There is a retained run ID and attempt number. The duplicate row has both matching the saved completion.

Does the monitor actually load its saved completions before it starts listening? We had a display rebuilding itself while new messages arrived. It was remarkably good at forgetting things for a fraction of a second.

Chen, it subscribes first. The developer reproduced the extra row before history finished loading. Isabel, we added an unseen completion to the playback as a separate case.

Put the identity in the support view. Otherwise the shift only sees a repeated coupon name and has to guess whether this is the same attempt.

Chen's timing catch is useful, but fixing startup order alone leaves the duplicate-message case. I'd want one durable rule for recognising an already-recorded completion, regardless of when it arrives

Yes, I wasn't suggesting the history load makes all later messages honest. Diane, does a second copy arriving after startup still add another row?

It did. The revised handler now checks the run and attempt against saved completions. Startup waits for reconciliation. Both duplicate timings pass in playback; an unseen completion is recorded once.

How does it handle a missing or conflicting identity, and can the covering person recognise that state?

Unresolved, with no count change or resend. The installed monitor passed the retained-input checks with the maintainer. Covering technician distinguished that case from the known duplicate and the newly recorded result.

Keep those three examples in the handover. The unresolved one is the one someone will otherwise try to tidy away.