Why Servers Should Own Pricing Instead of Trusting the Browser

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A point-of-sale interface previews prices in the browser so cashiers get an immediate total, but that preview should not determine what a customer owes. In the OrderRestro system, the client mirrors the pricing logic for responsiveness, while the server recalculates the final amount from trusted menu and order data when an order is submitted. Tax, discounts, and rounding are all handled on this authoritative server path. The author recommends testing by altering the submitted total, with the server either ignoring it or rejecting the mismatch, and checking edge cases such as inclusive tax, discounts, refunds, and rounding. The client-side preview still reduces friction for staff, but it does not have the final say.

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