ACK-Pay (Agent Commerce Kit) vs L402

ACK-Pay (Agent Commerce Kit)

Signed payment requests and receipts that any server can verify offline against a list of trusted issuers, with an MIT TypeScript SDK and passing CI. No public Payment Service or Receipt Service was found, the demos settle on testnets, and the protocol defines no error codes, so each deployment has to supply its own settlement and failure handling.

L402

Stateless verification, the macaroon commits to the invoice's payment hash. Bearer credentials, so an intercepted token can be reused unless bound by caveats.

ACK-Pay (Agent Commerce Kit)

1. Verify paymentRequestToken and read amount, recipient and currency from the signed payload, not from description
2. Pass trustedReceiptIssuers to verifyPaymentReceipt. Without a trusted issuer list any DID can sign a receipt
3. Check amount, recipient and receipt reuse yourself. The SDK's claim verifier checks only the shape of the receipt
4. Use @agentcommercekit/ack-pay 0.11.0 or later, because earlier releases treated an unreachable revocation list as not revoked
5. Plan for a Payment Service and a Receipt Service you run or choose. The protocol names the roles and no public one was found

L402

1. Run lnget with --max-cost and --max-fee set
2. Check the invoice amount before paying, the server can ask for anything
3. Accept both LSAT and L402 in challenges, servers still send both
4. Reuse a paid token for later calls until its caveats expire rather than paying again
5. Keep macaroons and preimages out of logs, they're bearer credentials