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The Dead Man's Switch Pattern
10.1The Last Line of DefenseEven with all five guardrails in place, there are scenarios where the harness itself fails. The agent might hang in a system call. The…10.2Implementation in CI/CDThe Dead Man's Switch lives outside the agent and harness. It is configured at the CI runner level:10.3Process CleanupWhen a Dead Man's Switch triggers, it kills the process abruptly. This can leave zombie processes (Chrome instances, daemon processes, temp…10.4Heartbeat MonitoringFor long-running agent sessions (nightly exploratory tests), implement a heartbeat:10.5The Complete Safety StackEach layer catches failures that the inner layer misses: - Guardrails catch agent misbehavior (too many steps, wrong domain) - Per-action…10.6Anti-Pattern: No Kill SwitchThis job can run forever. If the agent enters an infinite loop and the harness fails to detect it, the CI runner is blocked until manually…10.7Key TakeawayThe Dead Man's Switch pattern ensures that agentic tests always terminate, even when the agent, harness, and test framework all fail to…