This skill should be used when the user asks to "run sentinel", "check project health", "scan for drift", "detect stale artifacts", "run perceive-decide-act cycle", or "audit pipeline state". It executes a full sentinel cycle (perceive-decide-act) with zero LLM cost to detect stale artifacts, missing files, health regression, and drift from constitution principles. Use this skill whenever the user mentions sentinel, health check, drift detection, or pipeline audit.