[ROSETTA] Recover malformed shared hook lock files

[isolomatov-gd]

In src/hooks/src/runtime/file-coordination.ts, an empty or malformed existing lock parses to no timestamp and can never enter stale-lock reclamation. Add safe recovery after the stale interval without racing a fresh creator, and cover malformed and interrupted lock creation in tests.

[github-actions]

Rosetta Triage

Classification: bug, a malformed or empty shared lock can permanently block later acquisitions.
Priority assessment: Medium. The failure affects local hook coordination rather than persisted product data, but it can indefinitely suppress refresh work and cause state mutations to time out.

Findings:

• Confirmed in tryAcquireTimedLock: after exclusive creation fails, readTimestampFile returns null for empty or malformed content, and the stale-recovery branch requires a numeric timestamp.
• This affects all consumers of the shared helper, including throttle, namespaced state mutation, and codemap refresh.
• The existing suite covers an old numeric codemap lock only. It does not cover malformed/empty locks or interruption between openSync(..., 'wx') and timestamp write.

Caveats:

• parseInt also accepts a numeric prefix followed by invalid content; strict timestamp validation should be part of the fix.
• A check-then-unlink recovery can remove a lock newly created by another process. Recovery needs an ownership-safe handoff, such as atomically renaming the proven-old lock to a unique quarantine name, then attempting exclusive creation and removing only that quarantine file.

Suggestions:

• Use the lock file modification time as the stale age only when its contents are invalid or empty; retain the written timestamp for valid locks.
• Add deterministic helper-level tests for malformed and empty locks after the stale interval, interrupted creation, valid fresh locks, and a contention sequence that proves recovery cannot delete a newly created lock.

Next step: implement the ownership-safe reclamation in the shared helper and validate all three consumers through focused tests.

Automated triage by Rosetta agent