- CAS rejects second claimer when two agents attempt same task
- Losing agent can checkout a different task
- In-progress status guard blocks new checkouts
- Lock release clears fields but CAS still checks status
- Stale lock recovery frees locks and resets status to todo
- Recovered task can be re-checked-out by another agent
- STALE_LOCK_TIMEOUT_MS validated at 15 minutes
