> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stateset.com/llms.txt
> Use this file to discover all available pages before exploring further.

# UCP Quickstart

> Run the UCP handler locally and drive one checkout from discovery to completion.

# UCP Quickstart

Run the [Universal Commerce Protocol](/stateset-ucp) handler locally and walk one full checkout:
discover, create a session, complete it.

## 1 — Run the server

```bash theme={null}
git clone https://github.com/stateset/stateset-ucp-handler.git
cd stateset-ucp-handler
UCP_REQUIRE_UCP_AGENT=false UCP_REQUIRE_REQUEST_SIGNATURE=false cargo run
# listens on http://0.0.0.0:8081
```

<Warning>
  Those two flags disable caller authentication and are for **local testing only**. In production the
  `Request-Signature` header is what authenticates writes — see the
  [integration guide](/guides/universal-commerce-protocol-handler) for the signed setup.
</Warning>

## 2 — Discover

One well-known document advertises what the merchant supports:

```bash theme={null}
curl http://localhost:8081/.well-known/ucp
```

You get back the capability list — checkout, fulfillment, discounts, orders. A client should branch
on this rather than assuming; that is the point of the discovery step.

## 3 — Create a checkout session

```bash theme={null}
curl -X POST http://localhost:8081/api/checkout-sessions \
  -H 'content-type: application/json' \
  -d '{
    "line_items": [{ "sku": "SHOE-RED-10", "quantity": 1 }],
    "currency": "USD"
  }'
```

The response carries the session `id` and its state. Update it (address, shipping option, discount
code) with `PUT /api/checkout-sessions/{id}` as many times as needed.

## 4 — Complete it

```bash theme={null}
curl -X POST http://localhost:8081/api/checkout-sessions/{id}/complete
```

Completion emits an **order webhook** — that, not the HTTP response, is the durable record of the
purchase. Check `/api/webhook-deliveries` to see it.

<Tip>
  Enable the **iCommerce backend** to make this real: the session then reserves actual inventory and
  creates an order in the embedded engine, instead of a protocol-level stub. See
  [UCP](/stateset-ucp#extensions).
</Tip>

## Verify the whole loop

```bash theme={null}
./demo_test.sh   # exercises discovery → session → complete → order
```

## Next

* [UCP](/stateset-ucp) — endpoints, extensions, and how it relates to ACP and ICP
* [Integration guide](/guides/universal-commerce-protocol-handler) — signatures, headers, production setup
* [ICP](/stateset-icp) — the superset protocol, if you need mandates and negotiation