WooCommerce classic cart and checkout

Use this for the PHP/classic cart and shortcode checkout flow. It covers product add-to-cart customization, cart item data, calculated prices/fees, checkout fields, checkout validation, and copying cart data to orders.

It is not a Checkout Block UI skill. Some low-level cart hooks also run during Store API requests, but woocommerce_checkout_fields does not make fields appear in the Checkout Block. For block/headless cart state, use wc-store-api.

Misconception this skill corrects

"I added custom cart item data, so WooCommerce will automatically show it on the order."

Cart item data affects the cart key and lives in the cart/session. It is not automatically saved as order line-item meta. Display it with woocommerce_get_item_data, and copy it to the order line with woocommerce_checkout_create_order_line_item.

When to use this skill

Trigger when ANY of the following is true: