Learn the ARIA contract

Before choosing a tool or writing more code, make the requirement concrete. A custom tab interface implements the complete tab pattern rather than adding role=tab to arbitrary links.

ARIA changes accessibility semantics; it does not add behavior, styling, focusability, or validation automatically. The useful target is not encyclopedic coverage. Make one deliberate choice, observe its consequences, and know which requirement would make you revise it.

A common failure is to add a role to silence an audit while leaving interaction behavior unchanged. The happy path may still work, which makes the mistake easy to miss. use an established pattern, implement its complete keyboard and state contract, and test across target technology. Keep the first version small enough that every important input and output remains visible.

This supports the module goal: Use ARIA and dynamic announcements only where native HTML cannot express the required relationship or state. Capture the request, command, trace, screenshot, test result, or other evidence that proves the result.

Choose one custom widget, list every behavior its role promises, and compare that list with the implementation. Change one condition on purpose, predict the result, and compare the prediction with what actually happened.