Before you pay an x402 door, a signed record of which offer your client would sign and why. Send {"url": "https://example.com/api/thing"}, optionally with "max_usd" (your per-payment ceiling). scvd.store knocks once, writes down the accepts exactly as served, and replays the stock x402 client's own selection over them, naming the stage that decided. You get back one JSON object: the record with the accepts printed as served, a certificate with the evidence hash bound in, the public key, and a verify_url. For the human who later asks why the money went where it went. Not a promise the purchase succeeds.