Add item to cart
POST/helpers/cart/add
Stateless cart helper - Adds an item to a cart and returns the updated cart with recalculated totals.
This is a pure function: (existingCart, itemToAdd) → newCart
No server-side state - Partners manage their own cart state. This endpoint simply computes the result of adding an item.
Optional - Partners can implement their own cart logic instead of using this helper.
Request
Responses
- 200
- 400
Updated cart with new item and recalculated totals
Invalid request - item not found, invalid modifiers, etc.