A random idea to have an robust cross-clients undo-post feature: relays can implement a X minutes (e.g. 5) delay in the actual pubblication of the events, so an user can safely require the deletion (NIP-9) without worrying that the event has been already broadcasted elsewhere. Of course you have to choose a trusted outbox relay, and only use clients that support the outbox model.
Bonus side effect: this promote a slow approach to posting.
Mazin (npub18kz…x5sz) cloud fodder and 121 others (npub10np…tl5h)