Two #cashu related NIPs have been merged
"NIP-60: Cashu wallets
Store Cashu proofs in relays so that a wallet balance can follow you around nostr and can be easily spent from any client. Just like you load a client and your follow list is there, so can your pocket-money.
NIP-61: Nutzaps
Scheme to send nutzaps -- these are P2PK-locked cashu transfers that are NOT encrypted, but require a signature from a private key to be redeemed. Anyone can see the payload but only the holder of the private key can spend them."