Stop unrelated defaults writes and pane geometry changes from re-evaluating chrome-heavy views - #14058

Summary

Every UserDefaults write re-evaluated the window root (ContentView) and the vertical tabs sidebar. Every pane geometry change re-evaluated every view observing the workspace. testMinimalModeToggleDoesNotReevaluateChromeHeavyBodies catches both. Toggling minimal mode writes one defaults key, and on main that re-evaluates ContentView / WorkspaceContentView / VerticalTabsSidebar 1 / 2 / 1 times; the test expects 0 / 0 / 0. With this change the test passes. Its _printChanges output on main (run 35903570794, ccdbf30):

ContentView: _titlebarLeftControlsLeadingInset, _titlebarLeftControlsTopInset, _titlebarTrafficLightTabBarInset, _titlebarTrafficLightTitlebarLeadingInset, _selectedLeftSidebarProviderId changed.
WorkspaceContentView: @self changed.
VerticalTabsSidebar: _selection, _selectedExtensionSidebarProviderId, _titlebarLeftControlsLeadingInset, _titlebarLeftControlsTopInset changed.
WorkspaceContentView: _workspace changed.

Dotted @AppStorage keys. A view that reads an @AppStorage property whose key contains a . re-evaluates its body on every write to the defaults suite. A view with a flat key re-evaluates only when its own key changes. The standalone experiment in #13930 shows this. Apart from _selection, a binding that ContentView passes down, every property in the ContentView and VerticalTabsSidebar lines above reads one of five dotted keys: four titlebarDebug.* insets and cmuxExtensionSidebar.providerId.

This PR renames them to flat keys (titlebarDebugLeftControlsLeadingInset, …, cmuxExtensionSidebarProviderId). At launch, values saved under the old keys move to the new ones. A value already stored under a new key wins, and the old keys are removed. Nothing else in the repository reads the old keys.

Workspace.tmuxLayoutSnapshot was @Published (since 656786f). No view body reads it. The window pane overlay reads it from event handlers, including the .workspacePaneGeometryDidChange notification that the geometry callback posts right after assigning it. Publishing it fired objectWillChange on every geometry change, including divider drags, so every view observing the workspace re-evaluated. paneLayoutVersion is gated so that divider drags do not do this. The snapshot is now a plain stored property.

The two causes are independent. Each change removes only its own _printChanges lines, and the test passes only with both. These runs used macOS 26; counts are ContentView / WorkspaceContentView / VerticalTabsSidebar.

The test already failed in the PR that added it: run 28413864324 of #7076 logged 6 / 8 / 10. Until #12053, the app-host shard classifier checked only XCTest summaries, so Swift Testing failures did not fail the shard.

Downgrade: the migration removes the old keys. An older build run afterwards shows the default sidebar view and the default titlebar insets.

Not changed here: more than 30 other @AppStorage keys still contain dots, including user settings such as terminal.textBoxMaxLines, fileExplorer.style and sessionIndex.compactView. Views that read them still re-evaluate on every defaults write. This PR does not include the repo-wide audit that #13930 suggests.

Fixes #13930. Refs #13879. This covers one of the five tests that #14006 lists as not covered.

Testing

Nothing was built or run locally. Hosted runs:

The E2E workflow ends red on every run. Its cleanup step exits 1 after the tests with "refusing to inspect app hosts outside runner temp". The results above come from the test log.

New tests: WindowDragHandleHitTests.testTitlebarChromeSettingsMigrateDottedKeysFromBeforeIssue13930 and SidebarProviderMenuRegressionTests.legacyDottedSelectionKeyMigratesToFlatKey() cover the migration. They include the case where a newer value wins over a leftover legacy value.

Localization audit: no user-facing strings changed. The renamed keys are UserDefaults storage keys.

Checklist

• I tested the change locally (hosted runs only, above)
• I added or updated tests for behavior changes
• For iOS connectivity, auth, lifecycle, workspace or terminal changes, I updated the deterministic soak coverage or explained why existing coverage still applies, and recorded the affected workload result (n/a: macOS app only)
• I updated docs/changelog if needed (none needed)
• I requested bot reviews after my latest commit (copy/paste block above or equivalent)
• All code review bot comments are resolved
• All human review comments are resolved

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Preserved existing sidebar selections and titlebar settings when updating the app, including cases where newer settings were already saved.
  • Improved responsiveness while dragging workspace dividers by reducing unnecessary screen updates.
  • Resolved a tracked failure affecting minimal-mode titlebar updates.