x402 lint

Free. Check your paid x402 endpoint the way buyer agents and catalogues see it: one unpaid request, then the 402 terms against the spec (v2 header and v1 body), your catalogue listing, OFAC and stablecoin-issuer freezes, signed offers (x402 offer-receipt, verified against your did:web), and discovery files. One lint per host every 10 seconds. In CI: the GitHub Action x402 lint by alalanet. MPP endpoints (WWW-Authenticate: Payment, IETF draft-httpauth-payment) are linted too. Free, no sign-up. API: GET /v1/lint?url=…, MCP tool lint_x402_endpoint.