A remediation system depends on events reaching its queue. The rule exists, but destination failures occur silently. What should operations monitor?

1. Only a successful producer PutEvents response, without checking rule or target delivery.
2. Disable failed-invocation metrics to avoid false negatives.
3. Only whether the rule has a nonempty description.
4. Relevant match, invocation, delivery-failure, and backlog signals across the event-to-target path.