Record UI implementation lesson

Ariver

2026-06-18 16ee4576a9ff3c4f91cc30cb4cedbfb41fb3de14

 C1.source/Sources/Aligner/QuickSwitchRootView.swift

@@ -24,6 +24,8 @@
    private lazy var closeConfirmationLayers = makeCloseConfirmationLayers()
    private let closeFeedbackLayer = CALayer()
    private let closeFeedbackTextLayer = CATextLayer()
    private let viewModeToggleButtonLayer = CALayer()
    private let viewModeToggleIconLayer = CALayer()
    private let appIconProvider: any AppIconProviderProtocol = WorkspaceAppIconProvider()
    private let skeletonThumbnailProvider = NativeSkeletonThumbnailProvider(size: NSSize(width: 160, height: 96))
    private var screenshotSourcesByWindowID: [UInt32: ScreenshotResolutionSource] = [:]
@@ -49,15 +51,20 @@
    private var closeConfirmationRequired = true
    private var closeFeedback: CloseFeedback?
    private var closeFeedbackHideTask: Task<Void, Never>?
    private var isViewModeToggleButtonHovered = false
    private var suppressViewModeToggleHoverPreview = false
    private var hoverTarget: HoverTarget = .none
    private var hoverTargetSource: HoverTargetSource = .event
    private var hoveredSpaceLaneID: UInt64?
    private var focusedSpaceID: UInt64?
    private var debugHoveredAppGroupIndex: Int?
    private var waterfallColumns: [WaterfallColumnLayers] = []
    private var waterfallViewMode: QuickSwitchWaterfallViewMode = .verticalColumns
    private var waterfallContentWidth: CGFloat = 0
    private var waterfallScrollOffset: CGFloat = 0
    private var waterfallColumnScrollOffsets: [Int: CGFloat] = [:]
    private var horizontalMasonryContentHeight: CGFloat = 0
    private var horizontalMasonryScrollOffset: CGFloat = 0
    private var currentSelection: QuickSwitchSelection?
    private var columnSelectionHistory: [Int: Int] = [:]
    private var keyboardCommandsApplied: [String] = []
@@ -88,6 +95,7 @@
    var onCommitSelection: ((QuickSwitchSelection, QuickSwitchCommitSource) -> Void)?
    var onSpaceLaneClick: ((UInt64, Int) -> Void)?
    var onBackgroundClick: (() -> Bool)?
    var onToggleWaterfallViewMode: (() -> Void)?
    var onRequestClose: ((QuickSwitchCloseRequest) -> Void)?
    var onCloseConfirmationDisabled: (() -> Void)?

@@ -218,6 +226,7 @@
        let labelLayer: CATextLayer
        let countLayer: CATextLayer
        let appLayer: CATextLayer
        let splitAppLayers: [CATextLayer]
        let windowBlocks: [CALayer]
        let fullscreenMarkerLayer: CALayer?
    }
@@ -232,6 +241,7 @@
        let item: QuickSwitchAppShelfItemViewModel
        let containerLayer: CALayer
        let backgroundLayer: CALayer
        let indexLayer: CATextLayer
        let iconLayer: CALayer
        let labelLayer: CATextLayer
        let badgeLayer: CATextLayer
@@ -290,6 +300,10 @@
        static let normalGap: CGFloat = 16
        static let minGap: CGFloat = 8
        static let maxRows = 2
        static let indexFontSize: CGFloat = 15
        static let compressedIndexFontSize: CGFloat = 13
        static let indexWidth: CGFloat = 16
        static let indexHeight: CGFloat = 18
    }

    private enum RootLayoutMetrics {
@@ -298,6 +312,24 @@
        static let shelfGap: CGFloat = 16
        static let waterfallTopGap: CGFloat = 14
        static let bottomMargin: CGFloat = 34
    }

    private enum ViewModeToggleMetrics {
        static let hitSize: CGFloat = 34
        static let visualSize: CGFloat = 30
        static let cornerRadius: CGFloat = 9
        static let iconInset: CGFloat = 7
        static let glyphLineWidth: CGFloat = 1.65
        static let glyphCornerRadius: CGFloat = 2.1
        static let selectedShadowRadius: CGFloat = 10
        static let idleShadowRadius: CGFloat = 5
    }

    private enum ViewModeToggleVisualState: String {
        case horizontalAvailable = "H1"
        case horizontalSelected = "H2"
        case verticalAvailable = "Z1"
        case verticalSelected = "Z2"
    }

    private enum WaterfallMetrics {
@@ -314,6 +346,16 @@
        static let cardGap: CGFloat = 12
        static let revealPadding: CGFloat = 24
        static let horizontalRevealPadding: CGFloat = 0
    }

    private enum HorizontalMasonryMetrics {
        static let horizontalPadding: CGFloat = 12
        static let verticalPadding: CGFloat = 0
        static let horizontalGap: CGFloat = 16
        static let verticalGap: CGFloat = WaterfallMetrics.cardGap
        static let cardMinWidth: CGFloat = 220
        static let cardMaxWidth: CGFloat = 320
        static let cardHeight: CGFloat = WaterfallMetrics.cardHeight
    }

    private enum WaterfallHorizontalIntent {
@@ -431,6 +473,15 @@
        }

        if shouldScrollWaterfall(for: event) {
            if isHorizontalMasonryMode {
                let currentOffset = horizontalMasonryScrollOffset
                horizontalMasonryScrollOffset = clampedHorizontalMasonryOffset(
                    currentOffset - event.scrollingDeltaY
                )
                needsLayout = true
                return
            }

            if abs(event.scrollingDeltaX) >= abs(event.scrollingDeltaY), waterfallAlignmentScrollable {
                waterfallScrollOffset = clampedWaterfallAlignmentOffset(waterfallScrollOffset - event.scrollingDeltaX)
                needsLayout = true
@@ -457,6 +508,21 @@
    override func mouseMoved(with event: NSEvent) {
        guard debugHoveredAppGroupIndex == nil else { return }

        let toggleHovered = viewModeToggleButtonContains(windowLocation: event.locationInWindow)
        if !toggleHovered {
            suppressViewModeToggleHoverPreview = false
        }
        let shouldShowToggleHoverPreview = toggleHovered && !suppressViewModeToggleHoverPreview
        if isViewModeToggleButtonHovered != shouldShowToggleHoverPreview {
            isViewModeToggleButtonHovered = shouldShowToggleHoverPreview
            needsLayout = true
        }
        if toggleHovered {
            hoveredCloseTarget = nil
            setHoverTarget(.none)
            return
        }

        let closeTarget = closeButtonTarget(at: event.locationInWindow)
        if hoveredCloseTarget != closeTarget {
            hoveredCloseTarget = closeTarget
@@ -467,6 +533,8 @@

    override func mouseExited(with event: NSEvent) {
        guard debugHoveredAppGroupIndex == nil else { return }
        isViewModeToggleButtonHovered = false
        suppressViewModeToggleHoverPreview = false
        hoveredCloseTarget = nil
        setHoverTarget(.none)
    }
@@ -482,6 +550,11 @@
        }

        if handleCloseConfirmationMouseDown(at: event.locationInWindow) {
            return
        }

        if viewModeToggleButtonContains(windowLocation: event.locationInWindow) {
            clickViewModeToggleButton(source: "mouse")
            return
        }

@@ -598,6 +671,17 @@
        needsLayout = true
    }

    func setWaterfallViewMode(_ mode: QuickSwitchWaterfallViewMode) {
        guard waterfallViewMode != mode else { return }

        waterfallViewMode = mode
        waterfallScrollOffset = 0
        waterfallColumnScrollOffsets = [:]
        horizontalMasonryScrollOffset = 0
        horizontalMasonryContentHeight = 0
        needsLayout = true
    }

    func showCloseProgress(for request: QuickSwitchCloseRequest) {
        setCloseFeedback(
            CloseFeedback(
@@ -672,11 +756,38 @@
        apply(viewModel: viewModel, preservingInteractionState: true, animatedProjection: true)
    }

    func hoverNextAppGroupIndex(cycleForward: Bool = true) -> Bool {
        guard !appShelfItems.isEmpty else {
            return false
        }

        let orderedIndexes = appShelfItems.map(\.item.appGroupIndex)
        let sortedIndexes = orderedIndexes

        var currentIndexPosition: Int?
        if let currentHovered = effectiveHoveredAppGroupIndex {
            currentIndexPosition = sortedIndexes.firstIndex(of: currentHovered)
        }

        let nextPosition = currentIndexPosition.map { current in
            if cycleForward {
                (current + 1) % sortedIndexes.count
            } else {
                (current - 1 + sortedIndexes.count) % sortedIndexes.count
            }
        } ?? 0

        let nextAppGroupIndex = sortedIndexes[nextPosition]
        hoverAppGroup(nextAppGroupIndex)
        return true
    }

    private func apply(
        viewModel: QuickSwitchViewModel?,
        preservingInteractionState: Bool,
        animatedProjection: Bool
    ) {
        let preservedWindowThumbnails = preservingInteractionState ? cachedThumbnailsByWindowID() : [:]
        let transitionSnapshot = animatedProjection ? captureProjectionTransitionSnapshot() : nil
        if !animatedProjection {
            resetProjectionTransitionReport()
@@ -715,6 +826,10 @@
            lastSpaceFocusedAppGroupIndex = nil
            lastSpaceLaneClickSpaceID = nil
            lastAppShelfScrollSyncedAppGroupIndex = nil
            waterfallScrollOffset = 0
            waterfallColumnScrollOffsets = [:]
            horizontalMasonryScrollOffset = 0
            horizontalMasonryContentHeight = 0
            focusedSpaceID = nil
            hoveredCloseTarget = nil
            pendingCloseTarget = nil
@@ -733,12 +848,35 @@
        rebuildSpaceLaneSegments()
        rebuildAppShelfItems()
        rebuildWaterfallColumns()

        if preservingInteractionState {
            restoreThumbnailsFromCache(preservedWindowThumbnails)
        }

        needsLayout = true
        ensureCurrentSelectionVisible(horizontalIntent: .alignWithAppShelf(animated: false))
        needsLayout = true
        if animatedProjection, let transitionSnapshot {
            layoutSubtreeIfNeeded()
            applyProjectionTransitionAnimations(from: transitionSnapshot)
        }
    }

    private func cachedThumbnailsByWindowID() -> [UInt32: Any] {
        var snapshots: [UInt32: Any] = [:]

        for card in waterfallCardsByWindowID().values {
            snapshots[card.item.window.id] = card.thumbnailLayer.contents
        }

        return snapshots
    }

    private func restoreThumbnailsFromCache(_ cachedThumbnails: [UInt32: Any]) {
        for card in waterfallCardsByWindowID().values {
            if let thumbnail = cachedThumbnails[card.item.window.id] {
                card.thumbnailLayer.contents = thumbnail
            }
        }
    }

@@ -1021,6 +1159,20 @@
            "activeSpaceFocusID": activeSpaceFocusID ?? NSNull(),
            "spaceFilterLockedSpaceID": currentViewModel?.lockedSpaceID ?? NSNull(),
            "spaceFilterActive": currentViewModel?.lockedSpaceID != nil,
            "viewModeToggleButtonVisible": !viewModeToggleButtonLayer.isHidden,
            "viewModeToggleButtonHovered": isViewModeToggleButtonHovered,
            "viewModeToggleHoverPreviewSuppressed": suppressViewModeToggleHoverPreview,
            "viewModeToggleButtonFrame": dictionary(from: viewModeToggleButtonLayer.frame),
            "viewModeToggleHitSize": Double(ViewModeToggleMetrics.hitSize),
            "viewModeToggleVisualSize": Double(ViewModeToggleMetrics.visualSize),
            "viewModeToggleCurrentMode": waterfallViewMode.rawValue,
            "viewModeToggleTargetMode": nextWaterfallViewMode.rawValue,
            "viewModeToggleIconKind": viewModeToggleIconKind,
            "viewModeToggleVisualState": viewModeToggleVisualState.rawValue,
            "viewModeToggleStandardBlueColor": colorDictionary(from: viewModeToggleBlueColor.cgColor),
            "viewModeToggleGlyphLineWidth": Double(ViewModeToggleMetrics.glyphLineWidth),
            "viewModeToggleAccessibilityLabel": viewModeToggleAccessibilityLabel,
            "settingsButtonVisible": false,
            "spaceFocusAppGroupIndexes": spaceFocusedAppGroupIndexes(),
            "appHoverAssociatedSpaceIDs": appHoverAssociatedSpaceIDs.sorted(),
            "appHoverAssociatedSpaceLabels": appHoverAssociatedSpaceLabels,
@@ -1052,10 +1204,15 @@
            "appShelfMinIconSize": Double(AppShelfMetrics.minIconSize),
            "appShelfItems": appShelfItemReports(),
            "waterfallFrame": dictionary(from: waterfallLayer.frame),
            "waterfallViewMode": waterfallViewMode.rawValue,
            "waterfallContentWidth": Double(waterfallContentWidth),
            "waterfallVisibleWidth": Double(waterfallLayer.bounds.width),
            "waterfallScrollOffset": Double(waterfallScrollOffset),
            "waterfallMaxScrollOffset": Double(waterfallMaxScrollOffset),
            "horizontalMasonryContentHeight": Double(horizontalMasonryContentHeight),
            "horizontalMasonryScrollOffset": Double(horizontalMasonryScrollOffset),
            "horizontalMasonryMaxScrollOffset": Double(horizontalMasonryMaxScrollOffset),
            "horizontalMasonryScrollable": horizontalMasonryMaxScrollOffset > 0,
            "waterfallAlignmentMinScrollOffset": Double(waterfallAlignmentScrollRange.lowerBound),
            "waterfallAlignmentMaxScrollOffset": Double(waterfallAlignmentScrollRange.upperBound),
            "waterfallScrollable": waterfallMaxScrollOffset > 0,
@@ -1167,8 +1324,13 @@
            recordKeyboardCommand("enter")
            commitCurrentSelection()
        case "tab":
            tabIgnoredCount += 1
            recordKeyboardCommand("tabIgnored")
            if isHorizontalMasonryMode {
                recordKeyboardCommand("tab")
                moveSelection(.right)
            } else {
                tabIgnoredCount += 1
                recordKeyboardCommand("tabIgnored")
            }
        default:
            recordKeyboardCommand("unknown:\(command)")
        }
@@ -1253,6 +1415,15 @@
        case "click-background":
            recordMouseCommand("click-background")
            _ = onBackgroundClick?()
        case "hover-view-toggle":
            recordMouseCommand("hover-view-toggle")
            suppressViewModeToggleHoverPreview = false
            isViewModeToggleButtonHovered = true
            hoveredCloseTarget = nil
            setHoverTarget(.none, source: .debug)
        case "click-view-toggle", "click-settings":
            recordMouseCommand("click-view-toggle")
            clickViewModeToggleButton(source: "debug")
        case "hover-card" where parts.count == 3:
            guard let appGroupIndex = Int(parts[1]), let windowIndex = Int(parts[2]) else {
                recordMouseCommand("invalid:\(command)")
@@ -1269,6 +1440,15 @@
            }
            recordMouseCommand("click-card:\(appGroupIndex):\(windowIndex)")
            if let card = waterfallCard(appGroupIndex: appGroupIndex, windowIndex: windowIndex) {
                clickWindowCard(card)
            }
        case "click-card-id" where parts.count == 2:
            guard let windowID = UInt32(parts[1]) else {
                recordMouseCommand("invalid:\(command)")
                return
            }
            recordMouseCommand("click-card-id:\(windowID)")
            if let card = waterfallCard(windowID: windowID) {
                clickWindowCard(card)
            }
        case "hover-card-close" where parts.count == 3:
@@ -1574,6 +1754,11 @@
    }

    private func moveSelection(_ direction: QuickSwitchKeyboardDirection) {
        if isHorizontalMasonryMode {
            moveHorizontalMasonrySelection(direction)
            return
        }

        guard let currentViewModel,
              let snapshot = snapshotForFocus(from: currentViewModel),
              let current = currentSelection ?? currentViewModel.initialSelection,
@@ -1603,6 +1788,113 @@
            "windowID": next.windowID
        ])
        needsLayout = true
    }

    private func moveHorizontalMasonrySelection(_ direction: QuickSwitchKeyboardDirection) {
        guard let current = currentSelection ?? currentViewModel?.initialSelection,
              let next = nextHorizontalMasonrySelection(from: current, direction: direction)
        else {
            DevelopmentDiagnostics.log("quickSwitch.view.moveHorizontalMasonrySelection.blocked", [
                "direction": String(describing: direction),
                "hasSelection": (currentSelection ?? currentViewModel?.initialSelection) != nil
            ])
            return
        }

        columnSelectionHistory[current.appGroupIndex] = current.windowIndex
        currentSelection = next
        columnSelectionHistory[next.appGroupIndex] = next.windowIndex
        ensureCurrentSelectionVisible(horizontalIntent: .alignWithAppShelf(animated: true))
        DevelopmentDiagnostics.log("quickSwitch.view.moveHorizontalMasonrySelection", [
            "direction": String(describing: direction),
            "appGroupIndex": next.appGroupIndex,
            "windowIndex": next.windowIndex,
            "windowID": next.windowID
        ])
        needsLayout = true
    }

    private func nextHorizontalMasonrySelection(
        from current: QuickSwitchSelection,
        direction: QuickSwitchKeyboardDirection
    ) -> QuickSwitchSelection? {
        layoutSubtreeIfNeeded()

        let cards = horizontalMasonryCardsInPlacementOrder()
        guard let currentIndex = cards.firstIndex(where: { $0.item.window.id == current.windowID }) else {
            return cards.first.map(selectionForCard)
        }

        switch direction {
        case .right:
            return selectionForCard(cards[(currentIndex + 1) % cards.count])
        case .left:
            return selectionForCard(cards[(currentIndex - 1 + cards.count) % cards.count])
        case .up:
            return nearestHorizontalMasonrySelection(from: cards[currentIndex], direction: .up)
                ?? selectionForCard(cards.first ?? cards[currentIndex])
        case .down:
            return nearestHorizontalMasonrySelection(from: cards[currentIndex], direction: .down)
                ?? selectionForCard(cards.last ?? cards[currentIndex])
        }
    }

    private func nearestHorizontalMasonrySelection(
        from currentCard: WaterfallCardLayers,
        direction: QuickSwitchKeyboardDirection
    ) -> QuickSwitchSelection? {
        let currentFrame = currentCard.containerLayer.frame
        let candidates = horizontalMasonryCardsInPlacementOrder().filter { card in
            guard card.item.window.id != currentCard.item.window.id else { return false }
            switch direction {
            case .up:
                return card.containerLayer.frame.minY >= currentFrame.maxY - 0.5
            case .down:
                return card.containerLayer.frame.maxY <= currentFrame.minY + 0.5
            case .left, .right:
                return false
            }
        }

        let best = candidates.min { lhs, rhs in
            let lhsFrame = lhs.containerLayer.frame
            let rhsFrame = rhs.containerLayer.frame
            let lhsPrimaryDistance = direction == .up
                ? lhsFrame.minY - currentFrame.maxY
                : currentFrame.minY - lhsFrame.maxY
            let rhsPrimaryDistance = direction == .up
                ? rhsFrame.minY - currentFrame.maxY
                : currentFrame.minY - rhsFrame.maxY
            if abs(lhsPrimaryDistance - rhsPrimaryDistance) > 0.5 {
                return lhsPrimaryDistance < rhsPrimaryDistance
            }

            let lhsHorizontalDistance = abs(lhsFrame.midX - currentFrame.midX)
            let rhsHorizontalDistance = abs(rhsFrame.midX - currentFrame.midX)
            if abs(lhsHorizontalDistance - rhsHorizontalDistance) > 0.5 {
                return lhsHorizontalDistance < rhsHorizontalDistance
            }

            return lhs.item.globalIndex < rhs.item.globalIndex
        }

        return best.map(selectionForCard)
    }

    private func horizontalMasonryCardsInPlacementOrder() -> [WaterfallCardLayers] {
        waterfallColumns
            .sorted { $0.column.appGroupIndex < $1.column.appGroupIndex }
            .flatMap { column in
                column.cards.sorted { $0.item.windowIndex < $1.item.windowIndex }
            }
    }

    private func selectionForCard(_ card: WaterfallCardLayers) -> QuickSwitchSelection {
        QuickSwitchSelection(
            appGroupIndex: card.item.appGroupIndex,
            windowIndex: card.item.windowIndex,
            windowID: card.item.window.id
        )
    }

    private func commitCurrentSelection() {
@@ -1662,9 +1954,24 @@
        _ selection: QuickSwitchSelection,
        horizontalIntent: WaterfallHorizontalIntent = .reveal
    ) {
        if isHorizontalMasonryMode {
            switch horizontalIntent {
            case .reveal:
                ensureHorizontalMasonrySelectionVisible(selection, animated: false)
            case .alignWithAppShelf(let animated):
                ensureHorizontalMasonrySelectionVisible(selection, animated: animated)
            }
            return
        }

        guard
            let column = waterfallColumns.first(where: { $0.column.appGroupIndex == selection.appGroupIndex })
        else {
            return
        }

        if waterfallShouldKeepFilteredColumnsCentered {
            ensureWaterfallCardVisibleVertically(selection)
            return
        }

@@ -1678,6 +1985,11 @@
    }

    private func ensureWaterfallCardVisibleVertically(_ selection: QuickSwitchSelection) {
        guard !isHorizontalMasonryMode else {
            ensureHorizontalMasonrySelectionVisible(selection, animated: false)
            return
        }

        let visibleHeight = max(
            1,
            waterfallLayer.bounds.height
@@ -1705,6 +2017,11 @@
    }

    private func alignWaterfallColumnWithAppShelfIcon(appGroupIndex: Int, animated: Bool) {
        if isHorizontalMasonryMode {
            ensureHorizontalMasonryAppVisible(appGroupIndex, animated: animated)
            return
        }

        guard
            let item = appShelfItems.first(where: { $0.item.appGroupIndex == appGroupIndex }),
            let column = waterfallColumns.first(where: { $0.column.appGroupIndex == appGroupIndex })
@@ -1731,6 +2048,11 @@
    }

    private func ensureWaterfallColumnVisible(_ appGroupIndex: Int) {
        if isHorizontalMasonryMode {
            ensureHorizontalMasonryAppVisible(appGroupIndex, animated: false)
            return
        }

        guard let column = waterfallColumns.first(where: { $0.column.appGroupIndex == appGroupIndex }) else {
            return
        }
@@ -1739,6 +2061,11 @@
    }

    private func ensureWaterfallColumnVisible(_ column: WaterfallColumnLayers) {
        if isHorizontalMasonryMode {
            ensureHorizontalMasonryAppVisible(column.column.appGroupIndex, animated: false)
            return
        }

        waterfallScrollOffset = clampedWaterfallOffset(
            scrollOffset(
                makingVisible: column.containerLayer.frame,
@@ -1751,6 +2078,14 @@
    }

    private var waterfallAlignmentScrollRange: ClosedRange<CGFloat> {
        if isHorizontalMasonryMode {
            return 0...0
        }

        if waterfallShouldKeepFilteredColumnsCentered {
            return 0...0
        }

        var minimumOffset: CGFloat = 0
        var maximumOffset = waterfallMaxScrollOffset

@@ -1775,6 +2110,10 @@
    private func clampedWaterfallAlignmentOffset(_ offset: CGFloat) -> CGFloat {
        let range = waterfallAlignmentScrollRange
        return min(max(range.lowerBound, offset), range.upperBound)
    }

    private var waterfallShouldKeepFilteredColumnsCentered: Bool {
        currentViewModel?.lockedSpaceID != nil && waterfallMaxScrollOffset <= 0.5
    }

    private func setWaterfallScrollOffset(_ offset: CGFloat, animated: Bool) {
@@ -1809,6 +2148,80 @@
        animation.timingFunction = CAMediaTimingFunction(name: WaterfallAlignmentMetrics.animationTimingName)
        animation.isRemovedOnCompletion = true
        waterfallContentLayer.add(animation, forKey: "waterfallColumnAlignment")
    }

    private func ensureHorizontalMasonrySelectionVisible(
        _ selection: QuickSwitchSelection,
        animated: Bool
    ) {
        guard let card = waterfallCard(
            appGroupIndex: selection.appGroupIndex,
            windowIndex: selection.windowIndex
        ) else {
            return
        }

        let visibleFrame = card.containerLayer.frame.offsetBy(
            dx: 0,
            dy: waterfallContentLayer.frame.minY
        )
        let visibleHeight = waterfallLayer.bounds.height
        let padding = WaterfallMetrics.revealPadding
        var nextOffset = horizontalMasonryScrollOffset

        if visibleFrame.maxY > visibleHeight - padding {
            nextOffset -= visibleFrame.maxY - (visibleHeight - padding)
        } else if visibleFrame.minY < padding {
            nextOffset += padding - visibleFrame.minY
        }

        setHorizontalMasonryScrollOffset(nextOffset, animated: animated)
    }

    private func ensureHorizontalMasonryAppVisible(_ appGroupIndex: Int, animated: Bool) {
        guard let firstCard = waterfallColumns
            .first(where: { $0.column.appGroupIndex == appGroupIndex })?
            .cards
            .sorted(by: { $0.item.windowIndex < $1.item.windowIndex })
            .first
        else {
            return
        }

        let cardTopDistance = horizontalMasonryContentHeight - firstCard.containerLayer.frame.maxY
        setHorizontalMasonryScrollOffset(
            cardTopDistance - WaterfallMetrics.revealPadding,
            animated: animated
        )
    }

    private func setHorizontalMasonryScrollOffset(_ offset: CGFloat, animated: Bool) {
        let nextOffset = clampedHorizontalMasonryOffset(offset)
        let previousPositionY = waterfallContentLayer.presentation()?.position.y
            ?? waterfallContentLayer.position.y

        horizontalMasonryScrollOffset = nextOffset
        CATransaction.begin()
        CATransaction.setDisableActions(true)
        waterfallContentLayer.frame = horizontalMasonryContentFrame()
        CATransaction.commit()

        let nextPositionY = waterfallContentLayer.position.y
        guard animated,
              !NSWorkspace.shared.accessibilityDisplayShouldReduceMotion,
              abs(previousPositionY - nextPositionY) > 0.5
        else {
            waterfallContentLayer.removeAnimation(forKey: "horizontalMasonryAlignment")
            return
        }

        let animation = CABasicAnimation(keyPath: "position.y")
        animation.fromValue = previousPositionY
        animation.toValue = nextPositionY
        animation.duration = WaterfallAlignmentMetrics.animationDuration
        animation.timingFunction = CAMediaTimingFunction(name: WaterfallAlignmentMetrics.animationTimingName)
        animation.isRemovedOnCompletion = true
        waterfallContentLayer.add(animation, forKey: "horizontalMasonryAlignment")
    }

    private func scrollOffset(
@@ -1962,6 +2375,16 @@
        closeFeedbackTextLayer.truncationMode = .end
        closeFeedbackLayer.addSublayer(closeFeedbackTextLayer)
        glassLayer.addSublayer(closeFeedbackLayer)

        viewModeToggleButtonLayer.cornerRadius = 10
        viewModeToggleButtonLayer.masksToBounds = false
        viewModeToggleButtonLayer.borderWidth = 1
        viewModeToggleButtonLayer.shadowColor = NSColor.black.cgColor
        viewModeToggleButtonLayer.shadowOffset = CGSize(width: 0, height: -2)
        viewModeToggleButtonLayer.zPosition = 170
        viewModeToggleIconLayer.contentsScale = backingScaleFactor
        viewModeToggleButtonLayer.addSublayer(viewModeToggleIconLayer)
        glassLayer.addSublayer(viewModeToggleButtonLayer)
    }

    private func rebuildAppShelfItems() {
@@ -1969,7 +2392,7 @@
            item.containerLayer.removeFromSuperlayer()
        }

        appShelfItems = (currentViewModel?.appShelf ?? []).map { item in
        appShelfItems = (currentViewModel?.appShelf ?? []).enumerated().map { ordinal, item in
            let container = CALayer()
            container.name = item.app.name

@@ -1985,6 +2408,18 @@
            icon.contents = appIconProvider.icon(for: item.app)
            icon.cornerRadius = 12
            icon.masksToBounds = false

            let indexLabel = makeTextLayer(
                string: appShelfIndexText(forOrdinal: ordinal),
                fontSize: AppShelfMetrics.indexFontSize,
                weight: .regular,
                color: appShelfIndexColor,
                alignment: .center
            )
            indexLabel.font = appShelfIndexFont(size: AppShelfMetrics.indexFontSize)
            indexLabel.fontSize = AppShelfMetrics.indexFontSize
            indexLabel.truncationMode = .end
            indexLabel.zPosition = 14

            let label = makeTextLayer(
                string: item.app.name,
@@ -2010,6 +2445,7 @@
            let closeButton = makeCloseButtonLayers()

            container.addSublayer(background)
            container.addSublayer(indexLabel)
            container.addSublayer(icon)
            container.addSublayer(label)
            container.addSublayer(badge)
@@ -2020,6 +2456,7 @@
                item: item,
                containerLayer: container,
                backgroundLayer: background,
                indexLayer: indexLabel,
                iconLayer: icon,
                labelLayer: label,
                badgeLayer: badge,
@@ -2212,6 +2649,15 @@
                    color: space.type == .fullscreen ? .labelColor : .secondaryLabelColor,
                    alignment: space.type == .fullscreen ? .center : .left
                )
                let splitAppLayers = splitViewAppNames(for: space).map { name in
                    makeTextLayer(
                        string: name,
                        fontSize: 12,
                        weight: .medium,
                        color: .labelColor,
                        alignment: .center
                    )
                }
                let windowBlocks = space.type == .fullscreen
                    ? []
                    : makeWindowBlocks(count: min(space.windowCount, 5), space: space)
@@ -2222,6 +2668,9 @@
                container.addSublayer(appLayer)
                if let fullscreenMarkerLayer {
                    container.addSublayer(fullscreenMarkerLayer)
                }
                for splitAppLayer in splitAppLayers {
                    container.addSublayer(splitAppLayer)
                }
                for block in windowBlocks {
                    container.addSublayer(block)
@@ -2234,6 +2683,7 @@
                    labelLayer: labelLayer,
                    countLayer: countLayer,
                    appLayer: appLayer,
                    splitAppLayers: splitAppLayers,
                    windowBlocks: windowBlocks,
                    fullscreenMarkerLayer: fullscreenMarkerLayer
                )
@@ -2299,8 +2749,160 @@
        layoutWaterfallColumns()
        layoutCloseConfirmation()
        layoutCloseFeedback()
        layoutViewModeToggleButton()

        CATransaction.commit()
    }

    private func layoutViewModeToggleButton() {
        let size = ViewModeToggleMetrics.visualSize
        let topMargin = topSafeAreaInset + RootLayoutMetrics.topContentMargin
        let x = max(
            RootLayoutMetrics.horizontalMargin,
            glassLayer.bounds.width - RootLayoutMetrics.horizontalMargin - size
        )
        let y = max(
            RootLayoutMetrics.bottomMargin,
            glassLayer.bounds.height - topMargin - size
        )
        viewModeToggleButtonLayer.frame = CGRect(x: x, y: y, width: size, height: size)
        viewModeToggleButtonLayer.cornerRadius = ViewModeToggleMetrics.cornerRadius
        let visualState = viewModeToggleVisualState
        let isSelectedState = viewModeToggleVisualStateIsSelected(visualState)
        viewModeToggleButtonLayer.backgroundColor = (isSelectedState
            ? viewModeToggleBlueColor
            : NSColor.windowBackgroundColor.withAlphaComponent(isViewModeToggleButtonHovered ? 0.76 : 0.58)
        ).cgColor
        viewModeToggleButtonLayer.borderColor = (isSelectedState
            ? viewModeToggleBlueColor.withAlphaComponent(0.96)
            : viewModeToggleBlueColor.withAlphaComponent(isViewModeToggleButtonHovered ? 0.72 : 0.34)
        ).cgColor
        viewModeToggleButtonLayer.shadowOpacity = isSelectedState ? 0.16 : (isViewModeToggleButtonHovered ? 0.11 : 0.06)
        viewModeToggleButtonLayer.shadowRadius = isSelectedState
            ? ViewModeToggleMetrics.selectedShadowRadius
            : ViewModeToggleMetrics.idleShadowRadius
        viewModeToggleIconLayer.contentsScale = backingScaleFactor
        let iconInset = ViewModeToggleMetrics.iconInset
        viewModeToggleIconLayer.frame = viewModeToggleButtonLayer.bounds.insetBy(dx: iconInset, dy: iconInset)
        layoutViewModeToggleIcon()
    }

    private func layoutViewModeToggleIcon() {
        CATransaction.begin()
        CATransaction.setDisableActions(true)
        viewModeToggleIconLayer.sublayers?.forEach { $0.removeFromSuperlayer() }

        let bounds = viewModeToggleIconLayer.bounds
        guard bounds.width > 0, bounds.height > 0 else {
            CATransaction.commit()
            return
        }

        let visualState = viewModeToggleVisualState
        let isSelectedState = viewModeToggleVisualStateIsSelected(visualState)
        let strokeColor = isSelectedState
            ? NSColor.white.withAlphaComponent(0.98)
            : viewModeToggleBlueColor.withAlphaComponent(0.96)
        let fillColor = isSelectedState
            ? NSColor.white.withAlphaComponent(0.22)
            : viewModeToggleBlueColor.withAlphaComponent(0.06)
        let glyphRect = centeredSquare(in: bounds)

        switch visualState {
        case .verticalAvailable, .verticalSelected:
            addVerticalColumnsToggleGlyph(
                in: glyphRect,
                strokeColor: strokeColor,
                fillColor: fillColor
            )
        case .horizontalAvailable, .horizontalSelected:
            addHorizontalMasonryToggleGlyph(
                in: glyphRect,
                strokeColor: strokeColor,
                fillColor: fillColor
            )
        }

        CATransaction.commit()
    }

    private func addVerticalColumnsToggleGlyph(
        in rect: CGRect,
        strokeColor: NSColor,
        fillColor: NSColor
    ) {
        let columnWidth = rect.width * 0.22
        let gap = (rect.width - columnWidth * 3) / 2
        for index in 0..<3 {
            let x = rect.minX + CGFloat(index) * (columnWidth + gap)
            let columnRect = CGRect(x: x, y: rect.minY, width: columnWidth, height: rect.height)
            addViewModeToggleRoundedRect(
                columnRect,
                cornerRadius: ViewModeToggleMetrics.glyphCornerRadius,
                strokeColor: strokeColor,
                fillColor: fillColor,
                lineWidth: ViewModeToggleMetrics.glyphLineWidth
            )
        }
    }

    private func addHorizontalMasonryToggleGlyph(
        in rect: CGRect,
        strokeColor: NSColor,
        fillColor: NSColor
    ) {
        let cellSize = rect.width * 0.38
        let gap = rect.width - cellSize * 2
        for row in 0..<2 {
            for column in 0..<2 {
                let cellRect = CGRect(
                    x: rect.minX + CGFloat(column) * (cellSize + gap),
                    y: rect.minY + CGFloat(row) * (cellSize + gap),
                    width: cellSize,
                    height: cellSize
                )
                addViewModeToggleRoundedRect(
                    cellRect,
                    cornerRadius: ViewModeToggleMetrics.glyphCornerRadius,
                    strokeColor: strokeColor,
                    fillColor: fillColor,
                    lineWidth: ViewModeToggleMetrics.glyphLineWidth
                )
            }
        }
    }

    private func addViewModeToggleRoundedRect(
        _ rect: CGRect,
        cornerRadius: CGFloat,
        strokeColor: NSColor,
        fillColor: NSColor,
        lineWidth: CGFloat
    ) {
        let layer = CAShapeLayer()
        layer.contentsScale = backingScaleFactor
        layer.frame = viewModeToggleIconLayer.bounds
        layer.path = CGPath(
            roundedRect: rect,
            cornerWidth: cornerRadius,
            cornerHeight: cornerRadius,
            transform: nil
        )
        layer.fillColor = fillColor.cgColor
        layer.strokeColor = strokeColor.cgColor
        layer.lineWidth = lineWidth
        layer.lineJoin = .round
        viewModeToggleIconLayer.addSublayer(layer)
    }

    private func centeredSquare(in rect: CGRect) -> CGRect {
        let side = min(rect.width, rect.height)
        return CGRect(
            x: rect.midX - side / 2,
            y: rect.midY - side / 2,
            width: side,
            height: side
        )
    }

    private var topSafeAreaInset: CGFloat {
@@ -2488,10 +3090,10 @@
        let isActive = isHovered || isFocused || isLocked
        let isAssociated = (isAppAssociated || isWindowAssociated) && !isActive

        segment.containerLayer.borderWidth = isLocked
            ? 6
            : (hasWindows || isCurrent || isActive || isAssociated) ? 1.5 : 1
        segment.containerLayer.borderColor = (isActive
        segment.containerLayer.borderWidth = (hasWindows || isCurrent || isActive || isAssociated) ? 1.5 : 1
        segment.containerLayer.borderColor = (isLocked
            ? NSColor.white.withAlphaComponent(0.86)
            : isActive
            ? spaceLaneOccupiedColor.withAlphaComponent(isLocked ? 0.92 : 0.62)
            : isAssociated
                ? spaceLaneOccupiedColor.withAlphaComponent(0.50)
@@ -2501,7 +3103,12 @@
                    ? NSColor.labelColor.withAlphaComponent(0.34)
                : NSColor.separatorColor.withAlphaComponent(0.34)
        ).cgColor
        if !hasWindows {
        if isLocked {
            applySpaceLaneSolidFill(
                to: segment.containerLayer,
                color: spaceLaneLockedFillColor
            )
        } else if !hasWindows {
            applySpaceLaneSolidFill(to: segment.containerLayer, color: .clear)
        } else if isActive {
            applySpaceLaneSolidFill(
@@ -2536,7 +3143,7 @@
        segment.containerLayer.transform = (isActive || isAssociated)
            ? CATransform3DMakeScale(isActive ? 1.03 : 1.015, isActive ? 1.03 : 1.015, 1)
            : CATransform3DIdentity
        segment.containerLayer.shadowPath = hasWindows
        segment.containerLayer.shadowPath = (hasWindows || isLocked)
            ? CGPath(
                roundedRect: segment.containerLayer.bounds,
                cornerWidth: segment.containerLayer.cornerRadius,
@@ -2544,6 +3151,37 @@
                transform: nil
            )
            : nil

        applySpaceLaneContentVisualState(segment, isLocked: isLocked)
    }

    private func applySpaceLaneContentVisualState(_ segment: SpaceLaneSegmentLayers, isLocked: Bool) {
        let primaryTextColor: NSColor = isLocked ? .white : .labelColor
        let secondaryTextColor: NSColor = isLocked
            ? .white
            : .secondaryLabelColor

        segment.labelLayer.foregroundColor = primaryTextColor.cgColor
        segment.countLayer.foregroundColor = (isLocked ? NSColor.white : .secondaryLabelColor).cgColor
        segment.appLayer.foregroundColor = (segment.space.type == .fullscreen
            ? primaryTextColor
            : secondaryTextColor
        ).cgColor
        for splitAppLayer in segment.splitAppLayers {
            splitAppLayer.foregroundColor = primaryTextColor.cgColor
        }

        for block in segment.windowBlocks {
            block.backgroundColor = (isLocked
                ? NSColor.white
                : spaceLaneOccupiedColor.withAlphaComponent(segment.space.isCurrent ? 0.72 : 0.58)
            ).cgColor
        }

        (segment.fullscreenMarkerLayer as? CAShapeLayer)?.strokeColor = (isLocked
            ? NSColor.white
            : NSColor.secondaryLabelColor.withAlphaComponent(segment.space.isCurrent ? 0.42 : 0.28)
        ).cgColor
    }

    private func shouldScrollSpaceLane(for event: NSEvent) -> Bool {
@@ -2616,6 +3254,33 @@
        spaceLaneSegments.first { $0.space.id == spaceID }
    }

    private func viewModeToggleButtonContains(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 viewModeToggleButtonLayer.frame
            .insetBy(dx: -hitOutset, dy: -hitOutset)
            .contains(locationInGlass)
    }

    private func clickViewModeToggleButton(source: String) {
        DevelopmentDiagnostics.log("quickSwitch.view.clickWaterfallViewModeToggle", [
            "source": source,
            "currentMode": waterfallViewMode.rawValue,
            "targetMode": nextWaterfallViewMode.rawValue
        ])
        lastMouseCommand = "click-view-toggle"
        if !mouseCommandsApplied.contains("click-view-toggle") {
            mouseCommandsApplied.append("click-view-toggle")
        }
        isViewModeToggleButtonHovered = false
        suppressViewModeToggleHoverPreview = true
        onToggleWaterfallViewMode?()
    }

    private func appShelfItem(at windowLocation: CGPoint) -> AppShelfItemLayers? {
        let locationInView = convert(windowLocation, from: nil)
        let locationInShelfContent = CGPoint(
@@ -2655,23 +3320,61 @@
            .first(where: { $0.item.windowIndex == windowIndex })
    }

    private func waterfallCard(windowID: UInt32) -> WaterfallCardLayers? {
        waterfallColumns
            .lazy
            .flatMap(\.cards)
            .first(where: { $0.item.window.id == windowID })
    }

    private func layoutSpaceLaneSegmentContents(_ segment: SpaceLaneSegmentLayers) {
        let bounds = segment.containerLayer.bounds
        let splitAppNames = splitViewAppNames(for: segment.space)
        let isSplitView = splitAppNames.count >= 2
        segment.labelLayer.frame = CGRect(x: 10, y: bounds.height - 29, width: max(1, bounds.width - 48), height: 20)
        segment.countLayer.frame = CGRect(x: bounds.width - 34, y: bounds.height - 29, width: 24, height: 20)
        segment.countLayer.string = isSplitView ? "" : "\(segment.space.windowCount)"
        segment.countLayer.isHidden = isSplitView
        if segment.space.type == .fullscreen {
            let markerFrame = fullscreenMarkerFrame(in: bounds)
            segment.appLayer.frame = CGRect(
                x: 8,
                y: markerFrame.midY - 8.5,
                width: max(1, bounds.width - 16),
                height: 17
            )
            segment.appLayer.isHidden = isSplitView
            if isSplitView {
                let labelY = markerFrame.midY - 8.5
                let halfWidth = markerFrame.width / 2
                for (index, splitAppLayer) in segment.splitAppLayers.enumerated() {
                    let x = markerFrame.minX + CGFloat(index) * halfWidth
                    splitAppLayer.isHidden = false
                    splitAppLayer.frame = CGRect(
                        x: x + 4,
                        y: labelY,
                        width: max(1, halfWidth - 8),
                        height: 17
                    )
                }
            } else {
                segment.appLayer.frame = CGRect(
                    x: 8,
                    y: markerFrame.midY - 8.5,
                    width: max(1, bounds.width - 16),
                    height: 17
                )
                for splitAppLayer in segment.splitAppLayers {
                    splitAppLayer.isHidden = true
                }
            }
        } else {
            segment.appLayer.isHidden = false
            segment.appLayer.frame = CGRect(x: 10, y: 9, width: max(1, bounds.width - 20), height: 17)
            for splitAppLayer in segment.splitAppLayers {
                splitAppLayer.isHidden = true
            }
        }
        if let fullscreenMarkerLayer = segment.fullscreenMarkerLayer {
            layoutFullscreenMarkerLayer(fullscreenMarkerLayer, in: bounds)
            layoutFullscreenMarkerLayer(
                fullscreenMarkerLayer,
                in: bounds,
                isSplitView: isSplitView
            )
        }

        let blockGap: CGFloat = 5
@@ -2787,6 +3490,13 @@
            )
            : nil
        item.iconLayer.frame = CGRect(x: iconX, y: iconY, width: visualIconSize, height: visualIconSize)
        layoutAppShelfIndexLayer(
            item.indexLayer,
            iconFrame: item.iconLayer.frame,
            iconSize: visualIconSize,
            itemBounds: bounds,
            highlighted: showsSelectedVisual || isHovered
        )
        item.labelLayer.contentsScale = backingScaleFactor
        item.labelLayer.frame = CGRect(x: 0, y: 0, width: bounds.width, height: 14)
        item.badgeLayer.string = badgeText
@@ -2812,6 +3522,67 @@
        )
        item.selectedIndicatorLayer.frame = .zero
        item.selectedIndicatorLayer.backgroundColor = NSColor.clear.cgColor
    }

    private var appShelfIndexColor: NSColor {
        NSColor.labelColor.withAlphaComponent(0.34)
    }

    private var appShelfIndexHighlightedColor: NSColor {
        NSColor.labelColor.withAlphaComponent(0.42)
    }

    private func appShelfIndexFont(size: CGFloat) -> NSFont {
        for fontName in ["Bradley Hand ITC", "Noteworthy-Light", "Marker Felt", "Snell Roundhand"] {
            if let font = NSFont(name: fontName, size: size) {
                return font
            }
        }

        return NSFont.monospacedSystemFont(ofSize: size, weight: .regular)
    }

    private func appShelfIndexText(forOrdinal ordinal: Int) -> String {
        let symbols = Array("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ")
        guard ordinal >= 0 else { return "" }
        if ordinal < symbols.count {
            return String(symbols[ordinal])
        }

        let overflowIndex = ordinal - symbols.count
        let prefix = symbols[10 + (overflowIndex / 26) % 26]
        let suffix = symbols[10 + overflowIndex % 26]
        return "\(prefix)\(suffix)"
    }

    private func layoutAppShelfIndexLayer(
        _ layer: CATextLayer,
        iconFrame: CGRect,
        iconSize: CGFloat,
        itemBounds: CGRect,
        highlighted: Bool
    ) {
        let fontSize = iconSize <= AppShelfMetrics.minIconSize + 1
            ? AppShelfMetrics.compressedIndexFontSize
            : AppShelfMetrics.indexFontSize
        layer.contentsScale = backingScaleFactor
        layer.font = appShelfIndexFont(size: fontSize)
        layer.fontSize = fontSize
        layer.foregroundColor = (highlighted ? appShelfIndexHighlightedColor : appShelfIndexColor).cgColor
        layer.opacity = iconSize <= AppShelfMetrics.minIconSize + 1 ? 0.72 : 0.82

        let indexWidth = AppShelfMetrics.indexWidth
        let indexHeight = AppShelfMetrics.indexHeight
        let preferredX = iconFrame.minX - indexWidth - 1
        let clampedX = max(-6, min(itemBounds.width - indexWidth, preferredX))
        let preferredY = iconFrame.maxY - indexHeight + 4
        let clampedY = max(0, min(itemBounds.height - indexHeight, preferredY))
        layer.frame = CGRect(
            x: clampedX,
            y: clampedY,
            width: indexWidth,
            height: indexHeight
        )
    }

    private func appShelfRows() -> [[AppShelfItemLayers]] {
@@ -2861,6 +3632,14 @@
                .cards
                .compactMap(\.item.primarySpaceID) ?? []
        )
    }

    private var appIconHoverLinkedAppGroupIndex: Int? {
        if let debugHoveredAppGroupIndex {
            return debugHoveredAppGroupIndex
        }
        guard case .app(let appGroupIndex) = hoverTarget else { return nil }
        return appGroupIndex
    }

    private var appHoverAssociatedSpaceLabels: [String] {
@@ -2927,6 +3706,10 @@
              let column = waterfallColumns.first(where: { $0.column.appGroupIndex == appGroupIndex })
        else {
            return "none"
        }

        guard !isHorizontalMasonryMode else {
            return "visible"
        }

        let visibleMinX = waterfallScrollOffset
@@ -3011,17 +3794,24 @@
    }

    private func layoutWaterfallColumns() {
        if isHorizontalMasonryMode {
            layoutHorizontalMasonryWaterfall()
            return
        }

        guard !waterfallColumns.isEmpty else {
            waterfallContentWidth = waterfallLayer.bounds.width
            waterfallScrollOffset = 0
            horizontalMasonryContentHeight = waterfallLayer.bounds.height
            horizontalMasonryScrollOffset = 0
            waterfallContentLayer.frame = waterfallLayer.bounds
            return
        }

        let columnWidth = waterfallColumnWidth()
        let totalWidth = WaterfallMetrics.contentHorizontalPadding * 2
            + CGFloat(waterfallColumns.count) * columnWidth
        let columnsWidth = CGFloat(waterfallColumns.count) * columnWidth
            + CGFloat(max(0, waterfallColumns.count - 1)) * WaterfallMetrics.gap
        let totalWidth = WaterfallMetrics.contentHorizontalPadding * 2 + columnsWidth
        waterfallContentWidth = max(waterfallLayer.bounds.width, totalWidth)
        waterfallScrollOffset = clampedWaterfallAlignmentOffset(waterfallScrollOffset)
        waterfallContentLayer.frame = CGRect(
@@ -3031,7 +3821,7 @@
            height: waterfallLayer.bounds.height
        )

        var x = WaterfallMetrics.contentHorizontalPadding
        var x = waterfallColumnStartX(columnsWidth: columnsWidth)
        for column in waterfallColumns {
            column.containerLayer.frame = CGRect(
                x: x,
@@ -3044,7 +3834,174 @@
        }
    }

    private func layoutHorizontalMasonryWaterfall() {
        guard !waterfallColumns.isEmpty else {
            waterfallContentWidth = waterfallLayer.bounds.width
            waterfallScrollOffset = 0
            horizontalMasonryContentHeight = waterfallLayer.bounds.height
            horizontalMasonryScrollOffset = 0
            waterfallContentLayer.frame = waterfallLayer.bounds
            return
        }

        let layout = horizontalMasonryLayout()
        waterfallContentWidth = waterfallLayer.bounds.width
        waterfallScrollOffset = 0
        horizontalMasonryContentHeight = layout.contentHeight
        horizontalMasonryScrollOffset = clampedHorizontalMasonryOffset(horizontalMasonryScrollOffset)
        waterfallContentLayer.frame = horizontalMasonryContentFrame()

        for column in waterfallColumns {
            column.containerLayer.frame = CGRect(
                x: 0,
                y: 0,
                width: waterfallContentWidth,
                height: horizontalMasonryContentHeight
            )
            column.containerLayer.masksToBounds = false
            column.containerLayer.backgroundColor = NSColor.clear.cgColor
            column.containerLayer.borderColor = NSColor.clear.cgColor
            column.containerLayer.borderWidth = 0
            column.containerLayer.shadowOpacity = 0
            column.containerLayer.shadowRadius = 0
            column.containerLayer.shadowOffset = .zero
            column.headerLayer.isHidden = true
            column.appNameLayer.isHidden = true
            column.countLayer.isHidden = true

            for card in column.cards {
                if let frame = layout.cardFramesByWindowID[card.item.window.id] {
                    card.containerLayer.frame = frame
                } else {
                    card.containerLayer.frame = .zero
                }
                layoutWaterfallCard(card)
            }
        }
    }

    private struct HorizontalMasonryLayout {
        let contentHeight: CGFloat
        let cardFramesByWindowID: [UInt32: CGRect]
    }

    private func horizontalMasonryLayout() -> HorizontalMasonryLayout {
        let cards = horizontalMasonryCardsInPlacementOrder()
        guard !cards.isEmpty else {
            return HorizontalMasonryLayout(
                contentHeight: waterfallLayer.bounds.height,
                cardFramesByWindowID: [:]
            )
        }

        let viewportWidth = max(1, waterfallLayer.bounds.width)
        let availableWidth = max(
            HorizontalMasonryMetrics.cardMinWidth,
            viewportWidth - HorizontalMasonryMetrics.horizontalPadding * 2
        )
        let maximumLaneCount = max(
            1,
            Int(
                floor(
                    (availableWidth + HorizontalMasonryMetrics.horizontalGap)
                        / (HorizontalMasonryMetrics.cardMinWidth + HorizontalMasonryMetrics.horizontalGap)
                )
            )
        )
        let laneCount = min(maximumLaneCount, max(1, cards.count))
        let fittingWidth = (
            availableWidth - CGFloat(max(0, laneCount - 1)) * HorizontalMasonryMetrics.horizontalGap
        ) / CGFloat(laneCount)
        let cardWidth = floor(
            min(
                HorizontalMasonryMetrics.cardMaxWidth,
                max(HorizontalMasonryMetrics.cardMinWidth, fittingWidth)
            )
        )
        let usedWidth = CGFloat(laneCount) * cardWidth
            + CGFloat(max(0, laneCount - 1)) * HorizontalMasonryMetrics.horizontalGap
        let startX = max(
            HorizontalMasonryMetrics.horizontalPadding,
            (viewportWidth - usedWidth) / 2
        )

        var laneHeights = Array(repeating: CGFloat(0), count: laneCount)
        var plannedFrames: [(windowID: UInt32, x: CGFloat, top: CGFloat, width: CGFloat, height: CGFloat)] = []

        for card in cards {
            let laneIndex = laneHeights.enumerated().min { lhs, rhs in
                if abs(lhs.element - rhs.element) > 0.5 {
                    return lhs.element < rhs.element
                }
                return lhs.offset < rhs.offset
            }?.offset ?? 0
            let cardHeight = HorizontalMasonryMetrics.cardHeight
            let x = startX + CGFloat(laneIndex) * (cardWidth + HorizontalMasonryMetrics.horizontalGap)
            let top = HorizontalMasonryMetrics.verticalPadding + laneHeights[laneIndex]
            plannedFrames.append((
                windowID: card.item.window.id,
                x: x,
                top: top,
                width: cardWidth,
                height: cardHeight
            ))
            laneHeights[laneIndex] += cardHeight + HorizontalMasonryMetrics.verticalGap
        }

        let tallestLane = laneHeights.max().map {
            max(0, $0 - HorizontalMasonryMetrics.verticalGap)
        } ?? 0
        let contentHeight = max(
            waterfallLayer.bounds.height,
            HorizontalMasonryMetrics.verticalPadding * 2 + tallestLane
        )
        let frames = Dictionary(
            uniqueKeysWithValues: plannedFrames.map { planned in
                (
                    planned.windowID,
                    CGRect(
                        x: planned.x,
                        y: contentHeight - planned.top - planned.height,
                        width: planned.width,
                        height: planned.height
                    )
                )
            }
        )

        return HorizontalMasonryLayout(contentHeight: contentHeight, cardFramesByWindowID: frames)
    }

    private func horizontalMasonryContentFrame() -> CGRect {
        let contentHeight = max(waterfallLayer.bounds.height, horizontalMasonryContentHeight)
        return CGRect(
            x: 0,
            y: waterfallLayer.bounds.height - contentHeight + horizontalMasonryScrollOffset,
            width: waterfallLayer.bounds.width,
            height: contentHeight
        )
    }

    private func waterfallColumnStartX(columnsWidth: CGFloat) -> CGFloat {
        guard currentViewModel?.lockedSpaceID != nil else {
            return WaterfallMetrics.contentHorizontalPadding
        }

        let centeredStart = (waterfallContentWidth - columnsWidth) / 2
        return max(WaterfallMetrics.contentHorizontalPadding, centeredStart)
    }

    private func layoutWaterfallColumn(_ column: WaterfallColumnLayers) {
        column.containerLayer.cornerRadius = 14
        column.containerLayer.masksToBounds = true
        column.containerLayer.backgroundColor = NSColor.controlBackgroundColor.withAlphaComponent(0.56).cgColor
        column.containerLayer.shadowOpacity = 0
        column.containerLayer.shadowRadius = 0
        column.containerLayer.shadowOffset = .zero
        column.headerLayer.isHidden = false
        column.appNameLayer.isHidden = false
        column.countLayer.isHidden = false

        let bounds = column.containerLayer.bounds
        let isSpaceFocused = spaceFocusWindowCount(for: column.column.appGroupIndex) > 0
        let isHovered = column.column.appGroupIndex == effectiveHoveredAppGroupIndex
@@ -3059,9 +4016,11 @@
            width: bounds.width,
            height: WaterfallMetrics.headerHeight
        )
        column.headerLayer.backgroundColor = (isSpaceFocused
            ? NSColor.systemFill.withAlphaComponent(0.10)
            : NSColor.controlBackgroundColor.withAlphaComponent(0.52)
        column.headerLayer.backgroundColor = (isHovered
            ? viewModeToggleBlueColor
            : (isSpaceFocused
                ? NSColor.systemFill.withAlphaComponent(0.10)
                : NSColor.controlBackgroundColor.withAlphaComponent(0.52))
        ).cgColor
        column.appNameLayer.frame = CGRect(
            x: WaterfallMetrics.columnHeaderTextInset,
@@ -3069,16 +4028,14 @@
            width: max(1, bounds.width - WaterfallMetrics.columnHeaderTextInset * 2),
            height: 16
        )
        column.appNameLayer.foregroundColor = (isHovered
            ? spaceLaneOccupiedColor
            : NSColor.labelColor
        ).cgColor
        column.appNameLayer.foregroundColor = (isHovered ? NSColor.white : NSColor.labelColor).cgColor
        column.countLayer.frame = CGRect(
            x: bounds.width - 48,
            y: bounds.height - 24,
            width: 36,
            height: 16
        )
        column.countLayer.foregroundColor = (isHovered ? NSColor.white : NSColor.secondaryLabelColor).cgColor

        let appGroupIndex = column.column.appGroupIndex
        let verticalOffset = clampedWaterfallColumnOffset(
@@ -3112,10 +4069,13 @@
        let bounds = card.containerLayer.bounds
        let isSelected = card.item.window.id == effectiveSelection?.windowID
        let isHovered = card.item.window.id == hoveredWindowID
        let isAppLinked = isHorizontalMasonryMode
            && card.item.appGroupIndex == appIconHoverLinkedAppGroupIndex
        applyWaterfallCardVisualState(
            card,
            selected: shouldShowSelectedVisual(isSelected: isSelected, isHovered: isHovered),
            hovered: isHovered
            hovered: isHovered,
            appLinked: isAppLinked
        )

        let outerInset: CGFloat = 0
@@ -3178,12 +4138,19 @@
        )
    }

    private func applyWaterfallCardVisualState(_ card: WaterfallCardLayers, selected: Bool, hovered: Bool) {
    private func applyWaterfallCardVisualState(
        _ card: WaterfallCardLayers,
        selected: Bool,
        hovered: Bool,
        appLinked: Bool
    ) {
        let isSpaceFocused = isWaterfallCardSpaceFocused(card)
        card.containerLayer.backgroundColor = (selected
            ? NSColor.windowBackgroundColor.withAlphaComponent(0.94)
            : 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)
@@ -3192,27 +4159,31 @@
            ? NSColor.controlAccentColor.withAlphaComponent(0.52)
            : hovered
                ? NSColor.controlAccentColor.withAlphaComponent(0.44)
                : appLinked
                    ? NSColor.controlAccentColor.withAlphaComponent(0.38)
                : isSpaceFocused
                    ? NSColor.controlAccentColor.withAlphaComponent(0.42)
                : NSColor.separatorColor.withAlphaComponent(0.28)
        ).cgColor
        card.containerLayer.borderWidth = (selected || hovered || isSpaceFocused) ? 1.5 : 1
        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 : isSpaceFocused ? 0.20 : 0
        card.containerLayer.shadowRadius = selected ? 22 : hovered ? 17 : isSpaceFocused ? 24 : 0
        card.containerLayer.shadowOpacity = selected ? 0.24 : hovered ? 0.14 : appLinked ? 0.16 : isSpaceFocused ? 0.20 : 0
        card.containerLayer.shadowRadius = selected ? 22 : hovered ? 17 : appLinked ? 18 : isSpaceFocused ? 24 : 0
        card.containerLayer.shadowOffset = selected
            ? CGSize(width: 0, height: -6)
            : hovered
                ? CGSize(width: 0, height: -2.5)
                : appLinked
                    ? CGSize(width: 0, height: -3)
                : isSpaceFocused
                    ? CGSize(width: 0, height: -5)
                    : .zero
        card.containerLayer.zPosition = selected ? 20 : hovered ? 10 : isSpaceFocused ? 8 : 0
        card.containerLayer.zPosition = selected ? 20 : hovered ? 12 : appLinked ? 10 : isSpaceFocused ? 8 : 0
        let focusedScale: CGFloat = selected ? 1.015 : isSpaceFocused ? 1.012 : 1.008
        card.containerLayer.transform = (selected || hovered || isSpaceFocused)
            ? CATransform3DMakeScale(focusedScale, focusedScale, 1)
            : CATransform3DIdentity
        card.containerLayer.shadowPath = (selected || hovered || isSpaceFocused)
        card.containerLayer.shadowPath = (selected || hovered || appLinked || isSpaceFocused)
            ? CGPath(
                roundedRect: card.containerLayer.bounds,
                cornerWidth: card.containerLayer.cornerRadius,
@@ -3220,7 +4191,9 @@
                transform: nil
            )
            : nil
        card.titleBarLayer.backgroundColor = NSColor.clear.cgColor
        card.titleBarLayer.backgroundColor = appLinked
            ? spaceLaneOccupiedColor.withAlphaComponent(0.18).cgColor
            : NSColor.clear.cgColor
        card.titleBarLayer.borderColor = NSColor.clear.cgColor
        card.titleBarLayer.borderWidth = 0
        card.shineLayer.opacity = selected ? 1 : 0
@@ -3765,15 +4738,67 @@
        )
    }

    private var isHorizontalMasonryMode: Bool {
        waterfallViewMode == .horizontalMasonry
    }

    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 viewModeToggleVisualState: ViewModeToggleVisualState {
        if isHorizontalMasonryMode {
            return isViewModeToggleButtonHovered ? .verticalAvailable : .horizontalSelected
        }
        return isViewModeToggleButtonHovered ? .horizontalAvailable : .verticalSelected
    }

    private func viewModeToggleVisualStateIsSelected(_ state: ViewModeToggleVisualState) -> Bool {
        switch state {
        case .horizontalSelected, .verticalSelected:
            return true
        case .horizontalAvailable, .verticalAvailable:
            return false
        }
    }

    private var viewModeToggleIconKind: String {
        viewModeToggleVisualState.rawValue
    }

    private var viewModeToggleAccessibilityLabel: String {
        switch nextWaterfallViewMode {
        case .verticalColumns:
            return "切换到纵栏瀑布"
        case .horizontalMasonry:
            return "切换到横栏瀑布"
        }
    }

    private var waterfallMaxScrollOffset: CGFloat {
        max(0, waterfallContentWidth - waterfallLayer.bounds.width)
        guard !isHorizontalMasonryMode else { return 0 }
        return max(0, waterfallContentWidth - waterfallLayer.bounds.width)
    }

    private func clampedWaterfallOffset(_ offset: CGFloat) -> CGFloat {
        min(max(0, offset), waterfallMaxScrollOffset)
    }

    private var horizontalMasonryMaxScrollOffset: CGFloat {
        max(0, horizontalMasonryContentHeight - waterfallLayer.bounds.height)
    }

    private func clampedHorizontalMasonryOffset(_ offset: CGFloat) -> CGFloat {
        min(max(0, offset), horizontalMasonryMaxScrollOffset)
    }

    private func waterfallMaxVerticalScrollOffset(for appGroupIndex: Int) -> CGFloat {
        guard !isHorizontalMasonryMode else { return 0 }

        guard
            let column = waterfallColumns.first(where: { $0.column.appGroupIndex == appGroupIndex })
        else {
@@ -3820,6 +4845,14 @@
        }

        return NSColor(calibratedRed: 0, green: 122 / 255, blue: 1, alpha: 1)
    }

    private var spaceLaneLockedFillColor: NSColor {
        if effectiveAppearance.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua {
            return NSColor(calibratedRed: 58 / 255, green: 148 / 255, blue: 1, alpha: 0.86)
        }

        return NSColor(calibratedRed: 90 / 255, green: 171 / 255, blue: 1, alpha: 0.82)
    }

    private func spaceLaneIdleOccupiedGradientColors() -> [NSColor] {
@@ -4042,13 +5075,38 @@
        return identifiers.joined(separator: " ")
    }

    private func layoutFullscreenMarkerLayer(_ layer: CALayer, in segmentBounds: CGRect) {
    private func splitViewAppNames(for space: QuickSwitchSpaceViewModel) -> [String] {
        guard space.type == .fullscreen else { return [] }

        let names = space.splitViewAppNames
            .prefix(2)
            .map { $0.trimmingCharacters(in: .whitespacesAndNewlines) }
            .filter { !$0.isEmpty }

        guard names.count >= 2 else { return [] }
        return names
    }

    private func layoutFullscreenMarkerLayer(
        _ layer: CALayer,
        in segmentBounds: CGRect,
        isSplitView: Bool = false
    ) {
        let markerFrame = fullscreenMarkerFrame(in: segmentBounds)
        layer.frame = markerFrame

        guard let shapeLayer = layer as? CAShapeLayer else { return }

        let bounds = shapeLayer.bounds
        if isSplitView {
            let path = CGMutablePath()
            path.move(to: CGPoint(x: bounds.midX, y: bounds.minY))
            path.addLine(to: CGPoint(x: bounds.midX, y: bounds.maxY))
            shapeLayer.path = path
            shapeLayer.lineCap = .butt
            return
        }

        let cornerLength = min(12, max(7, min(bounds.width, bounds.height) * 0.28))
        let path = CGMutablePath()

@@ -4069,6 +5127,7 @@
        path.addLine(to: CGPoint(x: 0, y: bounds.maxY - cornerLength))

        shapeLayer.path = path
        shapeLayer.lineCap = .round
    }

    private func fullscreenMarkerFrame(in segmentBounds: CGRect) -> CGRect {
@@ -4118,6 +5177,11 @@
                "frame": dictionary(from: item.containerLayer.frame),
                "visibleFrame": dictionary(from: visibleFrame),
                "iconFrame": dictionary(from: item.iconLayer.frame),
                "indexText": item.indexLayer.string ?? "",
                "indexFrame": dictionary(from: item.indexLayer.frame),
                "indexVisible": !item.indexLayer.isHidden && item.indexLayer.opacity > 0,
                "indexFontSize": Double(item.indexLayer.fontSize),
                "indexColor": colorDictionary(from: item.indexLayer.foregroundColor),
                "labelFrame": dictionary(from: item.labelLayer.frame),
                "labelTruncationMode": "middle",
                "badgeVisible": !item.badgeLayer.isHidden,
@@ -4191,12 +5255,14 @@
                "frame": dictionary(from: column.containerLayer.frame),
                "visibleFrame": dictionary(from: visibleFrame),
                "headerFrame": dictionary(from: column.headerLayer.frame),
                "headerBackgroundColor": colorDictionary(from: column.headerLayer.backgroundColor),
                "headerToFirstCardGap": headerToFirstCardGap.map(Double.init) ?? NSNull(),
                "topToFirstCardGap": topToFirstCardGap.map(Double.init) ?? NSNull(),
                "appNameFrame": dictionary(from: column.appNameLayer.frame),
                "appNameAlignment": column.appNameLayer.alignmentMode.rawValue,
                "appNameColor": colorDictionary(from: column.appNameLayer.foregroundColor),
                "countFrame": dictionary(from: column.countLayer.frame),
                "countColor": colorDictionary(from: column.countLayer.foregroundColor),
                "verticalScrollOffset": Double(waterfallColumnScrollOffsets[appGroupIndex] ?? 0),
                "maxVerticalScrollOffset": Double(waterfallMaxVerticalScrollOffset(for: appGroupIndex)),
                "cards": waterfallCardReports(for: column)
@@ -4283,6 +5349,7 @@
                "shadowRadius": Double(card.containerLayer.shadowRadius),
                "thumbnailFrame": dictionary(from: card.thumbnailLayer.frame),
                "titleBarFrame": dictionary(from: card.titleBarLayer.frame),
                "titleBarBackgroundColor": colorDictionary(from: card.titleBarLayer.backgroundColor),
                "titleBarBorderWidth": Double(card.titleBarLayer.borderWidth),
                "titleFrame": dictionary(from: card.titleLayer.frame),
                "metaFrame": dictionary(from: card.metaLayer.frame),
@@ -4390,6 +5457,8 @@
        var states: [String] = []
        let isSelected = card.item.window.id == effectiveSelection?.windowID
        let isHovered = card.item.window.id == hoveredWindowID
        let isAppLinked = isHorizontalMasonryMode
            && card.item.appGroupIndex == appIconHoverLinkedAppGroupIndex
        if shouldShowSelectedVisual(isSelected: isSelected, isHovered: isHovered) {
            states.append("selected")
        } else if isSelected {
@@ -4397,6 +5466,9 @@
        }
        if isHovered {
            states.append("hover")
        }
        if isAppLinked {
            states.append("appLinked")
        }
        if isWaterfallCardSpaceFocused(card) {
            states.append("spaceFocused")
@@ -4457,6 +5529,8 @@
                let fullscreenMarkerCenterRatio = fullscreenMarkerFrame.map {
                    Double($0.midY / max(1, segment.containerLayer.bounds.height))
                }
                let splitAppNames = splitViewAppNames(for: space)
                let splitAppLabelFrames = segment.splitAppLayers.map { dictionary(from: $0.frame) }
                return [
                    "displayUUID": display.displayUUID,
                    "displayLabel": display.displayLabel,
@@ -4465,12 +5539,32 @@
                    "type": spaceTypeName(space.type),
                    "visualStates": visualStates(for: space),
                    "fullscreenMarkerVisible": segment.fullscreenMarkerLayer != nil,
                    "fullscreenMarkerKind": segment.fullscreenMarkerLayer == nil ? "none" : "cornerBracket",
                    "fullscreenMarkerKind": fullscreenMarkerKind(
                        markerLayer: segment.fullscreenMarkerLayer,
                        splitAppNames: splitAppNames
                    ),
                    "fullscreenMarkerPathStyle": fullscreenMarkerPathStyle(
                        markerLayer: segment.fullscreenMarkerLayer,
                        splitAppNames: splitAppNames
                    ),
                    "fullscreenMarkerFrame": fullscreenMarkerFrame.map { dictionary(from: $0) } ?? NSNull(),
                    "fullscreenMarkerCenterRatio": fullscreenMarkerCenterRatio ?? NSNull(),
                    "splitViewAppNames": splitAppNames,
                    "splitViewLabelFrames": splitAppLabelFrames,
                    "splitViewLabelColors": segment.splitAppLayers.map {
                        colorDictionary(from: $0.foregroundColor)
                    },
                    "windowBlockCount": segment.windowBlocks.count,
                    "windowBlockColors": segment.windowBlocks.map { colorDictionary(from: $0.backgroundColor) },
                    "windowBlockFrames": segment.windowBlocks.map { dictionary(from: $0.frame) },
                    "labelColor": colorDictionary(from: segment.labelLayer.foregroundColor),
                    "countText": string(from: segment.countLayer.string),
                    "countVisible": !segment.countLayer.isHidden && segment.countLayer.opacity > 0,
                    "countColor": colorDictionary(from: segment.countLayer.foregroundColor),
                    "appColor": colorDictionary(from: segment.appLayer.foregroundColor),
                    "fullscreenMarkerStrokeColor": colorDictionary(
                        from: (segment.fullscreenMarkerLayer as? CAShapeLayer)?.strokeColor
                    ),
                    "backgroundKind": spaceLaneFillKind(for: segment.containerLayer),
                    "backgroundColor": colorDictionary(from: segment.containerLayer.backgroundColor),
                    "gradientColors": gradientColorDictionaries(from: segment.containerLayer),
@@ -4505,6 +5599,16 @@
        }
    }

    private func fullscreenMarkerKind(markerLayer: CALayer?, splitAppNames: [String]) -> String {
        guard markerLayer != nil else { return "none" }
        return splitAppNames.count >= 2 ? "splitViewPair" : "cornerBracket"
    }

    private func fullscreenMarkerPathStyle(markerLayer: CALayer?, splitAppNames: [String]) -> String {
        guard markerLayer != nil else { return "none" }
        return splitAppNames.count >= 2 ? "centerDividerOnly" : "cornerBracket"
    }

    private func visualStates(for space: QuickSwitchSpaceViewModel) -> [String] {
        var states: [String] = []
        if space.isCurrent {
@@ -4527,6 +5631,9 @@
        }
        if space.type == .fullscreen {
            states.append("fullscreen")
        }
        if splitViewAppNames(for: space).count >= 2 {
            states.append("splitView")
        }
        return states
    }
@@ -4553,6 +5660,16 @@
        ]
    }

    private func string(from textLayerValue: Any?) -> String {
        if let string = textLayerValue as? String {
            return string
        }
        if let attributedString = textLayerValue as? NSAttributedString {
            return attributedString.string
        }
        return ""
    }

    private func colorDictionary(from color: CGColor?) -> [String: Double] {
        guard let color,
              let nsColor = NSColor(cgColor: color)?.usingColorSpace(.deviceRGB)