[ahonamatata]

Problem

Screen readers could announce an interactive transcript activity but report that it had no primary action. Invoking the primary action did not move focus into controls such as Copy, Like, Dislike, or Adaptive Card inputs.

The transcript rewrite removed the guarded click handler introduced by #4041 while retaining only plain DOM Enter handling. This is a separate accessibility regression from #5865 and does not depend on that pull request.

Changes

• Restore primary-action click handling on normal and grouped active descendants.
• Reuse the existing focus-trap targets used by plain Enter.
• Add HTML integration coverage for Narrator-style and NVDA-style click events, plain Enter, Escape, and grouped activities.
• Add a changelog entry.

Validation

• npm run precommit:eslint -- src in packages/component: passed.
• npm run precommit:eslint -- src in packages/test/harness: passed.
• npm run precommit:typecheck in packages/component: passed.
• Prettier checks for changed source and HTML tests: passed.
• git diff --check: passed.
• npm test -- --testPathPattern '__tests__/html2/(transcript/navigation/focusAttachment\.screenReaderPrimaryAction|part-grouping/primaryAction)\.html$': 2 suites and 2 tests passed.

Manual testing

Edge Beta plus Narrator was unavailable in the current automation environment. Actual Narrator and NVDA validation remain unverified. The automated tests cover the documented primary-action event paths for both screen readers.