fix: resolve audited dispatch, kernel, and rollout bugs

- re-register the linear family with the operator dispatcher (ASTR_OPS / op_backend / resolve)
- fix bf16 gemv misaligned-address faults and element mispairing for offset weights
- reject misaligned bf16_swiglu inputs with a clear error and fall back in the backend gate
- make the rollout reuse decision, validation, and return atomic under one policy snapshot
- add the documented post-scoring rollout version check
- derive live+1 under the scheduler lock in optimizer_step via apply_weight_update(None, ...)
- reject rollout_max_policy_lag below rollout_interval - 1 at config time
- sync gemv stream-test inputs before switching streams; drop dead loader imports

astrai/config/train_config.py

@@ -234,4 +234,15 @@ class TrainConfig(BaseConfig):
                     f"numbers of forward passes and desynchronize the "
                     f"ddp/fsdp collectives, deadlocking NCCL"
                 )
+            if (
+                self.rollout_max_policy_lag is not None
+                and self.rollout_max_policy_lag < self.rollout_interval - 1
+            ):
+                raise ValueError(
+                    f"rollout_max_policy_lag={self.rollout_max_policy_lag} "
+                    f"cannot be below rollout_interval - 1 = "
+                    f"{self.rollout_interval - 1}: the replay cache reuses "
+                    f"rollouts up to that lag, so a tighter bound guarantees "
+                    f"a fatal RolloutVersionError mid-training"
+                )
         return self

astrai/extension/backend/linear.py

@@ -6,15 +6,31 @@ selection is keyed on the decode batch size alone (M in [2, 4], where it
 sits at the HBM bandwidth floor and beat the cuBLAS small-M path on every
 measured family). Every training, prefill-sized, out-of-band, or
 unsupported call falls back to PyTorch.
+
+The family stays registered with the shared operator dispatcher, so
+``op_backend(linear=...)``, ``ASTR_OPS=linear=...``, and ``resolve`` /
+``explain`` keep working like for attention and rotary. The per-layer
+hot path only consults the dispatcher when one of those selections is
+active, keeping it free of axes dictionaries and record sorting.
 """
 
-from typing import Optional
+from typing import Any, Dict, List, Optional
 
 import torch
 import torch.nn.functional as F
 from torch import Tensor
 
-from astrai.extension.dispatch import env_mode
+from astrai.extension.dispatch import (
+    ImplRecord,
+    Spec,
+    axis,
+    env_mode,
+    env_selection,
+    get_override,
+    register_family,
+    resolve,
+    tensor_axes,
+)
 from astrai.extension.loader import is_available
 from astrai.extension.ops.gemv import bf16_gemv
 
@@ -25,6 +41,10 @@ from astrai.extension.ops.gemv import bf16_gemv
 _AUTO_GEMV_M = frozenset({2, 3, 4})
 
 
+def _torch_linear(x: Tensor, weight: Tensor, bias: Optional[Tensor] = None) -> Tensor:
+    return F.linear(x, weight, bias)
+
+
 def _inference_bf16_gemv(
     x: Tensor, weight: Tensor, bias: Optional[Tensor] = None
 ) -> Tensor:
@@ -64,6 +84,108 @@ def _gemv_capable(x: Tensor, weight: Tensor, bias: Optional[Tensor]) -> bool:
     )
 
 
+def _axes(x: Tensor, weight: Tensor, bias: Optional[Tensor] = None) -> Dict[str, Any]:
+    weight_shape = tuple(weight.shape)
+    m = 1 if x.ndim == 1 else (x.shape[0] if x.ndim == 2 else None)
+    supported_m = m is not None and 1 <= m <= 8
+    shape_matches = (
+        weight.ndim == 2
+        and x.ndim in (1, 2)
+        and bool(x.shape)
+        and x.shape[-1] == weight_shape[-1]
+    )
+    same_device = x.device == weight.device and (
+        bias is None or bias.device == x.device
+    )
+    bias_supported = bias is None or (
+        bias.ndim == 1
+        and weight.ndim == 2
+        and bias.shape[0] == weight_shape[0]
+        and bias.dtype == torch.bfloat16
+        and bias.is_contiguous()
+    )
+    capability = torch.cuda.get_device_capability(x.device) if x.is_cuda else None
+    return tensor_axes(
+        x,
+        mode=env_mode("ASTRAI_GEMV"),
+        m=m,
+        supported_m=supported_m,
+        auto_m=m in _AUTO_GEMV_M,
+        shape_matches=shape_matches,
+        same_device=same_device,
+        weight_dtype=weight.dtype,
+        x_contiguous=x.is_contiguous(),
+        weight_contiguous=weight.is_contiguous(),
+        bias_supported=bias_supported,
+        capability=capability,
+    )
+
+
+_SPEC_CAPABLE = (
+    axis("device_cuda").truthy()
+    & axis("dtype").in_(torch.bfloat16)
+    & axis("weight_dtype").in_(torch.bfloat16)
+    & axis("grad_enabled").eq(False)
+    & axis("supported_m").truthy()
+    & axis("shape_matches").truthy()
+    & axis("same_device").truthy()
+    & axis("x_contiguous").truthy()
+    & axis("weight_contiguous").truthy()
+    & axis("bias_supported").truthy()
+    & Spec.of(
+        lambda ax: ax.get("capability") is not None and ax.get("capability") >= (8, 0),
+        "capability>=sm_80",
+    )
+)
+
+_SPEC_AUTO = _SPEC_CAPABLE & axis("auto_m").truthy()
+
+
+def _linear_records() -> List[ImplRecord]:
+    mode = env_mode("ASTRAI_GEMV")
+    gemv_priority = 0 if mode == "1" else 100
+    auto_priority = 0 if mode == "auto" else 90
+    torch_priority = 0 if mode == "0" else 50
+    return [
+        ImplRecord(
+            family="linear",
+            name="gemv",
+            obj=_inference_bf16_gemv,
+            spec=_SPEC_CAPABLE,
+            available=lambda: is_available("bf16_gemv"),
+            priority=gemv_priority,
+        ),
+        ImplRecord(
+            family="linear",
+            name="auto_gemv",
+            obj=_inference_bf16_gemv,
+            spec=_SPEC_AUTO,
+            available=lambda: is_available("bf16_gemv"),
+            priority=auto_priority,
+        ),
+        ImplRecord(
+            family="linear",
+            name="torch",
+            obj=_torch_linear,
+            spec=Spec.always(),
+            priority=torch_priority,
+        ),
+    ]
+
+
+def _fallback_record() -> ImplRecord:
+    return ImplRecord(
+        family="linear",
+        name="torch",
+        obj=_torch_linear,
+        spec=Spec.always(),
+        priority=999,
+    )
+
+
+register_family("linear", _axes, _linear_records, _fallback_record)
+
+
 def linear(x: Tensor, weight: Tensor, bias: Optional[Tensor] = None) -> Tensor:
     """Apply a linear projection with safe inference-only GEMV dispatch.
 
@@ -71,12 +193,18 @@ def linear(x: Tensor, weight: Tensor, bias: Optional[Tensor] = None) -> Tensor:
     primitive can safely handle any M in ``{1, ..., 8}``, and ``auto`` (the
     default) uses GEMV for decode batches with M in ``{2, 3, 4}``.
     """
+    # Route through the shared dispatcher whenever a selection is active so
+    # explicit/context/env overrides stay honored; otherwise keep the hot
+    # path free of axes dictionaries and record sorting.
+    if get_override("linear") is not None or env_selection("linear") is not None:
+        return resolve("linear", x, weight, bias).record.obj(x, weight, bias)
+
     mode = env_mode("ASTRAI_GEMV")
     if mode != "0" and _gemv_capable(x, weight, bias):
         m = 1 if x.ndim == 1 else x.shape[0]
         if mode == "1" or m in _AUTO_GEMV_M:
             return _inference_bf16_gemv(x, weight, bias)
-    return F.linear(x, weight, bias)
+    return _torch_linear(x, weight, bias)
 
 
 __all__ = ["linear"]

astrai/extension/backend/swiglu.py

@@ -40,6 +40,11 @@ def _swiglu_capable(x: Tensor, up_weight: Tensor, gate_weight: Tensor) -> bool:
         or not x.is_contiguous()
         or not up_weight.is_contiguous()
         or not gate_weight.is_contiguous()
+        # The fused kernel reads all streams as uint4; contiguous-but-offset
+        # views are routed to the unfused chain instead of failing.
+        or (x.data_ptr() & 15) != 0
+        or (up_weight.data_ptr() & 15) != 0
+        or (gate_weight.data_ptr() & 15) != 0
         or not is_available("bf16_swiglu")
     )
 

astrai/extension/loader.py

@@ -20,11 +20,8 @@ import glob
 import importlib
 import logging
 import os
-from functools import cache
 from typing import Dict, List
 
-import torch
-
 logger = logging.getLogger(__name__)
 
 _LIB_DIR = os.path.join(os.path.dirname(__file__), "lib")

astrai/inference/scheduler.py

@@ -176,10 +176,20 @@ class InferenceScheduler:
         return self._commit_weight_version(policy_version)
 
     @_with_weight_lock
-    def apply_weight_update(self, policy_version: int, update: Callable[[], T]) -> T:
+    def apply_weight_update(
-        """Mutate shared weights and publish their version without generation."""
+        self, policy_version: Optional[int], update: Callable[[], T]
+    ) -> T:
+        """Mutate shared weights and publish their version without generation.
+
+        ``policy_version=None`` derives ``live + 1`` under the same lock, for
+        callers that only need "advance by one" (e.g. ``optimizer.step()``)
+        without a read-compute-write race on the current version.
+        """
         if not callable(update):
             raise TypeError("update must be callable")
+        if policy_version is None:
+            policy_version = self._policy_version + 1
+        else:
             self._validate_weight_version(policy_version, require_advance=True)
         self._ensure_weight_update_ready()
 

astrai/trainer/rollout.py

@@ -147,8 +147,15 @@ class RolloutGenerator:
         with self._weight_lock:
             return self.scheduler.update_weights(policy_version)
 
-    def apply_weight_update(self, policy_version: int, update: Callable[[], T]) -> T:
+    def apply_weight_update(
-        """Apply a shared-model mutation at an atomic generation boundary."""
+        self, policy_version: Optional[int], update: Callable[[], T]
+    ) -> T:
+        """Apply a shared-model mutation at an atomic generation boundary.
+
+        ``policy_version=None`` lets the scheduler derive ``live + 1`` under
+        the policy lock, closing the read-compute-write race for callers
+        that only need to advance by one.
+        """
         with self._weight_lock:
             return self.scheduler.apply_weight_update(policy_version, update)
 
@@ -424,7 +431,9 @@ class RolloutRunner:
         """Publish the shared policy's new version to the rollout backend."""
         return self.generator.update_weights(policy_version)
 
-    def apply_weight_update(self, policy_version: int, update: Callable[[], T]) -> T:
+    def apply_weight_update(
+        self, policy_version: Optional[int], update: Callable[[], T]
+    ) -> T:
         """Apply a model update and publish its version as one operation."""
         return self.generator.apply_weight_update(policy_version, update)
 
@@ -502,17 +511,34 @@ class RolloutRunner:
         """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.
+        or when the cache is empty. The reuse decision, its version
+        validation, and the returned object are all captured inside one
+        policy snapshot, so a concurrent commit, refresh, or cache clear
+        can never hand out an object the snapshot has already invalidated.
         """
         cache_key = self._batch_key(batch)
+
+        def reuse(live_version: int) -> Optional[Tuple[RolloutResult, bool]]:
+            cached = self._cache
             if (
-            self._cache is None
+                cached is None
-            or cache_key != self._cache_key
+                or self._cache_key != cache_key
                 or self._steps_since_rollout >= self.rollout_interval
             ):
+                return None
+            self._validate_policy_version(cached, live_version=live_version)
+            return cached, False
+
+        outcome = self.generator.with_policy_snapshot(reuse)
+        if outcome is not None:
+            return outcome
+
         raw = self.generator.generate(batch)
         self._validate_policy_version(raw)
         scored = self._score(raw)
+        # Post-scoring check: reward scoring may call slow external services;
+        # surface an over-lag policy move before the commit critical section.
+        self._validate_policy_version(scored)
 
         def commit(live_version: int) -> Tuple[RolloutResult, bool]:
             self._validate_policy_version(scored, live_version=live_version)
@@ -525,12 +551,3 @@ class RolloutRunner:
         # cache publication. Reward scoring itself intentionally remains
         # outside the policy lock because it may call an external service.
         return self.generator.with_policy_snapshot(commit)
-
-        cached = self._cache
-        assert cached is not None
-
-        def reuse(live_version: int) -> Tuple[RolloutResult, bool]:
-            self._validate_policy_version(cached, live_version=live_version)
-            return cached, False
-
-        return self.generator.with_policy_snapshot(reuse)

astrai/trainer/strategy.py

@@ -292,8 +292,9 @@ class BaseStrategy(ABC):
         if self._rollout_runner is None:
             return optimizer.step()
 
-        next_version = self.policy_version + 1
+        # None lets the scheduler derive live+1 under the policy lock,
-        result = self._rollout_runner.apply_weight_update(next_version, optimizer.step)
+        # avoiding a read-compute-write race on policy_version.
+        result = self._rollout_runner.apply_weight_update(None, optimizer.step)
         self._rollout_runner.step()
         return result
 

csrc/kernels/bf16_gemv.cu

@@ -52,15 +52,18 @@ __global__ void bf16_gemv_kernel(
     const int wtail_start = whead + wvecs * 8;
     const uint4* __restrict__ w4 = reinterpret_cast<const uint4*>(wrow + whead);
 
-    // x chunks pair element-for-element with the aligned weight middle. When
+    // x chunks pair element-for-element with the aligned weight middle:
-    // K % 8 == 0 every x row base shares the weight alignment, so one pure
+    // the uint4 view is rooted at ``x + whead`` (16-byte aligned by the
-    // uint4 loop covers all rows (the production case: head/tail empty, no
+    // branch guard), and each row strides by ``k / 8`` vectors because its
-    // branching inside the loop). Otherwise per-row uint4 loads are not
+    // first middle element sits ``whead`` scalars past ``row * k``. When
-    // 16-byte addressable, and scalar x pairing keeps the kernel correct for
+    // K % 8 == 0 and the weight row is already aligned (whead == 0, the
-    // any K while the weight stream stays vectorized.
+    // production case) this reduces to one pure uint4 loop with an empty
+    // head/tail. Otherwise per-row uint4 loads are not 16-byte addressable,
+    // and scalar x pairing keeps the kernel correct for any K while the
+    // weight stream stays vectorized.
     if (k % 8 == 0 &&
         ((reinterpret_cast<uintptr_t>(x) + 2u * static_cast<unsigned>(whead)) & 15u) == 0u) {
-        const auto* x4 = reinterpret_cast<const uint4*>(x);
+        const auto* x4 = reinterpret_cast<const uint4*>(x + whead);
         for (int v = threadIdx.x; v < wvecs; v += blockDim.x) {
             const uint4 wv_raw = w4[v];
             const auto* wv =
@@ -68,7 +71,7 @@ __global__ void bf16_gemv_kernel(
 #pragma unroll
             for (int row = 0; row < Rows; ++row) {
                 const uint4 xv_raw =
-                    x4[(static_cast<int64_t>(row) * wvecs) + v];
+                    x4[(static_cast<int64_t>(row) * (k / 8)) + v];
                 const auto* xv =
                     reinterpret_cast<const __nv_bfloat162*>(&xv_raw);
 #pragma unroll

csrc/kernels/bf16_swiglu.cu

@@ -170,6 +170,26 @@ torch::Tensor bf16_swiglu(
             gate_weight.is_contiguous(),
         "x and weights must be contiguous"
     );
+    // The kernel loads all three streams as uint4; contiguous-but-offset
+    // views would fault with an opaque "misaligned address" CUDA error, so
+    // reject them here with an actionable message.
+    TORCH_CHECK(
+        (reinterpret_cast<uintptr_t>(x.data_ptr()) & 15u) == 0u,
+        "bf16_swiglu requires 16-byte aligned x (storage_offset must keep "
+        "data_ptr divisible by 16); clone the tensor or use the torch path"
+    );
+    TORCH_CHECK(
+        (reinterpret_cast<uintptr_t>(up_weight.data_ptr()) & 15u) == 0u,
+        "bf16_swiglu requires 16-byte aligned up_weight (storage_offset "
+        "must keep data_ptr divisible by 16); clone the tensor or use the "
+        "torch path"
+    );
+    TORCH_CHECK(
+        (reinterpret_cast<uintptr_t>(gate_weight.data_ptr()) & 15u) == 0u,
+        "bf16_swiglu requires 16-byte aligned gate_weight (storage_offset "
+        "must keep data_ptr divisible by 16); clone the tensor or use the "
+        "torch path"
+    );
     TORCH_CHECK(
         !x.requires_grad() && !up_weight.requires_grad() &&
             !gate_weight.requires_grad(),

tests/extension/test_gemv.py

@@ -130,6 +130,7 @@ def test_bf16_gemv_small_batch_fuses_bias():
 def test_bf16_gemv_uses_current_stream():
     x = torch.randn(1536, device="cuda", dtype=torch.bfloat16)
     weight = torch.randn(256, 1536, device="cuda", dtype=torch.bfloat16)
+    torch.cuda.synchronize()
     stream = torch.cuda.Stream()
     with torch.cuda.stream(stream):
         actual = bf16_gemv(x, weight)
@@ -171,6 +172,43 @@ def test_bf16_gemv_handles_unaligned_k(n, k):
     torch.testing.assert_close(actual3, F.linear(x3, weight), rtol=0.02, atol=0.5)
 
 
+@skip_no_gemv
+@pytest.mark.parametrize("m", [1, 2, 3, 4])
+def test_bf16_gemv_accepts_complementary_misalignment(m):
+    """Misaligned weight rows plus an x base chosen so the vectorized branch
+    is entered with a non-16B-aligned ``x`` pointer (regression: the branch
+    guard checked ``x + whead`` alignment but the uint4 view was rooted at
+    ``x`` itself, faulting with a misaligned-address CUDA error)."""
+    torch.manual_seed(37)
+    n, k = 256, 1536
+    # offset 5 elements = +10 bytes: weight rows land at 10 % 16 (whead=3)
+    # and x at 10 % 16, so (x + 2*whead) % 16 == 0 selects the fast path.
+    big_w = torch.randn(n * k + 8, device="cuda", dtype=torch.bfloat16)
+    weight = big_w[5 : 5 + n * k].view(n, k)
+    big_x = torch.randn(m * k + 8, device="cuda", dtype=torch.bfloat16)
+    x = big_x[5 : 5 + m * k].view(m, k) if m > 1 else big_x[5 : 5 + k]
+    assert (x.data_ptr() & 15) == 10 and (weight.data_ptr() & 15) == 10
+
+    actual = bf16_gemv(x, weight)
+    expected = F.linear(x, weight)
+    torch.testing.assert_close(actual, expected, rtol=0.02, atol=0.5 if m > 1 else 0.25)
+
+
+@skip_no_gemv
+def test_bf16_gemv_scalar_path_handles_misaligned_weight_only():
+    """Weight rows misaligned while x stays 16B-aligned take the scalar-x
+    middle and must stay exact."""
+    torch.manual_seed(41)
+    n, k = 256, 1536
+    big_w = torch.randn(n * k + 8, device="cuda", dtype=torch.bfloat16)
+    weight = big_w[5 : 5 + n * k].view(n, k)
+    x = torch.randn(2, k, device="cuda", dtype=torch.bfloat16)
+    assert (weight.data_ptr() & 15) == 10 and (x.data_ptr() & 15) == 0
+
+    actual = bf16_gemv(x, weight)
+    torch.testing.assert_close(actual, F.linear(x, weight), rtol=0.02, atol=0.5)
+
+
 @skip_no_gemv
 def test_bf16_gemv_small_batch_cuda_graph_replay():
     torch.manual_seed(31)

tests/extension/test_linear_dispatch.py

@@ -7,6 +7,7 @@ import torch.nn.functional as F
 
 from astrai.extension import is_available, linear
 from astrai.extension.backend import linear as public_linear
+from astrai.extension.dispatch import explain, op_backend, resolve
 
 # The package attribute ``linear`` is the dispatched function; reach the
 # module object explicitly for monkeypatching its private helpers.
@@ -166,3 +167,60 @@ def test_dispatched_linear_cuda_graph_replay(monkeypatch):
         graph.replay()
         expected = F.linear(x, weight)
     torch.testing.assert_close(actual, expected, rtol=0.02, atol=0.25)
+
+
+def test_linear_family_is_registered_with_shared_dispatcher():
+    from astrai.extension.dispatch import _FAMILIES
+
+    assert "linear" in _FAMILIES
+    x = torch.randn(2, 8)
+    weight = torch.randn(4, 8)
+    resolution = resolve("linear", x, weight)
+    assert resolution.record.family == "linear"
+    assert resolution.origin in ("chain", "fallback")
+    assert "linear" in explain("linear", x, weight)
+
+
+@skip_no_gemv
+def test_ops_env_override_forces_torch_for_capable_call(monkeypatch):
+    """ASTR_OPS=linear=torch must keep working after the M-band rewrite
+    (regression: the family was silently dropped from the dispatcher, so
+    the override warned, fell through, and the gemv kernel still ran)."""
+    monkeypatch.setenv("ASTR_OPS", "linear=torch")
+    x = torch.randn(2, 1536, device="cuda", dtype=torch.bfloat16)
+    weight = torch.randn(1536, 1536, device="cuda", dtype=torch.bfloat16)
+    with torch.no_grad():
+        assert not _routes_to_gemv(monkeypatch, x, weight)
+        torch.testing.assert_close(
+            linear(x, weight), F.linear(x, weight), rtol=0.02, atol=0.25
+        )
+
+
+@skip_no_gemv
+def test_ops_env_override_forces_gemv(monkeypatch):
+    monkeypatch.setenv("ASTR_OPS", "linear=gemv")
+    x = torch.randn(1, 1536, device="cuda", dtype=torch.bfloat16)
+    weight = torch.randn(256, 1536, device="cuda", dtype=torch.bfloat16)
+    with torch.no_grad():
+        # M=1 is outside the auto band but inside the forced gemv record.
+        assert _routes_to_gemv(monkeypatch, x, weight)
+
+
+@skip_no_gemv
+def test_op_backend_context_selects_torch(monkeypatch):
+    monkeypatch.setenv("ASTRAI_GEMV", "1")
+    x = torch.randn(2, 1536, device="cuda", dtype=torch.bfloat16)
+    weight = torch.randn(256, 1536, device="cuda", dtype=torch.bfloat16)
+    with torch.no_grad(), op_backend(linear="torch"):
+        assert not _routes_to_gemv(monkeypatch, x, weight)
+        torch.testing.assert_close(
+            linear(x, weight), F.linear(x, weight), rtol=0.02, atol=0.25
+        )
+    # The override is scoped: the forced mode applies again afterwards.
+    with torch.no_grad():
+        assert _routes_to_gemv(monkeypatch, x, weight)
+
+
+def test_op_backend_rejects_unknown_linear_handle():
+    with pytest.raises(ValueError, match="Unknown linear implementation"):
+        op_backend(linear="nonexistent").__enter__()

tests/extension/test_swiglu.py

@@ -97,3 +97,16 @@ def test_bf16_swiglu_uses_current_stream_and_cuda_graph():
 def test_bf16_swiglu_rejects_unsupported_inputs(make_args, error):
     with pytest.raises(RuntimeError, match=error):
         bf16_swiglu(*make_args())
+
+
+@skip_no_swiglu
+def test_bf16_swiglu_rejects_misaligned_storage_with_clear_error():
+    """Contiguous-but-offset views must fail the wrapper's TORCH_CHECK with
+    an actionable message instead of a sticky CUDA misaligned-address error
+    (regression: the kernel casts x directly to uint4 without checking)."""
+    k = 1536
+    base = torch.randn(k + 1, device="cuda", dtype=torch.bfloat16)
+    x = base[1:]  # +2 bytes: contiguous but not 16B-aligned
+    weights = torch.randn(8, k, device="cuda", dtype=torch.bfloat16)
+    with pytest.raises(RuntimeError, match="16-byte aligned"):
+        bf16_swiglu(x, weights, weights)

tests/extension/test_swiglu_dispatch.py

@@ -95,3 +95,22 @@ def test_auto_uses_unfused_chain_until_shape_is_qualified(monkeypatch):
         actual = swiglu(x, up_weight, gate_weight)
         expected = reference_swiglu(x, up_weight, gate_weight)
     torch.testing.assert_close(actual, expected, rtol=0.03, atol=0.1)
+
+
+@skip_no_swiglu
+def test_mode_one_falls_back_for_misaligned_storage(monkeypatch):
+    """Contiguous-but-offset views must route to the unfused torch chain
+    even with ASTRAI_SWIGLU=1 instead of reaching the uint4-only kernel
+    (regression: the fused primitive faulted with a misaligned-address
+    CUDA error for such inputs)."""
+    monkeypatch.setenv("ASTRAI_SWIGLU", "1")
+    k = 1536
+    x_base = torch.randn(2 * k + 8, device="cuda", dtype=torch.bfloat16) * 0.1
+    x = x_base[1 : 1 + 2 * k].view(2, k)
+    assert x.is_contiguous() and (x.data_ptr() & 15) != 0
+    up_weight = torch.randn(64, k, device="cuda", dtype=torch.bfloat16) * 0.02
+    gate_weight = torch.randn_like(up_weight)
+    with torch.no_grad():
+        actual = swiglu(x, up_weight, gate_weight)
+        expected = reference_swiglu(x, up_weight, gate_weight)
+    torch.testing.assert_close(actual, expected, rtol=0.03, atol=0.01)

tests/inference/test_scheduler.py

@@ -583,6 +583,32 @@ def test_scheduler_applies_weight_mutation_and_version_atomically(device):
         with pytest.raises(RuntimeError, match="optimizer failed"):
             scheduler.apply_weight_update(2, failed_mutation)
         assert scheduler.policy_version == 1
+
+        # None derives live+1 under the lock: no read-compute-write race
+        # on the current version for advance-by-one callers.
+        assert scheduler.apply_weight_update(None, mutate) == "updated"
+        assert scheduler.policy_version == 2
+    finally:
+        scheduler.stop()
+
+
+def test_scheduler_atomic_advance_survives_interleaved_publish(device):
+    """A concurrent publish between reading the live version and applying
+    the update must not fail ``require_advance`` (regression: callers
+    computed live+1 outside the lock, a TOCTOU that raised spuriously)."""
+    scheduler, _tok, _model = _make_real_scheduler(device)
+
+    try:
+        # Simulate the race directly: a version read that goes stale before
+        # apply_weight_update acquires the lock. With None the scheduler
+        # re-derives live+1 inside the critical section.
+        stale_read = scheduler.policy_version + 1
+        scheduler.update_weights(1)
+        assert stale_read == 1  # now equals live -> explicit form would raise
+        with pytest.raises(ValueError, match="must advance"):
+            scheduler.apply_weight_update(stale_read, lambda: "ok")
+        assert scheduler.apply_weight_update(None, lambda: "ok") == "ok"
+        assert scheduler.policy_version == 2
     finally:
         scheduler.stop()
 

tests/trainer/test_online_e2e.py

@@ -144,3 +144,38 @@ def test_online_rollout_end_to_end(
     checkpoint = Checkpoint.load(checkpoint_dir)
     assert checkpoint.meta["policy_version"] == 2
     assert len(created_reference_models) == 1
+
+
+def _minimal_online_config(**overrides):
+    """A TrainConfig for online GRPO that only needs field overrides."""
+    defaults = dict(
+        strategy="online_grpo",
+        model_fn=lambda: torch.nn.Linear(2, 2),
+        dataset=InstructionDataset(),
+        optimizer_fn=lambda m: torch.optim.SGD(m.parameters(), lr=0.0),
+        scheduler_fn=lambda o: SchedulerFactory.create(
+            "cosine", o, warmup_steps=1, lr_decay_steps=4, min_rate=0.05
+        ),
+        reward_model_fn=LengthRewardModel,
+    )
+    defaults.update(overrides)
+    return TrainConfig(**defaults)
+
+
+def test_online_config_rejects_contradictory_policy_lag():
+    """rollout_max_policy_lag below rollout_interval - 1 guarantees a fatal
+    RolloutVersionError mid-training; it must fail at config time instead."""
+    with pytest.raises(ValueError, match="rollout_max_policy_lag=0"):
+        _minimal_online_config(rollout_interval=3, rollout_max_policy_lag=0)
+
+    # lag == interval - 1 (including the derived default) stays valid.
+    config = _minimal_online_config(rollout_interval=3, rollout_max_policy_lag=2)
+    assert config.rollout_max_policy_lag == 2
+    config = _minimal_online_config(rollout_interval=3)
+    assert config.rollout_max_policy_lag is None
+
+    # Offline strategies never consult the rollout window.
+    config = _minimal_online_config(
+        strategy="sft", rollout_interval=3, rollout_max_policy_lag=0
+    )
+    assert config.rollout_max_policy_lag == 0

tests/trainer/test_online_strategy.py

@@ -62,6 +62,9 @@ class _RecordingRunner:
 
     def apply_weight_update(self, policy_version, update):
         result = update()
+        if policy_version is None:
+            # Mirror the scheduler: None derives live+1 under the lock.
+            policy_version = self.policy_version + 1
         self.update_weights(policy_version)
         return result
 

tests/trainer/test_rollout.py

@@ -459,7 +459,7 @@ def test_rollout_runner_publishes_cache_before_concurrent_policy_update(device):
         nonlocal validation_calls
         validation_calls += 1
         original_validate(result, live_version=live_version)
-        if validation_calls == 2:
+        if validation_calls == 3:
             final_validation_started.set()
             assert allow_final_validation_to_finish.wait(timeout=5)
 
@@ -503,6 +503,58 @@ def test_rollout_runner_derives_default_policy_lag_from_interval(device):
     assert runner.max_policy_lag == 3
 
 
+def _interleave_before_snapshot(runner, callback):
+    """Wrap ``with_policy_snapshot`` so ``callback`` runs just before a
+    named snapshot callback enters the generator/scheduler locks."""
+    original_snapshot = runner.generator.with_policy_snapshot
+
+    def wrapper(inspect):
+        if inspect.__name__ == "reuse":
+            callback()
+        return original_snapshot(inspect)
+
+    runner.generator.with_policy_snapshot = wrapper
+
+
+def test_rollout_runner_reuse_reads_cache_inside_the_snapshot(device):
+    """The reuse decision must observe the cache under the policy snapshot
+    (regression: the cache was read outside the lock, so a concurrent
+    commit between the read and the lock silently handed the trainer a
+    stale rollout — a lost update)."""
+    import dataclasses
+
+    runner, _ = _make_runner(device, rollout_interval=100)
+    batch = _make_instruction_batch(n=1)
+    first, _ = runner(batch)
+    assert first.policy_version == 0
+
+    def concurrent_refresh():
+        runner.update_weights(1)
+        runner._cache = dataclasses.replace(first, policy_version=1)
+        runner._steps_since_rollout = 0
+
+    _interleave_before_snapshot(runner, concurrent_refresh)
+    result, fresh = runner(batch)
+    assert fresh is False
+    assert result is not first
+    assert result.policy_version == 1
+
+
+def test_rollout_runner_recovers_when_cache_cleared_before_reuse_snapshot(device):
+    """A cache clear between the reuse decision and the snapshot must
+    trigger a fresh rollout instead of an assertion failure (regression:
+    ``assert cached is not None`` fired because the object was captured
+    outside the lock)."""
+    runner, _ = _make_runner(device, rollout_interval=100)
+    batch = _make_instruction_batch(n=1)
+    first, _ = runner(batch)
+
+    _interleave_before_snapshot(runner, runner.clear_cache)
+    result, fresh = runner(batch)
+    assert fresh is True
+    assert result is not first
+
+
 @pytest.mark.parametrize(
     ("kwargs", "message"),
     [