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

# Split a cart into orders

> Complete a multi-seller cart into a group of per-seller orders with completeCartWithSplitOrdersWorkflow.

In this guide, you'll learn how the checkout split works and how to run it from
your own server code, such as a custom complete-cart route.

Mercur replaces Medusa's single-order checkout with
`completeCartWithSplitOrdersWorkflow`. It takes a cart that may hold offers from
several sellers, creates one order per seller, and wraps them in an `OrderGroup`.

## Run the workflow

```ts title="src/api/store/carts/[id]/complete/route.ts" theme={null}
import type { MedusaRequest, MedusaResponse } from "@medusajs/framework/http"
import { completeCartWithSplitOrdersWorkflow } from "@mercurjs/core/workflows"

export async function POST(req: MedusaRequest, res: MedusaResponse) {
  const { result } = await completeCartWithSplitOrdersWorkflow(req.scope).run({
    input: { cart_id: req.params.id },
  })

  res.json({ order_group_id: result.order_group_id })
}
```

The workflow is idempotent per cart: if a group already exists for the cart it
returns the existing `order_group_id` instead of splitting again. It acquires a
lock on the cart id for the duration of the split so concurrent completions can't
create duplicate orders.

<Note>
  Line items are grouped by `item.offer.seller_id`. Sellers sell against the
  shared master catalog through **offers**, so a line item's seller comes from
  its offer, never from product ownership.
</Note>

## What happens during the split

For the cart, the workflow validates payments and per-seller shipping, then in a
single transaction:

* creates the parent `OrderGroup` (`customer_id`, `cart_id`)
* creates one child `Order` per seller from that seller's items and shipping
* links each order to the group, its seller, and the originating cart
* mirrors line-item → offer links, reserves offer inventory, and splits payment captures proportionally
* refreshes commission lines per order and marks the cart `completed_at`

Finally it emits `order.placed` for the created orders and `order_group.created`
for the group.

<Tip>
  The workflow exposes hooks `validate`, `beforePaymentAuthorization`, and
  `orderGroupCreated`, so you can inject marketplace-specific logic around the
  split without forking it.
</Tip>