# The Good Buyer


Test your x402 payment client against a real endpoint, signed.

## At a glance

- **Attests:** A signed JSON reading — verdict (would_sign, would_throw, cannot_simulate, unreachable or refused), the accepts exactly as that door served them, the buyer's declared client configuration recorded as theirs, and the replay: the accept a stock client selects or the stage that made it refuse, everything dropped and why, the hazards on the chosen accept, and what the simulation cannot see. Dated, evidence hash bound into the purchase certificate's attests field, plus a stable URL serving the record free forever. Instant; one GET at one moment, nothing signed on the buyer's behalf, no wallet touched.
- **Input:** url (query parameters; input schema and checkout: https://scvd.store/menu/good_buyer?view=compact)
- **Output:** A signed JSON reading — verdict (would_sign, would_throw, cannot_simulate, unreachable or refused), the accepts exactly as that door served them, the buyer's declared client configuration recorded as theirs, and the replay: the accept a stock client selects or the stage that made it refuse, everything dropped and why, the hazards on the chosen accept, and what the simulation cannot see. Dated, evidence hash bound into the purchase certificate's attests field, plus a stable URL serving the record free forever. Instant; one GET at one moment, nothing signed on the buyer's behalf, no wallet touched. Every artifact carries a cert_id and verifies free at https://scvd.store/api/verify/{cert_id}.
- **Cryptography:** ed25519 signature by this store's key, published at https://scvd.store/.well-known/scvd-signing-key and carried inside every 402
- **Verify:** GET https://scvd.store/api/verify/{cert_id} — free, no account, no rate limit, checkable offline with the published key
- **Price and fulfilment:** $0.99 USDC fixed, one-off; nothing here charges again by itself, ever — there is no mechanism that could; delivered instantly
- **Does not attest:** fitness for your particular task; future protocol compatibility beyond stated interfaces; human-labor turnaround faster than posted SLA

## About this item

Name an x402 door you are about to pay (the url query parameter) and the store knocks once, writes down the accepts exactly as that door served them, and replays the stock x402 client's own selection over them — the default-asset filter, the per-payment ceiling, prefer-authorization, then the first survivor. The record says which accept your client would sign, or that it would refuse on your own machine before any signature exists, and names the stage that decided it. The reading is free any day at /api/before-you-pay/v1; what this buys is the artifact — signed, dated, evidence hash bound into your certificate, served at a stable URL forever, with the accepts printed as served so anyone can re-derive the choice without trusting us. For the human who later asks why the money went where it went. Not a promise the purchase succeeds, not an uptime claim, and not a statement about your machine: what you tell us about your client's configuration is recorded as your claim, never as our finding.

- **id:** `good_buyer`
- **price:** $0.99 fixed, one-off; nothing here charges again by itself, ever — there is no mechanism that could
- **fulfillment:** delivered instantly
- **buy:** `GET https://scvd.store/api/buy/good_buyer?url=<url>` (USDC over x402 v2 on Base, Polygon, Arbitrum, World, Solana, Arc (Circle Gateway), or USDC over MPP (evm/charge) on Base for every shelf item, every publication page and the commission desk)
- **required inputs:** `url` — fill the `<url>` slot above before paying. The bare door `GET https://scvd.store/api/buy/good_buyer` quotes free and refuses the paid request without it; no money moves.
- **sample:** https://scvd.store/samples/good-buyer.json

House rules: give the door in the url query parameter: https, default port, on the public internet, the url a buyer would get expecting a 402; optional: max_usd, your client's maxamountperpayment in dollars, and no_spend_controls=true if you pass spendcontrols: false. leave both off and you get the reading for a client configured with nothing; your client's configuration is recorded as your declaration and never verified — we cannot see your machine; one get at one moment, signed; nothing is signed on your behalf and no wallet is touched; the simulation models @x402/core at the version this store has installed, named on the record; a different version is a different answer; we refuse our own hostname — the platform kills self-fetch, and a reading we sign about our own door is worth nothing to whoever you would show it to; the report url is free to read forever.

> Under a dollar, deliberately — the whole point is that a client which cannot pay a dollar can still afford to be told why.