I dunno, the mint does. That's the users problem, right?
Discussion
You can't "lock" ecash to an npub if somebody else controls the mint. If each user controls the mint, then you are basically just doing a lightning transfer.
Most people are using https://mint.minibits.cash/Bitcoin
I'm trying to figure out what I'm asking for 😅😅
Right now, if Bob is without an LN address, Amethyst will say to Alice that zapping Bob is not possible right?
I'm trying to imagine how Bob can receive sats simply by receiving ecash locked to his npub over nostr DM, based upon Alice's preferred mint.