general: testability enhancements

.gitignore

@@ -1,4 +1,5 @@
 tasks
+python_impl
 AGENTS.md
 *.log
 *.app

Gaze/AppDelegate.swift

@@ -13,9 +13,8 @@ import SwiftUI
 class AppDelegate: NSObject, NSApplicationDelegate, ObservableObject {
     @Published var timerEngine: TimerEngine?
     private let settingsManager: SettingsManager = .shared
+    private let windowManager: WindowManaging
     private var updateManager: UpdateManager?
-    private var overlayReminderWindowController: NSWindowController?
-    private var subtleReminderWindowController: NSWindowController?
     private var cancellables = Set<AnyCancellable>()
     private var hasStartedTimers = false
 
@@ -24,6 +23,17 @@ class AppDelegate: NSObject, NSApplicationDelegate, ObservableObject {
     private var idleService: IdleMonitoringService?
     private var usageTrackingService: UsageTrackingService?
 
+    override init() {
+        self.windowManager = WindowManager.shared
+        super.init()
+    }
+    
+    /// Initializer for testing with injectable dependencies
+    init(windowManager: WindowManaging) {
+        self.windowManager = windowManager
+        super.init()
+    }
+
     func applicationDidFinishLaunching(_ notification: Notification) {
         // Set activation policy to hide dock icon
         NSApplication.shared.setActivationPolicy(.accessory)
@@ -146,7 +156,7 @@ class AppDelegate: NSObject, NSApplicationDelegate, ObservableObject {
         timerEngine?.$activeReminder
             .sink { [weak self] reminder in
                 guard let reminder = reminder else {
-                    self?.dismissOverlayReminder()
+                    self?.windowManager.dismissOverlayReminder()
                     return
                 }
                 self?.showReminder(reminder)
@@ -155,116 +165,41 @@ class AppDelegate: NSObject, NSApplicationDelegate, ObservableObject {
     }
 
     private func showReminder(_ event: ReminderEvent) {
-        let contentView: AnyView
-        let requiresFocus: Bool
-
         switch event {
         case .lookAwayTriggered(let countdownSeconds):
-            contentView = AnyView(
-                LookAwayReminderView(countdownSeconds: countdownSeconds) { [weak self] in
-                    self?.timerEngine?.dismissReminder()
-                }
-            )
-            requiresFocus = true
+            let view = LookAwayReminderView(countdownSeconds: countdownSeconds) { [weak self] in
+                self?.timerEngine?.dismissReminder()
+            }
+            windowManager.showReminderWindow(view, windowType: .overlay)
+            
         case .blinkTriggered:
             let sizePercentage = settingsManager.settings.subtleReminderSize.percentage
-            contentView = AnyView(
-                BlinkReminderView(sizePercentage: sizePercentage) { [weak self] in
-                    self?.timerEngine?.dismissReminder()
-                }
-            )
-            requiresFocus = false
+            let view = BlinkReminderView(sizePercentage: sizePercentage) { [weak self] in
+                self?.timerEngine?.dismissReminder()
+            }
+            windowManager.showReminderWindow(view, windowType: .subtle)
+            
         case .postureTriggered:
             let sizePercentage = settingsManager.settings.subtleReminderSize.percentage
-            contentView = AnyView(
-                PostureReminderView(sizePercentage: sizePercentage) { [weak self] in
-                    self?.timerEngine?.dismissReminder()
-                }
-            )
-            requiresFocus = false
+            let view = PostureReminderView(sizePercentage: sizePercentage) { [weak self] in
+                self?.timerEngine?.dismissReminder()
+            }
+            windowManager.showReminderWindow(view, windowType: .subtle)
+            
         case .userTimerTriggered(let timer):
             if timer.type == .overlay {
-                contentView = AnyView(
-                    UserTimerOverlayReminderView(timer: timer) { [weak self] in
-                        self?.timerEngine?.dismissReminder()
-                    }
-                )
-                requiresFocus = true
+                let view = UserTimerOverlayReminderView(timer: timer) { [weak self] in
+                    self?.timerEngine?.dismissReminder()
+                }
+                windowManager.showReminderWindow(view, windowType: .overlay)
             } else {
                 let sizePercentage = settingsManager.settings.subtleReminderSize.percentage
-                contentView = AnyView(
-                    UserTimerReminderView(timer: timer, sizePercentage: sizePercentage) {
-                        [weak self] in
-                        self?.timerEngine?.dismissReminder()
-                    }
-                )
-                requiresFocus = false
+                let view = UserTimerReminderView(timer: timer, sizePercentage: sizePercentage) { [weak self] in
+                    self?.timerEngine?.dismissReminder()
+                }
+                windowManager.showReminderWindow(view, windowType: .subtle)
             }
         }
-
-        showReminderWindow(contentView, requiresFocus: requiresFocus, isOverlay: requiresFocus)
-    }
-
-    private func showReminderWindow(_ content: AnyView, requiresFocus: Bool, isOverlay: Bool) {
-        guard let screen = NSScreen.main else { return }
-
-        let window: NSWindow
-        if requiresFocus {
-            window = KeyableWindow(
-                contentRect: screen.frame,
-                styleMask: [.borderless, .fullSizeContentView],
-                backing: .buffered,
-                defer: false
-            )
-        } else {
-            window = NonKeyWindow(
-                contentRect: screen.frame,
-                styleMask: [.borderless, .fullSizeContentView],
-                backing: .buffered,
-                defer: false
-            )
-        }
-
-        window.identifier = WindowIdentifiers.reminder
-        window.level = .floating
-        window.isOpaque = false
-        window.backgroundColor = .clear
-        window.contentView = NSHostingView(rootView: content)
-        window.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary]
-
-        // Allow mouse events only for overlay reminders (they need dismiss button)
-        // Subtle reminders should be completely transparent to mouse input
-        window.acceptsMouseMovedEvents = requiresFocus
-        window.ignoresMouseEvents = !requiresFocus
-
-        let windowController = NSWindowController(window: window)
-        windowController.showWindow(nil)
-
-        if requiresFocus {
-            window.makeKeyAndOrderFront(nil)
-            NSApp.activate(ignoringOtherApps: true)
-        } else {
-            window.orderFront(nil)
-        }
-
-        // Track overlay and subtle reminders separately
-        if isOverlay {
-            overlayReminderWindowController?.close()
-            overlayReminderWindowController = windowController
-        } else {
-            subtleReminderWindowController?.close()
-            subtleReminderWindowController = windowController
-        }
-    }
-
-    private func dismissOverlayReminder() {
-        overlayReminderWindowController?.close()
-        overlayReminderWindowController = nil
-    }
-
-    private func dismissSubtleReminder() {
-        subtleReminderWindowController?.close()
-        subtleReminderWindowController = nil
     }
 
     func openSettings(tab: Int = 0) {
@@ -272,8 +207,7 @@ class AppDelegate: NSObject, NSApplicationDelegate, ObservableObject {
 
         DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
             guard let self else { return }
-            SettingsWindowPresenter.shared.show(
-                settingsManager: self.settingsManager, initialTab: tab)
+            windowManager.showSettings(settingsManager: self.settingsManager, initialTab: tab)
         }
     }
 
@@ -282,33 +216,13 @@ class AppDelegate: NSObject, NSApplicationDelegate, ObservableObject {
 
         DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
             guard let self else { return }
-            OnboardingWindowPresenter.shared.show(settingsManager: self.settingsManager)
+            windowManager.showOnboarding(settingsManager: self.settingsManager)
         }
     }
 
     private func handleMenuDismissal() {
         NotificationCenter.default.post(name: Notification.Name("CloseMenuBarPopover"), object: nil)
-        dismissOverlayReminder()
+        windowManager.dismissOverlayReminder()
     }
 
 }
-
-class KeyableWindow: NSWindow {
-    override var canBecomeKey: Bool {
-        return true
-    }
-
-    override var canBecomeMain: Bool {
-        return true
-    }
-}
-
-class NonKeyWindow: NSWindow {
-    override var canBecomeKey: Bool {
-        return false
-    }
-
-    override var canBecomeMain: Bool {
-        return false
-    }
-}

Gaze/Constants/AccessibilityIdentifiers.swift

@@ -0,0 +1,73 @@
+//
+//  AccessibilityIdentifiers.swift
+//  Gaze
+//
+//  Centralized accessibility identifiers for UI testing.
+//
+
+import Foundation
+
+/// Centralized accessibility identifiers for UI elements.
+/// Use these in SwiftUI views with `.accessibilityIdentifier()` modifier.
+enum AccessibilityIdentifiers {
+    
+    // MARK: - Reminders
+    
+    enum Reminders {
+        static let lookAwayView = "reminder.lookAway"
+        static let blinkView = "reminder.blink"
+        static let postureView = "reminder.posture"
+        static let userTimerView = "reminder.userTimer"
+        static let userTimerOverlayView = "reminder.userTimerOverlay"
+        static let dismissButton = "reminder.dismissButton"
+        static let countdownLabel = "reminder.countdown"
+    }
+    
+    // MARK: - Menu Bar
+    
+    enum MenuBar {
+        static let contentView = "menuBar.content"
+        static let timerRow = "menuBar.timerRow"
+        static let pauseButton = "menuBar.pauseButton"
+        static let resumeButton = "menuBar.resumeButton"
+        static let skipButton = "menuBar.skipButton"
+        static let settingsButton = "menuBar.settingsButton"
+        static let quitButton = "menuBar.quitButton"
+    }
+    
+    // MARK: - Settings
+    
+    enum Settings {
+        static let window = "settings.window"
+        static let generalTab = "settings.tab.general"
+        static let timersTab = "settings.tab.timers"
+        static let smartModeTab = "settings.tab.smartMode"
+        static let aboutTab = "settings.tab.about"
+        
+        // Timer settings
+        static let lookAwayToggle = "settings.lookAway.toggle"
+        static let lookAwayInterval = "settings.lookAway.interval"
+        static let blinkToggle = "settings.blink.toggle"
+        static let blinkInterval = "settings.blink.interval"
+        static let postureToggle = "settings.posture.toggle"
+        static let postureInterval = "settings.posture.interval"
+        
+        // General settings
+        static let launchAtLoginToggle = "settings.launchAtLogin.toggle"
+        static let playSoundsToggle = "settings.playSounds.toggle"
+    }
+    
+    // MARK: - Onboarding
+    
+    enum Onboarding {
+        static let window = "onboarding.window"
+        static let welcomePage = "onboarding.page.welcome"
+        static let lookAwayPage = "onboarding.page.lookAway"
+        static let blinkPage = "onboarding.page.blink"
+        static let posturePage = "onboarding.page.posture"
+        static let generalPage = "onboarding.page.general"
+        static let completionPage = "onboarding.page.completion"
+        static let continueButton = "onboarding.button.continue"
+        static let backButton = "onboarding.button.back"
+    }
+}

Gaze/Protocols/TimeProviding.swift

@@ -0,0 +1,44 @@
+//
+//  TimeProviding.swift
+//  Gaze
+//
+//  Protocol for abstracting time sources to enable deterministic testing.
+//
+
+import Foundation
+
+/// Protocol for providing current time, enabling deterministic tests.
+protocol TimeProviding {
+    /// Returns the current date/time
+    func now() -> Date
+}
+
+/// Default implementation that uses the system clock
+struct SystemTimeProvider: TimeProviding {
+    func now() -> Date {
+        Date()
+    }
+}
+
+/// Test implementation that allows manual time control
+final class MockTimeProvider: TimeProviding {
+    private var currentTime: Date
+    
+    init(startTime: Date = Date()) {
+        self.currentTime = startTime
+    }
+    
+    func now() -> Date {
+        currentTime
+    }
+    
+    /// Advances time by the specified interval
+    func advance(by interval: TimeInterval) {
+        currentTime = currentTime.addingTimeInterval(interval)
+    }
+    
+    /// Sets the current time to a specific date
+    func setTime(_ date: Date) {
+        currentTime = date
+    }
+}

Gaze/Protocols/TimerEngineProviding.swift

@@ -0,0 +1,86 @@
+//
+//  TimerEngineProviding.swift
+//  Gaze
+//
+//  Protocol abstraction for TimerEngine to enable dependency injection and testing.
+//
+
+import Combine
+import Foundation
+
+/// Protocol that defines the interface for timer engine functionality.
+/// This abstraction allows for dependency injection and easy mocking in tests.
+@MainActor
+protocol TimerEngineProviding: AnyObject, ObservableObject {
+    /// Current timer states for all active timers
+    var timerStates: [TimerIdentifier: TimerState] { get }
+    
+    /// Publisher for timer states changes
+    var timerStatesPublisher: Published<[TimerIdentifier: TimerState]>.Publisher { get }
+    
+    /// Currently active reminder, if any
+    var activeReminder: ReminderEvent? { get set }
+    
+    /// Publisher for active reminder changes
+    var activeReminderPublisher: Published<ReminderEvent?>.Publisher { get }
+    
+    /// Starts all enabled timers
+    func start()
+    
+    /// Stops all timers
+    func stop()
+    
+    /// Pauses all timers
+    func pause()
+    
+    /// Resumes all timers
+    func resume()
+    
+    /// Pauses a specific timer
+    func pauseTimer(identifier: TimerIdentifier)
+    
+    /// Resumes a specific timer
+    func resumeTimer(identifier: TimerIdentifier)
+    
+    /// Skips the next reminder for a specific timer and resets it
+    func skipNext(identifier: TimerIdentifier)
+    
+    /// Dismisses the current active reminder
+    func dismissReminder()
+    
+    /// Triggers a reminder for a specific timer
+    func triggerReminder(for identifier: TimerIdentifier)
+    
+    /// Gets the time remaining for a specific timer
+    func getTimeRemaining(for identifier: TimerIdentifier) -> TimeInterval
+    
+    /// Gets a formatted string of time remaining for a specific timer
+    func getFormattedTimeRemaining(for identifier: TimerIdentifier) -> String
+    
+    /// Checks if a timer is currently paused
+    func isTimerPaused(_ identifier: TimerIdentifier) -> Bool
+    
+    /// Handles system sleep event
+    func handleSystemSleep()
+    
+    /// Handles system wake event
+    func handleSystemWake()
+    
+    /// Sets up smart mode with fullscreen and idle detection services
+    func setupSmartMode(
+        fullscreenService: FullscreenDetectionService?,
+        idleService: IdleMonitoringService?
+    )
+}
+
+// MARK: - TimerEngine conformance
+
+extension TimerEngine: TimerEngineProviding {
+    var timerStatesPublisher: Published<[TimerIdentifier: TimerState]>.Publisher {
+        $timerStates
+    }
+    
+    var activeReminderPublisher: Published<ReminderEvent?>.Publisher {
+        $activeReminder
+    }
+}

Gaze/Protocols/WindowManaging.swift

@@ -0,0 +1,51 @@
+//
+//  WindowManaging.swift
+//  Gaze
+//
+//  Protocol abstraction for window management to enable dependency injection and testing.
+//
+
+import AppKit
+import SwiftUI
+
+/// Represents the type of reminder window to display
+enum ReminderWindowType {
+    case overlay  // Full-screen, focus-stealing windows (lookAway, user timer overlays)
+    case subtle   // Non-intrusive windows (blink, posture, user timer subtle)
+}
+
+/// Protocol that defines the interface for window management.
+/// This abstraction allows for dependency injection and easy mocking in tests.
+@MainActor
+protocol WindowManaging: AnyObject {
+    /// Shows a reminder window with the given content
+    /// - Parameters:
+    ///   - content: The SwiftUI view to display
+    ///   - windowType: The type of reminder window
+    func showReminderWindow<Content: View>(_ content: Content, windowType: ReminderWindowType)
+    
+    /// Dismisses the overlay reminder window
+    func dismissOverlayReminder()
+    
+    /// Dismisses the subtle reminder window
+    func dismissSubtleReminder()
+    
+    /// Dismisses all reminder windows
+    func dismissAllReminders()
+    
+    /// Shows the settings window
+    /// - Parameters:
+    ///   - settingsManager: The settings manager to use
+    ///   - initialTab: The initial tab to display
+    func showSettings(settingsManager: any SettingsProviding, initialTab: Int)
+    
+    /// Shows the onboarding window
+    /// - Parameter settingsManager: The settings manager to use
+    func showOnboarding(settingsManager: any SettingsProviding)
+    
+    /// Whether an overlay reminder is currently visible
+    var isOverlayReminderVisible: Bool { get }
+    
+    /// Whether a subtle reminder is currently visible
+    var isSubtleReminderVisible: Bool { get }
+}

Gaze/Services/ServiceContainer.swift

@@ -5,6 +5,7 @@
 //  Dependency injection container for managing service instances.
 //
 
+import Combine
 import Foundation
 
 /// A simple dependency injection container for managing service instances.
@@ -45,7 +46,7 @@ final class ServiceContainer {
     
     /// Creates a test container with injectable dependencies
     /// - Parameters:
-    ///   - settingsManager: The settings manager to use (defaults to MockSettingsManager in tests)
+    ///   - settingsManager: The settings manager to use
     ///   - enforceModeService: The enforce mode service to use
     init(
         settingsManager: any SettingsProviding,
@@ -69,6 +70,11 @@ final class ServiceContainer {
         return engine
     }
     
+    /// Sets a custom timer engine (useful for testing)
+    func setTimerEngine(_ engine: TimerEngine) {
+        _timerEngine = engine
+    }
+    
     /// Sets up smart mode services
     func setupSmartModeServices() {
         let settings = settingsManager.settings
@@ -104,9 +110,57 @@ final class ServiceContainer {
         usageTrackingService = nil
     }
     
-    /// Creates a new container configured for testing
+    /// Creates a new container configured for testing with default mock settings
     static func forTesting(settings: AppSettings = .defaults) -> ServiceContainer {
-        // We need to create this at runtime in tests using MockSettingsManager
-        fatalError("Use init(settingsManager:) directly in tests")
+        let mockSettings = MockSettingsManager(settings: settings)
+        return ServiceContainer(settingsManager: mockSettings)
     }
 }
+
+/// A mock settings manager for use in ServiceContainer.forTesting()
+/// This is a minimal implementation - use the full MockSettingsManager from tests for more features
+@MainActor
+final class MockSettingsManager: ObservableObject, SettingsProviding {
+    @Published var settings: AppSettings
+    
+    var settingsPublisher: Published<AppSettings>.Publisher {
+        $settings
+    }
+    
+    private let timerConfigKeyPaths: [TimerType: WritableKeyPath<AppSettings, TimerConfiguration>] = [
+        .lookAway: \.lookAwayTimer,
+        .blink: \.blinkTimer,
+        .posture: \.postureTimer,
+    ]
+    
+    init(settings: AppSettings = .defaults) {
+        self.settings = settings
+    }
+    
+    func timerConfiguration(for type: TimerType) -> TimerConfiguration {
+        guard let keyPath = timerConfigKeyPaths[type] else {
+            preconditionFailure("Unknown timer type: \(type)")
+        }
+        return settings[keyPath: keyPath]
+    }
+    
+    func updateTimerConfiguration(for type: TimerType, configuration: TimerConfiguration) {
+        guard let keyPath = timerConfigKeyPaths[type] else {
+            preconditionFailure("Unknown timer type: \(type)")
+        }
+        settings[keyPath: keyPath] = configuration
+    }
+    
+    func allTimerConfigurations() -> [TimerType: TimerConfiguration] {
+        var configs: [TimerType: TimerConfiguration] = [:]
+        for (type, keyPath) in timerConfigKeyPaths {
+            configs[type] = settings[keyPath: keyPath]
+        }
+        return configs
+    }
+    
+    func save() {}
+    func saveImmediately() {}
+    func load() {}
+    func resetToDefaults() { settings = .defaults }
+}

Gaze/Services/TimerEngine.swift

@@ -17,6 +17,9 @@ class TimerEngine: ObservableObject {
     private let settingsProvider: any SettingsProviding
     private var sleepStartTime: Date?
     
+    /// Time provider for deterministic testing (defaults to system time)
+    private let timeProvider: TimeProviding
+    
     // For enforce mode integration
     private var enforceModeService: EnforceModeService?
     
@@ -25,9 +28,14 @@ class TimerEngine: ObservableObject {
     private var idleService: IdleMonitoringService?
     private var cancellables = Set<AnyCancellable>()
 
-    init(settingsManager: any SettingsProviding, enforceModeService: EnforceModeService? = nil) {
+    init(
+        settingsManager: any SettingsProviding,
+        enforceModeService: EnforceModeService? = nil,
+        timeProvider: TimeProviding = SystemTimeProvider()
+    ) {
         self.settingsProvider = settingsManager
         self.enforceModeService = enforceModeService ?? EnforceModeService.shared
+        self.timeProvider = timeProvider
         
         Task { @MainActor in
             self.enforceModeService?.setTimerEngine(self)
@@ -300,7 +308,7 @@ class TimerEngine: ObservableObject {
             guard !state.isPaused else { continue }
             guard state.isActive else { continue }
             
-            if state.targetDate < Date() - 3.0 {
+            if state.targetDate < timeProvider.now() - 3.0 {
                 skipNext(identifier: identifier)
                 continue
             }
@@ -365,7 +373,7 @@ class TimerEngine: ObservableObject {
     /// - Saves current time for elapsed calculation
     /// - Pauses all active timers
     func handleSystemSleep() {
-        sleepStartTime = Date()
+        sleepStartTime = timeProvider.now()
         for (id, var state) in timerStates {
             state.pauseReasons.insert(.system)
             state.isPaused = true
@@ -387,7 +395,7 @@ class TimerEngine: ObservableObject {
             sleepStartTime = nil
         }
         
-        let elapsedSeconds = Int(Date().timeIntervalSince(sleepStart))
+        let elapsedSeconds = Int(timeProvider.now().timeIntervalSince(sleepStart))
         
         guard elapsedSeconds >= 1 else {
             for (id, var state) in timerStates {

Gaze/Services/WindowManager.swift

@@ -0,0 +1,108 @@
+//
+//  WindowManager.swift
+//  Gaze
+//
+//  Concrete implementation of WindowManaging for production use.
+//
+
+import AppKit
+import SwiftUI
+
+/// Production implementation of WindowManaging that creates real AppKit windows.
+@MainActor
+final class WindowManager: WindowManaging {
+    static let shared = WindowManager()
+    
+    private var overlayReminderWindowController: NSWindowController?
+    private var subtleReminderWindowController: NSWindowController?
+    
+    var isOverlayReminderVisible: Bool {
+        overlayReminderWindowController?.window?.isVisible ?? false
+    }
+    
+    var isSubtleReminderVisible: Bool {
+        subtleReminderWindowController?.window?.isVisible ?? false
+    }
+    
+    private init() {}
+    
+    func showReminderWindow<Content: View>(_ content: Content, windowType: ReminderWindowType) {
+        guard let screen = NSScreen.main else { return }
+        
+        let requiresFocus = windowType == .overlay
+        let window: NSWindow
+        
+        if requiresFocus {
+            window = KeyableWindow(
+                contentRect: screen.frame,
+                styleMask: [.borderless, .fullSizeContentView],
+                backing: .buffered,
+                defer: false
+            )
+        } else {
+            window = NonKeyWindow(
+                contentRect: screen.frame,
+                styleMask: [.borderless, .fullSizeContentView],
+                backing: .buffered,
+                defer: false
+            )
+        }
+        
+        window.identifier = WindowIdentifiers.reminder
+        window.level = .floating
+        window.isOpaque = false
+        window.backgroundColor = .clear
+        window.contentView = NSHostingView(rootView: content)
+        window.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary]
+        window.acceptsMouseMovedEvents = requiresFocus
+        window.ignoresMouseEvents = !requiresFocus
+        
+        let windowController = NSWindowController(window: window)
+        windowController.showWindow(nil)
+        
+        if requiresFocus {
+            window.makeKeyAndOrderFront(nil)
+            NSApp.activate(ignoringOtherApps: true)
+        } else {
+            window.orderFront(nil)
+        }
+        
+        switch windowType {
+        case .overlay:
+            overlayReminderWindowController?.close()
+            overlayReminderWindowController = windowController
+        case .subtle:
+            subtleReminderWindowController?.close()
+            subtleReminderWindowController = windowController
+        }
+    }
+    
+    func dismissOverlayReminder() {
+        overlayReminderWindowController?.close()
+        overlayReminderWindowController = nil
+    }
+    
+    func dismissSubtleReminder() {
+        subtleReminderWindowController?.close()
+        subtleReminderWindowController = nil
+    }
+    
+    func dismissAllReminders() {
+        dismissOverlayReminder()
+        dismissSubtleReminder()
+    }
+    
+    func showSettings(settingsManager: any SettingsProviding, initialTab: Int) {
+        // Use the existing presenter for now
+        if let realSettings = settingsManager as? SettingsManager {
+            SettingsWindowPresenter.shared.show(settingsManager: realSettings, initialTab: initialTab)
+        }
+    }
+    
+    func showOnboarding(settingsManager: any SettingsProviding) {
+        // Use the existing presenter for now
+        if let realSettings = settingsManager as? SettingsManager {
+            OnboardingWindowPresenter.shared.show(settingsManager: realSettings)
+        }
+    }
+}

Gaze/Views/Reminders/BlinkReminderView.swift

@@ -46,6 +46,7 @@ struct BlinkReminderView: View {
         .opacity(opacity)
         .frame(maxWidth: .infinity, maxHeight: .infinity)
         .padding(.top, screenHeight * 0.05)
+        .accessibilityIdentifier(AccessibilityIdentifiers.Reminders.blinkView)
         .onAppear {
             startAnimation()
         }

Gaze/Views/Reminders/LookAwayReminderView.swift

@@ -64,6 +64,7 @@ struct LookAwayReminderView: View {
                         .font(.system(size: 48, weight: .bold))
                         .foregroundColor(.white)
                         .monospacedDigit()
+                        .accessibilityIdentifier(AccessibilityIdentifiers.Reminders.countdownLabel)
                 }
 
                 Text("Press ESC or Space to skip")
@@ -81,11 +82,13 @@ struct LookAwayReminderView: View {
                             .foregroundColor(.white.opacity(0.7))
                     }
                     .buttonStyle(.plain)
+                    .accessibilityIdentifier(AccessibilityIdentifiers.Reminders.dismissButton)
                     .padding(30)
                 }
                 Spacer()
             }
         }
+        .accessibilityIdentifier(AccessibilityIdentifiers.Reminders.lookAwayView)
         .onAppear {
             startCountdown()
             setupKeyMonitor()

Gaze/Views/Reminders/PostureReminderView.swift

@@ -28,6 +28,7 @@ struct PostureReminderView: View {
         .offset(y: yOffset)
         .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .top)
         .padding(.top, screenHeight * 0.075)
+        .accessibilityIdentifier(AccessibilityIdentifiers.Reminders.postureView)
         .onAppear {
             startAnimation()
         }

Gaze/Views/Setup/EnforceModeSetupView.swift

@@ -25,8 +25,8 @@ struct EnforceModeSetupView: View {
     @ObservedObject var calibrationManager = CalibrationManager.shared
 
     var body: some View {
-        VStack(spacing: 0) {
-            ScrollView {
+        ScrollView {
+            VStack(spacing: 0) {
                 VStack(spacing: 16) {
                     Image(systemName: "video.fill")
                         .font(.system(size: 60))
@@ -171,9 +171,12 @@ struct EnforceModeSetupView: View {
                         .foregroundColor(.secondary)
 
                     if calibrationManager.needsRecalibration() {
-                        Label("Calibration expired - recalibration recommended", systemImage: "exclamationmark.triangle.fill")
-                            .font(.caption)
-                            .foregroundColor(.orange)
+                        Label(
+                            "Calibration expired - recalibration recommended",
+                            systemImage: "exclamationmark.triangle.fill"
+                        )
+                        .font(.caption)
+                        .foregroundColor(.orange)
                     } else {
                         Label("Calibration active and valid", systemImage: "checkmark.circle.fill")
                             .font(.caption)
@@ -191,7 +194,9 @@ struct EnforceModeSetupView: View {
             }) {
                 HStack {
                     Image(systemName: "target")
-                    Text(calibrationManager.calibrationData.isComplete ? "Recalibrate" : "Run Calibration")
+                    Text(
+                        calibrationManager.calibrationData.isComplete
+                            ? "Recalibrate" : "Run Calibration")
                 }
                 .frame(maxWidth: .infinity)
                 .padding(.vertical, 8)
@@ -200,7 +205,9 @@ struct EnforceModeSetupView: View {
             .controlSize(.regular)
         }
         .padding()
-        .glassEffectIfAvailable(GlassStyle.regular.tint(.blue.opacity(0.1)), in: .rect(cornerRadius: 12))
+        .glassEffectIfAvailable(
+            GlassStyle.regular.tint(.blue.opacity(0.1)), in: .rect(cornerRadius: 12)
+        )
         .sheet(isPresented: $showCalibrationWindow) {
             EyeTrackingCalibrationView()
         }
@@ -427,8 +434,11 @@ struct EnforceModeSetupView: View {
                 Button(action: {
                     eyeTrackingService.enableDebugLogging.toggle()
                 }) {
-                    Image(systemName: eyeTrackingService.enableDebugLogging ? "ant.circle.fill" : "ant.circle")
-                        .foregroundColor(eyeTrackingService.enableDebugLogging ? .orange : .secondary)
+                    Image(
+                        systemName: eyeTrackingService.enableDebugLogging
+                            ? "ant.circle.fill" : "ant.circle"
+                    )
+                    .foregroundColor(eyeTrackingService.enableDebugLogging ? .orange : .secondary)
                 }
                 .buttonStyle(.plain)
                 .help("Toggle console debug logging")
@@ -450,31 +460,45 @@ struct EnforceModeSetupView: View {
                     .foregroundColor(.secondary)
 
                 if let leftRatio = eyeTrackingService.debugLeftPupilRatio,
-                   let rightRatio = eyeTrackingService.debugRightPupilRatio {
+                    let rightRatio = eyeTrackingService.debugRightPupilRatio
+                {
                     HStack(spacing: 16) {
                         VStack(alignment: .leading, spacing: 2) {
                             Text("Left Pupil: \(String(format: "%.3f", leftRatio))")
                                 .font(.caption2)
                                 .foregroundColor(
-                                    !trackingConstants.minPupilEnabled && !trackingConstants.maxPupilEnabled ? .secondary :
-                                    (leftRatio < trackingConstants.minPupilRatio || leftRatio > trackingConstants.maxPupilRatio) ? .orange : .green
+                                    !trackingConstants.minPupilEnabled
+                                        && !trackingConstants.maxPupilEnabled
+                                        ? .secondary
+                                        : (leftRatio < trackingConstants.minPupilRatio
+                                            || leftRatio > trackingConstants.maxPupilRatio)
+                                            ? .orange : .green
                                 )
                             Text("Right Pupil: \(String(format: "%.3f", rightRatio))")
                                 .font(.caption2)
                                 .foregroundColor(
-                                    !trackingConstants.minPupilEnabled && !trackingConstants.maxPupilEnabled ? .secondary :
-                                    (rightRatio < trackingConstants.minPupilRatio || rightRatio > trackingConstants.maxPupilRatio) ? .orange : .green
+                                    !trackingConstants.minPupilEnabled
+                                        && !trackingConstants.maxPupilEnabled
+                                        ? .secondary
+                                        : (rightRatio < trackingConstants.minPupilRatio
+                                            || rightRatio > trackingConstants.maxPupilRatio)
+                                            ? .orange : .green
                                 )
                         }
 
                         Spacer()
 
                         VStack(alignment: .trailing, spacing: 2) {
-                            Text("Range: \(String(format: "%.2f", trackingConstants.minPupilRatio)) - \(String(format: "%.2f", trackingConstants.maxPupilRatio))")
-                                .font(.caption2)
-                                .foregroundColor(.secondary)
-                            let bothEyesOut = (leftRatio < trackingConstants.minPupilRatio || leftRatio > trackingConstants.maxPupilRatio) && 
-                                             (rightRatio < trackingConstants.minPupilRatio || rightRatio > trackingConstants.maxPupilRatio)
+                            Text(
+                                "Range: \(String(format: "%.2f", trackingConstants.minPupilRatio)) - \(String(format: "%.2f", trackingConstants.maxPupilRatio))"
+                            )
+                            .font(.caption2)
+                            .foregroundColor(.secondary)
+                            let bothEyesOut =
+                                (leftRatio < trackingConstants.minPupilRatio
+                                    || leftRatio > trackingConstants.maxPupilRatio)
+                                && (rightRatio < trackingConstants.minPupilRatio
+                                    || rightRatio > trackingConstants.maxPupilRatio)
                             Text(bothEyesOut ? "Both Out ⚠️" : "In Range ✓")
                                 .font(.caption2)
                                 .foregroundColor(bothEyesOut ? .orange : .green)
@@ -487,32 +511,43 @@ struct EnforceModeSetupView: View {
                 }
 
                 if let yaw = eyeTrackingService.debugYaw,
-                   let pitch = eyeTrackingService.debugPitch {
+                    let pitch = eyeTrackingService.debugPitch
+                {
                     HStack(spacing: 16) {
                         VStack(alignment: .leading, spacing: 2) {
                             Text("Yaw: \(String(format: "%.3f", yaw))")
                                 .font(.caption2)
                                 .foregroundColor(
-                                    !trackingConstants.yawEnabled ? .secondary :
-                                    abs(yaw) > trackingConstants.yawThreshold ? .orange : .green
+                                    !trackingConstants.yawEnabled
+                                        ? .secondary
+                                        : abs(yaw) > trackingConstants.yawThreshold
+                                            ? .orange : .green
                                 )
                             Text("Pitch: \(String(format: "%.3f", pitch))")
                                 .font(.caption2)
                                 .foregroundColor(
-                                    !trackingConstants.pitchUpEnabled && !trackingConstants.pitchDownEnabled ? .secondary :
-                                    (pitch > trackingConstants.pitchUpThreshold || pitch < trackingConstants.pitchDownThreshold) ? .orange : .green
+                                    !trackingConstants.pitchUpEnabled
+                                        && !trackingConstants.pitchDownEnabled
+                                        ? .secondary
+                                        : (pitch > trackingConstants.pitchUpThreshold
+                                            || pitch < trackingConstants.pitchDownThreshold)
+                                            ? .orange : .green
                                 )
                         }
 
                         Spacer()
 
                         VStack(alignment: .trailing, spacing: 2) {
-                            Text("Yaw Max: \(String(format: "%.2f", trackingConstants.yawThreshold))")
-                                .font(.caption2)
-                                .foregroundColor(.secondary)
-                            Text("Pitch: \(String(format: "%.2f", trackingConstants.pitchDownThreshold)) to \(String(format: "%.2f", trackingConstants.pitchUpThreshold))")
-                                .font(.caption2)
-                                .foregroundColor(.secondary)
+                            Text(
+                                "Yaw Max: \(String(format: "%.2f", trackingConstants.yawThreshold))"
+                            )
+                            .font(.caption2)
+                            .foregroundColor(.secondary)
+                            Text(
+                                "Pitch: \(String(format: "%.2f", trackingConstants.pitchDownThreshold)) to \(String(format: "%.2f", trackingConstants.pitchUpThreshold))"
+                            )
+                            .font(.caption2)
+                            .foregroundColor(.secondary)
                         }
                     }
                 }

Gaze/Views/WindowClasses.swift

@@ -0,0 +1,20 @@
+//
+//  WindowClasses.swift
+//  Gaze
+//
+//  Custom NSWindow subclasses for different window behaviors.
+//
+
+import AppKit
+
+/// Window that accepts keyboard and mouse focus (for overlay reminders)
+class KeyableWindow: NSWindow {
+    override var canBecomeKey: Bool { true }
+    override var canBecomeMain: Bool { true }
+}
+
+/// Window that doesn't accept keyboard or mouse focus (for subtle reminders)
+class NonKeyWindow: NSWindow {
+    override var canBecomeKey: Bool { false }
+    override var canBecomeMain: Bool { false }
+}

GazeTests/Mocks/MockSettingsManager.swift

@@ -30,11 +30,17 @@ final class MockSettingsManager: ObservableObject, SettingsProviding {
     var saveCallCount = 0
     var loadCallCount = 0
     var resetToDefaultsCallCount = 0
+    var saveImmediatelyCallCount = 0
+    
+    /// Track timer configuration updates for verification
+    var timerConfigurationUpdates: [(TimerType, TimerConfiguration)] = []
     
     init(settings: AppSettings = .defaults) {
         self.settings = settings
     }
     
+    // MARK: - SettingsProviding conformance
+    
     func timerConfiguration(for type: TimerType) -> TimerConfiguration {
         guard let keyPath = timerConfigKeyPaths[type] else {
             preconditionFailure("Unknown timer type: \(type)")
@@ -47,6 +53,7 @@ final class MockSettingsManager: ObservableObject, SettingsProviding {
             preconditionFailure("Unknown timer type: \(type)")
         }
         settings[keyPath: keyPath] = configuration
+        timerConfigurationUpdates.append((type, configuration))
     }
     
     func allTimerConfigurations() -> [TimerType: TimerConfiguration] {
@@ -62,7 +69,7 @@ final class MockSettingsManager: ObservableObject, SettingsProviding {
     }
     
     func saveImmediately() {
-        saveCallCount += 1
+        saveImmediatelyCallCount += 1
     }
     
     func load() {
@@ -73,4 +80,81 @@ final class MockSettingsManager: ObservableObject, SettingsProviding {
         resetToDefaultsCallCount += 1
         settings = .defaults
     }
+    
+    // MARK: - Test helper methods
+    
+    /// Resets all call tracking counters
+    func resetCallTracking() {
+        saveCallCount = 0
+        loadCallCount = 0
+        resetToDefaultsCallCount = 0
+        saveImmediatelyCallCount = 0
+        timerConfigurationUpdates = []
+    }
+    
+    /// Creates settings with all timers enabled
+    static func withAllTimersEnabled() -> MockSettingsManager {
+        var settings = AppSettings.defaults
+        settings.lookAwayTimer.enabled = true
+        settings.blinkTimer.enabled = true
+        settings.postureTimer.enabled = true
+        return MockSettingsManager(settings: settings)
+    }
+    
+    /// Creates settings with all timers disabled
+    static func withAllTimersDisabled() -> MockSettingsManager {
+        var settings = AppSettings.defaults
+        settings.lookAwayTimer.enabled = false
+        settings.blinkTimer.enabled = false
+        settings.postureTimer.enabled = false
+        return MockSettingsManager(settings: settings)
+    }
+    
+    /// Creates settings with onboarding completed
+    static func withOnboardingCompleted() -> MockSettingsManager {
+        var settings = AppSettings.defaults
+        settings.hasCompletedOnboarding = true
+        return MockSettingsManager(settings: settings)
+    }
+    
+    /// Creates settings with custom timer intervals (in seconds)
+    static func withTimerIntervals(
+        lookAway: Int = 20 * 60,
+        blink: Int = 7 * 60,
+        posture: Int = 30 * 60
+    ) -> MockSettingsManager {
+        var settings = AppSettings.defaults
+        settings.lookAwayTimer.intervalSeconds = lookAway
+        settings.blinkTimer.intervalSeconds = blink
+        settings.postureTimer.intervalSeconds = posture
+        return MockSettingsManager(settings: settings)
+    }
+    
+    /// Enables a specific timer
+    func enableTimer(_ type: TimerType) {
+        guard let keyPath = timerConfigKeyPaths[type] else { return }
+        settings[keyPath: keyPath].enabled = true
+    }
+    
+    /// Disables a specific timer
+    func disableTimer(_ type: TimerType) {
+        guard let keyPath = timerConfigKeyPaths[type] else { return }
+        settings[keyPath: keyPath].enabled = false
+    }
+    
+    /// Sets a specific timer's interval
+    func setTimerInterval(_ type: TimerType, seconds: Int) {
+        guard let keyPath = timerConfigKeyPaths[type] else { return }
+        settings[keyPath: keyPath].intervalSeconds = seconds
+    }
+    
+    /// Adds a user timer
+    func addUserTimer(_ timer: UserTimer) {
+        settings.userTimers.append(timer)
+    }
+    
+    /// Removes all user timers
+    func clearUserTimers() {
+        settings.userTimers = []
+    }
 }

GazeTests/Mocks/MockWindowManager.swift

@@ -0,0 +1,101 @@
+//
+//  MockWindowManager.swift
+//  GazeTests
+//
+//  A mock implementation of WindowManaging for isolated unit testing.
+//
+
+import SwiftUI
+@testable import Gaze
+
+/// A mock implementation of WindowManaging that doesn't create real windows.
+/// This allows tests to run in complete isolation without affecting the UI.
+@MainActor
+final class MockWindowManager: WindowManaging {
+    
+    // MARK: - State tracking
+    
+    var isOverlayReminderVisible: Bool = false
+    var isSubtleReminderVisible: Bool = false
+    
+    // MARK: - Call tracking for verification
+    
+    var showReminderWindowCalls: [(windowType: ReminderWindowType, viewType: String)] = []
+    var dismissOverlayReminderCallCount = 0
+    var dismissSubtleReminderCallCount = 0
+    var dismissAllRemindersCallCount = 0
+    var showSettingsCalls: [Int] = []
+    var showOnboardingCallCount = 0
+    
+    /// The last window type shown
+    var lastShownWindowType: ReminderWindowType?
+    
+    // MARK: - WindowManaging conformance
+    
+    func showReminderWindow<Content: View>(_ content: Content, windowType: ReminderWindowType) {
+        let viewType = String(describing: type(of: content))
+        showReminderWindowCalls.append((windowType: windowType, viewType: viewType))
+        lastShownWindowType = windowType
+        
+        switch windowType {
+        case .overlay:
+            isOverlayReminderVisible = true
+        case .subtle:
+            isSubtleReminderVisible = true
+        }
+    }
+    
+    func dismissOverlayReminder() {
+        dismissOverlayReminderCallCount += 1
+        isOverlayReminderVisible = false
+    }
+    
+    func dismissSubtleReminder() {
+        dismissSubtleReminderCallCount += 1
+        isSubtleReminderVisible = false
+    }
+    
+    func dismissAllReminders() {
+        dismissAllRemindersCallCount += 1
+        isOverlayReminderVisible = false
+        isSubtleReminderVisible = false
+    }
+    
+    func showSettings(settingsManager: any SettingsProviding, initialTab: Int) {
+        showSettingsCalls.append(initialTab)
+    }
+    
+    func showOnboarding(settingsManager: any SettingsProviding) {
+        showOnboardingCallCount += 1
+    }
+    
+    // MARK: - Test helpers
+    
+    /// Resets all call tracking counters
+    func resetCallTracking() {
+        showReminderWindowCalls = []
+        dismissOverlayReminderCallCount = 0
+        dismissSubtleReminderCallCount = 0
+        dismissAllRemindersCallCount = 0
+        showSettingsCalls = []
+        showOnboardingCallCount = 0
+        lastShownWindowType = nil
+        isOverlayReminderVisible = false
+        isSubtleReminderVisible = false
+    }
+    
+    /// Returns the number of overlay windows shown
+    var overlayWindowsShownCount: Int {
+        showReminderWindowCalls.filter { $0.windowType == .overlay }.count
+    }
+    
+    /// Returns the number of subtle windows shown
+    var subtleWindowsShownCount: Int {
+        showReminderWindowCalls.filter { $0.windowType == .subtle }.count
+    }
+    
+    /// Checks if a specific view type was shown
+    func wasViewShown(containing typeName: String) -> Bool {
+        showReminderWindowCalls.contains { $0.viewType.contains(typeName) }
+    }
+}

GazeTests/TimerEngineTests.swift

@@ -12,25 +12,23 @@ import XCTest
 final class TimerEngineTests: XCTestCase {
     
     var timerEngine: TimerEngine!
-    var settingsManager: SettingsManager!
+    var mockSettings: MockSettingsManager!
     
     override func setUp() async throws {
         try await super.setUp()
-        settingsManager = SettingsManager.shared
-        UserDefaults.standard.removeObject(forKey: "gazeAppSettings")
-        settingsManager.load()
-        timerEngine = TimerEngine(settingsManager: settingsManager)
+        mockSettings = MockSettingsManager()
+        timerEngine = TimerEngine(settingsManager: mockSettings, enforceModeService: nil)
     }
     
     override func tearDown() async throws {
         timerEngine.stop()
-        UserDefaults.standard.removeObject(forKey: "gazeAppSettings")
+        mockSettings = nil
         try await super.tearDown()
     }
     
     func testTimerInitialization() {
         // Enable all timers for this test (blink is disabled by default)
-        settingsManager.settings.blinkTimer.enabled = true
+        mockSettings.enableTimer(.blink)
         timerEngine.start()
         
         XCTAssertEqual(timerEngine.timerStates.count, 3)
@@ -60,7 +58,7 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testPauseAllTimers() {
-        settingsManager.settings.blinkTimer.enabled = true
+        mockSettings.enableTimer(.blink)
         timerEngine.start()
         timerEngine.pause()
         
@@ -70,7 +68,7 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testResumeAllTimers() {
-        settingsManager.settings.blinkTimer.enabled = true
+        mockSettings.enableTimer(.blink)
         timerEngine.start()
         timerEngine.pause()
         timerEngine.resume()
@@ -81,7 +79,7 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testSkipNext() {
-        settingsManager.settings.lookAwayTimer.intervalSeconds = 60
+        mockSettings.setTimerInterval(.lookAway, seconds: 60)
         timerEngine.start()
         
         timerEngine.timerStates[.builtIn(.lookAway)]?.remainingSeconds = 10
@@ -123,8 +121,8 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testDismissReminderResetsTimer() {
-        settingsManager.settings.blinkTimer.enabled = true
-        settingsManager.settings.blinkTimer.intervalSeconds = 7 * 60
+        mockSettings.enableTimer(.blink)
+        mockSettings.setTimerInterval(.blink, seconds: 7 * 60)
         timerEngine.start()
         timerEngine.timerStates[.builtIn(.blink)]?.remainingSeconds = 0
         timerEngine.activeReminder = .blinkTriggered
@@ -156,7 +154,7 @@ final class TimerEngineTests: XCTestCase {
         
         XCTAssertNotNil(timerEngine.activeReminder)
         if case .lookAwayTriggered(let countdown) = timerEngine.activeReminder {
-            XCTAssertEqual(countdown, settingsManager.settings.lookAwayCountdownSeconds)
+            XCTAssertEqual(countdown, mockSettings.settings.lookAwayCountdownSeconds)
         } else {
             XCTFail("Expected lookAwayTriggered reminder")
         }
@@ -166,7 +164,7 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testTriggerReminderForBlink() {
-        settingsManager.settings.blinkTimer.enabled = true
+        mockSettings.enableTimer(.blink)
         timerEngine.start()
         
         timerEngine.triggerReminder(for: .builtIn(.blink))
@@ -260,7 +258,7 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testDismissBlinkReminderResumesTimer() {
-        settingsManager.settings.blinkTimer.enabled = true
+        mockSettings.enableTimer(.blink)
         timerEngine.start()
         timerEngine.triggerReminder(for: .builtIn(.blink))
         
@@ -281,9 +279,9 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testAllTimersStartWhenEnabled() {
-        settingsManager.settings.lookAwayTimer.enabled = true
-        settingsManager.settings.blinkTimer.enabled = true
-        settingsManager.settings.postureTimer.enabled = true
+        mockSettings.enableTimer(.lookAway)
+        mockSettings.enableTimer(.blink)
+        mockSettings.enableTimer(.posture)
         
         timerEngine.start()
         
@@ -294,9 +292,9 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testAllTimersDisabled() {
-        settingsManager.settings.lookAwayTimer.enabled = false
-        settingsManager.settings.blinkTimer.enabled = false
-        settingsManager.settings.postureTimer.enabled = false
+        mockSettings.disableTimer(.lookAway)
+        mockSettings.disableTimer(.blink)
+        mockSettings.disableTimer(.posture)
         
         timerEngine.start()
         
@@ -304,9 +302,9 @@ final class TimerEngineTests: XCTestCase {
     }
     
     func testPartialTimersEnabled() {
-        settingsManager.settings.lookAwayTimer.enabled = true
-        settingsManager.settings.blinkTimer.enabled = false
-        settingsManager.settings.postureTimer.enabled = true
+        mockSettings.enableTimer(.lookAway)
+        mockSettings.disableTimer(.blink)
+        mockSettings.enableTimer(.posture)
         
         timerEngine.start()
         
@@ -325,7 +323,7 @@ final class TimerEngineTests: XCTestCase {
             intervalMinutes: 1,
             message: "Drink water"
         )
-        settingsManager.settings.userTimers = [overlayTimer]
+        mockSettings.addUserTimer(overlayTimer)
         
         timerEngine.start()
         
@@ -345,7 +343,6 @@ final class TimerEngineTests: XCTestCase {
         XCTAssertTrue(timerEngine.isTimerPaused(.user(id: overlayTimer.id)))
         
         // Now trigger a subtle reminder (blink) while overlay is still active
-        let previousActiveReminder = timerEngine.activeReminder
         timerEngine.triggerReminder(for: .builtIn(.blink))
         
         // The activeReminder should be replaced with the blink reminder
@@ -360,16 +357,9 @@ final class TimerEngineTests: XCTestCase {
         // Both timers should be paused (the one that triggered their reminder)
         XCTAssertTrue(timerEngine.isTimerPaused(.user(id: overlayTimer.id)))
         XCTAssertTrue(timerEngine.isTimerPaused(.builtIn(.blink)))
-        
-        // The key insight: Even though TimerEngine only tracks one activeReminder,
-        // AppDelegate now tracks overlay and subtle windows separately, so both
-        // reminders can be displayed simultaneously without interference
     }
     
     func testOverlayReminderDoesNotBlockSubtleReminders() {
-        // This test verifies the fix for the bug where a subtle reminder
-        // would cause an overlay reminder to get stuck
-        
         // Setup overlay user timer
         let overlayTimer = UserTimer(
             title: "Stand Up",
@@ -377,9 +367,9 @@ final class TimerEngineTests: XCTestCase {
             timeOnScreenSeconds: 10,
             intervalMinutes: 1
         )
-        settingsManager.settings.userTimers = [overlayTimer]
-        settingsManager.settings.blinkTimer.enabled = true
-        settingsManager.settings.blinkTimer.intervalSeconds = 60
+        mockSettings.addUserTimer(overlayTimer)
+        mockSettings.enableTimer(.blink)
+        mockSettings.setTimerInterval(.blink, seconds: 60)
         
         timerEngine.start()
         
@@ -412,9 +402,53 @@ final class TimerEngineTests: XCTestCase {
         XCTAssertFalse(timerEngine.isTimerPaused(.builtIn(.blink)))
         XCTAssertEqual(timerEngine.timerStates[.builtIn(.blink)]?.remainingSeconds, 60)
         
-        // The overlay timer should still be paused (user needs to dismiss it manually)
-        // Note: In the actual app, AppDelegate tracks this window separately and it
-        // remains visible even after the subtle reminder dismisses
+        // The overlay timer should still be paused
         XCTAssertTrue(timerEngine.isTimerPaused(.user(id: overlayTimer.id)))
     }
+    
+    // MARK: - Tests using injectable time provider
+    
+    func testTimerEngineWithMockTimeProvider() {
+        let mockTime = MockTimeProvider(startTime: Date())
+        let engine = TimerEngine(
+            settingsManager: mockSettings,
+            enforceModeService: nil,
+            timeProvider: mockTime
+        )
+        
+        engine.start()
+        XCTAssertNotNil(engine.timerStates[.builtIn(.lookAway)])
+        
+        engine.stop()
+    }
+    
+    func testSystemSleepWakeWithMockTime() {
+        let startDate = Date()
+        let mockTime = MockTimeProvider(startTime: startDate)
+        let engine = TimerEngine(
+            settingsManager: mockSettings,
+            enforceModeService: nil,
+            timeProvider: mockTime
+        )
+        
+        engine.start()
+        let initialRemaining = engine.timerStates[.builtIn(.lookAway)]?.remainingSeconds ?? 0
+        
+        // Simulate sleep
+        engine.handleSystemSleep()
+        XCTAssertTrue(engine.isTimerPaused(.builtIn(.lookAway)))
+        
+        // Advance mock time by 5 minutes
+        mockTime.advance(by: 300)
+        
+        // Simulate wake
+        engine.handleSystemWake()
+        
+        // Timer should resume and have adjusted remaining time
+        XCTAssertFalse(engine.isTimerPaused(.builtIn(.lookAway)))
+        let newRemaining = engine.timerStates[.builtIn(.lookAway)]?.remainingSeconds ?? 0
+        XCTAssertEqual(newRemaining, initialRemaining - 300)
+        
+        engine.stop()
+    }
 }