Fix: prevent L2 swimlane records from crossing buffers

[indigo1973]

Reserve each AICore record slot before ACK so an AICPU buffer rotation after FIN cannot redirect the completed task into the next buffer generation. Commit timestamps and task identity to the reserved address after FIN without reading the active head again.

Capture end_time immediately after task execution and before FIN. Keep the existing ACK gate responsible only for old-buffer lifetime and host collection.

Validated with the Qwen3-14B warmup-only serving workload: 860265 Prefill and 19264 Decode AICPU/AICore records matched one-to-one, with no zero start times, duplicate keys, join gaps, sequence breaks, or invalid buffer boundaries.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: b4f1c01f-33be-4637-be07-61aa7121d379

📥 Commits

Reviewing files that changed from the base of the PR and between f7909e2 and 9a4ad16.

📒 Files selected for processing (3)

• src/a2a3/runtime/host_build_graph/aicore/aicore_executor.cpp
• src/a2a3/runtime/tensormap_and_ringbuffer/aicore/aicore_executor.cpp
• src/common/platform/include/aicore/l2_swimlane_collector_aicore.h

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📝 Walkthrough

Walkthrough

The L2 swimlane recording path now separates record-slot reservation from record population. Both AICore executors reserve records before acknowledgement, capture execution end time earlier, and commit timing and task identity afterward.

Changes

L2 swimlane recording

Layer / File(s)	Summary
Split swimlane reservation and commit helpers src/common/platform/include/aicore/l2_swimlane_collector_aicore.h	Adds helpers for reserving task slots and committing timestamps and identity, while preserving l2_swimlane_aicore_record_task as a wrapper.
Host-build AICore reservation and timing integration src/a2a3/runtime/host_build_graph/aicore/aicore_executor.cpp	Reserves records before acknowledgement, captures end_time immediately after execution, and commits the reserved record after FIN handling.
Tensormap AICore reservation and FIN ordering src/a2a3/runtime/tensormap_and_ringbuffer/aicore/aicore_executor.cpp	Reserves records before acknowledgement, captures end_time before FIN, and uses the commit helper for swimlane updates.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant AICoreExecutor
  participant ReserveHelper
  participant AICPU
  participant ExecuteTask
  participant CommitHelper
  AICoreExecutor->>ReserveHelper: reserve L2 swimlane record
  AICoreExecutor->>AICPU: issue task ACK
  AICoreExecutor->>ExecuteTask: execute task
  ExecuteTask-->>AICoreExecutor: return execution result
  AICoreExecutor->>AICPU: write task FIN
  AICoreExecutor->>CommitHelper: commit reserved record with timing and identity

Loading

Poem

I’m a rabbit with records in rows,
Reserving each slot before ACK flows.
End time tucked near the task’s little run,
FIN follows neatly when work is done.
Then commit flushes data bright—
Hop, hop, swimlane, out of sight!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: preventing L2 swimlane records from crossing buffer generations.
Description check	✅ Passed	The description directly matches the implemented reserve-before-ACK and commit-after-FIN L2 swimlane flow changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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