From 1d351c209684ed785a840c5d041d017ed12ba64f Mon Sep 17 00:00:00 2001
From: Ariver <shanghai3168@gmail.com>
Date: Sat, 20 Jun 2026 01:44:54 +0800
Subject: [PATCH] Add Quick Switch theme toggle

---
 C3.tools/round1-main-ui-qa.sh                                |    3 
 C3.tools/round1-theme-toggle-fixture-qa.sh                   |  236 ++++++++++++++
 C1.source/Sources/Aligner/QuickSwitchRootView.swift          |  614 ++++++++++++++++++++++++++++++++++---
 C1.source/Resources/Aligner-Info.plist                       |    4 
 C1.source/Sources/Aligner/AlignerApplicationDelegate.swift   |   46 ++
 C1.source/Sources/Aligner/QuickSwitchSessionController.swift |   22 +
 CHANGELOG.md                                                 |   13 
 7 files changed, 877 insertions(+), 61 deletions(-)

diff --git a/C1.source/Resources/Aligner-Info.plist b/C1.source/Resources/Aligner-Info.plist
index d5f0831..0c386e9 100644
--- a/C1.source/Resources/Aligner-Info.plist
+++ b/C1.source/Resources/Aligner-Info.plist
@@ -17,9 +17,9 @@
 	<key>CFBundlePackageType</key>
 	<string>APPL</string>
 	<key>CFBundleShortVersionString</key>
-	<string>0.1.0</string>
+	<string>0.1.1</string>
 	<key>CFBundleVersion</key>
-	<string>20260619.2255</string>
+	<string>20260620.0136</string>
 	<key>LSMinimumSystemVersion</key>
 	<string>26.0</string>
 	<key>NSHighResolutionCapable</key>
diff --git a/C1.source/Sources/Aligner/AlignerApplicationDelegate.swift b/C1.source/Sources/Aligner/AlignerApplicationDelegate.swift
index 4ada6fd..89c2a16 100644
--- a/C1.source/Sources/Aligner/AlignerApplicationDelegate.swift
+++ b/C1.source/Sources/Aligner/AlignerApplicationDelegate.swift
@@ -481,6 +481,7 @@
                 windowCloseService: quickSwitchWindowCloseService(),
                 disableScreenshotRefresh: round1QuickSwitchOptions.disableScreenshotRefresh,
                 waterfallViewMode: quickSwitchWaterfallViewMode(),
+                theme: quickSwitchThemePreference(),
                 closeConfirmationRequired: quickSwitchConfirmBeforeClose,
                 onCloseConfirmationDisabled: { [weak self] in
                     self?.setQuickSwitchConfirmBeforeClose(false)
@@ -496,6 +497,9 @@
             }
             controller.onToggleWaterfallViewMode = { [weak self] in
                 self?.toggleQuickSwitchWaterfallViewModeFromQuickSwitch()
+            }
+            controller.onToggleTheme = { [weak self] in
+                self?.toggleQuickSwitchThemeFromQuickSwitch()
             }
             quickSwitchSessionController = controller
         }
@@ -560,6 +564,7 @@
                 windowCloseService: quickSwitchWindowCloseService(),
                 disableScreenshotRefresh: round1QuickSwitchOptions.disableScreenshotRefresh,
                 waterfallViewMode: quickSwitchWaterfallViewMode(),
+                theme: quickSwitchThemePreference(),
                 closeConfirmationRequired: quickSwitchConfirmBeforeClose,
                 onCloseConfirmationDisabled: { [weak self] in
                     self?.setQuickSwitchConfirmBeforeClose(false)
@@ -575,6 +580,9 @@
             }
             controller.onToggleWaterfallViewMode = { [weak self] in
                 self?.toggleQuickSwitchWaterfallViewModeFromQuickSwitch()
+            }
+            controller.onToggleTheme = { [weak self] in
+                self?.toggleQuickSwitchThemeFromQuickSwitch()
             }
             quickSwitchSessionController = controller
         }
@@ -607,6 +615,8 @@
         let versionBuild = appVersionBuild()
         report["preferenceWaterfallViewMode"] = preferenceStore.read().quickSwitchWaterfallViewMode.rawValue
         report["resolvedWaterfallViewMode"] = quickSwitchWaterfallViewMode().rawValue
+        report["preferenceTheme"] = preferenceStore.read().theme.rawValue
+        report["resolvedQuickSwitchTheme"] = quickSwitchThemePreference().rawValue
         report["aboutVersion"] = versionBuild.version
         report["aboutBuild"] = versionBuild.build
         report["statusMenu"] = statusMenuReportDictionary()
@@ -700,6 +710,11 @@
             ?? preferenceStore.read().quickSwitchWaterfallViewMode
     }
 
+    private func quickSwitchThemePreference() -> ThemePreference {
+        let theme = preferenceStore.read().theme
+        return theme == .dark ? .dark : .light
+    }
+
     private func quickSwitchSpaceActivationService() -> any SpaceActivationServiceProtocol {
         if round1QuickSwitchOptions.debugWindowActivation {
             return DebugSpaceActivationService()
@@ -762,6 +777,37 @@
         setQuickSwitchWaterfallViewMode(nextMode)
     }
 
+    private func setQuickSwitchThemePreference(_ theme: ThemePreference) {
+        let normalizedTheme: ThemePreference = theme == .dark ? .dark : .light
+        let preferences = preferenceStore.read()
+        let updatedPreferences = AlignerPreferences(
+            showMinimizedWindows: preferences.showMinimizedWindows,
+            showFullscreenWindows: preferences.showFullscreenWindows,
+            quickSwitchWaterfallViewMode: preferences.quickSwitchWaterfallViewMode,
+            theme: normalizedTheme,
+            language: preferences.language,
+            spaceDisplayStrategy: preferences.spaceDisplayStrategy
+        )
+        preferenceStore.write(updatedPreferences)
+        quickSwitchSessionController?.setTheme(normalizedTheme)
+        writeQuickSwitchReportIfNeeded()
+        DevelopmentDiagnostics.log("app.quickSwitch.themePreferenceChanged", [
+            "theme": normalizedTheme.rawValue,
+            "quickSwitchVisible": quickSwitchSessionController?.isVisible ?? false
+        ])
+    }
+
+    private func toggleQuickSwitchThemeFromQuickSwitch() {
+        let currentTheme = quickSwitchThemePreference()
+        let nextTheme: ThemePreference = currentTheme == .dark ? .light : .dark
+        DevelopmentDiagnostics.log("app.quickSwitch.themeToggle", [
+            "currentTheme": currentTheme.rawValue,
+            "nextTheme": nextTheme.rawValue,
+            "quickSwitchVisible": quickSwitchSessionController?.isVisible ?? false
+        ])
+        setQuickSwitchThemePreference(nextTheme)
+    }
+
     private func appVersionBuild() -> (version: String, build: String) {
         let info = Bundle.main.infoDictionary ?? [:]
         let version = info["CFBundleShortVersionString"] as? String ?? "Unknown"
diff --git a/C1.source/Sources/Aligner/QuickSwitchRootView.swift b/C1.source/Sources/Aligner/QuickSwitchRootView.swift
index 5fff479..f137091 100644
--- a/C1.source/Sources/Aligner/QuickSwitchRootView.swift
+++ b/C1.source/Sources/Aligner/QuickSwitchRootView.swift
@@ -25,6 +25,10 @@
     private let backdropBlurView = NSVisualEffectView()
     private let layerHostView = NSView()
     private let backgroundLayer = CAGradientLayer()
+    private let darkAmbientLeftLayer = CAGradientLayer()
+    private let darkAmbientCenterLayer = CAGradientLayer()
+    private let darkAmbientRightLayer = CAGradientLayer()
+    private let darkVignetteLayer = CAGradientLayer()
     private let safeAreaFillLayer = CALayer()
     private let glassLayer = CALayer()
     private let laneLayer = CALayer()
@@ -38,6 +42,8 @@
     private let closeFeedbackTextLayer = CATextLayer()
     private let viewModeToggleButtonLayer = CALayer()
     private let viewModeToggleIconLayer = CALayer()
+    private let themeToggleButtonLayer = CALayer()
+    private let themeToggleIconLayer = CALayer()
     private let appIconProvider: any AppIconProviderProtocol = WorkspaceAppIconProvider()
     private let skeletonThumbnailProvider = NativeSkeletonThumbnailProvider(size: NSSize(width: 160, height: 96))
     private var screenshotSourcesByWindowID: [UInt32: ScreenshotResolutionSource] = [:]
@@ -65,6 +71,8 @@
     private var closeFeedbackHideTask: Task<Void, Never>?
     private var isViewModeToggleButtonHovered = false
     private var suppressViewModeToggleHoverPreview = false
+    private var isThemeToggleButtonHovered = false
+    private var suppressThemeToggleHoverPreview = false
     private var hoverTarget: HoverTarget = .none
     private var hoverTargetSource: HoverTargetSource = .event
     private var hoveredSpaceLaneID: UInt64?
@@ -72,6 +80,7 @@
     private var debugHoveredAppGroupIndex: Int?
     private var waterfallColumns: [WaterfallColumnLayers] = []
     private var waterfallViewMode: QuickSwitchWaterfallViewMode = .verticalColumns
+    private var themePreference: ThemePreference = .light
     private var waterfallContentWidth: CGFloat = 0
     private var waterfallScrollOffset: CGFloat = 0
     private var waterfallColumnScrollOffsets: [Int: CGFloat] = [:]
@@ -121,6 +130,7 @@
     var onSpaceLaneClick: ((UInt64, Int) -> Void)?
     var onBackgroundClick: (() -> Bool)?
     var onToggleWaterfallViewMode: (() -> Void)?
+    var onToggleTheme: (() -> Void)?
     var onRequestClose: ((QuickSwitchCloseRequest) -> Void)?
     var onCloseConfirmationDisabled: (() -> Void)?
 
@@ -391,6 +401,118 @@
         case verticalSelected = "Z2"
     }
 
+    private enum ThemeToggleMetrics {
+        static let buttonGap: CGFloat = 10
+    }
+
+    private enum QuickSwitchResolvedTheme: String {
+        case light
+        case dark
+    }
+
+    private struct QuickSwitchThemePalette {
+        let resolvedTheme: QuickSwitchResolvedTheme
+        let backgroundGradientColors: [NSColor]
+        let safeAreaFill: NSColor
+        let displayGroupBackground: NSColor
+        let spaceLanePrimaryText: NSColor
+        let spaceLaneSecondaryText: NSColor
+        let columnBackground: NSColor
+        let columnBorder: NSColor
+        let columnHeaderBackground: NSColor
+        let columnHeaderHoverBackground: NSColor
+        let columnHeaderSpaceFocusedBackground: NSColor
+        let columnText: NSColor
+        let columnSecondaryText: NSColor
+        let cardBackground: NSColor
+        let cardSelectedBackground: NSColor
+        let cardText: NSColor
+        let cardSecondaryText: NSColor
+        let appShelfLabelText: NSColor
+        let appShelfIndexText: NSColor
+        let appShelfIndexHighlightedText: NSColor
+        let appShelfBackgroundSelected: NSColor
+        let appShelfBackgroundHovered: NSColor
+        let appShelfBackgroundSpaceFocused: NSColor
+        let closeFeedbackBackground: NSColor
+        let closeFeedbackBorder: NSColor
+        let closeFeedbackText: NSColor
+        let shinePeak: NSColor
+
+        static func palette(for theme: QuickSwitchResolvedTheme) -> QuickSwitchThemePalette {
+            switch theme {
+            case .light:
+                return QuickSwitchThemePalette(
+                    resolvedTheme: .light,
+                    backgroundGradientColors: [
+                        NSColor.windowBackgroundColor.withAlphaComponent(0.58),
+                        NSColor.controlBackgroundColor.withAlphaComponent(0.48)
+                    ],
+                    safeAreaFill: .black,
+                    displayGroupBackground: NSColor.windowBackgroundColor,
+                    spaceLanePrimaryText: .labelColor,
+                    spaceLaneSecondaryText: .secondaryLabelColor,
+                    columnBackground: NSColor.controlBackgroundColor.withAlphaComponent(0.56),
+                    columnBorder: NSColor.separatorColor.withAlphaComponent(0.24),
+                    columnHeaderBackground: NSColor.controlBackgroundColor.withAlphaComponent(0.52),
+                    columnHeaderHoverBackground: NSColor.systemGray.withAlphaComponent(0.22),
+                    columnHeaderSpaceFocusedBackground: NSColor.systemFill.withAlphaComponent(0.10),
+                    columnText: .labelColor,
+                    columnSecondaryText: .secondaryLabelColor,
+                    cardBackground: NSColor.windowBackgroundColor.withAlphaComponent(0.82),
+                    cardSelectedBackground: NSColor.windowBackgroundColor.withAlphaComponent(0.94),
+                    cardText: .labelColor,
+                    cardSecondaryText: .secondaryLabelColor,
+                    appShelfLabelText: .secondaryLabelColor,
+                    appShelfIndexText: NSColor.labelColor.withAlphaComponent(0.48),
+                    appShelfIndexHighlightedText: NSColor.labelColor.withAlphaComponent(0.58),
+                    appShelfBackgroundSelected: NSColor.controlAccentColor.withAlphaComponent(0.14),
+                    appShelfBackgroundHovered: NSColor.controlAccentColor.withAlphaComponent(0.13),
+                    appShelfBackgroundSpaceFocused: NSColor.controlAccentColor.withAlphaComponent(0.14),
+                    closeFeedbackBackground: NSColor.windowBackgroundColor.withAlphaComponent(0.94),
+                    closeFeedbackBorder: NSColor.separatorColor.withAlphaComponent(0.28),
+                    closeFeedbackText: NSColor.secondaryLabelColor.withAlphaComponent(0.96),
+                    shinePeak: NSColor.white.withAlphaComponent(0.16)
+                )
+            case .dark:
+                return QuickSwitchThemePalette(
+                    resolvedTheme: .dark,
+                    backgroundGradientColors: [
+                        NSColor(calibratedRed: 5 / 255, green: 8 / 255, blue: 20 / 255, alpha: 1),
+                        NSColor(calibratedRed: 15 / 255, green: 24 / 255, blue: 54 / 255, alpha: 1),
+                        NSColor(calibratedRed: 3 / 255, green: 42 / 255, blue: 52 / 255, alpha: 1),
+                        NSColor(calibratedRed: 2 / 255, green: 6 / 255, blue: 13 / 255, alpha: 1)
+                    ],
+                    safeAreaFill: .black,
+                    displayGroupBackground: NSColor(calibratedRed: 14 / 255, green: 24 / 255, blue: 39 / 255, alpha: 0.72),
+                    spaceLanePrimaryText: NSColor.white.withAlphaComponent(0.88),
+                    spaceLaneSecondaryText: NSColor.white.withAlphaComponent(0.56),
+                    columnBackground: NSColor(calibratedRed: 92 / 255, green: 97 / 255, blue: 111 / 255, alpha: 0.72),
+                    columnBorder: NSColor.white.withAlphaComponent(0.20),
+                    columnHeaderBackground: NSColor(calibratedRed: 104 / 255, green: 111 / 255, blue: 126 / 255, alpha: 0.70),
+                    columnHeaderHoverBackground: NSColor(calibratedRed: 185 / 255, green: 190 / 255, blue: 205 / 255, alpha: 0.32),
+                    columnHeaderSpaceFocusedBackground: NSColor(calibratedRed: 92 / 255, green: 171 / 255, blue: 255 / 255, alpha: 0.16),
+                    columnText: NSColor.black.withAlphaComponent(0.82),
+                    columnSecondaryText: NSColor.black.withAlphaComponent(0.46),
+                    cardBackground: NSColor.white.withAlphaComponent(0.90),
+                    cardSelectedBackground: NSColor.white.withAlphaComponent(0.96),
+                    cardText: NSColor.black.withAlphaComponent(0.86),
+                    cardSecondaryText: NSColor.black.withAlphaComponent(0.52),
+                    appShelfLabelText: NSColor.white.withAlphaComponent(0.66),
+                    appShelfIndexText: NSColor.white.withAlphaComponent(0.40),
+                    appShelfIndexHighlightedText: NSColor.white.withAlphaComponent(0.58),
+                    appShelfBackgroundSelected: NSColor(calibratedRed: 92 / 255, green: 171 / 255, blue: 255 / 255, alpha: 0.22),
+                    appShelfBackgroundHovered: NSColor(calibratedRed: 92 / 255, green: 171 / 255, blue: 255 / 255, alpha: 0.18),
+                    appShelfBackgroundSpaceFocused: NSColor(calibratedRed: 92 / 255, green: 171 / 255, blue: 255 / 255, alpha: 0.20),
+                    closeFeedbackBackground: NSColor(calibratedRed: 36 / 255, green: 43 / 255, blue: 58 / 255, alpha: 0.96),
+                    closeFeedbackBorder: NSColor.white.withAlphaComponent(0.18),
+                    closeFeedbackText: NSColor.white.withAlphaComponent(0.76),
+                    shinePeak: NSColor.white.withAlphaComponent(0.10)
+                )
+            }
+        }
+    }
+
     private enum WaterfallMetrics {
         static let gap: CGFloat = 16
         static let columnWidth: CGFloat = 252
@@ -575,15 +697,24 @@
         clearWindowIndexKeyPending()
 
         let toggleHovered = viewModeToggleButtonContains(windowLocation: event.locationInWindow)
+        let themeHovered = themeToggleButtonContains(windowLocation: event.locationInWindow)
         if !toggleHovered {
             suppressViewModeToggleHoverPreview = false
+        }
+        if !themeHovered {
+            suppressThemeToggleHoverPreview = false
         }
         let shouldShowToggleHoverPreview = toggleHovered && !suppressViewModeToggleHoverPreview
         if isViewModeToggleButtonHovered != shouldShowToggleHoverPreview {
             isViewModeToggleButtonHovered = shouldShowToggleHoverPreview
             needsLayout = true
         }
-        if toggleHovered {
+        let shouldShowThemeHoverPreview = themeHovered && !suppressThemeToggleHoverPreview
+        if isThemeToggleButtonHovered != shouldShowThemeHoverPreview {
+            isThemeToggleButtonHovered = shouldShowThemeHoverPreview
+            needsLayout = true
+        }
+        if toggleHovered || themeHovered {
             hoveredCloseTarget = nil
             setHoverTarget(.none)
             return
@@ -602,6 +733,8 @@
         clearWindowIndexKeyPending()
         isViewModeToggleButtonHovered = false
         suppressViewModeToggleHoverPreview = false
+        isThemeToggleButtonHovered = false
+        suppressThemeToggleHoverPreview = false
         hoveredCloseTarget = nil
         setHoverTarget(.none)
     }
@@ -623,6 +756,11 @@
 
         if viewModeToggleButtonContains(windowLocation: event.locationInWindow) {
             clickViewModeToggleButton(source: "mouse")
+            return
+        }
+
+        if themeToggleButtonContains(windowLocation: event.locationInWindow) {
+            clickThemeToggleButton(source: "mouse")
             return
         }
 
@@ -785,6 +923,15 @@
         waterfallColumnScrollOffsets = [:]
         horizontalMasonryScrollOffset = 0
         horizontalMasonryContentHeight = 0
+        needsLayout = true
+    }
+
+    func setTheme(_ theme: ThemePreference) {
+        let normalizedTheme = Self.normalizedQuickSwitchTheme(theme)
+        guard themePreference != normalizedTheme else { return }
+
+        themePreference = normalizedTheme
+        applyThemeToBackdrop()
         needsLayout = true
     }
 
@@ -1301,6 +1448,20 @@
             "viewModeToggleStandardBlueColor": colorDictionary(from: viewModeToggleBlueColor.cgColor),
             "viewModeToggleGlyphLineWidth": Double(ViewModeToggleMetrics.glyphLineWidth),
             "viewModeToggleAccessibilityLabel": viewModeToggleAccessibilityLabel,
+            "themeCurrentPreference": themePreference.rawValue,
+            "themeResolved": resolvedTheme.rawValue,
+            "themeNextPreference": nextThemePreference.rawValue,
+            "themeToggleButtonVisible": !themeToggleButtonLayer.isHidden,
+            "themeToggleButtonHovered": isThemeToggleButtonHovered,
+            "themeToggleHoverPreviewSuppressed": suppressThemeToggleHoverPreview,
+            "themeToggleButtonFrame": dictionary(from: themeToggleButtonLayer.frame),
+            "themeToggleHitSize": Double(ViewModeToggleMetrics.hitSize),
+            "themeToggleVisualSize": Double(ViewModeToggleMetrics.visualSize),
+            "themeToggleIconKind": "halfDisk",
+            "themeToggleAccessibilityLabel": themeToggleAccessibilityLabel,
+            "darkBackdropLayerCount": darkBackdropLayerCount,
+            "darkBackdropLayersVisible": darkBackdropLayersVisible,
+            "darkBackdropBackgroundGradientColors": backgroundGradientColorReports(),
             "settingsButtonVisible": false,
             "spaceFocusAppGroupIndexes": spaceFocusedAppGroupIndexes(),
             "appHoverAssociatedSpaceIDs": appHoverAssociatedSpaceIDs.sorted(),
@@ -1961,11 +2122,22 @@
             recordMouseCommand("hover-view-toggle")
             suppressViewModeToggleHoverPreview = false
             isViewModeToggleButtonHovered = true
+            isThemeToggleButtonHovered = false
             hoveredCloseTarget = nil
             setHoverTarget(.none, source: .debug)
         case "click-view-toggle", "click-settings":
             recordMouseCommand("click-view-toggle")
             clickViewModeToggleButton(source: "debug")
+        case "hover-theme-toggle":
+            recordMouseCommand("hover-theme-toggle")
+            suppressThemeToggleHoverPreview = false
+            isThemeToggleButtonHovered = true
+            isViewModeToggleButtonHovered = false
+            hoveredCloseTarget = nil
+            setHoverTarget(.none, source: .debug)
+        case "click-theme-toggle":
+            recordMouseCommand("click-theme-toggle")
+            clickThemeToggleButton(source: "debug")
         case "hover-card" where parts.count == 3:
             guard let appGroupIndex = Int(parts[1]), let windowIndex = Int(parts[2]) else {
                 recordMouseCommand("invalid:\(command)")
@@ -3210,7 +3382,7 @@
     }
 
     private func setupBackdropBlurView() {
-        backdropBlurView.material = .fullScreenUI
+        backdropBlurView.material = resolvedTheme == .dark ? .hudWindow : .fullScreenUI
         backdropBlurView.blendingMode = .behindWindow
         backdropBlurView.state = .active
         backdropBlurView.isEmphasized = false
@@ -3228,19 +3400,91 @@
         addSubview(layerHostView, positioned: .above, relativeTo: backdropBlurView)
     }
 
+    private func applyThemeToBackdrop() {
+        let palette = themePalette
+        backdropBlurView.material = resolvedTheme == .dark ? .hudWindow : .fullScreenUI
+        backgroundLayer.colors = palette.backgroundGradientColors.map(\.cgColor)
+        backgroundLayer.locations = resolvedTheme == .dark
+            ? [0, 0.44, 0.72, 1].map(NSNumber.init(value:))
+            : [0, 1].map(NSNumber.init(value:))
+        safeAreaFillLayer.backgroundColor = palette.safeAreaFill.cgColor
+
+        let showsDarkBackdrop = resolvedTheme == .dark
+        darkAmbientLeftLayer.isHidden = !showsDarkBackdrop
+        darkAmbientCenterLayer.isHidden = !showsDarkBackdrop
+        darkAmbientRightLayer.isHidden = !showsDarkBackdrop
+        darkVignetteLayer.isHidden = !showsDarkBackdrop
+        guard showsDarkBackdrop else { return }
+
+        darkAmbientLeftLayer.colors = [
+            NSColor(calibratedRed: 72 / 255, green: 56 / 255, blue: 145 / 255, alpha: 0.34).cgColor,
+            NSColor(calibratedRed: 20 / 255, green: 28 / 255, blue: 76 / 255, alpha: 0.17).cgColor,
+            NSColor.clear.cgColor
+        ]
+        darkAmbientCenterLayer.colors = [
+            NSColor(calibratedRed: 14 / 255, green: 92 / 255, blue: 130 / 255, alpha: 0.26).cgColor,
+            NSColor(calibratedRed: 12 / 255, green: 54 / 255, blue: 89 / 255, alpha: 0.16).cgColor,
+            NSColor.clear.cgColor
+        ]
+        darkAmbientRightLayer.colors = [
+            NSColor(calibratedRed: 4 / 255, green: 92 / 255, blue: 108 / 255, alpha: 0.20).cgColor,
+            NSColor(calibratedRed: 0 / 255, green: 44 / 255, blue: 54 / 255, alpha: 0.15).cgColor,
+            NSColor.clear.cgColor
+        ]
+        darkVignetteLayer.colors = [
+            NSColor.black.withAlphaComponent(0.48).cgColor,
+            NSColor.clear.cgColor,
+            NSColor.black.withAlphaComponent(0.28).cgColor
+        ]
+        darkVignetteLayer.locations = [0, 0.36, 1].map(NSNumber.init(value:))
+    }
+
+    private func layoutBackdropLayers() {
+        applyThemeToBackdrop()
+        guard resolvedTheme == .dark else { return }
+
+        let width = max(1, bounds.width)
+        let height = max(1, bounds.height)
+        darkAmbientLeftLayer.frame = CGRect(
+            x: -width * 0.18,
+            y: -height * 0.10,
+            width: width * 0.82,
+            height: height * 1.24
+        )
+        darkAmbientCenterLayer.frame = CGRect(
+            x: width * 0.24,
+            y: height * 0.10,
+            width: width * 0.52,
+            height: height * 0.74
+        )
+        darkAmbientRightLayer.frame = CGRect(
+            x: width * 0.50,
+            y: -height * 0.12,
+            width: width * 0.72,
+            height: height * 1.26
+        )
+        darkVignetteLayer.frame = bounds
+    }
+
     private func setupLayers() {
         guard let rootLayer = layerHostView.layer else { return }
 
         rootLayer.masksToBounds = true
-        backgroundLayer.colors = [
-            NSColor.windowBackgroundColor.withAlphaComponent(0.58).cgColor,
-            NSColor.controlBackgroundColor.withAlphaComponent(0.48).cgColor
-        ]
         backgroundLayer.startPoint = CGPoint(x: 0.5, y: 1.0)
         backgroundLayer.endPoint = CGPoint(x: 0.5, y: 0.0)
         rootLayer.addSublayer(backgroundLayer)
+        for ambientLayer in darkBackdropAmbientLayers {
+            ambientLayer.type = .radial
+            ambientLayer.startPoint = CGPoint(x: 0.5, y: 0.5)
+            ambientLayer.endPoint = CGPoint(x: 1.0, y: 1.0)
+            ambientLayer.isHidden = true
+            rootLayer.addSublayer(ambientLayer)
+        }
+        darkVignetteLayer.startPoint = CGPoint(x: 0.5, y: 1.0)
+        darkVignetteLayer.endPoint = CGPoint(x: 0.5, y: 0.0)
+        darkVignetteLayer.isHidden = true
+        rootLayer.addSublayer(darkVignetteLayer)
 
-        safeAreaFillLayer.backgroundColor = NSColor.black.cgColor
         rootLayer.addSublayer(safeAreaFillLayer)
 
         glassLayer.cornerRadius = 0
@@ -3297,6 +3541,18 @@
         viewModeToggleIconLayer.contentsScale = backingScaleFactor
         viewModeToggleButtonLayer.addSublayer(viewModeToggleIconLayer)
         glassLayer.addSublayer(viewModeToggleButtonLayer)
+
+        themeToggleButtonLayer.cornerRadius = 10
+        themeToggleButtonLayer.masksToBounds = false
+        themeToggleButtonLayer.borderWidth = 1
+        themeToggleButtonLayer.shadowColor = NSColor.black.cgColor
+        themeToggleButtonLayer.shadowOffset = CGSize(width: 0, height: -2)
+        themeToggleButtonLayer.zPosition = 170
+        themeToggleIconLayer.contentsScale = backingScaleFactor
+        themeToggleButtonLayer.addSublayer(themeToggleIconLayer)
+        glassLayer.addSublayer(themeToggleButtonLayer)
+
+        applyThemeToBackdrop()
     }
 
     private func rebuildAppShelfItems() {
@@ -3337,7 +3593,7 @@
                 string: item.app.name,
                 fontSize: 11,
                 weight: .regular,
-                color: .secondaryLabelColor,
+                color: themePalette.appShelfLabelText,
                 alignment: .center
             )
 
@@ -3389,8 +3645,8 @@
             container.name = column.app.name
             container.cornerRadius = 14
             container.masksToBounds = true
-            container.backgroundColor = NSColor.controlBackgroundColor.withAlphaComponent(0.56).cgColor
-            container.borderColor = NSColor.separatorColor.withAlphaComponent(0.34).cgColor
+            container.backgroundColor = themePalette.columnBackground.cgColor
+            container.borderColor = themePalette.columnBorder.cgColor
             container.borderWidth = 1
 
             let cardsClip = CALayer()
@@ -3398,21 +3654,21 @@
             cardsClip.backgroundColor = NSColor.clear.cgColor
 
             let header = CALayer()
-            header.backgroundColor = NSColor.controlBackgroundColor.withAlphaComponent(0.68).cgColor
+            header.backgroundColor = themePalette.columnHeaderBackground.cgColor
             header.zPosition = 40
 
             let appName = makeTextLayer(
                 string: column.app.name,
                 fontSize: 13,
                 weight: .semibold,
-                color: .labelColor,
+                color: themePalette.columnText,
                 alignment: .center
             )
             let count = makeTextLayer(
                 string: "\(column.windows.count)",
                 fontSize: 11,
                 weight: .medium,
-                color: .secondaryLabelColor,
+                color: themePalette.columnSecondaryText,
                 alignment: .right
             )
 
@@ -3444,14 +3700,14 @@
                     string: window.window.title.isEmpty ? "Untitled Window" : window.window.title,
                     fontSize: 12,
                     weight: .medium,
-                    color: .labelColor
+                    color: themePalette.cardText
                 )
                 title.truncationMode = .middle
                 let meta = makeTextLayer(
                     string: waterfallMetaText(for: window),
                     fontSize: 10,
                     weight: .regular,
-                    color: .secondaryLabelColor,
+                    color: themePalette.cardSecondaryText,
                     alignment: .right
                 )
                 let appIcon = CALayer()
@@ -3465,13 +3721,13 @@
                     string: waterfallStateText(for: window),
                     fontSize: 10,
                     weight: .medium,
-                    color: .secondaryLabelColor,
+                    color: themePalette.cardSecondaryText,
                     alignment: .right
                 )
                 let shine = CAGradientLayer()
                 shine.colors = [
                     NSColor.white.withAlphaComponent(0.00).cgColor,
-                    NSColor.white.withAlphaComponent(0.16).cgColor,
+                    themePalette.shinePeak.cgColor,
                     NSColor.white.withAlphaComponent(0.00).cgColor
                 ]
                 shine.startPoint = CGPoint(x: 0, y: 1)
@@ -3535,7 +3791,7 @@
             groupContainer.masksToBounds = false
             groupContainer.borderWidth = 0
             groupContainer.borderColor = NSColor.clear.cgColor
-            groupContainer.backgroundColor = NSColor.windowBackgroundColor.cgColor
+            groupContainer.backgroundColor = themePalette.displayGroupBackground.cgColor
             groupContainer.shadowColor = NSColor.black.cgColor
             groupContainer.shadowOpacity = 0
             groupContainer.shadowRadius = 0
@@ -3556,20 +3812,20 @@
                     string: space.label,
                     fontSize: 15,
                     weight: .semibold,
-                    color: .labelColor
+                    color: themePalette.spaceLanePrimaryText
                 )
                 let countLayer = makeTextLayer(
                     string: "\(space.windowCount)",
                     fontSize: 12,
                     weight: .medium,
-                    color: .secondaryLabelColor,
+                    color: themePalette.spaceLaneSecondaryText,
                     alignment: .center
                 )
                 let appLayer = makeTextLayer(
                     string: appIdentifierText(for: space),
                     fontSize: 12,
                     weight: space.type == .fullscreen ? .medium : .regular,
-                    color: space.type == .fullscreen ? .labelColor : .secondaryLabelColor,
+                    color: space.type == .fullscreen ? themePalette.spaceLanePrimaryText : themePalette.spaceLaneSecondaryText,
                     alignment: space.type == .fullscreen ? .center : .left
                 )
                 let splitAppLayers = splitViewAppNames(for: space).map { name in
@@ -3577,7 +3833,7 @@
                         string: name,
                         fontSize: 12,
                         weight: .medium,
-                        color: .labelColor,
+                        color: themePalette.spaceLanePrimaryText,
                         alignment: .center
                     )
                 }
@@ -3630,6 +3886,7 @@
         CATransaction.setDisableActions(true)
 
         backgroundLayer.frame = bounds
+        layoutBackdropLayers()
 
         let safeAreaTopInset = topSafeAreaInset
         safeAreaFillLayer.frame = CGRect(
@@ -3673,6 +3930,7 @@
         layoutCloseConfirmation()
         layoutCloseFeedback()
         layoutViewModeToggleButton()
+        layoutThemeToggleButton()
 
         CATransaction.commit()
     }
@@ -3694,7 +3952,7 @@
         let isSelectedState = viewModeToggleVisualStateIsSelected(visualState)
         viewModeToggleButtonLayer.backgroundColor = (isSelectedState
             ? viewModeToggleBlueColor
-            : NSColor.windowBackgroundColor.withAlphaComponent(isViewModeToggleButtonHovered ? 0.76 : 0.58)
+            : toggleIdleBackgroundColor(hovered: isViewModeToggleButtonHovered)
         ).cgColor
         viewModeToggleButtonLayer.borderColor = (isSelectedState
             ? viewModeToggleBlueColor.withAlphaComponent(0.96)
@@ -3708,6 +3966,45 @@
         let iconInset = ViewModeToggleMetrics.iconInset
         viewModeToggleIconLayer.frame = viewModeToggleButtonLayer.bounds.insetBy(dx: iconInset, dy: iconInset)
         layoutViewModeToggleIcon()
+    }
+
+    private func layoutThemeToggleButton() {
+        let size = ViewModeToggleMetrics.visualSize
+        let topMargin = topSafeAreaInset + RootLayoutMetrics.topContentMargin
+        let viewModeFrame = viewModeToggleButtonLayer.frame
+        let fallbackX = max(
+            RootLayoutMetrics.horizontalMargin,
+            glassLayer.bounds.width - RootLayoutMetrics.horizontalMargin - size * 2 - ThemeToggleMetrics.buttonGap
+        )
+        let x = max(
+            RootLayoutMetrics.horizontalMargin,
+            (viewModeFrame.width > 0 ? viewModeFrame.minX : fallbackX + size + ThemeToggleMetrics.buttonGap)
+                - ThemeToggleMetrics.buttonGap
+                - size
+        )
+        let y = max(
+            RootLayoutMetrics.bottomMargin,
+            glassLayer.bounds.height - topMargin - size
+        )
+        themeToggleButtonLayer.frame = CGRect(x: x, y: y, width: size, height: size)
+        themeToggleButtonLayer.cornerRadius = ViewModeToggleMetrics.cornerRadius
+        let isSelectedState = resolvedTheme == .dark
+        themeToggleButtonLayer.backgroundColor = (isSelectedState
+            ? viewModeToggleBlueColor
+            : themeToggleIdleBackgroundColor
+        ).cgColor
+        themeToggleButtonLayer.borderColor = (isSelectedState
+            ? viewModeToggleBlueColor.withAlphaComponent(0.96)
+            : viewModeToggleBlueColor.withAlphaComponent(isThemeToggleButtonHovered ? 0.72 : 0.34)
+        ).cgColor
+        themeToggleButtonLayer.shadowOpacity = isSelectedState ? 0.18 : (isThemeToggleButtonHovered ? 0.12 : 0.06)
+        themeToggleButtonLayer.shadowRadius = isSelectedState
+            ? ViewModeToggleMetrics.selectedShadowRadius
+            : ViewModeToggleMetrics.idleShadowRadius
+        themeToggleIconLayer.contentsScale = backingScaleFactor
+        let iconInset = ViewModeToggleMetrics.iconInset
+        themeToggleIconLayer.frame = themeToggleButtonLayer.bounds.insetBy(dx: iconInset, dy: iconInset)
+        layoutThemeToggleIcon()
     }
 
     private func layoutViewModeToggleIcon() {
@@ -3747,6 +4044,88 @@
         }
 
         CATransaction.commit()
+    }
+
+    private func layoutThemeToggleIcon() {
+        CATransaction.begin()
+        CATransaction.setDisableActions(true)
+        themeToggleIconLayer.sublayers?.forEach { $0.removeFromSuperlayer() }
+
+        let bounds = themeToggleIconLayer.bounds
+        guard bounds.width > 0, bounds.height > 0 else {
+            CATransaction.commit()
+            return
+        }
+
+        let isSelectedState = resolvedTheme == .dark
+        let strokeColor = isSelectedState
+            ? NSColor.white.withAlphaComponent(0.98)
+            : viewModeToggleBlueColor.withAlphaComponent(0.96)
+        let lightFillColor = isSelectedState
+            ? NSColor.white.withAlphaComponent(0.22)
+            : viewModeToggleBlueColor.withAlphaComponent(0.06)
+        let darkFillColor = isSelectedState
+            ? NSColor.white.withAlphaComponent(0.96)
+            : viewModeToggleBlueColor.withAlphaComponent(0.82)
+        let glyphRect = centeredSquare(in: bounds).insetBy(dx: 0.75, dy: 0.75)
+        addThemeToggleHalfDiskGlyph(
+            in: glyphRect,
+            strokeColor: strokeColor,
+            lightFillColor: lightFillColor,
+            darkFillColor: darkFillColor
+        )
+
+        CATransaction.commit()
+    }
+
+    private func addThemeToggleHalfDiskGlyph(
+        in rect: CGRect,
+        strokeColor: NSColor,
+        lightFillColor: NSColor,
+        darkFillColor: NSColor
+    ) {
+        let circlePath = CGPath(
+            ellipseIn: rect,
+            transform: nil
+        )
+        let baseLayer = CAShapeLayer()
+        baseLayer.contentsScale = backingScaleFactor
+        baseLayer.frame = themeToggleIconLayer.bounds
+        baseLayer.path = circlePath
+        baseLayer.fillColor = lightFillColor.cgColor
+        baseLayer.strokeColor = NSColor.clear.cgColor
+        themeToggleIconLayer.addSublayer(baseLayer)
+
+        let radius = min(rect.width, rect.height) / 2
+        let center = CGPoint(x: rect.midX, y: rect.midY)
+        let halfPath = CGMutablePath()
+        halfPath.move(to: CGPoint(x: center.x, y: center.y + radius))
+        halfPath.addArc(
+            center: center,
+            radius: radius,
+            startAngle: .pi / 2,
+            endAngle: .pi * 1.5,
+            clockwise: false
+        )
+        halfPath.closeSubpath()
+
+        let halfLayer = CAShapeLayer()
+        halfLayer.contentsScale = backingScaleFactor
+        halfLayer.frame = themeToggleIconLayer.bounds
+        halfLayer.path = halfPath
+        halfLayer.fillColor = darkFillColor.cgColor
+        halfLayer.strokeColor = NSColor.clear.cgColor
+        themeToggleIconLayer.addSublayer(halfLayer)
+
+        let outlineLayer = CAShapeLayer()
+        outlineLayer.contentsScale = backingScaleFactor
+        outlineLayer.frame = themeToggleIconLayer.bounds
+        outlineLayer.path = circlePath
+        outlineLayer.fillColor = NSColor.clear.cgColor
+        outlineLayer.strokeColor = strokeColor.cgColor
+        outlineLayer.lineWidth = ViewModeToggleMetrics.glyphLineWidth
+        outlineLayer.lineJoin = .round
+        themeToggleIconLayer.addSublayer(outlineLayer)
     }
 
     private func addVerticalColumnsToggleGlyph(
@@ -3992,7 +4371,7 @@
                 || segment.space.id == currentViewModel?.lockedSpaceID
         }
         let hasCurrentSegment = group.display.spaces.contains { $0.isCurrent }
-        group.containerLayer.backgroundColor = NSColor.windowBackgroundColor.cgColor
+        group.containerLayer.backgroundColor = themePalette.displayGroupBackground.cgColor
         group.containerLayer.borderColor = NSColor.clear.cgColor
         group.containerLayer.borderWidth = 0
         group.containerLayer.shadowOpacity = 0
@@ -4023,8 +4402,8 @@
                 : hasWindows
                     ? spaceLaneOccupiedColor.withAlphaComponent(isCurrent ? 0.54 : 0.44)
                 : isCurrent
-                    ? NSColor.labelColor.withAlphaComponent(0.34)
-                : NSColor.separatorColor.withAlphaComponent(0.34)
+                    ? themePalette.spaceLanePrimaryText.withAlphaComponent(0.34)
+                : themePalette.columnBorder.withAlphaComponent(resolvedTheme == .dark ? 0.58 : 0.34)
         ).cgColor
         if isLocked {
             applySpaceLaneSolidFill(
@@ -4079,13 +4458,13 @@
     }
 
     private func applySpaceLaneContentVisualState(_ segment: SpaceLaneSegmentLayers, isLocked: Bool) {
-        let primaryTextColor: NSColor = isLocked ? .white : .labelColor
+        let primaryTextColor: NSColor = isLocked ? .white : themePalette.spaceLanePrimaryText
         let secondaryTextColor: NSColor = isLocked
             ? .white
-            : .secondaryLabelColor
+            : themePalette.spaceLaneSecondaryText
 
         segment.labelLayer.foregroundColor = primaryTextColor.cgColor
-        segment.countLayer.foregroundColor = (isLocked ? NSColor.white : .secondaryLabelColor).cgColor
+        segment.countLayer.foregroundColor = (isLocked ? NSColor.white : themePalette.spaceLaneSecondaryText).cgColor
         segment.appLayer.foregroundColor = (segment.space.type == .fullscreen
             ? primaryTextColor
             : secondaryTextColor
@@ -4103,7 +4482,7 @@
 
         (segment.fullscreenMarkerLayer as? CAShapeLayer)?.strokeColor = (isLocked
             ? NSColor.white
-            : NSColor.secondaryLabelColor.withAlphaComponent(segment.space.isCurrent ? 0.42 : 0.28)
+            : themePalette.spaceLaneSecondaryText.withAlphaComponent(segment.space.isCurrent ? 0.72 : 0.54)
         ).cgColor
     }
 
@@ -4189,6 +4568,18 @@
             .contains(locationInGlass)
     }
 
+    private func themeToggleButtonContains(windowLocation: CGPoint) -> Bool {
+        let locationInView = convert(windowLocation, from: nil)
+        let locationInGlass = CGPoint(
+            x: locationInView.x - glassLayer.frame.minX,
+            y: locationInView.y - glassLayer.frame.minY
+        )
+        let hitOutset = (ViewModeToggleMetrics.hitSize - ViewModeToggleMetrics.visualSize) / 2
+        return themeToggleButtonLayer.frame
+            .insetBy(dx: -hitOutset, dy: -hitOutset)
+            .contains(locationInGlass)
+    }
+
     private func clickViewModeToggleButton(source: String) {
         DevelopmentDiagnostics.log("quickSwitch.view.clickWaterfallViewModeToggle", [
             "source": source,
@@ -4202,6 +4593,21 @@
         isViewModeToggleButtonHovered = false
         suppressViewModeToggleHoverPreview = true
         onToggleWaterfallViewMode?()
+    }
+
+    private func clickThemeToggleButton(source: String) {
+        DevelopmentDiagnostics.log("quickSwitch.view.clickThemeToggle", [
+            "source": source,
+            "currentTheme": resolvedTheme.rawValue,
+            "targetTheme": nextThemePreference.rawValue
+        ])
+        lastMouseCommand = "click-theme-toggle"
+        if !mouseCommandsApplied.contains("click-theme-toggle") {
+            mouseCommandsApplied.append("click-theme-toggle")
+        }
+        isThemeToggleButtonHovered = false
+        suppressThemeToggleHoverPreview = true
+        onToggleTheme?()
     }
 
     private func appShelfItem(at windowLocation: CGPoint) -> AppShelfItemLayers? {
@@ -4437,6 +4843,7 @@
             highlighted: showsSelectedVisual || isHovered
         )
         item.labelLayer.contentsScale = backingScaleFactor
+        item.labelLayer.foregroundColor = themePalette.appShelfLabelText.cgColor
         item.labelLayer.frame = CGRect(x: 0, y: 0, width: bounds.width, height: 14)
         item.badgeLayer.string = badgeText
         item.badgeLayer.isHidden = badgeText.isEmpty
@@ -4464,11 +4871,11 @@
     }
 
     private var appShelfIndexColor: NSColor {
-        NSColor.labelColor.withAlphaComponent(0.48)
+        themePalette.appShelfIndexText
     }
 
     private var appShelfIndexHighlightedColor: NSColor {
-        NSColor.labelColor.withAlphaComponent(0.58)
+        themePalette.appShelfIndexHighlightedText
     }
 
     private func appShelfIndexFont(size: CGFloat) -> NSFont {
@@ -4693,13 +5100,13 @@
 
     private func appShelfBackgroundColor(selected: Bool, hovered: Bool, spaceFocused: Bool) -> NSColor {
         if selected {
-            return NSColor.controlAccentColor.withAlphaComponent(0.14)
+            return themePalette.appShelfBackgroundSelected
         }
         if hovered {
-            return NSColor.controlAccentColor.withAlphaComponent(0.13)
+            return themePalette.appShelfBackgroundHovered
         }
         if spaceFocused {
-            return NSColor.controlAccentColor.withAlphaComponent(0.14)
+            return themePalette.appShelfBackgroundSpaceFocused
         }
         return .clear
     }
@@ -4724,7 +5131,7 @@
     }
 
     private var waterfallAppHoverHeaderFillColor: NSColor {
-        NSColor.systemGray.withAlphaComponent(0.22)
+        themePalette.columnHeaderHoverBackground
     }
 
     private var appShelfMaxScrollOffset: CGFloat {
@@ -4939,7 +5346,7 @@
     private func layoutWaterfallColumn(_ column: WaterfallColumnLayers) {
         column.containerLayer.cornerRadius = 14
         column.containerLayer.masksToBounds = true
-        column.containerLayer.backgroundColor = NSColor.controlBackgroundColor.withAlphaComponent(0.56).cgColor
+        column.containerLayer.backgroundColor = themePalette.columnBackground.cgColor
         column.containerLayer.shadowOpacity = 0
         column.containerLayer.shadowRadius = 0
         column.containerLayer.shadowOffset = .zero
@@ -4959,8 +5366,8 @@
         let isSpaceFocused = spaceFocusWindowCount(for: column.column.appGroupIndex) > 0
         let isHovered = column.column.appGroupIndex == effectiveHoveredAppGroupIndex
         column.containerLayer.borderColor = (isSpaceFocused
-            ? NSColor.separatorColor.withAlphaComponent(0.38)
-            : NSColor.separatorColor.withAlphaComponent(0.24)
+            ? themePalette.columnBorder.withAlphaComponent(resolvedTheme == .dark ? 0.34 : 0.38)
+            : themePalette.columnBorder
         ).cgColor
         column.containerLayer.borderWidth = 1
         column.headerLayer.frame = CGRect(
@@ -4972,8 +5379,8 @@
         column.headerLayer.backgroundColor = (isHovered
             ? waterfallAppHoverHeaderFillColor
             : (isSpaceFocused
-                ? NSColor.systemFill.withAlphaComponent(0.10)
-                : NSColor.controlBackgroundColor.withAlphaComponent(0.52))
+                ? themePalette.columnHeaderSpaceFocusedBackground
+                : themePalette.columnHeaderBackground)
         ).cgColor
         column.appNameLayer.frame = CGRect(
             x: WaterfallMetrics.columnHeaderTextInset,
@@ -4981,14 +5388,14 @@
             width: max(1, bounds.width - WaterfallMetrics.columnHeaderTextInset * 2),
             height: 16
         )
-        column.appNameLayer.foregroundColor = NSColor.labelColor.cgColor
+        column.appNameLayer.foregroundColor = themePalette.columnText.cgColor
         column.countLayer.frame = CGRect(
             x: bounds.width - 48,
             y: bounds.height - 24,
             width: 36,
             height: 16
         )
-        column.countLayer.foregroundColor = NSColor.secondaryLabelColor.cgColor
+        column.countLayer.foregroundColor = themePalette.columnSecondaryText.cgColor
 
         let appGroupIndex = column.column.appGroupIndex
         let verticalOffset = clampedWaterfallColumnOffset(
@@ -5065,18 +5472,21 @@
             width: max(1, titleBarFrame.width - 68),
             height: 16
         )
+        card.titleLayer.foregroundColor = themePalette.cardText.cgColor
         card.metaLayer.frame = CGRect(
             x: titleBarFrame.maxX - 38,
             y: titleBarFrame.minY + 6,
             width: 30,
             height: 14
         )
+        card.metaLayer.foregroundColor = themePalette.cardSecondaryText.cgColor
         card.stateLayer.frame = CGRect(
             x: thumbnailFrame.maxX - 86,
             y: thumbnailFrame.minY + 6,
             width: 78,
             height: 14
         )
+        card.stateLayer.foregroundColor = themePalette.cardSecondaryText.cgColor
         layoutCloseButton(
             card.closeButton,
             target: .window(
@@ -5093,6 +5503,11 @@
             width: max(36, min(96, bounds.width * 0.24)),
             height: bounds.height
         )
+        card.shineLayer.colors = [
+            NSColor.white.withAlphaComponent(0.00).cgColor,
+            themePalette.shinePeak.cgColor,
+            NSColor.white.withAlphaComponent(0.00).cgColor
+        ]
     }
 
     private func applyWaterfallCardVisualState(
@@ -5103,14 +5518,14 @@
     ) {
         let isSpaceFocused = isWaterfallCardSpaceFocused(card)
         card.containerLayer.backgroundColor = (selected
-            ? NSColor.windowBackgroundColor.withAlphaComponent(0.94)
+            ? themePalette.cardSelectedBackground
             : hovered
                 ? accentTintedWindowBackground(fraction: 0.09, alpha: 0.95)
                 : appLinked
                     ? accentTintedWindowBackground(fraction: 0.08, alpha: 0.93)
                 : isSpaceFocused
                     ? accentTintedWindowBackground(fraction: 0.10, alpha: 0.94)
-                : NSColor.windowBackgroundColor.withAlphaComponent(0.82)
+                : themePalette.cardBackground
         ).cgColor
         card.containerLayer.borderColor = (selected
             ? NSColor.controlAccentColor.withAlphaComponent(0.52)
@@ -5124,7 +5539,16 @@
         ).cgColor
         card.containerLayer.borderWidth = (selected || hovered || appLinked || isSpaceFocused) ? 1.5 : 1
         card.containerLayer.shadowColor = NSColor.black.cgColor
-        card.containerLayer.shadowOpacity = selected ? 0.24 : hovered ? 0.14 : appLinked ? 0.16 : isSpaceFocused ? 0.20 : 0
+        let darkShadowBoost: Float = resolvedTheme == .dark ? 0.08 : 0
+        card.containerLayer.shadowOpacity = selected
+            ? 0.24 + darkShadowBoost
+            : hovered
+                ? 0.14 + darkShadowBoost
+                : appLinked
+                    ? 0.16 + darkShadowBoost
+                    : isSpaceFocused
+                        ? 0.20 + darkShadowBoost
+                        : 0
         card.containerLayer.shadowRadius = selected ? 22 : hovered ? 17 : appLinked ? 18 : isSpaceFocused ? 24 : 0
         card.containerLayer.shadowOffset = selected
             ? CGSize(width: 0, height: -6)
@@ -5259,9 +5683,16 @@
         )
         layers.backgroundLayer.frame = layers.containerLayer.bounds
         layers.backgroundLayer.path = bubblePath
+        layers.backgroundLayer.fillColor = themePalette.closeFeedbackBackground.withAlphaComponent(resolvedTheme == .dark ? 0.98 : 0.985).cgColor
+        layers.backgroundLayer.strokeColor = themePalette.closeFeedbackBorder.withAlphaComponent(resolvedTheme == .dark ? 0.78 : 1).cgColor
         layers.containerLayer.shadowPath = bubblePath
         layers.titleLayer.string = confirmationTitle(for: request)
         layers.messageLayer.string = confirmationMessage(for: request)
+        layers.titleLayer.foregroundColor = (resolvedTheme == .dark
+            ? NSColor.white.withAlphaComponent(0.92)
+            : NSColor.labelColor
+        ).cgColor
+        layers.messageLayer.foregroundColor = themePalette.closeFeedbackText.cgColor
         layers.titleLayer.frame = CGRect(x: contentFrame.minX + 22, y: height - 48, width: contentFrame.width - 44, height: 22)
         layers.messageLayer.frame = CGRect(x: contentFrame.minX + 22, y: height - 78, width: contentFrame.width - 44, height: 21)
 
@@ -5272,12 +5703,22 @@
         ).cgColor
         layers.checkboxLayer.borderColor = (pendingCloseOptOut
             ? NSColor.controlAccentColor.withAlphaComponent(0.95)
-            : NSColor.separatorColor.withAlphaComponent(0.48)
+            : themePalette.closeFeedbackBorder.withAlphaComponent(resolvedTheme == .dark ? 0.80 : 0.48)
         ).cgColor
         layers.checkboxMarkLayer.string = pendingCloseOptOut ? "✓" : ""
         layers.checkboxMarkLayer.frame = CGRect(x: 0, y: 1, width: 18, height: 16)
+        layers.checkboxLabelLayer.foregroundColor = themePalette.closeFeedbackText.cgColor
         layers.checkboxLabelLayer.frame = CGRect(x: contentFrame.minX + 48, y: 80, width: contentFrame.width - 70, height: 19)
 
+        layers.cancelButtonLayer.backgroundColor = (resolvedTheme == .dark
+            ? NSColor.white.withAlphaComponent(0.10)
+            : NSColor.systemFill.withAlphaComponent(0.16)
+        ).cgColor
+        layers.cancelButtonLayer.borderColor = themePalette.closeFeedbackBorder.withAlphaComponent(resolvedTheme == .dark ? 0.70 : 0.22).cgColor
+        layers.cancelButtonTextLayer.foregroundColor = (resolvedTheme == .dark
+            ? NSColor.white.withAlphaComponent(0.86)
+            : NSColor.labelColor
+        ).cgColor
         layers.cancelButtonLayer.frame = CGRect(x: contentFrame.maxX - 164, y: 22, width: 74, height: 32)
         layers.cancelButtonTextLayer.frame = layers.cancelButtonLayer.bounds.insetBy(dx: 0, dy: 7)
         layers.confirmButtonLayer.frame = CGRect(x: contentFrame.maxX - 78, y: 22, width: 56, height: 32)
@@ -5292,9 +5733,9 @@
         closeFeedbackTextLayer.string = feedback.message
         switch feedback.kind {
         case .progress:
-            closeFeedbackLayer.backgroundColor = NSColor.windowBackgroundColor.withAlphaComponent(0.94).cgColor
-            closeFeedbackLayer.borderColor = NSColor.separatorColor.withAlphaComponent(0.28).cgColor
-            closeFeedbackTextLayer.foregroundColor = NSColor.secondaryLabelColor.withAlphaComponent(0.96).cgColor
+            closeFeedbackLayer.backgroundColor = themePalette.closeFeedbackBackground.cgColor
+            closeFeedbackLayer.borderColor = themePalette.closeFeedbackBorder.cgColor
+            closeFeedbackTextLayer.foregroundColor = themePalette.closeFeedbackText.cgColor
         case .failure:
             closeFeedbackLayer.backgroundColor = NSColor.systemRed.withAlphaComponent(0.10).cgColor
             closeFeedbackLayer.borderColor = NSColor.systemRed.withAlphaComponent(0.32).cgColor
@@ -5682,8 +6123,9 @@
     }
 
     private func accentTintedWindowBackground(fraction: CGFloat, alpha: CGFloat) -> NSColor {
-        let color = NSColor.windowBackgroundColor.blended(withFraction: fraction, of: NSColor.controlAccentColor)
-            ?? NSColor.windowBackgroundColor
+        let baseColor = resolvedTheme == .dark ? themePalette.cardBackground : NSColor.windowBackgroundColor
+        let color = baseColor.blended(withFraction: fraction, of: NSColor.controlAccentColor)
+            ?? baseColor
         return color.withAlphaComponent(alpha)
     }
 
@@ -5735,12 +6177,45 @@
         waterfallViewMode == .horizontalMasonry
     }
 
+    private var resolvedTheme: QuickSwitchResolvedTheme {
+        themePreference == .dark ? .dark : .light
+    }
+
+    private var themePalette: QuickSwitchThemePalette {
+        QuickSwitchThemePalette.palette(for: resolvedTheme)
+    }
+
+    private var darkBackdropAmbientLayers: [CAGradientLayer] {
+        [darkAmbientLeftLayer, darkAmbientCenterLayer, darkAmbientRightLayer]
+    }
+
+    private static func normalizedQuickSwitchTheme(_ theme: ThemePreference) -> ThemePreference {
+        theme == .dark ? .dark : .light
+    }
+
+    private var nextThemePreference: ThemePreference {
+        resolvedTheme == .dark ? .light : .dark
+    }
+
     private var nextWaterfallViewMode: QuickSwitchWaterfallViewMode {
         isHorizontalMasonryMode ? .verticalColumns : .horizontalMasonry
     }
 
     private var viewModeToggleBlueColor: NSColor {
         NSColor(deviceRed: 135.0 / 255.0, green: 200.0 / 255.0, blue: 1, alpha: 1)
+    }
+
+    private var themeToggleIdleBackgroundColor: NSColor {
+        toggleIdleBackgroundColor(hovered: isThemeToggleButtonHovered)
+    }
+
+    private func toggleIdleBackgroundColor(hovered: Bool) -> NSColor {
+        switch resolvedTheme {
+        case .light:
+            return NSColor.windowBackgroundColor.withAlphaComponent(hovered ? 0.76 : 0.58)
+        case .dark:
+            return NSColor(calibratedRed: 24 / 255, green: 34 / 255, blue: 54 / 255, alpha: hovered ? 0.76 : 0.58)
+        }
     }
 
     private var viewModeToggleVisualState: ViewModeToggleVisualState {
@@ -5769,6 +6244,15 @@
             return "切换到纵栏瀑布"
         case .horizontalMasonry:
             return "切换到横栏瀑布"
+        }
+    }
+
+    private var themeToggleAccessibilityLabel: String {
+        switch nextThemePreference {
+        case .dark:
+            return "切换到深色皮肤"
+        case .light, .system:
+            return "切换到浅色皮肤"
         }
     }
 
@@ -5852,7 +6336,7 @@
     }
 
     private var spaceLaneOccupiedColor: NSColor {
-        if effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua {
+        if resolvedTheme == .dark {
             return NSColor(calibratedRed: 10 / 255, green: 132 / 255, blue: 1, alpha: 1)
         }
 
@@ -5860,7 +6344,7 @@
     }
 
     private var spaceLaneLockedFillColor: NSColor {
-        if effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua {
+        if resolvedTheme == .dark {
             return NSColor(calibratedRed: 58 / 255, green: 148 / 255, blue: 1, alpha: 0.86)
         }
 
@@ -5868,9 +6352,9 @@
     }
 
     private func spaceLaneIdleOccupiedGradientColors() -> [NSColor] {
-        if effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua {
-            let blue = NSColor(calibratedRed: 36 / 255, green: 54 / 255, blue: 72 / 255, alpha: 1)
-            let surface = NSColor.windowBackgroundColor.withAlphaComponent(1)
+        if resolvedTheme == .dark {
+            let blue = NSColor(calibratedRed: 18 / 255, green: 42 / 255, blue: 70 / 255, alpha: 0.92)
+            let surface = NSColor(calibratedRed: 22 / 255, green: 34 / 255, blue: 50 / 255, alpha: 0.78)
             return [blue, surface]
         }
 
@@ -5883,7 +6367,7 @@
     private func applySpaceLaneGradientFill(to layer: CALayer, colors: [NSColor]) {
         if let gradientLayer = layer as? CAGradientLayer {
             gradientLayer.colors = colors.map(\.cgColor)
-            gradientLayer.locations = [0, 1]
+            gradientLayer.locations = [0, 1].map(NSNumber.init(value:))
             gradientLayer.startPoint = CGPoint(x: 0.5, y: 1.0)
             gradientLayer.endPoint = CGPoint(x: 0.5, y: 0.0)
         }
@@ -6729,6 +7213,20 @@
         }
     }
 
+    private var darkBackdropLayerCount: Int {
+        darkBackdropAmbientLayers.count + 1
+    }
+
+    private var darkBackdropLayersVisible: Bool {
+        resolvedTheme == .dark
+            && darkBackdropAmbientLayers.allSatisfy { !$0.isHidden }
+            && !darkVignetteLayer.isHidden
+    }
+
+    private func backgroundGradientColorReports() -> [[String: Double]] {
+        gradientColorDictionaries(from: backgroundLayer)
+    }
+
     private func spaceLaneFillKind(for layer: CALayer) -> String {
         if !gradientColorDictionaries(from: layer).isEmpty {
             return "gradient"
diff --git a/C1.source/Sources/Aligner/QuickSwitchSessionController.swift b/C1.source/Sources/Aligner/QuickSwitchSessionController.swift
index 18d84f0..f6b860a 100644
--- a/C1.source/Sources/Aligner/QuickSwitchSessionController.swift
+++ b/C1.source/Sources/Aligner/QuickSwitchSessionController.swift
@@ -20,6 +20,7 @@
     private let systemCriticalWindowDetector: any SystemCriticalWindowDetecting
     private let disableScreenshotRefresh: Bool
     private var waterfallViewMode: QuickSwitchWaterfallViewMode
+    private var theme: ThemePreference
     private var closeConfirmationRequired: Bool
     private let onCloseConfirmationDisabled: (() -> Void)?
     private let debugOverlayWidth: CGFloat?
@@ -87,6 +88,7 @@
     private var lifecycleResidualVisibleOverlayWindows = 0
     var onSnapshotUpdated: (() -> Void)?
     var onToggleWaterfallViewMode: (() -> Void)?
+    var onToggleTheme: (() -> Void)?
 
     private struct PendingCloseVerification {
         let request: QuickSwitchCloseRequest
@@ -123,6 +125,7 @@
         systemCriticalWindowDetector: any SystemCriticalWindowDetecting = CGWindowSystemCriticalWindowDetector(),
         disableScreenshotRefresh: Bool = false,
         waterfallViewMode: QuickSwitchWaterfallViewMode = .verticalColumns,
+        theme: ThemePreference = .light,
         closeConfirmationRequired: Bool = true,
         onCloseConfirmationDisabled: (() -> Void)? = nil,
         debugHoveredAppGroupIndex: Int? = nil,
@@ -139,6 +142,7 @@
         self.systemCriticalWindowDetector = systemCriticalWindowDetector
         self.disableScreenshotRefresh = disableScreenshotRefresh
         self.waterfallViewMode = waterfallViewMode
+        self.theme = theme
         self.closeConfirmationRequired = closeConfirmationRequired
         self.onCloseConfirmationDisabled = onCloseConfirmationDisabled
         self.debugOverlayWidth = debugOverlayWidth
@@ -216,6 +220,9 @@
         view.onToggleWaterfallViewMode = { [weak self] in
             self?.onToggleWaterfallViewMode?()
         }
+        view.onToggleTheme = { [weak self] in
+            self?.onToggleTheme?()
+        }
         view.setSuppressEventInput(!debugMouseSequence.isEmpty || !debugKeySequence.isEmpty)
         view.onRequestClose = { [weak self] request in
             self?.requestClose(request)
@@ -227,6 +234,7 @@
         }
         view.setCloseConfirmationRequired(closeConfirmationRequired)
         view.setWaterfallViewMode(waterfallViewMode)
+        view.setTheme(theme)
         view.apply(viewModel: nil)
         view.beginPerformanceFirstFrameMeasurement()
         coordinator.openQuickSwitch()
@@ -320,6 +328,20 @@
         onSnapshotUpdated?()
     }
 
+    func setTheme(_ theme: ThemePreference) {
+        guard self.theme != theme else { return }
+
+        self.theme = theme
+        DevelopmentDiagnostics.log("quickSwitch.session.themeChanged", [
+            "theme": theme.rawValue,
+            "visible": isVisible,
+            "hasViewModel": currentViewModel != nil
+        ])
+
+        view.setTheme(theme)
+        onSnapshotUpdated?()
+    }
+
     func reportDictionary() -> [String: Any] {
         let spaceCount = currentViewModel?.spaceCount ?? 0
         let appCount = currentViewModel?.appShelf.count ?? 0
diff --git a/C3.tools/round1-main-ui-qa.sh b/C3.tools/round1-main-ui-qa.sh
index 9c29bf2..05fe694 100755
--- a/C3.tools/round1-main-ui-qa.sh
+++ b/C3.tools/round1-main-ui-qa.sh
@@ -115,6 +115,7 @@
 run_step mouse-interaction "$SCRIPT_DIR/round1-mouse-interaction-fixture-qa.sh"
 run_step app-column-alignment "$SCRIPT_DIR/round1-app-column-alignment-fixture-qa.sh"
 run_step horizontal-waterfall "$SCRIPT_DIR/round1-horizontal-waterfall-fixture-qa.sh"
+run_step theme-toggle "$SCRIPT_DIR/round1-theme-toggle-fixture-qa.sh"
 run_step no-quick-switch-residual swift "$SCRIPT_DIR/window-logic-qa.swift" --expect-no-quick-switch
 
 assert_no_current_aligner
@@ -127,5 +128,5 @@
 Covered: trigger, overlay uniqueness, keyboard navigation, candidate filtering,
 screenshots/fallbacks, minimized-window restore/activation, mouse activation,
 multi-page precise activation/close targeting, App column alignment,
-Split View Space Lane rendering, and final no-residual check.
+Split View Space Lane rendering, theme toggle, and final no-residual check.
 EOF
diff --git a/C3.tools/round1-theme-toggle-fixture-qa.sh b/C3.tools/round1-theme-toggle-fixture-qa.sh
new file mode 100755
index 0000000..5a4eccc
--- /dev/null
+++ b/C3.tools/round1-theme-toggle-fixture-qa.sh
@@ -0,0 +1,236 @@
+#!/bin/bash
+# Round01.1 theme toggle fixture QA. It verifies the 0.1.1 Quick Switch
+# light/dark skin toggle, persistence, top-right placement, and dark gradient
+# backdrop evidence without changing the 0.1 interaction model.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+OUTPUT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+# shellcheck source=build-output-paths.sh
+source "$SCRIPT_DIR/build-output-paths.sh"
+APP="$BUILD_CURRENT_APP"
+DOMAIN="com.ar.Aligner"
+THEME_KEY="com.ar.Aligner.preferences.appearance.theme"
+REPORT_WAIT="${ALIGNER_ROUND1_THEME_TOGGLE_REPORT_WAIT:-6.0}"
+REPORT_DEFAULT="$BUILD_REPORT_ROOT/round01-theme-toggle-default-report.json"
+REPORT_DARK="$BUILD_REPORT_ROOT/round01-theme-toggle-dark-report.json"
+REPORT_DARK_REOPEN="$BUILD_REPORT_ROOT/round01-theme-toggle-dark-reopen-report.json"
+REPORT_LIGHT="$BUILD_REPORT_ROOT/round01-theme-toggle-light-report.json"
+OLD_THEME_SET=0
+OLD_THEME=""
+
+fail() {
+  echo "Round01.1 theme toggle QA failed: $*" >&2
+  exit 1
+}
+
+aligner_pids_for_current_app() {
+  ps -axo pid=,args= | while read -r pid command; do
+    case "$command" in
+      "$APP/Contents/MacOS/Aligner"*) echo "$pid" ;;
+    esac
+  done
+}
+
+stop_current_aligner() {
+  for pid in $(aligner_pids_for_current_app); do
+    kill "$pid" 2>/dev/null || true
+  done
+
+  for _ in {1..30}; do
+    [ -z "$(aligner_pids_for_current_app)" ] && return
+    sleep 0.1
+  done
+
+  fail "current Aligner app did not exit before QA"
+}
+
+preserve_user_theme() {
+  if OLD_THEME="$(/usr/bin/defaults read "$DOMAIN" "$THEME_KEY" 2>/dev/null)"; then
+    OLD_THEME_SET=1
+  else
+    OLD_THEME_SET=0
+    OLD_THEME=""
+  fi
+}
+
+restore_user_theme() {
+  if [ "$OLD_THEME_SET" -eq 1 ]; then
+    /usr/bin/defaults write "$DOMAIN" "$THEME_KEY" -string "$OLD_THEME"
+  else
+    /usr/bin/defaults delete "$DOMAIN" "$THEME_KEY" >/dev/null 2>&1 || true
+  fi
+}
+
+wait_for_theme_report() {
+  local report="$1"
+  local expected_theme="$2"
+  local expected_mouse_command="${3:-}"
+
+  /usr/bin/python3 - "$report" "$expected_theme" "$expected_mouse_command" "$REPORT_WAIT" <<'PY'
+import json
+import sys
+import time
+
+path = sys.argv[1]
+expected_theme = sys.argv[2]
+expected_mouse_command = sys.argv[3]
+timeout = float(sys.argv[4])
+deadline = time.monotonic() + timeout
+last_report = None
+
+while time.monotonic() < deadline:
+    try:
+        with open(path, "r", encoding="utf-8") as file:
+            report = json.load(file)
+        last_report = report
+        root = report.get("rootView", {})
+        if (
+            report.get("snapshotLoaded") is True
+            and report.get("quickSwitchVisible") is True
+            and report.get("resolvedQuickSwitchTheme") == expected_theme
+            and root.get("themeResolved") == expected_theme
+            and (not expected_mouse_command or root.get("lastMouseCommand") == expected_mouse_command)
+        ):
+            sys.exit(0)
+    except FileNotFoundError:
+        pass
+    except json.JSONDecodeError:
+        pass
+    time.sleep(0.2)
+
+if last_report is not None:
+    print(json.dumps(last_report, indent=2, ensure_ascii=False), file=sys.stderr)
+print(f"theme report did not reach {expected_theme} within {timeout:.1f}s", file=sys.stderr)
+sys.exit(1)
+PY
+}
+
+assert_theme_report() {
+  local report="$1"
+  local expected_theme="$2"
+  local expected_next_theme="$3"
+  local expected_mouse_command="${4:-}"
+
+  /usr/bin/python3 - "$report" "$expected_theme" "$expected_next_theme" "$expected_mouse_command" <<'PY'
+import json
+import sys
+
+path = sys.argv[1]
+expected_theme = sys.argv[2]
+expected_next_theme = sys.argv[3]
+expected_mouse_command = sys.argv[4]
+
+with open(path, "r", encoding="utf-8") as file:
+    report = json.load(file)
+
+def require(condition, message):
+    if not condition:
+        print(message, file=sys.stderr)
+        print(json.dumps(report, indent=2, ensure_ascii=False), file=sys.stderr)
+        sys.exit(1)
+
+root = report.get("rootView", {})
+theme_frame = root.get("themeToggleButtonFrame", {})
+view_frame = root.get("viewModeToggleButtonFrame", {})
+bounds = root.get("bounds", {})
+gradient_colors = root.get("darkBackdropBackgroundGradientColors", [])
+
+require(report.get("snapshotLoaded") is True, "snapshotLoaded must be true")
+require(report.get("quickSwitchVisible") is True, "Quick Switch must remain visible during theme QA")
+require(report.get("resolvedQuickSwitchTheme") == expected_theme, "app-level resolved Quick Switch theme must match")
+require(root.get("themeCurrentPreference") == expected_theme, "root theme preference must match expected theme")
+require(root.get("themeResolved") == expected_theme, "root resolved theme must match expected theme")
+require(root.get("themeNextPreference") == expected_next_theme, "theme next preference must point to the opposite theme")
+require(root.get("themeToggleButtonVisible") is True, "theme toggle button must be visible")
+require(root.get("themeToggleIconKind") == "halfDisk", "theme toggle must use the approved half-disk icon")
+require(root.get("themeToggleHitSize") == 34, "theme toggle must keep a 34pt hit target")
+require(theme_frame.get("width") == 30 and theme_frame.get("height") == 30, "theme toggle visual size must be 30pt")
+require(view_frame.get("width") == 30 and view_frame.get("height") == 30, "view toggle visual size must remain 30pt")
+require(theme_frame.get("y") == view_frame.get("y"), "theme toggle must align vertically with view toggle")
+require(theme_frame.get("x", 0) < view_frame.get("x", 0), "theme toggle must sit to the left of the view-mode toggle")
+require(view_frame.get("x", 0) + view_frame.get("width", 0) > bounds.get("width", 0) * 0.90, "top-right toggle cluster must remain near the right edge")
+if expected_mouse_command:
+    require(root.get("lastMouseCommand") == expected_mouse_command, "debug mouse command must be recorded")
+
+if expected_theme == "dark":
+    require(root.get("darkBackdropLayersVisible") is True, "dark backdrop ambient layers must be visible in dark theme")
+    require(root.get("darkBackdropLayerCount") == 4, "dark theme must expose three ambient layers plus vignette")
+    require(len(gradient_colors) >= 4, "dark background must expose a multi-stop gradient")
+    reds = {round(color.get("red", 0), 3) for color in gradient_colors}
+    greens = {round(color.get("green", 0), 3) for color in gradient_colors}
+    blues = {round(color.get("blue", 0), 3) for color in gradient_colors}
+    require(len(reds) > 1 and len(greens) > 1 and len(blues) > 1, "dark gradient must not collapse to a single color")
+    first = gradient_colors[0]
+    require(first.get("blue", 0) > first.get("red", 1), "dark gradient must start in a blue-family tone")
+else:
+    require(root.get("darkBackdropLayersVisible") is False, "dark backdrop layers must be hidden in light theme")
+    require(len(gradient_colors) == 2, "light background should keep the existing two-stop baseline gradient")
+
+print(json.dumps({
+    "theme": expected_theme,
+    "nextTheme": root.get("themeNextPreference"),
+    "themeToggleButtonFrame": theme_frame,
+    "viewModeToggleButtonFrame": view_frame,
+    "darkBackdropLayerCount": root.get("darkBackdropLayerCount"),
+    "darkBackdropLayersVisible": root.get("darkBackdropLayersVisible")
+}, indent=2, ensure_ascii=False))
+PY
+}
+
+run_fixture() {
+  local report="$1"
+  shift
+  stop_current_aligner
+  rm -f "$report"
+  "$APP/Contents/MacOS/Aligner" \
+    --round0-skip-permissions \
+    --round01-open-quick-switch \
+    --round01-fixture-app-count=4 \
+    --round01-fixture-windows-per-app=2 \
+    --round01-disable-screenshot-refresh \
+    --round01-quick-switch-report="$report" \
+    --round01-quick-switch-auto-hide-after=1.2 \
+    --round01-quick-switch-quit-after=1.8 \
+    "$@" >/dev/null 2>&1 &
+}
+
+cleanup() {
+  stop_current_aligner || true
+  restore_user_theme
+}
+
+preserve_user_theme
+trap cleanup EXIT
+stop_current_aligner
+
+/usr/bin/defaults delete "$DOMAIN" "$THEME_KEY" >/dev/null 2>&1 || true
+run_fixture "$REPORT_DEFAULT"
+wait_for_theme_report "$REPORT_DEFAULT" "light"
+assert_theme_report "$REPORT_DEFAULT" "light" "dark"
+
+run_fixture "$REPORT_DARK" --round01-debug-mouse-sequence="click-theme-toggle"
+wait_for_theme_report "$REPORT_DARK" "dark" "click-theme-toggle"
+assert_theme_report "$REPORT_DARK" "dark" "light" "click-theme-toggle"
+
+run_fixture "$REPORT_DARK_REOPEN"
+wait_for_theme_report "$REPORT_DARK_REOPEN" "dark"
+assert_theme_report "$REPORT_DARK_REOPEN" "dark" "light"
+
+run_fixture "$REPORT_LIGHT" --round01-debug-mouse-sequence="click-theme-toggle"
+wait_for_theme_report "$REPORT_LIGHT" "light" "click-theme-toggle"
+assert_theme_report "$REPORT_LIGHT" "light" "dark" "click-theme-toggle"
+
+stop_current_aligner
+restore_user_theme
+trap - EXIT
+
+cat <<EOF
+Round01.1 theme toggle QA passed
+Reports:
+- $REPORT_DEFAULT
+- $REPORT_DARK
+- $REPORT_DARK_REOPEN
+- $REPORT_LIGHT
+EOF
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..aa68b51
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,13 @@
+# Changelog
+
+## 0.1.1 / 20260620.0136
+
+- 增加 Quick Switch 浅色 / 深色皮肤切换。
+- 在 Quick Switch 右上角增加半明半暗圆盘切换图标,点击可在两套皮肤间切换。
+- 增加深色皮肤的多层渐变背景、暗色 Space Lane、App Shelf、Waterfall column、窗口卡片和控件配色。
+- 增加主题偏好持久化,重新打开 App 后保持用户上次选择。
+- 增加主题切换 fixture QA,并纳入主 UI 回归入口。
+
+## 0.1.0 / 20260619.2255
+
+- 冻结 Quick Switch MVP2 当前稳定体验,建立 `v0.1.0-build20260619.2255` 回滚基线。

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