Challenge

An unpaid protected request receives HTTP 402 with x402 version 2 payment requirements. The challenge identifies the exact resource, USDC amount, network, asset contract, receiving wallet, and payment endpoint.

Authorization

A compatible wallet signs the payment authorization. An agent can retry programmatically; a supported browser checkout can guide a person through wallet approval.

The adapter sends the signed payment with the installation credential, authoritative rule identity, mode, and idempotency key. It does not send Coinbase facilitator credentials.

Verification and settlement

Access402 authenticates the installation, reloads the server-side rule, validates resource, amount, network, USDC asset, and project wallet, enforces account and platform limits, and reserves usage atomically.

The hosted facilitator verifies and settles. A transaction hash is recorded only after successful settlement. Reservations are released on failure, and the system fails closed when the outcome cannot be confirmed.

Access

The client retries the original request. The adapter delivers the normal resource when the paid retry or reusable grant is valid. An unpaid challenge and a failed payment do not consume plan usage.