Adds a variant to the cart. Creates a new line item or increases quantity if variant already in cart.
Documentation Index
Fetch the complete documentation index at: https://spreecommerce.org/docs/llms.txt
Use this file to discover all available pages before exploring further.
Publishable API key for store access
JWT token for authenticated customers
Bearer token for authenticated customers
Order token for guest access
Unique key for request idempotency.
Cart prefixed ID (e.g., cart_abc123)
item added with metadata