Since no one else needs to know a user's wallet relays, you can use the same relay list you used for Drafts: a private write relay only the user has access to their own things.
Mints should be a DVM. So pubkeys, not urls :)
ok, work-in-progress NIP for interoperable cashu wallets up on wikifreedia 👇
https://wikifreedia.xyz/nip-cashu-wallet/f7z.io
TL;DR: a standardized way for nostr clients to access your cashu wallet(s)
* you login into any nostr app and your balance is right there, you don't need to do anything
* you can create multiple wallets
* you can add optional passphrases if you would prefer a client to have to ask you for the passphrase before it's able to spend
Discussion
It would be cool if users could also advertise a list of trusted mints they are willing to accept funds from.
That could be the start of a mixing market. Pass around proofs from trusted mints to other people who also trust the same mints severing the IP leak when minting/melting from the mint.