What the standard says
When any user interface component receives focus, it does not initiate a change of context.
Why it matters
A keyboard user tabs to explore. If tabbing onto a select box submits the form, exploring becomes dangerous.
What a failure looks like
- failsA `<select>` that navigates on focus.
- failsA field that opens a modal when focused.
How to fix it
- doAct on activation — a click, Enter, or an explicit Go button — never on focus alone.
How A11ySignal checks it
manual
No automated rule can judge this criterion, and we will not pretend otherwise. A clean scan does not mean 3.2.1 passes — it means nothing we can measure fails. This one needs a person.