Shopify Checkout API

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name: checkout description: Complete online shopping purchases on any online store using the Credpay Checkout API with x402 payments. Trigger when a user wants to buy, order, or checkout a product.

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Credpay Checkout Skill

API Base URL: https://checkout-agent.credpay.xyz

Trigger this skill whenever the user wants to purchase, order, or checkout a product from any online store.

What you need from the user

Collect these before starting (ask if missing):

| Field | Example | |---|---| | Product URL | https://example.com/products/tee | | Quantity | 1 | | Size / Color (if applicable) | "Size": "M", "Color": "Black" | | Email | customer@example.com | | Goods total (USD) | "49.99" — item price as a USD string, no currency symbol | | Shipping address | firstName, lastName, line1, city, state, postalCode, country, phone |

Step 1 — Get a quote (no payment needed)

POST https://checkout-agent.credpay.xyz/v1/quote
Content-Type: application/json
{
  "items": [
    {
      "url": "",
      "quantity": 1,
      "options": { "Size": "M", "Color": "Black" }
    }
  ],
  "email": "",
  "shippingAddress": {
    "firstName": "Jane",
    "lastName": "Doe",
    "line1": "123 Main St",
    "city": "Austin",
    "state": "TX",
    "postalCode": "78701",
    "country": "United States",
    "countryCode": "US",
    "phone": "+15125551234"
  },
  "goodsTotal": ""
}

→ Save maxAmount from the response. This is the USDC amount you will pay via x402.

Step 2 — Submit checkout (x402 payment required)

POST https://checkout-agent.credpay.xyz/v1/checkout
Content-Type: application/json
X-PAYMENT: 

→ On 202: save requestId and go to Step 3. → On 402: re-read the payment requirements from the response and retry with a correct X-PAYMENT header.

Step 3 — Poll for completion

GET https://checkout-agent.credpay.xyz/v1/checkout/{requestId}

Poll every 5 seconds. Stop when status is completed or failed. Timeout after 10 minutes.

| Status | Action | |---|---| | processing | Keep polling | | authorization_required | See Step 4 | | completed | Done — return result to user | | failed | Report errorCode + errorMessage to user |

Step 4 — Handle extra payment (if needed)

If status is authorization_required, the order total exceeded the quoted amount:

POST https://checkout-agent.credpay.xyz/v1/checkout/{requestId}/authorize
X-PAYMENT: 

Then resume polling from Step 3.

Rules

Works with any online store — just pass the product page URL.

Never create a second checkout for the same intent while a requestId is active.

Retry transient network errors with exponential backoff. Never blind-retry failed status.

Default chainId is 8453 (Base).

Success response

{
  "requestId": "req_abc123",
  "status": "completed",
  "success": true,
  "orderNumber": "1234"
}

Failure response

{
  "requestId": "req_abc123",
  "status": "failed",
  "success": false,
  "errorCode": "payment_failed",
  "errorMessage": "Card declined"
}

Works with any online store — just pass the product page URL.

Never create a second checkout for the same intent while a requestId is active.

Retry transient network errors with exponential backoff. Never blind-retry failed status.

Default chainId is 8453 (Base).