fix: report failed rollout requests

- Return structured finish and error reasons for synchronous generation
- Reject failed online rollout batches instead of training on empty responses
- Verify allocation and extension failures release metrics and KV state

astrai/inference/__init__.py

@@ -17,11 +17,12 @@ 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
+from astrai.inference.task import STOP, GenerationResult, Task, TaskManager, TaskStatus
 
 __all__ = [
     "InferenceEngine",
     "InferenceScheduler",
+    "GenerationResult",
     "Executor",
     "STOP",
     "Task",

astrai/inference/scheduler.py

@@ -15,7 +15,13 @@ from astrai.extension import (
 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.inference.task import (
+    STOP,
+    GenerationResult,
+    Task,
+    TaskManager,
+    TaskStatus,
+)
 from astrai.model.automodel import AutoModel
 from astrai.tokenize.tokenizer import AutoTokenizer
 
@@ -317,7 +323,8 @@ class InferenceScheduler:
         frequency_penalty: float = 0.0,
         rep_window: int = 64,
         return_logprobs: bool = False,
-    ) -> List[List[int]]:
+        return_details: bool = False,
+    ) -> List[Any]:
         """Synchronous batch generation without the scheduler thread.
 
         Accepts already-tokenized prompts (no string round-trip) and runs
@@ -333,20 +340,25 @@ class InferenceScheduler:
                 parameters (uniform across the batch).
             return_logprobs: If ``True``, return ``(token_ids, logprobs)``
                 tuples per prompt (logprobs aligned 1-to-1 with token_ids).
+            return_details: If ``True``, return a structured result per prompt
+                with terminal and error reasons. Logprobs are populated when
+                ``return_logprobs`` is also ``True``.
 
         Returns:
-            ``List[List[int]]`` of generated token IDs per prompt, or —
+            Structured results when ``return_details`` is ``True``;
-            when ``return_logprobs`` is ``True`` —
+            otherwise generated token IDs per prompt, or token/logprob tuples
-            ``List[Tuple[List[int], List[float]]]``.
+            when ``return_logprobs`` is ``True``.
         """
         stop_ids = self._task_mgr.tokenizer.stop_ids
         seq_cap = self.max_seq_len
         request_backend = get_backend(use_default=False)
 
-        tasks: List[Task] = []
+        tasks: List[Optional[Task]] = []
+        error_reasons: List[Optional[str]] = []
         for ids in prompt_ids_list:
             if len(ids) >= seq_cap:
                 tasks.append(None)
+                error_reasons.append("prompt_too_long")
                 continue
             t_max = max_tokens
             if t_max is None:
@@ -355,6 +367,7 @@ class InferenceScheduler:
                 t_max = min(t_max, seq_cap - len(ids))
             if t_max <= 0:
                 tasks.append(None)
+                error_reasons.append("max_tokens_non_positive")
                 continue
             task = Task(
                 task_id=f"batch_{uuid.uuid4().hex[:8]}",
@@ -369,17 +382,22 @@ class InferenceScheduler:
             )
             if not self._task_cache.task_alloc(task.task_id, task.prompt_ids):
                 tasks.append(None)
+                error_reasons.append("kv_cache_allocation_failed")
                 continue
             task.input_tokens = len(task.prompt_ids)
             self._metrics.register(task.task_id)
             tasks.append(task)
+            error_reasons.append(None)
 
+        runtime_errors: Dict[str, str] = {}
         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)
+                    decoded, aborted = self._step(live, return_logprobs=return_logprobs)
+                    for task in aborted:
+                        runtime_errors[task.task_id] = "kv_cache_extension_failed"
                     live = [t for t in decoded if not t.is_finished(stop_ids)]
         finally:
             for t in tasks:
@@ -389,12 +407,37 @@ class InferenceScheduler:
                     )
                     self._task_cache.task_free(t.task_id)
 
-        results: List[Any] = []
+        details: List[GenerationResult] = []
-        for t in tasks:
+        for t, setup_error in zip(tasks, error_reasons):
             if t is None:
-                results.append(([], []) if return_logprobs else [])
+                details.append(
-            elif return_logprobs:
+                    GenerationResult(
-                results.append((list(t.output_ids), list(t.output_logprobs)))
+                        token_ids=[],
+                        logprobs=[],
+                        finish_reason="rejected",
+                        error_reason=setup_error,
+                    )
+                )
             else:
-                results.append(list(t.output_ids))
+                runtime_error = runtime_errors.get(t.task_id)
-        return results
+                stopped = bool(t.output_ids and t.output_ids[-1] in stop_ids)
+                if runtime_error:
+                    finish_reason = "rejected"
+                elif stopped:
+                    finish_reason = "stop"
+                else:
+                    finish_reason = "length"
+                details.append(
+                    GenerationResult(
+                        token_ids=list(t.output_ids),
+                        logprobs=list(t.output_logprobs),
+                        finish_reason=finish_reason,
+                        error_reason=runtime_error,
+                    )
+                )
+
+        if return_details:
+            return details
+        if return_logprobs:
+            return [(result.token_ids, result.logprobs) for result in details]
+        return [result.token_ids for result in details]

astrai/inference/task.py

@@ -2,8 +2,9 @@ import threading
 import time
 import uuid
 from collections import deque
+from dataclasses import dataclass
 from enum import Enum
-from typing import TYPE_CHECKING, Any, Callable, Deque, Dict, List, Optional
+from typing import TYPE_CHECKING, Any, Callable, Deque, Dict, List, Literal, Optional
 
 from tokenizers.decoders import DecodeStream
 
@@ -16,6 +17,16 @@ if TYPE_CHECKING:
 STOP = object()
 
 
+@dataclass(frozen=True)
+class GenerationResult:
+    """Structured terminal result for one synchronous generation request."""
+
+    token_ids: List[int]
+    logprobs: List[float]
+    finish_reason: Literal["stop", "length", "cancelled", "rejected"]
+    error_reason: Optional[str] = None
+
+
 class StreamDecoder:
     """Incremental decoder backed by the tokenizers library's DecodeStream.
 

astrai/trainer/rollout.py

@@ -21,6 +21,7 @@ import torch
 from torch import Tensor
 
 from astrai.inference.scheduler import InferenceScheduler
+from astrai.inference.task import GenerationResult
 
 
 @dataclass(kw_only=True)
@@ -171,21 +172,37 @@ class RolloutGenerator:
             frequency_penalty=self.frequency_penalty,
             rep_window=self.rep_window,
             return_logprobs=True,
+            return_details=True,
         )
         if len(results) != B * G:
             raise RuntimeError(
                 f"Rollout scheduler returned {len(results)} results, expected {B * G}"
             )
-        for token_ids, logprobs in results:
+        for result in results:
-            if len(token_ids) != len(logprobs):
+            if not isinstance(result, GenerationResult):
+                raise RuntimeError("Rollout scheduler returned an invalid result type")
+
+        failures = [
+            (index, result)
+            for index, result in enumerate(results)
+            if result.error_reason is not None
+            or result.finish_reason in ("cancelled", "rejected")
+        ]
+        if failures:
+            reasons = ", ".join(
+                f"request {index}: {result.error_reason or result.finish_reason}"
+                for index, result in failures
+            )
+            raise RuntimeError(f"Rollout generation failed: {reasons}")
+
+        for result in results:
+            if len(result.token_ids) != len(result.logprobs):
                 raise RuntimeError(
                     "Rollout scheduler returned misaligned token IDs and logprobs"
                 )
 
-        # Each element is (token_ids, logprobs); pad to max length.
+        # Pad successful structured results to a uniform response length.
-        max_len = 0
+        max_len = max((len(result.token_ids) for result in results), default=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
@@ -206,7 +223,8 @@ class RolloutGenerator:
         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]
+                result = results[flat_idx]
+                token_ids, lps = result.token_ids, result.logprobs
                 flat_idx += 1
                 n = len(token_ids)
                 if n:

tests/inference/test_scheduler.py

@@ -8,7 +8,7 @@ import pytest
 import torch
 
 from astrai.extension import CudaBackend, TorchNativeBackend, get_backend
-from astrai.inference import InferenceScheduler
+from astrai.inference import GenerationResult, InferenceScheduler
 from astrai.inference.metrics import MetricsCollector
 from astrai.inference.runtime.executor import DecodeSteadyState, Executor
 from astrai.inference.task import Task
@@ -372,6 +372,74 @@ def test_run_batch_too_long_prompt_skipped(device):
         scheduler.stop()
 
 
+def test_run_batch_details_distinguish_rejection_from_success(device):
+    scheduler, _tok, _model = _make_real_scheduler(device)
+    try:
+        long_prompt = list(range(100))
+        results = scheduler.run_batch(
+            [long_prompt, [10, 20]],
+            max_tokens=2,
+            temperature=0,
+            return_logprobs=True,
+            return_details=True,
+        )
+
+        assert results[0] == GenerationResult(
+            token_ids=[],
+            logprobs=[],
+            finish_reason="rejected",
+            error_reason="prompt_too_long",
+        )
+        assert results[1].finish_reason in ("stop", "length")
+        assert results[1].error_reason is None
+        assert len(results[1].token_ids) == len(results[1].logprobs)
+    finally:
+        scheduler.stop()
+
+
+def test_run_batch_details_report_non_positive_max_tokens(device):
+    scheduler, _tok, _model = _make_real_scheduler(device)
+    try:
+        result = scheduler.run_batch([[10, 20]], max_tokens=0, return_details=True)[0]
+        assert result.finish_reason == "rejected"
+        assert result.error_reason == "max_tokens_non_positive"
+    finally:
+        scheduler.stop()
+
+
+def test_run_batch_details_report_allocation_failure(device):
+    scheduler, _tok, _model = _make_real_scheduler(device)
+    try:
+        with patch.object(scheduler._task_cache, "task_alloc", return_value=False):
+            result = scheduler.run_batch([[10, 20]], max_tokens=2, return_details=True)[
+                0
+            ]
+        assert result.finish_reason == "rejected"
+        assert result.error_reason == "kv_cache_allocation_failed"
+    finally:
+        scheduler.stop()
+
+
+def test_run_batch_details_report_extension_failure_and_cleanup(device):
+    scheduler, _tok, _model = _make_real_scheduler(device)
+    try:
+        with patch.object(
+            scheduler,
+            "_step",
+            side_effect=lambda tasks, **_kwargs: ([], list(tasks)),
+        ):
+            result = scheduler.run_batch([[10, 20]], max_tokens=2, return_details=True)[
+                0
+            ]
+
+        assert result.finish_reason == "rejected"
+        assert result.error_reason == "kv_cache_extension_failed"
+        assert scheduler._task_cache._states == {}
+        assert scheduler._metrics._timings == {}
+    finally:
+        scheduler.stop()
+
+
 def test_decode_does_not_reuse_previous_batch_state():
     executor = object.__new__(Executor)
     executor.device = torch.device("cpu")

tests/trainer/test_rollout.py

@@ -4,6 +4,7 @@ import pytest
 import torch
 
 from astrai.inference.scheduler import InferenceScheduler
+from astrai.inference.task import GenerationResult
 from astrai.trainer.rollout import (
     BaseRewardModel,
     RawRollout,
@@ -173,6 +174,25 @@ def test_rollout_generator_logprobs_are_nonpositive(device):
             assert torch.all(lp <= 1e-5)
 
 
+def test_rollout_generator_rejects_failed_requests(device):
+    gen, _ = _make_generator(device, group_size=2, max_tokens=4)
+
+    def failed_run_batch(*_args, **kwargs):
+        assert kwargs["return_details"] is True
+        return [
+            GenerationResult([1], [-0.1], "length"),
+            GenerationResult([], [], "rejected", "kv_cache_allocation_failed"),
+        ]
+
+    gen.scheduler.run_batch = failed_run_batch
+
+    with pytest.raises(
+        RuntimeError,
+        match="Rollout generation failed: request 1: kv_cache_allocation_failed",
+    ):
+        gen.generate(_make_instruction_batch(n=1))
+
+
 def test_rollout_generator_instruction_role_mapping(device):
     """instruction -> system, input -> user, output -> assistant."""
     gen, _ = _make_generator(device, group_size=1, max_tokens=4)