Keysend / Spontaneous Payments Keysend lets the sender pay a destination by node pubkey without the receiver issuing a BOLT11 invoice first. The sender includes the preimage as a TLV record in the onion; receiver extracts and fulfills. Mechanism Why custom record number 5482373484? Per BOLT 1: custom records ≥ 65536 are reserved for proprietary use. The keysend type was chosen by Lightning Labs as a (large) sentinel. Limitations of bare keysend - No proof of payment : receiver gets the preimage but sender never receives a signed invoice. Some compliance / accounting flows fail. - No metadata…