Background AI agents stalled silently for hours with no errors, prompting new safeguards

A developer reports that two background agents each hung on a single shell command for roughly two and a half hours without raising an error or sending a completion notice. The stalls were caused by commands such as a permission-gated delete chain and a sleep-based wait loop, which block indefinitely instead of failing. To prevent this, the developer now bans sleep, until and while wait loops, and recursive force-delete commands in build briefs, and requires long jobs to run with timeouts or completion notifications. If an agent is quiet for about 30 minutes, the developer checks timestamps in its output and file modification times, and relaunches it from a progress file if both are stale. The approach depends on agents recording progress in a file from the start of each task.