[harshitethic]

Reproduced failure

Lease operations sampled the clock before BEGIN IMMEDIATE. A competing writer could hold the lock until the lease expired, after which complete/heartbeat/fail still accepted the old timestamp. Claim intervals and enqueue delays also included lock-wait time.

Fix

Sample time inside the acquired write transaction. Refresh claim selection time for each cleanup candidate. Preserve owner/fence/status predicates and atomic job/event writes. No database schema migration.

Six deterministic-clock tests contend against a real SQLite writer lock. All six fail on fd5a99a and pass with the fix; rejected operations leave state/events unchanged and remain reclaimable with a fresh fence.

Verification before push

• Full 40-test suite passed on Kali/Python 3.12.14 and macOS/Python 3.14.7.
• Existing 80-job/four-process benchmark smoke passed on both machines with all jobs accounted for.
• Ruff lint, formatting and git diff --check passed.
• The cloud editor blocked the existing multiprocessing manager Unix socket; device runs supplied full verification without skipping or weakening that test.

Includes an executable failure analysis, corrected architecture notes, CodeQL workflow and 0.1.3 patch-release metadata. Existing Python 3.11–3.13 CI, packaging, benchmark smoke, lint and CodeQL must pass before merge.

Limits

Time is checked during the write transaction, not at response delivery. Process pauses, slow commits, wall-clock adjustments and external side effects remain outside hard deadline/exactly-once guarantees. This is a correctness fix, not a new performance claim.

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