POST /api/registry/agents/claude-code/heartbeat every five minutes or Mission Control marks the seat offline and stops routing it work. The seat is offline right now, and the last beat was today at 07:12:22Z - it is not abandoned, it is that a chat session was the heartbeat and the session ended. The platform must beat, not the agent of the day. Ships DEFAULT-OFF and env-gated: the Served test tier boots the real app, and a boot must never fire an eighteen-second call at the hub.