[Eugene (OEvgeny)]

Fixes #4020. Continues #5867 by ahonamatata.

Changelog Entry

Fixed

• Fixed #4020, screen readers' primary action on a message not moving focus into it, in PR #6020, by @ahonamatata and @OEvgeny

Description

#4041 fixed #4020, but the transcript rewrite in #4108 dropped its click handler before either shipped (both in 4.15.0). So no release handles a screen reader's "do primary action" on a message: in Narrator scan mode or NVDA browse mode, "Click to interact." does not move into a card (also #4311). The focused message now handles that click, as #4041 did, and moves focus inside the message or group.

Design

• A click handler on the active descendant (and the group's): the screen reader consumes ENTER in scan/browse mode, so the transcript's ENTER handler never runs. Not role="application" (Screen reader: support "do primary action" #4041's comment): it turns off browse mode for the whole transcript.
• Checked with UI Automation in Edge: the focused message now exposes Invoke, which focuses the card's text box. Checked with Narrator: in scan mode, ENTER moves into the message and ESC moves back out. Not yet checked with NVDA.

Specific Changes

• ActivityRow, PartGroupingActivity: on click, focus the focus trap's target, as ENTER does

• FocusTrap: targetRef prop for that target

• focusAttachment.screenReaderPrimaryAction.windowsNarrator.html: card active → text box focused → back after ESCAPE

• focusAttachment.screenReaderPrimaryAction.nvda.html: same, clicking inside the active descendant

• part-grouping/primaryAction.windowsNarrator.html: same for a group and its "Show less" button

• I have added tests and executed them locally

• I have added .changelog/<PR#>-<slug>.md

• I have updated documentation

Review Checklist

This section is for contributors to review your work.

• Accessibility reviewed (tab order, content readability, alt text, color contrast)
• Browser and platform compatibilities reviewed
• CSS styles reviewed (minimal rules, no z-index)
• Documents reviewed (docs, samples, live demo)
• Internationalization reviewed (strings, unit formatting)
• package.json and package-lock.json reviewed
• Security reviewed (no data URIs, check for nonce leak)
• Tests reviewed (coverage, legitimacy)

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