cart-logic

Cart persistence works by storing the cart server-side for logged-in customers and using a long-lived cart token cookie for guests. Shopify uses a 30-day cart_token cookie by default, while WooCommerce requires enabling Persistent cart under Accounts & Privacy settings.

Guest cart merge happens automatically on Shopify and WooCommerce when persistent carts are enabled. For headless builds, call Shopify's cartBuyerIdentityUpdate mutation to associate the guest cart with the customer account, and Shopify handles the merge.

Yes, Shopify's Storefront API provides cartCreate, cartLinesAdd, and cartLinesUpdate mutations for headless carts. Store the returned cart ID in a cookie or localStorage and use Cart Transform Functions for custom discounts or bundles.

Duplicate line items occur when add-to-cart logic creates a new line instead of updating an existing one. Platform-native carts handle this automatically; in headless implementations, use cartLinesUpdate to increment quantity on existing lines.

This happens when Persistent cart is disabled in WooCommerce settings. Enable it under WooCommerce, Settings, Accounts & Privacy so the cart is stored in the database and merged with the guest session on login.