[combobox] accessibility: Guidance text not announced by screen readers

[grace-snow]

Bug report

Current behavior

The "Async search" variant reveals instruction text on ArrowDown, which is not announced by NVDA, JAWS or VoiceOver.

The aria-live region looks like it is being dynamically rendered instead of being dynamically populated.

Expected behavior

When instructional text appears for an input, this must be announced by screen readers.

Reproducible example

Steps to replicate:

1. Turn on a screen reader
2. Navigate to Combobox: Async search example
3. When focused on the input, use ArrowDown to make the instruction text appear visually
4. Note it is not announced by the screen reader

Base UI version

v1.2.0

Which browser are you using?

Chrome

Which OS are you using?

Windows and MacOS

Which assistive tech are you using (if applicable)?

NVDA, JAWS, VoiceOver

Additional context

Using role="alert" on the guidance text's container or pre-rendering the aria-live region should fix the announcements.

Adding an aria-describedby to the input may also improve announcements.

[linear]

BAS-447