cartAddItem
Adds an item to the cart via the addToCart mutation.
Adds an item to the cart via the addToCart mutation.
Apply a discount code to the cart and return the updated totals/items.
Creates a fast cart/session for a single product and returns checkout URL/encryption key.
Removes a cart line item by ID and returns the updated cart.
Updates the quantity of an existing cart line item and returns the refreshed cart snapshot.
Fetch the current cart (items, totals, coupon state) during checkout.