Fix: worker-chip region cleanup replay

[ccyywwen]

Summary

This PR handles the #1770 follow-up items.

Done here:

• Tighten worker-chip region cleanup shape:
  • replace defensive getattr(region, "expired", ...) with direct region.expired
  • replace defensive getattr(region, "free", None) / callable check with direct region.free()
  • update test fake regions to expose the same cleanup surface as WorkerChipOrchRegion
• Fix replay double-release:
  • add cleanup-owned chip release tracking separate from user-facing _released
  • mark chip release committed only after control_worker_chip_region_release(...) succeeds
  • allow close replay to retry native host mapping close without releasing the same chip region twice
  • add a whole-tree close regression test for mapping-close failure plus successful chip release

Already handled in #1822:

• W4 region sync/access refactor onto neutral region-native primitives
• WorkerChipOrchRegion compatibility facade over W4 region access pieces
• neutral native mapped-region backend and _region_* binding surface
• redundant provider root check cleanup in validate_single_owner_region_shape

Not done here:

• post-W4 comm_region.py hygiene
• public create_region(...)
• W5 delegated transactions
• queue/ring/mailbox/freelist templates
• Symmetric/OpenSHMEM topology

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📥 Commits

Reviewing files that changed from the base of the PR and between 87d9d0e and d812b00.

📒 Files selected for processing (4)

• python/simpler/worker.py
• python/simpler/worker_chip_orch_comm.py
• tests/ut/py/test_worker/test_comm_region.py
• tests/ut/py/test_worker/test_worker_chip_orch_comm.py

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📝 Walkthrough

Walkthrough

Worker-chip cleanup now uses public expiration state and explicit release tracking. Failed host mapping closure remains retryable, while committed chip release and region freeing occur only once. Tests cover repeated Worker.close() behavior after an initial mapping-close failure.

Changes

Worker-chip cleanup

Layer / File(s)	Summary
Cleanup state and release flow python/simpler/worker.py, python/simpler/worker_chip_orch_comm.py, tests/ut/py/test_worker/test_comm_region.py	WorkerChipOrchRegion tracks committed chip release. _close_worker_chip_region uses expired, releases chip ownership once, and frees the region after commitment. WorkerHostRegionMapping.close remains open when native closure fails.
Cleanup retry validation tests/ut/py/test_worker/test_worker_chip_orch_comm.py	The regression test verifies that repeated Worker.close() retries mapping cleanup and does not repeat L2 release.

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

Merge Risk: ⚪ Minimal · up to d812b

The PR adjusts worker-chip cleanup replay and preserves retryable host-mapping closure behavior; no actionable merge-blocking risk remains beyond normal checks and review.

Possibly related PRs

• hw-native-sys/simpler#1770: Modifies worker-chip-region cleanup and release handling.
• hw-native-sys/simpler#1689: Modifies retryable worker cleanup and failed region state.
• hw-native-sys/simpler#1822: Modifies worker and worker-chip region lifecycle handling.

Poem

A rabbit checks the closing flow,
One release marks the work complete.
Failed mappings wait and try once more,
While freed chip regions sleep neat.
Hop, hop—cleanup stays discrete!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
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.
Title check	✅ Passed	The title clearly and concisely describes the worker-chip region cleanup replay fix.
Description check	✅ Passed	The description directly explains the cleanup contract changes, replay behavior, release tracking, and regression test.

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