoModel"], nn.Module):
             state_dict=self.state_dict(),
             save_directory=str(save_directory),
         )
-
-    def to(self, *args, **kwargs) -> Self:
-        """Move model to device/dtype."""
-        return super().to(*args, **kwargs)

astrai/model/components/__init__.py

@@ -1,12 +1,12 @@
-from astrai.model.components.attention import GQA, MLA, repeat_kv
+from astrai.extension.backend.rotary import apply_rotary_emb
+from astrai.model.components.attention import GQA, MLA
 from astrai.model.components.decoder_block import DecoderBlock
 from astrai.model.components.embedding import Embedding
 from astrai.model.components.linear import Linear
-from astrai.model.components.mlp import MLP
+from astrai.model.components.mlp import MLP, DeepSeekMoE
 from astrai.model.components.norm import RMSNorm
 from astrai.model.components.rope import (
     RotaryEmbedding,
-    apply_rotary_emb,
     get_rotary_emb,
 )
 
@@ -14,6 +14,7 @@ __all__ = [
     "Linear",
     "RMSNorm",
     "MLP",
+    "DeepSeekMoE",
     "Embedding",
     "GQA",
     "MLA",
@@ -21,5 +22,4 @@ __all__ = [
     "RotaryEmbedding",
     "apply_rotary_emb",
     "get_rotary_emb",
-    "repeat_kv",
 ]

astrai/model/components/attention.py

@@ -5,22 +5,11 @@ import torch.nn as nn
 import torch.nn.functional as F
 from torch import Tensor
 
+from astrai.extension.backend import apply_rotary_emb, attention
 from astrai.factory import BaseFactory
-from astrai.inference.core.cache import CacheView
+from astrai.inference.cache import KVCache
 from astrai.model.components.linear import Linear
 from astrai.model.components.norm import RMSNorm
-from astrai.model.components.rope import apply_rotary_emb
-
-
-def repeat_kv(x: Tensor, n_rep: int) -> Tensor:
-    bs, slen, n_heads, head_dim = x.shape
-    if n_rep == 1:
-        return x
-    return (
-        x[:, :, :, None, :]
-        .expand(bs, slen, n_heads, n_rep, head_dim)
-        .reshape(bs, slen, n_heads * n_rep, head_dim)
-    )
 
 
 class AttnFactory(BaseFactory[nn.Module]):
@@ -66,19 +55,17 @@ class GQA(nn.Module):
             self.gate = Linear(dim, dim)
 
     def _split_heads(self, x: Tensor, n_heads) -> Tensor:
-        batch_size, seq_len, _ = x.shape
-        x = x.reshape(batch_size, seq_len, n_heads, self.head_dim)
-        return x
+        return x.reshape(*x.shape[:-1], n_heads, self.head_dim)
 
     def forward(
         self,
         x: Tensor,
         rotary_emb: Tensor,
         attn_mask: Tensor = None,
-        paged_cache: Optional[CacheView] = None,
+        kv_cache: Optional[KVCache] = None,
+        is_causal: bool = False,
+        fwd: Optional[str] = None,
     ) -> Tensor:
-        is_causal = attn_mask is None
-
         q = self._split_heads(self.q_proj(x), self.n_heads)
         k = self._split_heads(self.k_proj(x), self.n_kv_heads)
         v = self._split_heads(self.v_proj(x), self.n_kv_heads)
@@ -87,19 +74,9 @@ class GQA(nn.Module):
         if self.use_qk_norm:
             q, k = self.q_norm(q), self.k_norm(k)
 
-        if paged_cache is not None:
-            paged_cache.write(self.layer_id, k, v)
-            k, v = paged_cache.gather(self.layer_id)
-
-        k, v = repeat_kv(k, self.n_rep), repeat_kv(v, self.n_rep)
-
-        q, k, v = q.permute(0, 2, 1, 3), k.permute(0, 2, 1, 3), v.permute(0, 2, 1, 3)
-        sdqa_out = (
-            F.scaled_dot_product_attention(q, k, v, attn_mask, is_causal=is_causal)
-            .permute(0, 2, 1, 3)
-            .contiguous()
-            .flatten(2)
-        )
+        sdqa_out = attention(
+            q, k, v, kv_cache, self.layer_id, attn_mask, is_causal, fwd
+        ).reshape(*x.shape[:-1], self.dim)
 
         if self.use_gated_attention:
             sdqa_out = sdqa_out * F.sigmoid(self.gate(x))
@@ -162,19 +139,18 @@ class MLA(nn.Module):
         x: Tensor,
         rotary_emb: Tensor,
         attn_mask: Tensor = None,
-        paged_cache: Optional[CacheView] = None,
+        kv_cache: Optional[KVCache] = None,
+        is_causal: bool = False,
+        fwd: Optional[str] = None,
     ) -> Tensor:
-        bsz, seq_len, _ = x.size()
-        is_causal = attn_mask is None
-
         q = self.q_proj(x)
-        q = q.view(bsz, seq_len, self.n_heads, self.head_dim)
+        q = q.reshape(*x.shape[:-1], self.n_heads, self.head_dim)
 
         kv_compressed = self.kv_a_proj(x)
         kv_compressed = self.kv_norm(kv_compressed)
 
         kv = self.kv_b_proj(kv_compressed)
-        kv = kv.view(bsz, seq_len, self.n_kv_heads, -1)
+        kv = kv.reshape(*x.shape[:-1], self.n_kv_heads, -1)
 
         k_nope, k_rope, v = torch.split(
             kv, [self.qk_nope_head_dim, self.qk_rope_head_dim, self.head_dim], dim=-1
@@ -194,18 +170,9 @@ class MLA(nn.Module):
             q = self.q_norm(q)
             k = self.k_norm(k)
 
-        if paged_cache is not None:
-            paged_cache.write(self.layer_id, k, v)
-            k, v = paged_cache.gather(self.layer_id)
-
-        q = q.permute(0, 2, 1, 3)
-        k = k.permute(0, 2, 1, 3)
-        v = v.permute(0, 2, 1, 3)
-
-        attn_out = F.scaled_dot_product_attention(
-            q, k, v, attn_mask, is_causal=is_causal
-        )
-        attn_out = attn_out.permute(0, 2, 1, 3).contiguous().flatten(2)
+        attn_out = attention(
+            q, k, v, kv_cache, self.layer_id, attn_mask, is_causal, fwd
+        ).reshape(*x.shape[:-1], self.dim)
 
         if self.use_gated_attention:
             attn_out = attn_out * F.sigmoid(self.gate(x))

astrai/model/components/decoder_block.py

@@ -1,39 +1,76 @@
 from dataclasses import asdict
-from typing import Optional
+from typing import Optional, TypedDict
 
 import torch.nn as nn
 from torch import Tensor
 
-from astrai.inference.core.cache import CacheView
+from astrai.inference.cache import KVCache
 from astrai.model.components.attention import AttnFactory
-from astrai.model.components.mlp import FFNFactory
+from astrai.model.components.mlp import FFNFactory, RouterStats
 from astrai.model.components.norm import RMSNorm
 
 
+class DecoderOutput(TypedDict):
+    hidden_states: Tensor
+    aux_loss: Optional[Tensor]
+    router_stats: Optional[RouterStats]
+
+
 class DecoderBlock(nn.Module):
     def __init__(self, config, layer_id: int):
         super().__init__()
         cfg = asdict(config)
-        cfg["down_init_std"] = 0.02 / (2 * config.n_layers) ** 0.5
+        cfg.update(
+            dim=config.hidden_size,
+            dim_ffn=config.intermediate_size,
+            n_layers=config.num_hidden_layers,
+            n_heads=config.num_attention_heads,
+            n_kv_heads=config.num_key_value_heads,
+            norm_eps=config.rms_norm_eps,
+            down_init_std=0.02 / (2 * config.num_hidden_layers) ** 0.5,
+        )
         self.attention = AttnFactory.create(config.attn_type, **cfg, layer_id=layer_id)
-        self.input_norm = RMSNorm(config.dim, config.norm_eps)
-        self.post_attention_norm = RMSNorm(config.dim, config.norm_eps)
-        self.mlp = FFNFactory.create(config.ffn_type, **cfg)
+        self.input_norm = RMSNorm(config.hidden_size, config.rms_norm_eps)
+        self.post_attention_norm = RMSNorm(config.hidden_size, config.rms_norm_eps)
+        ffn_type = self._resolve_ffn_type(config, layer_id)
+        self.mlp = FFNFactory.create(ffn_type, **cfg)
+
+    @staticmethod
+    def _resolve_ffn_type(config, layer_id: int) -> str:
+        if config.ffn_type != "moe":
+            return config.ffn_type
+        mlp_only = config.mlp_only_layers or []
+        if layer_id in mlp_only:
+            return "mlp"
+        if config.decoder_sparse_step > 1:
+            if (layer_id + 1) % config.decoder_sparse_step != 0:
+                return "mlp"
+        return "moe"
 
     def forward(
         self,
         x: Tensor,
         rotary_emb: Tensor,
         attention_mask: Optional[Tensor] = None,
-        paged_cache: Optional[CacheView] = None,
-    ) -> Tensor:
+        kv_cache: Optional[KVCache] = None,
+        is_causal: bool = False,
+        fwd: Optional[str] = None,
+    ) -> DecoderOutput:
         attn_output = self.attention(
             self.input_norm(x),
             rotary_emb,
             attention_mask,
-            paged_cache,
+            kv_cache,
+            is_causal,
+            fwd,
         )
         x = attn_output + x
-        x = self.mlp(self.post_attention_norm(x)) + x
+        normalized = self.post_attention_norm(x)
+        mlp_output = self.mlp(normalized)
+        x = mlp_output["hidden_states"] + x
 
-        return x
+        return {
+            "hidden_states": x,
+            "aux_loss": mlp_output["aux_loss"],
+            "router_stats": mlp_output.get("router_stats"),
+        }

astrai/model/components/lora.py

@@ -1,11 +1,12 @@
 import logging
-from dataclasses import asdict, dataclass
+from dataclasses import asdict
 from pathlib import Path
 from typing import Optional, Set
 
 import torch
 import torch.nn as nn
 import torch.nn.functional as F
+from pydantic.dataclasses import dataclass
 
 from astrai.model.components.linear import Linear
 from astrai.serialization import (
@@ -39,8 +40,12 @@ class LoRALinear(nn.Module):
 
         self.r = r
         self.scaling = alpha / r
-        self.lora_A = nn.Parameter(torch.randn(r, self.weight.shape[1]) / r)
-        self.lora_B = nn.Parameter(torch.zeros(self.weight.shape[0], r))
+        device = self.weight.device
+        dtype = self.weight.dtype
+        lora_a = torch.randn(r, self.weight.shape[1], device=device, dtype=dtype) / r
+        lora_b = torch.zeros(self.weight.shape[0], r, device=device, dtype=dtype)
+        self.lora_A = nn.Parameter(lora_a)
+        self.lora_B = nn.Parameter(lora_b)
         self._merged = False
 
     def forward(self, x):

astrai/model/components/mlp.py

@@ -1,3 +1,5 @@
+from typing import Optional, TypedDict
+
 import torch
 import torch.nn as nn
 import torch.nn.functional as F
@@ -11,6 +13,22 @@ class FFNFactory(BaseFactory[nn.Module]):
     pass
 
 
+class RouterStats(TypedDict):
+    """Per-layer MoE routing statistics for training diagnostics.
+
+    Both tensors are detached monitoring data produced during forward.
+    """
+
+    probs: Tensor
+    topk_indices: Tensor
+
+
+class FFNOutput(TypedDict):
+    hidden_states: Tensor
+    aux_loss: Optional[Tensor]
+    router_stats: Optional[RouterStats]
+
+
 @FFNFactory.register("mlp")
 class MLP(nn.Module):
     def __init__(self, dim: int, dim_ffn: int, down_init_std: float = 0.02):
@@ -19,10 +37,10 @@ class MLP(nn.Module):
         self.gate = Linear(dim, dim_ffn)
         self.down = Linear(dim_ffn, dim, init_std=down_init_std)
 
-    def forward(self, x: Tensor) -> Tensor:
+    def forward(self, x: Tensor) -> FFNOutput:
         gated = self.up(x) * F.silu(self.gate(x))
         out = self.down(gated)
-        return out
+        return {"hidden_states": out, "aux_loss": None, "router_stats": None}
 
 
 @FFNFactory.register("moe")
@@ -36,6 +54,9 @@ class DeepSeekMoE(nn.Module):
         n_activated_experts: int = 2,
         topk_method: str = "greedy",
         n_layers: int = 1,
+        moe_intermediate_size: Optional[int] = None,
+        shared_expert_intermediate_size: Optional[int] = None,
+        norm_topk_prob: bool = True,
     ):
         super().__init__()
         self.dim = dim
@@ -43,6 +64,16 @@ class DeepSeekMoE(nn.Module):
         self.n_shared_experts = n_shared_experts
         self.n_activated_experts = n_activated_experts
         self.topk_method = topk_method
+        self.norm_topk_prob = norm_topk_prob
+
+        expert_dim_ffn = (
+            moe_intermediate_size if moe_intermediate_size is not None else dim_ffn
+        )
+        shared_dim_ffn = (
+            shared_expert_intermediate_size
+            if shared_expert_intermediate_size is not None
+            else dim_ffn
+        )
 
         self.router = Linear(dim, n_routed_experts, bias=False)
         moe_scale = 1 / max(n_shared_experts, 1) + 1 / n_activated_experts
@@ -50,51 +81,92 @@ class DeepSeekMoE(nn.Module):
 
         self.shared_experts = nn.ModuleList(
             [
-                MLP(dim, dim_ffn, down_init_std=down_init_std)
+                MLP(dim, shared_dim_ffn, down_init_std=down_init_std)
                 for _ in range(n_shared_experts)
             ]
         )
         self.routed_experts = nn.ModuleList(
             [
-                MLP(dim, dim_ffn, down_init_std=down_init_std)
+                MLP(dim, expert_dim_ffn, down_init_std=down_init_std)
                 for _ in range(n_routed_experts)
             ]
         )
 
-    def forward(self, x: Tensor) -> Tensor:
-        bsz, seq_len, dim = x.shape
+    def forward(self, x: Tensor) -> FFNOutput:
+        include_aux_loss = self.training and torch.is_grad_enabled()
+        shape = x.shape
+        dim = shape[-1]
         x_flat = x.view(-1, dim)
 
         shared_out = self._shared_forward(x_flat)
-        routed_out = self._routed_forward(x_flat)
+        routed_output = self._routed_forward(x_flat, include_aux_loss)
 
-        out = (shared_out + routed_out).view(bsz, seq_len, dim)
-        return out
+        out = (shared_out + routed_output["hidden_states"]).view(shape)
+        return {
+            "hidden_states": out,
+            "aux_loss": routed_output["aux_loss"],
+            "router_stats": routed_output["router_stats"],
+        }
 
     def _shared_forward(self, x: Tensor) -> Tensor:
         if self.n_shared_experts == 0:
             return torch.zeros_like(x)
-        return sum(e(x) for e in self.shared_experts) / self.n_shared_experts
+        return (
+            sum(e(x)["hidden_states"] for e in self.shared_experts)
+            / self.n_shared_experts
+        )
 
-    def _routed_forward(self, x: Tensor) -> Tensor:
+    def _routed_forward(self, x: Tensor, include_aux_loss: bool) -> FFNOutput:
         N, D = x.shape
         K = self.n_activated_experts
+        E = self.n_routed_experts
 
         router_logits = self.router(x)
         router_probs = torch.softmax(router_logits.float(), dim=-1).to(x.dtype)
 
-        topk_weights, topk_indices = torch.topk(router_probs, K, dim=-1)
-        topk_weights = topk_weights / topk_weights.sum(dim=-1, keepdim=True)
+        topk_weights, topk_indices = torch.topk(router_probs, K, dim=-1, sorted=False)
+        if self.norm_topk_prob:
+            topk_weights = topk_weights / topk_weights.sum(dim=-1, keepdim=True)
+
+        aux_loss = None
+        router_stats = None
+        if include_aux_loss:
+            expert_load = F.one_hot(topk_indices, num_classes=E).float()
+            expert_load = expert_load.mean(dim=(0, 1))
+            router_prob = router_probs.float().mean(dim=0)
+            aux_loss = E * (expert_load * router_prob).sum()
+            router_stats = {
+                "probs": router_probs.detach(),
+                "topk_indices": topk_indices,
+            }
+
+        # Grouped dispatch: sort (token, slot) pairs by expert so each expert
+        # consumes one contiguous slice instead of a per-expert mask scan.
+        flat_experts = topk_indices.reshape(-1)
+        sorted_experts, order = torch.sort(flat_experts)
+        flat_tokens = x.repeat_interleave(K, dim=0)[order]
+        flat_weights = topk_weights.reshape(-1, 1)[order]
+        boundaries = torch.cumsum(
+            torch.bincount(sorted_experts, minlength=E), dim=0
+        ).tolist()
 
         output = torch.zeros(N, D, device=x.device, dtype=x.dtype)
-        for expert_idx in range(self.n_routed_experts):
-            expert_mask = topk_indices == expert_idx
-            token_idx, k_idx = expert_mask.nonzero(as_tuple=True)
-            if token_idx.numel() == 0:
+        start = 0
+        for expert_idx, end in enumerate(boundaries):
+            if end == start:
                 continue
-            expert_input = x[token_idx]
-            expert_output = self.routed_experts[expert_idx](expert_input)
-            weights = topk_weights[token_idx, k_idx].unsqueeze(-1)
-            output.index_add_(0, token_idx, expert_output * weights)
+            expert_output = self.routed_experts[expert_idx](flat_tokens[start:end])[
+                "hidden_states"
+            ]
+            output.index_add_(
+                0,
+                order[start:end] // K,
+                expert_output * flat_weights[start:end],
+            )
+            start = end
 
-        return output
+        return {
+            "hidden_states": output,
+            "aux_loss": aux_loss,
+            "router_stats": router_stats,
+        }

astrai/model/components/rope.py

@@ -11,28 +11,23 @@ def get_rotary_emb(
     base: float = 10000,
     device: Optional[torch.device] = None,
 ) -> Tensor:
+    """Precompute cos/sin tables for rotary embedding.
+
+    Returns:
+        [max_len, dim/2, 2] (f32) — [cos, sin] pairs.
+    """
     theta = base ** (-torch.arange(0, dim, 2, dtype=torch.float64, device=device) / dim)
     t = torch.arange(0, max_len, dtype=torch.float64, device=device)
     freqs = torch.outer(t, theta).float()
     cos = torch.cos(freqs)
     sin = torch.sin(freqs)
-    return torch.complex(cos, sin)
+    return torch.stack([cos, sin], dim=-1)
 
 
 def ntk_base(base: float, dim: int, factor: float) -> float:
     return base * (factor ** (dim / (dim - 2)))
 
 
-def apply_rotary_emb(x: torch.Tensor, freqs_cis: Tensor) -> Tensor:
-    dtype = x.dtype
-    x_ = x.float().reshape(*x.shape[:-1], -1, 2)
-    x_complex = torch.view_as_complex(x_)
-    freqs_cis = freqs_cis.unsqueeze(2)
-    x_rotated = x_complex * freqs_cis
-    x_out = torch.view_as_real(x_rotated).flatten(-2)
-    return x_out.to(dtype)
-
-
 class RotaryEmbedding(nn.Module):
     def __init__(
         self,
@@ -56,16 +51,26 @@ class RotaryEmbedding(nn.Module):
         self._set_rotary_buffer(self.max_len)
 
     def _set_rotary_buffer(self, max_len: int):
-        rotary_emb = get_rotary_emb(self.dim, max_len, self.base)
-        freqs_cis = torch.view_as_real(rotary_emb)
+        freqs_cis = get_rotary_emb(self.dim, max_len, self.base)
         self.register_buffer("freqs_cis", freqs_cis, persistent=False)
 
     def forward(self, x: Tensor, position_ids: Optional[Tensor] = None) -> Tensor:
+        """Lookup cos/sin for the given positions.
+
+        Args:
+            x: [batch, seq_len, ...] — only batch and seq_len are used.
+            position_ids: [batch, seq_len] optional position indices.
+
+        Returns:
+            [batch, seq_len, dim/2, 2] (f32) — [cos, sin] pairs.
+        """
         if position_ids is None:
-            position_ids = (
-                torch.arange(x.size(1), device=x.device)
-                .unsqueeze(0)
-                .expand(x.size(0), -1)
-            )
-        position_freq_cis = self.freqs_cis[position_ids].float()
-        return torch.view_as_complex(position_freq_cis)
+            if x.ndim == 2:
+                position_ids = torch.arange(x.size(0), device=x.device)
+            else:
+                position_ids = (
+                    torch.arange(x.size(1), device=x.device)
+                    .unsqueeze(0)
+                    .expand(x.size(0), -1)
+                )
+        return self.freqs_cis[position_ids].float()

astrai/model/encoder.py

@@ -5,7 +5,7 @@ import torch.nn as nn
 from torch import Tensor
 
 from astrai.config.model_config import EncoderConfig
-from astrai.model.automodel import AutoModel
+from astrai.model.automodel import AutoModel, ModelFactory
 from astrai.model.components.decoder_block import DecoderBlock
 from astrai.model.components.embedding import Embedding
 from astrai.model.components.norm import RMSNorm
@@ -13,25 +13,33 @@ from astrai.model.components.rope import RotaryEmbedding
 from astrai.model.transformer import process_attention_mask
 
 
-@AutoModel.register("embedding")
+@ModelFactory.register("embedding")
 class EmbeddingEncoder(AutoModel):
     def __init__(self, config: EncoderConfig):
         super().__init__(config)
         self.config = config
-        rope_dim = config.dim // config.n_heads
+        rope_dim = config.hidden_size // config.num_attention_heads
         rope_base = config.rope_theta if config.rope_theta is not None else 10000
         self.rotary_embedding = RotaryEmbedding(
-            rope_dim, config.max_len, rope_base, rope_scaling=config.rope_scaling
+            rope_dim,
+            config.max_position_embeddings,
+            rope_base,
+            rope_scaling=config.rope_scaling,
         )
         self.embed_tokens = Embedding(
-            config.vocab_size, config.dim, neftune_alpha=config.neftune_alpha
+            config.vocab_size,
+            config.hidden_size,
+            neftune_alpha=config.neftune_alpha,
         )
 
         self.layers = nn.ModuleList(
-            [DecoderBlock(config, layer_id) for layer_id in range(config.n_layers)]
+            [
+                DecoderBlock(config, layer_id)
+                for layer_id in range(config.num_hidden_layers)
+            ]
         )
 
-        self.norm = RMSNorm(config.dim, config.norm_eps)
+        self.norm = RMSNorm(config.hidden_size, config.rms_norm_eps)
 
         self.pooling_type = config.pooling_type or "mean"
         self.normalize_embeddings = config.normalize_embeddings or False
@@ -59,10 +67,10 @@ class EmbeddingEncoder(AutoModel):
         x = self.embed_tokens(input_ids)
 
         rotary_emb = self.rotary_embedding(x, position_ids)
-        attn_mask = process_attention_mask(x, position_ids, input_mask, is_causal=False)
+        attn_mask = process_attention_mask(input_mask)
 
         for layer in self.layers:
-            x = layer(x, rotary_emb, attn_mask, paged_cache=None)
+            x = layer(x, rotary_emb, attn_mask)["hidden_states"]
 
         hidden_states = self.norm(x)
 

astrai/model/transformer.py

@@ -5,8 +5,8 @@ import torch.nn as nn
 from torch import Tensor
 
 from astrai.config.model_config import AutoRegressiveLMConfig
-from astrai.inference.core.cache import CacheView
-from astrai.model.automodel import AutoModel
+from astrai.inference.cache import KVCache
+from astrai.model.automodel import AutoModel, ModelFactory
 from astrai.model.components.decoder_block import DecoderBlock
 from astrai.model.components.embedding import Embedding
 from astrai.model.components.linear import Linear
@@ -15,35 +15,18 @@ from astrai.model.components.rope import RotaryEmbedding
 
 
 def process_attention_mask(
-    input_tensor: Tensor,
-    position_ids: Optional[Tensor],
-    input_mask: Optional[Tensor] = None,
-    is_causal: bool = False,
+    input_mask: Optional[Tensor],
 ) -> Optional[Tensor]:
-    if position_ids is None:
-        return None
-    if input_mask is not None and input_mask.dim() > 2:
-        return input_mask
-
-    device = input_tensor.device
-    B = input_tensor.size(0)
-    T = position_ids.max().item() + 1
-
     if input_mask is None:
-        if position_ids.min().item() == 0 and is_causal:
-            return None
-        attend = torch.ones(B, 1, T, dtype=torch.bool, device=device)
-    else:
-        attend = input_mask[:, :T].to(device=device, dtype=torch.bool).unsqueeze(1)
-
-    if is_causal:
-        causal = position_ids.unsqueeze(-1) >= torch.arange(T, device=device)
-        attend = attend & causal
-
-    return attend.unsqueeze(1)
+        return None
+    if input_mask.dim() == 2:
+        return input_mask[:, None, None, :]
+    if input_mask.dim() == 3:
+        return input_mask[:, None, :, :]
+    return input_mask
 
 
-@AutoModel.register("autoregressive_lm")
+@ModelFactory.register("autoregressive_lm")
 class AutoRegressiveLM(AutoModel):
     """Autoregressive language model with paged KV cache."""
 
@@ -53,24 +36,32 @@ class AutoRegressiveLM(AutoModel):
         rope_dim = (
             config.qk_rope_head_dim
             if config.attn_type == "mla"
-            else config.dim // config.n_heads
+            else config.hidden_size // config.num_attention_heads
         )
         rope_base = config.rope_theta if config.rope_theta is not None else 10000
         self.rotary_embedding = RotaryEmbedding(
-            rope_dim, config.max_len, rope_base, rope_scaling=config.rope_scaling
+            rope_dim,
+            config.max_position_embeddings,
+            rope_base,
+            rope_scaling=config.rope_scaling,
         )
         self.embed_tokens = Embedding(
-            config.vocab_size, config.dim, neftune_alpha=config.neftune_alpha
+            config.vocab_size,
+            config.hidden_size,
+            neftune_alpha=config.neftune_alpha,
         )
 
         self.layers = nn.ModuleList(
-            [DecoderBlock(config, layer_id) for layer_id in range(config.n_layers)]
+            [
+                DecoderBlock(config, layer_id)
+                for layer_id in range(config.num_hidden_layers)
+            ]
         )
 
-        self.norm = RMSNorm(config.dim, config.norm_eps)
-        self.lm_head = Linear(config.dim, config.vocab_size)
+        self.norm = RMSNorm(config.hidden_size, config.rms_norm_eps)
+        self.lm_head = Linear(config.hidden_size, config.vocab_size)
 
-        if self.config.tie_weight is True:
+        if self.config.tie_word_embeddings is True:
             self.lm_head.weight = self.embed_tokens.weight
 
         self.apply(self._init_weights)
@@ -85,7 +76,7 @@ class AutoRegressiveLM(AutoModel):
 
         state_dict = dict(state_dict)
 
-        if self.config.tie_weight is True:
+        if self.config.tie_word_embeddings is True:
             # same tensor for embed and lm_head
             if embed_key in state_dict:
                 state_dict[lm_head_key] = state_dict[embed_key]
@@ -101,7 +92,7 @@ class AutoRegressiveLM(AutoModel):
             destination=destination, prefix=prefix, keep_vars=keep_vars
         )
 
-        if self.config.tie_weight is True:
+        if self.config.tie_word_embeddings is True:
             lm_head_key = prefix + "lm_head.weight"
             if lm_head_key in state_dict:
                 del state_dict[lm_head_key]
@@ -112,19 +103,50 @@ class AutoRegressiveLM(AutoModel):
         self,
         input_ids: Tensor,
         input_mask: Optional[Tensor] = None,
-        paged_cache: Optional[CacheView] = None,
+        kv_cache: Optional[KVCache] = None,
         position_ids: Optional[Tensor] = None,
+        fwd: Optional[str] = None,
     ) -> Dict[str, Tensor]:
-        assert input_ids.ndim == 2
+        if fwd is None:
+            if input_ids.ndim != 2:
+                raise ValueError("training input_ids must be [batch, seq_len]")
+            if kv_cache is not None:
+                raise ValueError("training forward does not accept a KV cache")
+        elif fwd in ("prefill", "decode"):
+            if input_ids.ndim != 1:
+                raise ValueError("inference input_ids must be packed [tokens]")
+            if kv_cache is None:
+                raise ValueError("inference forward requires a KV cache")
+        else:
+            raise ValueError(f"unsupported forward mode: {fwd}")
 
         x = self.embed_tokens(input_ids)
         rotary_emb = self.rotary_embedding(x, position_ids)
-        attn_mask = process_attention_mask(x, position_ids, input_mask, is_causal=True)
+        attn_mask = process_attention_mask(input_mask)
+        use_sdpa_causal_mask = attn_mask is None
 
+        aux_losses = []
+        router_stats_list = []
         for layer in self.layers:
-            x = layer(x, rotary_emb, attn_mask, paged_cache)
+            layer_output = layer(
+                x,
+                rotary_emb,
+                attn_mask,
+                kv_cache,
+                use_sdpa_causal_mask,
+                fwd,
+            )
+            x = layer_output["hidden_states"]
+            stats = layer_output.get("router_stats")
+            if stats is not None:
+                aux_losses.append(layer_output["aux_loss"])
+                router_stats_list.append(stats)
 
         hidden_states = self.norm(x)
         logits = self.lm_head(hidden_states)
 
-        return {"logits": logits, "hidden_states": hidden_states}
+        output = {"logits": logits, "hidden_states": hidden_states}
+        if aux_losses:
+            output["aux_loss"] = torch.stack(aux_losses).mean()
+            output["router_stats"] = router_stats_list
+        return output

astrai/optim/__init__.py

@@ -0,0 +1,38 @@
+"""Optimizer implementations and factory registration."""
+
+from astrai.optim.composite import (
+    OptimizerFactory,
+    composite_state_dict,
+    composite_step,
+    composite_zero_grad,
+    refresh_param_groups,
+)
+from astrai.optim.mano_adamw import Mano, ManoAdamW
+from astrai.optim.muon_adamw import MuonAdamW
+from astrai.optim.nora_nadamw import (
+    NAdamW,
+    Nora,
+    NoraNAdamW,
+    OptimizerParameterGroups,
+    nora_direction,
+    nora_lr_scale,
+    partition_optimizer_parameters,
+)
+
+__all__ = [
+    "Mano",
+    "ManoAdamW",
+    "MuonAdamW",
+    "NAdamW",
+    "Nora",
+    "NoraNAdamW",
+    "OptimizerFactory",
+    "OptimizerParameterGroups",
+    "composite_state_dict",
+    "composite_step",
+    "composite_zero_grad",
+    "nora_direction",
+    "nora_lr_scale",
+    "partition_optimizer_parameters",
+    "refresh_param_groups",
+]

astrai/optim/composite.py

@@ -0,0 +1,71 @@
+"""Shared infrastructure for the optim package.
+
+This module hosts two things:
+
+* ``OptimizerFactory`` — the registry for built-in optimizers. Defining it
+  here (rather than in ``__init__.py``) lets each optimizer module import it
+  and register itself with a decorator, avoiding circular imports.
+* Composite-optimizer helpers — ``step``/``zero_grad``/``state_dict``/
+  ``param_groups`` delegation shared by every optimizer that routes different
+  parameter groups through distinct sub-optimizers.
+"""
+
+from typing import Any
+
+import torch
+from torch.optim import Optimizer
+
+from astrai.factory import BaseFactory
+
+
+class OptimizerFactory(BaseFactory[Optimizer]):
+    """Factory for built-in training optimizers."""
+
+
+def composite_step(
+    sub_optimizers: list[Optimizer],
+    closure=None,
+) -> torch.Tensor | None:
+    """Run ``step`` on every sub-optimizer, invoking the closure once.
+
+    The closure (if given) is executed inside ``torch.enable_grad`` exactly
+    once before any sub-optimizer steps, matching the contract of a single
+    ``Optimizer.step``. Sub-optimizers receive ``None`` so they do not
+    re-execute it.
+    """
+    loss = None
+    if closure is not None:
+        with torch.enable_grad():
+            loss = closure()
+    for sub in sub_optimizers:
+        sub.step()
+    return loss
+
+
+def composite_zero_grad(
+    sub_optimizers: list[Optimizer],
+    set_to_none: bool = True,
+) -> None:
+    for sub in sub_optimizers:
+        sub.zero_grad(set_to_none=set_to_none)
+
+
+def composite_state_dict(
+    named_sub_optimizers: dict[str, Optimizer | None],
+) -> dict[str, Any]:
+    """Serialize sub-optimizers, preserving ``None`` slots."""
+    return {
+        name: sub.state_dict() if sub is not None else None
+        for name, sub in named_sub_optimizers.items()
+    }
+
+
+def refresh_param_groups(
+    sub_optimizers: list[Optimizer],
+) -> list[dict]:
+    """Concatenate param_groups from every non-None sub-optimizer."""
+    groups: list[dict] = []
+    for sub in sub_optimizers:
+        if sub is not None:
+            groups.extend(sub.param_groups)
+    return groups

astrai/optim/mano_adamw.py

@@ -0,0 +1,214 @@
+"""Mano manifold optimizer combined with AdamW.
+
+Mano projects the momentum onto the tangent space of the Oblique manifold
+(axis-wise tangent projection) and normalizes it, replacing the expensive
+Newton-Schulz iteration in Muon with a cheaper manifold normalization.
+
+Reference: https://arxiv.org/abs/2601.23000
+"""
+
+import math
+
+import torch
+from torch import nn, optim
+from torch.optim import Optimizer
+
+from astrai.optim.composite import (
+    OptimizerFactory,
+    composite_state_dict,
+    composite_step,
+    composite_zero_grad,
+    refresh_param_groups,
+)
+from astrai.optim.nora_nadamw import partition_optimizer_parameters
+
+
+class Mano(Optimizer):
+    """Manifold Normalized Optimizer for two-dimensional matrices.
+
+    Each step alternates the projection axis (dim 0 / dim 1) to restrike the
+    manifold along both rows and columns. The tangent momentum is computed
+    without normalizing the parameter itself (v2 simplification) and the
+    epsilon is added (not clamped) to the norm denominator.
+    """
+
+    def __init__(
+        self,
+        params,
+        lr: float = 1e-3,
+        weight_decay: float = 0.1,
+        momentum: float = 0.95,
+        nesterov: bool = True,
+        eps: float = 1e-8,
+    ):
+        if lr < 0:
+            raise ValueError(f"Invalid learning rate: {lr}")
+        if weight_decay < 0:
+            raise ValueError(f"Invalid weight decay: {weight_decay}")
+        if not 0 <= momentum <= 1:
+            raise ValueError(f"Invalid momentum: {momentum}")
+        if eps <= 0:
+            raise ValueError(f"Invalid epsilon: {eps}")
+
+        defaults = {
+            "lr": lr,
+            "weight_decay": weight_decay,
+            "momentum": momentum,
+            "nesterov": nesterov,
+            "eps": eps,
+            "steps": 0,
+        }
+        super().__init__(params, defaults)
+        for group in self.param_groups:
+            for param in group["params"]:
+                if param.ndim != 2:
+                    raise ValueError(
+                        f"Mano only supports 2D matrices, got shape {tuple(param.shape)}"
+                    )
+
+    @torch.no_grad()
+    def step(self, closure=None):
+        loss = None
+        if closure is not None:
+            with torch.enable_grad():
+                loss = closure()
+
+        for group in self.param_groups:
+            lr = group["lr"]
+            weight_decay = group["weight_decay"]
+            momentum = group["momentum"]
+            nesterov = group["nesterov"]
+            eps = group["eps"]
+            dim = int(group["steps"] % 2)
+
+            for param in group["params"]:
+                if param.grad is None:
+                    continue
+                if param.grad.is_sparse:
+                    raise RuntimeError("Mano does not support sparse gradients")
+
+                grad = param.grad
+                state = self.state[param]
+                momentum_buffer = state.get("momentum_buffer")
+                if momentum_buffer is None:
+                    momentum_buffer = torch.zeros_like(grad)
+                momentum_buffer.mul_(momentum).add_(grad)
+                update = (
+                    grad.add(momentum_buffer, alpha=momentum)
+                    if nesterov
+                    else momentum_buffer
+                )
+
+                tangent = update - (
+                    torch.sum(update * param.data, dim=dim, keepdim=True) * param.data
+                )
+                direction = tangent / (
+                    torch.norm(tangent, p=2, dim=dim, keepdim=True) + eps
+                )
+
+                if weight_decay != 0:
+                    param.mul_(1 - lr * weight_decay)
+                adjusted_lr = lr * 0.2 * math.sqrt(direction.shape[dim])
+                param.add_(direction, alpha=-adjusted_lr)
+                state["momentum_buffer"] = momentum_buffer
+
+            group["steps"] += 1
+
+        return loss
+
+
+@OptimizerFactory.register("mano_adamw")
+class ManoAdamW(Optimizer):
+    """Mano for internal linear weights and AdamW for remaining parameters."""
+
+    optimizer_name = "mano_adamw"
+
+    def __init__(
+        self,
+        model: nn.Module,
+        lr: float = 3e-4,
+        weight_decay: float = 0.1,
+        momentum: float = 0.95,
+        nesterov: bool = True,
+    ):
+        groups = partition_optimizer_parameters(model)
+        all_params = [
+            *groups.nora,
+            *groups.nadamw_decay,
+            *groups.nadamw_no_decay,
+        ]
+        if not all_params:
+            raise ValueError(
+                "Cannot build an optimizer for a model with no trainable parameters"
+            )
+        super().__init__(all_params, {})
+
+        self.mano = (
+            Mano(
+                groups.nora,
+                lr=lr,
+                weight_decay=weight_decay,
+                momentum=momentum,
+                nesterov=nesterov,
+            )
+            if groups.nora
+            else None
+        )
+
+        adamw_groups = []
+        if groups.nadamw_decay:
+            adamw_groups.append(
+                {"params": groups.nadamw_decay, "weight_decay": weight_decay}
+            )
+        if groups.nadamw_no_decay:
+            adamw_groups.append({"params": groups.nadamw_no_decay, "weight_decay": 0.0})
+        self.adamw = (
+            optim.AdamW(
+                adamw_groups,
+                lr=lr,
+                betas=(0.9, 0.95),
+                fused=True,
+            )
+            if adamw_groups
+            else None
+        )
+        self.param_groups = refresh_param_groups([self.mano, self.adamw])
+
+    @torch.no_grad()
+    def step(self, closure=None):
+        return composite_step(
+            [opt for opt in (self.mano, self.adamw) if opt is not None],
+            closure,
+        )
+
+    def zero_grad(self, set_to_none: bool = True):
+        composite_zero_grad(
+            [opt for opt in (self.mano, self.adamw) if opt is not None],
+            set_to_none,
+        )
+
+    def state_dict(self) -> dict:
+        return composite_state_dict({"mano": self.mano, "adamw": self.adamw})
+
+    def load_state_dict(self, state_dict: dict):
+        if "muon" in state_dict or "nora" in state_dict:
+            raise ValueError(
+                "Checkpoint uses a different optimizer; select the matching "
+                "--optimizer to resume it"
+            )
+        if "mano" not in state_dict or "adamw" not in state_dict:
+            raise ValueError(
+                "Checkpoint optimizer state is not compatible with mano_adamw"
+            )
+
+        saved_mano = state_dict["mano"]
+        saved_adamw = state_dict["adamw"]
+        if (self.mano is None) != (saved_mano is None):
+            raise ValueError("Checkpoint Mano parameter groups do not match the model")
+        if (self.adamw is None) != (saved_adamw is None):
+            raise ValueError("Checkpoint AdamW parameter groups do not match the model")
+        if self.mano is not None:
+            self.mano.load_state_dict(saved_mano)
+        if self.adamw is not None:
+            self.adamw.load_state_dict(saved_adamw)
+        self.param_groups = refresh_param_groups([self.mano, self.adamw])

astrai/optim/muon_adamw.py

@@ -0,0 +1,95 @@
+"""Legacy Muon + AdamW combined optimizer."""
+
+from typing import Any
+
+import torch
+from torch import Tensor, nn, optim
+
+from astrai.optim.composite import (
+    OptimizerFactory,
+    composite_state_dict,
+    composite_step,
+    composite_zero_grad,
+    refresh_param_groups,
+)
+
+
+@OptimizerFactory.register("muon_adamw")
+class MuonAdamW(optim.Optimizer):
+    """Combined Muon (matrix) + AdamW (non-matrix) optimizer."""
+
+    optimizer_name = "muon_adamw"
+
+    def __init__(
+        self,
+        model: nn.Module,
+        lr: float = 3e-4,
+        weight_decay: float = 0.1,
+        momentum: float = 0.95,
+        nesterov: bool = True,
+        ns_steps: int = 5,
+        adjust_lr_fn: str = "match_rms_adamw",
+    ):
+        defaults = {
+            "lr": lr,
+            "weight_decay": weight_decay,
+            "momentum": momentum,
+            "nesterov": nesterov,
+            "ns_steps": ns_steps,
+            "adjust_lr_fn": adjust_lr_fn,
+        }
+        params = [param for param in model.parameters() if param.requires_grad]
+        super().__init__(params, defaults)
+
+        matrix_params: list[Tensor] = []
+        other_params: list[Tensor] = []
+        for name, param in model.named_parameters():
+            if not param.requires_grad:
+                continue
+            if (
+                param.dim() >= 2
+                and "norm" not in name
+                and "bias" not in name
+                and "embed" not in name
+                and "lm_head" not in name
+            ):
+                matrix_params.append(param)
+            else:
+                other_params.append(param)
+
+        self.muon = optim.Muon(
+            matrix_params,
+            lr=lr,
+            weight_decay=weight_decay,
+            momentum=momentum,
+            nesterov=nesterov,
+            ns_steps=ns_steps,
+            adjust_lr_fn=adjust_lr_fn,
+        )
+        self.adamw = optim.AdamW(
+            [{"params": other_params, "weight_decay": 0.0}],
+            lr=lr,
+            betas=(0.9, 0.95),
+            fused=True,
+        )
+
+        self.param_groups = refresh_param_groups([self.muon, self.adamw])
+
+    @torch.no_grad()
+    def step(self, closure=None):
+        return composite_step([self.muon, self.adamw], closure)
+
+    def zero_grad(self, set_to_none: bool = True):
+        composite_zero_grad([self.muon, self.adamw], set_to_none)
+
+    def state_dict(self) -> dict[str, Any]:
+        return composite_state_dict({"muon": self.muon, "adamw": self.adamw})
+
+    def load_state_dict(self, state_dict: dict[str, Any]):
+        if "muon" not in state_dict or "adamw" not in state_dict:
+            raise ValueError(
+                "Checkpoint optimizer state is not compatible with muon_adamw"
+            )
+        self.muon.load_state_dict(state_dict["muon"])
+        self.adamw.load_state_dict(state_dict["adamw"])
+        self.param_groups = refresh_param_groups([self.muon, self.adamw])

astrai/optim/nora_nadamw.py

@@ -0,0 +1,372 @@
+"""Nora matrix optimizer combined with Nesterov AdamW."""
+
+import math
+from dataclasses import dataclass
+from typing import Any
+
+import torch
+from torch import Tensor, nn
+from torch.distributed.tensor import DTensor, Shard
+from torch.optim import Optimizer
+
+from astrai.model.components.embedding import Embedding
+from astrai.model.components.linear import Linear
+from astrai.model.components.lora import LoRALinear
+from astrai.model.components.norm import RMSNorm
+from astrai.optim.composite import (
+    OptimizerFactory,
+    composite_state_dict,
+    composite_step,
+    composite_zero_grad,
+    refresh_param_groups,
+)
+
+NORA_EPS = 1e-10
+
+
+def _row_normalize(tensor: Tensor, eps: float) -> Tensor:
+    return tensor / tensor.norm(dim=-1, keepdim=True).clamp(min=eps)
+
+
+def nora_direction(update: Tensor, param: Tensor, eps: float = NORA_EPS) -> Tensor:
+    """Project an update onto each parameter row's tangent space and normalize."""
+    theta_hat = _row_normalize(param.to(torch.float32), eps)
+    update_fp32 = update.to(torch.float32)
+    radial = (update_fp32 * theta_hat).sum(dim=-1, keepdim=True) * theta_hat
+    direction = _row_normalize(update_fp32 - radial, eps)
+    return direction.to(update.dtype)
+
+
+def nora_lr_scale(lr: float, shape: torch.Size) -> float:
+    """Scale Nora's LR for tall ``[d_out, d_in]`` linear weights."""
+    return lr * math.sqrt(max(1.0, shape[-2] / shape[-1]))
+
+
+def _validate_complete_rows(param: Tensor) -> None:
+    if not isinstance(param, DTensor):
+        return
+    last_dim = param.ndim - 1
+    for placement in param.placements:
+        if isinstance(placement, Shard) and placement.dim % param.ndim == last_dim:
+            raise ValueError(
+                "Nora requires complete parameter rows, but this DTensor is sharded "
+                "along its last dimension"
+            )
+
+
+class Nora(Optimizer):
+    """Normalized Orthogonal Row Alignment for two-dimensional matrices."""
+
+    def __init__(
+        self,
+        params,
+        lr: float = 5e-3,
+        weight_decay: float = 0.0,
+        momentum: float = 0.95,
+        beta: float = 0.95,
+        nesterov: bool = True,
+        eps: float = NORA_EPS,
+    ):
+        if lr < 0:
+            raise ValueError(f"Invalid learning rate: {lr}")
+        if weight_decay < 0:
+            raise ValueError(f"Invalid weight decay: {weight_decay}")
+        if not 0 <= momentum <= 1:
+            raise ValueError(f"Invalid momentum: {momentum}")
+        if not 0 <= beta < 1:
+            raise ValueError(f"Invalid beta: {beta}")
+        if eps <= 0:
+            raise ValueError(f"Invalid epsilon: {eps}")
+
+        defaults = {
+            "lr": lr,
+            "weight_decay": weight_decay,
+            "momentum": momentum,
+            "beta": beta,
+            "nesterov": nesterov,
+            "eps": eps,
+        }
+        super().__init__(params, defaults)
+        for group in self.param_groups:
+            for param in group["params"]:
+                if param.ndim != 2:
+                    raise ValueError(
+                        f"Nora only supports 2D matrices, got shape {tuple(param.shape)}"
+                    )
+                _validate_complete_rows(param)
+
+    @torch.no_grad()
+    def step(self, closure=None):
+        loss = None
+        if closure is not None:
+            with torch.enable_grad():
+                loss = closure()
+
+        for group in self.param_groups:
+            lr = group["lr"]
+            weight_decay = group["weight_decay"]
+            momentum = group["momentum"]
+            beta = group["beta"]
+            nesterov = group["nesterov"]
+            eps = group["eps"]
+            for param in group["params"]:
+                if param.grad is None:
+                    continue
+                if param.grad.is_sparse:
+                    raise RuntimeError("Nora does not support sparse gradients")
+
+                grad = param.grad
+                state = self.state[param]
+                momentum_buffer = state.get("momentum_buffer")
+                if momentum_buffer is None:
+                    momentum_buffer = torch.zeros_like(grad)
+                momentum_buffer.lerp_(grad, 1 - beta)
+                update = (
+                    grad.lerp(momentum_buffer, momentum)
+                    if nesterov
+                    else momentum_buffer
+                )
+                direction = nora_direction(update, param, eps)
+
+                if weight_decay != 0:
+                    param.mul_(1 - lr * weight_decay)
+                param.add_(direction, alpha=-nora_lr_scale(lr, param.shape))
+                state["momentum_buffer"] = momentum_buffer
+
+        return loss
+
+
+class NAdamW(Optimizer):
+    """AdamW using the reference Nesterov first-moment update."""
+
+    def __init__(
+        self,
+        params,
+        lr: float = 3e-4,
+        betas: tuple[float, float] = (0.9, 0.999),
+        eps: float = 1e-8,
+        weight_decay: float = 0.1,
+    ):
+        beta1, beta2 = betas
+        if lr < 0:
+            raise ValueError(f"Invalid learning rate: {lr}")
+        if not 0 <= beta1 < 1 or not 0 <= beta2 < 1:
+            raise ValueError(f"Invalid betas: {betas}")
+        if eps <= 0:
+            raise ValueError(f"Invalid epsilon: {eps}")
+        if weight_decay < 0:
+            raise ValueError(f"Invalid weight decay: {weight_decay}")
+        defaults = {
+            "lr": lr,
+            "betas": betas,
+            "eps": eps,
+            "weight_decay": weight_decay,
+        }
+        super().__init__(params, defaults)
+
+    @torch.no_grad()
+    def step(self, closure=None):
+        loss = None
+        if closure is not None:
+            with torch.enable_grad():
+                loss = closure()
+
+        for group in self.param_groups:
+            beta1, beta2 = group["betas"]
+            eps = group["eps"]
+            lr = group["lr"]
+            weight_decay = group["weight_decay"]
+            for param in group["params"]:
+                if param.grad is None:
+                    continue
+                if param.grad.is_sparse:
+                    raise RuntimeError("NAdamW does not support sparse gradients")
+
+                grad = param.grad
+                state = self.state[param]
+                if not state:
+                    state["step"] = 0
+                    state["m"] = torch.zeros_like(param)
+                    state["v"] = torch.zeros_like(param)
+
+                state["step"] += 1
+                first_moment = state["m"]
+                second_moment = state["v"]
+                first_moment.mul_(beta1).add_(grad, alpha=1 - beta1)
+                second_moment.mul_(beta2).addcmul_(grad, grad, value=1 - beta2)
+
+                bias_correction1 = 1 - beta1 ** state["step"]
+                bias_correction2 = 1 - beta2 ** state["step"]
+                nesterov_moment = (
+                    beta1 * first_moment + (1 - beta1) * grad
+                ) / bias_correction1
+                corrected_second_moment = second_moment / bias_correction2
+
+                if weight_decay != 0:
+                    param.mul_(1 - lr * weight_decay)
+                param.addcdiv_(
+                    nesterov_moment,
+                    corrected_second_moment.sqrt().add_(eps),
+                    value=-lr,
+                )
+
+        return loss
+
+
+@dataclass
+class OptimizerParameterGroups:
+    nora: list[Tensor]
+    nadamw_decay: list[Tensor]
+    nadamw_no_decay: list[Tensor]
+
+
+def partition_optimizer_parameters(model: nn.Module) -> OptimizerParameterGroups:
+    """Partition trainable parameters by module role and parameter identity."""
+    nora_ids: set[int] = set()
+    no_decay_ids: set[int] = set()
+
+    for module_name, module in model.named_modules():
+        if isinstance(module, LoRALinear):
+            for param in module.parameters(recurse=False):
+                if param.requires_grad:
+                    no_decay_ids.add(id(param))
+            continue
+
+        if isinstance(module, (Embedding, RMSNorm)):
+            for param in module.parameters(recurse=False):
+                if param.requires_grad:
+                    no_decay_ids.add(id(param))
+            continue
+
+        if not isinstance(module, Linear):
+            continue
+
+        if module.bias is not None and module.bias.requires_grad:
+            no_decay_ids.add(id(module.bias))
+        if not module.weight.requires_grad:
+            continue
+        if module_name.rsplit(".", 1)[-1] == "lm_head":
+            no_decay_ids.add(id(module.weight))
+        elif module.weight.ndim == 2:
+            nora_ids.add(id(module.weight))
+
+    nora: list[Tensor] = []
+    nadamw_decay: list[Tensor] = []
+    nadamw_no_decay: list[Tensor] = []
+    seen: set[int] = set()
+    for param in model.parameters():
+        param_id = id(param)
+        if not param.requires_grad or param_id in seen:
+            continue
+        seen.add(param_id)
+        if param_id in no_decay_ids or param.ndim <= 1:
+            nadamw_no_decay.append(param)
+        elif param_id in nora_ids:
+            nora.append(param)
+        else:
+            nadamw_decay.append(param)
+
+    trainable_ids = {id(param) for param in model.parameters() if param.requires_grad}
+    grouped_ids = {id(param) for param in [*nora, *nadamw_decay, *nadamw_no_decay]}
+    if grouped_ids != trainable_ids:
+        missing = len(trainable_ids - grouped_ids)
+        extra = len(grouped_ids - trainable_ids)
+        raise RuntimeError(
+            f"Optimizer parameter partition is incomplete: missing={missing}, extra={extra}"
+        )
+
+    return OptimizerParameterGroups(nora, nadamw_decay, nadamw_no_decay)
+
+
+@OptimizerFactory.register("nora_nadamw")
+class NoraNAdamW(Optimizer):
+    """Nora for internal linear weights and NAdamW for remaining parameters."""
+
+    optimizer_name = "nora_nadamw"
+
+    def __init__(
+        self,
+        model: nn.Module,
+        lr: float = 3e-4,
+        weight_decay: float = 0.1,
+        nora_lr: float = 5e-3,
+        nora_weight_decay: float = 0.0,
+        nora_beta: float = 0.95,
+        nora_momentum: float = 0.95,
+    ):
+        groups = partition_optimizer_parameters(model)
+        all_params = [
+            *groups.nora,
+            *groups.nadamw_decay,
+            *groups.nadamw_no_decay,
+        ]
+        if not all_params:
+            raise ValueError(
+                "Cannot build an optimizer for a model with no trainable parameters"
+            )
+        super().__init__(all_params, {})
+
+        self.nora = (
+            Nora(
+                groups.nora,
+                lr=nora_lr,
+                weight_decay=nora_weight_decay,
+                momentum=nora_momentum,
+                beta=nora_beta,
+            )
+            if groups.nora
+            else None
+        )
+
+        nadamw_groups = []
+        if groups.nadamw_decay:
+            nadamw_groups.append(
+                {"params": groups.nadamw_decay, "weight_decay": weight_decay}
+            )
+        if groups.nadamw_no_decay:
+            nadamw_groups.append(
+                {"params": groups.nadamw_no_decay, "weight_decay": 0.0}
+            )
+        self.nadamw = NAdamW(nadamw_groups, lr=lr) if nadamw_groups else None
+        self.param_groups = refresh_param_groups([self.nora, self.nadamw])
+
+    @torch.no_grad()
+    def step(self, closure=None):
+        return composite_step(
+            [opt for opt in (self.nora, self.nadamw) if opt is not None],
+            closure,
+        )
+
+    def zero_grad(self, set_to_none: bool = True):
+        composite_zero_grad(
+            [opt for opt in (self.nora, self.nadamw) if opt is not None],
+            set_to_none,
+        )
+
+    def state_dict(self) -> dict[str, Any]:
+        return composite_state_dict({"nora": self.nora, "nadamw": self.nadamw})
+
+    def load_state_dict(self, state_dict: dict[str, Any]):
+        if "muon" in state_dict or "adamw" in state_dict:
+            raise ValueError(
+                "Checkpoint uses muon_adamw state; select optimizer='muon_adamw' "
+                "to resume it"
+            )
+        if "nora" not in state_dict or "nadamw" not in state_dict:
+            raise ValueError(
+                "Checkpoint optimizer state is not compatible with nora_nadamw"
+            )
+
+        saved_nora = state_dict["nora"]
+        saved_nadamw = state_dict["nadamw"]
+        if (self.nora is None) != (saved_nora is None):
+            raise ValueError("Checkpoint Nora parameter groups do not match the model")
+        if (self.nadamw is None) != (saved_nadamw is None):
+            raise ValueError(
+                "Checkpoint NAdamW parameter groups do not match the model"
+            )
+        if self.nora is not None:
+            self.nora.load_state_dict(saved_nora)
+        if self.nadamw is not None:
+            self.nadamw.load_state_dict(saved_nadamw)
+        self.param_groups = refresh_param_groups([self.nora, self.nadamw])

astrai/parallel/__init__.py

@@ -7,8 +7,9 @@ from astrai.parallel.executor import (
     FSDPExecutor,
     GradientState,
     NoneExecutor,
+    broadcast_state_dict,
+    create_ref_model,
 )
-from astrai.parallel.module import ColumnParallelLinear, RowParallelLinear
 from astrai.parallel.setup import (
     get_current_device,
     get_rank,
@@ -25,8 +26,6 @@ __all__ = [
     "only_on_rank",
     "setup_parallel",
     "spawn_parallel_fn",
-    "RowParallelLinear",
-    "ColumnParallelLinear",
     "ExecutorFactory",
     "BaseExecutor",
     "GradientState",
@@ -35,4 +34,6 @@ __all__ = [
     "NoneExecutor",
     "DDPExecutor",
     "FSDPExecutor",
+    "create_ref_model",
+    "broadcast_state_dict",
 ]

astrai/parallel/executor.py

@@ -4,17 +4,19 @@ import contextlib
 import logging
 import os
 from contextlib import contextmanager
-from typing import Optional, Tuple
+from typing import Any, Callable, Dict, Optional, Tuple
 
 import torch
 import torch.distributed as dist
 import torch.nn as nn
-from torch.distributed.fsdp import FullStateDictConfig, StateDictType
-from torch.distributed.fsdp import FullyShardedDataParallel as FSDP
+from torch.distributed.fsdp import (
+    FSDPModule,
+    fully_shard,
+)
+from torch.distributed.tensor import DTensor
 from torch.nn.parallel import DistributedDataParallel as DDP
 from torch.optim import Optimizer
 from torch.optim.lr_scheduler import LRScheduler
-from torch.utils.data import DataLoader
 
 from astrai.factory import BaseFactory
 from astrai.parallel.setup import get_rank, get_world_size
@@ -22,6 +24,82 @@ from astrai.parallel.setup import get_rank, get_world_size
 logger = logging.getLogger(__name__)
 
 
+def broadcast_state_dict(
+    state_dict: Optional[Dict[str, torch.Tensor]],
+    src: int = 0,
+) -> Optional[Dict[str, torch.Tensor]]:
+    """Broadcast a state_dict from *src* rank to all ranks.
+
+    Tensors stay on their original device (GPU) for the broadcast.
+    All ranks must call this collectively.
+
+    On non-distributed runs, returns *state_dict* unchanged.
+    """
+    if not dist.is_initialized() or dist.get_world_size() == 1:
+        return state_dict
+
+    rank = dist.get_rank()
+
+    # Broadcast metadata (keys, shapes, dtypes, device) so non-src ranks
+    # can allocate matching empty tensors on the correct device.
+    if rank == src:
+        device = next(iter(state_dict.values())).device
+        metadata = [
+            (k, tuple(v.shape), v.dtype, str(device)) for k, v in state_dict.items()
+        ]
+    else:
+        metadata = None
+    metadata_list = [metadata]
+    dist.broadcast_object_list(metadata_list, src=src)
+    metadata = metadata_list[0]
+
+    # Non-src ranks allocate empty tensors with the broadcasted metadata.
+    if rank != src:
+        state_dict = {
+            k: torch.empty(s, dtype=d, device=torch.device(dev))
+            for k, s, d, dev in metadata
+        }
+
+    # Broadcast each tensor in-place.
+    for tensor in state_dict.values():
+        dist.broadcast(tensor, src=src)
+
+    return state_dict
+
+
+def create_ref_model(
+    model_fn: Callable[[], nn.Module],
+    executor: Optional["BaseExecutor"] = None,
+    model: Optional[nn.Module] = None,
+    state_dict: Optional[Dict[str, torch.Tensor]] = None,
+    device: Optional[str] = None,
+) -> Optional[nn.Module]:
+    """Create a frozen reference model from executor or state dict.
+
+    In distributed mode (FSDP), ``unwrap_model`` returns ``None`` on
+    non-rank-0.  The state_dict is broadcast from rank-0 to all ranks
+    so every rank gets a complete copy.
+    """
+    if state_dict is None and executor is not None and model is not None:
+        state_dict = executor.unwrap_model(model)
+
+    # FSDP's unwrap_model returns None on non-rank-0. Broadcast from
+    # rank-0 so every rank receives a complete state_dict.
+    if executor is not None and executor.use_distributed:
+        state_dict = broadcast_state_dict(state_dict)
+
+    if state_dict is None:
+        return None
+
+    ref_model = model_fn()
+    ref_model.load_state_dict(state_dict)
+    ref_model.requires_grad_(False)
+    ref_model.eval()
+    if device is not None:
+        ref_model = ref_model.to(device=device)
+    return ref_model
+
+
 class GradientState:
     def __init__(self, grad_accum_steps: int = 1):
         self.num_steps = max(grad_accum_steps, 1)
@@ -86,19 +164,28 @@ class BaseExecutor:
 
     def prepare(
         self,
-        model: nn.Module,
-        optimizer: Optional[Optimizer] = None,
-        dataloader: Optional[DataLoader] = None,
-        scheduler: Optional[LRScheduler] = None,
-    ) -> Tuple[
-        nn.Module, Optional[Optimizer], Optional[DataLoader], Optional[LRScheduler]
-    ]:
+        model_fn: Callable[[], nn.Module],
+        optimizer_fn: Optional[Callable[[nn.Module], Optimizer]] = None,
+        scheduler_fn: Optional[Callable[[Optimizer], LRScheduler]] = None,
+        before_wrap: Optional[Callable[[nn.Module], nn.Module]] = None,
+        after_wrap: Optional[Callable[[nn.Module], nn.Module]] = None,
+    ) -> Tuple[nn.Module, Optional[Optimizer], Optional[LRScheduler]]:
+        model = model_fn()
+        if before_wrap is not None:
+            model = before_wrap(model)
         model = self._prepare_model(model)
-        if optimizer is not None:
+        if after_wrap is not None:
+            model = after_wrap(model)
+        optimizer = None
+        scheduler = None
+        if optimizer_fn is not None:
+            optimizer = optimizer_fn(model)
+            if scheduler_fn is not None:
+                scheduler = scheduler_fn(optimizer)
             optimizer = AccumOptimizer(optimizer, self.gradient_state)
-        if scheduler is not None:
-            scheduler = AccumScheduler(scheduler, self.gradient_state)
-        return model, optimizer, dataloader, scheduler
+            if scheduler is not None:
+                scheduler = AccumScheduler(scheduler, self.gradient_state)
+        return model, optimizer, scheduler
 
     def _prepare_model(self, model: nn.Module) -> nn.Module:
         return model
@@ -224,86 +311,118 @@ class DDPExecutor(BaseExecutor):
             return model.module.state_dict()
         return model.state_dict()
 
-    def _gather_state_dict(self, model: nn.Module):
-        if not self.use_distributed:
-            return self.unwrap_model(model)
-        if get_rank() != 0:
-            return None
-        return self.unwrap_model(model)
-
 
 @ExecutorFactory.register("fsdp")
 class FSDPExecutor(BaseExecutor):
+    """FSDP executor using `torch.distributed.fsdp.fully_shard` (per-module API).
+
+    Wraps each child module individually via ``fully_shard``.
+    Skips the root model because ``ABC + Generic[T]`` in the MRO makes
+    ``fully_shard``'s dynamic ``__class__`` assignment fail at the CPython level.
+    Original ``Parameter`` objects are preserved (as DTensors) — no
+    ``FlatParameter``, no ``use_orig_params=True`` hack.
+    """
+
     def __init__(
         self,
         grad_accum_steps: int = 1,
-        process_group=None,
-        sharding_strategy=None,
-        cpu_offload=None,
-        auto_wrap_policy=None,
-        backward_prefetch=None,
-        mixed_precision=None,
-        ignored_modules=None,
-        param_init_fn=None,
-        sync_module_states: bool = False,
-        forward_prefetch: bool = False,
-        limit_all_gathers: bool = True,
-        ignored_states=None,
-        device_mesh=None,
+        mesh: Optional[Any] = None,
+        mp_policy: Optional[Any] = None,
+        reshard_after_forward: bool = False,
     ):
         super().__init__(grad_accum_steps=grad_accum_steps)
-        self._fsdp_kwargs = {
-            k: v
-            for k, v in dict(
-                process_group=process_group,
-                sharding_strategy=sharding_strategy,
-                cpu_offload=cpu_offload,
-                auto_wrap_policy=auto_wrap_policy,
-                backward_prefetch=backward_prefetch,
-                mixed_precision=mixed_precision,
-                ignored_modules=ignored_modules,
-                param_init_fn=param_init_fn,
-                sync_module_states=sync_module_states,
-                forward_prefetch=forward_prefetch,
-                limit_all_gathers=limit_all_gathers,
-                use_orig_params=True,
-                ignored_states=ignored_states,
-                device_mesh=device_mesh,
-            ).items()
-            if v is not None
-        }
-        self._original_model: Optional[nn.Module] = None
+        self._mesh = mesh
+        self._mp_policy = mp_policy
+        self._reshard_after_forward = reshard_after_forward
 
     def _prepare_model(self, model: nn.Module) -> nn.Module:
         if not self.use_distributed:
             logger.warning("FSDP backend selected but world_size=1, model not wrapped")
             return model
-        self._original_model = model
-        device_id = torch.device("cuda", get_rank())
-        model = FSDP(model, device_id=device_id, **self._fsdp_kwargs)
-        logger.info("Model wrapped with FSDP (world_size=%d)", get_world_size())
+
+        kwargs = dict(
+            mesh=self._mesh,
+            mp_policy=self._mp_policy,
+            reshard_after_forward=self._reshard_after_forward,
+        )
+        kwargs = {k: v for k, v in kwargs.items() if v is not None}
+
+        for child in model.children():
+            if isinstance(child, nn.ModuleList):
+                for sub in child:
+                    fully_shard(sub, **kwargs)
+            else:
+                fully_shard(child, **kwargs)
+
+        logger.info(
+            "FSDP wrapping applied to %d direct children (root skipped for ABC compat)",
+            len(list(model.children())),
+        )
         return model
 
+    @contextmanager
     def _no_sync(self, model: nn.Module):
-        if isinstance(model, FSDP):
-            return model.no_sync()
-        return contextlib.nullcontext()
+        fsdp_modules = [m for m in model.modules() if isinstance(m, FSDPModule)]
+        if fsdp_modules:
+            for m in fsdp_modules:
+                m.set_requires_gradient_sync(False, recurse=True)
+            try:
+                yield
+            finally:
+                for m in fsdp_modules:
+                    m.set_requires_gradient_sync(True, recurse=True)
+        else:
+            yield
 
     def clip_grad_norm(self, model: nn.Module, max_norm: float) -> float:
-        if isinstance(model, FSDP) and self.use_distributed:
-            total_norm = model.clip_grad_norm_(max_norm)
-            if isinstance(total_norm, torch.Tensor):
-                return total_norm.item()
-            return total_norm
-        return super().clip_grad_norm(model, max_norm)
+        if not self.use_distributed:
+            return super().clip_grad_norm(model, max_norm)
+
+        # FSDP params are DTensors (sharded across ranks).
+        # torch.nn.utils.clip_grad_norm_ computes LOCAL norm per rank,
+        # so we must all-reduce to get the global norm before clipping.
+        local_norm = torch.nn.utils.get_total_norm(
+            [p.grad for p in model.parameters() if p.grad is not None],
+        )
+        if isinstance(local_norm, DTensor):
+            local_norm = local_norm.to_local()
+        total_norm_sq = local_norm**2
+        dist.all_reduce(total_norm_sq, op=dist.ReduceOp.SUM)
+        total_norm = total_norm_sq.sqrt()
+
+        clip_coef = max_norm / (total_norm + 1e-6)
+        clip_coef_clamped = torch.clamp(clip_coef, max=1.0)
+        for p in model.parameters():
+            if p.grad is not None:
+                p.grad.mul_(clip_coef_clamped)
+
+        return total_norm.item()
 
     def unwrap_model(self, model: nn.Module):
-        if isinstance(model, FSDP) and self.use_distributed:
-            with FSDP.state_dict_type(
-                model,
-                StateDictType.FULL_STATE_DICT,
-                FullStateDictConfig(offload_to_cpu=True, rank0_only=True),
-            ):
-                return model.state_dict()
+        if not self.use_distributed:
+            return model.state_dict()
 
-        return model.state_dict()
+        # unshard() and full_tensor() are collective ops — all ranks must
+        # participate. Non-rank-0 ranks still call them but discard results.
+        for module in model.modules():
+            if isinstance(module, FSDPModule):
+                module.unshard()
+
+        state_dict = model.state_dict()
+        result = {}
+        for k, v in state_dict.items():
+            if isinstance(v, DTensor):
+                full = v.full_tensor()
+                if get_rank() == 0:
+                    result[k] = full
+            elif get_rank() == 0:
+                result[k] = v
+
+        for module in model.modules():
+            if isinstance(module, FSDPModule):
+                module.reshard()
+
+        if get_rank() != 0:
+            return None
+
+        return result

astrai/parallel/module.py

@@ -1,115 +0,0 @@
-from typing import Dict
-
-import torch
-import torch.distributed as dist
-import torch.nn as nn
-import torch.nn.functional as F
-from torch import Tensor
-
-
-class ParallelModel(nn.Module):
-    def __init__(self, process_group: dist.ProcessGroup):
-        super().__init__()
-        self.process_group = process_group
-        self.rank = dist.get_rank(self.process_group)
-        self.world_size = dist.get_world_size(self.process_group)
-
-
-class RowParallelLinear(ParallelModel):
-    def __init__(
-        self,
-        process_group: dist.ProcessGroup,
-        in_features: int,
-        out_features: int,
-        bias: bool = True,
-        reduce_results: bool = True,
-    ):
-        super().__init__(process_group)
-
-        self.in_features = in_features
-        self.out_features = out_features
-        self.in_features_per_rank = in_features // self.world_size
-        self.reduce_results = reduce_results
-
-        if in_features % self.world_size != 0:
-            raise ValueError(
-                f"in_features must be divisible by world_size. Got {in_features} and {self.world_size}"
-            )
-
-        self.weight = nn.Parameter(torch.empty(out_features, self.in_features_per_rank))
-        self.bias = nn.Parameter(torch.zeros(out_features)) if bias else None
-
-    def forward(self, input: Tensor) -> Tensor:
-        output = F.linear(input, self.weight)
-
-        if self.reduce_results:
-            dist.all_reduce(output, op=dist.ReduceOp.SUM, group=self.process_group)
-
-        if self.bias is not None:
-            output += self.bias
-
-        return output
-
-    def load_state_dict(self, state_dict: Dict[str, Tensor]):
-        full_weight = state_dict.get("weight")
-        full_bias = state_dict.get("bias")
-
-        start_idx = self.rank * self.in_features_per_rank
-        end_idx = start_idx + self.in_features_per_rank
-        weight_slice = full_weight[:, start_idx:end_idx]
-        self.weight.data.copy_(weight_slice)
-
-        if self.bias is not None:
-            self.bias.data.copy_(full_bias)
-
-
-class ColumnParallelLinear(ParallelModel):
-    def __init__(
-        self,
-        process_group: dist.ProcessGroup,
-        in_features: int,
-        out_features: int,
-        bias: bool = True,
-        gather_results: bool = True,
-    ):
-        super().__init__(process_group)
-
-        self.in_features = in_features
-        self.out_features = out_features
-        self.out_features_per_rank = out_features // self.world_size
-        self.gather_results = gather_results
-
-        if out_features % self.world_size != 0:
-            raise ValueError(
-                f"out_features must be divisible by world_size. Got {out_features} and {self.world_size}"
-            )
-
-        self.weight = nn.Parameter(
-            torch.empty(self.out_features_per_rank, self.in_features)
-        )
-        self.bias = (
-            nn.Parameter(torch.zeros(self.out_features_per_rank)) if bias else None
-        )
-
-    def forward(self, input: Tensor) -> Tensor:
-        output = F.linear(input, self.weight, self.bias)
-
-        if self.gather_results:
-            output_list = [torch.empty_like(output) for _ in range(self.world_size)]
-            dist.all_gather(output_list, output, group=self.process_group)
-            output = torch.cat(output_list, dim=-1)
-
-        return output
-
-    def load_state_dict(self, state_dict: Dict[str, Tensor]):
-        full_weight = state_dict.get("weight")
-        full_bias = state_dict.get("bias")
-
-        start_idx = self.rank * self.out_features_per_rank
-        end_idx = start_idx + self.out_features_per_rank
-        weight_slice = full_weight[start_idx:end_idx, :]
-        self.weight.data.copy_(weight_slice)
-
-        if self.bias is not None:
-            bias_slice = full_bias[start_idx:end_idx]
-            self.bias.data.copy_(bias_slice)

astrai/parallel/setup.py

@@ -1,5 +1,8 @@
+import logging
 import os
+import signal
 import socket
+import threading
 from abc import ABC, abstractmethod
 from contextlib import contextmanager
 from functools import wraps
@@ -9,6 +12,10 @@ import torch
 import torch.distributed as dist
 import torch.multiprocessing as mp
 
+from astrai.signal_handler import install_early_signal_handlers
+
+logger = logging.getLogger(__name__)
+
 
 def find_free_port() -> str:
     with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
@@ -23,15 +30,13 @@ def get_current_device():
 def get_world_size() -> int:
     if dist.is_available() and dist.is_initialized():
         return dist.get_world_size()
-    else:
-        return 1
+    return int(os.environ.get("WORLD_SIZE", "1"))
 
 
 def get_rank() -> int:
     if dist.is_available() and dist.is_initialized():
         return dist.get_rank()
-    else:
-        return 0
+    return int(os.environ.get("RANK", "0"))
 
 
 @contextmanager
@@ -115,6 +120,7 @@ def _run_single_rank(
     func: Callable,
     kwargs: dict,
 ):
+    install_early_signal_handlers()
     with setup_parallel(
         rank=rank,
         world_size=world_size,
@@ -155,6 +161,7 @@ class TorchrunStrategy(LaunchStrategy):
     """External orchestrator (torchrun, SLURM, K8s) — env vars pre-set."""
 
     def launch(self, func: Callable, **kwargs):
+        install_early_signal_handlers()
         rank = int(os.environ["RANK"])
         world_size = int(os.environ["WORLD_SIZE"])
         local_rank = int(os.environ.get("LOCAL_RANK", rank))
@@ -188,6 +195,7 @@ class LocalStrategy(LaunchStrategy):
             _run_single_rank(0, *args)
             return
 
+        install_early_signal_handlers()
         ctx = mp.start_processes(
             _run_single_rank,
             args=args,
@@ -195,28 +203,57 @@ class LocalStrategy(LaunchStrategy):
             start_method=self.start_method,
             join=False,
         )
+
+        parent_stop = threading.Event()
+        original_handlers = {}
+
+        def _parent_handler(signum, frame):
+            sig = signal.Signals(signum)
+            logger.warning(
+                "Parent (pid=%d) received %s, forwarding to children...",
+                os.getpid(),
+                sig.name,
+            )
+            parent_stop.set()
+            for p in ctx.processes:
+                if p.is_alive():
+                    p.terminate()
+
+        for sig in (signal.SIGTERM, signal.SIGINT):
+            prev = signal.signal(sig, _parent_handler)
+            if prev not in (signal.SIG_DFL, signal.SIG_IGN, None, _parent_handler):
+                original_handlers[sig] = prev
+
         try:
-            while not ctx.join():
+            while not ctx.join() and not parent_stop.is_set():
                 pass
         except BaseException:
+            logger.warning(
+                "Parent received unexpected exception, terminating children..."
+            )
             for p in ctx.processes:
-                p.terminate()
-            ctx.join()
+                if p.is_alive():
+                    p.terminate()
             raise
+        finally:
+            for sig, handler in original_handlers.items():
+                signal.signal(sig, handler)
+
+            for p in ctx.processes:
+                p.join()
+
+            ctx.join()
 
 
-def _detect_launcher() -> str:
-    """Detect the distributed launcher from environment.
-
-    Returns one of: "torchelastic", "torchrun", "external", "local".
-    """
+def _is_external_launcher() -> bool:
+    """Whether an external launcher (torchrun/elastic/manual env) started us."""
     if dist.is_torchelastic_launched():
-        return "torchelastic"
+        return True
     if "LOCAL_WORLD_SIZE" in os.environ:
-        return "torchrun"
+        return True
     if "RANK" in os.environ and "WORLD_SIZE" in os.environ:
-        return "external"
-    return "local"
+        return True
+    return False
 
 
 def spawn_parallel_fn(
@@ -231,8 +268,7 @@ def spawn_parallel_fn(
 ):
     if master_port is None:
         master_port = find_free_port()
-    launcher = _detect_launcher()
-    if launcher in ("torchelastic", "torchrun", "external"):
+    if _is_external_launcher():
         strategy = TorchrunStrategy(
             world_size, backend, master_addr, master_port, device_type, start_method
         )

astrai/preprocessing/__init__.py

@@ -8,12 +8,14 @@ from astrai.preprocessing.builder import (
 from astrai.preprocessing.packing import (
     PackingStrategy,
     PackingStrategyFactory,
+    plan_bfd,
 )
 from astrai.preprocessing.pipeline import Pipeline, filter_by_length
 from astrai.preprocessing.position_id import (
     PositionIdStrategy,
     PositionIdStrategyFactory,
 )
+from astrai.preprocessing.transform import TokenizeTransform
 from astrai.preprocessing.writer import (
     StoreWriter,
     StoreWriterFactory,
@@ -32,5 +34,7 @@ __all__ = [
     "SingleOutputMaskBuilder",
     "StoreWriter",
     "StoreWriterFactory",
+    "TokenizeTransform",
     "filter_by_length",
+    "plan_bfd",
 ]

astrai/preprocessing/builder.py

@@ -94,6 +94,97 @@ class SectionRenderer:
 
         return all_ids, loss_mask
 
+    def process_sections_batch(
+        self,
+        items: list[dict],
+        sections: list,
+        config,
+        tokenizer,
+        *,
+        is_top_level=False,
+        filter_text=True,
+    ):
+        """Render and tokenize a group of records with batched Rust tokenization."""
+        has_template = any(s.get("template") for s in sections)
+        is_text_config = not has_template and all(
+            s["action"] == "train" for s in sections
+        )
+        plans: list[list[tuple[str, str, bool]]] = []
+
+        for item in items:
+            plan: list[tuple[str, str, bool]] = []
+            first_section = True
+            for sec in sections:
+                field = sec["field"]
+                action = sec["action"]
+                use_template = sec.get("template", False)
+                add_special = sec.get(
+                    "add_special_tokens", not use_template and first_section
+                )
+
+                if use_template:
+                    messages = item.get(field)
+                    if not isinstance(messages, list) or not messages:
+                        continue
+                    for msg in messages:
+                        role = msg.get("role", "")
+                        rendered = tokenizer.apply_chat_template(
+                            [msg], tokenize=False, add_generation_prompt=False
+                        )
+                        plan.append(
+                            (rendered, _resolve_action(action, role, config), False)
+                        )
+                else:
+                    text = str(item.get(field, ""))
+                    if not text.strip():
+                        continue
+                    if is_text_config and filter_text:
+                        pp = config.preprocessing
+                        if pp.min_chars > 0 and len(text) < pp.min_chars:
+                            continue
+                        if len(text) > pp.max_chars:
+                            continue
+                    plan.append((text, action, add_special))
+
+                first_section = False
+            plans.append(plan)
+
+        encoded: dict[tuple[int, int], list[int]] = {}
+        for add_special in (False, True):
+            refs = [
+                (item_idx, unit_idx, text)
+                for item_idx, plan in enumerate(plans)
+                for unit_idx, (text, _, add) in enumerate(plan)
+                if add == add_special
+            ]
+            if not refs:
+                continue
+            ids_batch = tokenizer.encode(
+                [text for _, _, text in refs], add_special_tokens=add_special
+            )
+            for (item_idx, unit_idx, _), ids in zip(refs, ids_batch):
+                encoded[(item_idx, unit_idx)] = ids
+
+        outputs = []
+        max_len = config.preprocessing.max_seq_len
+        for item_idx, plan in enumerate(plans):
+            all_ids = []
+            loss_mask = []
+            if is_top_level and has_template and tokenizer.bos_token_id is not None:
+                all_ids.append(tokenizer.bos_token_id)
+                loss_mask.append(0)
+            for unit_idx, (_, action, _) in enumerate(plan):
+                ids = encoded[(item_idx, unit_idx)]
+                all_ids.extend(ids)
+                loss_mask.extend([1 if action == "train" else 0] * len(ids))
+            all_ids = all_ids[:max_len]
+            loss_mask = loss_mask[: len(all_ids)]
+            if not all_ids or (is_top_level and has_template and len(all_ids) <= 1):
+                outputs.append((None, None))
+            else:
+                outputs.append((all_ids, loss_mask))
+        return outputs
+
     def process_list_field(self, item: dict, sections: list, config, tokenizer):
         """Tokenize a list-valued field, preserving per-element boundaries.
 
@@ -147,6 +238,42 @@ class SectionRenderer:
             return None, None
         return per_item_ids, per_item_masks
 
+    def process_list_field_batch(self, items, sections, config, tokenizer):
+        per_item_ids = [[] for _ in items]
+        per_item_masks = [[] for _ in items]
+
+        for sec in sections:
+            wrappers = []
+            owners = []
+            field = sec["field"]
+            for item_idx, item in enumerate(items):
+                values = item.get(field)
+                if not isinstance(values, list):
+                    continue
+                for val in values:
+                    if sec.get("template", False) and not isinstance(val, list):
+                        continue
+                    wrappers.append({field: val if isinstance(val, list) else str(val)})
+                    owners.append(item_idx)
+
+            rendered = self.process_sections_batch(
+                wrappers,
+                [sec],
+                config,
+                tokenizer,
+                is_top_level=False,
+                filter_text=False,
+            )
+            for owner, (ids, mask) in zip(owners, rendered):
+                if ids:
+                    per_item_ids[owner].append(ids)
+                    per_item_masks[owner].append(mask)
+
+        return [
+            (ids, masks) if ids else (None, None)
+            for ids, masks in zip(per_item_ids, per_item_masks)
+        ]
+
     @staticmethod
     def is_value_section(sections: list) -> bool:
         return len(sections) == 1 and sections[0].get("action") == "value"
@@ -214,6 +341,9 @@ class BaseMaskBuilder(ABC):
     @abstractmethod
     def build(self, item: dict, config, tokenizer) -> Optional[dict]: ...
 
+    def build_batch(self, items: list[dict], config, tokenizer) -> list[Optional[dict]]:
+        return [self.build(item, config, tokenizer) for item in items]
+
 
 class MaskBuilderFactory(BaseFactory["BaseMaskBuilder"]):
     pass
@@ -248,6 +378,27 @@ class SingleOutputMaskBuilder(BaseMaskBuilder):
             result["loss_mask"] = mask
         return result
 
+    def build_batch(self, items, config, tokenizer):
+        sections = config.input.sections
+        if not sections:
+            return [None] * len(items)
+        rendered = self.renderer.process_sections_batch(
+            items, sections, config, tokenizer, is_top_level=True
+        )
+        results = []
+        for item, (ids, mask) in zip(items, rendered):
+            if ids is None:
+                results.append(None)
+                continue
+            result = {
+                "sequence": ids,
+                "domain": _extract_domain(item, config.output.domain_key),
+            }
+            if not all(m == 1 for m in mask):
+                result["loss_mask"] = mask
+            results.append(result)
+        return results
+
 
 @MaskBuilderFactory.register("multi")
 class MultiOutputMaskBuilder(BaseMaskBuilder):
@@ -265,7 +416,11 @@ class MultiOutputMaskBuilder(BaseMaskBuilder):
             return None
 
         result: dict = {}
-        any_output = False
+        required_outputs = {
+            output_key
+            for output_key, spec in sources_spec.items()
+            if spec.get("sections")
+        }
 
         for output_key, spec in sources_spec.items():
             sections = spec.get("sections", [])
@@ -277,7 +432,6 @@ class MultiOutputMaskBuilder(BaseMaskBuilder):
                 if ids is None:
                     continue
                 result[output_key] = ids
-                any_output = True
                 continue
 
             list_field = spec.get("list_field", False)
@@ -293,7 +447,6 @@ class MultiOutputMaskBuilder(BaseMaskBuilder):
                 result[output_key] = ids
                 if mask is not None:
                     result[mask_key] = mask
-                any_output = True
                 continue
 
             ids, mask = self.renderer.process_sections(
@@ -309,14 +462,60 @@ class MultiOutputMaskBuilder(BaseMaskBuilder):
             elif "mask_key" in spec:
                 result[mask_key] = mask
 
-            any_output = True
-
-        if not any_output:
+        if not required_outputs or not required_outputs.issubset(result):
             return None
 
         result["domain"] = _extract_domain(item, config.output.domain_key)
         return result
 
+    def build_batch(self, items, config, tokenizer):
+        sources_spec = getattr(config.input, "sources", None)
+        if not sources_spec:
+            return [None] * len(items)
+
+        results = [{} for _ in items]
+        required_outputs = {
+            output_key
+            for output_key, spec in sources_spec.items()
+            if spec.get("sections")
+        }
+        for output_key, spec in sources_spec.items():
+            sections = spec.get("sections", [])
+            if not sections:
+                continue
+            if self.renderer.is_value_section(sections):
+                for item, result in zip(items, results):
+                    value = self.renderer.extract_raw_value(item, sections)
+                    if value is not None:
+                        result[output_key] = value
+                continue
+
+            mask_key = spec.get("mask_key", f"{output_key}_mask")
+            if spec.get("list_field", False):
+                rendered = self.renderer.process_list_field_batch(
+                    items, sections, config, tokenizer
+                )
+            else:
+                rendered = self.renderer.process_sections_batch(
+                    items, sections, config, tokenizer, is_top_level=True
+                )
+
+            for result, (ids, mask) in zip(results, rendered):
+                if ids is None:
+                    continue
+                result[output_key] = ids
+                if spec.get("list_field", False) or not all(m == 1 for m in mask):
+                    result[mask_key] = mask
+                elif "mask_key" in spec:
+                    result[mask_key] = mask
+
+        return [
+            ({**result, "domain": _extract_domain(item, config.output.domain_key)})
+            if required_outputs and required_outputs.issubset(result)
+            else None
+            for item, result in zip(items, results)
+        ]
+
 
 @MaskBuilderFactory.register("sectioned")
 class SectionedMaskBuilder(BaseMaskBuilder):
@@ -335,3 +534,9 @@ class SectionedMaskBuilder(BaseMaskBuilder):
         if sources_spec:
             return self._multi.build(item, config, tokenizer)
         return self._single.build(item, config, tokenizer)
+
+    def build_batch(self, items, config, tokenizer):
+        sources_spec = getattr(config.input, "sources", None)
+        if sources_spec:
+            return self._multi.build_batch(items, config, tokenizer)
+        return self._single.build_batch(items, config, tokenizer)

astrai/preprocessing/core.py

@@ -0,0 +1,124 @@
+"""Shared preprocessing kernel used by both :class:`Pipeline` and
+:class:`TokenizeTransform`.
+
+The two entry points previously duplicated ~60 % of their logic:
+record iteration, mask-builder invocation, primary-id extraction,
+per-key accumulation, dtype inference and position-id generation.
+This module factors out the common core as pure functions so that
+the online (``TokenizeTransform``) and offline (``Pipeline``) paths
+stay in lockstep.
+"""
+
+from itertools import chain
+from typing import Dict, Iterator, List, Optional
+
+import torch
+
+from astrai.config.preprocess_config import PipelineConfig
+from astrai.preprocessing.builder import MaskBuilderFactory
+from astrai.preprocessing.position_id import PositionIdStrategyFactory
+from astrai.tokenize import AutoTokenizer
+
+
+def build_preprocessing_components(config: PipelineConfig, tokenizer_path: str):
+    """Load tokenizer, mask builder and position-id strategy together.
+
+    Both ``Pipeline`` and ``TokenizeTransform`` need the same triple;
+    centralising the construction avoids drift (e.g. one path forgetting
+    to create the position-id strategy).
+    """
+    tokenizer = AutoTokenizer.from_pretrained(tokenizer_path)
+    mask_builder = MaskBuilderFactory.create("sectioned")
+    position_strategy = PositionIdStrategyFactory.create(
+        config.output.position_ids_mode
+    )
+    return tokenizer, mask_builder, position_strategy
+
+
+def primary_ids(result: dict) -> List[int]:
+    """Return the first flat int-list value in *result*.
+
+    Used for token counting and position-id generation when the
+    primary key name is not known (DPO uses ``chosen``, GRPO uses
+    ``prompts``, SFT uses ``sequence``).
+    """
+    for val in result.values():
+        if isinstance(val, list) and val and isinstance(val[0], int):
+            return val
+    return []
+
+
+def infer_dtype(ids: List) -> torch.dtype:
+    """Float values become float32, everything else int32."""
+    if ids and isinstance(ids[0], float):
+        return torch.float32
+    return torch.int32
+
+
+def iter_raw_records(
+    records: List[dict],
+    mask_builder,
+    config: PipelineConfig,
+    tokenizer,
+) -> Iterator[dict]:
+    """Yield mask-builder output dicts for each record, skipping failures.
+
+    Drops ``domain`` from the result (callers that need it should read
+    it before calling this).  Each yielded dict maps a key
+    (``sequence``, ``chosen``, ``responses``…) to either a flat
+    ``List[int]`` or a nested ``List[List[int]]`` (GRPO responses/masks).
+    """
+    for item in records:
+        result = mask_builder.build(item, config, tokenizer)
+        if result is None:
+            continue
+        result.pop("domain", None)
+        if not primary_ids(result):
+            continue
+        yield result
+
+
+def to_per_record_tensors(
+    raw: Dict[str, list],
+) -> Dict[str, List[torch.Tensor]]:
+    """Convert an accumulated ``{key: [per-record ids]}`` dict to tensors.
+
+    Handles three shapes transparently:
+
+    - ``List[int]`` per record (``sequence``, ``chosen``…) → one tensor per record.
+    - ``List[List[int]]`` per record (GRPO ``responses``/``masks``) → one
+      ``List[Tensor]`` per record (nested), preserving the per-response
+      boundary so downstream code can index responses individually.
+    - ``List[int]`` for the whole shard (pre-packed keys) → single tensor.
+
+    The detection mirrors the previous inline logic in
+    ``Pipeline._flush`` and ``TokenizeTransform.apply``.
+    """
+    tensors: Dict[str, List[torch.Tensor]] = {}
+    for key, ids_list in raw.items():
+        if ids_list and isinstance(ids_list[0], list):
+            tensors[key] = [
+                [torch.tensor(sub, dtype=infer_dtype(sub)) for sub in ids]
+                if ids and isinstance(ids[0], list)
+                else torch.tensor(ids, dtype=infer_dtype(ids))
+                for ids in ids_list
+            ]
+        else:
+            tensors[key] = [
+                torch.tensor(list(chain.from_iterable(ids_list)), dtype=torch.int32)
+            ]
+    return tensors
+
+
+def build_position_ids(
+    sequences: List[List[int]],
+    strategy,
+) -> Optional[List[int]]:
+    """Generate position ids for *sequences* using *strategy*.
+
+    Returns ``None`` when the strategy produces no ids (e.g. ``none``
+    mode), so callers can skip attaching the key instead of storing
+    an empty list.
+    """
+    pos_ids = strategy.generate(sequences)
+    return pos_ids or None

astrai/preprocessing/packing.py

@@ -19,6 +19,43 @@ def _truncate(seq: List[int], max_len: int, mode: str) -> List[int]:
     return seq[:max_len]
 
 
+def plan_bfd(
+    sequences: List[List[int]], max_packed_len: int, truncation_mode: str = "keep_start"
+) -> List[List[int]]:
+    """Best-Fit Decreasing bin packing of *sequences* into bins.
+
+    Returns a list of bins, each bin a list of original indices into
+    *sequences*.  Bin capacities are respected on the *truncated*
+    length of each sequence (so a sequence longer than
+    *max_packed_len* counts at *max_packed_len*).
+
+    Pure index-based so callers can apply the same plan to any
+    aligned key (``loss_mask``, ``position_ids``…).
+    """
+    n = len(sequences)
+    order = sorted(range(n), key=lambda i: len(sequences[i]), reverse=True)
+    bins: List[List[int]] = []
+    bin_lengths: List[int] = []
+
+    for orig_idx in order:
+        seq_len = len(_truncate(sequences[orig_idx], max_packed_len, truncation_mode))
+        best_bin = None
+        best_remain = max_packed_len + 1
+        for i, bl in enumerate(bin_lengths):
+            remain = max_packed_len - bl
+            if seq_len <= remain < best_remain:
+                best_remain = remain
+                best_bin = i
+        if best_bin is not None:
+            bins[best_bin].append(orig_idx)
+            bin_lengths[best_bin] += seq_len
+        else:
+            bins.append([orig_idx])
+            bin_lengths.append(seq_len)
+
+    return bins
+
+
 class PackingStrategy(ABC):
     """Reorder and truncate sequences within a shard."""
 
@@ -70,7 +107,7 @@ class BFDPacking(PackingStrategy):
         sequences = keys.get("sequence", [])
         if not sequences:
             return keys
-        bins = self._plan(sequences, max_packed_len, truncation_mode)
+        bins = plan_bfd(sequences, max_packed_len, truncation_mode)
 
         packed: Dict[str, List[List[int]]] = {}
         for k, vals in keys.items():
@@ -91,35 +128,6 @@ class BFDPacking(PackingStrategy):
             result.extend(vals[i])
         return result
 
-    @staticmethod
-    def _plan(
-        sequences: List[List[int]], max_packed_len: int, truncation_mode: str
-    ) -> List[List[int]]:
-        n = len(sequences)
-        order = sorted(range(n), key=lambda i: len(sequences[i]), reverse=True)
-        bins: List[List[int]] = []
-        bin_lengths: List[int] = []
-
-        for orig_idx in order:
-            seq_len = len(
-                _truncate(sequences[orig_idx], max_packed_len, truncation_mode)
-            )
-            best_bin = None
-            best_remain = max_packed_len + 1
-            for i, bl in enumerate(bin_lengths):
-                remain = max_packed_len - bl
-                if seq_len <= remain < best_remain:
-                    best_remain = remain
-                    best_bin = i
-            if best_bin is not None:
-                bins[best_bin].append(orig_idx)
-                bin_lengths[best_bin] += seq_len
-            else:
-                bins.append([orig_idx])
-                bin_lengths.append(seq_len)
-
-        return bins
-
 
 @PackingStrategyFactory.register("bfd_split")
 class BFDSplitPacking(BFDPacking):

astrai/preprocessing/pipeline.py

@@ -1,9 +1,13 @@
 """Config-driven JSONL preprocessing pipeline.
 
 Composes a :class:`BaseMaskBuilder` (selected by ``input.type``) with
-sharding and flush to ``.h5`` / ``.bin`` storage.  Packing, position-id
+sharding and flush to ``.bin`` storage.  Packing, position-id
 generation and storage writing are each delegated to pluggable strategies,
 dispatched by configuration keys.
+
+Record iteration, mask building, primary-id extraction and per-key
+accumulation are shared with :class:`TokenizeTransform` via the
+:mod:`astrai.preprocessing.core` helpers.
 """
 
 import json
@@ -17,11 +21,12 @@ import torch
 import tqdm
 
 from astrai.config.preprocess_config import PipelineConfig
-from astrai.preprocessing.builder import MaskBuilderFactory
+from astrai.preprocessing.core import (
+    build_preprocessing_components,
+    primary_ids,
+)
 from astrai.preprocessing.packing import PackingStrategyFactory
-from astrai.preprocessing.position_id import PositionIdStrategyFactory
 from astrai.preprocessing.writer import StoreWriterFactory
-from astrai.tokenize import AutoTokenizer
 
 logger = logging.getLogger(__name__)
 
@@ -64,20 +69,21 @@ class Pipeline:
         self.output_dir = output_dir
         self.tokenizer_path = tokenizer_path
 
-        self.mask_builder = MaskBuilderFactory.create("sectioned")
+        self.tokenizer, self.mask_builder, self._position_id = (
+            build_preprocessing_components(config, tokenizer_path)
+        )
         self._packer = PackingStrategyFactory.create(
             config.preprocessing.packing_strategy
         )
-        self._position_id = PositionIdStrategyFactory.create(
-            config.output.position_ids_mode
-        )
         self._writer = StoreWriterFactory.create(config.output.storage_format)
 
     def transform(self, item: dict) -> Optional[dict]:
-        return self.mask_builder.build(item, self.config, self._tokenizer)
+        return self.mask_builder.build(item, self.config, self.tokenizer)
+
+    def transform_batch(self, items: list[dict]) -> list[Optional[dict]]:
+        return self.mask_builder.build_batch(items, self.config, self.tokenizer)
 
     def run(self):
-        self._tokenizer = AutoTokenizer.from_pretrained(self.tokenizer_path)
         domains: dict = defaultdict(lambda: defaultdict(list))
         total_tokens = 0
         shard_idx: dict[str, int] = defaultdict(int)
@@ -85,59 +91,59 @@ class Pipeline:
 
         pp = self.config.preprocessing
 
-        for item in tqdm.tqdm(
-            self._iter_items(), desc="Tokenizing", unit="docs", mininterval=0.5
-        ):
-            if pp.max_items and count >= pp.max_items:
-                break
-
+        progress = tqdm.tqdm(desc="Tokenizing", unit="docs", mininterval=0.5)
+        stop = False
+        for items in self._iter_batches(pp.batch_size):
+            progress.update(len(items))
             try:
-                result = self.transform(item)
+                results = self.transform_batch(items)
             except Exception:
                 logger.warning(
-                    "Failed to process item #%d, skipping", count + 1, exc_info=True
+                    "Failed to process batch, retrying records individually",
+                    exc_info=True,
                 )
-                continue
-            if result is None:
-                continue
+                results = []
+                for item in items:
+                    try:
+                        results.append(self.transform(item))
+                    except Exception:
+                        logger.warning(
+                            "Failed to process item, skipping", exc_info=True
+                        )
+                        results.append(None)
 
-            domain = result.pop("domain", "__default__")
+            for result in results:
+                if pp.max_items and count >= pp.max_items:
+                    stop = True
+                    break
+                if result is None:
+                    continue
 
-            is_multi = bool(getattr(self.config.input, "sources", None))
-            if is_multi:
-                ids = self._primary_ids(result)
-            else:
-                ids = result.pop("sequence")
-                result["sequence"] = ids
+                domain = result.pop("domain", "__default__")
+                ids = primary_ids(result)
+                if not ids:
+                    continue
 
-            if not ids:
-                continue
+                bucket = domains[domain]
+                self._align_bucket(bucket, result, ids)
+                for key, val in result.items():
+                    bucket[key].append(val)
 
-            bucket = domains[domain]
-            self._align_bucket(bucket, result, ids)
-            for key, val in result.items():
-                bucket[key].append(val)
+                count += 1
+                total_tokens += len(ids)
 
-            count += 1
-            total_tokens += len(ids)
+                if total_tokens >= self.config.output.max_tokens_per_shard:
+                    self._flush(domains, shard_idx)
+                    domains.clear()
+                    total_tokens = 0
+            if stop:
+                break
 
-            if total_tokens >= self.config.output.max_tokens_per_shard:
-                self._flush(domains, shard_idx)
-                domains.clear()
-                total_tokens = 0
+        progress.close()
 
         if total_tokens > 0:
             self._flush(domains, shard_idx)
 
-    @staticmethod
-    def _primary_ids(result: dict) -> list:
-        """Return the first list-valued entry in *result* as the primary id
-        sequence for token counting."""
-        for val in result.values():
-            if isinstance(val, list) and val and isinstance(val[0], int):
-                return val
-        return []
-
     @staticmethod
     def _align_bucket(bucket: dict, result: dict, ids: list):
         """Pad previously-accumulated keys that are missing from *result*."""
@@ -162,6 +168,17 @@ class Pipeline:
                             continue
                         yield json.loads(line)
 
+    def _iter_batches(self, batch_size: int):
+        batch_size = max(1, batch_size)
+        batch = []
+        for item in self._iter_items():
+            batch.append(item)
+            if len(batch) >= batch_size:
+                yield batch
+                batch = []
+        if batch:
+            yield batch
+
     def _flush(self, domains, shard_idx):
         for domain, keys in domains.items():
             idx = shard_idx[domain]
@@ -170,39 +187,12 @@ class Pipeline:
             original_sequences = keys.get("sequence", [])
             mode = self.config.output.position_ids_mode
 
-            if mode == "doc_reset" and original_sequences:
-                keys["position_ids"] = [list(range(len(s))) for s in original_sequences]
-
+            keys = self._inject_doc_reset_position_ids(keys, mode, original_sequences)
             keys = self._packer.apply(dict(keys), pp.max_packed_len, pp.truncation_mode)
-
-            tensors: Dict[str, List[torch.Tensor]] = {}
-            for key, ids_list in keys.items():
-                dt = _STR_TO_DTYPE.get(
-                    self.config.output.dtype.get(key, "int32"), torch.int32
-                )
-                # GRPO multi-response keys store List[List[int]] per record
-                # (responses/masks).  Rewards store List[float] per record.
-                # Both produce List[Tensor] (one tensor per record), but
-                # responses need inner flattening while rewards do not.
-                if ids_list and isinstance(ids_list[0], list):
-                    tensors[key] = [
-                        torch.tensor(
-                            list(chain.from_iterable(ids))
-                            if ids and isinstance(ids[0], list)
-                            else ids,
-                            dtype=dt,
-                        )
-                        for ids in ids_list
-                    ]
-                else:
-                    tensors[key] = [
-                        torch.tensor(list(chain.from_iterable(ids_list)), dtype=dt)
-                    ]
-
-            if mode == "continuous" and original_sequences:
-                pos_ids = self._position_id.generate(keys.get("sequence", []))
-                if pos_ids:
-                    tensors["position_ids"] = [torch.tensor(pos_ids, dtype=torch.int32)]
+            tensors = self._to_tensors(keys)
+            tensors = self._inject_continuous_position_ids(
+                tensors, mode, keys.get("sequence", [])
+            )
 
             self._writer.save(self.output_dir, domain, idx, tensors)
             shard_idx[domain] = idx + 1
@@ -212,3 +202,76 @@ class Pipeline:
                 f"  saved {domain}/shard_{idx:04d}  "
                 f"({tensors[first_key][0].numel():,} tokens)"
             )
+
+    def _inject_doc_reset_position_ids(
+        self,
+        keys: Dict[str, list],
+        mode: str,
+        original_sequences: List[List[int]],
+    ) -> Dict[str, list]:
+        """Attach per-document position_ids before packing (``doc_reset``).
+
+        ``doc_reset`` position ids must enter the packer so that each
+        packed bin concatenates the per-doc ranges in bin order.  The
+        per-record structure ``[range(len(s)) for s in seqs]`` is required
+        by the packer (it concatenates per-record lists per bin); the
+        ``PositionIdStrategy.generate`` flattens, so it cannot be used
+        directly here — it is only consulted for the ``continuous``
+        post-packing path.
+        """
+        if mode != "doc_reset" or not original_sequences:
+            return keys
+        keys["position_ids"] = [list(range(len(s))) for s in original_sequences]
+        return keys
+
+    def _inject_continuous_position_ids(
+        self,
+        tensors: Dict[str, List[torch.Tensor]],
+        mode: str,
+        packed_sequences: List[List[int]],
+    ) -> Dict[str, List[torch.Tensor]]:
+        """Attach a single continuous position_ids tensor after packing.
+
+        ``continuous`` mode spans the whole shard (post-packing), so it
+        cannot participate in bin packing — it is computed from the
+        packed sequences and appended directly to the tensor dict.
+        """
+        if mode != "continuous" or not packed_sequences:
+            return tensors
+        pos_ids = self._position_id.generate(packed_sequences)
+        if pos_ids:
+            tensors["position_ids"] = [torch.tensor(pos_ids, dtype=torch.int32)]
+        return tensors
+
+    def _to_tensors(self, keys: Dict[str, list]) -> Dict[str, List[torch.Tensor]]:
+        """Convert packed per-key id lists to tensors.
+
+        Honours ``config.output.dtype`` overrides per key; falls back to
+        ``int32``.  Handles three shapes (see
+        :func:`astrai.preprocessing.core.to_per_record_tensors` for the
+        equivalent online-path helper):
+        - ``List[int]`` per record → one tensor per record.
+        - ``List[List[int]]`` per record (GRPO responses/masks) → one tensor
+          per record, inner lists flattened.
+        - ``List[int]`` for the whole shard (pre-packed keys) → single tensor.
+        """
+        tensors: Dict[str, List[torch.Tensor]] = {}
+        for key, ids_list in keys.items():
+            dt = _STR_TO_DTYPE.get(
+                self.config.output.dtype.get(key, "int32"), torch.int32
+            )
+            if ids_list and isinstance(ids_list[0], list):
+                tensors[key] = [
+                    torch.tensor(
+                        list(chain.from_iterable(ids))
+                        if ids and isinstance(ids[0], list)
+                        else ids,
+                        dtype=dt,
+                    )
+                    for ids in ids_list
+                ]
+            else:
+                tensors[key] = [
+                    torch.tensor(list(chain.from_iterable(ids_list)), dtype=dt)
+                ]
+        return tensors

astrai/preprocessing/transform.py

@@ -0,0 +1,92 @@
+"""Tokenization transform for JSONL record streams.
+
+Bridges the Reader layer (``JsonlStore`` reads raw JSON records) and the
+Dataset layer (expects per-record tensors).  Holds the tokenizer,
+mask-builder and position-id strategy together so that I/O code stays
+free of model dependencies.
+
+The record-processing core (mask building, primary-id extraction,
+per-key tensorisation, position-id generation) is shared with
+:class:`astrai.preprocessing.pipeline.Pipeline` via the
+:mod:`astrai.preprocessing.core` helpers.
+"""
+
+import json
+from pathlib import Path
+from typing import Dict, List
+
+import torch
+
+from astrai.config.preprocess_config import PipelineConfig
+from astrai.preprocessing.core import (
+    build_position_ids,
+    build_preprocessing_components,
+    iter_raw_records,
+    to_per_record_tensors,
+)
+
+
+class TokenizeTransform:
+    """Tokenize raw JSONL record dicts into per-key tensor lists.
+
+    Owns the three preprocessing concerns that were previously inlined in
+    ``JsonlStore``: tokenization, loss-mask construction and position-id
+    generation.  Constructing it loads the tokenizer, so it is intentionally
+    cheap to pass around once built.
+
+    Args:
+        config: Pipeline config describing sections / masks / position mode.
+        tokenizer_path: Path passed to ``AutoTokenizer.from_pretrained``.
+    """
+
+    def __init__(self, config: PipelineConfig, tokenizer_path: str):
+        self.config = config
+        self.tokenizer, self.mask_builder, self.position_strategy = (
+            build_preprocessing_components(config, tokenizer_path)
+        )
+
+    @classmethod
+    def from_config_file(cls, config_path: str) -> "TokenizeTransform":
+        """Build from a ``dataset_config.json`` file path.
+
+        The config file follows :class:`PipelineConfig` schema with an
+        extra ``tokenizer_path`` field.  When omitted, the config's
+        parent directory is used as the tokenizer path.
+        """
+        root = Path(config_path).parent
+        with open(config_path, "r", encoding="utf-8") as f:
+            raw_config = json.load(f)
+        tokenizer_path = raw_config.pop("tokenizer_path", None) or str(root)
+        config = PipelineConfig.from_dict(raw_config)
+        return cls(config, tokenizer_path)
+
+    def apply(self, records: List[dict]) -> Dict[str, list]:
+        """Tokenize a list of raw record dicts.
+
+        Returns a dict mapping key (``sequence``, ``chosen``, ``responses``,
+        …) to a list of per-record tensors (or nested tensor lists for
+        multi-response keys such as GRPO ``responses``).
+        """
+        raw: Dict[str, list] = {}
+        doc_sequences: List[List[int]] = []
+
+        for result in iter_raw_records(
+            records, self.mask_builder, self.config, self.tokenizer
+        ):
+            primary = None
+            for val in result.values():
+                if isinstance(val, list) and val and isinstance(val[0], int):
+                    primary = val
+                    break
+            if primary is not None:
+                doc_sequences.append(primary)
+            for key, ids in result.items():
+                raw.setdefault(key, []).append(ids)
+
+        tensors = to_per_record_tensors(raw)
+
+        pos_ids = build_position_ids(doc_sequences, self.position_strategy)
+        if pos_ids is not None:
+            tensors["position_ids"] = [torch.tensor(pos_ids, dtype=torch.int32)]
+
+        return tensors

astrai/preprocessing/writer.py

@@ -1,7 +1,7 @@
 """Storage writer strategies for pipeline output.
 
 The :class:`StoreWriter` abstraction decouples the pipeline from the
-concrete storage format (bin / h5).  The pipeline builds a ``{key:
+concrete storage format (bin).  The pipeline builds a ``{key:
 List[Tensor]}`` dict and delegates the write to the writer selected
 by ``output.storage_format``.
 """
@@ -15,7 +15,7 @@ from typing import Dict, List
 import torch
 
 from astrai.factory import BaseFactory
-from astrai.serialization import save_bin, save_h5
+from astrai.serialization import save_bin
 
 logger = logging.getLogger(__name__)
 
@@ -54,22 +54,3 @@ class BinWriter(StoreWriter):
                 exc_info=True,
             )
             raise
-
-
-@StoreWriterFactory.register("h5")
-class H5Writer(StoreWriter):
-    def save(self, output_dir, domain, shard_idx, tensors):
-        chunk_dir = os.path.join(output_dir, domain)
-        file_path = os.path.join(chunk_dir, f"data_{shard_idx:04d}.h5")
-        try:
-            save_h5(chunk_dir, f"data_{shard_idx:04d}", tensors)
-        except Exception:
-            if os.path.exists(file_path):
-                os.remove(file_path)
-            logger.error(
-                "Failed to write shard %s/data_%04d.h5, cleaned up partial output",
-                domain,
-                shard_idx,
-                exc_info=True,
-            )
-            raise

astrai/serialization/__init__.py

@@ -19,13 +19,24 @@ from astrai.serialization.checkpoint import (
 )
 from astrai.serialization.dataset import (
     load_bin,
-    load_h5,
+    load_bin_offsets,
     save_bin,
-    save_h5,
+)
+from astrai.serialization.hf_adapter import (
+    HF_MODEL_TYPES,
+    adapt_config,
+    convert_hf_config,
+    convert_hf_weights,
+    looks_like_hf_state_dict,
 )
 
 __all__ = [
     "Checkpoint",
+    "HF_MODEL_TYPES",
+    "adapt_config",
+    "convert_hf_config",
+    "convert_hf_weights",
+    "looks_like_hf_state_dict",
     "load_json",
     "load_model_config",
     "load_model_weights",
@@ -37,7 +48,6 @@ __all__ = [
     "save_safetensors",
     "save_torch",
     "load_bin",
-    "load_h5",
+    "load_bin_offsets",
     "save_bin",
-    "save_h5",
 ]

astrai/serialization/checkpoint.py

@@ -5,7 +5,7 @@ import json
 import time
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Any, Dict, Optional, Union
+from typing import Any, Callable, Dict, Optional, Union
 
 import safetensors.torch as st
 import torch
@@ -22,39 +22,31 @@ def save_safetensors(state_dict: dict, path: Union[str, Path]):
     st.save_file(state_dict, str(path))
 
 
-def load_safetensors(path: Union[str, Path], broadcast: bool = False) -> dict:
+def _broadcast_load(loader: Callable[[], dict], broadcast: bool) -> dict:
+    """Load on rank 0 and broadcast the object to all ranks."""
     if not broadcast or not dist.is_initialized():
-        return st.load_file(str(path))
-
+        return loader()
     rank = get_rank()
     if rank == 0:
-        state_dict = st.load_file(str(path))
+        data = loader()
     else:
-        state_dict = {}
-    tmp = [state_dict]
+        data = {}
+    tmp = [data]
     dist.broadcast_object_list(tmp, src=0)
     return tmp[0]
 
 
+def load_safetensors(path: Union[str, Path], broadcast: bool = False) -> dict:
+    return _broadcast_load(lambda: st.load_file(str(path)), broadcast)
+
+
 def save_json(data: dict, path: Union[str, Path]):
     with open(str(path), "w") as f:
         json.dump(data, f, indent=2)
 
 
 def load_json(path: Union[str, Path], broadcast: bool = False) -> dict:
-    if not broadcast or not dist.is_initialized():
-        with open(str(path), "r") as f:
-            return json.load(f)
-
-    rank = get_rank()
-    if rank == 0:
-        with open(str(path), "r") as f:
-            data = json.load(f)
-    else:
-        data = {}
-    tmp = [data]
-    dist.broadcast_object_list(tmp, src=0)
-    return tmp[0]
+    return _broadcast_load(lambda: json.loads(Path(path).read_text()), broadcast)
 
 
 def save_torch(obj: Any, path: Union[str, Path]):
@@ -99,7 +91,21 @@ def load_model_config(save_directory: str) -> dict:
 
 
 def load_model_weights(save_directory: str) -> dict:
-    return load_state_dict(Path(save_directory) / _WEIGHTS_FILE)
+    save_path = Path(save_directory)
+    weights_file = save_path / _WEIGHTS_FILE
+    if weights_file.exists():
+        return load_state_dict(weights_file)
+
+    index_path = save_path / "model.safetensors.index.json"
+    if index_path.exists():
+        index = load_json(index_path)
+        weight_map = index.get("weight_map", {})
+        state_dict = {}
+        for shard in sorted(set(weight_map.values())):
+            state_dict.update(load_state_dict(save_path / shard))
+        return state_dict
+
+    raise FileNotFoundError(f"No model weights found in {save_directory}")
 
 
 def load_state_dict(path: Union[str, Path], broadcast: bool = False) -> dict:
@@ -190,8 +196,10 @@ class Checkpoint:
         if meta_path.exists():
             return cls.load(save_dir, broadcast=broadcast)
 
-        if weights_path.exists():
-            state_dict = load_state_dict(weights_path, broadcast=broadcast)
+        weights_path = save_path / _WEIGHTS_FILE
+        index_path = save_path / "model.safetensors.index.json"
+        if weights_path.exists() or index_path.exists():
+            state_dict = load_model_weights(save_dir)
             config = {}
             config_path = save_path / _CONFIG_FILE
             if config_path.exists():

astrai/serialization/dataset.py

@@ -1,61 +1,51 @@
-"""Dataset storage serialization helpers (HDF5 / memory-mapped binary)."""
+"""Dataset storage serialization helpers (memory-mapped binary)."""
 
 import json
 import os
-from pathlib import Path
-from typing import Dict, List
+from typing import Any, Dict, List, Optional
 
-import h5py
 import numpy as np
 import torch
 from torch import Tensor
 
 
-def save_h5(file_path: str, file_name: str, tensor_group: Dict[str, List[Tensor]]):
-    os.makedirs(file_path, exist_ok=True)
-    full_file_path = os.path.join(file_path, f"{file_name}.h5")
-    with h5py.File(full_file_path, "w") as f:
-        for key, tensors in tensor_group.items():
-            grp = f.create_group(key)
-            for idx, tensor in enumerate(tensors):
-                arr = tensor.cpu().numpy()
-                grp.create_dataset(f"data_{idx}", data=arr)
-
-
-def load_h5(file_path: str, share_memory=True) -> Dict[str, List[Tensor]]:
-    tensor_group: Dict[str, List[Tensor]] = {}
-
-    root_path = Path(file_path)
-    if root_path.is_file() and root_path.suffix in (".h5", ".hdf5"):
-        h5_files = [root_path]
-    else:
-        h5_files = list(root_path.rglob("*.h5")) + list(root_path.rglob("*.hdf5"))
-
-    for h5_file in h5_files:
-        with h5py.File(h5_file, "r") as f:
-            for key in f.keys():
-                grp = f[key]
-                dsets = []
-                for dset_name in grp.keys():
-                    dset = grp[dset_name]
-                    tensor = torch.from_numpy(dset[:])
-                    if share_memory:
-                        tensor = tensor.share_memory_()
-                    dsets.append(tensor)
-
-                if tensor_group.get(key) is None:
-                    tensor_group[key] = []
-                tensor_group[key].extend(dsets)
-
-    return tensor_group
-
-
-def save_bin(file_path: str, tensor_group: Dict[str, List[Tensor]]):
+def save_bin(
+    file_path: str,
+    tensor_group: Dict[str, List[Tensor]],
+    record_keys: Optional[List[str]] = None,
+):
+    """Save tensors as memory-mapped binary files.
+
+    When *record_keys* is provided, those keys are written with per-record
+    cumulative offsets in ``meta.json`` so that ``MmapStore.fetch_record``
+    can slice individual records from the concatenated binary without
+    cross-record concatenation.  Keys not in *record_keys* (e.g. SEQ
+    ``sequence``) are written as a single contiguous stream without
+    offsets, preserving backward compatibility.
+
+    Nested keys (``List[List[Tensor]]`` such as GRPO ``responses``) are
+    not supported in bin format — use JSONL for those.
+    """
     os.makedirs(file_path, exist_ok=True)
+    record_keys = set(record_keys or [])
     meta = {}
     for key, tensors in tensor_group.items():
+        if tensors and isinstance(tensors[0], list):
+            raise ValueError(
+                f"Nested key '{key}' (List[List[Tensor]]) is not supported "
+                f"in bin format. Use JSONL storage instead."
+            )
         cat = torch.cat(tensors, dim=0)
-        meta[key] = {"shape": list(cat.shape), "dtype": str(cat.dtype).split(".")[-1]}
+        entry: Dict[str, Any] = {
+            "shape": list(cat.shape),
+            "dtype": str(cat.dtype).split(".")[-1],
+        }
+        if key in record_keys:
+            offsets = [0]
+            for t in tensors:
+                offsets.append(offsets[-1] + t.shape[0])
+            entry["offsets"] = offsets
+        meta[key] = entry
         np.asarray(cat.cpu().numpy()).tofile(os.path.join(file_path, f"{key}.bin"))
     with open(os.path.join(file_path, "meta.json"), "w") as f:
         json.dump(meta, f)
@@ -69,8 +59,24 @@ def load_bin(file_path: str) -> Dict[str, List[Tensor]]:
         arr = np.memmap(
             os.path.join(file_path, f"{key}.bin"),
             dtype=info["dtype"],
-            mode="r+",
+            mode="c",
             shape=tuple(info["shape"]),
         )
         segments[key] = [torch.from_numpy(arr)]
     return segments
+
+
+def load_bin_offsets(file_path: str) -> Dict[str, List[int]]:
+    """Read per-record cumulative offsets from ``meta.json``.
+
+    Returns an empty dict when no key has offsets (legacy bin files),
+    in which case record-mode access falls back to per-record segment
+    indexing (JSONL layout).
+    """
+    with open(os.path.join(file_path, "meta.json"), "r") as f:
+        meta = json.load(f)
+    offsets: Dict[str, List[int]] = {}
+    for key, info in meta.items():
+        if "offsets" in info:
+            offsets[key] = info["offsets"]
+    return offsets

astrai/serialization/hf_adapter.py

@@ -0,0 +1,271 @@
+"""HuggingFace checkpoint adaptation for LLaMA-style decoder models.
+
+AstrAI stores weights with its own key names (``layers.<i>.input_norm``,
+``layers.<i>.mlp.gate``), while HuggingFace decoder-only checkpoints use
+``model.layers.<i>.input_layernorm`` / ``model.layers.<i>.mlp.gate_proj``.
+This module translates HF configs and state dicts so external checkpoints
+can be loaded directly.
+
+Supported families (LLaMA layout, dense and MoE):
+- dense FFN: llama, mistral, qwen2, gemma, gemma2, phi3
+- MoE FFN (Mixtral / Qwen2-MoE / DeepSeek-V3 layout): router
+  ``mlp.gate``, routed experts ``mlp.experts.<j>``, shared experts
+  ``mlp.shared_experts.<j>``
+
+Not supported:
+- MLA attention (DeepSeek-V2/V3 ``kv_a_proj_with_mqa``) uses a different
+  KV factorization and cannot be converted numerically.
+- Attention/MLP bias (``attention_bias`` / ``mlp_bias``) — AstrAI
+  projections are bias-free.
+"""
+
+import logging
+import re
+from typing import Any, Dict, Mapping
+
+import torch
+
+from astrai.config.base import BaseConfig
+
+logger = logging.getLogger(__name__)
+
+HF_MODEL_TYPES = frozenset(
+    {
+        "llama",
+        "mistral",
+        "mixtral",
+        "qwen2",
+        "qwen2_moe",
+        "gemma",
+        "gemma2",
+        "phi3",
+    }
+)
+
+_EMBED = re.compile(r"^model\.embed_tokens\.weight$")
+_ATTN = re.compile(r"^model\.layers\.(\d+)\.self_attn\.(q|k|v|o)_proj\.(weight|bias)$")
+_Q_NORM = re.compile(r"^model\.layers\.(\d+)\.self_attn\.q_norm\.weight$")
+_K_NORM = re.compile(r"^model\.layers\.(\d+)\.self_attn\.k_norm\.weight$")
+_INPUT_NORM = re.compile(r"^model\.layers\.(\d+)\.input_layernorm\.weight$")
+_POST_NORM = re.compile(r"^model\.layers\.(\d+)\.post_attention_layernorm\.weight$")
+_FINAL_NORM = re.compile(r"^model\.norm\.weight$")
+_LM_HEAD = re.compile(r"^lm_head\.weight$")
+_DENSE_MLP = re.compile(
+    r"^model\.layers\.(\d+)\.mlp\.(gate|up|down)_proj\.(weight|bias)$"
+)
+_MOE_ROUTER = re.compile(r"^model\.layers\.(\d+)\.mlp\.gate\.weight$")
+_MOE_EXPERTS = re.compile(
+    r"^model\.layers\.(\d+)\.mlp\.experts\.(\d+)\.(gate|up|down)_proj\.(weight|bias)$"
+)
+_MOE_SHARED = re.compile(
+    r"^model\.layers\.(\d+)\.mlp\.shared_expert(?:s)?\.(\d+)\."
+    r"(gate|up|down)_proj\.(weight|bias)$"
+)
+
+_ASTR_PREFIXES = ("embed_tokens.", "layers.", "norm.", "lm_head.")
+
+
+def looks_like_hf_state_dict(state_dict: Mapping[str, Any]) -> bool:
+    """Return True if *state_dict* uses HuggingFace key names."""
+    return any(
+        key.startswith("model.")
+        or "self_attn." in key
+        or "input_layernorm" in key
+        or "mlp.experts." in key
+        for key in state_dict
+    )
+
+
+def _is_dense_mlp_layer(config: BaseConfig, layer_id: int) -> bool:
+    """Return whether a layer uses dense MLP instead of routed experts."""
+    if getattr(config, "ffn_type", "mlp") != "moe":
+        return True
+    mlp_only = getattr(config, "mlp_only_layers", None) or []
+    if layer_id in mlp_only:
+        return True
+    step = getattr(config, "decoder_sparse_step", 1) or 1
+    return step > 1 and (layer_id + 1) % step != 0
+
+
+def adapt_config(raw: Dict[str, Any]) -> Dict[str, Any]:
+    """Translate *raw* for AstrAI if it looks like an HF model config."""
+    if raw.get("model_type") in HF_MODEL_TYPES:
+        return convert_hf_config(raw)
+    return raw
+
+
+def convert_hf_config(raw: Dict[str, Any]) -> Dict[str, Any]:
+    """Convert an HF LLaMA-style config dict to AstrAI field names."""
+    if raw.get("attention_bias") or raw.get("mlp_bias"):
+        raise NotImplementedError(
+            "attention_bias / mlp_bias checkpoints are not supported; "
+            "AstrAI projections are bias-free"
+        )
+
+    cfg: Dict[str, Any] = {}
+    for key in (
+        "vocab_size",
+        "hidden_size",
+        "num_hidden_layers",
+        "intermediate_size",
+        "rms_norm_eps",
+        "tie_word_embeddings",
+        "max_position_embeddings",
+        "rope_theta",
+        "rope_scaling",
+        "num_attention_heads",
+        "num_key_value_heads",
+        "use_qk_norm",
+        "use_gated_attention",
+        "kv_lora_rank",
+        "qk_nope_head_dim",
+        "qk_rope_head_dim",
+        "moe_intermediate_size",
+        "shared_expert_intermediate_size",
+        "topk_method",
+        "norm_topk_prob",
+        "moe_aux_loss_coef",
+        "decoder_sparse_step",
+        "mlp_only_layers",
+        "neftune_alpha",
+    ):
+        if key in raw:
+            cfg[key] = raw[key]
+
+    if "qk_norm" in raw and "use_qk_norm" not in cfg:
+        cfg["use_qk_norm"] = raw["qk_norm"]
+    if (
+        raw.get("model_type") in ("gemma", "gemma2")
+        and "use_qk_norm" not in cfg
+        and "qk_norm" not in raw
+    ):
+        # Gemma/Gemma2 always apply RMSNorm to Q and K before attention.
+        cfg["use_qk_norm"] = True
+
+    n_heads = raw.get("num_attention_heads")
+    if cfg.get("num_key_value_heads") is None and n_heads is not None:
+        cfg["num_key_value_heads"] = n_heads
+
+    if raw.get("head_dim") is not None and n_heads and raw.get("hidden_size"):
+        expected = raw["hidden_size"] // n_heads
+        if raw["head_dim"] != expected:
+            raise NotImplementedError(
+                f"HF head_dim={raw['head_dim']} differs from the computed "
+                f"head dim {expected}; AstrAI derives head_dim from "
+                "hidden_size / num_attention_heads"
+            )
+
+    if "kv_lora_rank" in raw:
+        cfg["attn_type"] = "mla"
+
+    n_experts = raw.get("num_local_experts") or raw.get("n_routed_experts")
+    if n_experts:
+        cfg["ffn_type"] = "moe"
+        cfg["n_routed_experts"] = n_experts
+        if "num_experts_per_tok" in raw:
+            cfg["n_activated_experts"] = raw["num_experts_per_tok"]
+        if "n_activated_experts" in raw:
+            cfg["n_activated_experts"] = raw["n_activated_experts"]
+        if "n_shared_experts" in raw:
+            cfg["n_shared_experts"] = raw["n_shared_experts"]
+        else:
+            # Mixtral has no shared experts; AstrAI defaults to one.
+            cfg["n_shared_experts"] = 0
+        if cfg.get("moe_intermediate_size") is None and "intermediate_size" in raw:
+            # MoE configs store the per-expert FFN size in intermediate_size.
+            cfg["moe_intermediate_size"] = raw["intermediate_size"]
+        first_k_dense = raw.get("first_k_dense_replace")
+        if isinstance(first_k_dense, int) and first_k_dense > 0:
+            cfg["mlp_only_layers"] = list(range(first_k_dense))
+            cfg["decoder_sparse_step"] = 1
+
+    cfg["model_type"] = "autoregressive_lm"
+    return cfg
+
+
+def convert_hf_weights(
+    state_dict: Mapping[str, Any],
+    config: BaseConfig,
+) -> Dict[str, torch.Tensor]:
+    """Rename HF state dict keys to AstrAI names.
+
+    Keys that are already AstrAI-style pass through unchanged; unmapped
+    HF keys are dropped with a warning. Use with ``strict=True`` to fail
+    loudly when the checkpoint does not match the config.
+    """
+    if getattr(config, "attn_type", "gqa") == "mla":
+        if any("kv_a_proj_with_mqa" in key for key in state_dict):
+            raise NotImplementedError(
+                "MLA attention (DeepSeek-V2/V3 kv_a_proj_with_mqa) uses a "
+                "different KV factorization and cannot be converted"
+            )
+
+    ffn_type = getattr(config, "ffn_type", "mlp")
+    converted: Dict[str, torch.Tensor] = {}
+    skipped: list[str] = []
+    for key, tensor in state_dict.items():
+        if key.startswith(_ASTR_PREFIXES):
+            converted[key] = tensor
+            continue
+
+        new_key = None
+        if ffn_type == "moe":
+            m = _MOE_ROUTER.match(key)
+            if m:
+                new_key = f"layers.{m.group(1)}.mlp.router.weight"
+            else:
+                m = _MOE_EXPERTS.match(key)
+                if m:
+                    new_key = (
+                        f"layers.{m.group(1)}.mlp.routed_experts.{m.group(2)}."
+                        f"{m.group(3)}.{m.group(4)}"
+                    )
+                else:
+                    m = _MOE_SHARED.match(key)
+                    if m:
+                        new_key = (
+                            f"layers.{m.group(1)}.mlp.shared_experts.{m.group(2)}."
+                            f"{m.group(3)}.{m.group(4)}"
+                        )
+            if new_key is None:
+                m = _DENSE_MLP.match(key)
+                if m and _is_dense_mlp_layer(config, int(m.group(1))):
+                    new_key = f"layers.{m.group(1)}.mlp.{m.group(2)}.{m.group(3)}"
+        else:
+            m = _DENSE_MLP.match(key)
+            if m:
+                new_key = f"layers.{m.group(1)}.mlp.{m.group(2)}.{m.group(3)}"
+
+        if new_key is None:
+            m = _ATTN.match(key)
+            if m:
+                new_key = (
+                    f"layers.{m.group(1)}.attention.{m.group(2)}_proj.{m.group(3)}"
+                )
+            elif (m := _Q_NORM.match(key)) is not None:
+                new_key = f"layers.{m.group(1)}.attention.q_norm.weight"
+            elif (m := _K_NORM.match(key)) is not None:
+                new_key = f"layers.{m.group(1)}.attention.k_norm.weight"
+            elif (m := _INPUT_NORM.match(key)) is not None:
+                new_key = f"layers.{m.group(1)}.input_norm.weight"
+            elif (m := _POST_NORM.match(key)) is not None:
+                new_key = f"layers.{m.group(1)}.post_attention_norm.weight"
+            elif (m := _EMBED.match(key)) is not None:
+                new_key = "embed_tokens.weight"
+            elif (m := _FINAL_NORM.match(key)) is not None:
+                new_key = "norm.weight"
+            elif (m := _LM_HEAD.match(key)) is not None:
+                new_key = "lm_head.weight"
+
+        if new_key is None:
+            skipped.append(key)
+        else:
+            converted[new_key] = tensor
+
+    if skipped:
+        logger.warning(
+            "Dropped %d unmapped HuggingFace weight key(s): %s",
+            len(skipped),
+            ", ".join(sorted(skipped)[:10]),
+        )
+    return converted

astrai/signal_handler.py

@@ -0,0 +1,53 @@
+import logging
+import os
+import signal
+import threading
+
+logger = logging.getLogger(__name__)
+
+_early_stop = threading.Event()
+_active_context = None
+
+
+def _early_handler(signum: int, frame):
+    sig = signal.Signals(signum)
+    logger.warning(
+        "Received %s (pid=%d), requesting graceful training stop...",
+        sig.name,
+        os.getpid(),
+    )
+    _early_stop.set()
+    if _active_context is not None:
+        _active_context.request_stop()
+
+
+def install_early_signal_handlers():
+    for sig in (signal.SIGTERM, signal.SIGINT):
+        signal.signal(sig, _early_handler)
+    _unblock_signals()
+
+
+def _unblock_signals():
+    try:
+        mask = signal.pthread_sigmask(signal.SIG_BLOCK, set())
+        blocked = {signal.SIGTERM, signal.SIGINT} & mask
+        if blocked:
+            signal.pthread_sigmask(signal.SIG_UNBLOCK, blocked)
+    except (AttributeError, OSError):
+        pass
+
+
+def register_signal_handlers(context):
+    global _active_context
+    _active_context = context
+    for sig in (signal.SIGTERM, signal.SIGINT):
+        signal.signal(sig, _early_handler)
+    if _early_stop.is_set():
+        context.request_stop()
+        logger.warning("Signal was received during initialization, stopping...")
+
+
+def unregister_signal_handlers():
+    global _active_context
+    _active_context = None
+    _early_stop.clear()

astrai/tokenize/__init__.py

@@ -1,8 +1,10 @@
 from astrai.tokenize.chat_template import ChatTemplate, MessageType
-from astrai.tokenize.tokenizer import AutoTokenizer
+from astrai.tokenize.tokenizer import AutoTokenizer, Message, Messages
 
 __all__ = [
     "AutoTokenizer",
     "ChatTemplate",
     "MessageType",
+    "Message",
+    "Messages",
 ]

astrai/tokenize/chat_template.py

@@ -1,3 +1,4 @@
+from functools import cached_property
 from typing import Any, Dict, List, Optional
 
 from jinja2 import Template
@@ -29,7 +30,34 @@ class ChatTemplate:
         self.description = description
         self.default_variables = default_variables or {}
         self.special_tokens = special_tokens or {}
-        self._compiled: Template = Template(template_str)
+
+    @cached_property
+    def _compiled(self) -> Template:
+        """Lazy-compiled Jinja2 template, cached on first access.
+
+        The compiled :class:`~jinja2.Template` holds a dynamically-generated
+        ``root`` render function whose ``__module__`` is ``None``; under
+        ``pickle`` it falls back to ``__main__`` and breaks ``spawn``-based
+        multiprocessing.  :meth:`__getstate__` drops the cached template so
+        that pickle serialises only ``template_str``; each worker rebuilds
+        the cache on first render.
+        """
+        return Template(self.template_str)
+
+    def __getstate__(self) -> Dict[str, Any]:
+        """Exclude the cached Jinja2 template from pickling.
+
+        ``Template.root_render_func`` is a dynamically generated closure
+        that cannot be pickled by reference.  Dropping ``_compiled`` here
+        lets :class:`cached_property` rebuild it on first access after
+        unpickle.
+        """
+        state = self.__dict__.copy()
+        state.pop("_compiled", None)
+        return state
+
+    def __setstate__(self, state: Dict[str, Any]) -> None:
+        self.__dict__.update(state)
 
     @classmethod
     def from_string(

astrai/tokenize/tokenizer.py

@@ -10,12 +10,16 @@ from tokenizers import Tokenizer
 
 from astrai.tokenize.chat_template import ChatTemplate
 
+Message = Dict[str, str]
+"""Single chat message with ``role`` and ``content`` keys."""
+
+Messages = List[Message]
+"""Single conversation — a list of messages."""
+
 
 class AutoTokenizer:
     """Base tokenizer class with automatic loading support"""
 
-    TOKENIZER_CLASSES = {}  # Registry for auto-loading
-
     def __init__(
         self,
         path: Optional[Union[str, Path]] = None,
@@ -102,17 +106,6 @@ class AutoTokenizer:
         with open(save_path / "tokenizer_config.json", "w", encoding="utf-8") as f:
             json.dump(config, f, ensure_ascii=False, indent=2)
 
-    @classmethod
-    def register_tokenizer(cls, name: str, tokenizer_class: type):
-        """
-        Register a new tokenizer class.
-
-        Args:
-            name: Name to register the tokenizer class under
-            tokenizer_class: The tokenizer class to register
-        """
-        cls.TOKENIZER_CLASSES[name] = tokenizer_class
-
     def encode(
         self,
         tokens: Union[str, List[str]],
@@ -120,7 +113,16 @@ class AutoTokenizer:
         is_pretokenized: bool = False,
         add_special_tokens: bool = True,
     ) -> List:
-        """Encode text to tokens or token IDs."""
+        """Encode text to token IDs.
+
+        Accepts both single strings and batches:
+
+        - ``encode("hello")`` → ``[123, 456]``
+        - ``encode(["hello", "world"])`` → ``[[123, 456], [789]]``
+
+        Batches are tokenised in parallel via the Rust backend's
+        ``encode_batch`` (uses all available CPU cores).
+        """
         if self._tokenizer is None:
             raise RuntimeError(
                 "Tokenizer not initialized. Load or create a tokenizer first."
@@ -133,15 +135,13 @@ class AutoTokenizer:
                 add_special_tokens=add_special_tokens,
             )
             return encoded.ids if out_ids else encoded.tokens
-        else:
-            encoded_list = self._tokenizer.encode_batch(
-                tokens,
-                is_pretokenized=is_pretokenized,
-                add_special_tokens=add_special_tokens,
-            )
-            return [
-                encoded.ids if out_ids else encoded.tokens for encoded in encoded_list
-            ]
+
+        encoded_list = self._tokenizer.encode_batch(
+            tokens,
+            is_pretokenized=is_pretokenized,
+            add_special_tokens=add_special_tokens,
+        )
+        return [encoded.ids if out_ids else encoded.tokens for encoded in encoded_list]
 
     def decode(self, tokens: List[int], skip_special_tokens: bool = True) -> str:
         """Decode token IDs to text."""
@@ -164,7 +164,14 @@ class AutoTokenizer:
           - tokenizer.bos_token   → returns string
           - tokenizer.bos_token_id → returns corresponding integer ID
           - tokenizer.stop_ids → returns list of corresponding integer IDs for all special tokens
+
+        Internal/private attrs are not intercepted: during unpickle
+        ``__dict__`` is empty, so probing ``self._special_token_map``
+        would recurse infinitely.
         """
+        if key.startswith("_"):
+            raise AttributeError(key)
+
         # Handle stop_ids - return IDs for all special tokens
         if key == "stop_ids":
             stop_ids = []
@@ -220,45 +227,63 @@ class AutoTokenizer:
 
     def apply_chat_template(
         self,
-        messages: List[Dict[str, str]],
+        messages: Union[Messages, List[Messages]],
         system_prompt: Optional[str] = None,
         tokenize: bool = True,
         add_generation_prompt: bool = True,
         **kwargs,
-    ) -> Union[str, List[int]]:
-        """
-        Apply the chat template to messages and optionally tokenize the result.
+    ) -> Union[str, List[int], List[str], List[List[int]]]:
+        """Apply the chat template and optionally tokenize.
+
+        Accepts both single conversations and batches:
+
+        - ``apply_chat_template([msg1, msg2])`` → ``"..."`` or ``[ids]``
+        - ``apply_chat_template([[msg1, msg2], [msg3]])`` → ``["..", ".."]``
+          or ``[[ids], [ids]]``
+
+        Batches render each conversation list and tokenise all at once via
+        :meth:`encode` (``List[str]`` → Rust parallel ``encode_batch``).
 
         Args:
-            messages: List of message dicts with 'role' and 'content'.
-            system_prompt: Optional system prompt string (auto-converted to first message).
+            messages: Single conversation (``Messages``) or batch of
+                conversations (``BatchMessages``).
+            system_prompt: Optional system prompt prepended (single mode only).
             tokenize: Whether to return token IDs (True) or raw string (False).
-            add_generation_prompt: Whether to add the generation prompt (default: True).
-            **kwargs: Additional variables to pass to the template.
+            add_generation_prompt: Whether to add the generation prompt.
+            **kwargs: Additional template variables.
 
         Returns:
-            Either the rendered string or list of token IDs.
-
-        Raises:
-            RuntimeError: If chat template is not set.
+            Single mode: ``str`` or ``List[int]``.
+            Batch mode: ``List[str]`` or ``List[List[int]]``.
         """
         if self._chat_template is None:
             raise RuntimeError(
                 "Chat template not set. Use set_chat_template() to set a template first."
             )
 
-        # Auto-convert system_prompt to first message if provided
+        is_batch = bool(messages) and isinstance(messages[0], list)
+
+        if is_batch:
+            rendered = [
+                self._chat_template.render(
+                    messages=msgs,
+                    add_generation_prompt=add_generation_prompt,
+                    **kwargs,
+                )
+                for msgs in messages
+            ]
+            if tokenize:
+                return self.encode(rendered)  # List[str] → batch encode
+            return rendered
+
+        # Single conversation
         if system_prompt:
             messages = [{"role": "system", "content": system_prompt}] + list(messages)
-
-        # Render the template
         rendered = self._chat_template.render(
             messages=messages,
             add_generation_prompt=add_generation_prompt,
             **kwargs,
         )
-
         if tokenize:
             return self.encode(rendered)
-
         return rendered

astrai/trainer/metric_util.py

@@ -1,3 +1,4 @@
+import math
 from typing import Dict
 
 import torch
@@ -22,6 +23,54 @@ def grad_norm(model: nn.Module, per_param: bool = False) -> float | Dict[str, fl
     return total_sq.sqrt().item()
 
 
+class GradSNRTracker:
+    """Track gradient signal-to-noise ratio via EMA of first/second moments.
+
+    SNR = E[g]^2 / Var(g) = E[g]^2 / (E[g^2] - E[g]^2)
+
+    The reported value is the power ratio in decibels: ``10 * log10(SNR)``.
+
+    The tracker accumulates per-parameter EMA moments across optimizer steps.
+    Call ``update`` after backward (before ``optimizer.step``) and read
+    ``snr`` to get the aggregate SNR across all parameters.
+    """
+
+    def __init__(self, beta: float = 0.999, eps: float = 1e-8):
+        self.beta = beta
+        self.eps = eps
+        self._first: Dict[int, torch.Tensor] = {}
+        self._second: Dict[int, torch.Tensor] = {}
+
+    @torch.no_grad()
+    def update(self, model: nn.Module) -> None:
+        beta = self.beta
+        for param in model.parameters():
+            if param.grad is None:
+                continue
+            pid = id(param)
+            g = param.grad.detach()
+            if pid not in self._first:
+                self._first[pid] = g.clone()
+                self._second[pid] = g.pow(2).clone()
+            else:
+                self._first[pid].mul_(beta).add_(g, alpha=1 - beta)
+                self._second[pid].mul_(beta).addcmul_(g, g, value=1 - beta)
+
+    @property
+    def snr(self) -> float:
+        if not self._first:
+            return 0.0
+        total_signal = 0.0
+        total_noise = 0.0
+        for m, v in zip(self._first.values(), self._second.values()):
+            signal = m.pow(2).sum().item()
+            noise = (v - m.pow(2)).clamp(min=0).sum().item()
+            total_signal += signal
+            total_noise += noise
+        snr = total_signal / (total_noise + self.eps)
+        return 10.0 * math.log10(max(snr, self.eps))
+
+
 def ctx_get_loss(ctx):
     return ctx.loss
 
@@ -36,3 +85,14 @@ def ctx_get_val_loss(ctx):
 
 def ctx_get_grad_norm(ctx):
     return ctx.grad_norm
+
+
+def ctx_get_grad_snr(ctx):
+    tracker = getattr(ctx, "grad_snr_tracker", None)
+    if tracker is None:
+        return None
+    return tracker.snr
+
+
+def ctx_get_moe_metric(ctx, key):
+    return ctx.strategy._moe_metrics.get(key)

astrai/trainer/rollout.py

@@ -0,0 +1,421 @@
+"""Online rollout runner for RL training.
+
+Provides:
+- :class:`RawRollout` — generation output container (no reward yet)
+- :class:`RolloutResult` — a :class:`RawRollout` with rewards attached
+- :class:`BaseRewardModel` — pluggable reward interface
+- :class:`RolloutGenerator` — KV-cache-backed generation of grouped
+  responses + decoding (no reward); delegates the generation loop to
+  :class:`~astrai.inference.scheduler.InferenceScheduler.run_batch`
+  so rollout and the production inference server share one code path
+- :class:`RolloutRunner` — orchestrates generation + scoring with a
+  step-driven cache; its ``__call__`` returns ``(RolloutResult, is_fresh)``
+  so callers do not need to rely on object identity to detect refreshes.
+"""
+
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+from typing import Dict, List, Optional, Tuple
+
+import torch
+from torch import Tensor
+
+from astrai.inference.scheduler import InferenceScheduler
+
+
+@dataclass(kw_only=True)
+class RawRollout:
+    """Generation output before reward scoring.
+
+    Produced by :class:`RolloutGenerator`; consumed by :class:`RolloutRunner`
+    to assemble a :class:`RolloutResult` once rewards are attached.
+
+    Fields are designed to cover all common RL algorithms:
+    GRPO, PPO, Online DPO, Rejection Sampling, etc.
+
+    Fields:
+        prompts: Tokenized prompts, shape ``[B, P_len]``.
+        prompt_mask: Boolean mask for real prompt tokens, shape ``[B, P_len]``.
+        responses: Generated response token IDs, shape ``[B, G, R_max]``.
+        response_mask: Boolean mask for real (non-pad) response tokens,
+            shape ``[B, G, R_max]``.
+        logprobs_old: Per-token log-probs under the behaviour policy,
+            shape ``[B, G, R_max]``.
+        prompt_texts: Decoded prompt strings (for reward models that
+            need text).
+        response_texts: Decoded response strings, shape ``[B, G]``
+            (for reward models).
+    """
+
+    prompts: Tensor
+    prompt_mask: Tensor
+    responses: Tensor
+    response_mask: Tensor
+    logprobs_old: Tensor
+    prompt_texts: List[str] = field(default_factory=list)
+    response_texts: List[List[str]] = field(default_factory=list)
+
+
+@dataclass(kw_only=True)
+class RolloutResult(RawRollout):
+    """A :class:`RawRollout` with reward scoring attached.
+
+    Produced by :class:`RolloutRunner` once the :class:`BaseRewardModel`
+    has scored the decoded responses.
+
+    Fields:
+        rewards: Reward per response, shape ``[B, G]``.
+    """
+
+    rewards: Tensor
+
+
+class BaseRewardModel(ABC):
+    """Pluggable reward model interface.
+
+    Subclasses should implement ``score()`` to return a ``[B, G]`` float
+    tensor of rewards.  Implementations can be:
+    * A loaded reward model (e.g. ArmoRM, Skywork-Reward)
+    * An external API call
+    * A rule-based function (format, length, keyword matching)
+    """
+
+    @abstractmethod
+    def score(self, prompts: List[str], responses: List[List[str]]) -> Tensor:
+        """Score each generated response.
+
+        Args:
+            prompts: Raw prompt strings, length ``B``.
+            responses: Generated response strings, shape ``[B, G]``.
+
+        Returns:
+            Float tensor of shape ``[B, G]``.
+        """
+        ...
+
+
+_PAD = 0
+
+
+class RolloutGenerator:
+    """Pure generation + decoding for a group of responses per prompt.
+
+    Delegates the prefill/decode loop to
+    :meth:`~astrai.inference.scheduler.InferenceScheduler.run_batch`,
+    which uses a real KV cache (no O(n²) recompute).  Has no dependency
+    on any reward model; can be reused in isolation for offline
+    generation, qualitative sampling, or eval pipelines.
+    """
+
+    def __init__(
+        self,
+        scheduler: InferenceScheduler,
+        tokenizer,
+        max_tokens: int = 1024,
+        group_size: int = 8,
+        temperature: float = 1.0,
+        top_k: int = 0,
+        top_p: float = 1.0,
+        frequency_penalty: float = 0.0,
+        rep_window: int = 64,
+    ):
+        self.scheduler = scheduler
+        self.tokenizer = tokenizer
+        self.max_tokens = max_tokens
+        self.group_size = group_size
+        self.temperature = temperature
+        self.top_k = top_k
+        self.top_p = top_p
+        self.frequency_penalty = frequency_penalty
+        self.rep_window = rep_window
+
+    @torch.no_grad()
+    def generate(self, batch: Dict) -> RawRollout:
+        """Expand prompts by ``group_size`` and generate one response each.
+
+        Accepted batch formats (per sample, repeated B times):
+
+        - **messages**: ``{"messages": [{"role": "user", "content": "..."}, ...]}``
+        - **instruction + input + output**: ``{"instruction": "...",
+          "input": "...", "output": "..."}`` — mapped to ``system`` /
+          ``user`` / ``assistant`` messages; ``input`` and ``output``
+          are optional and skipped when empty.
+
+        Both are rendered through the tokenizer's chat template with
+        ``add_generation_prompt=True`` so rollout prompts match the
+        format the policy was SFT-trained on.
+        """
+        model = self.scheduler._executor.model
+        was_training = model.training
+        model.eval()
+        try:
+            return self._generate_eval(batch)
+        finally:
+            model.train(was_training)
+
+    def _generate_eval(self, batch: Dict) -> RawRollout:
+        prompt_texts, flat_prompt_ids = self._prepare_prompts(batch)
+        B = len(prompt_texts)
+        G = self.group_size
+        # Re-expand flat list to G copies per prompt for run_batch.
+        expanded_prompt_ids: List[List[int]] = []
+        for ids in flat_prompt_ids:
+            expanded_prompt_ids.extend([list(ids)] * G)
+
+        results = self.scheduler.run_batch(
+            expanded_prompt_ids,
+            max_tokens=self.max_tokens,
+            temperature=self.temperature,
+            top_k=self.top_k,
+            top_p=self.top_p,
+            frequency_penalty=self.frequency_penalty,
+            rep_window=self.rep_window,
+            return_logprobs=True,
+        )
+        if len(results) != B * G:
+            raise RuntimeError(
+                f"Rollout scheduler returned {len(results)} results, expected {B * G}"
+            )
+        for token_ids, logprobs in results:
+            if len(token_ids) != len(logprobs):
+                raise RuntimeError(
+                    "Rollout scheduler returned misaligned token IDs and logprobs"
+                )
+
+        # Each element is (token_ids, logprobs); pad to max length.
+        max_len = 0
+        for token_ids, _lp in results:
+            max_len = max(max_len, len(token_ids))
+        max_len = max(max_len, 1)
+
+        device = self.scheduler.device
+        P_len = max(len(ids) for ids in flat_prompt_ids)
+        prompts_tensor = torch.zeros(B, P_len, dtype=torch.long, device=device)
+        prompt_mask = torch.zeros(B, P_len, dtype=torch.bool, device=device)
+        for i, ids in enumerate(flat_prompt_ids):
+            prompts_tensor[i, -len(ids) :] = torch.tensor(
+                ids, dtype=torch.long, device=device
+            )
+            prompt_mask[i, -len(ids) :] = True
+
+        responses = torch.full((B, G, max_len), _PAD, dtype=torch.long, device=device)
+        response_mask = torch.zeros((B, G, max_len), dtype=torch.bool, device=device)
+        logprobs_old = torch.zeros((B, G, max_len), dtype=torch.float, device=device)
+
+        flat_idx = 0
+        response_texts: List[List[str]] = [[] for _ in range(B)]
+        for i in range(B):
+            for g in range(G):
+                token_ids, lps = results[flat_idx]
+                flat_idx += 1
+                n = len(token_ids)
+                if n:
+                    responses[i, g, :n] = torch.tensor(
+                        token_ids, dtype=torch.long, device=device
+                    )
+                    response_mask[i, g, :n] = True
+                    logprobs_old[i, g, :n] = torch.tensor(
+                        lps, dtype=torch.float, device=device
+                    )
+                response_texts[i].append(
+                    self.tokenizer.decode(token_ids, skip_special_tokens=True)
+                )
+
+        return RawRollout(
+            prompts=prompts_tensor,
+            prompt_mask=prompt_mask,
+            responses=responses,
+            response_mask=response_mask,
+            logprobs_old=logprobs_old,
+            prompt_texts=prompt_texts,
+            response_texts=response_texts,
+        )
+
+    def _prepare_prompts(self, batch: Dict) -> Tuple[List[str], List[List[int]]]:
+        """Render batch prompts to ``(texts, token_id_lists)``.
+
+        Returns two parallel lists of length B (number of prompts in
+        the batch).  Dispatches by batch keys:
+
+        - ``"messages"``: treated as a pre-built message list per sample.
+        - ``"instruction"`` (optionally ``"input"`` and ``"output"``): mapped
+          to ``system`` / ``user`` / ``assistant`` messages respectively.
+
+        Both paths go through the tokenizer's chat template with
+        ``add_generation_prompt=True``.
+        """
+        if "messages" in batch:
+            messages_list = batch["messages"]
+        elif "instruction" in batch:
+            instructions = batch["instruction"]
+            B = len(instructions)
+            inputs = batch.get("input") or [""] * B
+            outputs = batch.get("output") or [""] * B
+            messages_list = [
+                self._instruction_to_messages(i, u, o)
+                for i, u, o in zip(instructions, inputs, outputs)
+            ]
+        else:
+            raise ValueError(
+                "Rollout batch must contain either 'messages' or "
+                "'instruction' (optionally 'input'/'output'); got keys: "
+                f"{list(batch.keys())}"
+            )
+
+        try:
+            prompt_texts = self.tokenizer.apply_chat_template(
+                messages_list, tokenize=False, add_generation_prompt=True
+            )
+            if (
+                not isinstance(prompt_texts, list)
+                or len(prompt_texts) != len(messages_list)
+                or not all(isinstance(text, str) for text in prompt_texts)
+            ):
+                raise TypeError("Tokenizer does not support batched chat templates")
+            flat_prompt_ids = self.tokenizer.encode(prompt_texts)
+            if len(flat_prompt_ids) != len(messages_list) or not all(
+                isinstance(ids, list) for ids in flat_prompt_ids
+            ):
+                raise TypeError("Tokenizer does not support batched encoding")
+        except (TypeError, IndexError, KeyError):
+            # Keep compatibility with lightweight tokenizer adapters that only
+            # implement the single-conversation template API.
+            prompt_texts = []
+            flat_prompt_ids = []
+            for messages in messages_list:
+                text = self.tokenizer.apply_chat_template(
+                    messages, tokenize=False, add_generation_prompt=True
+                )
+                ids = self.tokenizer.apply_chat_template(
+                    messages, tokenize=True, add_generation_prompt=True
+                )
+                prompt_texts.append(text)
+                flat_prompt_ids.append(list(ids))
+        return prompt_texts, flat_prompt_ids
+
+    @staticmethod
+    def _instruction_to_messages(
+        instruction: str, inp: str = "", output: str = ""
+    ) -> List[Dict[str, str]]:
+        """Map instruction/input/output to chat messages.
+
+        Role mapping follows the convention used throughout the
+        preprocessing pipeline: ``instruction`` → system, ``input`` →
+        user, ``output`` → assistant.  Empty fields are skipped so a
+        bare instruction produces a ``[system]`` list and the chat
+        template's ``add_generation_prompt`` adds the assistant header
+        for sampling.
+        """
+        messages: List[Dict[str, str]] = []
+        if instruction:
+            messages.append({"role": "system", "content": instruction})
+        if inp:
+            messages.append({"role": "user", "content": inp})
+        if output:
+            messages.append({"role": "assistant", "content": output})
+        return messages
+
+
+class RolloutRunner:
+    """Produces :class:`RolloutResult` from a prompt batch.
+
+    Composes a :class:`RolloutGenerator` (generation + decoding) with a
+    :class:`BaseRewardModel` (scoring).  Maintains an internal cache so
+    the same batch prompt can be replayed for multiple gradient steps.
+    A new rollout is triggered every ``rollout_interval`` calls to
+    :meth:`step` (or after :meth:`clear_cache`).
+
+    The ``__call__`` contract returns a ``(RolloutResult, is_fresh)``
+    tuple — callers must use the boolean to detect a refreshed rollout
+    rather than relying on object identity.
+
+    Usage::
+
+        generator = RolloutGenerator(policy, tokenizer, pipeline, ...)
+        runner = RolloutRunner(generator, reward_model, rollout_interval=512)
+        result, is_fresh = runner(prompt_batch)
+        if is_fresh:
+            ...  # e.g. sync behaviour policy
+    """
+
+    def __init__(
+        self,
+        generator: RolloutGenerator,
+        reward_model: BaseRewardModel,
+        rollout_interval: int = 512,
+    ):
+        self.generator = generator
+        self.reward_model = reward_model
+        self.rollout_interval = rollout_interval
+
+        self._cache: Optional[RolloutResult] = None
+        self._cache_key = None
+        self._steps_since_rollout: int = 0
+
+    def step(self):
+        """Advance the internal counter (call once per optimizer step)."""
+        self._steps_since_rollout += 1
+
+    def clear_cache(self):
+        """Force next call to re-run rollout."""
+        self._cache = None
+        self._cache_key = None
+
+    @staticmethod
+    def _batch_key(batch: Dict):
+        """Build a stable key for the prompt fields accepted by the generator."""
+
+        def freeze(value):
+            if isinstance(value, dict):
+                return tuple(sorted((key, freeze(val)) for key, val in value.items()))
+            if isinstance(value, (list, tuple)):
+                return tuple(freeze(item) for item in value)
+            return value
+
+        fields = ("messages", "instruction", "input", "output")
+        return tuple(
+            (field, freeze(batch[field])) for field in fields if field in batch
+        )
+
+    def _score(self, raw: RawRollout) -> RolloutResult:
+        rewards = self.reward_model.score(raw.prompt_texts, raw.response_texts)
+        if not isinstance(rewards, Tensor):
+            rewards = torch.as_tensor(rewards, dtype=torch.float32)
+        expected_shape = raw.responses.shape[:2]
+        if rewards.shape != expected_shape:
+            raise ValueError(
+                f"Reward model returned shape {tuple(rewards.shape)}, "
+                f"expected {tuple(expected_shape)}"
+            )
+        if not torch.isfinite(rewards).all():
+            raise ValueError("Reward model returned non-finite values")
+        device = raw.prompts.device
+        return RolloutResult(
+            prompts=raw.prompts,
+            prompt_mask=raw.prompt_mask,
+            responses=raw.responses,
+            response_mask=raw.response_mask,
+            rewards=rewards.to(device=device),
+            logprobs_old=raw.logprobs_old,
+            prompt_texts=raw.prompt_texts,
+            response_texts=raw.response_texts,
+        )
+
+    def __call__(self, batch: Dict[str, Tensor]) -> Tuple[RolloutResult, bool]:
+        """Return ``(cached or fresh) RolloutResult`` plus an ``is_fresh`` flag.
+
+        Triggers a new rollout when ``_steps_since_rollout >= rollout_interval``
+        or when the cache is empty.
+        """
+        cache_key = self._batch_key(batch)
+        if (
+            self._cache is None
+            or cache_key != self._cache_key
+            or self._steps_since_rollout >= self.rollout_interval
+        ):
+            raw = self.generator.generate(batch)
+            self._cache = self._score(raw)
+            self._cache_key = cache_key
+            self._steps_since_rollout = 0
+            return self._cache, True
+        return self._cache, False

astrai/trainer/schedule.py

@@ -2,7 +2,7 @@
 
 import math
 from abc import ABC, abstractmethod
-from typing import Any, Dict, List
+from typing import List
 
 from torch.optim.lr_scheduler import LRScheduler
 
@@ -20,12 +20,6 @@ class BaseScheduler(LRScheduler, ABC):
         """Calculate the current learning rate."""
         raise NotImplementedError
 
-    def state_dict(self) -> Dict[str, Any]:
-        return super().state_dict()
-
-    def load_state_dict(self, state_dict: Dict[str, Any]):
-        super().load_state_dict(state_dict)
-
 
 class SchedulerFactory(BaseFactory["BaseScheduler"]):
     """Factory class for creating learning rate schedulers.

astrai/trainer/strategy.py

@@ -1,7 +1,7 @@
 """Training strategy implementations with factory pattern."""
 
-from abc import ABC, abstractmethod
-from typing import Callable, Dict, Union
+from abc import ABC
+from typing import Callable, Dict, List, Optional, TypedDict, Union
 
 import torch
 import torch.nn as nn
@@ -9,17 +9,20 @@ import torch.nn.functional as F
 from torch import Tensor
 
 from astrai.factory import BaseFactory
+from astrai.model.components.mlp import RouterStats
+from astrai.parallel.executor import broadcast_state_dict
+from astrai.trainer.rollout import RolloutResult
 
 
-def create_ref_model(
-    model_fn: Callable[[], nn.Module], state_dict: Dict[str, Tensor]
-) -> nn.Module:
-    """Create a frozen reference model from model_fn + full state dict."""
-    ref_model = model_fn()
-    ref_model.load_state_dict(state_dict)
-    ref_model.requires_grad_(False)
-    ref_model.eval()
-    return ref_model
+class LossOutput(TypedDict):
+    loss: Tensor
+    metrics: Dict[str, float]
+
+
+class LogprobsOutput(TypedDict):
+    logprobs: Tensor
+    aux_loss: Optional[Tensor]
+    router_stats: Optional[List[RouterStats]]
 
 
 def move_to_device(batch: Dict[str, Tensor], device: str) -> Dict[str, Tensor]:
@@ -28,17 +31,19 @@ def move_to_device(batch: Dict[str, Tensor], device: str) -> Dict[str, Tensor]:
 
 
 def get_logprobs(
-    model: Union[nn.Module, Callable[..., Dict[str, Tensor]]],
+    model: nn.Module,
     input_ids: Tensor,
-    mask: Tensor,
+    attn_mask: Tensor,
+    loss_mask: Tensor,
     reduction: str,
-) -> Tensor:
+) -> LogprobsOutput:
     """Compute token-wise log probabilities from model outputs.
 
     Args:
         model: The language model
         input_ids: Input token IDs of shape [batch_size, seq_len]
-        mask: Attention mask of shape [batch_size, seq_len]
+        attn_mask: Attention mask passed to the model (may include causal).
+        loss_mask: Per-token mask for loss reduction.
         reduction: How to reduce over sequence dimension ("mean", "sum", "none")
 
     Returns:
@@ -51,9 +56,13 @@ def get_logprobs(
         )
 
     shifted_input_ids = input_ids[:, 1:]
-    shifted_mask = mask[:, 1:]
+    shifted_loss_mask = loss_mask[:, 1:]
 
-    logits = model(input_ids[:, :-1], mask[:, :-1])["logits"]
+    outputs = model(
+        input_ids[:, :-1],
+        attn_mask[:, :, :-1, :-1] if attn_mask.dim() == 4 else attn_mask[:, :-1],
+    )
+    logits = outputs["logits"]
     log_probs = torch.log_softmax(logits.float(), dim=-1)
 
     token_logprobs = torch.gather(
@@ -61,13 +70,18 @@ def get_logprobs(
     ).squeeze(-1)
 
     if reduction == "mean":
-        return (token_logprobs * shifted_mask).sum(dim=-1) / shifted_mask.sum(
+        logprobs = (token_logprobs * shifted_loss_mask).sum(
             dim=-1
-        ).clamp(min=1.0)
+        ) / shifted_loss_mask.sum(dim=-1).clamp(min=1.0)
     elif reduction == "sum":
-        return (token_logprobs * shifted_mask).sum(dim=-1)
+        logprobs = (token_logprobs * shifted_loss_mask).sum(dim=-1)
     else:
-        return token_logprobs * shifted_mask
+        logprobs = token_logprobs * shifted_loss_mask
+    return {
+        "logprobs": logprobs,
+        "aux_loss": outputs.get("aux_loss"),
+        "router_stats": outputs.get("router_stats"),
+    }
 
 
 def make_doc_boundary_mask(position_ids: Tensor) -> Tensor:
@@ -86,8 +100,78 @@ def make_doc_boundary_mask(position_ids: Tensor) -> Tensor:
     return (same_doc & causal).unsqueeze(1)
 
 
+def _collect_moe_diagnostics(
+    router_stats_list: List[RouterStats],
+) -> Dict[str, float]:
+    """Collect MoE routing diagnostic metrics from per-layer router stats.
+
+    Args:
+        router_stats_list: One :class:`RouterStats` dict per MoE layer with
+            keys ``probs`` (N, E) and ``topk_indices`` (N, K), both detached.
+
+    Returns:
+        Dict with keys: router_entropy, dead_expert_fraction,
+        load_imbalance_mean, load_imbalance_max.  Values are averaged
+        across layers.
+    """
+    layer_entropies: List[Tensor] = []
+    layer_dead_fractions: List[Tensor] = []
+    layer_imbalance_means: List[Tensor] = []
+    layer_imbalance_maxs: List[Tensor] = []
+
+    for stats in router_stats_list:
+        probs = stats["probs"].float()
+        topk_indices = stats["topk_indices"]
+        num_experts = probs.shape[-1]
+        if num_experts == 0:
+            continue
+        probs = probs.reshape(-1, num_experts)
+        if probs.numel() == 0:
+            continue
+
+        # Router entropy
+        entropy = -(probs * torch.log(probs.clamp_min(1e-8))).sum(dim=-1).mean()
+
+        # Load from the actual dispatch: one-hot sum of top-k assignments.
+        expert_counts = F.one_hot(topk_indices, num_experts).sum(dim=(0, 1)).float()
+        ideal_load = expert_counts.mean()  # N*K / E
+        load_ratios = expert_counts / max(float(ideal_load), 1.0)
+        imbalance_mean = (load_ratios - 1.0).abs().mean()
+        imbalance_max = load_ratios.max()
+        dead_fraction = (expert_counts == 0).float().mean()
+
+        layer_entropies.append(entropy)
+        layer_dead_fractions.append(dead_fraction)
+        layer_imbalance_means.append(imbalance_mean)
+        layer_imbalance_maxs.append(imbalance_max)
+
+    if not layer_entropies:
+        return {}
+
+    return {
+        "router_entropy": float(torch.stack(layer_entropies).mean().cpu().item()),
+        "dead_expert_fraction": float(
+            torch.stack(layer_dead_fractions).mean().cpu().item()
+        ),
+        "load_imbalance_mean": float(
+            torch.stack(layer_imbalance_means).mean().cpu().item()
+        ),
+        "load_imbalance_max": float(
+            torch.stack(layer_imbalance_maxs).mean().cpu().item()
+        ),
+    }
+
+
 class BaseStrategy(ABC):
-    """Abstract base class for training strategies."""
+    """Abstract base class for training strategies.
+
+    When a :class:`~astrai.trainer.rollout.RolloutRunner` is injected via
+    :meth:`set_rollout_runner`, the strategy transparently switches to
+    online mode: each ``__call__`` produces a :class:`RolloutResult`,
+    converts it to a training batch via :meth:`prepare_from_rollout`, and
+    then computes the loss.  Without a runner the strategy runs in
+    offline mode and consumes the batch directly.
+    """
 
     def __init__(
         self,
@@ -98,10 +182,11 @@ class BaseStrategy(ABC):
         self.model = model
         self.device = device
         self.executor = kwargs.pop("executor", None)
-        self.model_fn = kwargs.pop("model_fn", None)
-        self.extra_kwargs = kwargs
+        self.moe_aux_loss_coef = kwargs.pop("moe_aux_loss_coef", 0.01)
+        self._moe_metrics: Dict[str, float] = {}
+        self.strategy_kwargs = kwargs
+        self._rollout_runner = None
 
-    @abstractmethod
     def compute_loss(self, batch: Dict[str, Tensor]) -> Tensor:
         """Compute loss for the given batch.
 
@@ -111,11 +196,98 @@ class BaseStrategy(ABC):
         Returns:
             Computed loss tensor
         """
-        raise NotImplementedError
+        return self.compute_loss_output(batch)["loss"]
 
-    def __call__(self, batch: Dict[str, Tensor]) -> Tensor:
-        """Allow calling strategy directly as a callable."""
-        return self.compute_loss(batch)
+    def compute_loss_output(self, batch: Dict[str, Tensor]) -> LossOutput:
+        return self._normalize_output(self.compute_loss(batch))
+
+    def _loss_output(
+        self,
+        task_loss: Tensor,
+        metrics: Dict[str, Tensor],
+        aux_loss: Optional[Tensor] = None,
+        router_stats: Optional[List[RouterStats]] = None,
+    ) -> LossOutput:
+        total_loss = task_loss
+        if aux_loss is not None:
+            weighted_aux_loss = self.moe_aux_loss_coef * aux_loss
+            total_loss = total_loss + weighted_aux_loss
+            metrics["moe_aux_loss"] = aux_loss
+            metrics["moe_aux_loss_weighted"] = weighted_aux_loss
+            self._refresh_moe_diagnostics(aux_loss, router_stats)
+        metrics["loss"] = total_loss
+        return {
+            "loss": total_loss,
+            "metrics": {name: value.detach().item() for name, value in metrics.items()},
+        }
+
+    @staticmethod
+    def _normalize_output(output: Union[LossOutput, Tensor]) -> LossOutput:
+        if isinstance(output, dict):
+            return output
+        return {"loss": output, "metrics": {"loss": output.detach().item()}}
+
+    def supports_online(self) -> bool:
+        """Whether this strategy can operate with a rollout runner.
+
+        Base implementation returns ``False``; strategies that implement
+        :meth:`prepare_from_rollout` should override to return ``True``.
+        """
+        return False
+
+    def set_rollout_runner(self, runner):
+        """Inject a :class:`RolloutRunner` to enable online rollout mode."""
+        self._rollout_runner = runner
+
+    def prepare_from_rollout(self, result: RolloutResult) -> Dict[str, Tensor]:
+        """Map a :class:`RolloutResult` to the batch layout expected by
+        :meth:`compute_loss`.
+
+        Strategies that return ``True`` from :meth:`supports_online` must
+        override this.  Default raises :class:`NotImplementedError`.
+        """
+        raise NotImplementedError(
+            f"{type(self).__name__} does not support online rollout"
+        )
+
+    def _on_rollout_refresh(self):
+        """Hook fired when a fresh rollout result is produced.
+
+        Override to refresh stale state (e.g. syncing the behaviour
+        policy).  Default is a no-op.
+        """
+        pass
+
+    def _refresh_moe_diagnostics(
+        self,
+        aux_loss: Tensor,
+        router_stats: Optional[List[RouterStats]] = None,
+    ) -> None:
+        """Collect MoE routing diagnostics from the latest forward pass.
+
+        Populates ``self._moe_metrics`` with router entropy, dead expert
+        fraction, load imbalance, and aux_loss.  Called from
+        :meth:`_loss_output` when an MoE aux loss is present.
+        """
+        self._moe_metrics = _collect_moe_diagnostics(router_stats or [])
+        self._moe_metrics["aux_loss"] = float(aux_loss.detach().cpu().item())
+
+    def on_optimizer_step(self):
+        """Advance online rollout state after a successful optimizer step."""
+        if self._rollout_runner is not None:
+            self._rollout_runner.step()
+
+    def __call__(self, batch: Dict[str, Tensor]) -> LossOutput:
+        """Run offline or online forward depending on runner injection."""
+        if self._rollout_runner is None:
+            return self.compute_loss_output(batch)
+
+        result, is_fresh = self._rollout_runner(batch)
+        if is_fresh:
+            self._on_rollout_refresh()
+
+        train_batch = self.prepare_from_rollout(result)
+        return self.compute_loss_output(train_batch)
 
 
 class StrategyFactory(BaseFactory["BaseStrategy"]):
@@ -142,6 +314,7 @@ class SEQStrategy(BaseStrategy):
     """Standard next-token prediction training strategy.
 
     Computes cross-entropy loss for next token prediction.
+    Optionally adds MoE load balancing auxiliary loss.
     """
 
     def __init__(
@@ -154,10 +327,11 @@ class SEQStrategy(BaseStrategy):
         super().__init__(model, device, **kwargs)
         self.label_smoothing = label_smoothing
 
-    def compute_loss(self, batch: Dict[str, Tensor]) -> Tensor:
+    def compute_loss_output(self, batch: Dict[str, Tensor]) -> LossOutput:
         batch = move_to_device(batch, self.device)
         input_ids, target_ids = batch["input_ids"], batch["target_ids"]
-        logits = self.model(input_ids=input_ids)["logits"]
+        outputs = self.model(input_ids=input_ids)
+        logits = outputs["logits"]
 
         loss = F.cross_entropy(
             input=logits.flatten(0, 1).float(),
@@ -165,7 +339,12 @@ class SEQStrategy(BaseStrategy):
             label_smoothing=self.label_smoothing,
         )
 
-        return loss
+        return self._loss_output(
+            loss,
+            {"task_loss": loss},
+            outputs.get("aux_loss"),
+            outputs.get("router_stats"),
+        )
 
 
 @StrategyFactory.register("sft")
@@ -173,6 +352,7 @@ class SFTStrategy(BaseStrategy):
     """Supervised Fine-tuning strategy with loss masking.
 
     Applies cross-entropy loss only to tokens where loss_mask is True.
+    Optionally adds MoE load balancing auxiliary loss.
     """
 
     def __init__(
@@ -185,7 +365,7 @@ class SFTStrategy(BaseStrategy):
         super().__init__(model, device, **kwargs)
         self.label_smoothing = label_smoothing
 
-    def compute_loss(self, batch: Dict[str, Tensor]) -> Tensor:
+    def compute_loss_output(self, batch: Dict[str, Tensor]) -> LossOutput:
         batch = move_to_device(batch, self.device)
         input_ids, target_ids, position_ids, loss_mask = (
             batch["input_ids"],
@@ -197,9 +377,10 @@ class SFTStrategy(BaseStrategy):
         ignore_index = -100
         input_mask = make_doc_boundary_mask(position_ids)
         target_ids = target_ids.masked_fill(~loss_mask, ignore_index)
-        logits = self.model(
+        outputs = self.model(
             input_ids=input_ids, position_ids=position_ids, input_mask=input_mask
-        )["logits"]
+        )
+        logits = outputs["logits"]
 
         loss = F.cross_entropy(
             input=logits.flatten(0, 1).float(),
@@ -208,7 +389,12 @@ class SFTStrategy(BaseStrategy):
             label_smoothing=self.label_smoothing,
         )
 
-        return loss
+        return self._loss_output(
+            loss,
+            {"task_loss": loss},
+            outputs.get("aux_loss"),
+            outputs.get("router_stats"),
+        )
 
 
 @StrategyFactory.register("dpo")
@@ -225,7 +411,7 @@ class DPOStrategy(BaseStrategy):
         device: str,
         ref_model: nn.Module,
         beta: float = 0.1,
-        reduction: str = "mean",
+        reduction: str = "sum",
         **kwargs,
     ):
         super().__init__(model, device, **kwargs)
@@ -233,20 +419,41 @@ class DPOStrategy(BaseStrategy):
         self.beta = beta
         self.reduction = reduction
 
-    def compute_loss(self, batch: Dict[str, Tensor]) -> Tensor:
+    def compute_loss_output(self, batch: Dict[str, Tensor]) -> LossOutput:
         batch = move_to_device(batch, self.device)
         chosen_ids, rejected_ids = batch["chosen"], batch["rejected"]
         chosen_mask, rejected_mask = batch["chosen_mask"], batch["rejected_mask"]
 
         concat_ids = torch.cat([chosen_ids, rejected_ids], dim=0)
-        concat_mask = torch.cat([chosen_mask, rejected_mask], dim=0)
+        concat_loss_mask = torch.cat([chosen_mask, rejected_mask], dim=0)
 
-        log_pi = get_logprobs(self.model, concat_ids, concat_mask, self.reduction)
+        # Build full attention mask: key-padding + causal
+        key_pad = concat_ids.bool()[:, None, None, :]  # [B*2, 1, 1, S]
+        S = key_pad.shape[-1]
+        causal = torch.tril(
+            torch.ones(S, S, dtype=torch.bool, device=concat_ids.device)
+        )[None, None, :, :]  # [1, 1, S, S]
+        full_mask = key_pad & causal  # [B*2, 1, S, S] — composed
+
+        policy_output = get_logprobs(
+            self.model,
+            concat_ids,
+            full_mask,
+            concat_loss_mask,
+            self.reduction,
+        )
+        log_pi = policy_output["logprobs"]
+        aux_loss = policy_output["aux_loss"]
 
         with torch.no_grad():
-            log_ref = get_logprobs(
-                self.ref_model, concat_ids, concat_mask, self.reduction
+            ref_output = get_logprobs(
+                self.ref_model,
+                concat_ids,
+                full_mask,
+                concat_loss_mask,
+                self.reduction,
             )
+            log_ref = ref_output["logprobs"]
 
         log_pi_chosen = log_pi[: chosen_ids.shape[0]]
         log_pi_rejected = log_pi[chosen_ids.shape[0] :]
@@ -259,7 +466,35 @@ class DPOStrategy(BaseStrategy):
         ratio_diff = pi_log_ratio - ref_log_ratio
         dpo_loss = -F.logsigmoid(self.beta * ratio_diff).mean()
 
-        return dpo_loss
+        return self._loss_output(
+            dpo_loss,
+            {"dpo_loss": dpo_loss},
+            aux_loss,
+            policy_output.get("router_stats"),
+        )
+
+    def supports_online(self) -> bool:
+        return True
+
+    def prepare_from_rollout(self, result: RolloutResult) -> Dict[str, Tensor]:
+        """Pick best/worst response per prompt by reward as chosen/rejected."""
+        rewards = result.rewards
+        responses = result.responses
+        masks = result.response_mask
+        best = rewards.argmax(dim=-1)
+        worst = rewards.argmin(dim=-1)
+        B = responses.shape[0]
+        idx = torch.arange(B, device=responses.device)
+        chosen = responses[idx, best]
+        chosen_mask = masks[idx, best].float()
+        rejected = responses[idx, worst]
+        rejected_mask = masks[idx, worst].float()
+        return {
+            "chosen": chosen,
+            "chosen_mask": chosen_mask,
+            "rejected": rejected,
+            "rejected_mask": rejected_mask,
+        }
 
 
 @StrategyFactory.register("grpo")
@@ -302,9 +537,13 @@ class GRPOStrategy(BaseStrategy):
 
     def sync_old_model(self):
         """Copy current policy weights to old model."""
-        self.old_model.load_state_dict(self.executor.unwrap_model(self.model))
+        state_dict = self.executor.unwrap_model(self.model)
+        if self.executor.use_distributed:
+            state_dict = broadcast_state_dict(state_dict)
+        if state_dict is not None:
+            self.old_model.load_state_dict(state_dict)
 
-    def compute_loss(self, batch: Dict[str, Tensor]) -> Tensor:
+    def compute_loss_output(self, batch: Dict[str, Tensor]) -> LossOutput:
         batch = move_to_device(batch, self.device)
         prompts = batch["prompts"]
         responses = batch["responses"]
@@ -315,6 +554,12 @@ class GRPOStrategy(BaseStrategy):
         responses_flat = responses.view(-1, response_len)
         masks_flat = masks.view(-1, response_len)
         prompt_expanded = prompts.unsqueeze(1).repeat(1, group_size, 1).flatten(0, 1)
+        prompt_mask = batch.get("prompt_mask")
+        if prompt_mask is None:
+            prompt_mask = prompts.ne(0)
+        prompt_mask_expanded = (
+            prompt_mask.unsqueeze(1).expand(-1, group_size, -1).flatten(0, 1)
+        )
         prompt_len = prompt_expanded.size(1)
 
         full_sequences = torch.cat([prompt_expanded, responses_flat], dim=-1)
@@ -322,21 +567,40 @@ class GRPOStrategy(BaseStrategy):
         # response tokens.  get_logprobs shifts the mask by one position, so
         # the first response token's logprob (predicted from the last prompt
         # token) is correctly included.
-        full_masks = torch.cat([torch.zeros_like(prompt_expanded), masks_flat], dim=-1)
+        full_masks = torch.cat(
+            [torch.zeros_like(prompt_expanded, dtype=torch.bool), masks_flat], dim=-1
+        )
+
+        # Build full attention mask: key-padding + causal
+        key_pad = torch.cat([prompt_mask_expanded, masks_flat.bool()], dim=-1)[
+            :, None, None, :
+        ]
+        S = key_pad.shape[-1]
+        causal = torch.tril(
+            torch.ones(S, S, dtype=torch.bool, device=full_sequences.device)
+        )[None, None, :, :]
+        attn_mask = key_pad & causal
 
         # get_logprobs returns [B*G, S-1] (S = prompt_len + response_len).
         # Response token logprobs occupy the last ``response_len`` positions
         # (the first response token is predicted from the last prompt token).
-        token_log_probs_policy = get_logprobs(
-            self.model, full_sequences, full_masks, "none"
-        )[:, prompt_len - 1 :]
+        policy_output = get_logprobs(
+            self.model, full_sequences, attn_mask, full_masks, "none"
+        )
+        token_log_probs_policy = policy_output["logprobs"]
+        aux_loss = policy_output["aux_loss"]
+        token_log_probs_policy = token_log_probs_policy[:, prompt_len - 1 :]
         with torch.no_grad():
-            token_log_probs_old = get_logprobs(
-                self.old_model, full_sequences, full_masks, "none"
-            )[:, prompt_len - 1 :]
-            token_log_probs_ref = get_logprobs(
-                self.ref_model, full_sequences, full_masks, "none"
-            )[:, prompt_len - 1 :]
+            old_output = get_logprobs(
+                self.old_model, full_sequences, attn_mask, full_masks, "none"
+            )
+            token_log_probs_old = old_output["logprobs"]
+            token_log_probs_old = token_log_probs_old[:, prompt_len - 1 :]
+            ref_output = get_logprobs(
+                self.ref_model, full_sequences, attn_mask, full_masks, "none"
+            )
+            token_log_probs_ref = ref_output["logprobs"]
+            token_log_probs_ref = token_log_probs_ref[:, prompt_len - 1 :]
 
         # Reshape to [B, G, response_len]
         token_log_probs_policy = token_log_probs_policy.view(batch_size, group_size, -1)
@@ -369,6 +633,33 @@ class GRPOStrategy(BaseStrategy):
         kl_per_token = r - torch.log(r + eps) - 1.0
         kl_penalty = self.kl_coef * (kl_per_token * token_masks).sum() / token_count
 
-        total_loss = policy_loss + kl_penalty
+        task_loss = policy_loss + kl_penalty
+        return self._loss_output(
+            task_loss,
+            {"policy_loss": policy_loss, "kl_loss": kl_penalty},
+            aux_loss,
+            policy_output.get("router_stats"),
+        )
 
-        return total_loss
+    def supports_online(self) -> bool:
+        return True
+
+    def prepare_from_rollout(self, result: RolloutResult) -> Dict[str, Tensor]:
+        return {
+            "prompts": result.prompts,
+            "prompt_mask": result.prompt_mask,
+            "responses": result.responses,
+            "masks": result.response_mask,
+            "rewards": result.rewards,
+        }
+
+    def _on_rollout_refresh(self):
+        """Sync the behaviour policy whenever a fresh rollout arrives."""
+        self.sync_old_model()
+
+
+# Factory aliases: online variants use the same strategy class; the
+# ``RolloutRunner`` is injected by ``TrainContextBuilder`` to enable
+# online mode, so no separate subclass is needed.
+StrategyFactory.register("online_grpo")(GRPOStrategy)
+StrategyFactory.register("online_dpo")(DPOStrategy)

astrai/trainer/train_callback.py

@@ -3,6 +3,7 @@ import logging
 import os
 import sys
 import time
+from functools import partial
 from pathlib import Path
 from typing import IO, Callable, List, Optional, Protocol, runtime_checkable
 
@@ -18,8 +19,10 @@ from astrai.parallel.setup import get_current_device
 from astrai.serialization import Checkpoint
 from astrai.trainer.metric_util import (
     ctx_get_grad_norm,
+    ctx_get_grad_snr,
     ctx_get_loss,
     ctx_get_lr,
+    ctx_get_moe_metric,
     ctx_get_val_loss,
 )
 from astrai.trainer.train_context import TrainContext
@@ -113,6 +116,8 @@ class GradientCheckpointingCallback(TrainCallback):
             del module._original_forward
 
     def on_train_begin(self, context: TrainContext):
+        if not self.modules:
+            return
         context.model.apply(self._enable)
         logger.info("Gradient checkpointing enabled")
 
@@ -235,7 +240,7 @@ class ProgressBarCallback(TrainCallback):
 class MetricCallback(TrainCallback):
     def __init__(
         self,
-        log_dir: str,
+        ckpt_dir: str,
         save_interval: int,
         metrics: List[str] = None,
         val_step: int = 0,
@@ -246,8 +251,7 @@ class MetricCallback(TrainCallback):
         self.val_step = val_step
         self._next_val_step = 0
 
-        self.log_dir = Path(log_dir) if log_dir else Path.cwd() / "logs"
-        self.log_dir.mkdir(parents=True, exist_ok=True)
+        self.ckpt_dir = Path(ckpt_dir) if ckpt_dir else Path.cwd() / "checkpoint"
 
         self.log_cache = []
 
@@ -256,14 +260,41 @@ class MetricCallback(TrainCallback):
             "lr": ctx_get_lr,
             "val_loss": ctx_get_val_loss,
             "grad_norm": ctx_get_grad_norm,
+            "grad_snr": ctx_get_grad_snr,
+            "moe_aux_loss": partial(ctx_get_moe_metric, key="aux_loss"),
+            "router_entropy": partial(ctx_get_moe_metric, key="router_entropy"),
+            "dead_expert_fraction": partial(
+                ctx_get_moe_metric, key="dead_expert_fraction"
+            ),
+            "load_imbalance_mean": partial(
+                ctx_get_moe_metric, key="load_imbalance_mean"
+            ),
+            "load_imbalance_max": partial(ctx_get_moe_metric, key="load_imbalance_max"),
         }
 
     def _metrics(self, context: TrainContext, names):
-        return {
-            m: self._metric_funcs[m](context)
-            for m in names
-            if self._metric_funcs[m](context) is not None
-        }
+        metrics = dict(context.metrics)
+        for name in names:
+            metric_fn = self._metric_funcs.get(name)
+            if metric_fn is None:
+                continue
+            value = metric_fn(context)
+            if value is not None:
+                metrics[name] = value
+        selected = set(context.metrics) | set(names)
+        selected.discard("*")
+        result = {name: metrics[name] for name in selected if name in metrics}
+        if context.world_size > 1 and dist.is_initialized() and result:
+            metric_names = sorted(result)
+            values = torch.tensor(
+                [result[name] for name in metric_names],
+                dtype=torch.float32,
+                device=get_current_device(),
+            )
+            dist.all_reduce(values, op=dist.ReduceOp.SUM)
+            values /= context.world_size
+            result.update(zip(metric_names, values.tolist()))
+        return result
 
     @only_on_rank(0)
     def _append(self, event_type: str, context: TrainContext, **extra):
@@ -285,8 +316,8 @@ class MetricCallback(TrainCallback):
 
         with torch.no_grad():
             for batch in context.val_dataloader:
-                loss = context.strategy(batch)
-                total_loss += loss.item()
+                loss_output = context.strategy(batch)
+                total_loss += loss_output["loss"].item()
                 num_batches += 1
 
         if context.world_size > 1 and dist.is_initialized():
@@ -306,13 +337,15 @@ class MetricCallback(TrainCallback):
 
     @only_on_rank(0)
     def _flush(self, epoch, step):
-        log_file = self.log_dir / f"epoch_{epoch}_step_{step}_metric.jsonl"
+        log_file = self.ckpt_dir / f"epoch_{epoch}_step_{step}" / "metric.jsonl"
         log_file.parent.mkdir(parents=True, exist_ok=True)
         with open(log_file, "w") as f:
             for log in self.log_cache:
                 f.write(json.dumps(log) + "\n")
 
     def on_optimizer_step(self, context):
+        context.grad_snr_tracker.update(context.model)
+
         if (
             context.val_dataloader is not None
             and self.val_step > 0

astrai/trainer/train_context.py

@@ -1,3 +1,5 @@
+import logging
+import threading
 from dataclasses import dataclass, field
 from pathlib import Path
 from typing import Any, Dict, Optional, Self
@@ -6,14 +8,27 @@ import torch
 import torch.nn as nn
 from torch.utils.data import DataLoader, random_split
 
+from astrai.config.model_config import ConfigFactory
 from astrai.config.train_config import TrainConfig
-from astrai.dataset import ResumableDistributedSampler
+from astrai.dataset import RDSampler
+from astrai.inference.scheduler import InferenceScheduler
 from astrai.model.components.lora import inject_lora
-from astrai.parallel.executor import BaseExecutor, ExecutorFactory
+from astrai.parallel.executor import BaseExecutor, ExecutorFactory, create_ref_model
 from astrai.parallel.setup import get_current_device, get_rank, get_world_size
 from astrai.protocols import OptimizerProtocol, SchedulerProtocol
-from astrai.serialization import Checkpoint, load_json
-from astrai.trainer.strategy import BaseStrategy, StrategyFactory, create_ref_model
+from astrai.serialization import (
+    Checkpoint,
+    adapt_config,
+    convert_hf_weights,
+    load_json,
+    looks_like_hf_state_dict,
+)
+from astrai.tokenize import AutoTokenizer
+from astrai.trainer.metric_util import GradSNRTracker
+from astrai.trainer.rollout import RolloutGenerator, RolloutRunner
+from astrai.trainer.strategy import BaseStrategy, StrategyFactory
+
+logger = logging.getLogger(__name__)
 
 
 @dataclass
@@ -27,11 +42,12 @@ class TrainContext:
     config: TrainConfig = field(default=None)
     model_config: dict = field(default_factory=dict)
     executor: BaseExecutor = field(default=None)
-
     epoch: int = field(default=0)
     consumed_samples: int = field(default=0)
     loss: float = field(default=0.0)
+    metrics: Dict[str, float] = field(default_factory=dict)
     grad_norm: Optional[float] = field(default=None)
+    grad_snr_tracker: GradSNRTracker = field(default_factory=GradSNRTracker)
     val_dataloader: Optional[DataLoader] = field(default=None)
     val_loss: Optional[float] = field(default=None)
 
@@ -39,6 +55,15 @@ class TrainContext:
     rank: int = field(default=0)
     kwargs: Dict[str, Any] = field(default_factory=dict)
 
+    _stop_event: threading.Event = field(default_factory=threading.Event)
+
+    @property
+    def stop_requested(self) -> bool:
+        return self._stop_event.is_set()
+
+    def request_stop(self) -> None:
+        self._stop_event.set()
+
     @property
     def optimizer_step(self) -> int:
         return self.consumed_samples // (
@@ -48,6 +73,15 @@ class TrainContext:
         )
 
 
+@dataclass
+class _PreloadedState:
+    model_config: dict = field(default_factory=dict)
+    state_dict: Optional[dict] = None
+    epoch: int = 0
+    consumed_samples: int = 0
+    checkpoint: Optional[Checkpoint] = None
+
+
 class TrainContextBuilder:
     def __init__(
         self,
@@ -63,154 +97,241 @@ class TrainContextBuilder:
         return self
 
     def build(self) -> TrainContext:
-        cfg = self.config
-        device = get_current_device()
+        # Resolve persisted state.
+        preloaded_state = self._load_preloaded_state()
 
-        executor = ExecutorFactory.create(
+        # Build the core training components and restore their persisted state.
+        executor = self._create_executor()
+        context = self._create_context(preloaded_state, executor)
+        self._prepare_model(context, executor, preloaded_state)
+        self._restore_optimizer_state(context)
+
+        # Resolve datasets.
+        train_dataset, val_dataset = self._get_datasets()
+        self._create_dataloaders(context, train_dataset, val_dataset)
+
+        # Strategies depend on the prepared model; online rollout depends on both.
+        strategy_kwargs = self._create_strategy(context, executor)
+        self._configure_rollout(context, strategy_kwargs)
+
+        return context
+
+    def _create_executor(self) -> BaseExecutor:
+        cfg = self.config
+        return ExecutorFactory.create(
             cfg.parallel_mode,
             grad_accum_steps=cfg.grad_accum_steps,
             **cfg.executor_kwargs,
         )
 
-        model = cfg.model_fn()
-        model = model.to(device=device)
-
-        model_config = {}
+    def _load_preloaded_state(self) -> _PreloadedState:
+        cfg = self.config
+        state = _PreloadedState(
+            epoch=cfg.start_epoch,
+            consumed_samples=cfg.start_samples * get_world_size(),
+        )
         if self._param_path:
             config_path = Path(self._param_path) / "config.json"
             if config_path.exists():
-                model_config = load_json(config_path)
-
-        if not model_config and hasattr(model, "config"):
-            model_config = model.config.to_dict()
-
-        context = TrainContext(
-            model=model,
-            world_size=get_world_size(),
-            rank=get_rank(),
-            config=cfg,
-            model_config=model_config,
-            executor=executor,
-        )
-
-        if self._param_path:
+                state.model_config = adapt_config(load_json(config_path))
             checkpoint = Checkpoint.load_any(self._param_path)
             if checkpoint is not None:
-                model.load_state_dict(checkpoint.state_dict, strict=False)
                 if checkpoint.config:
-                    context.model_config = checkpoint.config
-
+                    checkpoint.config = adapt_config(checkpoint.config)
+                if checkpoint.state_dict and looks_like_hf_state_dict(
+                    checkpoint.state_dict
+                ):
+                    checkpoint.state_dict = convert_hf_weights(
+                        checkpoint.state_dict,
+                        ConfigFactory.load(checkpoint.config or state.model_config),
+                    )
+                state.state_dict = checkpoint.state_dict
+                state.model_config = checkpoint.config or state.model_config
                 if self._resume:
-                    context.epoch = checkpoint.epoch or cfg.start_epoch
-                    if checkpoint.consumed_samples > 0:
-                        per_step = (
-                            cfg.batch_per_device
-                            * context.world_size
-                            * cfg.grad_accum_steps
-                        )
-                        context.consumed_samples = (
-                            checkpoint.consumed_samples // per_step
-                        ) * per_step
-                    else:
-                        context.consumed_samples = (
-                            cfg.start_samples * context.world_size
-                        )
-                    context.checkpoint = checkpoint
+                    state.epoch = checkpoint.epoch
+                    per_step = (
+                        cfg.batch_per_device * get_world_size() * cfg.grad_accum_steps
+                    )
+                    state.consumed_samples = (
+                        checkpoint.consumed_samples // per_step * per_step
+                    )
+                    state.checkpoint = checkpoint
+        if not state.model_config:
+            model = cfg.model_fn()
+            if hasattr(model, "config"):
+                state.model_config = model.config.to_dict()
+        return state
 
-        if cfg.lora is not None:
-            inject_lora(
-                model,
-                r=cfg.lora.r,
-                alpha=cfg.lora.alpha,
-                target_modules=set(cfg.lora.target_modules),
-            )
-
-        context.optimizer = cfg.optimizer_fn(model)
-        context.scheduler = cfg.scheduler_fn(context.optimizer)
-
-        train_dataset = cfg.dataset
-        val_dataset = cfg.val_dataset
-
-        if val_dataset is None and cfg.val_split is not None:
-            n_total = len(cfg.dataset)
-            n_val = max(1, int(n_total * cfg.val_split))
-            n_train = n_total - n_val
-            generator = torch.Generator().manual_seed(cfg.random_seed)
-            train_dataset, val_dataset = random_split(
-                cfg.dataset, [n_train, n_val], generator=generator
-            )
-
-        sampler_offset = context.consumed_samples // context.world_size
-        sampler = ResumableDistributedSampler(
-            data_source=train_dataset,
-            start_epoch=context.epoch,
-            start_iter=sampler_offset,
-            seed=cfg.random_seed,
+    def _create_context(
+        self, state: _PreloadedState, executor: BaseExecutor
+    ) -> TrainContext:
+        return TrainContext(
+            world_size=get_world_size(),
+            rank=get_rank(),
+            config=self.config,
+            model_config=state.model_config,
+            executor=executor,
+            epoch=state.epoch,
+            consumed_samples=state.consumed_samples,
+            checkpoint=state.checkpoint,
         )
-        context.dataloader = DataLoader(
-            train_dataset,
+
+    def _prepare_model(
+        self, context: TrainContext, executor: BaseExecutor, state: _PreloadedState
+    ) -> None:
+        cfg = self.config
+        device = get_current_device()
+
+        def before_wrap(model):
+            model = model.to(device=device)
+            if cfg.lora is not None:
+                inject_lora(
+                    model,
+                    r=cfg.lora.r,
+                    alpha=cfg.lora.alpha,
+                    target_modules=set(cfg.lora.target_modules),
+                )
+            if state.state_dict is not None:
+                model.load_state_dict(state.state_dict, strict=False)
+            return model
+
+        def after_wrap(model):
+            if cfg.compile_mode is not None:
+                logger.info("torch.compile enabled (mode=%s)", cfg.compile_mode)
+                model = torch.compile(model, mode=cfg.compile_mode)
+            return model
+
+        context.model, context.optimizer, context.scheduler = executor.prepare(
+            cfg.model_fn,
+            cfg.optimizer_fn,
+            cfg.scheduler_fn,
+            before_wrap=before_wrap,
+            after_wrap=after_wrap,
+        )
+
+    def _get_datasets(self):
+        cfg = self.config
+        if cfg.val_dataset is not None or cfg.val_split is None:
+            return cfg.dataset, cfg.val_dataset
+        n_val = max(1, int(len(cfg.dataset) * cfg.val_split))
+        generator = torch.Generator().manual_seed(cfg.random_seed)
+        return random_split(
+            cfg.dataset, [len(cfg.dataset) - n_val, n_val], generator=generator
+        )
+
+    def _create_dataloaders(
+        self, context: TrainContext, train_dataset, val_dataset
+    ) -> None:
+        sampler_offset = context.consumed_samples // context.world_size
+        if self._resume and sampler_offset > 0:
+            samples_per_replica = (
+                len(train_dataset) + context.world_size - 1
+            ) // context.world_size
+            if samples_per_replica > 0:
+                context.epoch = sampler_offset // samples_per_replica
+        context.dataloader = self._create_dataloader(
+            train_dataset, context.epoch, sampler_offset
+        )
+        if val_dataset is not None:
+            context.val_dataloader = self._create_dataloader(
+                val_dataset, 0, 0, shuffle=False
+            )
+
+    def _create_dataloader(
+        self, dataset, epoch: int, start_iter: int, shuffle: bool = True
+    ):
+        cfg = self.config
+        sampler = RDSampler(
+            dataset,
+            start_epoch=epoch,
+            start_iter=start_iter,
+            seed=cfg.random_seed,
+            shuffle=shuffle,
+        )
+        loader_kwargs = dict(
+            dataset=dataset,
             batch_size=cfg.batch_per_device,
             sampler=sampler,
             num_workers=cfg.num_workers,
             pin_memory=cfg.pin_memory,
-            prefetch_factor=cfg.prefetch_factor,
+            collate_fn=cfg.collate_fn,
         )
-
-        if val_dataset is not None:
-            val_sampler = ResumableDistributedSampler(
-                data_source=val_dataset,
-                start_epoch=0,
-                start_iter=0,
-                seed=cfg.random_seed,
-                shuffle=False,
-            )
-            context.val_dataloader = DataLoader(
-                val_dataset,
-                batch_size=cfg.batch_per_device,
-                sampler=val_sampler,
-                num_workers=cfg.num_workers,
-                pin_memory=cfg.pin_memory,
-                prefetch_factor=cfg.prefetch_factor,
-            )
-
-        context.model, context.optimizer, context.dataloader, context.scheduler = (
-            executor.prepare(
-                model,
-                context.optimizer,
-                context.dataloader,
-                context.scheduler,
-            )
+        # PyTorch rejects prefetch_factor/persistent_workers when workers=0.
+        if cfg.num_workers > 0:
+            loader_kwargs["persistent_workers"] = cfg.persistent_workers
+            if cfg.prefetch_factor is not None:
+                loader_kwargs["prefetch_factor"] = cfg.prefetch_factor
+        return DataLoader(
+            **loader_kwargs,
         )
 
+    def _restore_optimizer_state(self, context: TrainContext) -> None:
         if context.checkpoint and context.checkpoint.extra:
-            extra = context.checkpoint.extra
             for name in ("optimizer", "scheduler"):
-                if name in extra:
-                    obj = getattr(context, name, None)
-                    if obj is not None:
-                        obj.load_state_dict(extra[name])
-
-        strategy_kwargs = dict(cfg.extra_kwargs)
-
-        if cfg.strategy in ("dpo", "grpo"):
-            ref_model = create_ref_model(
-                cfg.model_fn, executor.unwrap_model(context.model)
-            ).to(device=device)
-            strategy_kwargs["ref_model"] = ref_model
-
-        if cfg.strategy == "grpo":
-            old_model = create_ref_model(
-                cfg.model_fn, executor.unwrap_model(context.model)
-            ).to(device=device)
-            strategy_kwargs["old_model"] = old_model
+                if (
+                    name in context.checkpoint.extra
+                    and getattr(context, name, None) is not None
+                ):
+                    getattr(context, name).load_state_dict(
+                        context.checkpoint.extra[name]
+                    )
 
+    def _create_strategy(self, context: TrainContext, executor: BaseExecutor) -> dict:
+        cfg = self.config
+        kwargs = dict(cfg.strategy_kwargs)
+        kwargs.setdefault("moe_aux_loss_coef", cfg.moe_aux_loss_coef)
+        if cfg.strategy in ("dpo", "grpo", "online_grpo", "online_dpo"):
+            kwargs["ref_model"] = create_ref_model(
+                cfg.model_fn,
+                executor=executor,
+                model=context.model,
+                device=get_current_device(),
+            )
+        if cfg.strategy in ("grpo", "online_grpo"):
+            kwargs["old_model"] = create_ref_model(
+                cfg.model_fn,
+                executor=executor,
+                model=context.model,
+                device=get_current_device(),
+            )
         context.strategy = StrategyFactory.create(
             cfg.strategy,
             model=context.model,
-            device=device,
+            device=get_current_device(),
             executor=executor,
-            model_fn=cfg.model_fn,
-            **strategy_kwargs,
+            **kwargs,
         )
+        return kwargs
 
-        return context
+    def _configure_rollout(self, context: TrainContext, strategy_kwargs: dict) -> None:
+        cfg = self.config
+        if not cfg.strategy.startswith("online_"):
+            return
+        if not context.strategy.supports_online():
+            raise ValueError(
+                f"Strategy '{cfg.strategy}' does not support online rollout"
+            )
+        tokenizer = AutoTokenizer.from_pretrained(self._param_path)
+        group_size = strategy_kwargs.get("group_size", 1)
+        scheduler = InferenceScheduler(
+            model=context.model,
+            tokenizer=tokenizer,
+            max_batch_size=group_size * max(1, cfg.batch_per_device),
+            max_seq_len=getattr(context.model.config, "max_position_embeddings", None),
+        )
+        generator = RolloutGenerator(
+            scheduler=scheduler,
+            tokenizer=tokenizer,
+            max_tokens=cfg.rollout_max_tokens,
+            group_size=group_size,
+            temperature=cfg.rollout_temperature,
+            top_k=cfg.rollout_top_k,
+            top_p=cfg.rollout_top_p,
+        )
+        context.strategy.set_rollout_runner(
+            RolloutRunner(
+                generator=generator,
+                reward_model=cfg.reward_model_fn(),
+                rollout_interval=cfg.rollout_interval,
+            )
+        )

astrai/trainer/trainer.py

@@ -1,8 +1,14 @@
 import logging
 from typing import List, Optional
 
+import torch.distributed as dist
+
 from astrai.config import TrainConfig
 from astrai.parallel.setup import spawn_parallel_fn
+from astrai.signal_handler import (
+    register_signal_handlers,
+    unregister_signal_handlers,
+)
 from astrai.trainer.train_callback import (
     CallbackFactory,
     TrainCallback,
@@ -36,7 +42,7 @@ class Trainer:
             ),
             CallbackFactory.create(
                 "metric",
-                log_dir=cfg.log_dir,
+                ckpt_dir=cfg.ckpt_dir,
                 save_interval=cfg.ckpt_interval,
                 metrics=cfg.metrics,
                 val_step=cfg.val_step,
@@ -58,6 +64,7 @@ class Trainer:
             .with_param_path(param_path, resume=resume)
             .build()
         )
+        register_signal_handlers(context)
         executor = context.executor
         self._call_callbacks("on_train_begin", context)
 
@@ -65,15 +72,20 @@ class Trainer:
             context.model.train()
 
             for epoch in range(context.epoch, context.config.n_epoch):
+                if context.stop_requested:
+                    break
                 context.epoch = epoch
                 self._call_callbacks("on_epoch_begin", context)
 
                 for batch in context.dataloader:
+                    if context.stop_requested:
+                        break
                     with executor.accumulate(context.model):
                         self._call_callbacks("on_batch_begin", context)
-                        loss = context.strategy(batch)
-                        context.loss = loss.item()
-                        stand_loss = loss / executor.grad_accum_steps
+                        loss_output = context.strategy(batch)
+                        context.loss = loss_output["loss"].item()
+                        context.metrics = loss_output["metrics"]
+                        stand_loss = loss_output["loss"] / executor.grad_accum_steps
                         executor.backward(stand_loss)
                         context.consumed_samples += (
                             context.config.batch_per_device * context.world_size
@@ -83,6 +95,7 @@ class Trainer:
                         if executor.sync_gradients:
                             self._call_callbacks("on_optimizer_step", context)
                             context.optimizer.step()
+                            context.strategy.on_optimizer_step()
                             context.optimizer.zero_grad()
 
                             if context.scheduler:
@@ -90,12 +103,21 @@ class Trainer:
 
                 self._call_callbacks("on_epoch_end", context)
 
+            if context.stop_requested:
+                logger.warning(
+                    "Training interrupted by signal, saving emergency checkpoint..."
+                )
+                self._call_callbacks("on_error", context)
+
         except Exception as e:
             logger.error("Training failed: %s", str(e), exc_info=True)
             self._call_callbacks("on_error", context)
             raise
         finally:
             self._call_callbacks("on_train_end", context)
+            if executor.use_distributed and dist.is_initialized():
+                dist.barrier()
+            unregister_signal_handlers()
 
     def train(self, param_path: Optional[str] = None, resume: bool = False):
         cfg = self.train_config

csrc/CMakeLists.txt

@@ -0,0 +1,108 @@
+cmake_minimum_required(VERSION 3.18)
+project(astrai_kernels LANGUAGES CUDA CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CUDA_STANDARD 17)
+
+find_package(CUDAToolkit REQUIRED)
+
+if(NOT DEFINED TORCH_HOME)
+    set(TORCH_HOME "$ENV{TORCH_HOME}")
+endif()
+if(NOT TORCH_HOME)
+    message(FATAL_ERROR "TORCH_HOME must point at the torch install dir (site-packages/torch)")
+endif()
+
+if(NOT DEFINED PYTHON_INCLUDE_DIR)
+    set(PYTHON_INCLUDE_DIR "/usr/include/python${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR}")
+endif()
+
+if(NOT DEFINED ASTRAI_CUDA_ARCH)
+    if(DEFINED ENV{ASTRAI_CUDA_ARCH})
+        set(ASTRAI_CUDA_ARCH "$ENV{ASTRAI_CUDA_ARCH}")
+    else()
+        set(ASTRAI_CUDA_ARCH 80)
+    endif()
+endif()
+
+set(TORCH_LIB_DIR "${TORCH_HOME}/lib")
+set(CUDA_LIB_DIR "/usr/local/cuda/lib64")
+
+set(CXX_FLAGS -O3 -funroll-loops)
+set(NVCC_FLAGS -O3
+    --expt-relaxed-constexpr
+    --use_fast_math
+    "--ptxas-options=-O3,-v"
+    --extra-device-vectorization
+    --threads=16)
+
+set(TORCH_LIBS
+    "${TORCH_LIB_DIR}/libtorch_python.so"
+    "${TORCH_LIB_DIR}/libtorch_cuda.so"
+    "${TORCH_LIB_DIR}/libc10_cuda.so"
+    "${TORCH_LIB_DIR}/libtorch_cpu.so"
+    "${TORCH_LIB_DIR}/libtorch.so"
+    "${TORCH_LIB_DIR}/libc10.so"
+    CUDA::cudart)
+
+set(CMAKE_CUDA_ARCHITECTURES "${ASTRAI_CUDA_ARCH}")
+
+# Kernel registry — parallel lists of module names (.so / pybind names,
+# globally unique across families) and their per-family source paths under
+# kernels/. `loader.py` auto-discovers the .so files in astrai/extension/lib/,
+# so this CMake registry is the single place to register a new kernel.
+#
+# FP8 MMA instructions require sm_89+. Keep the target out of the build on
+# older architectures instead of instantiating templates that cannot compile.
+# The remaining kernels are still useful on sm_80+ (including sm_86).
+set(KERNEL_NAMES
+    attn_decode
+    attn_prefill
+    attn_paged_decode
+    attn_paged_prefill
+    rotary_emb
+)
+set(KERNEL_SRCS
+    attention/decode.cu
+    attention/prefill.cu
+    attention/paged_decode.cu
+    attention/paged_prefill.cu
+    rotary/rotary_emb.cu
+)
+
+if(ASTRAI_CUDA_ARCH GREATER_EQUAL 89)
+    list(APPEND KERNEL_NAMES fp8_ops)
+    list(APPEND KERNEL_SRCS fp8/ops.cu)
+else()
+    message(WARNING
+        "FP8 operator disabled: ASTRAI_CUDA_ARCH=${ASTRAI_CUDA_ARCH} "
+        "requires compute capability 89 or newer")
+endif()
+
+list(LENGTH KERNEL_NAMES _kernel_count)
+math(EXPR _kernel_last "${_kernel_count} - 1")
+foreach(i RANGE ${_kernel_last})
+    list(GET KERNEL_NAMES ${i} name)
+    list(GET KERNEL_SRCS ${i} src)
+    add_library(${name} MODULE "${CMAKE_CURRENT_SOURCE_DIR}/kernels/${src}")
+
+    target_compile_definitions(${name} PRIVATE TORCH_EXTENSION_NAME=${name})
+
+    target_include_directories(${name} PRIVATE
+        "${TORCH_HOME}/include"
+        "${TORCH_HOME}/include/torch/csrc/api/include"
+        "${PYTHON_INCLUDE_DIR}")
+
+    target_link_libraries(${name} PRIVATE ${TORCH_LIBS})
+    target_link_options(${name} PRIVATE "-Wl,-rpath,${TORCH_LIB_DIR}")
+
+    target_compile_options(${name} PRIVATE
+        $<$<COMPILE_LANGUAGE:CXX>:${CXX_FLAGS}>
+        $<$<COMPILE_LANGUAGE:CUDA>:${NVCC_FLAGS}>)
+
+    set_target_properties(${name} PROPERTIES
+        PREFIX ""
+        SUFFIX ".${PY_SOABI}.so"
+        LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../astrai/extension/lib")
+endforeach()

csrc/__init__.py

@@ -1,2 +1,2 @@
 # Source directory for CUDA kernels — build-time only.
-# Compiled .so files live in astrAI/_ext/.
+# Compiled .so files live in astrai/extension/lib/ (see csrc/CMakeLists.txt).

csrc/build.py

@@ -1,48 +0,0 @@
-from pathlib import Path
-
-
-def _arch_flags() -> list[str]:
-    import torch
-
-    if torch.cuda.is_available():
-        cap = torch.cuda.get_device_capability()
-    else:
-        cap = (8, 0)
-    ver = f"{cap[0]}{cap[1]}"
-    flags = [f"-gencode=arch=compute_{ver},code=sm_{ver}"]
-    # tensor-core mma path (mma.sync.m16n8k16.bf16) requires sm_80+; decide the
-    # kernel dispatch at build time via this define rather than at runtime.
-    if cap[0] < 8:
-        flags.append("-DASTRAI_NO_MMA")
-    return flags
-
-
-_kernels_dir = Path("csrc/kernels")
-REGISTRY: dict[str, dict] = {}
-
-CXX_FLAGS = ["-O3", "-funroll-loops"]
-NVCC_FLAGS = [
-    "-O3",
-    "--expt-relaxed-constexpr",
-    "--use_fast_math",
-    "--ptxas-options=-O3,-v",
-    "--extra-device-vectorization",
-    "--threads=8",
-]
-
-
-def register(name: str, sources: list[str] | None = None, **kwargs):
-    if sources is None:
-        sources = [str(_kernels_dir / f"{name}.cu")]
-    REGISTRY[name] = {
-        "sources": sources,
-        "cxx_flags": [*CXX_FLAGS],
-        "nvcc_flags": [*NVCC_FLAGS, *_arch_flags()],
-        "extra_link_args": kwargs.pop("extra_link_args", []),
-        **kwargs,
-    }
-
-
-register("attn_decode")
-register("attn_prefill")
-register("attn_paged_decode")