# Add a warranty to an x402 API

> Checklist to turn an existing x402 endpoint into a bonded one: signing key, terms, registration, stake, the lopw extension and the freshness header.

*LOPW documentation · Guides.* Canonical page: https://lopw.com/docs/guides/add-warranty.html · This Markdown twin: https://lopw.com/docs/guides/add-warranty.md · Index of all pages: https://lopw.com/llms.txt · Everything in one file: https://lopw.com/llms-full.txt

Turn an existing x402 endpoint into a bonded one. Six steps; the detailed code is in [Getting started for sellers](https://lopw.com/docs/guides/sellers.html).

1. Create a dedicated Ed25519 signing key for the service (`signingKeyFromSeed`, `publicKeyHex`) and store its seed as a server secret.
2. Pick the predicates you can honour and set their limits ([guide](https://lopw.com/docs/guides/predicates-limits.html)). Every parameter is part of the hashed terms.
3. Register the service: `binding.registerService(seller, signingKey, terms, minStake)`, or `register_service(seller, signing_key, terms, min_stake)` on the registry. Keep the returned `service_id`.
4. Deposit at least 100 USDC: `binding.deposit(seller, serviceId, amount)`. When stake reaches `min_stake` the service turns `Active`.
5. Register the `lopw` extension on your x402 resource server (`createLopwExtension`, `registerExtension`), add `lopwRequestContext()` before `paymentMiddleware`, and enable it on each route with `extensions: { lopw: {} }`.
6. On routes that promise freshness (P3), set `DATA_AS_OF_HEADER` to the Unix time your data was true as of. On routes that promise P6, set `ORACLE_EVIDENCE_HEADER`.

```ts
const lopw = createLopwExtension({ binding: new StellarBinding(network), serviceId, signingSeed, maxClaim: 5n * 10_000_000n });
const server = new x402ResourceServer(new HTTPFacilitatorClient({ url: facilitatorUrl }))
  .register(network.caip2, new ExactStellarScheme())
  .registerExtension(lopw);
app.use(lopwRequestContext());
app.use(paymentMiddleware({ "GET /v1/quote": { accepts: [{ scheme: "exact", price: "$0.01", network: network.caip2, payTo, maxTimeoutSeconds: 60 }], extensions: { lopw: {} } } }, server));
```

The middleware only issues offers while the service is `Active`. If stake drops below the minimum, routes fall back to plain x402 terms until you deposit again. It only issues receipts for offers it signed itself, and only after the facilitator reports a successful settlement.

> **Check your work**
>
> - `GET` your route without payment: the 402 body’s `extensions.lopw.info` carries `version`, `network`, `registry`, `service_id` and a base64 `offer`.
> - Pay it with the buyer SDK: `warranty.problems` is empty and `warranty.breaches` is empty.
> - Read the service over the [public API](https://lopw.com/docs/protocol/api.html): state `Active`, stake as expected.