Relation between Zap Request event and inbound and internal transaction events.

[rapax00]

Why?

If I send a Zap Request to URLx and I receive a Zap Receipt, it means the zap was paid correctly to URLx, but it doesn't mean that the sats were correctly transferred from URLx to the LaWallet user who was redirected to this.

I don't have an easy way to validate this. Both the Zap Request and the inbound transaction start share the same bolt11 tag value, but it isn't filterable in a Nostr relay.

Current way

The method I use to locate inbound and internal transaction events (which confirm that the sats are in the user's wallet) is by filtering based on the created_at value of the Zap Request with a small time margin before and after, and using it with the since and until parameters. I also use the authors key with the URLx public key, the p tag with the public key of the LaWallet user to whom the payment is directed, and the corresponding kind and t values.

Filter example:

{
  "authors": [
    <urlx pubkey>
  ],
  "kinds": [
    1112
  ],
  "#t": [
    "internal-transaction-start",
    "internal-transaction-ok",
    "internal-transaction-error",
    "inbound-transaction-start",
    "inbound-transaction-ok",
    "inbound-transaction-error",
  ],
  "#p": [
    <lawallet user pubkey>
  ],
  "since": <created_at of zapRequest minus 60 seconds>,
  "until": <created_at of zapRequest plus 60 seconds>
}

Suggestions

Carry e tag

The Zap Request event may have an e tag that is placed in the Zap Receipt (NIP-57).
Carry this e tag to consecutive events (inbound-transaction-start, inbound-transaction-ok, inbound-transaction-error from URLx, internal-transaction-start, internal-transaction-ok, internal-transaction-error from Ledger).

Use the id from the Zap Request in the e tag

The e tag of event A includes the id of event B, which is related to event A (NIP-01).
Use the id of the Zap Receipt in the consecutive events (same the above).