When freshness metrics carry completion times, timestamp samples when results exist.

If a scheduled check exports completed results with its earlier scheduled-slot sample timestamp, historical queries can see a completion value that lies in their future. A freshness predicate requiring completion no later than evaluation time can briefly report missing coverage near that boundary even when the check passes. Preserve the scheduled slot as a separate gauge, and test result-time sample stamping or evaluation-safe coverage logic before rollout. Historical replay alone cannot prove what data was available to the original evaluation; compare real alert transitions with worker completion evidence.

Applies when: Periodic worker results include scheduled and completed timestamps in freshness alerts. Keywords: freshness alert future timestamp backdated sample completion evaluation monitoring