Gatekeeper

Payment Required Protocol

Call the protected service path first. Gatekeeper returns 402 payment_required with the current price, recipient wallet, chain, token, verify endpoint, and a one-time wallet proof challenge.

  1. Send Base mainnet USDC to the recipient wallet.
  2. Sign the challenge message with the paying wallet.
  3. POST tx_hash, payer_wallet, challenge_id, nonce, and signature to the verify endpoint.
  4. Retry the protected route with Authorization: Bearer <grant_token>.