Restore modern Settings window chrome

[austinywang]

Summary

• Make the AppKit-owned SettingsWindowFactory establish the complete modern chrome contract at construction: full-size content, transparent hidden titlebar, no legacy separator, and unified-compact toolbar.
• Install AppKit standard toggleSidebar toolbar chrome explicitly instead of assuming NSHostingController.sceneBridgingOptions will synthesize it.
• Route the toolbar item and the existing Toggle Left Sidebar command through one shared request path into the SwiftUI NavigationSplitView state.

Root cause and architectural fix

PR #7783 correctly made AppKit the single lifecycle owner, but window chrome remained implicitly delegated to the hosted SwiftUI hierarchy. sceneBridgingOptions = [.toolbars, .title] forwards toolbar content explicitly declared by a hosted view; this Settings root declares navigation/search state but no toolbar content, so the AppKit factory returned a bare titled window.

The factory now owns the NSWindow chrome container and its standard AppKit toolbar, while SwiftUI continues to own navigation, sidebar visibility state, search, and Settings content. The invariant is established before makeSettingsWindow returns, independent of ordering or scene timing, without changing the synchronous construction, reuse/teardown, geometry, activation, or navigation-delivery guarantees from #7783/#7800.

Regression coverage

Two-commit red/green structure:

1. 12dc775c4 adds SettingsWindowChromeTests only. It fails against the old factory because .fullSizeContentView, unified/transparent titlebar properties, and the toolbar are absent.
2. 2a9733c2b implements the factory-owned chrome invariant.

The test asserts the constructed NSWindow contract, the standard sidebar toolbar item and target/action, and end-to-end delivery through the same sidebar-toggle notification used by the menu command. Pixel-level rendering of AppKit/SwiftUI chrome is not faked in unit coverage and remains a dogfood check.

Related issue #5071

This covers #5071s visible legacy-chrome complaint in the current architecture: the older SwiftUI Window path discussed there was removed by #7783, and the AppKit factory fixed here is now the only Settings construction path. This PR intentionally does not restore or modify the removed SwiftUI scene lifecycle.

Validation

• scripts/check-pbxproj.sh
• scripts/lint-pbxproj-test-wiring.sh
• python3 scripts/check-package-resolved-policy.py
• python3 scripts/check-workspace-package-groups.py --check
• git diff --check
• No local xcodebuild or XCUITest run, per issue task; app-target compilation and tests are delegated to CI.
• python3 scripts/swift_file_length_budget.py was run. It reports nine pre-existing unrelated files over their checked-in budgets; this PR does not touch either budget TSV, and all touched Swift files remain below 500 lines.

Localization audit

No user-facing strings were added or changed. The toolbar uses AppKits standard NSToolbarItem.Identifier.toggleSidebar, including its system-localized label and accessibility description; the window title continues to use the existing localized settings.title key. No shortcuts, menus, schema text, docs, or locale catalogs changed.

Fixes #8010

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Summary by cubic

Restores modern Settings window chrome with full-size content, a transparent hidden titlebar, and an AppKit-owned unified-compact toolbar. Adds a standard sidebar toggle with routing that persists even when AppKit recreates the item; fixes #8010.

• Bug Fixes
  • SettingsWindowFactory now builds chrome at construction: .fullSizeContentView, transparent/hidden titlebar, no separator, and .unifiedCompact toolbar. Bridges only .title. Creates an NSToolbar (identifier cmux.settings.toolbar) with .iconOnly display, no customization/autosave, inserts .toggleSidebar, and assigns it to the window.
  • SettingsHostWindow owns the toolbar contract: NSToolbarDelegate limits allowed/default items to .toggleSidebar, implements toggleSidebar: to call SettingsWindowPresenter.requestSidebarToggle(), and uses toolbarWillAddItem to configure every inserted standard item so target/action stay correct when AppKit recreates it. Added SettingsWindowChromeTests.

^{Written for commit 1d68eef. Summary will update on new commits.}

Summary by CodeRabbit

• New Features

  • Settings windows now use a unified, modern toolbar and title bar appearance.
  • Added a sidebar toggle control to the settings toolbar.
  • Sidebar visibility can be toggled directly from the toolbar.

• Bug Fixes

  • Improved toolbar configuration and sidebar toggle action routing for more reliable settings navigation.

• Tests

  • Added coverage verifying settings window appearance, toolbar configuration, and sidebar toggle behavior.

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Project	Deployment	Actions	Updated (UTC)
cmux	Ready	Preview, Comment	Jul 14, 2026 12:56am
cmux-staging	Building	Preview, Comment	Jul 14, 2026 12:56am

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Review details

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: 50c37735-fa9a-4c43-9c1f-43b3fd4b4e16

📥 Commits

Reviewing files that changed from the base of the PR and between d93011b and 1d68eef.

📒 Files selected for processing (2)

• Sources/App/SettingsWindowFactory.swift
• cmuxTests/SettingsWindowChromeTests.swift

📝 Walkthrough

Walkthrough

The Settings window now uses explicit AppKit unified chrome, including a transparent full-size titlebar and sidebar toolbar toggle. Toolbar actions route through SettingsWindowPresenter, with new tests covering styling, delegation, and action delivery.

Changes

Settings window chrome

Layer / File(s)	Summary
Unified chrome configuration Sources/App/SettingsWindowFactory.swift	Configures full-size content, titlebar appearance, toolbar identifiers, and the sidebar toggle item explicitly.
Sidebar toggle routing Sources/App/SettingsWindowFactory.swift	Adds toolbar delegation and forwards the toggle action to SettingsWindowPresenter.requestSidebarToggle().
Chrome validation and test wiring cmuxTests/SettingsWindowChromeTests.swift, cmuxTests/SettingsWindowNavigationRoutingTests.swift, cmux.xcodeproj/project.pbxproj	Adds serialized assertions for window and toolbar configuration, exposes the toggle recorder, and registers the new test source in the project.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• manaflow-ai/cmux#7783: Established the AppKit-owned Settings window lifecycle and related sidebar-toggle pathway.
• manaflow-ai/cmux#7800: Also updates the Settings window factory and host wiring.

🚥 Pre-merge checks | ✅ 25

✅ Passed checks (25 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the main change: restoring the modern Settings window chrome.
Description check	✅ Passed	The description is detailed and covers summary, rationale, regression tests, validation, and related issues, with only optional template sections omitted.
Linked Issues check	✅ Passed	The changes restore full-size content, unified toolbar chrome, and a working sidebar toggle as required by #8010.
Out of Scope Changes check	✅ Passed	The added test, project wiring, and visibility tweak support the chrome fix and stay within the PR scope.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Cmux Swift Actor Isolation	✅ Passed	Only main-actor UI code changed; no new Sendable/shared-mutable/background-access isolation mistakes were introduced.
Cmux Swift Blocking Runtime	✅ Passed	PASS: No new blocking waits or locks appear in production Swift; only test-only Task.yield/Timer scaffolding is added under DEBUG tests.
Cmux Browser Automation Off-Main	✅ Passed	Diff only touches Settings window chrome and tests; no browser.* socket commands, routing, WebKit/AppKit worker-lane changes, or policy-test gaps were introduced.
Cmux Expensive Synchronous Load	✅ Passed	Diff only changes Settings window chrome and tests; no new RestorableAgentSessionIndex.load, JSON/JSONL parsing, or other heavy sync agent-history load on the main actor.
Cmux Cache Substitution Correctness	✅ Passed	Diff only changes Settings window chrome/toolbar wiring; no persistence, history, undo, snapshot, or cache substitution path is touched.
Cmux No Hacky Sleeps	✅ Passed	Changed files are Swift/test-only and add no fixed sleeps, timers-as-workarounds, asyncAfter, or polling.
Cmux Algorithmic Complexity	✅ Passed	PASS: The only new scan is toolbar.items.first(where:) over a one-item, AppKit-owned toolbar; the rest is fixed-size chrome setup and test scaffolding.
Cmux Swift Concurrency	✅ Passed	No new DispatchQueue/Combine/completion-handler/fire-and-forget Task patterns were added; the changed code stays synchronous and AppKit/XCTest callback-boundaries are allowed.
Cmux Swift @Concurrent	✅ Passed	No diff introduces @concurrent, nonisolated async, or UI-isolated heavy async work; added code is synchronous/MainActor-bound and existing async helpers are unchanged.
Cmux Swift File And Package Boundaries	✅ Passed	SettingsWindowFactory stays small (170 lines) and the change is focused AppKit/UI glue; added coverage is in tests, with no package-boundary breach.
Cmux Swiftpm Lockfiles	✅ Passed	The PR only wires a new test file into project.pbxproj; it has no SwiftPM package-reference, .gitignore, workflow, or Package.resolved changes, so the lockfile rule isn’t violated.
Cmux Swift Logging	✅ Passed	The PR diff adds no print/debugPrint/dump/NSLog/stdout logging; the existing Logger/fault call in SettingsWindowFactory is unchanged.
Cmux User-Facing Error Privacy	✅ Passed	PASS: Diff only adds AppKit chrome/toolbar wiring and a test; no new user-facing errors, alerts, command output, or recovery copy expose implementation details.
Cmux Full Internationalization	✅ Passed	No new user-facing text was introduced; the string keys were preexisting and already backed by translated xcstrings, and the rest is tests/comments/config identifiers.
Cmux Swiftui State Layout	✅ Passed	Diff only adjusts AppKit-owned settings chrome and a test; no new ObservableObject/@published, GeometryReader, lazy-row, or render-time state mutation in SwiftUI.
Cmux Architecture Rethink	✅ Passed	Adds required AppKit toolbar bridging while keeping one shared sidebar-toggle request path and a single SwiftUI owner for visibility state; no timing workaround.
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	Settings already uses cmux.settings and is registered in cmuxAuxiliaryWindowIdentifiers; this PR only changes chrome/toolbar behavior, not close-shortcut ownership.
Cmux Source Artifacts	✅ Passed	All changed paths are hand-written source/config/test files; no logs, screenshots, caches, build output, or scratch/artifact dirs appear in the PR diff.
Cmux No Test Or Debug Seam In Production Source	✅ Passed	Sources/App/SettingsWindowFactory.swift adds only real AppKit chrome/toolbar behavior; no #if DEBUG or test/debug seam member was added to production source.
Cmux No Ambient Global State	✅ Passed	No new file-scope funcs/vars or singletons were added; the PR only adds a static let and private helpers on an existing factory type, with test-only visibility tweaks.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch issue-8010-settings-titlebar-chrome

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[greptile-apps]

Greptile Summary

This PR restores modern Settings window chrome under AppKit ownership. The main changes are:

• Adds full-size content, a transparent hidden title bar, and unified compact toolbar styling.
• Installs a delegate-backed standard sidebar toggle item.
• Routes toolbar and menu actions through one sidebar-toggle request path.
• Adds tests for the window chrome and live toolbar action.

Confidence Score: 5/5

This looks safe to merge.

• The toolbar now has an explicit delegate and allowed/default item contract.
• The live item is configured after attachment and routes through the shared action path.
• Tests cover item retention, target assignment, and notification delivery.
• No blocking issues remain in the changed code.

Important Files Changed

Filename	Overview
Sources/App/SettingsWindowFactory.swift	Defines the AppKit-owned window chrome, toolbar delegate contract, and shared sidebar-toggle route.
cmuxTests/SettingsWindowChromeTests.swift	Checks the constructed chrome and verifies the live toolbar item's target and action delivery.
cmuxTests/SettingsWindowNavigationRoutingTests.swift	Makes the test-target notification recorder reusable by the new chrome tests.
cmux.xcodeproj/project.pbxproj	Wires the new Settings window chrome tests into the test target.

_{Reviews (3): Last reviewed commit: "fix: preserve live Settings toolbar rout..." | Re-trigger Greptile}