How the cart and checkout work
The cart lifecycle, how stock is reserved, what 'locked' means at checkout, and how coupon and voucher codes apply.
Last updated: 7 min read
Understanding the cart helps you make sense of pricing, stock, and the occasional support question. Here's what happens behind the scenes.
The cart lifecycle
- A signed-in shopper gets their open cart; a guest gets one tied to a 30-day token; otherwise a fresh cart is created.
- Adding the same item again increases its quantity rather than creating a duplicate line.
- The cart re-prices on every change, so totals always reflect current prices, discounts, and tax.
- Up to 25 coupon codes and 25 voucher codes can be applied per cart.
Locked at checkout
When a shopper starts checkout, the cart becomes locked — no more changes to items, addresses, or codes while payment is in progress. This prevents the total changing underneath a payment. Once the order is placed (or checkout is abandoned), the cart is free again.
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