PR #27961 - manaflow-ai/cmux

Keyboard-only sidebar navigation now includes Done and Show more disclosure rows. Up/Down, Tab and Shift-Tab can focus each disclosure; Return and Space activate it through the shared SidebarFoldAction; Left/Right close or open it. Focus is kept separate from workspace selection and is cleared when a row disappears.

This is the keyboard navigation slice for the audit at e7ab659e6d23. It builds on #27671's SidebarFoldAction and deliberately leaves AXPress wiring and callback ownership to that PR.

Validation

python3 scripts/cmux-next/prepush-gate.py --commits a954126e7a1704be4d1c9d60c39ace1bc370e840..HEAD (running on the fleet lane VM; result to be recorded)
git diff --check
Added SidebarFoldKeyboardTests covering arrow/Tab reachability, Return/Space activation, directional open/close, selection preservation and stale focus cleanup.
Native Swift tests require the fleet route; no local build was run.
No screenshot is included because this is keyboard behavior and focus-state wiring; the existing disclosure row treatment remains unchanged apart from its keyboard focus ring.

Follow-up fixes (review findings)

A reload that removes the focused disclosure clears its focus and ring, so the row coming back (filter cleared) has neither, and Return does nothing until the keyboard reaches it again.
A click on Done or Show more moves keyboard focus to the clicked disclosure without a ring (as a click on a group header does), so a ring left on another disclosure can't take the next Space or Return.
Red/green: cmux-ci run --class light --script scripts/ci/package-test-lane.sh --arg=suite --arg=Packages/macOS/CmuxNext --arg=CmuxNextAppTests.SidebarFoldKeyboardTests,CmuxNextAppTests.SidebarFoldAccessibilityTests --env CMUX_TEST_REQUIRE_GUI=1 on the fleet: red at 83c8d98ecdc (new test only: clickingAnotherFoldMovesFocusAndItsRingAway fails, focus and ring stay on Show more and Space toggles it); green at b4a7689370c and at the final head 3f6aa3302b9f382803aec1a5851cd3831d9bce0a (after merging base for the conflict and base's CloudAppLinkOwnerAnswerTests compile fix): SidebarFoldKeyboardTests 5/5, SidebarFoldAccessibilityTests 3/3.
A click on a tab row (or any row but a group header or disclosure: section, empty section, empty group, folder, block, status) takes keyboard focus and its ring off a focused disclosure or header, as workspace and item clicks already did, so Return, Space and the arrows can't act on the old disclosure. Red at 6e637c452b0 (new clickingATabRowTakesFocusOffTheFold: focus and ring stay on Show more after the tab click, and Return/Space toggle it); green at 30360ae080c4cf8433cc4f633188d058bbb053ff: SidebarFoldKeyboardTests 6/6, SidebarFoldAccessibilityTests 3/3.

Design spec

Fits sidebar.md (leo-workspace design/sidebar.md): the Done and Show more fold rows keep their look; they only join the keyboard walk and draw the sidebar's existing keyboard focus ring, as group headers already do. No spec change.

No capture: keyboard focus and activation behaviour only; the fold rows look the same except for the existing focus ring, and the tests above check the ring.

Changelog

Changed: Keyboard-only users can reach, focus and open or close Done and Show more sidebar disclosure rows.

risk: normal

Parent: #27671

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Summary by cubic

Makes the sidebar's Done and Show more disclosure rows navigable by keyboard and VoiceOver; they were previously click-only. Keyboard, accessibility, and mouse activation now use the same fold toggle action.

Up/Down, Tab, and Shift-Tab move focus to a disclosure; Return and Space toggle it; Left and Right close or open it; VoiceOver press does the same.
A mouse click moves focus to the clicked disclosure without a ring, so the next Space or Return acts on that row; the ring shows only when keyboard focus moved there.
A click anywhere but on a group header or disclosure clears fold focus, so Return or Space after it never toggles the fold the keyboard had focused.
Focus never changes workspace selection and clears when a disclosure disappears or its view is recycled; a hidden or stale accessibility element cannot toggle its fold.
Adds SidebarFoldKeyboardTests and SidebarFoldAccessibilityTests covering reachability, activation, open/close, selection preservation, and stale focus cleanup.