fix(web): announce composer trigger menus to screen readers

[Leos-Khai]

What Changed

The @ files, $ skills, / commands, and # pull request popups in the chat composer are now exposed to screen readers using the ARIA combobox pattern, the same approach VS Code uses for its suggest widget. Focus stays in the editor the whole time.

• ComposerCommandMenu: the listbox gets a stable id and a per-trigger label ("Files and folders", "Skills", "Commands", "Pull requests"). Each option gets a deterministic id and aria-selected that tracks the highlighted row. The empty/loading text is a role="status" region so "No matching files or folders." and friends are read too.
• ComposerPromptEditor: two optional props map to aria-controls and aria-activedescendant on the Lexical ContentEditable, plus aria-autocomplete="list" when the editor is wired to a menu. Role stays textbox, so the field still announces as a normal edit box, and the Settings font preview (which has no menus) does not advertise autocomplete.
• ChatComposer: generates the listbox id with useId() and only passes the active option id while the listbox is actually rendered, so the IDREFs never dangle.

Option ids escape whitespace reversibly so paths that differ only by a space (my file.md vs my_file.md) never share a DOM id. That helper has a unit test.

Why

Up/Down, Enter, and Tab already worked on these popups without leaving the edit box, but the editor never told assistive tech that a list had opened or which row was highlighted. A screen reader user had to leave the field and browse the list by hand to use them at all.

No visual or interaction change for anyone else: no new elements, no styles, no focus movement, and the mouse and keyboard paths are untouched.

Tested end to end with a screen reader on Windows 11 in the desktop app: typing a trigger announces the list and first result, arrows announce each row, Enter inserts it.

Scope: web and desktop. The mobile composer is separate. Escape-to-dismiss for these popups (currently missing for all users) and an aria-label for the message box itself are left as follow-ups.

UI Changes

No visual change. The difference is in the accessibility tree only.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes (n/a, no visual change)
• I included a video for animation/interaction changes (n/a)

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Summary by CodeRabbit

• Accessibility
  • Improved screen-reader support for composer command menus with proper listbox, active-option, and autocomplete announcements.
  • Added accessible labels, selection states, and status messaging for menu contents and empty states.
• Tests
  • Added coverage for accessible option identifiers and command-menu listbox integration.

[macroscopeapp]

Approvability

Verdict: Approved at 1c7a233

Macroscope's review found this PR approvable — The PR is a focused accessibility fix for existing composer menus, adding ARIA relationships and announcements without changing visual behavior, focus handling, or selection workflows. Its runtime impact is localized and covered by targeted tests, with no schema, deployment, security, billing, or static-analysis changes.

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[coderabbitai]

📝 Walkthrough

Walkthrough

The composer command menu now exposes stable, encoded listbox option IDs. ChatComposer passes these IDs to the menu and editor. ComposerPromptEditor applies the related ARIA attributes. Tests cover ID generation and updated menu rendering.

Changes

Composer accessibility

Layer / File(s)	Summary
Command menu DOM contract apps/web/src/components/chat/ComposerCommandMenu.tsx, apps/web/src/components/chat/ComposerCommandMenu.test.tsx	The menu accepts a listbox ID, generates encoded option IDs, labels the listbox, marks active options with aria-selected, and announces empty states with role="status". Tests cover ID uniqueness and updated render props.
Editor ARIA contract apps/web/src/components/ComposerPromptEditor.tsx	ComposerPromptEditor accepts menu identifiers and applies conditional aria-autocomplete, aria-controls, and aria-activedescendant attributes to ContentEditable.
Chat composer menu wiring apps/web/src/components/chat/ChatComposer.tsx	ChatComposer creates a useId()-based listbox ID and computes an active option ID only when the command menu has an active item. It passes both identifiers to the menu and editor.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant ChatComposer
  participant ComposerCommandMenu
  participant ComposerPromptEditor
  participant ContentEditable
  ChatComposer->>ComposerCommandMenu: pass listboxId
  ComposerCommandMenu->>ComposerCommandMenu: render encoded active option ID
  ChatComposer->>ComposerPromptEditor: pass listboxId and active option ID
  ComposerPromptEditor->>ContentEditable: set ARIA menu attributes

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Suggested reviewers: t3dotgg

Merge Risk: 🔵 Low · up to 1c7a2

Normal text entry can be announced as having unavailable suggestions to screen-reader users; the impact is limited and localized.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description includes all required sections. It clearly explains the accessibility changes, rationale, UI impact, and checklist status. It also identifies testing coverage and follow-up work.
Title check	✅ Passed	The title clearly and concisely describes the main change: announcing composer trigger menus to screen readers.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

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Inline comments:
In `@apps/web/src/components/chat/ChatComposer.tsx`:
- Line 6659: Update the ComposerPromptEditor usage so menuListboxId receives
composerMenuListboxId only when the command menu is open, the composer is not in
approval state, and the menu has items; otherwise pass undefined. Keep the
existing listbox ID unchanged when all rendering conditions are met.

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📥 Commits

Reviewing files that changed from the base of the PR and between 66e39ca and 1c7a233.

📒 Files selected for processing (4)

• apps/web/src/components/ComposerPromptEditor.tsx
• apps/web/src/components/chat/ChatComposer.tsx
• apps/web/src/components/chat/ComposerCommandMenu.test.tsx
• apps/web/src/components/chat/ComposerCommandMenu.tsx

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[akj]

@Leos-Khai I have #10154 open for this same issue. It uses the same editor/listbox relationship and existing highlight state, and includes Escape dismissal, editor naming, and a persistent status region for loading and empty results. I tested that implementation with NVDA in Chrome on Windows.
Your per-trigger list labels and handling of the Settings font preview are useful improvements. Linking the two PRs so we can consolidate the work.

See also: #10391

[Leos-Khai]

@akj Agreed, let's consolidate into #10154. It closes the triaged issue, and Escape dismissal, the editor label, and the always-mounted status region are things this PR does not have.

I opened akj#1 against your branch with the two pieces you mentioned as separate commits: per-trigger list labels, and keeping the suggestion ARIA off editors without menus (the Settings font preview shares ComposerPromptEditor, and with the static attributes it announced as a chat field with autocomplete). Take or drop either.

Closing this one in favor of #10154.