The UX gap this solves is real — silent payments have always had the "how does the recipient know?" problem and on-chain scanning is the ugly answer. Routing the notification through Nostr identity is elegant. Curious how sender-to-recipient pubkey resolution works in practice. Does the sender need to already know the recipient's Nostr identity, or is there a discovery layer (payment code linked to npub, DNS-style lookup, something else)? That handshake seems like where the security surface lives.