swiftui-platform-rules

name: swiftui-platform-rules description: macOS and iOS platform conventions plus XCUITest reliability rules. Covers menu bar ordering, window chrome (traffic lights, corner radius, minimum size), toolbar placements, sidebar width, Settings scene, dock/notifications, standard keyboard shortcuts (Cmd+N/O/S/W/Q/Z/F/,/M), iOS tab bar and safe areas, gestures, and XCUITest patterns (three-layer animation suppression, .firstMatch required, coordinate taps for non-hittable elements, single-launch test design, dragUp scroll helper, no Section-level accessibilityIdentifier). Invoke when writing or reviewing macOS window/menu/toolbar/settings code, platform-convention questions, iOS surfaces, or XCUITest tests in HarnessMonitorUITests.

Platform conventions and UI test reliability

Native platform conventions for macOS (current) and iOS (aspirational) plus XCUITest patterns that keep the test suite fast and reliable.

macOS platform rules

Menu bar

• Required menus in order: App menu, File, Edit, View, Window, Help.
• App menu: About, Settings (Cmd+,), Hide (Cmd+H), Hide Others (Cmd+Opt+H), Quit (Cmd+Q).
• Edit menu: Undo (Cmd+Z), Redo (Cmd+Shift+Z), Cut (Cmd+X), Copy (Cmd+C), Paste (Cmd+V), Select All (Cmd+A).
• Disabled menu items are grayed out, never hidden. Hiding breaks muscle memory.
• Keyboard shortcut hints right-aligned in menu items.
• Ellipsis (...) on menu items that open a dialog. No ellipsis for immediate actions.
• Custom menus go between View and Window.
• Every action in the UI must be accessible via the menu bar.

Windows

• Standard traffic light buttons always top-left. Never hide or replace.
• Red close button closes the window, not the app (unless single-window).
• Cmd+W closes window. Cmd+Q quits.
• Set sensible minimum window size (400x300pt floor). Use .windowResizability(.contentMinSize).
• Restore window position and size on next launch.
• New windows cascade (offset 22pt down and right from previous).
• Full screen support (Ctrl+Cmd+F or green button) for document-based and media apps.
• Window corner radius: 10pt (system standard).

Window chrome measurements

Toolbar

• SF Symbols at 13pt/regular weight. Icon + optional label.
• Standard placements: .principal (center), .navigation (leading), .primaryAction (trailing).
• Right-click > "Customize Toolbar" should work unless there's a reason not to.
• Separator: Divider() between toolbar item groups.

Sidebar

• Width: 200-280pt default, user-resizable.
• Minimum: 200pt. Collapses entirely below minimum.
• Sidebar items: SF Symbol icon + label, 28-32pt row height.
• Toggle with keyboard shortcut.
• On macOS 26: sidebar gets automatic Liquid Glass. Don't override with opaque backgrounds.

Settings window

• Opens with Cmd+, (always). Use Settings scene in SwiftUI.
• Tab-based with SF Symbol icons (General, Appearance, etc.).
• Fixed window size, non-resizable. Standard width: 500-650pt.
• Settings apply immediately. No Save/Apply/OK button.
• General tab first, Advanced last.
• "Restore Defaults" with confirmation where appropriate.

Hover and mouse

• Hover states on all interactive elements: subtle background (5-10% opacity accent).
• Cursor changes: pointer for clickable, I-beam for text, resize for edges.
• Tooltips after 500ms hover on non-obvious controls.
• Right-click context menus on all selectable elements.

Dock

• Badge count for pending items.
• Right-click dock menu: recent items, quick actions.
• Progress indication on dock icon for long operations.
• Dock bounce only for events needing immediate attention.

Notifications

• Use UNUserNotificationCenter.
• Default to banner (auto-dismiss ~5 seconds). Alert only for genuinely urgent information.
• Don't spam. Respect notification settings.
• Up to 4 actions in expanded notification.

Drag and drop (platform conventions)

• Support drag and drop between windows and apps where it makes sense.
• Visual feedback: lift with shadow (1.05x scale), reduce source opacity (0.5).
• Drop target: background color change or dashed border.
• Cancel: Escape key returns to source with spring animation.
• Minimum drop zone: 32x32pt.

For SwiftUI .draggable / .dropDestination API rules, see the swiftui-api-patterns skill.

Standard keyboard shortcuts

These shortcuts must work in any macOS app:

iOS platform rules

These rules apply to current and future iOS apps in this repository. The Harness Monitor app is macOS-only today, so these are aspirational reference for any future iOS target.

Safe areas

• Always respect safe areas. Interactive controls must remain within safe areas.
• Use .ignoresSafeArea() only for background content (images, maps, gradients).
• Bottom safe area: 34pt on Face ID devices. Don't place interactive controls within 34pt of the bottom edge.
• Status bar always visible unless in immersive content (video, photos).

Tab bar

• Bottom of screen, always visible during in-tab navigation.
• 2-5 tabs maximum. More than 5 uses a "More" tab.
• Icon + short label for each. Filled for selected, outline for unselected.
• Active tab: accent color tint. Inactive: gray.
• Tab bar height: 49pt (83pt with home indicator on Face ID devices).
• Each tab maintains independent navigation state.

Navigation bar

• Large title for top-level screens (.navigationBarTitleDisplayMode(.large)), inline for drill-down.
• Back button: system chevron + previous screen title. Never hide or replace.
• Trailing side: 1-2 action buttons maximum.
• Leading side: back button only (or close for modal presentations).
• Search: .searchable() modifier.

Gestures

• Swipe from left edge navigates back. Never override this system gesture.
• Swipe actions on list rows: trailing for destructive (red), leading for positive actions.
• Full swipe triggers the first action (delete, archive).
• Maximum 3 swipe actions per side.
• Long press for context menus on selectable content.
• Pull-to-refresh: .refreshable() modifier for refreshable content.
• Shake to undo is a system behavior. Don't disable it.

Touch targets

• 44x44pt minimum touch target. No exceptions.
• If the visual element is smaller, expand the hit area.
• Haptic feedback for significant interactions.
• No hover states - design for touch-first.

Scroll behavior

• Large titles collapse on scroll (automatic with NavigationStack).
• Scroll-to-top: tapping the status bar scrolls to top. Don't interfere.
• Rubber-banding at scroll limits. Never disable.
• System manages content insets for safe areas, bars, and keyboard. Don't manually set unless custom layout.

Launch (iOS)

• Cold launch to content: under 400ms target. Absolute max 3 seconds before watchdog kills the app.
• Launch screen matches initial screen layout (same background, layout skeleton). No logos or splash art.
• Don't show onboarding or login on every launch. Once, then straight to content.
• Restore previous state: last tab, scroll position, selection.

Permissions (iOS)

• Never request all permissions at launch.
• Ask in context: request camera when user taps "Scan QR code".
• Explain before asking: "We need camera access to scan QR codes" then system prompt.
• If denied: inline message explaining how to enable in Settings, with direct link.
• Graceful degradation: feature unavailable but app still works.

XCUITest speed and reliability

Animation suppression in the test host

The app disables animations when HARNESS_MONITOR_UI_TESTS=1 via three layers:

• SwiftUI: .transaction { $0.disablesAnimations = true } on root views
• AppKit: NSAnimationContext.current.duration = 0
• NSWindow: .animationBehavior = .none on every window via didBecomeKeyNotification

Do not add animations that bypass these layers (e.g. CADisplayLink-driven animations) without also checking the UI test environment flag.

Always use .firstMatch

Every element query must end with .firstMatch. Without it, XCUITest resolves the entire accessibility hierarchy to verify uniqueness, adding seconds per query.

// correct
app.buttons["Clear Session Cache"].firstMatch

// wrong - full hierarchy scan
app.buttons["Clear Session Cache"]

Exception: app.staticTexts["Statistics"] without .firstMatch works for section headers because macOS SwiftUI exposes them differently and .firstMatch can miss them.

Prefer .exists over waitForExistence

Use .exists for elements already rendered. Only use waitForExistence(timeout:) when genuinely waiting for something to appear (window opening, async content loading). Keep timeouts as short as possible - 2-3 seconds for post-action waits, Self.uiTimeout only for app launch and window creation.

Coordinate-based taps for non-hittable elements

Elements inside custom layouts (WrapLayout, GlassEffectContainer) may exist in the accessibility tree but report isHittable = false. Use coordinate-based tapping via centerCoordinate(in:for:).

Escape key to dismiss dialogs

Use app.typeKey(.escape, modifierFlags: []) to dismiss confirmation dialogs instead of searching for and tapping the Cancel button. It avoids an extra hierarchy search.

No Section-level accessibilityIdentifier

On macOS, .accessibilityIdentifier on a SwiftUI Section propagates to all child elements, clobbering their individual identifiers. Put identifiers on the children, not the Section.

Sidebar item element types

macOS SwiftUI List sidebar items appear as .button, .cell, or .radioButton depending on the version. Use the button(in:title:) helper that searches all three types.

Single-launch test design

Prefer one test method that launches the app once and tests multiple related assertions sequentially. Each launch(mode:) call adds 8-10 seconds of overhead. Group related assertions (navigation, scrolling, button verification, confirmation dialogs) into a single test flow.

Scroll with dragUp

Use the dragUp(in:element:distanceRatio:) helper anchored on a visible element inside the scroll region. element.scroll(byDeltaX:deltaY:) often targets the wrong scroll view. The distanceRatio of 3.0 works well for scrolling past a full section.

XCUITest references

• Jesse Squires - Xcode UI Testing Reliability Tips - animation disabling, layer.speed acceleration, timeout management
• Antoine van der Lee - Disable Animations Using Transactions - .transaction modifier replacing deprecated .animation(nil)
• objc.io - Transactions and Animations - disablesAnimations only kills implicit animations, not explicit
• Fat Bob Man - Disable Transition Animations - withTransaction for instant sheet/navigation, scope isolation
• Alex Ilyenko - Waits in XCUITest - XCTWaiter, expectation types, explicit vs implicit waits
• Pol Piella - Configuring UI Tests with Launch Arguments - ProcessInfo.processInfo.arguments pattern

Research backing

Rationale for these rules lives under apps/harness-monitor/docs/research/:

• ux/01-apple-hig-principles.md - HIG principles for macOS and iOS
• xcuitest-speed.md - XCUITest reliability and speed investigation report