fix(rq): watchdog cleanup calls abstract StartedJobRegistry.remove

[cloudiful]

AI disclosure

I encountered this issue in my deployment. This issue report was prepared with assistance from AI.

Description

The RQ watchdog cleanup path introduced for #106 calls StartedJobRegistry.remove(task_id). In current RQ 2.x, StartedJobRegistry.remove() is intentionally unimplemented and raises NotImplementedError.

With docling-jobkit==3.4.0 and rq==2.11.0, an orphaned worker is detected and the task is published as FAILURE, but cleanup then fails:

Failed to clean up RQ state for task ...
NotImplementedError

The job remains in rq:wip:{queue}, so the watchdog can rediscover it and emit repeated warnings.

Deterministic reproduction

The underlying RQ failure can be reproduced without Redis:

uv run python -c "from rq.registry import StartedJobRegistry; StartedJobRegistry(name='convert', connection=None).remove('repro-task')"

This raises NotImplementedError because StartedJobRegistry.remove() is abstract in RQ 2.x.

Watchdog reproduction

1. Run docling-jobkit 3.4.0 with RQ 2.x.
2. Let a SimpleWorker job lose its heartbeat, or reproduce the watchdog branch with a missing heartbeat key and a started-job registry entry.
3. Wait for _watchdog_task() to process the orphaned task.
4. Observe the StartedJobRegistry.remove() NotImplementedError in the cleanup traceback.

Expected behavior

The watchdog should set the RQ job to FAILED and remove its started execution entry without raising. Missing or already-expired jobs should remain a non-fatal cleanup case.

Proposed fix

Use the RQ execution-aware cleanup API, such as StartedJobRegistry.remove_executions(job), after fetching the job, and add a regression test covering the cleanup path. This is a follow-up to the implementation released for #106.

Environment

• docling-jobkit 3.4.0
• rq 2.11.0
• Python 3.12 or 3.13