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

# Browser Harness

> Prava's checkout automation completes a real merchant checkout and confirms the true total before charging.

The **Browser Harness** is the second half of the agentic-commerce pipeline: it **starts from a
[UCP](/integration/ucp) quote** and turns that estimate into a placed, verified order. Most merchants
don't expose a direct payment API, so to actually place an order, someone has to go through the
merchant's own checkout. The Browser Harness does exactly that: it drives the real Shopify checkout,
works out the true final total, and pays with the one-time tokenized card (a single-use stand-in
for the real card). An AI application completes the purchase without ever touching the raw card or
the merchant's checkout code.

<Note>
  The Browser Harness is the **checkout** step after a UCP [quote](/integration/ucp). It powers
  [`prava shop checkout`](/prava-pay/shopping#checkout) and hosted agentic purchases.
</Note>

## What it does

<CardGroup cols={2}>
  <Card title="Completes the real checkout" icon="cart-shopping">
    Fills the merchant's checkout (contact, shipping address, delivery option) and submits payment with
    the one-time token. No merchant integration required.
  </Card>

  <Card title="Confirms the true total first" icon="scale-balanced">
    Reconciles subtotal, shipping, and tax against the live checkout and waits for the amount to settle
    **before** charging, so there are no surprise totals.
  </Card>

  <Card title="Returns a verifiable result" icon="receipt">
    On success you get an **order id** and a payment **status**: a checkable confirmation the order was
    placed.
  </Card>

  <Card title="Reliable, repeatable" icon="arrows-rotate">
    It learns a merchant's checkout on the first run and completes later runs consistently, healing
    automatically if the page changes.
  </Card>
</CardGroup>

## Why it matters

<Steps>
  <Step title="No surprise charges">
    The amount is **reconciled and stable** before payment is attempted. If the total shifts mid-checkout
    (late shipping, tax, or add-ons), reconciliation restarts rather than charging the wrong amount.
  </Step>

  <Step title="One clean attempt">
    A checkout runs as a single, tracked flow rather than a blind retry loop, so a purchase either
    completes and returns an order, or fails cleanly for you to re-quote.
  </Step>

  <Step title="Card safety preserved">
    It pays with the **single-use, merchant-scoped** credential from the session. Even inside the
    checkout, the credential can't be reused or redirected to another merchant.
  </Step>
</Steps>

## How it fits the flow

```mermaid theme={null}
flowchart LR
    U["UCP quote<br/>price the item"]
    B["Browser Harness<br/>confirm true total"]
    R["Order placed<br/>order id + status"]
    U --> B -->|pays with one-time token| R
```

The [UCP](/integration/ucp) quote gives an estimate; the Browser Harness turns it into a **completed,
verified order**. Today it targets **Shopify** checkouts.

## Next

<CardGroup cols={2}>
  <Card title="UCP" icon="magnifying-glass" href="/integration/ucp">
    How products are discovered and quoted before checkout.
  </Card>

  <Card title="Agentic Commerce" icon="plug" href="/integration/overview">
    The full discover → quote → checkout → pay pipeline.
  </Card>
</CardGroup>