A stop button is not a cancellation protocol. In a toy agent, “stop” can mean setting a boolean and waiting for the loop to exit. In a real agent, work may already be queued, claimed by another worker, inside a browser session, or waiting for an outbound side effect. If cancellation is not represented as durable state, a restart can resurrect work the operator thought they stopped. The useful question is not “did the process receive SIGTERM?” It is: Can every layer prove whether this ...