WindowState.swift

import AppKit
import Combine
import Foundation
import SwiftUI

enum WindowKind: String, Codable {
    case standard
    case contextBuilder

    init(from decoder: Decoder) throws {
        let rawValue = try decoder.singleValueContainer().decode(String.self)
        switch rawValue {
        case Self.standard.rawValue:
            self = .standard
        case Self.contextBuilder.rawValue, "discoverAgent":
            self = .contextBuilder
        default:
            throw DecodingError.dataCorrupted(
                DecodingError.Context(
                    codingPath: decoder.codingPath,
                    debugDescription: "Unknown window kind: \(rawValue)"
                )
            )
        }
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        try container.encode(rawValue)
    }
}

enum WindowTitleFormatter {
    /// Default window title when no user workspace is active.
    /// Mirrors the app's display name so window and tab titles match the running distribution.
    static let defaultTitle: String = {
        let info = Bundle.main.infoDictionary
        let candidates = [info?["CFBundleDisplayName"] as? String, info?["CFBundleName"] as? String]
        let resolved = candidates
            .compactMap { $0?.trimmingCharacters(in: .whitespacesAndNewlines) }
            .first { !$0.isEmpty }
        return resolved ?? "RepoPrompt CE"
    }()

    static func compose(
        workspaceTitle: String,
        agentSessionTitle: String?,
        duplicateWorkspaceTitle: String? = nil
    ) -> String {
        let trimmedSessionTitle = agentSessionTitle?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
        guard !trimmedSessionTitle.isEmpty else { return workspaceTitle }

        let duplicateTitles = [workspaceTitle, duplicateWorkspaceTitle]
            .compactMap { $0?.trimmingCharacters(in: .whitespacesAndNewlines) }
        guard !duplicateTitles.contains(where: { trimmedSessionTitle.caseInsensitiveCompare($0) == .orderedSame }) else {
            return workspaceTitle
        }

        return "\(trimmedSessionTitle) — \(workspaceTitle)"
    }
}

enum PendingInteractionSurface {
    case contextualQuestion
    case agentQuestion
}

/// Represents a command from CLI or URL
struct AppCommand {
    let workspaceName: String?
    let fileList: [String]
    let promptText: String?
    let folderPath: String?

    /// NEW: prompt that should be saved to `PromptViewModel`
    let newPrompt: (title: String, content: String)?

    /// When true, attempt to focus an existing window for the given workspace/folder if already open.
    let focus: Bool?

    /// When true, do not persist this workspace to disk/index (only keep in memory).
    /// If set, you can treat this as "ephemeral" usage.
    let ephemeral: Bool?

    /// When false, skip saving changes to disk/index. If nil or true, persist by default.
    let persist: Bool?

    var isEmpty: Bool {
        workspaceName == nil
            && fileList.isEmpty
            && promptText == nil
            && folderPath == nil
            && newPrompt == nil // <- include new field
            && focus == nil
            && ephemeral == nil
            && persist == nil
    }
}

/// Holds all of the per-window managers/services.
/// Each new window in the app gets a fresh instance of WindowState.
@MainActor
class WindowState: ObservableObject {
    // MARK: - Shared Services

    /// Single shared MCP service instance across all windows
    private static let sharedMCPService = MCPService()

    // MARK: - Window identification

    private(set) static var windowCounter = 0
    let windowID: Int

    @Published var kind: WindowKind = .standard

    // MARK: - Focus Tracking

    @Published var isCurrentlyFocused: Bool = false

    /// Per-window teardown guard. Not @Published (we don't want SwiftUI updates during teardown).
    private(set) var isClosing: Bool = false

    private var focusCancellables = Set<AnyCancellable>()
    private weak var focusObservedWindow: NSWindow?

    /// Holds Combine subscriptions local to this window state
    private var cancellables = Set<AnyCancellable>()

    /// Called whenever `isCurrentlyFocused` changes.
    var onFocusChanged: ((Bool) -> Void)?

    // MARK: - Per-Window View Models

    let workspaceFileContextStore: WorkspaceFileContextStore
    let workspaceSearchService: WorkspaceSearchService
    let selectionCoordinator: WorkspaceSelectionCoordinator
    let workspaceFilesViewModel: WorkspaceFilesViewModel
    let settingsManager: WindowSettingsManager
    let promptManager: PromptViewModel
    let oracleViewModel: OracleViewModel
    let apiSettingsViewModel: APISettingsViewModel
    let contextBuilderAgentViewModel: ContextBuilderAgentViewModel
    let agentModeViewModel: AgentModeViewModel
    #if DEBUG
        let agentChatStressHarness: AgentChatStressHarness?
    #endif

    // MARK: - MCP Server (one per window)

    let mcpServer: MCPServerViewModel
    let closeCoordinator: WindowCloseCoordinator

    // MARK: - Services and Utilities

    let keyManager: KeyManager
    let aiQueriesService: AIQueriesService
    let chatDataService: ChatDataService

    // MARK: - Possibly shared references

    let workspaceManager: WorkspaceManagerViewModel
    weak var windowStatesManager: WindowStatesManager?

    /// Reference to the NSWindow this state is associated with
    weak var nsWindow: NSWindow?
    private var windowDelegateProxy: InterceptingWindowDelegateProxy?

    // MARK: - Agent Mode Titlebar Accessory

    /// Titlebar accessory controller for Agent mode ("New Session" button near traffic lights)
    private weak var agentTitlebarAccessory: AgentModeTitlebarAccessoryViewController?
    /// Whether Agent mode has requested the titlebar accessory be visible
    private var wantsAgentTitlebarAccessory: Bool = false
    /// Action to call when the "New Session" button is tapped
    private var agentNewSessionAction: (() -> Void)?

    /// The sticky instance number assigned for this window's current workspace (monotonically increasing per workspace).
    /// Nil when no workspace is active yet.
    @Published var workspaceInstanceNumber: Int? = nil

    /// Convenience: the workspace name with an instance suffix " (N)" when N ≥ 2,
    /// except for the default/system workspace which always shows the app name.
    var workspaceDisplayName: String {
        guard let ws = workspaceManager.activeWorkspace else {
            return WindowTitleFormatter.defaultTitle
        }

        if ws.isSystemWorkspace {
            return WindowTitleFormatter.defaultTitle
        }

        let base = ws.name
        if let n = workspaceInstanceNumber, n >= 2 {
            return "\(base) (\(n))"
        }
        return base
    }

    /// Source of truth for the SwiftUI scene title (window title and native tab name).
    /// Published so the scene keeps re-applying it; otherwise SwiftUI falls back to the
    /// app display name whenever it refreshes the window chrome.
    @Published private(set) var displayedWindowTitle: String = WindowTitleFormatter.defaultTitle

    // Cache to survive transient activeWorkspace == nil. This may include Agent session context.
    private var lastKnownResolvedTitle: String = WindowTitleFormatter.defaultTitle
    private var lastAppliedWindowTitle: String?

    private func resolvedWindowTitle() -> String {
        guard let ws = workspaceManager.activeWorkspace else {
            // If we expect a workspace but it is temporarily unresolved, do not stomp to default.
            if workspaceManager.activeWorkspaceID != nil {
                return lastKnownResolvedTitle
            }

            return WindowTitleFormatter.defaultTitle
        }

        let workspaceTitle = resolvedWorkspaceWindowTitle(for: ws)
        let resolvedTitle = WindowTitleFormatter.compose(
            workspaceTitle: workspaceTitle,
            agentSessionTitle: resolvedAgentSessionTitleForWindowTitle(activeWorkspace: ws),
            duplicateWorkspaceTitle: ws.isSystemWorkspace ? WindowTitleFormatter.defaultTitle : ws.name
        )
        lastKnownResolvedTitle = resolvedTitle
        return resolvedTitle
    }

    private func resolvedWorkspaceWindowTitle(for workspace: WorkspaceModel) -> String {
        if workspace.isSystemWorkspace {
            return WindowTitleFormatter.defaultTitle
        }

        let base = workspace.name
        if let n = workspaceInstanceNumber, n >= 2 {
            return "\(base) (\(n))"
        }
        return base
    }

    private func resolvedAgentSessionTitleForWindowTitle(activeWorkspace: WorkspaceModel) -> String? {
        guard !activeWorkspace.isSystemWorkspace,
              promptManager.activeComposeTabID != nil
        else {
            return nil
        }

        let rawTitle = promptManager.activeComposeTabID.flatMap { workspaceManager.composeTabName(with: $0) }
        return AgentSessionRestoreSupport.normalizedSessionTitle(rawTitle)
    }

    enum WindowTitleUpdateReason {
        case windowAttached
        case workspaceChanged
        case focusChanged
        case appBecameActive
        case activeComposeTabChanged
        case agentSessionNameChanged
        case explicit
        case unspecified
    }

    /// Command queue to store all pending commands
    private var commandQueue: [AppCommand] = []

    /// Lazily scheduled task to coalesce window title updates outside of mutation scopes.
    private var pendingWindowTitleUpdateTask: Task<Void, Never>?
    /// Lazily scheduled task to coalesce focus updates outside of mutation scopes.
    private var pendingFocusUpdateTask: Task<Void, Never>?
    /// Lazily scheduled task to coalesce focus side-effects outside of mutation scopes.
    private var pendingFocusSideEffectsTask: Task<Void, Never>?

    private var shouldSuppressObservationSideEffects: Bool {
        // Avoid SwiftUI observation churn during teardown/termination.
        isClosing || WindowStatesManager.shared.isTerminating
    }

    func beginClose() {
        guard !isClosing else { return }
        isClosing = true

        let manager = windowStatesManager ?? WindowStatesManager.shared
        if !manager.isTerminating {
            manager.markWindowAsExplicitlyClosing(windowID: windowID)
        }
        closeCoordinator.beginClose()
        onFocusChanged = nil
        removeFocusObservers()
        pendingWindowTitleUpdateTask?.cancel()
        pendingWindowTitleUpdateTask = nil
        pendingFocusUpdateTask?.cancel()
        pendingFocusUpdateTask = nil
        pendingFocusSideEffectsTask?.cancel()
        pendingFocusSideEffectsTask = nil
        detachTitlebarAccessoryControllers(from: nsWindow)
        clearTitlebarAccessoryRequestsForClose()
        apiSettingsViewModel.prepareForWindowClose()
        contextBuilderAgentViewModel.prepareForWindowClose()
        workspaceManager.prepareForWindowClose()
        promptManager.gitViewModel.prepareForWindowClose()
    }

    private var pendingRestoreEntry: WindowSessionEntry?
    private(set) var claimedInitialRefreshDeferralID: UUID?
    private(set) var claimedInitialRefreshDeferralWaiterID: UUID?

    // MARK: - Initialization

    convenience init() {
        self.init(
            contextBuilderProviderFactory: nil,
            loadStoredAPISettingsDataOnInit: true,
            codexModelPollingService: .shared
        )
    }

    #if DEBUG
        convenience init(contextBuilderProviderFactory: @escaping ContextBuilderAgentViewModel.ProviderFactory) {
            self.init(
                contextBuilderProviderFactory: Optional(contextBuilderProviderFactory),
                loadStoredAPISettingsDataOnInit: true,
                codexModelPollingService: .shared
            )
        }

        convenience init(
            codexModelPollingService: CodexModelPollingService,
            loadStoredAPISettingsDataOnInit: Bool
        ) {
            self.init(
                contextBuilderProviderFactory: nil,
                loadStoredAPISettingsDataOnInit: loadStoredAPISettingsDataOnInit,
                codexModelPollingService: codexModelPollingService
            )
        }

    #endif

    private init(
        contextBuilderProviderFactory: ContextBuilderAgentViewModel.ProviderFactory?,
        loadStoredAPISettingsDataOnInit: Bool,
        codexModelPollingService: CodexModelPollingService
    ) {
        // Assign a unique window ID
        WindowState.windowCounter += 1
        windowID = WindowState.windowCounter
        let manager = WindowStatesManager.shared

        let claimedInitialRefreshDeferral = manager.claimInitialRefreshDeferralForNewWindow()
        let deferredInitialAgentSystemWorkspaceRefresh = claimedInitialRefreshDeferral != nil
        claimedInitialRefreshDeferralID = claimedInitialRefreshDeferral?.id
        claimedInitialRefreshDeferralWaiterID = claimedInitialRefreshDeferral?.waiterID

        // ️⃣ Connect to the global WindowStatesManager singleton
        windowStatesManager = manager

        let composition = WindowStateCompositionFactory.make(
            windowID: windowID,
            deferredInitialAgentSystemWorkspaceRefresh: deferredInitialAgentSystemWorkspaceRefresh,
            sharedMCPService: Self.sharedMCPService,
            contextBuilderProviderFactory: contextBuilderProviderFactory,
            loadStoredAPISettingsDataOnInit: loadStoredAPISettingsDataOnInit,
            codexModelPollingService: codexModelPollingService
        )

        workspaceFileContextStore = composition.workspaceFileContextStore
        workspaceSearchService = composition.workspaceSearchService
        selectionCoordinator = composition.selectionCoordinator
        workspaceFilesViewModel = composition.workspaceFilesViewModel
        settingsManager = composition.settingsManager
        promptManager = composition.promptManager
        oracleViewModel = composition.oracleViewModel
        apiSettingsViewModel = composition.apiSettingsViewModel
        contextBuilderAgentViewModel = composition.contextBuilderAgentViewModel
        agentModeViewModel = composition.agentModeViewModel
        #if DEBUG
            agentChatStressHarness = composition.agentChatStressHarness
        #endif
        mcpServer = composition.mcpServer
        closeCoordinator = composition.closeCoordinator
        keyManager = composition.keyManager
        aiQueriesService = composition.aiQueriesService
        chatDataService = composition.chatDataService
        workspaceManager = composition.workspaceManager

        // Set up additional actions
        setupSendPromptAction()
        #if DEBUG
            if AppLaunchConfiguration.current.forcesMCPAutoStart {
                setupMCPAutoStart()
            }
        #endif

        // Set up workspace switch listener to sync settings and validate prompts
        workspaceManager.addWorkspaceDidSwitchListener(label: "windowState") { [weak self] workspace in
            guard let self else { return }
            promptManager.syncSettingsFromSettingsManager()

            // Validate workspace skills for workspace root folders (if previously installed)
            let roots = workspace.map(WorkspaceManagerViewModel.loadableRepoPaths(for:)) ?? []
            Task.detached(priority: .utility) {
                await MCPPromptValidationService.shared.validateWorkspaceSkills(forRoots: roots)
            }
        }

        // Process any queued commands once the workspace is initialized
        workspaceManager.onceInitialized { [weak self] in
            guard let self else { return }
            Task {
                self.applyPendingRestoreEntryIfPossible()
                await self.processCommands()
            }
        }

        // Keep the window title in sync when this window's active compose tab changes,
        // so the Agent session portion of the title does not go stale.
        NotificationCenter.default.publisher(for: .activeComposeTabChanged)
            .receive(on: RunLoop.main)
            .sink { [weak self] notification in
                guard let self,
                      let notifiedWindowID = notification.userInfo?["windowID"] as? Int,
                      notifiedWindowID == windowID
                else { return }
                requestWindowTitleUpdate(reason: .activeComposeTabChanged)
            }
            .store(in: &cancellables)

        NotificationCenter.default.publisher(for: .composeTabNameChanged)
            .receive(on: RunLoop.main)
            .sink { [weak self] notification in
                guard let self,
                      let notifiedWindowID = notification.userInfo?["windowID"] as? Int,
                      notifiedWindowID == windowID,
                      let tabID = notification.userInfo?["tabID"] as? UUID,
                      tabID == promptManager.activeComposeTabID
                else { return }
                requestWindowTitleUpdate(reason: .agentSessionNameChanged)
            }
            .store(in: &cancellables)
    }

    private func setupMCPAutoStart() {
        Task { [weak self] in
            await self?.mcpServer.startServer()
        }
    }

    private func setupSendPromptAction() {
        oracleViewModel.setupSendPromptAction()
    }

    // MARK: - Window Management

    /// Attaches the NSWindow to this state and updates the title.
    /// Uses deferred title update to avoid triggering layout during window lifecycle events
    /// (REPOPROMPT-1K4 fix).
    func attachWindow(_ window: NSWindow?) {
        // Detach path (always do the cleanup even if both are nil)
        if window == nil {
            let oldWindow = nsWindow
            detachTitlebarAccessoryControllers(from: oldWindow)
            nsWindow = nil
            removeFocusObservers()
            pendingWindowTitleUpdateTask?.cancel()
            pendingWindowTitleUpdateTask = nil
            pendingFocusUpdateTask?.cancel()
            pendingFocusUpdateTask = nil
            scheduleFocusUpdate(false)
            return
        }
        guard let window else { return }

        if nsWindow === window {
            configureWindowChrome(for: window)
            ensureWindowDelegateProxy(for: window)
            scheduleFocusUpdate(from: window)
            requestWindowTitleUpdate(reason: .windowAttached)
            applyAgentTitlebarAccessoryIfPossible()
            return
        }

        if let oldWindow = nsWindow, oldWindow !== window {
            detachTitlebarAccessoryControllers(from: oldWindow)
        }
        nsWindow = window
        if AppLaunchConfiguration.current.isUITestSession {
            DispatchQueue.main.async {
                NSApp.activate(ignoringOtherApps: true)
                window.makeKeyAndOrderFront(nil)
            }
        }
        configureWindowChrome(for: window)
        installFocusObservers(for: window)
        scheduleFocusUpdate(from: window)
        ensureWindowDelegateProxy(for: window)
        // Use deferred update to avoid recursive layout issues
        requestWindowTitleUpdate(reason: .windowAttached)
        // Install Agent mode titlebar accessory if requested before window was attached
        applyAgentTitlebarAccessoryIfPossible()
    }

    private func configureWindowChrome(for window: NSWindow) {
        // Keep titlebar visually continuous with content (no horizontal separator).
        window.toolbar?.showsBaselineSeparator = false
        // SwiftUI can recreate toolbar chrome during toolbar updates; re-apply on next runloop.
        DispatchQueue.main.async { [weak window] in
            window?.toolbar?.showsBaselineSeparator = false
        }
    }

    private func ensureWindowDelegateProxy(for window: NSWindow) {
        if let proxy = windowDelegateProxy {
            if window.delegate !== proxy {
                proxy.forwardedDelegate = window.delegate
                window.delegate = proxy
            }
        } else {
            let proxy = InterceptingWindowDelegateProxy(windowState: self, forwardedDelegate: window.delegate)
            windowDelegateProxy = proxy
            window.delegate = proxy
        }
    }

    private func installFocusObservers(for window: NSWindow) {
        guard focusObservedWindow !== window else { return }
        removeFocusObservers()
        focusObservedWindow = window

        let nc = NotificationCenter.default

        nc.publisher(for: NSWindow.didBecomeKeyNotification, object: window)
            .receive(on: RunLoop.main)
            .sink { [weak self] _ in
                guard let self else { return }
                let appIsActive = NSApplication.shared.isActive
                scheduleFocusUpdate(appIsActive)
            }
            .store(in: &focusCancellables)

        nc.publisher(for: NSWindow.didResignKeyNotification, object: window)
            .receive(on: RunLoop.main)
            .sink { [weak self] _ in
                self?.scheduleFocusUpdate(false)
            }
            .store(in: &focusCancellables)

        nc.publisher(for: NSApplication.didBecomeActiveNotification)
            .receive(on: RunLoop.main)
            .sink { [weak self, weak window] _ in
                guard let self, let window else { return }
                scheduleFocusUpdate(window.isKeyWindow)
            }
            .store(in: &focusCancellables)

        nc.publisher(for: NSApplication.didResignActiveNotification)
            .receive(on: RunLoop.main)
            .sink { [weak self] _ in
                self?.scheduleFocusUpdate(false)
            }
            .store(in: &focusCancellables)
    }

    private func removeFocusObservers() {
        focusCancellables.removeAll()
        focusObservedWindow = nil
    }

    private func setFocused(_ focused: Bool) {
        guard !shouldSuppressObservationSideEffects else { return }
        guard isCurrentlyFocused != focused else { return }
        isCurrentlyFocused = focused
        workspaceFilesViewModel.setWindowFocused(focused)
        scheduleFocusSideEffects(focused)
    }

    private func scheduleFocusUpdate(from window: NSWindow) {
        let focused = NSApplication.shared.isActive && window.isKeyWindow
        scheduleFocusUpdate(focused)
    }

    private func scheduleFocusUpdate(_ focused: Bool) {
        guard !shouldSuppressObservationSideEffects else { return }
        pendingFocusUpdateTask?.cancel()
        pendingFocusUpdateTask = Task { [weak self] in
            guard let self else { return }
            await Task.yield()
            guard !shouldSuppressObservationSideEffects else { return }
            applyFocus(focused)
        }
    }

    private func scheduleFocusSideEffects(_ focused: Bool) {
        guard !shouldSuppressObservationSideEffects else { return }
        pendingFocusSideEffectsTask?.cancel()
        pendingFocusSideEffectsTask = Task { [weak self] in
            guard let self else { return }
            await Task.yield()
            guard !shouldSuppressObservationSideEffects else { return }
            guard isCurrentlyFocused == focused else { return }
            onFocusChanged?(focused)
        }
    }

    @MainActor
    private func applyFocus(_ focused: Bool) {
        setFocused(focused)
    }

    /// Safe to call from WindowAccessor notifications; doesn't mutate SwiftUI state.
    private func reassertWindowTitle() {
        guard !shouldSuppressObservationSideEffects else { return }
        applyWindowTitleIfNeeded(resolvedWindowTitle())
    }

    @MainActor
    private func applyWindowTitleIfNeeded(_ title: String) {
        if displayedWindowTitle != title {
            displayedWindowTitle = title
        }
        guard let window = nsWindow else { return }
        if window.title == title, lastAppliedWindowTitle == title {
            return
        }
        window.title = title
        lastAppliedWindowTitle = title
    }

    func makeCloseImpactSnapshot() -> WindowCloseImpactSnapshot {
        let manager = windowStatesManager ?? WindowStatesManager.shared
        let allWindows = manager.allWindows
        let mcpEnabledWindowIDs = Set(manager.mcpEnabledWindowIDs())
        let activityItems = workspaceManager.activeSessionSnapshot().items.map {
            WindowCloseActivityItem(
                id: $0.id,
                count: $0.count,
                singularLabel: $0.singularLabel,
                pluralLabel: $0.pluralLabel
            )
        }

        return WindowCloseImpactSnapshot(
            isTerminating: manager.isTerminating,
            isLastAppWindow: allWindows.count == 1 && allWindows.first === self,
            isLastMCPEnabledWindow: mcpEnabledWindowIDs.count == 1 && mcpEnabledWindowIDs.contains(windowID),
            activeItems: activityItems,
            mcp: mcpServer.closeSafetyState
        )
    }

    func closeActiveComposeTabFromShortcut() {
        guard let activeTabID = promptManager.activeComposeTabID,
              promptManager.canCloseActiveComposeTab
        else {
            return
        }

        Task { await promptManager.stashTab(activeTabID) }
    }

    /// Starts a new Agent session tab (mirrors the titlebar "New Session" control).
    func startNewAgentSessionFromGlobalShortcut() {
        guard workspaceManager.activeWorkspace?.isSystemWorkspace == false else { return }

        Task {
            let activeTabID = await MainActor.run { agentModeViewModel.currentTabID }
            if await MainActor.run(body: { agentModeViewModel.shouldSwallowNewSessionClick(for: activeTabID) }) {
                return
            }
            await agentModeViewModel.createAndActivateSessionTab()
        }
    }

    func requestClose(authorization: WindowCloseAuthorization? = nil) {
        if let authorization {
            closeCoordinator.enqueueAuthorization(authorization)
        }
        nsWindow?.performClose(nil)
    }

    // MARK: - Agent Mode Titlebar Accessory

    @discardableResult
    private func removeTitlebarAccessory(
        _ accessory: NSTitlebarAccessoryViewController?,
        from window: NSWindow? = nil
    ) -> Bool {
        guard let accessory, let window = window ?? nsWindow else { return false }
        let indexes = window.titlebarAccessoryViewControllers.enumerated().compactMap { index, candidate in
            candidate === accessory ? index : nil
        }
        guard !indexes.isEmpty else { return false }

        for index in indexes.sorted(by: >) {
            window.removeTitlebarAccessoryViewController(at: index)
        }
        configureWindowChrome(for: window)
        return true
    }

    private func detachTitlebarAccessoryControllers(from window: NSWindow?) {
        let accessories: [NSTitlebarAccessoryViewController] = [
            agentTitlebarAccessory as NSTitlebarAccessoryViewController?
        ].compactMap(\.self)

        if let window, !accessories.isEmpty {
            let accessoryIDs = Set(accessories.map { ObjectIdentifier($0) })
            let indexes = window.titlebarAccessoryViewControllers.enumerated().compactMap { index, candidate in
                accessoryIDs.contains(ObjectIdentifier(candidate)) ? index : nil
            }

            for index in indexes.sorted(by: >) {
                window.removeTitlebarAccessoryViewController(at: index)
            }
            if !indexes.isEmpty {
                configureWindowChrome(for: window)
            }
        }

        agentTitlebarAccessory = nil
    }

    private func clearTitlebarAccessoryRequestsForClose() {
        wantsAgentTitlebarAccessory = false
        agentNewSessionAction = nil
    }

    /// Shows or hides the Agent mode titlebar accessory ("New Session" button near traffic lights).
    /// - Parameters:
    ///   - visible: Whether to show the accessory
    ///   - onNewSession: Action to call when button is tapped (required when visible is true)
    func setAgentTitlebarAccessoryVisible(_ visible: Bool, onNewSession: (() -> Void)? = nil) {
        if visible {
            guard !shouldSuppressObservationSideEffects else { return }
            wantsAgentTitlebarAccessory = true
            agentNewSessionAction = onNewSession
            applyAgentTitlebarAccessoryIfPossible()
        } else {
            wantsAgentTitlebarAccessory = false
            agentNewSessionAction = nil
            removeAgentTitlebarAccessory()
        }
    }

    /// Installs the titlebar accessory if conditions are met (Agent mode active + window attached)
    private func applyAgentTitlebarAccessoryIfPossible() {
        guard !shouldSuppressObservationSideEffects,
              wantsAgentTitlebarAccessory,
              let window = nsWindow,
              let action = agentNewSessionAction
        else {
            return
        }

        if let existing = agentTitlebarAccessory {
            existing.update(onNewSession: action)
            if !window.titlebarAccessoryViewControllers.contains(where: { $0 === existing }) {
                window.addTitlebarAccessoryViewController(existing)
            }
        } else {
            let accessory = AgentModeTitlebarAccessoryViewController(onNewSession: action)
            window.addTitlebarAccessoryViewController(accessory)
            agentTitlebarAccessory = accessory
        }
        configureWindowChrome(for: window)
    }

    /// Removes the titlebar accessory from the window
    private func removeAgentTitlebarAccessory() {
        let accessory = agentTitlebarAccessory
        removeTitlebarAccessory(accessory)
        agentTitlebarAccessory = nil
    }

    func requestWindowTitleUpdate(reason: WindowTitleUpdateReason = .unspecified) {
        _ = reason
        scheduleWindowTitleUpdate()
    }

    /// Updates the window title to include the workspace name and instance number
    func updateWindowTitleIfPossible() {
        requestWindowTitleUpdate(reason: .explicit)
    }

    /// Only update the window title after a deferred hop to avoid recursive layout issues.
    private func scheduleWindowTitleUpdate() {
        guard !shouldSuppressObservationSideEffects else { return }
        pendingWindowTitleUpdateTask?.cancel()
        pendingWindowTitleUpdateTask = Task { [weak self] in
            guard let self else { return }
            // Ensure this cannot run re-entrantly during a layout/constraints pass.
            await Task.yield()
            guard !shouldSuppressObservationSideEffects else { return }
            performWindowTitleUpdateIfWorkspaceAvailable()
        }
    }

    @MainActor
    private func performWindowTitleUpdateIfWorkspaceAvailable() {
        applyWindowTitleIfNeeded(resolvedWindowTitle())
    }

    // ------------------------------------------------------------------
    // MARK: – MCP server helpers (simple wrappers)

    /// ------------------------------------------------------------------
    func startMCPServer() {
        Task { try? await WindowState.sharedMCPService.join(windowID: windowID) }
    }

    func stopMCPServer() {
        Task { await WindowState.sharedMCPService.leave(windowID: windowID) }
    }

    // MARK: - Command handling

    /// Decodes percent-encodings and expands '~' in a file path
    private func decodeAndExpandTilde(_ rawPath: String) -> String {
        // Decode percent-encoded strings, e.g. "%7E" -> "~", "%20" -> " "
        guard let decoded = rawPath.removingPercentEncoding else {
            return (rawPath as NSString).expandingTildeInPath
        }
        // Then expand '~'
        return (decoded as NSString).expandingTildeInPath
    }

    func enqueueCommand(_ command: AppCommand) {
        commandQueue.append(command)
        // If the workspace manager is already initialized, process now
        if workspaceManager.isInitialized {
            Task { await processCommands() }
        }
    }

    func applyWindowRestoreEntry(_ entry: WindowSessionEntry) {
        guard !entry.isEphemeral else { return }
        pendingRestoreEntry = entry
        applyPendingRestoreEntryIfPossible()
    }

    private func applyPendingRestoreEntryIfPossible() {
        guard workspaceManager.isInitialized else { return }
        guard let entry = pendingRestoreEntry else { return }
        pendingRestoreEntry = nil

        Task {
            await restoreWorkspace(from: entry)
        }
    }

    private func restoreWorkspace(from entry: WindowSessionEntry) async {
        #if DEBUG
            let restoreStartMS = WorkspaceRestorePerfLog.timestampMSIfEnabled()
        #endif
        if let target = resolveWorkspace(for: entry) {
            #if DEBUG
                WorkspaceRestorePerfLog.log(
                    "restore.window workspaceResolved windowID=\(windowID) workspaceID=\(WorkspaceRestorePerfLog.shortID(target.id)) workspaceName=\(target.name) entryWorkspaceID=\(WorkspaceRestorePerfLog.shortID(entry.workspaceID))"
                )
            #endif
            _ = await workspaceManager.requestWorkspaceSwitch(to: target, saveState: true, reason: "restore")
            #if DEBUG
                if let restoreStartMS {
                    WorkspaceRestorePerfLog.log(
                        "restore.window workspaceApplied windowID=\(windowID) workspaceID=\(WorkspaceRestorePerfLog.shortID(target.id)) duration=\(WorkspaceRestorePerfLog.formatElapsedMS(since: restoreStartMS))"
                    )
                }
            #endif
            return
        }

        #if DEBUG
            if let restoreStartMS {
                WorkspaceRestorePerfLog.log(
                    "restore.window workspaceMissing windowID=\(windowID) entryWorkspaceID=\(WorkspaceRestorePerfLog.shortID(entry.workspaceID)) entryName=\(entry.workspaceName ?? "nil") duration=\(WorkspaceRestorePerfLog.formatElapsedMS(since: restoreStartMS))"
                )
            }
        #endif
        // No existing workspace matches; leave the window in its default state.
    }

    private func resolveWorkspace(for entry: WindowSessionEntry) -> WorkspaceModel? {
        let workspaces = workspaceManager.workspaces

        if let id = entry.workspaceID, let match = workspaces.first(where: { $0.id == id }) {
            return match
        }

        if let path = entry.primaryRepoPath {
            let expanded = (path as NSString).expandingTildeInPath
            if let match = workspaces.first(where: { workspace in
                workspace.repoPaths.contains { repoPath in
                    (repoPath as NSString).expandingTildeInPath == expanded
                }
            }) {
                return match
            }
        }

        if let name = entry.workspaceName, !name.isEmpty,
           let match = workspaces.first(where: { $0.name == name })
        {
            return match
        }

        if entry.isSystemWorkspace,
           let match = workspaces.first(where: { $0.isSystemWorkspace })
        {
            return match
        }

        return nil
    }

    // No workspace creation fallback; restoration is best-effort for existing workspaces only.

    func processCommands() async {
        while !commandQueue.isEmpty {
            let command = commandQueue.removeFirst()
            await handleCommand(command)
        }
    }

    @MainActor
    func routeToAgentSession(_ route: AgentSessionDeepLinkRoute) async -> AgentSessionRouteResult {
        await waitForWorkspaceInitializationForRouting()

        guard let targetWorkspace = workspaceManager.workspace(withID: route.workspaceID) else {
            return .workspaceUnavailable
        }

        NSApplication.shared.activate(ignoringOtherApps: true)
        if let window = nsWindow {
            window.makeKeyAndOrderFront(nil)
        } else {
            focusWindowIfPossible()
        }

        if workspaceManager.activeWorkspaceID != route.workspaceID {
            let switchResult = await workspaceManager.requestWorkspaceSwitch(to: targetWorkspace, saveState: true)
            if !switchResult.didSwitch {
                return .workspaceSwitchBlocked(switchResult.message)
            }
        }

        guard let activeWorkspace = workspaceManager.activeWorkspace,
              activeWorkspace.id == route.workspaceID
        else {
            return .workspaceUnavailable
        }

        let tabIsActive = activeWorkspace.composeTabs.contains(where: { $0.id == route.tabID })
        let tabIsStashed = activeWorkspace.stashedTabs.contains(where: { $0.tab.id == route.tabID })
        guard tabIsActive || tabIsStashed else {
            return .tabUnavailable
        }

        if let sessionID = route.sessionID {
            let activationResult = await agentModeViewModel.activateRoutedAgentSession(
                tabID: route.tabID,
                sessionID: sessionID,
                workspace: activeWorkspace
            )
            guard activationResult == .ready else {
                return agentSessionRouteResult(for: activationResult)
            }
        }

        if tabIsStashed {
            guard await promptManager.restoreStashedComposeTab(containingTabID: route.tabID) != nil else {
                return .tabUnavailable
            }
        } else if promptManager.activeComposeTabID != route.tabID {
            await promptManager.switchComposeTab(route.tabID)
        }

        guard promptManager.activeComposeTabID == route.tabID else {
            return .tabUnavailable
        }
        guard let finalWorkspace = workspaceManager.activeWorkspace,
              finalWorkspace.id == route.workspaceID
        else {
            return .workspaceUnavailable
        }
        let finalActivationResult = await agentModeViewModel.activateRoutedAgentSession(
            tabID: route.tabID,
            sessionID: route.sessionID,
            workspace: finalWorkspace
        )
        guard finalActivationResult == .ready else {
            return agentSessionRouteResult(for: finalActivationResult)
        }

        if let window = nsWindow {
            window.makeKeyAndOrderFront(nil)
        } else {
            focusWindowIfPossible()
        }
        return .routed
    }

    @MainActor
    private func waitForWorkspaceInitializationForRouting() async {
        guard !workspaceManager.isInitialized else {
            return
        }
        await workspaceManager.awaitInitialized()
    }

    private func agentSessionRouteResult(for activationResult: AgentRouteSessionActivationResult) -> AgentSessionRouteResult {
        switch activationResult {
        case .ready:
            .routed
        case .sessionNotFound:
            .sessionUnavailable
        case .sessionWorkspaceMismatch, .sessionTabMismatch:
            .sessionMismatch
        case .blockedByActiveDifferentSession:
            .blockedByActiveDifferentSession
        }
    }

    // MARK: - Handling URL commands

    func handleIncomingURL(_ url: URL) {
        guard let comps = URLComponents(url: url, resolvingAgainstBaseURL: false),
              AppDeepLinkURLScheme.isSupported(comps.scheme)
        else {
            return
        }

        // Check for prompt:// URLs first
        if comps.host?.lowercased() == "prompt" {
            let title = comps.queryItems?.first(where: { $0.name == "title" })?.value?
                .removingPercentEncoding?.trimmingCharacters(in: .whitespacesAndNewlines) ?? "Untitled Prompt"
            let content = comps.queryItems?.first(where: { $0.name == "content" })?.value?
                .removingPercentEncoding ?? ""

            /// Optional "focus" flag still works
            func flag(_ name: String) -> Bool? {
                guard let v = comps.queryItems?.first(where: { $0.name == name })?.value else { return nil }
                switch v.lowercased() { case "1", "true": return true
                case "0", "false": return false
                default: return nil }
            }
            let focusFlag = flag("focus")

            let cmd = AppCommand(
                workspaceName: nil,
                fileList: [],
                promptText: nil,
                folderPath: nil,
                newPrompt: (title, content),
                focus: focusFlag,
                ephemeral: nil,
                persist: nil
            )

            // Send to a window exactly the same way we already do for /open
            if focusFlag == true,
               let wsMgr = windowStatesManager,
               let front = wsMgr.latestWindowState
            { // fall back to latest-created
                front.enqueueCommand(cmd)
            } else {
                enqueueCommand(cmd)
            }
            return // ← we handled the prompt command
        }

        // Require host == "open" to match repoprompt-ce://open/~/MyProject
        guard let host = comps.host?.lowercased(), host == "open" else {
            return
        }

        // Strip leading slash from comps.path if present
        var rawFolderPath = comps.path
        if rawFolderPath.hasPrefix("/") {
            rawFolderPath.removeFirst()
        }
        let folderPath = rawFolderPath.isEmpty ? nil : decodeAndExpandTilde(rawFolderPath)

        // Extract workspaceName from ?workspace= param
        let workspaceName = comps.queryItems?
            .filter { $0.name == "workspace" }
            .compactMap { $0.value?.trimmingCharacters(in: .whitespaces) }
            .last

        // Extract fileList from ?files= param(s)
        let fileList: [String] = comps.queryItems?
            .filter { $0.name == "files" }
            .compactMap(\.value)
            .flatMap { $0.split(separator: ",").map { String($0).trimmingCharacters(in: .whitespaces) } }
            .map { decodeAndExpandTilde($0) }
            ?? []

        // Concatenate multiple prompt= params with spaces
        let promptParts = comps.queryItems?
            .filter { $0.name == "prompt" }
            .compactMap { $0.value?.removingPercentEncoding }
            ?? []
        let promptText = promptParts.joined(separator: " ").trimmingCharacters(in: .whitespacesAndNewlines)
        let finalPrompt = promptText.isEmpty ? nil : promptText

        /// Parse focus, ephemeral, persist flags
        func boolFromQuery(_ name: String) -> Bool? {
            guard let val = comps.queryItems?.first(where: { $0.name == name })?.value else {
                return nil
            }
            let lower = val.lowercased()
            if lower == "true" || lower == "1" { return true }
            if lower == "false" || lower == "0" { return false }
            return nil
        }
        let focusFlag = boolFromQuery("focus")
        let ephemeralFlag = boolFromQuery("ephemeral")
        let persistFlag = boolFromQuery("persist")

        // Build an AppCommand
        let command = AppCommand(
            workspaceName: workspaceName,
            fileList: fileList,
            promptText: finalPrompt,
            folderPath: folderPath,
            newPrompt: nil,
            focus: focusFlag,
            ephemeral: ephemeralFlag,
            persist: persistFlag
        )

        // If we want to focus an existing window for the same folderPath, do that
        if focusFlag == true, let folderPath {
            if let wsManager = windowStatesManager,
               let existingWindow = wsManager.findWindowState(forFolderPath: folderPath),
               existingWindow !== self
            {
                NSApplication.shared.activate(ignoringOtherApps: true)
                existingWindow.focusWindowIfPossible()
                existingWindow.enqueueCommand(command)
                return
            }
        }

        enqueueCommand(command)
    }

    @MainActor
    private func handleCommand(_ command: AppCommand) async {
        // Determine ephemeral once at the start
        let shouldBeEphemeral = (command.ephemeral == true || command.persist == false)
        var requestedWorkspaceSwitch = false
        var didSwitchWorkspace = false

        // Apply new prompt if provided
        if let prompt = command.newPrompt {
            // 1. add to the PromptViewModel's storage
            let stored = promptManager.addStoredPrompt(
                title: prompt.title,
                content: prompt.content
            )
            // 2. select it so it appears checked/active
            promptManager.selectNewPrompt(stored)

            // 3. if this window isn't front-most and focus flag was set, focus us
            if command.focus == true {
                NSApplication.shared.activate(ignoringOtherApps: true)
                focusWindowIfPossible()
            }

            // If we only have a prompt command with no other parameters, we're done
            if command.folderPath == nil, command.workspaceName == nil,
               command.fileList.isEmpty, command.promptText == nil
            {
                return
            }
        }

        // If we have a folder path, try to open or create a workspace for it
        if let folderPath = command.folderPath, !folderPath.isEmpty {
            let folderURL = URL(fileURLWithPath: folderPath).standardizedFileURL
            var isDir: ObjCBool = false

            if !FileManager.default.fileExists(atPath: folderURL.path, isDirectory: &isDir) || !isDir.boolValue {
                // Not a valid directory
                return
            }

            // Try to find an existing workspace referencing this folder
            if let existingWorkspace = workspaceManager.workspaces.first(where: { ws in
                ws.repoPaths.contains { repoPath in
                    let repoURL = URL(fileURLWithPath: (repoPath as NSString).expandingTildeInPath)
                        .standardizedFileURL
                    return repoURL == folderURL
                }
            }) {
                // If ephemeral == true, mark existing workspace ephemeral (edge case)
                if shouldBeEphemeral {
                    if let index = workspaceManager.workspaces.firstIndex(where: { $0.id == existingWorkspace.id }) {
                        workspaceManager.workspaces[index].isEphemeral = true
                    }
                }

                // If focus == true, attempt to bring up an existing window
                if command.focus == true {
                    if let wsManager = windowStatesManager,
                       let existingWindow = wsManager.findWindowState(showing: existingWorkspace.id)
                    {
                        NSApplication.shared.activate(ignoringOtherApps: true)
                        existingWindow.focusWindowIfPossible()
                        return
                    }
                }

                // Switch to the existing workspace in this window
                requestedWorkspaceSwitch = true
                let result = await workspaceManager.requestWorkspaceSwitch(to: existingWorkspace, saveState: true)
                didSwitchWorkspace = result.didSwitch
            } else {
                // Create a brand-new workspace
                let nameGuess = folderURL.lastPathComponent
                let workspaceName = workspaceManager.uniqueWorkspaceName(baseName: nameGuess)

                // Pass ephemeral to createWorkspace
                let newWS = workspaceManager.createWorkspace(
                    name: workspaceName,
                    repoPaths: [folderURL.path],
                    ephemeral: shouldBeEphemeral
                )
                requestedWorkspaceSwitch = true
                let result = await workspaceManager.requestWorkspaceSwitch(to: newWS, saveState: true)
                didSwitchWorkspace = result.didSwitch
            }
        } else if let workspaceName = command.workspaceName, !workspaceName.isEmpty {
            // Look for an existing workspace by name
            if let existing = workspaceManager.workspaces.first(where: { $0.name == workspaceName }) {
                // If ephemeral == true, mark that workspace ephemeral
                if shouldBeEphemeral {
                    if let index = workspaceManager.workspaces.firstIndex(where: { $0.id == existing.id }) {
                        workspaceManager.workspaces[index].isEphemeral = true
                    }
                }

                // If focus == true, attempt to bring up existing window
                if command.focus == true {
                    if let wsManager = windowStatesManager,
                       let existingWindow = wsManager.findWindowState(showing: existing.id)
                    {
                        NSApplication.shared.activate(ignoringOtherApps: true)
                        existingWindow.focusWindowIfPossible()
                        return
                    }
                }

                requestedWorkspaceSwitch = true
                let result = await workspaceManager.requestWorkspaceSwitch(to: existing, saveState: true)
                didSwitchWorkspace = result.didSwitch
            } else {
                // Create a new workspace by name
                let newWS = workspaceManager.createWorkspace(
                    name: workspaceName,
                    repoPaths: [],
                    ephemeral: shouldBeEphemeral
                )
                requestedWorkspaceSwitch = true
                let result = await workspaceManager.requestWorkspaceSwitch(to: newWS, saveState: true)
                didSwitchWorkspace = result.didSwitch
            }
        }

        // If we now have an active workspace, apply file selection, prompt text, etc.
        if requestedWorkspaceSwitch, !didSwitchWorkspace {
            return
        }
        guard workspaceManager.activeWorkspace != nil else {
            return
        }

        if !command.fileList.isEmpty {
            await workspaceFilesViewModel.selectFiles(withPaths: command.fileList)
        }

        if let prompt = command.promptText, !prompt.isEmpty {
            promptManager.promptText = prompt
        }

        // If focus == true and we haven't switched to another window yet, bring ourselves front
        if command.focus == true {
            NSApplication.shared.activate(ignoringOtherApps: true)
            focusWindowIfPossible()
        }
    }

    // Previous helper methods were refactored into the comprehensive handleCommand method

    // MARK: - Window ID Management

    /// Returns the ID of the most recently created window
    static func latestWindowID() -> Int {
        windowCounter
    }

    // MARK: - Teardown

    func tearDown() async {
        beginClose()
        await promptManager.gitViewModel.shutdownForWindowClose()

        let isAppTermination = WindowStatesManager.shared.isTerminating
        #if DEBUG
            agentChatStressHarness?.pause()
        #endif

        // Optional: persist window settings to workspace defaults if auto-persist is enabled
        if !isAppTermination, UserDefaults.standard.bool(forKey: "autoPersistWindowSettings") {
            await MainActor.run {
                settingsManager.commitAllVisitedWorkspaces()
            }
        }

        // App-level termination already coordinates agent/session and MCP shutdown.
        // Skip duplicate per-window teardown work on quit so close latency stays bounded.
        if isAppTermination {
            aiQueriesService.cancelQuery()
            return
        }

        await workspaceManager.cancelActiveSessions()
        await agentModeViewModel.prepareForWindowClose()
        WorkspaceApprovalManager.shared.cancelPending(forWindowID: windowID)

        // Stop the local MCP server
        await mcpServer.stopServer()

        // Release per-window codemap work before the closed window can contend with later windows.
        await workspaceFilesViewModel.cancelAllScans()

        // Cancel any ongoing AI query
        aiQueriesService.cancelQuery()

        // IMPORTANT:
        // During window close / app termination, avoid mutating UI-observed state
        // (file selections, prompt text, root folders, etc.). That churn can crash SwiftUI
        // while NSHostingView is updating constraints / tearing down.
        guard !shouldSuppressObservationSideEffects else {
            return
        }

        // Clear workspace files UI adapter state
        await workspaceFilesViewModel.clearSelection()
        for rootFolder in workspaceFilesViewModel.rootFolders {
            await workspaceFilesViewModel.unloadRootFolder(rootFolder)
        }

        // Clear prompt manager state
        await MainActor.run {
            promptManager.clearPrompt()
        }
    }

    /// Attempts to bring this window to the front if possible
    func focusWindowIfPossible() {
        // Since WindowState is not an NSWindow, we can only activate the app
        // The window itself will be brought forward by the system
        NSApplication.shared.activate(ignoringOtherApps: true)
    }

    @discardableResult
    func revealPendingInteraction(tabID: UUID, surface: PendingInteractionSurface) async -> Bool {
        guard let window = nsWindow else { return false }

        NSApp.activate(ignoringOtherApps: true)
        window.makeKeyAndOrderFront(nil)

        _ = surface

        if promptManager.activeComposeTabID != tabID {
            await promptManager.switchComposeTab(tabID)
        }

        return true
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
        pendingWindowTitleUpdateTask?.cancel()
        pendingFocusUpdateTask?.cancel()
        pendingFocusSideEffectsTask?.cancel()
        // Do not call unregisterWindowState here; deinit is nonisolated and
        // you can't hop to @MainActor. Unregistration happens in ContentView onDisappear.
    }
}