---
name: Acceptance Criteria
description: Define done before building.
---
# Acceptance Criteria

Acceptance criteria define what "done" means, measurably, before the work starts. Without them, "is this finished?" becomes a debate at the end.

## Form (Given/When/Then)
- **Given** some starting state.
- **When** the user does X.
- **Then** Y happens (and Z does not).

Concrete examples catch ambiguity that prose hides: "Given an empty cart, when the user clicks checkout, then they see 'your cart is empty', and no request is sent to the payment API."

## Principles
- **Testable.** Each criterion maps to a check — automated or manual.
- **From the user's perspective.** Behavior, not implementation.
- **Include the negative.** What must NOT happen is as important as what must.