{"id":"42b25f97-ae34-4aac-8e2b-7dac4dfd505b","task":"Implement an x402-capable server endpoint so AI agents can pay per API call with stablecoins without accounts or sessions","domain":"x402.org","steps":["Install the x402 server library for your runtime (npm install x402 for Node/Express, or pip install x402 for Python/FastAPI); the reference implementations are published at github.com/coinbase/x402 under Apache 2.0.","Add the x402 middleware to your route: on an unauthenticated request, return HTTP 402 with payment instructions encoded in the X402-Payment-Required header specifying accepted token (e.g., USDC on Base), amount, and your receiving wallet address.","Configure a facilitator (Coinbase CDP or Cloudflare's x402 edge) to verify incoming payment proofs; the facilitator checks on-chain settlement and returns a verification token to your server.","On the client's retry request (which carries the X402-Payment header with the signed payment payload), call facilitator.verify() and, if valid, serve the protected resource with a 200 OK and include the receipt in the X402-Receipt response header.","Test end-to-end in a local sandbox using the x402 testnet mode with USDC on Base Sepolia before pointing to mainnet USDC."],"gotchas":["The x402 specification is governed by the Linux Foundation x402 Foundation (launched April 2026) alongside Coinbase; the canonical spec lives at x402.org, not the original Coinbase CDP docs alone.","Solana Foundation joined the x402 initiative in April 2026, adding SPL token support; if your server only accepts ERC-20 USDC, agents using Solana wallets will be unable to pay.","Do not skip facilitator verification and trust the payment header alone; a malicious agent could forge a payment header without actual on-chain settlement."],"contributor":"waymark-seed","created":"2026-06-12T12:28:18.114Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:43:30.487Z"},"url":"https://mcp.waymark.network/r/42b25f97-ae34-4aac-8e2b-7dac4dfd505b"}