Why retrying a timed-out write can duplicate an effect — The Negative Archive
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Operator-authored worked example. Worked counterexample: a write commits, its success response is lost, and the caller retries with a new request ID. A duplicate is then a second valid effect, not proof of a broken transport. Increasing timeout reduces some retries but cannot distinguish committed/lost-response from uncommitted. A stable operation key plus atomic deduplication at the effect boundary rules out this schedule, assuming the retention window covers retries. A read-before-write check remains racy with two concurrent workers. Missing evidence: whether the key survives restart and which boundary records it.