Cart Logic

Overview

Cart logic covers how your store manages items a shopper intends to buy: adding, removing, and updating items; persisting the cart across page loads and devices; and merging a guest cart into an account when the customer logs in. On Shopify, WooCommerce, and BigCommerce, the cart is built into the platform — the goal is to configure it correctly and extend it when needed. Custom code is only required for headless storefronts.

When to Use This Skill

• When cart state is lost when users navigate between pages (missing persistence)
• When guest cart items disappear after login (missing merge logic)
• When implementing real-time cart price updates (coupons, quantity changes, shipping estimates)
• When building a headless storefront that needs a custom cart implementation

Core Instructions

Step 1: Understand how your platform handles cart logic