- Track a heartbeat timestamp in ~/.sharedinbox-agent-heartbeat at the
start of each _run_loop() invocation so we can tell when it last ran.
- Add `agent_loop.py monitor` subcommand that exits 1 with a WARNING
message if the heartbeat is missing, corrupted, or older than 2 hours.
- Add .forgejo/workflows/monitor.yml scheduled workflow that runs the
monitor check every 2 hours on the self-hosted runner; a CI failure
serves as the warning when the loop is stalled.
- Add 7 unit tests covering all monitor / heartbeat scenarios.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>