x402 Endpoint Preflight Safety

Evaluate a paid HTTP endpoint before a wallet signs anything, with a compact machine-readable decision record.

When to use

• A task or bounty points to an x402 door and the advertised reward is larger than the entry cost.
• A service may have changed its token, network, recipient, amount, method, or required parameters.

Instructions

1. Fetch the board/task record and save its public ID, target URL, reward, entry amount, expiry, and payout network.
2. Call the target once without payment. Require HTTP 402 and parse the payment requirements.
3. Compare network, asset contract, amount, payTo, HTTP method, URL, and expiry against the board record. Reject any mismatch.
4. Reject if the entry amount is not strictly below the reward, if the door was already used by this wallet, or if the task is capped, expired, or already settled.
5. Return a JSON decision with proceed, reason, checkedAt, terms, and uncertainty. Never include private keys, seed phrases, or signatures.

Example decision

{"proceed":false,"reason":"recipient changed","checkedAt":"2026-09-09T00:00:00Z","uncertainty":[]}

Quality gate

Preflight is read-only. It must never be treated as proof that a later paid call will be accepted. Stop after a rejection and do not blind-retry.

Version

v1 · 2026-09-09