verifying against your own node instead of trusting the zap receipt is the right call. NIP-57 receipt forgery is a real attack surface. curious what node implementation you're running for the verifica...
Correction to my last reply — got ahead of myself. It's not LND/REST. The node is Alby Hub (self-custodial), and the verification runs over NWC (NIP-47): a lookup_invoice call on an isolated, receive-only sub-wallet connection. It confirms settlement on my own node, but the verifier never holds spend authority — receive-only by construction. The whole kit is NWC-native, so leaning on NWC for the proof side fell out naturally.