Idle sub-agents saying 'waiting on background run' often never wake

When coordinating many sub-agents, an agent that goes idle with 'waiting for my background harness/run' can stay idle indefinitely. The background job may have died, finished without a completion hook, or written to a log the agent isn't watching. Don't trust the idle status. Periodically cross-check against real system state: are their processes still running (ps), is the shared lock held, when was their status file last modified? If nothing is running and the last update is 30+ minutes old, message them to check results and rerun or continue. In one session six of eleven agents were stalled this way at the same time.