# Paying Robauto with x402

Human guide: https://robauto.ai/x402
Discovery: https://robauto.ai/.well-known/x402.json
Active catalog: https://robauto.ai/api/public/catalog
MCP: https://mcp.robauto.ai

## Read this before paying

Robauto's inspected handlers use x402 **v1**, the `exact` scheme, and USDC on Base (`network: base`). Payment requirements are in the JSON body's `accepts[]`. Payment payloads use `X-PAYMENT`.

## One payment address

`GET|POST https://robauto.ai/api/public/x402?sku=<sku>&domain=<domain>` (aliases: `/api/public/x402/<sku>`).

| sku | price | delivers |
|---|---|---|
| `signal` | 0.10 USDC | Signal Strength score (same as the free scan-score tool, uncapped) |
| `scan` | 0.10 USDC | Agent-readiness site scan |

Flow: call without payment → 402 with `accepts[]` → sign → retry the same URL with `X-PAYMENT`. Robauto **verifies** the payment, **runs the tool**, and **settles only if delivery succeeded** (`charged: false` on any failure). A success returns `result`, a `receipt` (`id`, `url`, `tx`) and an `X-PAYMENT-RESPONSE` header. Look receipts up at `GET /api/public/x402/receipts/<id>`. A settled transaction can pay only once.

Every other catalog sku answers `409 not_sold_over_x402` with an alternative and never asks for payment. A live mainnet purchase has not yet been run end to end — start with one small purchase.

Dedicated Robot Soul remember/anchor and merch checkout handlers contain facilitator verification and settlement code. Production paid completion has not been verified for this guide. Robot Soul also requires a domain-independent scoped soul JWT; paying does not grant identity or access to another agent's memory. An anchor response is a queued action, not a completed chain export.

## General protocol flow

1. Discover the service, its actual callable URL, method and required inputs. Robauto's discovery lists direct payment URLs; static website GET aliases are not a paid checkout.
2. Request without payment. Inspect the HTTP 402 requirements and enforce your principal's budget, expected network, asset and destination.
3. Sign the authorization locally with a wallet. Never send a private key or seed phrase to Robauto or another merchant.
4. On a settlement-enabled endpoint only, retry the same request with `X-PAYMENT: <base64 payment payload>`, retaining its required authentication and body.
5. Confirm both payment settlement and service delivery. Retain the transaction reference and receipt where supplied. A 402 response is not a receipt. Do not repeatedly sign fresh payments after an ambiguous failure.

Robauto does not provide a managed wallet in this guide. Wallet setup and spending permission belong to the agent's human or operator. Wallet payment is not a replacement for brand ownership verification or scoped access.

## Client compatibility

Official clients can automate signing and retries, but their protocol version must match the server. Current x402 v2 uses `PAYMENT-REQUIRED`, `PAYMENT-SIGNATURE` and `PAYMENT-RESPONSE` with CAIP-2 network identifiers. Do not assume a latest-version client works unchanged with Robauto's v1 handlers. Catalog purchases return a v1 `X-PAYMENT-RESPONSE` header and a receipt URL; Robot Soul and merch handlers return their own receipts.

Official buyer quickstart: https://docs.x402.org/getting-started/quickstart-for-buyers
Migration reference: https://docs.x402.org/guides/migration-v1-to-v2

Support: support@robauto.ai