A canary is a limited, reversible execution with a named hypothesis, eligible scope, current approvals, accountable owner, monitoring, stop mechanism, rollback path, and review point. External participation requires the appropriate contact, consent, account, privacy, delivery, and commercial authority; internal canaries still require accurate data handling and access. The canary should isolate the smallest consequential uncertainty. It is not a quiet production launch, and it should not inherit automatic scale simply because no incident was detected.
Canary evidence records eligibility, attempted actions, completed and refused states, event quality, errors, retries, operator interventions, response burden, and unresolved records using declared denominators and authoritative sources. Negative evidence belongs in the same report: silence, failure, exclusion, ambiguous identity, missing events, rollback, or inability to complete the route can be more instructive than a clean path. Review compares the original prediction with observed behavior and chooses to stop, repair, repeat, narrow, or prepare a separately authorized next step.