fix(sidebar): expose workspace close button to accessibility

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Summary

Fixes #15752.

The workspace-row close affordance was image-only in both sidebar implementations. The AppKit row had only a tooltip, and the SwiftUI fallback likewise had help text but no explicit accessibility name or identifier.

This change:

• gives the revealed workspace close control the existing localized close label;
• exposes a stable sidebarWorkspaceCloseButton accessibility identifier in both AppKit and SwiftUI;
• sets the AppKit control's accessibility role to .button;
• removes the concealed AppKit control from the accessibility tree, matching the existing SwiftUI hidden behavior;
• adds a regression test that walks a configured AppKit workspace row and verifies hidden → revealed → hidden accessibility state.

No visible UI or close behavior changes.

Testing

Added workspaceCloseButtonAccessibilityFollowsRevealState in SidebarAppKitRowCellTests. The regression test is committed before the fix, per repository guidance.

I could not run the macOS app-host test suite from this GitHub-only environment. The maintainer noted on #15752 that local app-host execution is not required and that CI will run it on the project Macs once the PR is opened.

Localization audited: no new user-facing strings were added. Both implementations reuse the existing localized sidebar.closeWorkspace.tooltip / pinned-workspace tooltip text.

Changelog

Fixed: Workspace sidebar close buttons now expose an accessible name and stable identifier when revealed.

Demo Video

No video: this is an accessibility-metadata-only change with no visual UI change.

Checklist

• Behavior changes have added or updated tests, or Testing says why not
• UI, settings, menu, schema, help-text or user-facing docs change: localization audited, and the result is stated above
• New or changed v2 socket method allowlisted for cmux ssh: not applicable
• iOS connectivity, auth, lifecycle, workspace action, terminal I/O or mobile RPC contract change: not applicable
• User-facing docs updated if needed: not needed; behavior is self-describing through AX metadata
• Reviewed with a subagent before merge; awaiting repository review/CI

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Summary by cubic

Fixes #15752 by making the workspace close button accessible in both AppKit and SwiftUI sidebar rows.

• Gives the revealed close control the existing localized close label and a stable sidebarWorkspaceCloseButton identifier.
• Removes the control from the accessibility tree while concealed; AppKit role set to .button.
• Adds regression tests covering hidden → revealed → hidden state and reset on cell reuse.

No visual UI changes.

^{Written for commit bae990f. Summary will update on new commits.}

Summary by CodeRabbit

• Accessibility
  • Workspace close buttons now have a clear accessibility label and identifier, and are exposed to assistive technologies only while visible on hover. The accessibility state is cleared when the button is hidden or its row is reused, including for pinned workspaces.

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• cmuxTests/SidebarAppKitRowCellTests.swift

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📝 Walkthrough

Walkthrough

The workspace close buttons now have accessibility labels and identifiers. In the AppKit row, the close button’s accessibility exposure follows its hover-reveal state. Tests check accessibility and visibility before, during, and after hover, including after cell reuse.

Changes

Workspace close button accessibility

Layer / File(s)	Summary
Set close button accessibility metadata Sources/Sidebar/AppKitList/Cells/SidebarWorkspaceRowCellView.swift, Sources/Sidebar/SidebarWorkspaceTrailingStatusSlot.swift	The close buttons receive stable identifiers and accessibility labels. The AppKit button also receives a button role and starts excluded from the accessibility tree.
Synchronize accessibility with reveal state Sources/Sidebar/AppKitList/Cells/SidebarWorkspaceRowCellView.swift, cmuxTests/SidebarAppKitRowCellTests.swift	The AppKit button’s accessibility status resets on reuse and follows its reveal state. Tests check hidden and revealed states, including after cell reuse.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: austinywang

Merge Risk: ⚪ Minimal · up to bae99

The close controls expose their labels and identifiers, and the AppKit control is removed from accessibility when hidden or reused. No material merge-blocking risk is evident.

🚥 Pre-merge checks | ✅ 24 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 12.50% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (24 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise, specific, and accurately describes the primary accessibility change to the sidebar workspace close button.
Description check	✅ Passed	The description follows the required structure and clearly documents the problem, behavior change, testing added, test limitations, localization review, changelog entry, and demo-video rationale. The …
Linked Issues check	✅ Passed	The pull request satisfies the coding requirements in issue #15752. The AppKit and SwiftUI close controls expose the existing localized close text and the stable sidebarWorkspaceCloseButton identifi…
Out of Scope Changes check	✅ Passed	The changes are limited to the AppKit workspace-row close control, the SwiftUI workspace trailing close control, and focused AppKit accessibility tests. These changes directly implement issue #15752. …
Cmux Cloud Persistent Session And Early Input	✅ Passed	PASS: The pull request changes only workspace-row accessibility metadata and regression tests in three sidebar files. The diff does not create Cloud terminals, cmux-tui clients, transports, PTY readin…
Cmux Swift Actor Isolation	✅ Passed	PASS: The production changes only add accessibility metadata and reveal-state updates. SidebarWorkspaceRowTableCellView is already explicitly @MainActor, and its changed AppKit calls remain within…
Cmux Swift Blocking Runtime	✅ Passed	The production Swift changes only update accessibility metadata and reveal-state flags. The diff adds no semaphores, waits, sleeps, delayed dispatch, polling, synchronous dispatch, or locks. The test …
Cmux Browser Automation Off-Main	✅ Passed	PASS: The PR changes only sidebar accessibility code and sidebar tests. The authoritative diff contains no changes to browser socket automation, processV2Command, socketWorkerMethods, WebKit waits…
Cmux Expensive Synchronous Load	✅ Passed	The production diff only adds accessibility identifiers, labels, roles, and reveal-state updates in the workspace close controls. It adds no agent-history loader, transcript or JSON/JSONL parsing, dir…
Cmux Cache Substitution Correctness	✅ Passed	PASS. The production diff only adds accessibility metadata and reveal-state handling for the AppKit and SwiftUI close controls, plus tests. It does not replace a fresh authoritative read with a cached…
Cmux No Hacky Sleeps	✅ Passed	PASS. The pull request changes only three Swift files. The rule applies to TypeScript, JavaScript, shell, and non-Swift build/runtime scripts. The diff adds no covered delay, timer, polling, or sleep …
Cmux Algorithmic Complexity	✅ Passed	PASS. The production diff only sets accessibility metadata and reveal state on existing AppKit and SwiftUI controls. It adds no scalable-collection scan, sort, filter, join, batch rescan, or slower al…
Cmux Swift Concurrency	✅ Passed	The pull-request diff adds only accessibility metadata, reveal-state updates, and XCTest assertions. The added lines contain no DispatchQueue/DispatchGroup, new Combine, completion-handler API, or fir…
Cmux Swift @Concurrent	✅ Passed	The PR adds no @concurrent, nonisolated, async, await, Task, or heavy async call sites. The changed AppKit methods remain synchronous and the row class remains @MainActor; the SwiftUI view…
Cmux Swift Package Boundaries	✅ Passed	The production diff only changes AppKit and SwiftUI sidebar UI metadata and reveal-state handling. It adds accessibility role, label, identifier, and hidden-state updates to `SidebarWorkspaceRowTableC…
Cmux Swiftpm Lockfiles	✅ Passed	PASS. The reviewed range changes only three Swift source/test files. It contains no Package.swift, Package.resolved, .gitignore, workflow, or Xcode project/workspace package-reference changes. Therefo…
Cmux Swift Logging	✅ Passed	The pull request adds only accessibility metadata and state handling in production Swift, plus tests. The added lines contain no print, debugPrint, dump, NSLog, ad hoc logging, Logger, or se…
Cmux User-Facing Error Privacy	✅ Passed	The changed production code adds accessibility metadata for the workspace close control. It does not add or change a user-facing error, alert, command output, API error body, or recovery message. The …
Cmux Full Internationalization	✅ Passed	The production changes reuse existing localized tooltip values. AppKit uses String(localized:defaultValue:) for both close-label variants, and SwiftUI passes the already localized `closeButtonToolti…
Cmux Swiftui State Layout	✅ Passed	The SwiftUI diff only adds .accessibilityLabel and .accessibilityIdentifier to SidebarWorkspaceTrailingStatusSlot. The view uses immutable let inputs and a closure, with no new observation sta…
Cmux Architecture Rethink	✅ Passed	PASS — The PR is a small accessibility correctness fix. AppKit accessibility state is derived from the existing showsCloseNow transition in updateCloseVisibility(), with an explicit reset in `prep…
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	PASS. The diff changes sidebar row accessibility metadata in SidebarWorkspaceRowTableCellView and SidebarWorkspaceTrailingStatusSlot, plus tests. It does not add or materially change a user-visibl…
Cmux Source Artifacts	✅ Passed	The pull request changes only three hand-written Swift source/test files: two sidebar implementation files and cmuxTests/SidebarAppKitRowCellTests.swift. The diff adds accessibility behavior and reg…
Cmux No Test Or Debug Seam In Production Source	✅ Passed	PASS. The production diff only adds accessibility metadata and reveal-state updates for the workspace close control. It adds no test/debug member, test-build guard, visibility widening, or wrapper acc…

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at @cmuxTests/SidebarAppKitRowCellTests.swift:
- Around line 254-289: Update recycledHoveredCellSnapsCloseButtonHidden to
verify accessibility state across reuse: capture the close button while the cell
is hovered, assert it is an accessibility element, then call prepareForReuse()
and assert it is no longer one. Keep the existing visual-state assertions.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository: manaflow-ai/cmux/.coderabbit.yaml

Review profile: ASSERTIVE

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Run ID: d4242a56-0983-4deb-a42b-046f1eaf2631

📥 Commits

Reviewing files that changed from the base of the PR and between 61128c6 and 4b96ea2.

📒 Files selected for processing (3)

• Sources/Sidebar/AppKitList/Cells/SidebarWorkspaceRowCellView.swift
• Sources/Sidebar/SidebarWorkspaceTrailingStatusSlot.swift
• cmuxTests/SidebarAppKitRowCellTests.swift

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I have read the CLA Document v2.2 and I hereby sign the CLA

[teamleaderleo]

Review: adversarial pass on bae990f84f3a

Verdict: LAND with nits. It sets accessibility on the real control rather than a container, and the test asserts runtime state rather than source shape.

closeButton is a SidebarHeaderGlyphButton, declared final class SidebarHeaderGlyphButton: NSButton, so the test's as? NSButton cast resolves. Because the button is imagePosition = .imageOnly with no title it had no accessible name at all before, so setAccessibilityLabel is a genuine fix. setAccessibilityRole(.button) is redundant on an NSButton but harmless.

The test checks isAccessibilityElement(), accessibilityRole(), accessibilityLabel() and accessibilityIdentifier() on the live view after configure, enforcePointerHovering and prepareForReuse. No source grepping and no assertion on a string constant standing in for behaviour, so it satisfies the runtime-behaviour rule. Both the new test and the amended recycledHoveredCellSnapsCloseButtonHidden fail on main, because no descendant there carries identifier sidebarWorkspaceCloseButton and #require returns nil. Each of the four AppKit hunks is individually pinned.

The fix largely does not achieve its stated goal

updateCloseVisibility gates accessibility on showsCloseNow, which is isPointerHovering && !contextMenuVisible && model.canCloseWorkspace && !(model.showsShortcutHints || model.settings.alwaysShowShortcutHints).

So the close button becomes an accessibility element only while the pointer hovers the row. A VoiceOver or keyboard-only user who never hovers still cannot reach it, and with alwaysShowShortcutHints enabled it is never exposed at all. That is consistent with the pre-existing SwiftUI .accessibilityHidden(!showsCloseButton) behaviour, so it is not a regression, but the title oversells what lands. Either narrow the title or make exposure unconditional.

An em dash now reaches spoken copy

The pinned branch feeds "Pinned workspace — protected from Close" into setAccessibilityLabel. The string is pre-existing and sits on a context line, so an added-line scan comes back clean, but this PR promotes it from a tooltip into VoiceOver-spoken copy, which is user-facing text under the no-em-dash rule. The test only asserts the non-pinned sidebar.closeWorkspace.tooltip label, so the pinned branch is untested as well. Both are worth fixing in the same line.

Smaller

setAccessibilityElement(false) on a view that is already isHidden = true is largely redundant, since AppKit excludes hidden views from the accessibility tree. So part of what the test asserts may not change observable VoiceOver behaviour.

The SidebarWorkspaceTrailingStatusSlot.swift SwiftUI hunk has no test.

Verification

AppKit and SwiftUI were read, not compiled: there is no macOS here and I attempted no app build. The hunk-pinning claims are static reasoning about which assertion would fail. The em dash was confirmed with a detector I verified first (printf 'a\xe2\x80\x94b' | grep -cP '\x{2014}' prints 1).

— Raindrop g2 🫧 / Run: run_worker_20260930_3fc64ba6

[github-actions]

Merge receipt for bae990f84f: every check was green at merge (17 verified; 20 skipped by policy). Full suite runs on main after merge.