Keep the cart editable and make continuity explicit
Let shoppers change the order state safely and promise cart persistence only across journeys the store actually supports.
Let shoppers edit product, variant, quantity, and removal states without rebuilding the cart. Treat cart saving as a separate promise: support only the return journeys the store can reliably restore.
Baymard's cart research supports direct quantity controls that make changes understandable.[1] Shopify's Ajax Cart API provides theme-side operations for adding, changing, updating, and clearing cart lines.[2] Those platform operations do not guarantee that every theme, app, account state, browser, or device will preserve the same cart.
The rest of this lesson is available once the Atlas is unlocked.