Cart Lifecycle

A Commerce cart progresses through distinct stages: creation, mutation, rendering, and completion.

States

State	Description
open	Active cart, can be modified
completed	Cart has been completed (order created)
rejected	Not actively used. Carts are generally retained for a limited time before automatically removed

Creating a Cart

Carts are created via the Create Cart endpoint with a profile key and locale:

POST /ingress/commerce/carts
Content-Type: application/json

{
  "profileKey": "default",
  "locale": "sv_SE"
}

The profile key determines the cart's currency, default country, and allowed shipping countries. The locale must be configured in the system registry.

The response contains the new cartId — all subsequent operations use this ID.

Mutating a Cart

Cart mutations are performed via the Commerce ingresses. Most mutations return the rendered cart.

Adding and Managing Items

# Add an item
POST /ingress/commerce/carts/{cartId}/add-item
{ "productNumber": "TSHIRT-001", "quantity": 2 }

# Change quantity
POST /ingress/commerce/carts/{cartId}/set-quantity
{ "cartItemId": "...", "quantity": 3 }

# Remove an item
POST /ingress/commerce/carts/{cartId}/remove-item
{ "cartItemId": "..." }

Setting Customer Details

# Set email
POST /ingress/commerce/carts/{cartId}/email
{ "email": "customer@example.com" }

# Set shipping address
POST /ingress/commerce/carts/{cartId}/address
{ "address": { "countryCode": "SE", "city": "Stockholm", ... } }

Custom Fields

Custom fields allow PSP apps and other integrations to store metadata on the cart:

# Set a custom field
POST /ingress/commerce/carts/{cartId}/set-field/paymentProvider
{ "value": "stripe" }

# Remove a custom field
POST /ingress/commerce/carts/{cartId}/remove-field/paymentProvider

Custom fields appear in the rendered cart under the fields property.

Rendering

Every mutation endpoint returns the rendered cart — a normalized structure with computed prices, totals, and tax. The rendering pipeline:

1. Sends a complete message to the cart actor in preview mode (no persistent changes)
2. This triggers all order creation rules (including price lookup, discounts, shipping)
3. Queries the preview result for order totals and line items
4. Maps the data into the rendered cart structure

The rendered cart includes:

• orderTotal, orderTaxTotal, shippingTotal, productTotal — computed totals
• items[] — each item with unitPrice, total, tax, discount
• fields — custom fields set via the set-field endpoint
• cartState — current state (open, completed, rejected)

After rendering, the OnCartMutation hook fires, enabling other apps to react. See Hooks.

Real-Time Updates

Subscribe to the Cart Events SSE endpoint to receive the rendered cart in real-time whenever the cart state changes:

const eventSource = new EventSource(
  `${baseUrl}/ingress/commerce/carts/${cartId}/events`
)

eventSource.onmessage = (event) => {
  const cart = JSON.parse(event.data)
  updateUI(cart)
}

This is essential for checkout flows where the cart may be modified by background processes (e.g., PSP synchronization).

Completing a Cart

Cart completion is typically triggered by a PSP app after payment authorization. The PSP app:

1. Creates a Payment actor with an authorization
2. Links the payment to the cart via a createRelation command
3. Sends a complete message to the cart ticket actor

When a cart is completed:

• The cart-to-order rule fires, creating a real order from the cart's preview
• The cart state changes to completed
• The orderId and orderNumber become available in the rendered cart
• SSE subscribers receive the final cart state

See PSP Integration for the recommended completion pattern.

Cart Profiles

Cart profiles are configured in the Commerce app registry under apps/commerce/profiles/{key}. Each profile defines:

Setting	Description
currencyCode	Currency for the cart (e.g., SEK, EUR)
defaultCountryCode	Default shipping country
allowedCountries	List of allowed shipping country codes
channelKey	Sales channel key for the order

Retrieve available profiles via the Get Cart Profiles endpoint.