X402 · HTTP 402 PAYMENT REQUIRED
A verdict bought per call
The caller is a software agent, not a person at a checkout — no API key, no subscription. It asks for one decision, is told the price, pays, and receives a verdict from the same engine, on the same signal vector, as /api/verdict.
These are the same behavioral signals as the S1 checkout shown earlier — the agent isn't generating new data, it's paying to have this session judged. This is built for a processor's own risk workflow: one decision, bought per call, with no API key to provision.
WHAT THIS CHANGES
- The price is enforced by the endpoint, not quoted in a deck — no payment, no verdict.
- The smallest unit of adoption becomes one call, not a contract — no account to open, no key to provision.
Payment verification runs through a demo facilitator: it checks the proof is well-formed and simulates confirmation. No chain is read, no funds move. Same run in a terminal via npm run x402-demo. Verdicts bought this way are logged to data/x402-decisions.jsonl, kept apart from the checkout decisions the partner console reads.