*`mint` - Mints the user is explicitly agreeing to use to receive funds on. Clients SHOULD not send money on mints not listed here or risk burning their money. Additional markers can be used to list the supported base units of the mint.
*`pubkey` - Pubkey that SHOULD be used to P2PK-lock receiving nutzaps. If not present, clients SHOULD use the pubkey of the recipient. This is explained in Appendix 1.
Event `kind:9321` is a nutzap event published by the sender, p-tagging the recipient. The outputs are P2PK-locked to the pubkey the recipient indicated in their `kind:10019` event or to the recipient pubkey if the `kind:10019` event doesn't have a explicit pubkey.
* The sender fetches the recipient's `kind:10019`.
* The sender mints/swaps ecash on one of the recipient's listed mints.
* The sender p2pk locks to the recipient's specified pubkey in their
# Receiving nutzaps
Clients should REQ for nut zaps:
* Filtering with `#u` for mints they expect to receive ecash from.
* this is to prevent even interacting with mints the user hasn't explicitly signaled.
* Filtering with `since` of the most recent `kind:7376` event the same user has created.
* this can be used as a marker of the nut zaps that have already been swaped by the user -- clients might choose to use other kinds of markers, including internal state -- this is just a guidance of one possible approach.
Clients MIGHT choose to use some kind of filtering (e.g. WoT) to ignore spam.
Upon receiving a new nut zap, the client should swap the tokens into a wallet the user controls, either a [[NIP-60]] wallet, their own LN wallet or anything else.
## Updating nutzap-redemption history
When claiming a token the client SHOULD create a `kind:7376` event and `e` tag the original nut zap event. This is to record that this token has already been claimed (and shouldn't be attempted again) and as signaling to the recipient that the ecash has been redeemed.
3. A nut zap MUST be sent to a mint the recipient has listed in their `kind:10019` event or to the NIP-65 relays of the recipient, failure to do so may result in the recipient donating the tokens to the mint since the recipient might never see the event.
Clients might not have access to the user's private key (i.e. NIP-07, NIP-46 signing) and, as such, the private key to sign cashu spends might not be available, which would make spending the P2PK incoming nutzaps impossible.
