Accessibility contract testing

Core principle: treat accessibility semantics as a testable contract, not an audit checklist. A component's role, accessible name, focus behavior, state, and AT-visibility are API surface for assistive technology and role-based tests.

Use this skill when UI refactors keep preserving pixels while breaking semantics: an unnamed modal, a styled div pretending to be a button, a combobox whose selected option is no longer exposed, or tabs that visually switch panels without updating ARIA state.

The contract

Lock only semantics users and automation rely on: