Neon-Vision-Editor/Neon Vision Editor/UI/ContentView.swift

// ContentView.swift
// Main SwiftUI container for Neon Vision Editor. Hosts the single-document editor UI,
// toolbar actions, AI integration, syntax highlighting, line numbers, and sidebar TOC.

///MARK: - Imports
import SwiftUI
import Foundation
import Observation
import UniformTypeIdentifiers
import OSLog
import Dispatch
#if os(macOS)
import AppKit
#elseif canImport(UIKit)
import UIKit
#endif
#if USE_FOUNDATION_MODELS && canImport(FoundationModels)
import FoundationModels
#endif

#if os(macOS)
private final class WindowCloseConfirmationDelegate: NSObject, NSWindowDelegate {
    nonisolated(unsafe) weak var forwardedDelegate: NSWindowDelegate?
    var shouldConfirm: (() -> Bool)?
    var hasDirtyTabs: (() -> Bool)?
    var saveAllDirtyTabs: (() -> Bool)?
    var dialogTitle: (() -> String)?
    var dialogMessage: (() -> String)?

    private var isPromptInFlight = false
    private var allowNextClose = false

    nonisolated override func responds(to selector: Selector!) -> Bool {
        super.responds(to: selector) || (forwardedDelegate?.responds(to: selector) ?? false)
    }

    nonisolated override func forwardingTarget(for selector: Selector!) -> Any? {
        if forwardedDelegate?.responds(to: selector) == true {
            return forwardedDelegate
        }
        return super.forwardingTarget(for: selector)
    }

    func windowShouldClose(_ sender: NSWindow) -> Bool {
        if allowNextClose {
            allowNextClose = false
            return forwardedDelegate?.windowShouldClose?(sender) ?? true
        }

        let needsPrompt = shouldConfirm?() == true && hasDirtyTabs?() == true
        if !needsPrompt {
            return forwardedDelegate?.windowShouldClose?(sender) ?? true
        }

        if isPromptInFlight {
            return false
        }
        isPromptInFlight = true

        let alert = NSAlert()
        alert.messageText = dialogTitle?() ?? "Save changes before closing?"
        alert.informativeText = dialogMessage?() ?? "One or more tabs have unsaved changes."
        alert.alertStyle = .warning
        alert.addButton(withTitle: "Save")
        alert.addButton(withTitle: "Don't Save")
        alert.addButton(withTitle: "Cancel")
        alert.beginSheetModal(for: sender) { [weak self] response in
            guard let self else { return }
            self.isPromptInFlight = false
            switch response {
            case .alertFirstButtonReturn:
                if self.saveAllDirtyTabs?() == true {
                    self.allowNextClose = true
                    sender.performClose(nil)
                }
            case .alertSecondButtonReturn:
                self.allowNextClose = true
                sender.performClose(nil)
            default:
                break
            }
        }
        return false
    }
}
#endif


// Utility: quick width calculation for strings with a given font (AppKit-based)
extension String {
#if os(macOS)
    func width(usingFont font: NSFont) -> CGFloat {
        let attributes = [NSAttributedString.Key.font: font]
        let size = (self as NSString).size(withAttributes: attributes)
        return size.width
    }
#endif
}

///MARK: - Root View
//Manages the editor area, toolbar, popovers, and bridges to the view model for file I/O and metrics.
struct ContentView: View {
    enum StartupBehavior {
        case standard
        case forceBlankDocument
        case safeMode
    }

    enum ProjectNavigatorPlacement: String, CaseIterable, Identifiable {
        case leading
        case trailing

        var id: String { rawValue }
    }

    enum PerformancePreset: String, CaseIterable, Identifiable {
        case balanced
        case largeFiles
        case battery

        var id: String { rawValue }
    }

    enum DelimitedViewMode: String, CaseIterable, Identifiable {
        case table
        case text

        var id: String { rawValue }
    }

    enum ProjectSidebarCreationKind: String {
        case file
        case folder

        var title: String {
            switch self {
            case .file:
                return NSLocalizedString("New File", comment: "Project sidebar creation title for files")
            case .folder:
                return NSLocalizedString("New Folder", comment: "Project sidebar creation title for folders")
            }
        }

        var namePlaceholder: String {
            switch self {
            case .file:
                return NSLocalizedString("File name", comment: "Project sidebar file name placeholder")
            case .folder:
                return NSLocalizedString("Folder name", comment: "Project sidebar folder name placeholder")
            }
        }
    }

    struct DelimitedTableSnapshot: Sendable {
        let header: [String]
        let rows: [[String]]
        let totalRows: Int
        let displayedRows: Int
        let truncated: Bool
    }

    struct DelimitedTableParseError: LocalizedError {
        let message: String
        var errorDescription: String? { message }
    }

    let startupBehavior: StartupBehavior
    let safeModeMessage: String?

    init(startupBehavior: StartupBehavior = .standard, safeModeMessage: String? = nil) {
        self.startupBehavior = startupBehavior
        self.safeModeMessage = safeModeMessage
    }

    private enum EditorPerformanceThresholds {
        static let largeFileBytes = 12_000_000
        static let largeFileBytesHTMLCSV = 4_000_000
        static let largeFileBytesMobile = 8_000_000
        static let largeFileBytesHTMLCSVMobile = 3_000_000
        static let heavyFeatureUTF16Length = 450_000
        static let largeFileLineBreaks = 40_000
        static let largeFileLineBreaksHTMLCSV = 15_000
        static let largeFileLineBreaksMobile = 25_000
        static let largeFileLineBreaksHTMLCSVMobile = 10_000
    }
    private static let completionSignposter = OSSignposter(subsystem: "h3p.Neon-Vision-Editor", category: "InlineCompletion")

    private struct CompletionCacheEntry {
        let suggestion: String
        let createdAt: Date
    }

    private struct SavedDraftTabSnapshot: Codable {
        let name: String
        let content: String
        let language: String
        let fileURLString: String?
    }

    private struct SavedDraftSnapshot: Codable {
        let tabs: [SavedDraftTabSnapshot]
        let selectedIndex: Int?
        let createdAt: Date
    }

    // Environment-provided view model and theme/error bindings
    @Environment(EditorViewModel.self) var viewModel
    @EnvironmentObject private var supportPurchaseManager: SupportPurchaseManager
    @EnvironmentObject var appUpdateManager: AppUpdateManager
    @Environment(\.colorScheme) var colorScheme
#if os(iOS)
    @Environment(\.horizontalSizeClass) var horizontalSizeClass
#endif
#if os(macOS)
    @Environment(\.openWindow) var openWindow
    @Environment(\.openSettings) var openSettingsAction
#endif
    @Environment(\.showGrokError) var showGrokError
    @Environment(\.grokErrorMessage) var grokErrorMessage

    // Single-document fallback state (used when no tab model is selected)
    @AppStorage("SelectedAIModel") private var selectedModelRaw: String = AIModel.appleIntelligence.rawValue
    @State var singleContent: String = ""
    @State var singleLanguage: String = "plain"
    @State var caretStatus: String = "Ln 1, Col 1"
    @AppStorage("SettingsEditorFontSize") var editorFontSize: Double = 14
    @AppStorage("SettingsEditorFontName") var editorFontName: String = ""
    @AppStorage("SettingsLineHeight") var editorLineHeight: Double = 1.0
    @AppStorage("SettingsShowLineNumbers") var showLineNumbers: Bool = true
    @AppStorage("SettingsHighlightCurrentLine") var highlightCurrentLine: Bool = false
    @AppStorage("SettingsHighlightMatchingBrackets") var highlightMatchingBrackets: Bool = false
    @AppStorage("SettingsShowScopeGuides") var showScopeGuides: Bool = false
    @AppStorage("SettingsHighlightScopeBackground") var highlightScopeBackground: Bool = false
    @AppStorage("SettingsLineWrapEnabled") var settingsLineWrapEnabled: Bool = false
    // Removed showHorizontalRuler and showVerticalRuler AppStorage properties
    @AppStorage("SettingsIndentStyle") var indentStyle: String = "spaces"
    @AppStorage("SettingsIndentWidth") var indentWidth: Int = 4
    @AppStorage("SettingsAutoIndent") var autoIndentEnabled: Bool = true
    @AppStorage("SettingsAutoCloseBrackets") var autoCloseBracketsEnabled: Bool = false
    @AppStorage("SettingsTrimTrailingWhitespace") var trimTrailingWhitespaceEnabled: Bool = false
    @AppStorage("SettingsCompletionEnabled") var isAutoCompletionEnabled: Bool = false
    @AppStorage("SettingsCompletionFromDocument") var completionFromDocument: Bool = false
    @AppStorage("SettingsCompletionFromSyntax") var completionFromSyntax: Bool = false
    @AppStorage("SettingsReopenLastSession") var reopenLastSession: Bool = true
    @AppStorage("SettingsOpenWithBlankDocument") var openWithBlankDocument: Bool = true
    @AppStorage("SettingsConfirmCloseDirtyTab") var confirmCloseDirtyTab: Bool = true
    @AppStorage("SettingsConfirmClearEditor") var confirmClearEditor: Bool = true
    @AppStorage("SettingsActiveTab") var settingsActiveTab: String = "general"
    @AppStorage("SettingsAppearance") var appearance: String = "system"
    @AppStorage("SettingsTemplateLanguage") private var settingsTemplateLanguage: String = "swift"
    @AppStorage("SettingsThemeName") private var settingsThemeName: String = "Neon Glow"
    @AppStorage("SettingsThemeBoldKeywords") private var settingsThemeBoldKeywords: Bool = false
    @AppStorage("SettingsThemeItalicComments") private var settingsThemeItalicComments: Bool = false
    @AppStorage("SettingsThemeUnderlineLinks") private var settingsThemeUnderlineLinks: Bool = false
    @AppStorage("SettingsThemeBoldMarkdownHeadings") private var settingsThemeBoldMarkdownHeadings: Bool = false
    @State var lastProviderUsed: String = "Apple"
    @State private var highlightRefreshToken: Int = 0
    @State var editorExternalMutationRevision: Int = 0

    // Persisted API tokens for external providers
    @State var grokAPIToken: String = ""
    @State var openAIAPIToken: String = ""
    @State var geminiAPIToken: String = ""
    @State var anthropicAPIToken: String = ""

    // Debounce/cancellation handles for inline completion
    @State private var completionDebounceTask: Task<Void, Never>?
    @State private var completionTask: Task<Void, Never>?
    @State private var lastCompletionTriggerSignature: String = ""
    @State private var isApplyingCompletion: Bool = false
    @State private var completionCache: [String: CompletionCacheEntry] = [:]
    @State private var pendingHighlightRefresh: DispatchWorkItem?
#if os(iOS)
    @AppStorage("EnableTranslucentWindow") var enableTranslucentWindow: Bool = true
#else
    @AppStorage("EnableTranslucentWindow") var enableTranslucentWindow: Bool = false
#endif
#if os(iOS)
    @State private var previousKeyboardAccessoryVisibility: Bool? = nil
    @State var markdownPreviewSheetDetent: PresentationDetent = .medium
#endif
#if os(macOS)
    @AppStorage("SettingsMacTranslucencyMode") private var macTranslucencyModeRaw: String = "balanced"
#endif

    @State var showFindReplace: Bool = false
    @State var showSettingsSheet: Bool = false
    @State var showUpdateDialog: Bool = false
    @State var findQuery: String = ""
    @State var replaceQuery: String = ""
    @State var findUsesRegex: Bool = false
    @State var findCaseSensitive: Bool = false
    @State var findStatusMessage: String = ""
    @State var findMatchCount: Int = 0
    @State var iOSFindCursorLocation: Int = 0
    @State var iOSLastFindFingerprint: String = ""
    @State var showProjectStructureSidebar: Bool = false
    @State var showCompactSidebarSheet: Bool = false
    @State var showCompactProjectSidebarSheet: Bool = false
    @State var projectRootFolderURL: URL? = nil
    @State var projectTreeNodes: [ProjectTreeNode] = []
    @State var projectTreeRefreshGeneration: Int = 0
    @State var projectTreeRevealURL: URL? = nil
    @AppStorage("SettingsShowSupportedProjectFilesOnly") var showSupportedProjectFilesOnly: Bool = true
    @AppStorage("SettingsShowInvisibleCharacters") var showInvisibleCharacters: Bool = false
    @State var projectOverrideIndentWidth: Int? = nil
    @State var projectOverrideLineWrapEnabled: Bool? = nil
    @State var showProjectFolderPicker: Bool = false
    @State var projectFolderSecurityURL: URL? = nil
    @State var pendingCloseTabID: UUID? = nil
    @State var showUnsavedCloseDialog: Bool = false
    @State var showCloseAllTabsDialog: Bool = false
    @State private var showExternalConflictDialog: Bool = false
    @State private var showRemoteSaveIssueDialog: Bool = false
    @State private var showExternalConflictCompareSheet: Bool = false
    @State private var externalConflictCompareSnapshot: EditorViewModel.ExternalFileComparisonSnapshot?
    @State private var showRemoteConflictCompareSheet: Bool = false
    @State private var remoteConflictCompareSnapshot: EditorViewModel.RemoteConflictComparisonSnapshot?
    @State var showClearEditorConfirmDialog: Bool = false
    @State var showIOSFileImporter: Bool = false
    @State var showIOSFileExporter: Bool = false
    @State var showUnsupportedFileAlert: Bool = false
    @State var unsupportedFileName: String = ""
    @State var showProjectItemCreationPrompt: Bool = false
    @State var projectItemCreationNameDraft: String = ""
    @State var projectItemCreationKind: ProjectSidebarCreationKind = .file
    @State var projectItemCreationParentURL: URL? = nil
    @State var showProjectItemRenamePrompt: Bool = false
    @State var projectItemRenameNameDraft: String = ""
    @State var projectItemRenameSourceURL: URL? = nil
    @State var showProjectItemDeleteConfirmation: Bool = false
    @State var projectItemDeleteTargetURL: URL? = nil
    @State var projectItemDeleteTargetName: String = ""
    @State var showProjectItemOperationErrorAlert: Bool = false
    @State var projectItemOperationErrorMessage: String = ""
    @State var iosExportDocument: PlainTextDocument = PlainTextDocument(text: "")
    @State var iosExportFilename: String = "Untitled.txt"
    @State var iosExportTabID: UUID? = nil
    @State var showMarkdownPDFExporter: Bool = false
    @State var markdownPDFExportDocument: PDFExportDocument = PDFExportDocument()
    @State var markdownPDFExportFilename: String = "Markdown-Preview.pdf"
    @State var markdownPDFExportErrorMessage: String?
    @State var markdownPreviewActionStatusMessage: String = ""
    @State var markdownPreviewActionStatusToken: UUID = UUID()
    @State var showQuickSwitcher: Bool = false
    @State var quickSwitcherQuery: String = ""
    @State var quickSwitcherProjectFileURLs: [URL] = []
    @State var projectFileIndexSnapshot: ProjectFileIndex.Snapshot = .empty
    @State var isProjectFileIndexing: Bool = false
    @State var projectFileIndexRefreshGeneration: Int = 0
    @State var projectFileIndexTask: Task<Void, Never>? = nil
    @State var projectFolderMonitorSource: DispatchSourceFileSystemObject? = nil
    @State var pendingProjectFolderRefreshWorkItem: DispatchWorkItem? = nil
    @State private var quickSwitcherRecentItemIDs: [String] = []
    @State var recentFilesRefreshToken: UUID = UUID()
    @State private var currentSelectionSnapshotText: String = ""
    @State private var codeSnapshotPayload: CodeSnapshotPayload?
    @State var showFindInFiles: Bool = false
    @State var findInFilesQuery: String = ""
    @State var findInFilesCaseSensitive: Bool = false
    @State var findInFilesResults: [FindInFilesMatch] = []
    @State var findInFilesStatusMessage: String = ""
    @State var findInFilesSourceMessage: String = ""
    @State private var findInFilesTask: Task<Void, Never>?
    @State private var statusWordCount: Int = 0
    @State private var statusLineCount: Int = 1
    @State private var wordCountTask: Task<Void, Never>?
    @AppStorage("EditorVimModeEnabled") var vimModeEnabled: Bool = false
    @State var vimInsertMode: Bool = true
    @State var safeModeRecoveryPreparedForNextLaunch: Bool = false
    @State var droppedFileLoadInProgress: Bool = false
    @State var droppedFileProgressDeterminate: Bool = true
    @State var droppedFileLoadProgress: Double = 0
    @State var droppedFileLoadLabel: String = ""
    @State var largeFileModeEnabled: Bool = false
    @SceneStorage("ProjectSidebarWidth") private var projectSidebarWidth: Double = 320
    @State private var projectSidebarResizeStartWidth: CGFloat? = nil
    @State private var delimitedViewMode: DelimitedViewMode = .table
    @State private var delimitedTableSnapshot: DelimitedTableSnapshot? = nil
    @State private var isBuildingDelimitedTable: Bool = false
    @State private var delimitedTableStatus: String = ""
    @State private var delimitedParseTask: Task<Void, Never>? = nil
    @AppStorage("SettingsProjectNavigatorPlacement") var projectNavigatorPlacementRaw: String = ProjectNavigatorPlacement.trailing.rawValue
    @AppStorage("SettingsPerformancePreset") var performancePresetRaw: String = PerformancePreset.balanced.rawValue
    @AppStorage("SettingsLargeFileOpenMode") private var largeFileOpenModeRaw: String = "deferred"
    @AppStorage("SettingsRemoteSessionsEnabled") private var remoteSessionsEnabled: Bool = false
    @AppStorage("SettingsRemotePreparedTarget") private var remotePreparedTarget: String = ""
    @State private var remoteSessionStore = RemoteSessionStore.shared
#if os(iOS)
    @AppStorage("SettingsForceLargeFileMode") var forceLargeFileMode: Bool = false
    @AppStorage("SettingsShowKeyboardAccessoryBarIOS") var showKeyboardAccessoryBarIOS: Bool = false
    @AppStorage("SettingsShowBottomActionBarIOS") var showBottomActionBarIOS: Bool = true
    @AppStorage("SettingsUseLiquidGlassToolbarIOS") var shouldUseLiquidGlass: Bool = true
    @AppStorage("SettingsToolbarIconsBlueIOS") var toolbarIconsBlueIOS: Bool = false
#endif
    @AppStorage("HasSeenWelcomeTourV1") var hasSeenWelcomeTourV1: Bool = false
    @AppStorage("WelcomeTourSeenRelease") var welcomeTourSeenRelease: String = ""
    @AppStorage("AppLaunchCountV1") var appLaunchCount: Int = 0
    @AppStorage("HasShownSupportPromptV1") var hasShownSupportPromptV1: Bool = false
    @State var showWelcomeTour: Bool = false
    @State var showEditorHelp: Bool = false
    @State var showSupportPromptSheet: Bool = false
#if os(macOS)
    @State private var hostWindowNumber: Int? = nil
    @AppStorage("ShowBracketHelperBarMac") var showBracketHelperBarMac: Bool = false
    @AppStorage("SettingsToolbarSymbolsColorMac") var toolbarSymbolsColorMacRaw: String = "blue"
    @State private var windowCloseConfirmationDelegate: WindowCloseConfirmationDelegate? = nil
#endif
    @State var showMarkdownPreviewPane: Bool = false
#if os(macOS)
    @AppStorage("MarkdownPreviewTemplateMac") var markdownPreviewTemplateRaw: String = "default"
#elseif os(iOS)
    @AppStorage("MarkdownPreviewTemplateIOS") var markdownPreviewTemplateRaw: String = "default"
#endif
    @AppStorage("MarkdownPreviewBackgroundStyle") var markdownPreviewBackgroundStyleRaw: String = "automatic"
    @AppStorage("MarkdownPreviewPDFExportMode") var markdownPDFExportModeRaw: String = "paginated-fit"
    @State private var showLanguageSetupPrompt: Bool = false
    @State private var languagePromptSelection: String = "plain"
    @State private var languagePromptInsertTemplate: Bool = false
    @State private var showLanguageSearchSheet: Bool = false
    @State private var languageSearchQuery: String = ""
    @State private var whitespaceInspectorMessage: String? = nil
    @State private var didApplyStartupBehavior: Bool = false
    @State private var didRunInitialWindowLayoutSetup: Bool = false
    @State private var pendingLargeFileModeReevaluation: DispatchWorkItem? = nil
    @State private var recoverySnapshotIdentifier: String = UUID().uuidString
    @State private var lastCaretLocation: Int = 0
    @State private var sessionCaretByFileURL: [String: Int] = [:]
#if os(macOS)
    @State private var isProjectSidebarResizeHandleHovered: Bool = false
#endif
    private let quickSwitcherRecentsDefaultsKey = "QuickSwitcherRecentItemsV1"

#if USE_FOUNDATION_MODELS && canImport(FoundationModels)
    var appleModelAvailable: Bool { true }
#else
    var appleModelAvailable: Bool { false }
#endif

    var activeProviderName: String {
        let trimmed = lastProviderUsed.trimmingCharacters(in: .whitespacesAndNewlines)
        if trimmed.isEmpty || trimmed == "Apple" {
            return selectedModel.displayName
        }
        return trimmed
    }

    private var projectNavigatorPlacement: ProjectNavigatorPlacement {
        ProjectNavigatorPlacement(rawValue: projectNavigatorPlacementRaw) ?? .trailing
    }

    private var performancePreset: PerformancePreset {
        PerformancePreset(rawValue: performancePresetRaw) ?? .balanced
    }

    private var minimumProjectSidebarWidth: CGFloat { 320 }
    private var maximumProjectSidebarWidth: CGFloat { 520 }

    private var clampedProjectSidebarWidth: CGFloat {
        let clamped = min(max(projectSidebarWidth, Double(minimumProjectSidebarWidth)), Double(maximumProjectSidebarWidth))
        return CGFloat(clamped)
    }

    private var isDelimitedFileLanguage: Bool {
        let lower = currentLanguage.lowercased()
        return lower == "csv" || lower == "tsv"
    }

    private var delimitedSeparator: Character {
        currentLanguage.lowercased() == "tsv" ? "\t" : ","
    }

    private var shouldShowDelimitedTable: Bool {
        isDelimitedFileLanguage && delimitedViewMode == .table
    }
#if os(macOS)
    private enum MacTranslucencyMode: String {
        case subtle
        case balanced
        case vibrant

        var material: Material {
            switch self {
            case .subtle, .balanced:
                return .thickMaterial
            case .vibrant:
                return .regularMaterial
            }
        }

        var opacity: Double {
            switch self {
            case .subtle: return 0.84
            case .balanced: return 0.76
            case .vibrant: return 0.68
            }
        }

        var toolbarOpacity: Double {
            switch self {
            case .subtle: return 0.72
            case .balanced: return 0.64
            case .vibrant: return 0.56
            }
        }
    }

    private var macTranslucencyMode: MacTranslucencyMode {
        MacTranslucencyMode(rawValue: macTranslucencyModeRaw) ?? .balanced
    }

    private let bracketHelperTokens: [String] = ["(", ")", "{", "}", "[", "]", "<", ">", "'", "\"", "`", "()", "{}", "[]", "\"\"", "''"]
    private var macUnifiedTranslucentMaterialStyle: AnyShapeStyle {
        AnyShapeStyle(macTranslucencyMode.material.opacity(macTranslucencyMode.opacity))
    }
    private var macSolidSurfaceColor: Color {
        currentEditorTheme(colorScheme: colorScheme).background
    }
    private var macChromeBackgroundStyle: AnyShapeStyle {
        if enableTranslucentWindow {
            return macUnifiedTranslucentMaterialStyle
        }
        return AnyShapeStyle(macSolidSurfaceColor)
    }

    private var macToolbarBackgroundStyle: AnyShapeStyle {
        if enableTranslucentWindow {
            return AnyShapeStyle(macTranslucencyMode.material.opacity(macTranslucencyMode.toolbarOpacity))
        }
        return AnyShapeStyle(macSolidSurfaceColor)
    }
#elseif os(iOS)
    var primaryGlassMaterial: Material { colorScheme == .dark ? .regularMaterial : .ultraThinMaterial }
    var toolbarFallbackColor: Color {
        colorScheme == .dark ? Color.black.opacity(0.34) : Color.white.opacity(0.86)
    }
    private var iOSNonTranslucentSurfaceColor: Color {
        currentEditorTheme(colorScheme: colorScheme).background
    }
    private var useIOSUnifiedSolidSurfaces: Bool {
        !enableTranslucentWindow
    }
    var toolbarDensityScale: CGFloat { 1.0 }
    var toolbarDensityOpacity: Double { 1.0 }

    private var canShowMarkdownPreviewOnCurrentDevice: Bool {
        horizontalSizeClass == .regular
    }
#endif

    private var editorSurfaceBackgroundStyle: AnyShapeStyle {
#if os(macOS)
        if enableTranslucentWindow {
            return macUnifiedTranslucentMaterialStyle
        }
        return AnyShapeStyle(macSolidSurfaceColor)
#else
        if useIOSUnifiedSolidSurfaces {
            return AnyShapeStyle(iOSNonTranslucentSurfaceColor)
        }
        return enableTranslucentWindow ? AnyShapeStyle(.ultraThinMaterial) : AnyShapeStyle(Color.clear)
#endif
    }

    var canShowMarkdownPreviewPane: Bool {
#if os(iOS)
        true
#else
        true
#endif
    }

    private var canShowMarkdownPreviewSplitPane: Bool {
#if os(iOS)
        canShowMarkdownPreviewOnCurrentDevice
#else
        true
#endif
    }

#if os(iOS)
    private var shouldPresentMarkdownPreviewSheetOnIPhone: Bool {
        UIDevice.current.userInterfaceIdiom == .phone &&
        showMarkdownPreviewPane &&
        currentLanguage == "markdown" &&
        !brainDumpLayoutEnabled
    }

    private var markdownPreviewSheetPresentationBinding: Binding<Bool> {
        Binding(
            get: { shouldPresentMarkdownPreviewSheetOnIPhone },
            set: { isPresented in
                if !isPresented {
                    showMarkdownPreviewPane = false
                }
            }
        )
    }
#endif

    private var settingsSheetDetents: Set<PresentationDetent> {
#if os(iOS)
        if UIDevice.current.userInterfaceIdiom == .pad {
            return [.fraction(0.985)]
        }
        return [.large]
#else
        return [.large]
#endif
    }

#if os(macOS)
    private var macTabBarStripHeight: CGFloat { 36 }
#endif

    private var useIPhoneUnifiedTopHost: Bool {
#if os(iOS)
        UIDevice.current.userInterfaceIdiom == .phone
#else
        false
#endif
    }

    private var tabBarLeadingPadding: CGFloat {
#if os(iOS)
        if UIDevice.current.userInterfaceIdiom == .pad {
            // Keep tabs clear of iPad window controls in narrow/multitasking layouts.
            return horizontalSizeClass == .compact ? 112 : 96
        }
#endif
        return 10
    }

    var selectedModel: AIModel {
        get { AIModel(rawValue: selectedModelRaw) ?? .appleIntelligence }
        set { selectedModelRaw = newValue.rawValue }
    }

    private func promptForGrokTokenIfNeeded() -> Bool {
        if !grokAPIToken.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty { return true }
#if os(macOS)
        let alert = NSAlert()
        alert.messageText = "Grok API Token Required"
        alert.informativeText = "Enter your Grok API token to enable suggestions. You can obtain this from your Grok account."
        alert.alertStyle = .informational
        alert.addButton(withTitle: "Save")
        alert.addButton(withTitle: "Cancel")
        let input = NSSecureTextField(frame: NSRect(x: 0, y: 0, width: 280, height: 24))
        input.placeholderString = "sk-..."
        alert.accessoryView = input
        let response = alert.runModal()
        if response == .alertFirstButtonReturn {
            let token = input.stringValue.trimmingCharacters(in: .whitespacesAndNewlines)
            if token.isEmpty { return false }
            grokAPIToken = token
            SecureTokenStore.setToken(token, for: .grok)
            return true
        }
#endif
        return false
    }

    private func promptForOpenAITokenIfNeeded() -> Bool {
        if !openAIAPIToken.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty { return true }
#if os(macOS)
        let alert = NSAlert()
        alert.messageText = "OpenAI API Token Required"
        alert.informativeText = "Enter your OpenAI API token to enable suggestions."
        alert.alertStyle = .informational
        alert.addButton(withTitle: "Save")
        alert.addButton(withTitle: "Cancel")
        let input = NSSecureTextField(frame: NSRect(x: 0, y: 0, width: 280, height: 24))
        input.placeholderString = "sk-..."
        alert.accessoryView = input
        let response = alert.runModal()
        if response == .alertFirstButtonReturn {
            let token = input.stringValue.trimmingCharacters(in: .whitespacesAndNewlines)
            if token.isEmpty { return false }
            openAIAPIToken = token
            SecureTokenStore.setToken(token, for: .openAI)
            return true
        }
#endif
        return false
    }

    private func promptForGeminiTokenIfNeeded() -> Bool {
        if !geminiAPIToken.isEmpty { return true }
#if os(macOS)
        let alert = NSAlert()
        alert.messageText = "Gemini API Key Required"
        alert.informativeText = "Enter your Gemini API key to enable suggestions."
        alert.alertStyle = .informational
        alert.addButton(withTitle: "Save")
        alert.addButton(withTitle: "Cancel")
        let input = NSSecureTextField(frame: NSRect(x: 0, y: 0, width: 280, height: 24))
        input.placeholderString = "AIza..."
        alert.accessoryView = input
        let response = alert.runModal()
        if response == .alertFirstButtonReturn {
            let token = input.stringValue.trimmingCharacters(in: .whitespacesAndNewlines)
            if token.isEmpty { return false }
            geminiAPIToken = token
            SecureTokenStore.setToken(token, for: .gemini)
            return true
        }
#endif
        return false
    }

    private func promptForAnthropicTokenIfNeeded() -> Bool {
        if !anthropicAPIToken.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty { return true }
#if os(macOS)
        let alert = NSAlert()
        alert.messageText = "Anthropic API Token Required"
        alert.informativeText = "Enter your Anthropic API token to enable suggestions."
        alert.alertStyle = .informational
        alert.addButton(withTitle: "Save")
        alert.addButton(withTitle: "Cancel")
        let input = NSSecureTextField(frame: NSRect(x: 0, y: 0, width: 280, height: 24))
        input.placeholderString = "sk-ant-..."
        alert.accessoryView = input
        let response = alert.runModal()
        if response == .alertFirstButtonReturn {
            let token = input.stringValue.trimmingCharacters(in: .whitespacesAndNewlines)
            if token.isEmpty { return false }
            anthropicAPIToken = token
            SecureTokenStore.setToken(token, for: .anthropic)
            return true
        }
#endif
        return false
    }

    #if os(macOS)
    @MainActor
    private func performInlineCompletion(for textView: NSTextView) {
        completionTask?.cancel()
        completionTask = Task(priority: .utility) {
            await performInlineCompletionAsync(for: textView)
        }
    }

    @MainActor
    private func performInlineCompletionAsync(for textView: NSTextView) async {
        let completionInterval = Self.completionSignposter.beginInterval("inline_completion")
        defer { Self.completionSignposter.endInterval("inline_completion", completionInterval) }

        let sel = textView.selectedRange()
        guard sel.length == 0 else { return }
        let loc = sel.location
        guard loc > 0, loc <= (textView.string as NSString).length else { return }
        let nsText = textView.string as NSString
        if Task.isCancelled { return }
        if shouldThrottleHeavyEditorFeatures(in: nsText) { return }

        let prevChar = nsText.substring(with: NSRange(location: loc - 1, length: 1))
        var nextChar: String? = nil
        if loc < nsText.length {
            nextChar = nsText.substring(with: NSRange(location: loc, length: 1))
        }

        // Auto-close braces/brackets/parens if not already closed
        let pairs: [String: String] = ["{": "}", "(": ")", "[": "]"]
        if let closing = pairs[prevChar] {
            if nextChar != closing {
                // Insert closing and move caret back between pair
                let insertion = closing
                textView.insertText(insertion, replacementRange: sel)
                textView.setSelectedRange(NSRange(location: loc, length: 0))
                return
            }
        }

        // If previous char is '{' and language is swift, javascript, c, or cpp, insert code block scaffold
        if prevChar == "{" && ["swift", "javascript", "c", "cpp"].contains(currentLanguage) {
            // Get current line indentation
            let fullText = textView.string as NSString
            let lineRange = fullText.lineRange(for: NSRange(location: loc - 1, length: 0))
            let lineText = fullText.substring(with: lineRange)
            let indentPrefix = lineText.prefix(while: { $0 == " " || $0 == "\t" })

            let indentString = String(indentPrefix)
            let indentLevel = indentString.count
            let indentSpaces = "    " // 4 spaces

            // Build scaffold string
            let scaffold = "\n\(indentString)\(indentSpaces)\n\(indentString)}"

            // Insert scaffold at caret position
            textView.insertText(scaffold, replacementRange: NSRange(location: loc, length: 0))

            // Move caret to indented empty line
            let newCaretLocation = loc + 1 + indentLevel + indentSpaces.count
            textView.setSelectedRange(NSRange(location: newCaretLocation, length: 0))
            return
        }

        // Prefer cheap local matches before model-backed completion.
        let doc = textView.string
        let nsDoc = doc as NSString
        if let localSuggestion = CompletionHeuristics.localSuggestion(
            in: nsDoc,
            caretLocation: loc,
            language: currentLanguage,
            includeDocumentWords: completionFromDocument,
            includeSyntaxKeywords: completionFromSyntax
        ) {
            applyInlineSuggestion(localSuggestion, textView: textView, selection: sel)
            return
        }

        // Limit completion context by both recent lines and UTF-16 length for lower latency.
        let tokenContext = CompletionHeuristics.tokenContext(in: nsDoc, caretLocation: loc)
        let contextPrefix = completionContextPrefix(in: nsDoc, caretLocation: loc)
        let cacheKey = completionCacheKey(prefix: contextPrefix, language: currentLanguage, caretLocation: loc)

        if let cached = cachedCompletion(for: cacheKey) {
            Self.completionSignposter.emitEvent("completion_cache_hit")
            applyInlineSuggestion(cached, textView: textView, selection: sel)
            return
        }

        let modelInterval = Self.completionSignposter.beginInterval("model_completion")
        let suggestion = await generateModelCompletion(prefix: contextPrefix, language: currentLanguage)
        Self.completionSignposter.endInterval("model_completion", modelInterval)
        if Task.isCancelled { return }
        let sanitizedSuggestion = CompletionHeuristics.sanitizeModelSuggestion(
            suggestion,
            currentTokenPrefix: tokenContext.prefix,
            nextDocumentText: tokenContext.nextDocumentText
        )
        storeCompletionInCache(sanitizedSuggestion, for: cacheKey)
        applyInlineSuggestion(sanitizedSuggestion, textView: textView, selection: sel)
    }

    private func completionContextPrefix(in nsDoc: NSString, caretLocation: Int, maxUTF16: Int = 3000, maxLines: Int = 120) -> String {
        let startByChars = max(0, caretLocation - maxUTF16)

        var cursor = caretLocation
        var seenLines = 0
        while cursor > 0 && seenLines < maxLines {
            let searchRange = NSRange(location: 0, length: cursor)
            let found = nsDoc.range(of: "\n", options: .backwards, range: searchRange)
            if found.location == NSNotFound {
                cursor = 0
                break
            }
            cursor = found.location
            seenLines += 1
        }
        let startByLines = cursor
        let start = max(startByChars, startByLines)
        return nsDoc.substring(with: NSRange(location: start, length: caretLocation - start))
    }

    private func completionCacheKey(prefix: String, language: String, caretLocation: Int) -> String {
        let normalizedPrefix = String(prefix.suffix(320))
        var hasher = Hasher()
        hasher.combine(language)
        hasher.combine(caretLocation / 32)
        hasher.combine(normalizedPrefix)
        return "\(language):\(caretLocation / 32):\(hasher.finalize())"
    }

    private func cachedCompletion(for key: String) -> String? {
        pruneCompletionCacheIfNeeded()
        guard let entry = completionCache[key] else { return nil }
        if Date().timeIntervalSince(entry.createdAt) > 20 {
            completionCache.removeValue(forKey: key)
            return nil
        }
        return entry.suggestion
    }

    private func storeCompletionInCache(_ suggestion: String, for key: String) {
        completionCache[key] = CompletionCacheEntry(suggestion: suggestion, createdAt: Date())
        pruneCompletionCacheIfNeeded()
    }

    private func pruneCompletionCacheIfNeeded() {
        if completionCache.count <= 220 { return }
        let cutoff = Date().addingTimeInterval(-20)
        completionCache = completionCache.filter { $0.value.createdAt >= cutoff }
        if completionCache.count <= 200 { return }
        let sorted = completionCache.sorted { $0.value.createdAt > $1.value.createdAt }
        completionCache = Dictionary(uniqueKeysWithValues: sorted.prefix(200).map { ($0.key, $0.value) })
    }

    private func applyInlineSuggestion(_ suggestion: String, textView: NSTextView, selection: NSRange) {
        guard let accepting = textView as? AcceptingTextView else { return }
        let currentText = textView.string as NSString
        let currentSelection = textView.selectedRange()
        guard currentSelection.length == 0, currentSelection.location == selection.location else { return }
        let nextRangeLength = min(suggestion.count, currentText.length - selection.location)
        let nextText = nextRangeLength > 0 ? currentText.substring(with: NSRange(location: selection.location, length: nextRangeLength)) : ""
        if suggestion.isEmpty || nextText.starts(with: suggestion) {
            accepting.clearInlineSuggestion()
            return
        }
        accepting.showInlineSuggestion(suggestion, at: selection.location)
    }

    private func shouldThrottleHeavyEditorFeatures(in nsText: NSString? = nil) -> Bool {
        if effectiveLargeFileModeEnabled { return true }
        let length = nsText?.length ?? currentDocumentUTF16Length
        return length >= EditorPerformanceThresholds.heavyFeatureUTF16Length
    }

    private func shouldScheduleCompletion(for textView: NSTextView) -> Bool {
        let nsText = textView.string as NSString
        let selection = textView.selectedRange()
        guard selection.length == 0 else { return false }
        let location = selection.location
        guard location > 0, location <= nsText.length else { return false }
        if shouldThrottleHeavyEditorFeatures(in: nsText) { return false }

        let prevChar = nsText.substring(with: NSRange(location: location - 1, length: 1))
        let triggerChars: Set<String> = [".", "(", ")", "{", "}", "[", "]", ":", ",", "\n", "\t"]
        if triggerChars.contains(prevChar) { return true }
        if prevChar == " " {
            return CompletionHeuristics.shouldTriggerAfterWhitespace(
                in: nsText,
                caretLocation: location,
                language: currentLanguage
            )
        }

        let wordChars = CharacterSet.alphanumerics.union(CharacterSet(charactersIn: "_"))
        if prevChar.rangeOfCharacter(from: wordChars) == nil { return false }

        if location >= nsText.length { return true }
        let nextChar = nsText.substring(with: NSRange(location: location, length: 1))
        let separator = CharacterSet.whitespacesAndNewlines.union(.punctuationCharacters)
        return nextChar.rangeOfCharacter(from: separator) != nil
    }

    private func completionDebounceInterval(for textView: NSTextView) -> TimeInterval {
        let docLength = (textView.string as NSString).length
        if docLength >= 80_000 { return 0.9 }
        if docLength >= 25_000 { return 0.7 }
        return 0.45
    }

    private func completionTriggerSignature(for textView: NSTextView) -> String {
        let nsText = textView.string as NSString
        let selection = textView.selectedRange()
        guard selection.length == 0 else { return "" }
        let location = selection.location
        guard location > 0, location <= nsText.length else { return "" }

        let prevChar = nsText.substring(with: NSRange(location: location - 1, length: 1))
        let nextChar: String
        if location < nsText.length {
            nextChar = nsText.substring(with: NSRange(location: location, length: 1))
        } else {
            nextChar = ""
        }
        // Keep signature cheap while specific enough to skip duplicate notifications.
        return "\(location)|\(prevChar)|\(nextChar)|\(nsText.length)"
    }
    #endif

    private func externalModelCompletion(prefix: String, language: String) async -> String {
        // Try Grok
        if !grokAPIToken.isEmpty {
            do {
                guard let url = URL(string: "https://api.x.ai/v1/chat/completions") else { return "" }
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.setValue("Bearer \(grokAPIToken)", forHTTPHeaderField: "Authorization")
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
                let prompt = """
                Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.

                \(prefix)

                Completion:
                """
                let body: [String: Any] = [
                    "model": "grok-2-latest",
                    "messages": [["role": "user", "content": prompt]],
                    "temperature": 0.5,
                    "max_tokens": 64,
                    "n": 1,
                    "stop": [""]
                ]
                request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
                let (data, _) = try await URLSession.shared.data(for: request)
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let choices = json["choices"] as? [[String: Any]],
                   let message = choices.first?["message"] as? [String: Any],
                   let content = message["content"] as? String {
                    return sanitizeCompletion(content)
                }
            } catch {
                debugLog("[Completion][Fallback][Grok] request failed")
            }
        }
        // Try OpenAI
        if !openAIAPIToken.isEmpty {
            do {
                guard let url = URL(string: "https://api.openai.com/v1/chat/completions") else { return "" }
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.setValue("Bearer \(openAIAPIToken)", forHTTPHeaderField: "Authorization")
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
                let prompt = """
                Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.

                \(prefix)

                Completion:
                """
                let body: [String: Any] = [
                    "model": "gpt-4o-mini",
                    "messages": [["role": "user", "content": prompt]],
                    "temperature": 0.5,
                    "max_tokens": 64,
                    "n": 1,
                    "stop": [""]
                ]
                request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
                let (data, _) = try await URLSession.shared.data(for: request)
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let choices = json["choices"] as? [[String: Any]],
                   let message = choices.first?["message"] as? [String: Any],
                   let content = message["content"] as? String {
                    return sanitizeCompletion(content)
                }
            } catch {
                debugLog("[Completion][Fallback][OpenAI] request failed")
            }
        }
        // Try Gemini
        if !geminiAPIToken.isEmpty {
            do {
                let model = "gemini-1.5-flash-latest"
                let endpoint = "https://generativelanguage.googleapis.com/v1beta/models/\(model):generateContent"
                guard let url = URL(string: endpoint) else { return "" }
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.setValue(geminiAPIToken, forHTTPHeaderField: "x-goog-api-key")
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
                let prompt = """
                Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.

                \(prefix)

                Completion:
                """
                let body: [String: Any] = [
                    "contents": [["parts": [["text": prompt]]]],
                    "generationConfig": ["temperature": 0.5, "maxOutputTokens": 64]
                ]
                request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
                let (data, _) = try await URLSession.shared.data(for: request)
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let candidates = json["candidates"] as? [[String: Any]],
                   let first = candidates.first,
                   let content = first["content"] as? [String: Any],
                   let parts = content["parts"] as? [[String: Any]],
                   let text = parts.first?["text"] as? String {
                    return sanitizeCompletion(text)
                }
            } catch {
                debugLog("[Completion][Fallback][Gemini] request failed")
            }
        }
        // Try Anthropic
        if !anthropicAPIToken.isEmpty {
            do {
                guard let url = URL(string: "https://api.anthropic.com/v1/messages") else { return "" }
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.setValue(anthropicAPIToken, forHTTPHeaderField: "x-api-key")
                request.setValue("2023-06-01", forHTTPHeaderField: "anthropic-version")
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
                let prompt = """
                Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.

                \(prefix)

                Completion:
                """
                let body: [String: Any] = [
                    "model": "claude-3-5-haiku-latest",
                    "max_tokens": 64,
                    "temperature": 0.5,
                    "messages": [["role": "user", "content": prompt]]
                ]
                request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
                let (data, _) = try await URLSession.shared.data(for: request)
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let contentArr = json["content"] as? [[String: Any]],
                   let first = contentArr.first,
                   let text = first["text"] as? String {
                    return sanitizeCompletion(text)
                }
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let message = json["message"] as? [String: Any],
                   let contentArr = message["content"] as? [[String: Any]],
                   let first = contentArr.first,
                   let text = first["text"] as? String {
                    return sanitizeCompletion(text)
                }
            } catch {
                debugLog("[Completion][Fallback][Anthropic] request failed")
            }
        }
        return ""
    }

    private func appleModelCompletion(prefix: String, language: String) async -> String {
        let client = AppleIntelligenceAIClient()
        var aggregated = ""
        var firstChunk: String?
        for await chunk in client.streamSuggestions(prompt: "Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.\n\n\(prefix)\n\nCompletion:") {
            if firstChunk == nil, !chunk.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
                firstChunk = chunk
                break
            } else {
                aggregated += chunk
            }
        }
        let candidate = sanitizeCompletion((firstChunk ?? aggregated))
        await MainActor.run { lastProviderUsed = "Apple" }
        return candidate
    }

    private func generateModelCompletion(prefix: String, language: String) async -> String {
        switch selectedModel {
        case .appleIntelligence:
            return await appleModelCompletion(prefix: prefix, language: language)
        case .grok:
            if grokAPIToken.isEmpty {
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Grok (fallback to Apple)" }
                return res
            }
            do {
                guard let url = URL(string: "https://api.x.ai/v1/chat/completions") else {
                    let res = await appleModelCompletion(prefix: prefix, language: language)
                    await MainActor.run { lastProviderUsed = "Grok (fallback to Apple)" }
                    return res
                }
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.setValue("Bearer \(grokAPIToken)", forHTTPHeaderField: "Authorization")
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
                let prompt = """
                Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.

                \(prefix)

                Completion:
                """
                let body: [String: Any] = [
                    "model": "grok-2-latest",
                    "messages": [["role": "user", "content": prompt]],
                    "temperature": 0.5,
                    "max_tokens": 64,
                    "n": 1,
                    "stop": [""]
                ]
                request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
                let (data, _) = try await URLSession.shared.data(for: request)
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let choices = json["choices"] as? [[String: Any]],
                   let message = choices.first?["message"] as? [String: Any],
                   let content = message["content"] as? String {
                    await MainActor.run { lastProviderUsed = "Grok" }
                    return sanitizeCompletion(content)
                }
                // If no content, fallback to Apple
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Grok (fallback to Apple)" }
                return res
            } catch {
                debugLog("[Completion][Grok] request failed")
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Grok (fallback to Apple)" }
                return res
            }
        case .openAI:
            if openAIAPIToken.isEmpty {
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "OpenAI (fallback to Apple)" }
                return res
            }
            do {
                guard let url = URL(string: "https://api.openai.com/v1/chat/completions") else {
                    let res = await appleModelCompletion(prefix: prefix, language: language)
                    await MainActor.run { lastProviderUsed = "OpenAI (fallback to Apple)" }
                    return res
                }
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.setValue("Bearer \(openAIAPIToken)", forHTTPHeaderField: "Authorization")
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
                let prompt = """
                Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.

                \(prefix)

                Completion:
                """
                let body: [String: Any] = [
                    "model": "gpt-4o-mini",
                    "messages": [["role": "user", "content": prompt]],
                    "temperature": 0.5,
                    "max_tokens": 64,
                    "n": 1,
                    "stop": [""]
                ]
                request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
                let (data, _) = try await URLSession.shared.data(for: request)
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let choices = json["choices"] as? [[String: Any]],
                   let message = choices.first?["message"] as? [String: Any],
                   let content = message["content"] as? String {
                    await MainActor.run { lastProviderUsed = "OpenAI" }
                    return sanitizeCompletion(content)
                }
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "OpenAI (fallback to Apple)" }
                return res
            } catch {
                debugLog("[Completion][OpenAI] request failed")
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "OpenAI (fallback to Apple)" }
                return res
            }
        case .gemini:
            if geminiAPIToken.isEmpty {
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Gemini (fallback to Apple)" }
                return res
            }
            do {
                let model = "gemini-1.5-flash-latest"
                let endpoint = "https://generativelanguage.googleapis.com/v1beta/models/\(model):generateContent"
                guard let url = URL(string: endpoint) else {
                    let res = await appleModelCompletion(prefix: prefix, language: language)
                    await MainActor.run { lastProviderUsed = "Gemini (fallback to Apple)" }
                    return res
                }
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.setValue(geminiAPIToken, forHTTPHeaderField: "x-goog-api-key")
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
                let prompt = """
                Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.

                \(prefix)

                Completion:
                """
                let body: [String: Any] = [
                    "contents": [["parts": [["text": prompt]]]],
                    "generationConfig": ["temperature": 0.5, "maxOutputTokens": 64]
                ]
                request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
                let (data, _) = try await URLSession.shared.data(for: request)
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let candidates = json["candidates"] as? [[String: Any]],
                   let first = candidates.first,
                   let content = first["content"] as? [String: Any],
                   let parts = content["parts"] as? [[String: Any]],
                   let text = parts.first?["text"] as? String {
                    await MainActor.run { lastProviderUsed = "Gemini" }
                    return sanitizeCompletion(text)
                }
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Gemini (fallback to Apple)" }
                return res
            } catch {
                debugLog("[Completion][Gemini] request failed")
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Gemini (fallback to Apple)" }
                return res
            }
        case .anthropic:
            if anthropicAPIToken.isEmpty {
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Anthropic (fallback to Apple)" }
                return res
            }
            do {
                guard let url = URL(string: "https://api.anthropic.com/v1/messages") else {
                    let res = await appleModelCompletion(prefix: prefix, language: language)
                    await MainActor.run { lastProviderUsed = "Anthropic (fallback to Apple)" }
                    return res
                }
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.setValue(anthropicAPIToken, forHTTPHeaderField: "x-api-key")
                request.setValue("2023-06-01", forHTTPHeaderField: "anthropic-version")
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
                let prompt = """
                Continue the following \(language) code snippet with a few lines or tokens of code only. Do not add prose or explanations.

                \(prefix)

                Completion:
                """
                let body: [String: Any] = [
                    "model": "claude-3-5-haiku-latest",
                    "max_tokens": 64,
                    "temperature": 0.5,
                    "messages": [["role": "user", "content": prompt]]
                ]
                request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
                let (data, _) = try await URLSession.shared.data(for: request)
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let contentArr = json["content"] as? [[String: Any]],
                   let first = contentArr.first,
                   let text = first["text"] as? String {
                    await MainActor.run { lastProviderUsed = "Anthropic" }
                    return sanitizeCompletion(text)
                }
                if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
                   let message = json["message"] as? [String: Any],
                   let contentArr = message["content"] as? [[String: Any]],
                   let first = contentArr.first,
                   let text = first["text"] as? String {
                    await MainActor.run { lastProviderUsed = "Anthropic" }
                    return sanitizeCompletion(text)
                }
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Anthropic (fallback to Apple)" }
                return res
            } catch {
                debugLog("[Completion][Anthropic] request failed")
                let res = await appleModelCompletion(prefix: prefix, language: language)
                await MainActor.run { lastProviderUsed = "Anthropic (fallback to Apple)" }
                return res
            }
        }
    }

    private func sanitizeCompletion(_ raw: String) -> String {
        CompletionHeuristics.sanitizeModelSuggestion(raw, currentTokenPrefix: "", nextDocumentText: "")
    }

    private func debugLog(_ message: String) {
        if message.contains("[Completion]") || message.contains("AI ") || message.contains("[AI]") {
            AIActivityLog.record(message, source: "Completion")
        }
#if DEBUG
        print(message)
#endif
    }

#if os(macOS)
    private func matchesCurrentWindow(_ notif: Notification) -> Bool {
        guard let target = notif.userInfo?[EditorCommandUserInfo.windowNumber] as? Int else {
            return true
        }
        guard let hostWindowNumber else { return false }
        return target == hostWindowNumber
    }

    private func updateWindowRegistration(_ window: NSWindow?) {
        let number = window?.windowNumber
        if hostWindowNumber != number, let old = hostWindowNumber {
            WindowViewModelRegistry.shared.unregister(windowNumber: old)
        }
        hostWindowNumber = number
        installWindowCloseConfirmationDelegate(window)
        updateWindowChrome(window)
        if let number {
            WindowViewModelRegistry.shared.register(viewModel, for: number)
        }
    }

    private func updateWindowChrome(_ window: NSWindow? = nil) {
        guard let targetWindow = window ?? hostWindowNumber.flatMap({ NSApp.window(withWindowNumber: $0) }) else { return }
        targetWindow.subtitle = windowSubtitleText
    }

    private func saveAllDirtyTabsForWindowClose() -> Bool {
        let dirtyTabIDs = viewModel.tabs.filter(\.isDirty).map(\.id)
        guard !dirtyTabIDs.isEmpty else { return true }
        for tabID in dirtyTabIDs {
            guard viewModel.tabs.contains(where: { $0.id == tabID }) else { continue }
            viewModel.saveFile(tabID: tabID)
            guard let updated = viewModel.tabs.first(where: { $0.id == tabID }), !updated.isDirty else {
                return false
            }
        }
        return true
    }

    private func windowCloseDialogMessage() -> String {
        let dirtyCount = viewModel.tabs.filter(\.isDirty).count
        if dirtyCount <= 1 {
            return "You have unsaved changes in one tab."
        }
        return "You have unsaved changes in \(dirtyCount) tabs."
    }

    private func installWindowCloseConfirmationDelegate(_ window: NSWindow?) {
        guard let window else {
            windowCloseConfirmationDelegate = nil
            return
        }

        let delegate: WindowCloseConfirmationDelegate
        if let existing = windowCloseConfirmationDelegate {
            delegate = existing
        } else {
            delegate = WindowCloseConfirmationDelegate()
            windowCloseConfirmationDelegate = delegate
        }

        if window.delegate !== delegate {
            if let current = window.delegate, current !== delegate {
                delegate.forwardedDelegate = current
            }
            window.delegate = delegate
        }

        delegate.shouldConfirm = { confirmCloseDirtyTab }
        delegate.hasDirtyTabs = { viewModel.tabs.contains(where: \.isDirty) }
        delegate.saveAllDirtyTabs = { saveAllDirtyTabsForWindowClose() }
        delegate.dialogTitle = { "Save changes before closing?" }
        delegate.dialogMessage = { windowCloseDialogMessage() }
    }

    private func requestBracketHelperInsert(_ token: String) {
        let targetWindow = hostWindowNumber ?? NSApp.keyWindow?.windowNumber ?? NSApp.mainWindow?.windowNumber
        var userInfo: [String: Any] = [EditorCommandUserInfo.bracketToken: token]
        if let targetWindow {
            userInfo[EditorCommandUserInfo.windowNumber] = targetWindow
        }
        NotificationCenter.default.post(
            name: .insertBracketHelperTokenRequested,
            object: nil,
            userInfo: userInfo
        )
    }
#else
    private func matchesCurrentWindow(_ notif: Notification) -> Bool { true }
#endif

#if os(macOS)
    private var bracketHelperBar: some View {
        ScrollView(.horizontal, showsIndicators: false) {
            HStack(spacing: 8) {
                ForEach(bracketHelperTokens, id: \.self) { token in
                    Button(action: {
                        requestBracketHelperInsert(token)
                    }) {
                        Text(token)
                            .font(.system(size: 13, weight: .semibold, design: .monospaced))
                            .padding(.horizontal, 10)
                            .padding(.vertical, 5)
                            .contentShape(Rectangle())
                            .background(
                                RoundedRectangle(cornerRadius: 8, style: .continuous)
                                    .fill(Color.accentColor.opacity(0.14))
                            )
                    }
                    .buttonStyle(.plain)
                    .accessibilityLabel(Text("Insert \(token)"))
                }
            }
            .padding(.horizontal, 10)
            .padding(.vertical, 6)
        }
        .background(editorSurfaceBackgroundStyle)
    }
#endif

    private func withBaseEditorEvents<Content: View>(_ view: Content) -> some View {
        let viewWithClipboardEvents = view
            .onReceive(NotificationCenter.default.publisher(for: .caretPositionDidChange)) { notif in
                if let location = notif.userInfo?["location"] as? Int, location >= 0 {
                    lastCaretLocation = location
                    if let selectedURL = viewModel.selectedTab?.fileURL?.standardizedFileURL {
                        sessionCaretByFileURL[selectedURL.absoluteString] = location
                    }
                }
                if let line = notif.userInfo?["line"] as? Int, let col = notif.userInfo?["column"] as? Int {
                    if line <= 0 {
                        caretStatus = "Pos \(col)"
                    } else {
                        caretStatus = "Ln \(line), Col \(col)"
                    }
                }
#if os(iOS)
                // Keep floating status pill word count in sync with live buffer while typing.
                let liveText = liveEditorBufferText() ?? currentContent
                scheduleWordCountRefresh(for: liveText)
#endif
            }
            .onReceive(NotificationCenter.default.publisher(for: .editorSelectionDidChange)) { notif in
                let selection = (notif.object as? String) ?? ""
                currentSelectionSnapshotText = selection
            }
            .onReceive(NotificationCenter.default.publisher(for: .editorRequestCodeSnapshotFromSelection)) { _ in
                presentCodeSnapshotComposer()
            }
            .onReceive(NotificationCenter.default.publisher(for: .pastedText)) { notif in
                handlePastedTextNotification(notif)
            }
            .onReceive(NotificationCenter.default.publisher(for: .pastedFileURL)) { notif in
                handlePastedFileNotification(notif)
            }
            .onReceive(NotificationCenter.default.publisher(for: .zoomEditorFontRequested)) { notif in
                let delta: Double = {
                    if let d = notif.object as? Double { return d }
                    if let n = notif.object as? NSNumber { return n.doubleValue }
                    return 1
                }()
                adjustEditorFontSize(delta)
            }
            .onReceive(NotificationCenter.default.publisher(for: .droppedFileURL)) { notif in
                handleDroppedFileNotification(notif)
            }

        let viewWithDroppedFileLoadEvents = AnyView(
            viewWithClipboardEvents
            .onReceive(NotificationCenter.default.publisher(for: .droppedFileLoadStarted)) { notif in
                droppedFileLoadInProgress = true
                droppedFileProgressDeterminate = (notif.userInfo?["isDeterminate"] as? Bool) ?? true
                droppedFileLoadProgress = 0
                droppedFileLoadLabel = "Reading file"
                largeFileModeEnabled = (notif.userInfo?["largeFileMode"] as? Bool) ?? false
            }
            .onReceive(NotificationCenter.default.publisher(for: .droppedFileLoadProgress)) { notif in
                // Recover even if "started" was missed.
                droppedFileLoadInProgress = true
                if let determinate = notif.userInfo?["isDeterminate"] as? Bool {
                    droppedFileProgressDeterminate = determinate
                }
                let fraction: Double = {
                    if let v = notif.userInfo?["fraction"] as? Double { return v }
                    if let v = notif.userInfo?["fraction"] as? NSNumber { return v.doubleValue }
                    if let v = notif.userInfo?["fraction"] as? Float { return Double(v) }
                    if let v = notif.userInfo?["fraction"] as? CGFloat { return Double(v) }
                    return droppedFileLoadProgress
                }()
                droppedFileLoadProgress = min(max(fraction, 0), 1)
                if (notif.userInfo?["largeFileMode"] as? Bool) == true {
                    largeFileModeEnabled = true
                }
                if let name = notif.userInfo?["fileName"] as? String, !name.isEmpty {
                    droppedFileLoadLabel = name
                }
            }
            .onReceive(NotificationCenter.default.publisher(for: .droppedFileLoadFinished)) { notif in
                let success = (notif.userInfo?["success"] as? Bool) ?? true
                droppedFileLoadProgress = success ? 1 : 0
                droppedFileProgressDeterminate = true
                if (notif.userInfo?["largeFileMode"] as? Bool) == true {
                    largeFileModeEnabled = true
                }
                if !success, let message = notif.userInfo?["message"] as? String, !message.isEmpty {
                    findStatusMessage = "Drop failed: \(message)"
                    droppedFileLoadLabel = "Import failed"
                }
                DispatchQueue.main.asyncAfter(deadline: .now() + (success ? 0.35 : 2.5)) {
                    droppedFileLoadInProgress = false
                }
            }
        )

        let viewWithSelectionObservers = AnyView(
            viewWithDroppedFileLoadEvents
            .onChange(of: viewModel.selectedTab?.id) { _, _ in
                editorExternalMutationRevision &+= 1
                updateLargeFileModeForCurrentContext()
                scheduleLargeFileModeReevaluation(after: 0.9)
                scheduleHighlightRefresh()
                if let selectedID = viewModel.selectedTab?.id {
                    viewModel.refreshExternalConflictForTab(tabID: selectedID)
                }
                restoreCaretForSelectedSessionFileIfAvailable()
                persistSessionIfReady()
            }
            .onChange(of: viewModel.selectedTab?.isLoadingContent ?? false) { _, isLoading in
                if isLoading {
                    let shouldPreEnableLargeMode =
                        droppedFileLoadInProgress ||
                        viewModel.selectedTab?.isLargeFileCandidate == true ||
                        currentDocumentUTF16Length >= 300_000
                    if shouldPreEnableLargeMode, !largeFileModeEnabled {
                        largeFileModeEnabled = true
                    }
                } else {
                    scheduleLargeFileModeReevaluation(after: 0.8)
                }
                scheduleHighlightRefresh()
            }
            .onChange(of: currentLanguage) { _, newValue in
                settingsTemplateLanguage = newValue
            }
            .onChange(of: viewModel.pendingExternalFileConflict?.tabID) { _, conflictTabID in
                if conflictTabID != nil {
                    showExternalConflictDialog = true
                }
            }
            .onChange(of: viewModel.pendingRemoteSaveIssue?.tabID) { _, issueTabID in
                if issueTabID != nil {
                    showRemoteSaveIssueDialog = true
                }
            }
        )

        return viewWithSelectionObservers
            .onChange(of: showRemoteSaveIssueDialog) { _, isPresented in
                if !isPresented, viewModel.pendingRemoteSaveIssue != nil {
                    viewModel.dismissRemoteSaveIssue()
                }
            }
    }

    private func handlePastedTextNotification(_ notif: Notification) {
        guard let pasted = notif.object as? String else {
            DispatchQueue.main.async {
                updateLargeFileModeForCurrentContext()
                scheduleHighlightRefresh()
            }
            return
        }
        let result = LanguageDetector.shared.detect(text: pasted, name: nil, fileURL: nil)
        if let tab = viewModel.selectedTab,
           !tab.languageLocked,
           tab.language == "plain",
           result.lang != "plain" {
            viewModel.setTabLanguage(tabID: tab.id, language: result.lang, lock: false)
        } else if singleLanguage == "plain", result.lang != "plain" {
            singleLanguage = result.lang
        }
        DispatchQueue.main.async {
            updateLargeFileModeForCurrentContext()
            scheduleHighlightRefresh()
        }
    }

    private func handlePastedFileNotification(_ notif: Notification) {
        var urls: [URL] = []
        if let url = notif.object as? URL {
            urls = [url]
        } else if let list = notif.object as? [URL] {
            urls = list
        }
        guard !urls.isEmpty else { return }
        for url in urls {
            viewModel.openFile(url: url)
        }
        DispatchQueue.main.async {
            updateLargeFileModeForCurrentContext()
            scheduleHighlightRefresh()
        }
    }

    private func handleDroppedFileNotification(_ notif: Notification) {
        guard let fileURL = notif.object as? URL else { return }
        if let preferred = LanguageDetector.shared.preferredLanguage(for: fileURL) {
            if let tab = viewModel.selectedTab,
               !tab.languageLocked,
               tab.language == "plain" {
                viewModel.setTabLanguage(tabID: tab.id, language: preferred, lock: false)
            } else if singleLanguage == "plain" {
                singleLanguage = preferred
            }
        }
        DispatchQueue.main.async {
            updateLargeFileModeForCurrentContext()
            scheduleHighlightRefresh()
        }
    }

    func updateLargeFileMode(for text: String) {
        if droppedFileLoadInProgress {
            if !largeFileModeEnabled {
                largeFileModeEnabled = true
                scheduleHighlightRefresh()
            }
            return
        }
        if viewModel.selectedTab?.isLoadingContent == true {
            if (viewModel.selectedTab?.isLargeFileCandidate == true || currentDocumentUTF16Length >= 300_000),
               !largeFileModeEnabled {
                largeFileModeEnabled = true
                scheduleHighlightRefresh()
            }
            return
        }
        if viewModel.selectedTab?.isLargeFileCandidate == true {
            if !largeFileModeEnabled {
                largeFileModeEnabled = true
                scheduleHighlightRefresh()
            }
            return
        }
        let lowerLanguage = currentLanguage.lowercased()
        let isHTMLLike = ["html", "htm", "xml", "svg", "xhtml"].contains(lowerLanguage)
        let isCSVLike = ["csv", "tsv"].contains(lowerLanguage)
        let useAggressiveThresholds = isHTMLLike || isCSVLike
        #if os(iOS)
        var byteThreshold = useAggressiveThresholds
            ? EditorPerformanceThresholds.largeFileBytesHTMLCSVMobile
            : EditorPerformanceThresholds.largeFileBytesMobile
        var lineThreshold = useAggressiveThresholds
            ? EditorPerformanceThresholds.largeFileLineBreaksHTMLCSVMobile
            : EditorPerformanceThresholds.largeFileLineBreaksMobile
        #else
        var byteThreshold = useAggressiveThresholds
            ? EditorPerformanceThresholds.largeFileBytesHTMLCSV
            : EditorPerformanceThresholds.largeFileBytes
        var lineThreshold = useAggressiveThresholds
            ? EditorPerformanceThresholds.largeFileLineBreaksHTMLCSV
            : EditorPerformanceThresholds.largeFileLineBreaks
        #endif
        switch performancePreset {
        case .balanced:
            break
        case .largeFiles:
            byteThreshold = max(1_000_000, Int(Double(byteThreshold) * 0.75))
            lineThreshold = max(5_000, Int(Double(lineThreshold) * 0.75))
        case .battery:
            byteThreshold = max(750_000, Int(Double(byteThreshold) * 0.55))
            lineThreshold = max(3_000, Int(Double(lineThreshold) * 0.55))
        }
        let byteCount = text.utf8.count
        let exceedsByteThreshold = byteCount >= byteThreshold
        let exceedsLineThreshold: Bool = {
            if exceedsByteThreshold { return true }
            var lineBreaks = 0
            var currentLineLength = 0
            let csvLongLineThreshold = 16_000
            for codeUnit in text.utf16 {
                if codeUnit == 10 { // '\n'
                    lineBreaks += 1
                    currentLineLength = 0
                    if lineBreaks >= lineThreshold {
                        return true
                    }
                    continue
                }
                if isCSVLike {
                    currentLineLength += 1
                    if currentLineLength >= csvLongLineThreshold {
                        return true
                    }
                }
            }
            return false
        }()
#if os(iOS)
        let isLarge = forceLargeFileMode
            || exceedsByteThreshold
            || exceedsLineThreshold
#else
        let isLarge = exceedsByteThreshold
            || exceedsLineThreshold
#endif
        if largeFileModeEnabled != isLarge {
            largeFileModeEnabled = isLarge
            scheduleHighlightRefresh()
        }
    }

    private func updateLargeFileModeForCurrentContext() {
        if droppedFileLoadInProgress {
            if !largeFileModeEnabled {
                largeFileModeEnabled = true
                scheduleHighlightRefresh()
            }
            return
        }
        if viewModel.selectedTab?.isLoadingContent == true {
            if (viewModel.selectedTab?.isLargeFileCandidate == true || currentDocumentUTF16Length >= 300_000),
               !largeFileModeEnabled {
                largeFileModeEnabled = true
                scheduleHighlightRefresh()
            }
            return
        }
        if viewModel.selectedTab?.isLargeFileCandidate == true || currentDocumentUTF16Length >= 300_000 {
            if !largeFileModeEnabled {
                largeFileModeEnabled = true
                scheduleHighlightRefresh()
            }
            return
        }
        guard let snapshot = currentContentSnapshot(maxUTF16Length: 280_000) else { return }
        updateLargeFileMode(for: snapshot)
    }

    private func currentContentSnapshot(maxUTF16Length: Int) -> String? {
        guard currentDocumentUTF16Length <= maxUTF16Length else { return nil }
        return liveEditorBufferText() ?? currentContentBinding.wrappedValue
    }

    private func refreshSecondaryContentViewsIfNeeded() {
        guard let snapshot = currentContentSnapshot(maxUTF16Length: 280_000) else {
            scheduleWordCountRefreshForLargeContent()
            if shouldShowDelimitedTable {
                delimitedParseTask?.cancel()
                isBuildingDelimitedTable = false
                delimitedTableSnapshot = nil
            }
            return
        }
        scheduleWordCountRefresh(for: snapshot)
        if shouldShowDelimitedTable {
            scheduleDelimitedTableRebuild(for: snapshot)
        }
    }

    private func scheduleWordCountRefreshForLargeContent() {
        wordCountTask?.cancel()
        if statusWordCount != 0 {
            statusWordCount = 0
        }
        if let liveText = liveEditorBufferText() {
            let snapshot = liveText
            wordCountTask = Task(priority: .utility) {
                let lineCount = Self.lineCount(for: snapshot)
                await MainActor.run {
                    statusLineCount = lineCount
                }
            }
        }
    }

    private nonisolated static func lineCount(for text: String) -> Int {
        guard !text.isEmpty else { return 1 }
        var lineCount = 1
        for codeUnit in text.utf16 where codeUnit == 10 {
            lineCount += 1
        }
        return lineCount
    }

    private func scheduleLargeFileModeReevaluation(after delay: TimeInterval) {
        pendingLargeFileModeReevaluation?.cancel()
        let work = DispatchWorkItem {
            updateLargeFileModeForCurrentContext()
        }
        pendingLargeFileModeReevaluation = work
        DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: work)
    }

    func recordDiagnostic(_ message: String) {
#if DEBUG
        print("[NVE] \(message)")
#endif
    }

    func adjustEditorFontSize(_ delta: Double) {
        let clamped = min(28, max(10, editorFontSize + delta))
        if clamped != editorFontSize {
            editorFontSize = clamped
            scheduleHighlightRefresh()
        }
    }

    private func pastedFileURL(from text: String) -> URL? {
        let trimmed = text.trimmingCharacters(in: .whitespacesAndNewlines)
        if trimmed.hasPrefix("file://"), let url = URL(string: trimmed), FileManager.default.fileExists(atPath: url.path) {
            return url
        }
        if trimmed.hasPrefix("/") && FileManager.default.fileExists(atPath: trimmed) {
            return URL(fileURLWithPath: trimmed)
        }
        return nil
    }

    private func withCommandEvents<Content: View>(_ view: Content) -> some View {
        let viewWithEditorActions = view
            .onReceive(NotificationCenter.default.publisher(for: .clearEditorRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                requestClearEditorContent()
            }
            .onChange(of: isAutoCompletionEnabled) { _, enabled in
                if enabled && viewModel.isBrainDumpMode {
                    viewModel.isBrainDumpMode = false
                    UserDefaults.standard.set(false, forKey: "BrainDumpModeEnabled")
                }
                syncAppleCompletionAvailability()
                if enabled && currentLanguage == "plain" && !showLanguageSetupPrompt {
                    showLanguageSetupPrompt = true
                }
            }
            .onReceive(NotificationCenter.default.publisher(for: .toggleVimModeRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                vimModeEnabled.toggle()
                UserDefaults.standard.set(vimModeEnabled, forKey: "EditorVimModeEnabled")
                UserDefaults.standard.set(vimModeEnabled, forKey: "EditorVimInterceptionEnabled")
                vimInsertMode = !vimModeEnabled
                NotificationCenter.default.post(
                    name: .vimModeStateDidChange,
                    object: nil,
                    userInfo: ["insertMode": vimInsertMode]
                )
            }
            .onReceive(NotificationCenter.default.publisher(for: .toggleSidebarRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                toggleSidebarFromToolbar()
            }
            .onReceive(NotificationCenter.default.publisher(for: .toggleBrainDumpModeRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
#if os(iOS)
                viewModel.isBrainDumpMode = false
                UserDefaults.standard.set(false, forKey: "BrainDumpModeEnabled")
#else
                viewModel.isBrainDumpMode.toggle()
                UserDefaults.standard.set(viewModel.isBrainDumpMode, forKey: "BrainDumpModeEnabled")
#endif
            }
            .onReceive(NotificationCenter.default.publisher(for: .toggleTranslucencyRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                if let enabled = notif.object as? Bool {
                    enableTranslucentWindow = enabled
                    UserDefaults.standard.set(enabled, forKey: "EnableTranslucentWindow")
                }
            }
            .onReceive(NotificationCenter.default.publisher(for: .vimModeStateDidChange)) { notif in
                if let isInsert = notif.userInfo?["insertMode"] as? Bool {
                    vimInsertMode = isInsert
                }
            }

        let viewWithPanelTriggers = viewWithEditorActions
            .onReceive(NotificationCenter.default.publisher(for: .showFindReplaceRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                showFindReplace = true
            }
            .onReceive(NotificationCenter.default.publisher(for: .findNextRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                findNext()
            }
            .onReceive(NotificationCenter.default.publisher(for: .showQuickSwitcherRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                quickSwitcherQuery = ""
                showQuickSwitcher = true
            }
            .onReceive(NotificationCenter.default.publisher(for: .openRecentFileRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                guard let url = notif.object as? URL else { return }
                _ = viewModel.openFile(url: url)
            }
            .onReceive(NotificationCenter.default.publisher(for: .recentFilesDidChange)) { _ in
                recentFilesRefreshToken = UUID()
            }
            .onReceive(NotificationCenter.default.publisher(for: .addNextMatchRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                addNextMatchSelection()
            }
            .onReceive(NotificationCenter.default.publisher(for: .showFindInFilesRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                if findInFilesQuery.isEmpty {
                    findInFilesQuery = findQuery
                }
                showFindInFiles = true
            }
            .onReceive(NotificationCenter.default.publisher(for: .showWelcomeTourRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                showWelcomeTour = true
            }
            .onReceive(NotificationCenter.default.publisher(for: .showEditorHelpRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                showEditorHelp = true
            }
            .onReceive(NotificationCenter.default.publisher(for: .showSupportPromptRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                showSupportPromptSheet = true
            }

        let viewWithPanels = viewWithPanelTriggers
            .onReceive(NotificationCenter.default.publisher(for: .toggleProjectStructureSidebarRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                toggleProjectSidebarFromToolbar()
            }
            .onReceive(NotificationCenter.default.publisher(for: .openProjectFolderRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                openProjectFolder()
            }
            .onReceive(NotificationCenter.default.publisher(for: .showAPISettingsRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                openAPISettings()
            }
            .onReceive(NotificationCenter.default.publisher(for: .showSettingsRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                if let tab = notif.object as? String, !tab.isEmpty {
                    openSettings(tab: tab)
                } else {
                    openSettings()
                }
            }
            .onReceive(NotificationCenter.default.publisher(for: .closeSelectedTabRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                guard let tab = viewModel.selectedTab else { return }
                requestCloseTab(tab)
            }
            .onReceive(NotificationCenter.default.publisher(for: .showUpdaterRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                let shouldCheckNow = (notif.object as? Bool) ?? true
                showUpdaterDialog(checkNow: shouldCheckNow)
            }
            .onReceive(NotificationCenter.default.publisher(for: .selectAIModelRequested)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                guard let modelRawValue = notif.object as? String,
                      let model = AIModel(rawValue: modelRawValue) else { return }
                selectedModelRaw = model.rawValue
            }

        return viewWithPanels
    }

    private func withTypingEvents<Content: View>(_ view: Content) -> some View {
#if os(macOS)
        view
            .onReceive(NotificationCenter.default.publisher(for: NSText.didChangeNotification)) { notif in
                guard isAutoCompletionEnabled && !viewModel.isBrainDumpMode && !isApplyingCompletion else { return }
                guard let changedTextView = notif.object as? NSTextView else { return }
                guard let activeTextView = NSApp.keyWindow?.firstResponder as? NSTextView, changedTextView === activeTextView else { return }
                if let hostWindowNumber,
                   let changedWindowNumber = changedTextView.window?.windowNumber,
                   changedWindowNumber != hostWindowNumber {
                    return
                }
                guard shouldScheduleCompletion(for: changedTextView) else { return }
                let signature = completionTriggerSignature(for: changedTextView)
                guard !signature.isEmpty else { return }
                if signature == lastCompletionTriggerSignature {
                    return
                }
                lastCompletionTriggerSignature = signature
                completionDebounceTask?.cancel()
                completionTask?.cancel()
                let debounce = completionDebounceInterval(for: changedTextView)
                completionDebounceTask = Task { @MainActor [weak changedTextView] in
                    let delay = UInt64((debounce * 1_000_000_000).rounded())
                    try? await Task.sleep(nanoseconds: delay)
                    guard !Task.isCancelled, let changedTextView else { return }
                    lastCompletionTriggerSignature = ""
                    performInlineCompletion(for: changedTextView)
                }
            }
#else
        view
#endif
    }

    @ViewBuilder
    private var platformLayout: some View {
#if os(macOS)
        Group {
            if shouldUseSplitView {
                NavigationSplitView {
                    sidebarView
                } detail: {
                    editorView
                }
                .navigationSplitViewColumnWidth(min: 200, ideal: 250, max: 600)
                .background(editorSurfaceBackgroundStyle)
            } else {
                editorView
            }
        }
        .frame(minWidth: 600, minHeight: 400)
#else
        NavigationStack {
            Group {
                if shouldUseSplitView {
                    NavigationSplitView {
                        sidebarView
                    } detail: {
                        editorView
                    }
                .navigationSplitViewColumnWidth(min: 200, ideal: 250, max: 600)
                .background(editorSurfaceBackgroundStyle)
                } else {
                    editorView
                }
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
#endif
    }

    // Layout: NavigationSplitView with optional sidebar and the primary code editor.
    var body: some View {
        lifecycleConfiguredRootView
#if os(macOS)
        .background(
            WindowAccessor { window in
                updateWindowRegistration(window)
            }
            .frame(width: 0, height: 0)
        )
        .background(
            FindReplaceWindowPresenter(
                isPresented: $showFindReplace,
                findQuery: $findQuery,
                replaceQuery: $replaceQuery,
                useRegex: $findUsesRegex,
                caseSensitive: $findCaseSensitive,
                matchCount: $findMatchCount,
                statusMessage: $findStatusMessage,
                onPreviewChanged: { refreshFindPreview() },
                onFindNext: {
                    findNext()
                    refreshFindMatchCount()
                },
                onJumpToMatch: { jumpToCurrentFindMatch() },
                onReplace: {
                    replaceSelection()
                    refreshFindPreview()
                },
                onReplaceAll: {
                    replaceAll()
                    refreshFindPreview()
                },
                onClose: { showFindReplace = false }
            )
            .frame(width: 0, height: 0)
        )
        .onDisappear {
            handleWindowDisappear()
        }
        .onChange(of: viewModel.tabsObservationToken) { _, _ in
            updateWindowChrome()
        }
        .onChange(of: largeFileOpenModeRaw) { _, _ in
            updateWindowChrome()
        }
        .onChange(of: remoteSessionsEnabled) { _, _ in
            updateWindowChrome()
        }
        .onChange(of: remotePreparedTarget) { _, _ in
            updateWindowChrome()
        }
#endif
    }

    private var basePlatformRootView: some View {
        AnyView(platformLayout)
            .alert("AI Error", isPresented: showGrokError) {
                Button("OK") { }
            } message: {
                Text(grokErrorMessage.wrappedValue)
            }
            .alert(
                "Whitespace Scalars",
                isPresented: Binding(
                    get: { whitespaceInspectorMessage != nil },
                    set: { if !$0 { whitespaceInspectorMessage = nil } }
                )
            ) {
                Button("OK", role: .cancel) { }
            } message: {
                Text(whitespaceInspectorMessage ?? "")
            }
            .alert(
                "PDF Export Failed",
                isPresented: Binding(
                    get: { markdownPDFExportErrorMessage != nil },
                    set: { if !$0 { markdownPDFExportErrorMessage = nil } }
                )
            ) {
                Button("OK", role: .cancel) { }
            } message: {
                Text(markdownPDFExportErrorMessage ?? "")
            }
            .navigationTitle("Neon Vision Editor")
#if os(iOS)
            .navigationBarTitleDisplayMode(.inline)
            .background(
                IPadKeyboardShortcutBridge(
                    onNewTab: { viewModel.addNewTab() },
                    onOpenFile: { openFileFromToolbar() },
                    onSave: { saveCurrentTabFromToolbar() },
                    onFind: { showFindReplace = true },
                    onFindInFiles: { showFindInFiles = true },
                    onQuickOpen: {
                        quickSwitcherQuery = ""
                        showQuickSwitcher = true
                    },
                    onToggleSidebar: { toggleSidebarFromToolbar() },
                    onToggleProjectSidebar: { toggleProjectSidebarFromToolbar() }
                )
                .frame(width: 0, height: 0)
            )
#endif
    }

    private var rootViewWithStateObservers: some View {
        applyUpdateVisibilityObservers(to: basePlatformRootView)
            .onAppear {
                handleSettingsAndEditorDefaultsOnAppear()
            }
            .onChange(of: settingsLineWrapEnabled) { _, enabled in
                let target = projectOverrideLineWrapEnabled ?? enabled
                if viewModel.isLineWrapEnabled != target {
                    viewModel.isLineWrapEnabled = target
                }
            }
            .onChange(of: viewModel.isLineWrapEnabled) { _, enabled in
                guard projectOverrideLineWrapEnabled == nil else { return }
                if settingsLineWrapEnabled != enabled {
                    settingsLineWrapEnabled = enabled
                }
            }
            .onChange(of: settingsThemeName) { _, _ in
                scheduleHighlightRefresh()
            }
            .onChange(of: themeFormattingRefreshSignature) { _, _ in
                scheduleHighlightRefresh()
            }
            .onChange(of: highlightMatchingBrackets) { _, _ in
                scheduleHighlightRefresh()
            }
            .onChange(of: showScopeGuides) { _, _ in
                scheduleHighlightRefresh()
            }
            .onChange(of: highlightScopeBackground) { _, _ in
                scheduleHighlightRefresh()
            }
            .onChange(of: viewModel.isLineWrapEnabled) { _, _ in
                scheduleHighlightRefresh()
            }
            .onChange(of: viewModel.tabsObservationToken) { _, _ in
                persistSessionIfReady()
                persistUnsavedDraftSnapshotIfNeeded()
            }
            .onChange(of: viewModel.showSidebar) { _, _ in
                persistSessionIfReady()
            }
            .onChange(of: showProjectStructureSidebar) { _, _ in
                persistSessionIfReady()
            }
            .onChange(of: showSupportedProjectFilesOnly) { _, _ in
                refreshProjectBrowserState()
            }
            .onChange(of: showMarkdownPreviewPane) { _, _ in
                persistSessionIfReady()
            }
	    }

    private func applyUpdateVisibilityObservers<Content: View>(to view: Content) -> some View {
        view
            .onReceive(NotificationCenter.default.publisher(for: .whitespaceScalarInspectionResult)) { notif in
                guard matchesCurrentWindow(notif) else { return }
                if let msg = notif.userInfo?[EditorCommandUserInfo.inspectionMessage] as? String {
                    whitespaceInspectorMessage = msg
                }
            }
            .onChange(of: appUpdateManager.automaticPromptToken) { _, _ in
                if appUpdateManager.consumeAutomaticPromptIfNeeded() {
                    showUpdaterDialog(checkNow: false)
                }
            }
            .onChange(of: appUpdateManager.isInstalling) { _, isInstalling in
                if isInstalling && !showUpdateDialog {
                    showUpdaterDialog(checkNow: false)
                }
            }
            .onChange(of: appUpdateManager.awaitingInstallCompletionAction) { _, awaitingAction in
                if awaitingAction && !showUpdateDialog {
                    showUpdaterDialog(checkNow: false)
                }
            }
    }

    private var rootViewWithPlatformLifecycleObservers: some View {
        rootViewWithStateObservers
#if os(iOS)
            .onReceive(NotificationCenter.default.publisher(for: UIApplication.didBecomeActiveNotification)) { _ in
                handleAppDidBecomeActive()
            }
#elseif os(macOS)
            .onReceive(NotificationCenter.default.publisher(for: NSApplication.didBecomeActiveNotification)) { _ in
                handleAppDidBecomeActive()
            }
            .onReceive(NotificationCenter.default.publisher(for: NSApplication.willResignActiveNotification)) { _ in
                handleAppWillResignActive()
            }
            .onReceive(NotificationCenter.default.publisher(for: NSApplication.willTerminateNotification)) { _ in
                handleAppWillResignActive()
            }
#endif
    }

    private var lifecycleConfiguredRootView: some View {
        rootViewWithPlatformLifecycleObservers
            .onOpenURL { url in
                viewModel.openFile(url: url)
            }
#if os(iOS)
            .onReceive(NotificationCenter.default.publisher(for: UIApplication.willResignActiveNotification)) { _ in
                persistSessionIfReady()
                persistUnsavedDraftSnapshotIfNeeded()
            }
#endif
            .modifier(ModalPresentationModifier(contentView: self))
            .onAppear {
                handleStartupOnAppear()
            }
    }

    private func handleSettingsAndEditorDefaultsOnAppear() {
        let defaults = UserDefaults.standard
        if let saved = defaults.stringArray(forKey: quickSwitcherRecentsDefaultsKey) {
            quickSwitcherRecentItemIDs = saved
        }
        if UserDefaults.standard.object(forKey: "SettingsAutoIndent") == nil {
            autoIndentEnabled = true
        }
#if os(iOS)
        if defaults.object(forKey: "SettingsShowKeyboardAccessoryBarIOS") == nil {
            showKeyboardAccessoryBarIOS = false
        }
#endif
#if os(macOS)
        if defaults.object(forKey: "ShowBracketHelperBarMac") == nil {
            showBracketHelperBarMac = false
        }
#endif
        let completionResetMigrationKey = "SettingsMigrationCompletionResetV1"
        if !defaults.bool(forKey: completionResetMigrationKey) {
            defaults.set(false, forKey: "SettingsCompletionEnabled")
            defaults.set(true, forKey: completionResetMigrationKey)
            isAutoCompletionEnabled = false
        } else {
            isAutoCompletionEnabled = defaults.bool(forKey: "SettingsCompletionEnabled")
        }
        viewModel.isLineWrapEnabled = effectiveLineWrapEnabled
        syncAppleCompletionAvailability()
    }

    private func handleStartupOnAppear() {
        EditorPerformanceMonitor.shared.markFirstPaint()

        if !didRunInitialWindowLayoutSetup {
            // Start with sidebars collapsed only once; otherwise toggles can get reset on layout transitions.
            viewModel.showSidebar = false
            showProjectStructureSidebar = false
#if os(iOS)
            if UIDevice.current.userInterfaceIdiom == .pad && projectSidebarWidth < Double(minimumProjectSidebarWidth) {
                projectSidebarWidth = Double(minimumProjectSidebarWidth)
            }
#endif
            didRunInitialWindowLayoutSetup = true
        }

        applyStartupBehaviorIfNeeded()

        // Keep iOS tab/editor layout stable by forcing Brain Dump off on mobile.
#if os(iOS)
        viewModel.isBrainDumpMode = false
        UserDefaults.standard.set(false, forKey: "BrainDumpModeEnabled")
#else
        if UserDefaults.standard.object(forKey: "BrainDumpModeEnabled") != nil {
            viewModel.isBrainDumpMode = UserDefaults.standard.bool(forKey: "BrainDumpModeEnabled")
        }
#endif

        applyWindowTranslucency(enableTranslucentWindow)
        if !hasSeenWelcomeTourV1 || welcomeTourSeenRelease != WelcomeTourView.releaseID {
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
                showWelcomeTour = true
            }
        }
        if appLaunchCount >= 5 && !hasShownSupportPromptV1 {
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.8) {
                guard !showWelcomeTour, !hasShownSupportPromptV1 else { return }
                hasShownSupportPromptV1 = true
                showSupportPromptSheet = true
            }
        }
    }

#if os(macOS)
    private func handleWindowDisappear() {
        completionDebounceTask?.cancel()
        completionTask?.cancel()
        lastCompletionTriggerSignature = ""
        pendingHighlightRefresh?.cancel()
        pendingLargeFileModeReevaluation?.cancel()
        completionCache.removeAll(keepingCapacity: false)
        if let number = hostWindowNumber,
           let window = NSApp.window(withWindowNumber: number),
           let delegate = windowCloseConfirmationDelegate,
           window.delegate === delegate {
            window.delegate = delegate.forwardedDelegate
        }
        windowCloseConfirmationDelegate = nil
        if let number = hostWindowNumber {
            WindowViewModelRegistry.shared.unregister(windowNumber: number)
        }
    }
#endif

    private func scheduleHighlightRefresh(delay: TimeInterval = 0.05) {
        pendingHighlightRefresh?.cancel()
        let work = DispatchWorkItem {
            highlightRefreshToken &+= 1
        }
        pendingHighlightRefresh = work
        DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: work)
    }

#if !os(macOS)
    private func shouldThrottleHeavyEditorFeatures(in nsText: NSString? = nil) -> Bool {
        if effectiveLargeFileModeEnabled { return true }
        let length = nsText?.length ?? currentDocumentUTF16Length
        return length >= EditorPerformanceThresholds.heavyFeatureUTF16Length
    }
#endif

    private struct ModalPresentationModifier: ViewModifier {
        let contentView: ContentView

#if os(iOS)
        private var isiPhone: Bool {
            UIDevice.current.userInterfaceIdiom == .phone
        }

        private var findReplaceSheetMaxWidth: CGFloat? {
            isiPhone ? nil : 460
        }

        private var findReplaceSheetDetents: Set<PresentationDetent> {
            isiPhone ? [.height(448), .medium] : [.height(560)]
        }

        private var findInFilesSheetDetents: Set<PresentationDetent> {
            isiPhone ? [.height(540), .medium] : [.height(700), .large]
        }

        @ViewBuilder
        private var findReplaceSheetContent: some View {
            FindReplacePanel(
                findQuery: contentView.$findQuery,
                replaceQuery: contentView.$replaceQuery,
                useRegex: contentView.$findUsesRegex,
                caseSensitive: contentView.$findCaseSensitive,
                matchCount: contentView.$findMatchCount,
                statusMessage: contentView.$findStatusMessage,
                onPreviewChanged: { contentView.refreshFindPreview() },
                onFindNext: {
                    contentView.findNext()
                    contentView.refreshFindMatchCount()
                },
                onJumpToMatch: { contentView.jumpToCurrentFindMatch() },
                onReplace: {
                    contentView.replaceSelection()
                    contentView.refreshFindPreview()
                },
                onReplaceAll: {
                    contentView.replaceAll()
                    contentView.refreshFindPreview()
                },
                onClose: { contentView.showFindReplace = false }
            )
            .frame(maxWidth: findReplaceSheetMaxWidth)
            .presentationDetents(findReplaceSheetDetents)
            .presentationDragIndicator(.visible)
            .presentationContentInteraction(.scrolls)
        }

        @ViewBuilder
        private var findInFilesSheetContent: some View {
            FindInFilesPanel(
                query: contentView.$findInFilesQuery,
                caseSensitive: contentView.$findInFilesCaseSensitive,
                results: contentView.findInFilesResults,
                statusMessage: contentView.findInFilesStatusMessage,
                sourceMessage: contentView.findInFilesSourceMessage,
                onSearch: { contentView.startFindInFiles() },
                onClear: { contentView.clearFindInFiles() },
                onSelect: { contentView.selectFindInFilesMatch($0) },
                onClose: { contentView.showFindInFiles = false }
            )
            .presentationDetents(findInFilesSheetDetents)
            .presentationDragIndicator(.visible)
            .presentationContentInteraction(.scrolls)
        }
#endif

#if !os(macOS)
        private func applyingFindReplaceSheet(to view: AnyView) -> AnyView {
            AnyView(view.sheet(isPresented: contentView.$showFindReplace) {
#if canImport(UIKit)
                findReplaceSheetContent
#else
                FindReplacePanel(
                    findQuery: contentView.$findQuery,
                    replaceQuery: contentView.$replaceQuery,
                    useRegex: contentView.$findUsesRegex,
                    caseSensitive: contentView.$findCaseSensitive,
                    matchCount: contentView.$findMatchCount,
                    statusMessage: contentView.$findStatusMessage,
                    onPreviewChanged: { contentView.refreshFindPreview() },
                    onFindNext: {
                        contentView.findNext()
                        contentView.refreshFindMatchCount()
                    },
                    onJumpToMatch: { contentView.jumpToCurrentFindMatch() },
                    onReplace: {
                        contentView.replaceSelection()
                        contentView.refreshFindPreview()
                    },
                    onReplaceAll: {
                        contentView.replaceAll()
                        contentView.refreshFindPreview()
                    },
                    onClose: { contentView.showFindReplace = false }
                )
                .frame(width: 420)
#endif
            })
        }
#endif

#if canImport(UIKit)
        private func applyingSettingsSheet(to view: AnyView) -> AnyView {
            AnyView(view.sheet(isPresented: contentView.$showSettingsSheet) {
                ConfiguredSettingsView(
                    supportsOpenInTabs: false,
                    supportsTranslucency: false,
                    editorViewModel: contentView.viewModel,
                    supportPurchaseManager: contentView.supportPurchaseManager,
                    appUpdateManager: contentView.appUpdateManager
                )
#if os(iOS)
                .presentationDetents(contentView.settingsSheetDetents)
                .presentationDragIndicator(.visible)
                .presentationContentInteraction(.scrolls)
#endif
            })
        }

        private func applyingProjectFolderPickerSheet(to view: AnyView) -> AnyView {
            AnyView(view.sheet(isPresented: contentView.$showProjectFolderPicker) {
                ProjectFolderPicker(
                    onPick: { url in
                        contentView.setProjectFolder(url)
                        contentView.$showProjectFolderPicker.wrappedValue = false
                    },
                    onCancel: { contentView.$showProjectFolderPicker.wrappedValue = false }
                )
            })
        }
#endif

        private func applyingQuickSwitcherSheet(to view: AnyView) -> AnyView {
            AnyView(view.sheet(isPresented: contentView.$showQuickSwitcher) {
                QuickFileSwitcherPanel(
                    query: contentView.$quickSwitcherQuery,
                    items: contentView.quickSwitcherItems,
                    statusMessage: contentView.quickSwitcherStatusMessage,
                    onSelect: { contentView.selectQuickSwitcherItem($0) },
                    onTogglePin: { contentView.toggleQuickSwitcherPin($0) }
                )
            })
        }

        private func applyingCodeSnapshotSheet(to view: AnyView) -> AnyView {
            AnyView(view.sheet(item: contentView.$codeSnapshotPayload) { payload in
                CodeSnapshotComposerView(payload: payload)
            })
        }

        private func applyingFindInFilesSheet(to view: AnyView) -> AnyView {
            AnyView(view.sheet(isPresented: contentView.$showFindInFiles) {
#if os(iOS)
                findInFilesSheetContent
#else
                FindInFilesPanel(
                    query: contentView.$findInFilesQuery,
                    caseSensitive: contentView.$findInFilesCaseSensitive,
                    results: contentView.findInFilesResults,
                    statusMessage: contentView.findInFilesStatusMessage,
                    sourceMessage: contentView.findInFilesSourceMessage,
                    onSearch: { contentView.startFindInFiles() },
                    onClear: { contentView.clearFindInFiles() },
                    onSelect: { contentView.selectFindInFilesMatch($0) },
                    onClose: { contentView.showFindInFiles = false }
                )
#endif
            })
        }

        private func applyingLanguageSheets(to view: AnyView) -> AnyView {
            AnyView(
                view
                .sheet(isPresented: contentView.$showLanguageSetupPrompt) {
                    contentView.languageSetupSheet
                }
                .sheet(isPresented: contentView.$showLanguageSearchSheet) {
                    contentView.languageSearchSheet
                }
            )
        }

#if os(iOS)
        private func applyingCompactIOSSheets(to view: AnyView) -> AnyView {
            AnyView(
                view
                .sheet(isPresented: contentView.$showCompactSidebarSheet) {
                    NavigationStack {
                        SidebarView(
                            content: contentView.currentContent,
                            language: contentView.currentLanguage,
                            translucentBackgroundEnabled: false
                        )
                            .navigationTitle(Text(NSLocalizedString("Sidebar", comment: "")))
                            .toolbar {
                                ToolbarItem(placement: .topBarTrailing) {
                                    Button(NSLocalizedString("Done", comment: "")) {
                                        contentView.$showCompactSidebarSheet.wrappedValue = false
                                    }
                                }
                            }
                    }
                    .presentationDetents([.medium, .large])
                }
                .sheet(isPresented: contentView.$showCompactProjectSidebarSheet) {
                    NavigationStack {
                        ProjectStructureSidebarView(
                            rootFolderURL: contentView.projectRootFolderURL,
                            nodes: contentView.projectTreeNodes,
                            selectedFileURL: contentView.viewModel.selectedTab?.fileURL,
                            showSupportedFilesOnly: contentView.showSupportedProjectFilesOnly,
                            translucentBackgroundEnabled: false,
                            boundaryEdge: nil,
                            onOpenFile: { contentView.openFileFromToolbar() },
                            onOpenFolder: { contentView.openProjectFolder() },
                            onToggleSupportedFilesOnly: { contentView.showSupportedProjectFilesOnly = $0 },
                            onOpenProjectFile: { contentView.openProjectFile(url: $0) },
                            onRefreshTree: { contentView.refreshProjectBrowserState() },
                            onCreateProjectFile: { contentView.startProjectItemCreation(kind: .file, in: $0) },
                            onCreateProjectFolder: { contentView.startProjectItemCreation(kind: .folder, in: $0) },
                            onRenameProjectItem: { contentView.startProjectItemRename($0) },
                            onDuplicateProjectItem: { contentView.duplicateProjectItem($0) },
                            onDeleteProjectItem: { contentView.requestDeleteProjectItem($0) },
                            revealURL: contentView.projectTreeRevealURL
                        )
                        .navigationTitle(Text(NSLocalizedString("Project Structure", comment: "")))
                        .toolbar {
                            ToolbarItem(placement: .topBarTrailing) {
                                Button(NSLocalizedString("Done", comment: "")) {
                                    contentView.$showCompactProjectSidebarSheet.wrappedValue = false
                                }
                            }
                        }
                    }
                    .presentationDetents([.medium, .large])
                }
                .sheet(isPresented: contentView.markdownPreviewSheetPresentationBinding) {
                    NavigationStack {
                        contentView.markdownPreviewPane
                            .navigationTitle(Text(NSLocalizedString("Markdown Preview", comment: "")))
                            .navigationBarTitleDisplayMode(.inline)
                            .toolbar {
                                ToolbarItem(placement: .topBarTrailing) {
                                    Button(NSLocalizedString("Done", comment: "")) {
                                        contentView.showMarkdownPreviewPane = false
                                    }
                                }
                            }
                    }
                    .presentationDetents([.fraction(0.35), .medium, .large], selection: contentView.$markdownPreviewSheetDetent)
                    .presentationDragIndicator(.visible)
                    .presentationContentInteraction(.scrolls)
                }
            )
        }
#endif

        func body(content: Content) -> some View {
            let baseContent = AnyView(content)
#if !os(macOS)
            let withFindReplace = applyingFindReplaceSheet(to: baseContent)
#else
            let withFindReplace = baseContent
#endif
#if canImport(UIKit)
            let withSettings = applyingSettingsSheet(to: withFindReplace)
#else
            let withSettings = withFindReplace
#endif
#if os(iOS)
            let withCompactSheets = applyingCompactIOSSheets(to: withSettings)
#else
            let withCompactSheets = withSettings
#endif
#if canImport(UIKit)
            let withProjectPicker = applyingProjectFolderPickerSheet(to: withCompactSheets)
#else
            let withProjectPicker = AnyView(withCompactSheets)
#endif
            let withQuickSwitcher = applyingQuickSwitcherSheet(to: withProjectPicker)
            let withCodeSnapshot = applyingCodeSnapshotSheet(to: withQuickSwitcher)
            let withFindInFiles = applyingFindInFilesSheet(to: withCodeSnapshot)
            let modalRoot = applyingLanguageSheets(to: withFindInFiles)
            modalRoot
#if os(macOS)
                .background(
                    WelcomeTourWindowPresenter(
                        isPresented: contentView.$showWelcomeTour,
                        makeContent: {
                            WelcomeTourView {
                                contentView.$hasSeenWelcomeTourV1.wrappedValue = true
                                contentView.$welcomeTourSeenRelease.wrappedValue = WelcomeTourView.releaseID
                                contentView.$showWelcomeTour.wrappedValue = false
                            }
                        }
                    )
                    .frame(width: 0, height: 0)
                )
#else
                .sheet(isPresented: contentView.$showWelcomeTour) {
                    WelcomeTourView {
                        contentView.$hasSeenWelcomeTourV1.wrappedValue = true
                        contentView.$welcomeTourSeenRelease.wrappedValue = WelcomeTourView.releaseID
                        contentView.$showWelcomeTour.wrappedValue = false
                    }
                }
#endif
                .sheet(isPresented: contentView.$showEditorHelp) {
                    EditorHelpView {
                        contentView.$showEditorHelp.wrappedValue = false
                    }
                }
                .sheet(isPresented: contentView.$showSupportPromptSheet) {
                    SupportPromptSheetView {
                        contentView.$showSupportPromptSheet.wrappedValue = false
                    }
                    .environmentObject(contentView.supportPurchaseManager)
                }
                .sheet(isPresented: contentView.$showUpdateDialog) {
                    AppUpdaterDialog(isPresented: contentView.$showUpdateDialog)
                        .environmentObject(contentView.appUpdateManager)
                }
                .confirmationDialog("Save changes before closing?", isPresented: contentView.$showUnsavedCloseDialog, titleVisibility: .visible) {
                    Button("Save") { contentView.saveAndClosePendingTab() }
                    Button("Don't Save", role: .destructive) { contentView.discardAndClosePendingTab() }
                    Button("Cancel", role: .cancel) {
                        contentView.$pendingCloseTabID.wrappedValue = nil
                    }
                } message: {
                    if let pendingCloseTabID = contentView.pendingCloseTabID,
                       let tab = contentView.viewModel.tabs.first(where: { $0.id == pendingCloseTabID }) {
                        Text("\"\(tab.name)\" has unsaved changes.")
                    } else {
                        Text("This file has unsaved changes.")
                    }
                }
                .confirmationDialog("Are you sure you want to close all tabs?", isPresented: contentView.$showCloseAllTabsDialog, titleVisibility: .visible) {
                    Button("Close All Tabs", role: .destructive) {
                        contentView.closeAllTabsFromToolbar()
                    }
                    Button("Cancel", role: .cancel) { }
                }
                .confirmationDialog("File changed on disk", isPresented: contentView.$showExternalConflictDialog, titleVisibility: .visible) {
                    if let conflict = contentView.viewModel.pendingExternalFileConflict {
                        Button("Reload from Disk", role: .destructive) {
                            contentView.viewModel.resolveExternalConflictByReloadingDisk(tabID: conflict.tabID)
                        }
                        Button("Keep Local and Save") {
                            contentView.viewModel.resolveExternalConflictByKeepingLocal(tabID: conflict.tabID)
                        }
                        Button("Compare") {
                            Task {
                                if let snapshot = await contentView.viewModel.externalConflictComparisonSnapshot(tabID: conflict.tabID) {
                                    await MainActor.run {
                                        contentView.externalConflictCompareSnapshot = snapshot
                                        contentView.showExternalConflictCompareSheet = true
                                    }
                                }
                            }
                        }
                    }
                    Button("Cancel", role: .cancel) { }
                } message: {
                    if let conflict = contentView.viewModel.pendingExternalFileConflict {
                        if let modified = conflict.diskModifiedAt {
                            Text("\"\(conflict.fileURL.lastPathComponent)\" changed on disk at \(modified.formatted(date: .abbreviated, time: .shortened)).")
                        } else {
                            Text("\"\(conflict.fileURL.lastPathComponent)\" changed on disk.")
                        }
                    } else {
                        Text("The file changed on disk while you had unsaved edits.")
                    }
                }
                .confirmationDialog(
                    contentView.viewModel.pendingRemoteSaveIssue?.isConflict == true
                        ? "Remote file changed"
                        : (contentView.viewModel.pendingRemoteSaveIssue?.requiresReconnect == true
                            ? "Remote session unavailable"
                            : "Remote save failed"),
                    isPresented: contentView.$showRemoteSaveIssueDialog,
                    titleVisibility: .visible
                ) {
                    if let issue = contentView.viewModel.pendingRemoteSaveIssue {
                        if issue.isConflict {
                            Button("Compare") {
                                Task {
                                    if let snapshot = await contentView.viewModel.remoteConflictComparisonSnapshot(tabID: issue.tabID) {
                                        await MainActor.run {
                                            contentView.remoteConflictCompareSnapshot = snapshot
                                            contentView.showRemoteConflictCompareSheet = true
                                        }
                                    }
                                }
                            }
                            Button("Reload from Remote", role: .destructive) {
                                contentView.viewModel.reloadRemoteDocumentAfterConflict(tabID: issue.tabID)
                            }
                        } else if issue.requiresReconnect {
                            Button("Detach Broker", role: .destructive) {
                                contentView.viewModel.detachRemoteBrokerAfterSaveIssue()
                            }
                        } else {
                            Button("Try Save Again") {
                                contentView.viewModel.retryRemoteSave(tabID: issue.tabID)
                            }
                        }
                    }
                    Button("Dismiss", role: .cancel) {
                        contentView.viewModel.dismissRemoteSaveIssue()
                    }
                } message: {
                    if let issue = contentView.viewModel.pendingRemoteSaveIssue {
                        Text(issue.requiresReconnect ? issue.recoveryGuidance : issue.detail)
                    } else {
                        Text("The remote document could not be saved.")
                    }
                }
                .sheet(isPresented: contentView.$showExternalConflictCompareSheet, onDismiss: {
                    contentView.externalConflictCompareSnapshot = nil
                }) {
                    if let snapshot = contentView.externalConflictCompareSnapshot {
                        NavigationStack {
                            VStack(spacing: 12) {
                                Text("Compare Local vs Disk: \(snapshot.fileName)")
                                    .font(.headline)
                                HStack(spacing: 10) {
                                    VStack(alignment: .leading, spacing: 6) {
                                        Text("Local")
                                            .font(.subheadline.weight(.semibold))
                                        TextEditor(text: .constant(snapshot.localContent))
                                            .font(.system(.footnote, design: .monospaced))
                                            .disabled(true)
                                    }
                                    VStack(alignment: .leading, spacing: 6) {
                                        Text("Disk")
                                            .font(.subheadline.weight(.semibold))
                                        TextEditor(text: .constant(snapshot.diskContent))
                                            .font(.system(.footnote, design: .monospaced))
                                            .disabled(true)
                                    }
                                }
                                .frame(maxHeight: .infinity)
                                HStack {
                                    Button("Use Disk", role: .destructive) {
                                        if let conflict = contentView.viewModel.pendingExternalFileConflict {
                                            contentView.viewModel.resolveExternalConflictByReloadingDisk(tabID: conflict.tabID)
                                        }
                                        contentView.showExternalConflictCompareSheet = false
                                    }
                                    Spacer()
                                    Button("Keep Local and Save") {
                                        if let conflict = contentView.viewModel.pendingExternalFileConflict {
                                            contentView.viewModel.resolveExternalConflictByKeepingLocal(tabID: conflict.tabID)
                                        }
                                        contentView.showExternalConflictCompareSheet = false
                                    }
                                }
                            }
                            .padding(16)
                            .navigationTitle("External Change")
                        }
                    }
                }
                .sheet(isPresented: contentView.$showRemoteConflictCompareSheet, onDismiss: {
                    contentView.remoteConflictCompareSnapshot = nil
                }) {
                    if let snapshot = contentView.remoteConflictCompareSnapshot {
                        NavigationStack {
                            VStack(spacing: 12) {
                                Text("Compare Local vs Remote: \(snapshot.fileName)")
                                    .font(.headline)
                                HStack(spacing: 10) {
                                    VStack(alignment: .leading, spacing: 6) {
                                        Text("Local")
                                            .font(.subheadline.weight(.semibold))
                                        TextEditor(text: .constant(snapshot.localContent))
                                            .font(.system(.footnote, design: .monospaced))
                                            .disabled(true)
                                    }
                                    VStack(alignment: .leading, spacing: 6) {
                                        Text("Remote")
                                            .font(.subheadline.weight(.semibold))
                                        TextEditor(text: .constant(snapshot.remoteContent))
                                            .font(.system(.footnote, design: .monospaced))
                                            .disabled(true)
                                    }
                                }
                                .frame(maxHeight: .infinity)
                                HStack {
                                    Button("Reload from Remote", role: .destructive) {
                                        contentView.viewModel.reloadRemoteDocumentAfterConflict(tabID: snapshot.tabID)
                                        contentView.showRemoteConflictCompareSheet = false
                                    }
                                    Spacer()
                                    Button("Close") {
                                        contentView.showRemoteConflictCompareSheet = false
                                    }
                                }
                            }
                            .padding(16)
                            .navigationTitle("Remote Conflict")
                        }
                    }
                }
                .confirmationDialog("Clear editor content?", isPresented: contentView.$showClearEditorConfirmDialog, titleVisibility: .visible) {
                    Button("Clear", role: .destructive) { contentView.clearEditorContent() }
                    Button("Cancel", role: .cancel) {}
                } message: {
                    Text("This will remove all text in the current editor.")
                }
                .alert("Can’t Open File", isPresented: contentView.$showUnsupportedFileAlert) {
                    Button("OK", role: .cancel) { }
                } message: {
                    Text(String(
                        format: NSLocalizedString(
                            "The file \"%@\" is not supported and can’t be opened.",
                            comment: "Unsupported file alert message"
                        ),
                        contentView.unsupportedFileName
                    ))
                }
                .alert(contentView.projectItemCreationKind.title, isPresented: contentView.$showProjectItemCreationPrompt) {
                    TextField(
                        contentView.projectItemCreationKind.namePlaceholder,
                        text: contentView.$projectItemCreationNameDraft
                    )
                    Button("Create") { contentView.confirmProjectItemCreation() }
                    Button("Cancel", role: .cancel) { contentView.cancelProjectItemCreation() }
                } message: {
                    Text(NSLocalizedString("Choose a name for the new item.", comment: "Project item creation prompt message"))
                }
                .alert(NSLocalizedString("Rename Item", comment: "Project item rename alert title"), isPresented: contentView.$showProjectItemRenamePrompt) {
                    TextField(
                        NSLocalizedString("Name", comment: "Project item rename name field placeholder"),
                        text: contentView.$projectItemRenameNameDraft
                    )
                    Button("Rename") { contentView.confirmProjectItemRename() }
                    Button("Cancel", role: .cancel) { contentView.cancelProjectItemRename() }
                } message: {
                    Text(NSLocalizedString("Enter a new name.", comment: "Project item rename prompt message"))
                }
                .confirmationDialog(
                    NSLocalizedString("Delete Item?", comment: "Project item delete confirmation title"),
                    isPresented: contentView.$showProjectItemDeleteConfirmation,
                    titleVisibility: .visible
                ) {
                    Button("Delete", role: .destructive) { contentView.confirmDeleteProjectItem() }
                    Button("Cancel", role: .cancel) { contentView.cancelDeleteProjectItem() }
                } message: {
                    if !contentView.projectItemDeleteTargetName.isEmpty {
                        Text(
                            String(
                                format: NSLocalizedString(
                                    "This will permanently delete \"%@\".",
                                    comment: "Project item delete confirmation message"
                                ),
                                contentView.projectItemDeleteTargetName
                            )
                        )
                    }
                }
                .alert(NSLocalizedString("Can’t Complete Action", comment: "Project item operation error alert title"), isPresented: contentView.$showProjectItemOperationErrorAlert) {
                    Button("OK", role: .cancel) { }
                } message: {
                    Text(contentView.projectItemOperationErrorMessage)
                }
#if canImport(UIKit)
                .fileImporter(
                    isPresented: contentView.$showIOSFileImporter,
                    allowedContentTypes: [.item],
                    allowsMultipleSelection: true
                ) { result in
                    contentView.handleIOSImportResult(result)
                }
                .fileExporter(
                    isPresented: contentView.$showIOSFileExporter,
                    document: contentView.iosExportDocument,
                    contentType: .plainText,
                    defaultFilename: contentView.iosExportFilename
                ) { result in
                    contentView.handleIOSExportResult(result)
                }
#endif
        }
    }

    private var shouldUseSplitView: Bool {
#if os(macOS)
        return viewModel.showSidebar && !brainDumpLayoutEnabled
#else
        // Keep iPhone layout single-column to avoid horizontal clipping.
        return viewModel.showSidebar && !brainDumpLayoutEnabled && horizontalSizeClass == .regular
#endif
    }

    private var themeFormattingRefreshSignature: Int {
        var signature = 0
        if settingsThemeBoldKeywords { signature |= 1 << 0 }
        if settingsThemeItalicComments { signature |= 1 << 1 }
        if settingsThemeUnderlineLinks { signature |= 1 << 2 }
        if settingsThemeBoldMarkdownHeadings { signature |= 1 << 3 }
        return signature
    }

    private var effectiveIndentWidth: Int {
        projectOverrideIndentWidth ?? indentWidth
    }

    private var effectiveLineWrapEnabled: Bool {
        projectOverrideLineWrapEnabled ?? settingsLineWrapEnabled
    }

    private func applyStartupBehaviorIfNeeded() {
        guard !didApplyStartupBehavior else { return }

        if startupBehavior == .forceBlankDocument || startupBehavior == .safeMode {
            viewModel.resetTabsForSessionRestore()
            viewModel.addNewTab()
            projectRootFolderURL = nil
            clearProjectEditorOverrides()
            projectTreeNodes = []
            quickSwitcherProjectFileURLs = []
            stopProjectFolderObservation()
            projectFileIndexSnapshot = .empty
            isProjectFileIndexing = false
            projectFileIndexTask?.cancel()
            projectFileIndexTask = nil
            didApplyStartupBehavior = true
            if startupBehavior != .safeMode {
                persistSessionIfReady()
            }
            return
        }

        if viewModel.tabs.contains(where: { $0.fileURL != nil }) {
            didApplyStartupBehavior = true
            persistSessionIfReady()
            return
        }

        // If both startup toggles are enabled (legacy/default mismatch), prefer session restore.
        let shouldOpenBlankOnStartup = openWithBlankDocument && !reopenLastSession
        if shouldOpenBlankOnStartup {
            viewModel.resetTabsForSessionRestore()
            viewModel.addNewTab()
            projectRootFolderURL = nil
            clearProjectEditorOverrides()
            projectTreeNodes = []
            quickSwitcherProjectFileURLs = []
            stopProjectFolderObservation()
            projectFileIndexSnapshot = .empty
            isProjectFileIndexing = false
            projectFileIndexTask?.cancel()
            projectFileIndexTask = nil
            didApplyStartupBehavior = true
            persistSessionIfReady()
            return
        }

        var restoredSessionTabs = false

        // Restore last session first when enabled.
        if reopenLastSession {
            if projectRootFolderURL == nil, let restoredProjectFolderURL = restoredLastSessionProjectFolderURL() {
                setProjectFolder(restoredProjectFolderURL)
            }
            let urls = restoredLastSessionFileURLs()
            let selectedURL = restoredLastSessionSelectedFileURL()

            if !urls.isEmpty {
                viewModel.resetTabsForSessionRestore()

                for url in urls {
                    viewModel.openFile(url: url)
                }

                if let selectedURL {
                    _ = viewModel.focusTabIfOpen(for: selectedURL)
                }

                restoredSessionTabs = !viewModel.tabs.isEmpty
                if viewModel.tabs.isEmpty {
                    viewModel.addNewTab()
                }
            }
        }

        // Restore unsaved drafts only as fallback when no file session tabs were restored.
        if !restoredSessionTabs, restoreUnsavedDraftSnapshotIfAvailable() {
            didApplyStartupBehavior = true
            persistSessionIfReady()
            return
        }

#if os(iOS)
        // Keep mobile layout in a valid tab state so the file tab bar always has content.
        if viewModel.tabs.isEmpty {
            viewModel.addNewTab()
        }
#endif

        restoreLastSessionViewContextIfAvailable()
        restoreCaretForSelectedSessionFileIfAvailable()
        didApplyStartupBehavior = true
        persistSessionIfReady()
    }

    func persistSessionIfReady() {
        guard didApplyStartupBehavior else { return }
        guard startupBehavior != .safeMode else { return }
        let fileURLs = viewModel.tabs.compactMap { $0.fileURL }
        UserDefaults.standard.set(fileURLs.map(\.absoluteString), forKey: "LastSessionFileURLs")
        UserDefaults.standard.set(viewModel.selectedTab?.fileURL?.absoluteString, forKey: "LastSessionSelectedFileURL")
        persistLastSessionViewContext()
        persistLastSessionProjectFolderURL(projectRootFolderURL)
#if os(iOS)
        persistLastSessionSecurityScopedBookmarks(fileURLs: fileURLs, selectedURL: viewModel.selectedTab?.fileURL)
#elseif os(macOS)
        persistLastSessionSecurityScopedBookmarksMac(fileURLs: fileURLs, selectedURL: viewModel.selectedTab?.fileURL)
#endif
    }

    private func restoredLastSessionFileURLs() -> [URL] {
#if os(macOS)
        let bookmarked = restoreSessionURLsFromSecurityScopedBookmarksMac()
        if !bookmarked.isEmpty {
            return bookmarked
        }
#elseif os(iOS)
        let bookmarked = restoreSessionURLsFromSecurityScopedBookmarks()
        if !bookmarked.isEmpty {
            return bookmarked
        }
#endif
        let stored = UserDefaults.standard.stringArray(forKey: "LastSessionFileURLs") ?? []
        var urls: [URL] = []
        var seen: Set<String> = []
        for raw in stored {
            guard let parsed = restoredSessionURL(from: raw) else { continue }
            let standardized = parsed.standardizedFileURL
            // Only restore files that still exist; avoids empty placeholder tabs on launch.
            guard FileManager.default.fileExists(atPath: standardized.path) else { continue }
            let key = standardized.absoluteString
            if seen.insert(key).inserted {
                urls.append(standardized)
            }
        }
        return urls
    }

    private func restoredLastSessionSelectedFileURL() -> URL? {
#if os(macOS)
        if let bookmarked = restoreSelectedURLFromSecurityScopedBookmarkMac() {
            return bookmarked
        }
#elseif os(iOS)
        if let bookmarked = restoreSelectedURLFromSecurityScopedBookmark() {
            return bookmarked
        }
#endif
        guard let selectedPath = UserDefaults.standard.string(forKey: "LastSessionSelectedFileURL"),
              let selectedURL = restoredSessionURL(from: selectedPath) else {
            return nil
        }
        let standardized = selectedURL.standardizedFileURL
        return FileManager.default.fileExists(atPath: standardized.path) ? standardized : nil
    }

    private func restoredSessionURL(from raw: String) -> URL? {
        // Support both absolute URL strings ("file:///...") and legacy plain paths.
        if let url = URL(string: raw), url.isFileURL {
            return url
        }
        if raw.hasPrefix("/") {
            return URL(fileURLWithPath: raw)
        }
        return nil
    }

    private var lastSessionShowSidebarKey: String { "LastSessionShowSidebarV1" }
    private var lastSessionShowProjectSidebarKey: String { "LastSessionShowProjectSidebarV1" }
    private var lastSessionShowMarkdownPreviewKey: String { "LastSessionShowMarkdownPreviewV1" }
    private var lastSessionCaretByFileURLKey: String { "LastSessionCaretByFileURLV1" }

    private var lastSessionProjectFolderURLKey: String { "LastSessionProjectFolderURL" }

    private func persistLastSessionViewContext() {
        let defaults = UserDefaults.standard
        defaults.set(viewModel.showSidebar, forKey: lastSessionShowSidebarKey)
        defaults.set(showProjectStructureSidebar, forKey: lastSessionShowProjectSidebarKey)
        defaults.set(showMarkdownPreviewPane, forKey: lastSessionShowMarkdownPreviewKey)

        if let selectedURL = viewModel.selectedTab?.fileURL {
            let key = selectedURL.standardizedFileURL.absoluteString
            if !key.isEmpty {
                sessionCaretByFileURL[key] = max(0, lastCaretLocation)
            }
        }
        defaults.set(sessionCaretByFileURL, forKey: lastSessionCaretByFileURLKey)
    }

    private func restoreLastSessionViewContextIfAvailable() {
        let defaults = UserDefaults.standard
        if defaults.object(forKey: lastSessionShowSidebarKey) != nil {
            viewModel.showSidebar = defaults.bool(forKey: lastSessionShowSidebarKey)
        }
        if defaults.object(forKey: lastSessionShowProjectSidebarKey) != nil {
            showProjectStructureSidebar = defaults.bool(forKey: lastSessionShowProjectSidebarKey)
        }
        if defaults.object(forKey: lastSessionShowMarkdownPreviewKey) != nil {
            showMarkdownPreviewPane = defaults.bool(forKey: lastSessionShowMarkdownPreviewKey)
        }
        sessionCaretByFileURL = defaults.dictionary(forKey: lastSessionCaretByFileURLKey) as? [String: Int] ?? [:]
    }

    private func restoreCaretForSelectedSessionFileIfAvailable() {
        guard let selectedURL = viewModel.selectedTab?.fileURL?.standardizedFileURL else { return }
        guard let location = sessionCaretByFileURL[selectedURL.absoluteString], location >= 0 else { return }
        var userInfo: [String: Any] = [
            EditorCommandUserInfo.rangeLocation: location,
            EditorCommandUserInfo.rangeLength: 0,
            EditorCommandUserInfo.focusEditor: true
        ]
#if os(macOS)
        if let hostWindowNumber {
            userInfo[EditorCommandUserInfo.windowNumber] = hostWindowNumber
        }
#endif
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.12) {
            NotificationCenter.default.post(name: .moveCursorToRange, object: nil, userInfo: userInfo)
        }
    }

    private func persistLastSessionProjectFolderURL(_ folderURL: URL?) {
        guard let folderURL else {
            UserDefaults.standard.removeObject(forKey: lastSessionProjectFolderURLKey)
#if os(macOS)
            UserDefaults.standard.removeObject(forKey: macLastSessionProjectFolderBookmarkKey)
#elseif os(iOS)
            UserDefaults.standard.removeObject(forKey: lastSessionProjectFolderBookmarkKey)
#endif
            return
        }

        UserDefaults.standard.set(folderURL.absoluteString, forKey: lastSessionProjectFolderURLKey)
#if os(macOS)
        if let bookmark = makeSecurityScopedBookmarkDataMac(for: folderURL) {
            UserDefaults.standard.set(bookmark, forKey: macLastSessionProjectFolderBookmarkKey)
        } else {
            UserDefaults.standard.removeObject(forKey: macLastSessionProjectFolderBookmarkKey)
        }
#elseif os(iOS)
        if let bookmark = makeSecurityScopedBookmarkData(for: folderURL) {
            UserDefaults.standard.set(bookmark, forKey: lastSessionProjectFolderBookmarkKey)
        } else {
            UserDefaults.standard.removeObject(forKey: lastSessionProjectFolderBookmarkKey)
        }
#endif
    }

    private func restoredLastSessionProjectFolderURL() -> URL? {
#if os(macOS)
        if let bookmarked = restoreProjectFolderURLFromSecurityScopedBookmarkMac() {
            return bookmarked
        }
#elseif os(iOS)
        if let bookmarked = restoreProjectFolderURLFromSecurityScopedBookmark() {
            return bookmarked
        }
#endif
        guard let raw = UserDefaults.standard.string(forKey: lastSessionProjectFolderURLKey),
              let parsed = restoredSessionURL(from: raw) else {
            return nil
        }
        let standardized = parsed.standardizedFileURL
        return FileManager.default.fileExists(atPath: standardized.path) ? standardized : nil
    }

#if os(macOS)
    private var macLastSessionBookmarksKey: String { "MacLastSessionFileBookmarks" }
    private var macLastSessionSelectedBookmarkKey: String { "MacLastSessionSelectedFileBookmark" }
    private var macLastSessionProjectFolderBookmarkKey: String { "MacLastSessionProjectFolderBookmark" }

    private func persistLastSessionSecurityScopedBookmarksMac(fileURLs: [URL], selectedURL: URL?) {
        let bookmarkData = fileURLs.compactMap { makeSecurityScopedBookmarkDataMac(for: $0) }
        UserDefaults.standard.set(bookmarkData, forKey: macLastSessionBookmarksKey)
        if let selectedURL, let selectedData = makeSecurityScopedBookmarkDataMac(for: selectedURL) {
            UserDefaults.standard.set(selectedData, forKey: macLastSessionSelectedBookmarkKey)
        } else {
            UserDefaults.standard.removeObject(forKey: macLastSessionSelectedBookmarkKey)
        }
    }

    private func restoreSessionURLsFromSecurityScopedBookmarksMac() -> [URL] {
        guard let saved = UserDefaults.standard.array(forKey: macLastSessionBookmarksKey) as? [Data], !saved.isEmpty else {
            return []
        }
        var urls: [URL] = []
        var seen: Set<String> = []
        for data in saved {
            guard let url = resolveSecurityScopedBookmarkMac(data) else { continue }
            let standardized = url.standardizedFileURL
            guard FileManager.default.fileExists(atPath: standardized.path) else { continue }
            let key = standardized.absoluteString
            if seen.insert(key).inserted {
                urls.append(standardized)
            }
        }
        return urls
    }

    private func restoreSelectedURLFromSecurityScopedBookmarkMac() -> URL? {
        guard let data = UserDefaults.standard.data(forKey: macLastSessionSelectedBookmarkKey),
              let resolved = resolveSecurityScopedBookmarkMac(data) else {
            return nil
        }
        let standardized = resolved.standardizedFileURL
        return FileManager.default.fileExists(atPath: standardized.path) ? standardized : nil
    }

    private func restoreProjectFolderURLFromSecurityScopedBookmarkMac() -> URL? {
        guard let data = UserDefaults.standard.data(forKey: macLastSessionProjectFolderBookmarkKey),
              let resolved = resolveSecurityScopedBookmarkMac(data) else {
            return nil
        }
        let standardized = resolved.standardizedFileURL
        return FileManager.default.fileExists(atPath: standardized.path) ? standardized : nil
    }

    private func makeSecurityScopedBookmarkDataMac(for url: URL) -> Data? {
        let didStartScopedAccess = url.startAccessingSecurityScopedResource()
        defer {
            if didStartScopedAccess {
                url.stopAccessingSecurityScopedResource()
            }
        }
        do {
            return try url.bookmarkData(
                options: [.withSecurityScope],
                includingResourceValuesForKeys: nil,
                relativeTo: nil
            )
        } catch {
            return nil
        }
    }

    private func resolveSecurityScopedBookmarkMac(_ data: Data) -> URL? {
        var isStale = false
        guard let resolved = try? URL(
            resolvingBookmarkData: data,
            options: [.withSecurityScope, .withoutUI],
            relativeTo: nil,
            bookmarkDataIsStale: &isStale
        ) else {
            return nil
        }
        return resolved
    }
#endif

    private var unsavedDraftSnapshotRegistryKey: String { "UnsavedDraftSnapshotRegistryV1" }
    private var unsavedDraftSnapshotKey: String { "UnsavedDraftSnapshotV2.\(recoverySnapshotIdentifier)" }
    private var maxPersistedDraftTabs: Int { 20 }
    private var maxPersistedDraftUTF16Length: Int { 2_000_000 }

    private func persistUnsavedDraftSnapshotIfNeeded() {
        let defaults = UserDefaults.standard
        let dirtyTabs = viewModel.tabs.filter(\.isDirty)
        var registry = defaults.stringArray(forKey: unsavedDraftSnapshotRegistryKey) ?? []

        guard !dirtyTabs.isEmpty else {
            defaults.removeObject(forKey: unsavedDraftSnapshotKey)
            registry.removeAll { $0 == unsavedDraftSnapshotKey }
            defaults.set(registry, forKey: unsavedDraftSnapshotRegistryKey)
            return
        }

        var savedTabs: [SavedDraftTabSnapshot] = []
        savedTabs.reserveCapacity(min(dirtyTabs.count, maxPersistedDraftTabs))
        for tab in dirtyTabs.prefix(maxPersistedDraftTabs) {
            let content = tab.content
            let nsContent = content as NSString
            let clampedContent = nsContent.length > maxPersistedDraftUTF16Length
                ? nsContent.substring(to: maxPersistedDraftUTF16Length)
                : content
            savedTabs.append(
                SavedDraftTabSnapshot(
                    name: tab.name,
                    content: clampedContent,
                    language: tab.language,
                    fileURLString: tab.fileURL?.absoluteString
                )
            )
        }

        let selectedIndex: Int? = {
            guard let selectedID = viewModel.selectedTabID else { return nil }
            return dirtyTabs.firstIndex(where: { $0.id == selectedID })
        }()

        let snapshot = SavedDraftSnapshot(tabs: savedTabs, selectedIndex: selectedIndex, createdAt: Date())
        guard let encoded = try? JSONEncoder().encode(snapshot) else { return }
        defaults.set(encoded, forKey: unsavedDraftSnapshotKey)
        if !registry.contains(unsavedDraftSnapshotKey) {
            registry.append(unsavedDraftSnapshotKey)
            defaults.set(registry, forKey: unsavedDraftSnapshotRegistryKey)
        }
    }

    private func restoreUnsavedDraftSnapshotIfAvailable() -> Bool {
        let defaults = UserDefaults.standard
        let keys = defaults.stringArray(forKey: unsavedDraftSnapshotRegistryKey) ?? []
        guard !keys.isEmpty else { return false }

        var snapshots: [SavedDraftSnapshot] = []
        for key in keys {
            guard let data = defaults.data(forKey: key),
                  let snapshot = try? JSONDecoder().decode(SavedDraftSnapshot.self, from: data),
                  !snapshot.tabs.isEmpty else {
                continue
            }
            snapshots.append(snapshot)
        }
        guard !snapshots.isEmpty else { return false }

        snapshots.sort { $0.createdAt < $1.createdAt }
        let mergedTabs = snapshots.flatMap(\.tabs)
        guard !mergedTabs.isEmpty else { return false }

        let restoredTabs = mergedTabs.map { saved in
            EditorViewModel.RestoredTabSnapshot(
                name: saved.name,
                content: saved.content,
                language: saved.language,
                fileURL: saved.fileURLString.flatMap(URL.init(string:)),
                languageLocked: true,
                isDirty: true,
                lastSavedFingerprint: nil,
                lastKnownFileModificationDate: nil
            )
        }
        viewModel.restoreTabsFromSnapshot(restoredTabs, selectedIndex: nil)

        for key in keys {
            defaults.removeObject(forKey: key)
        }
        defaults.removeObject(forKey: unsavedDraftSnapshotRegistryKey)
        return true
    }

#if os(iOS)
    private var lastSessionBookmarksKey: String { "LastSessionFileBookmarks" }
    private var lastSessionSelectedBookmarkKey: String { "LastSessionSelectedFileBookmark" }
    private var lastSessionProjectFolderBookmarkKey: String { "LastSessionProjectFolderBookmark" }

    private func persistLastSessionSecurityScopedBookmarks(fileURLs: [URL], selectedURL: URL?) {
        let bookmarkData = fileURLs.compactMap { makeSecurityScopedBookmarkData(for: $0) }
        UserDefaults.standard.set(bookmarkData, forKey: lastSessionBookmarksKey)
        if let selectedURL, let selectedData = makeSecurityScopedBookmarkData(for: selectedURL) {
            UserDefaults.standard.set(selectedData, forKey: lastSessionSelectedBookmarkKey)
        } else {
            UserDefaults.standard.removeObject(forKey: lastSessionSelectedBookmarkKey)
        }
    }

    private func restoreSessionURLsFromSecurityScopedBookmarks() -> [URL] {
        guard let saved = UserDefaults.standard.array(forKey: lastSessionBookmarksKey) as? [Data], !saved.isEmpty else {
            return []
        }
        var urls: [URL] = []
        var seen: Set<String> = []
        for data in saved {
            guard let url = resolveSecurityScopedBookmark(data) else { continue }
            let key = url.standardizedFileURL.absoluteString
            if seen.insert(key).inserted {
                urls.append(url)
            }
        }
        return urls
    }

    private func restoreSelectedURLFromSecurityScopedBookmark() -> URL? {
        guard let data = UserDefaults.standard.data(forKey: lastSessionSelectedBookmarkKey) else { return nil }
        return resolveSecurityScopedBookmark(data)
    }

    private func restoreProjectFolderURLFromSecurityScopedBookmark() -> URL? {
        guard let data = UserDefaults.standard.data(forKey: lastSessionProjectFolderBookmarkKey),
              let resolved = resolveSecurityScopedBookmark(data) else { return nil }
        let standardized = resolved.standardizedFileURL
        return FileManager.default.fileExists(atPath: standardized.path) ? standardized : nil
    }

    private func makeSecurityScopedBookmarkData(for url: URL) -> Data? {
        do {
            return try url.bookmarkData(
                options: [],
                includingResourceValuesForKeys: nil,
                relativeTo: nil
            )
        } catch {
            return nil
        }
    }

    private func resolveSecurityScopedBookmark(_ data: Data) -> URL? {
        var isStale = false
        guard let resolved = try? URL(
            resolvingBookmarkData: data,
            options: [.withoutUI],
            relativeTo: nil,
            bookmarkDataIsStale: &isStale
        ) else {
            return nil
        }
        return resolved
    }
#endif

    // Sidebar shows a lightweight table of contents (TOC) derived from the current document.
    @ViewBuilder
    var sidebarView: some View {
        if viewModel.showSidebar && !brainDumpLayoutEnabled {
            SidebarView(
                content: sidebarTOCContent,
                language: currentLanguage,
                translucentBackgroundEnabled: enableTranslucentWindow
            )
                .frame(minWidth: 200, idealWidth: 250, maxWidth: 600)
                .safeAreaInset(edge: .bottom) {
#if os(iOS)
                    iOSHorizontalSurfaceDivider
#else
                    Divider()
#endif
                }
                .background(editorSurfaceBackgroundStyle)
        } else {
            EmptyView()
        }
    }

    // Bindings that resolve to the active tab (if present) or fallback single-document state.
    var currentContentBinding: Binding<String> {
        if let selectedID = viewModel.selectedTabID,
           viewModel.selectedTab != nil {
            return Binding(
                get: {
                    viewModel.selectedTab?.content ?? singleContent
                },
                set: { newValue in
                    guard viewModel.selectedTab?.isReadOnlyPreview != true else { return }
                    viewModel.updateTabContent(tabID: selectedID, content: newValue)
                }
            )
        } else {
            return $singleContent
        }
    }

    var currentLanguageBinding: Binding<String> {
        if let selectedID = viewModel.selectedTabID,
           viewModel.selectedTab != nil {
            return Binding(
                get: {
                    viewModel.selectedTab?.language ?? singleLanguage
                },
                set: { newValue in
                    viewModel.updateTabLanguage(tabID: selectedID, language: newValue)
                }
            )
        } else {
            return $singleLanguage
        }
    }

    var currentLanguagePickerBinding: Binding<String> {
        Binding(
            get: { currentLanguageBinding.wrappedValue },
            set: { newValue in
                if let tab = viewModel.selectedTab {
                    viewModel.updateTabLanguage(tabID: tab.id, language: newValue)
                } else {
                    singleLanguage = newValue
                }
            }
        )
    }

    var currentContent: String { currentContentBinding.wrappedValue }
    var currentLanguage: String { currentLanguageBinding.wrappedValue }

    private var currentDocumentUTF16Length: Int {
        if let tab = viewModel.selectedTab {
            return tab.contentUTF16Length
        }
        return (singleContent as NSString).length
    }

    private var effectiveLargeFileModeEnabled: Bool {
        if largeFileModeEnabled { return true }
        if droppedFileLoadInProgress { return true }
        if viewModel.selectedTab?.isLargeFileCandidate == true { return true }
        return currentDocumentUTF16Length >= 300_000
    }

    private var isSelectedTabReadOnlyPreview: Bool {
        viewModel.selectedTab?.isReadOnlyPreview == true
    }

    private var shouldUseDeferredLargeFileOpenMode: Bool {
        largeFileOpenModeRaw == "deferred" || largeFileOpenModeRaw == "plainText"
    }

    private var currentLargeFileOpenModeLabel: String {
        switch largeFileOpenModeRaw {
        case "standard":
            return "Standard"
        case "plainText":
            return "Plain Text"
        default:
            return "Deferred"
        }
    }

    private var largeFileStatusBadgeText: String {
        guard effectiveLargeFileModeEnabled else { return "" }
        return "Large File • \(currentLargeFileOpenModeLabel)"
    }

    private var remoteSessionStatusBadgeText: String {
        guard remoteSessionsEnabled else { return "" }
        if remoteSessionStore.runtimeState == .failed, remoteSessionStore.isBrokerClientAttached {
            return "Local Workspace • Remote Broker Lost"
        }
        if remoteSessionStore.runtimeState == .failed, remoteSessionStore.hasBrokerSession {
            return "Local Workspace • Remote Broker Failed"
        }
        if remoteSessionStore.runtimeState == .failed {
            return "Local Workspace • Remote Failed"
        }
        if remoteSessionStore.isBrokerClientAttached {
            return "Local Workspace • Remote Broker Attached"
        }
        if remoteSessionStore.hasBrokerSession {
            return "Local Workspace • Remote Broker Active"
        }
        if remoteSessionStore.isRemotePreviewConnecting {
            return "Local Workspace • Remote Connecting"
        }
        if remoteSessionStore.isRemotePreviewConnected {
            return "Local Workspace • Remote Session Active"
        }
        if remoteSessionStore.isRemotePreviewReady {
            return "Local Workspace • Remote Selected"
        }
        return remotePreparedTarget.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
            ? "Local Workspace • Remote Enabled"
            : "Local Workspace • Remote Ready"
    }

    private var remoteSessionBadgeForegroundColor: Color {
        remoteSessionStore.runtimeState == .failed ? .red : .secondary
    }

    private var remoteSessionBadgeBackgroundColor: Color {
        remoteSessionStore.runtimeState == .failed
            ? Color.red.opacity(0.16)
            : Color.secondary.opacity(0.16)
    }

    private var remoteSessionBadgeAccessibilityValue: String {
        if remoteSessionStore.runtimeState == .failed, remoteSessionStore.isBrokerClientAttached {
            return "Local workspace lost its attached remote broker session. Reattach from Settings using a fresh code."
        }
        if remoteSessionStore.runtimeState == .failed, remoteSessionStore.hasBrokerSession {
            return "Local workspace lost the active macOS remote broker session. Restart the Mac session before attaching again."
        }
        if remoteSessionStore.runtimeState == .failed {
            return "Local workspace remote session failed."
        }
        return remoteSessionStore.isBrokerClientAttached
            ? "Local workspace attached to a remote broker for read-only browsing"
            : (
            remoteSessionStore.hasBrokerSession
            ? "Local workspace with an active remote broker session on macOS"
            : (
            remoteSessionStore.isRemotePreviewConnecting
            ? "Local workspace with a remote session connection in progress"
            : (
                remoteSessionStore.isRemotePreviewConnected
                ? "Local workspace with an active remote session connection"
                : (
                    remoteSessionStore.isRemotePreviewReady
                    ? "Local workspace with a selected remote preview target"
                    : (
                        remotePreparedTarget.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
                        ? "Local workspace with remote preview enabled"
                        : "Local workspace with a prepared remote target"
                    )
                )
            )
            )
        )
    }

    private var windowSubtitleText: String {
        [largeFileStatusBadgeText, remoteSessionStatusBadgeText]
            .filter { !$0.isEmpty }
            .joined(separator: " • ")
    }

    private var sidebarTOCContent: String {
        if effectiveLargeFileModeEnabled || currentDocumentUTF16Length >= 400_000 {
            return ""
        }
        return currentContent
    }

    var brainDumpLayoutEnabled: Bool {
#if os(macOS)
        return viewModel.isBrainDumpMode
#else
        return false
#endif
    }


    func toggleAutoCompletion() {
        let willEnable = !isAutoCompletionEnabled
        if willEnable && viewModel.isBrainDumpMode {
            viewModel.isBrainDumpMode = false
            UserDefaults.standard.set(false, forKey: "BrainDumpModeEnabled")
        }
        isAutoCompletionEnabled.toggle()
        syncAppleCompletionAvailability()
        if willEnable {
            maybePromptForLanguageSetup()
        }
    }

    private func maybePromptForLanguageSetup() {
        guard currentLanguage == "plain" else { return }
        languagePromptSelection = currentLanguage == "plain" ? "plain" : currentLanguage
        languagePromptInsertTemplate = false
        showLanguageSetupPrompt = true
    }

    private func syncAppleCompletionAvailability() {
#if USE_FOUNDATION_MODELS && canImport(FoundationModels)
        // Keep Apple Foundation Models in sync with the completion master toggle.
        AppleFM.isEnabled = isAutoCompletionEnabled
#endif
    }

    private func applyLanguageSelection(language: String, insertTemplate: Bool) {
        let contentIsEmpty = currentContent.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
        if let tab = viewModel.selectedTab {
            viewModel.updateTabLanguage(tabID: tab.id, language: language)
            if insertTemplate, contentIsEmpty, let template = starterTemplate(for: language) {
                viewModel.updateTabContent(tabID: tab.id, content: template)
            }
        } else {
            singleLanguage = language
            if insertTemplate, contentIsEmpty, let template = starterTemplate(for: language) {
                singleContent = template
            }
        }
    }

    private var languageSetupSheet: some View {
        let contentIsEmpty = currentContent.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
        let canInsertTemplate = contentIsEmpty

        return VStack(alignment: .leading, spacing: 16) {
            Text("Choose a language for code completion")
                .font(.headline)
            Text("You can change this later from the Language picker.")
                .font(.subheadline)
                .foregroundColor(.secondary)

            Picker("Language", selection: $languagePromptSelection) {
                ForEach(languageOptions, id: \.self) { lang in
                    Text(languageLabel(for: lang)).tag(lang)
                }
            }
            .labelsHidden()
            .frame(maxWidth: 240)

            if canInsertTemplate {
                Toggle("Insert starter template", isOn: $languagePromptInsertTemplate)
            }

            HStack {
                Button("Use Plain Text") {
                    applyLanguageSelection(language: "plain", insertTemplate: false)
                    showLanguageSetupPrompt = false
                }
                Spacer()
                Button("Use Selected Language") {
                    applyLanguageSelection(language: languagePromptSelection, insertTemplate: languagePromptInsertTemplate)
                    showLanguageSetupPrompt = false
                }
                .keyboardShortcut(.defaultAction)
            }
        }
        .padding(20)
        .frame(minWidth: 340)
    }

    var languageOptions: [String] {
        ["swift", "python", "javascript", "typescript", "php", "java", "kotlin", "go", "ruby", "rust", "cobol", "dotenv", "proto", "graphql", "rst", "nginx", "sql", "html", "expressionengine", "css", "c", "cpp", "csharp", "objective-c", "json", "xml", "yaml", "toml", "csv", "ini", "vim", "log", "ipynb", "markdown", "tex", "bash", "zsh", "powershell", "standard", "plain"]
    }

    func languageLabel(for lang: String) -> String {
        switch lang {
        case "php": return "PHP"
        case "cobol": return "COBOL"
        case "dotenv": return "Dotenv"
        case "proto": return "Proto"
        case "graphql": return "GraphQL"
        case "rst": return "reStructuredText"
        case "nginx": return "Nginx"
        case "objective-c": return "Objective-C"
        case "csharp": return "C#"
        case "c": return "C"
        case "cpp": return "C++"
        case "json": return "JSON"
        case "xml": return "XML"
        case "yaml": return "YAML"
        case "toml": return "TOML"
        case "csv": return "CSV"
        case "ini": return "INI"
        case "sql": return "SQL"
        case "vim": return "Vim"
        case "log": return "Log"
        case "ipynb": return "Jupyter Notebook"
        case "tex": return "TeX"
        case "html": return "HTML"
        case "expressionengine": return "ExpressionEngine"
        case "css": return "CSS"
        case "standard": return "Standard"
        default: return lang.capitalized
        }
    }

    var filteredLanguageOptions: [String] {
        let query = languageSearchQuery.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !query.isEmpty else { return languageOptions }
        let lower = query.lowercased()
        return languageOptions.filter { lang in
            lang.localizedCaseInsensitiveContains(lower) || languageLabel(for: lang).localizedCaseInsensitiveContains(lower)
        }
    }

    func presentLanguageSearchSheet() {
        languageSearchQuery = ""
        showLanguageSearchSheet = true
    }

    private var languageSearchSheet: some View {
        NavigationStack {
            List(filteredLanguageOptions, id: \.self) { lang in
                Button {
                    currentLanguagePickerBinding.wrappedValue = lang
                    showLanguageSearchSheet = false
                } label: {
                    HStack {
                        Text(languageLabel(for: lang))
                            .foregroundStyle(.primary)
                        Spacer(minLength: 8)
                        if currentLanguage == lang {
                            Image(systemName: "checkmark")
                                .foregroundStyle(NeonUIStyle.accentBlue)
                        }
                    }
                    .contentShape(Rectangle())
                }
                .buttonStyle(.plain)
                .accessibilityLabel(languageLabel(for: lang))
            }
            .navigationTitle("Select Language")
#if os(iOS)
            .navigationBarTitleDisplayMode(.inline)
#endif
            .searchable(text: $languageSearchQuery, prompt: "Search language")
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Close") { showLanguageSearchSheet = false }
                }
            }
        }
#if os(iOS)
        .presentationDetents([.medium, .large])
#endif
    }

    private func starterTemplate(for language: String) -> String? {
        if let override = UserDefaults.standard.string(forKey: templateOverrideKey(for: language)),
           !override.isEmpty {
            return override
        }
        switch language {
        case "swift":
            return "import Foundation\n\n// TODO: Add code here\n"
        case "python":
            return "def main():\n    pass\n\n\nif __name__ == \"__main__\":\n    main()\n"
        case "javascript":
            return "\"use strict\";\n\nfunction main() {\n  // TODO: Add code here\n}\n\nmain();\n"
        case "typescript":
            return "function main(): void {\n  // TODO: Add code here\n}\n\nmain();\n"
        case "java":
            return "public class Main {\n    public static void main(String[] args) {\n        // TODO: Add code here\n    }\n}\n"
        case "kotlin":
            return "fun main() {\n    // TODO: Add code here\n}\n"
        case "go":
            return "package main\n\nimport \"fmt\"\n\nfunc main() {\n    fmt.Println(\"Hello\")\n}\n"
        case "ruby":
            return "def main\n  # TODO: Add code here\nend\n\nmain\n"
        case "rust":
            return "fn main() {\n    // TODO: Add code here\n}\n"
        case "php":
            return "<?php\n\n// TODO: Add code here\n"
        case "cobol":
            return "       IDENTIFICATION DIVISION.\n       PROGRAM-ID. MAIN.\n\n       PROCEDURE DIVISION.\n           DISPLAY \"TODO\".\n           STOP RUN.\n"
        case "dotenv":
            return "# TODO=VALUE\n"
        case "proto":
            return "syntax = \"proto3\";\n\npackage example;\n\nmessage Example {\n  string id = 1;\n}\n"
        case "graphql":
            return "type Query {\n  hello: String\n}\n"
        case "rst":
            return "Title\n=====\n\nWrite here.\n"
        case "nginx":
            return "server {\n    listen 80;\n    server_name example.com;\n\n    location / {\n        return 200 \"TODO\";\n    }\n}\n"
        case "c":
            return "#include <stdio.h>\n\nint main(void) {\n    // TODO: Add code here\n    return 0;\n}\n"
        case "cpp":
            return "#include <iostream>\n\nint main() {\n    // TODO: Add code here\n    return 0;\n}\n"
        case "csharp":
            return "using System;\n\npublic class Program {\n    public static void Main(string[] args) {\n        // TODO: Add code here\n    }\n}\n"
        case "objective-c":
            return "#import <Foundation/Foundation.h>\n\nint main(int argc, const char * argv[]) {\n    @autoreleasepool {\n        // TODO: Add code here\n    }\n    return 0;\n}\n"
        case "html":
            return "<!doctype html>\n<html lang=\"en\">\n<head>\n  <meta charset=\"utf-8\" />\n  <meta name=\"viewport\" content=\"width=device-width, initial-scale=1\" />\n  <title>Document</title>\n</head>\n<body>\n\n</body>\n</html>\n"
        case "expressionengine":
            return "{exp:channel:entries channel=\"news\" limit=\"10\"}\n  <article>\n    <h2>{title}</h2>\n    <p>{summary}</p>\n  </article>\n{/exp:channel:entries}\n"
        case "css":
            return "/* TODO: Add styles here */\n\nbody {\n  margin: 0;\n}\n"
        case "sql":
            return "-- TODO: Add queries here\n"
        case "markdown":
            return "# Title\n\nWrite here.\n"
        case "tex":
            return "\\documentclass{article}\n\\usepackage[utf8]{inputenc}\n\n\\begin{document}\n\\section{Title}\n\nTODO\n\n\\end{document}\n"
        case "yaml":
            return "# TODO: Add config here\n"
        case "json":
            return "{\n  \"todo\": true\n}\n"
        case "xml":
            return "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<root>\n  <todo>true</todo>\n</root>\n"
        case "toml":
            return "# TODO = \"value\"\n"
        case "csv":
            return "col1,col2\nvalue1,value2\n"
        case "ini":
            return "[section]\nkey=value\n"
        case "vim":
            return "\" TODO: Add vim config here\n"
        case "log":
            return "INFO: TODO\n"
        case "ipynb":
            return "{\n  \"cells\": [],\n  \"metadata\": {},\n  \"nbformat\": 4,\n  \"nbformat_minor\": 5\n}\n"
        case "bash":
            return "#!/usr/bin/env bash\n\nset -euo pipefail\n\n# TODO: Add script here\n"
        case "zsh":
            return "#!/usr/bin/env zsh\n\nset -euo pipefail\n\n# TODO: Add script here\n"
        case "powershell":
            return "# TODO: Add script here\n"
        case "standard":
            return "// TODO: Add code here\n"
        case "plain":
            return "TODO\n"
        default:
            return "TODO\n"
        }
    }

    private func templateOverrideKey(for language: String) -> String {
        "TemplateOverride_\(language)"
    }

    func insertTemplateForCurrentLanguage() {
        let language = currentLanguage
        guard let template = starterTemplate(for: language) else { return }
        editorExternalMutationRevision &+= 1
        let sourceContent = liveEditorBufferText() ?? currentContentBinding.wrappedValue
        let updated: String
        if sourceContent.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
            updated = template
        } else {
            updated = sourceContent + (sourceContent.hasSuffix("\n") ? "\n" : "\n\n") + template
        }
        currentContentBinding.wrappedValue = updated
    }

    private func detectLanguageWithAppleIntelligence(_ text: String) async -> String {
        // Supported languages in our picker
        let supported = ["swift", "python", "javascript", "typescript", "php", "java", "kotlin", "go", "ruby", "rust", "cobol", "dotenv", "proto", "graphql", "rst", "nginx", "sql", "html", "expressionengine", "css", "c", "cpp", "objective-c", "csharp", "json", "xml", "yaml", "toml", "csv", "ini", "vim", "log", "ipynb", "markdown", "tex", "bash", "zsh", "powershell", "standard", "plain"]

        #if USE_FOUNDATION_MODELS && canImport(FoundationModels)
        // Attempt a lightweight model-based detection via AppleIntelligenceAIClient if available
        do {
            let client = AppleIntelligenceAIClient()
            var response = ""
            for await chunk in client.streamSuggestions(prompt: "Detect the programming or markup language of the following snippet and answer with one of: \(supported.joined(separator: ", ")). If none match, reply with 'swift'.\n\nSnippet:\n\n\(text)\n\nAnswer:") {
                response += chunk
            }
            let detectedRaw = response.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).lowercased()
            if let match = supported.first(where: { detectedRaw.contains($0) }) {
                return match
            }
        }
        #endif

        // Heuristic fallback
        let lower = text.lowercased()
        // Normalize common C# indicators to "csharp" to ensure the picker has a matching tag
        if lower.contains("c#") || lower.contains("c sharp") || lower.range(of: #"\bcs\b"#, options: .regularExpression) != nil || lower.contains(".cs") {
            return "csharp"
        }
        if lower.contains("<?php") || lower.contains("<?=") || lower.contains("$this->") || lower.contains("$_get") || lower.contains("$_post") || lower.contains("$_server") {
            return "php"
        }
        if lower.range(of: #"\{/?exp:[A-Za-z0-9_:-]+[^}]*\}"#, options: .regularExpression) != nil ||
            lower.range(of: #"\{if(?::elseif)?\b[^}]*\}|\{\/if\}|\{:else\}"#, options: .regularExpression) != nil ||
            lower.range(of: #"\{!--[\s\S]*?--\}"#, options: .regularExpression) != nil {
            return "expressionengine"
        }
        if lower.contains("syntax = \"proto") || lower.contains("message ") || (lower.contains("enum ") && lower.contains("rpc ")) {
            return "proto"
        }
        if lower.contains("type query") || lower.contains("schema {") || (lower.contains("interface ") && lower.contains("implements ")) {
            return "graphql"
        }
        if lower.contains("server {") || lower.contains("http {") || lower.contains("location /") {
            return "nginx"
        }
        if lower.contains(".. code-block::") || lower.contains(".. toctree::") || (lower.contains("::") && lower.contains("\n====")) {
            return "rst"
        }
        if lower.contains("\\documentclass")
            || lower.contains("\\usepackage")
            || lower.contains("\\begin{document}")
            || lower.contains("\\end{document}") {
            return "tex"
        }
        if lower.contains("\n") && lower.range(of: #"(?m)^[A-Z_][A-Z0-9_]*=.*$"#, options: .regularExpression) != nil {
            return "dotenv"
        }
        if lower.contains("identification division") || lower.contains("procedure division") || lower.contains("working-storage section") || lower.contains("environment division") {
            return "cobol"
        }
        if text.contains(",") && text.contains("\n") {
            let lines = text.split(separator: "\n", omittingEmptySubsequences: true)
            if lines.count >= 2 {
                let commaCounts = lines.prefix(6).map { line in line.filter { $0 == "," }.count }
                if let firstCount = commaCounts.first, firstCount > 0 && commaCounts.dropFirst().allSatisfy({ $0 == firstCount || abs($0 - firstCount) <= 1 }) {
                    return "csv"
                }
            }
        }
        // C# strong heuristic
        if lower.contains("using system") || lower.contains("namespace ") || lower.contains("public class") || lower.contains("public static void main") || lower.contains("static void main") || lower.contains("console.writeline") || lower.contains("console.readline") || lower.contains("class program") || lower.contains("get; set;") || lower.contains("list<") || lower.contains("dictionary<") || lower.contains("ienumerable<") || lower.range(of: #"\[[A-Za-z_][A-Za-z0-9_]*\]"#, options: .regularExpression) != nil {
            return "csharp"
        }
        if lower.contains("import swift") || lower.contains("struct ") || lower.contains("func ") {
            return "swift"
        }
        if lower.contains("def ") || (lower.contains("class ") && lower.contains(":")) {
            return "python"
        }
        if lower.contains("function ") || lower.contains("const ") || lower.contains("let ") || lower.contains("=>") {
            return "javascript"
        }
        // XML
        if lower.contains("<?xml") || (lower.contains("</") && lower.contains(">")) {
            return "xml"
        }
        // YAML
        if lower.contains(": ") && (lower.contains("- ") || lower.contains("\n  ")) && !lower.contains(";") {
            return "yaml"
        }
        // TOML / INI
        if lower.range(of: #"^\[[^\]]+\]"#, options: [.regularExpression, .anchored]) != nil || (lower.contains("=") && lower.contains("\n[")) {
            return lower.contains("toml") ? "toml" : "ini"
        }
        // SQL
        if lower.range(of: #"\b(select|insert|update|delete|create\s+table|from|where|join)\b"#, options: .regularExpression) != nil {
            return "sql"
        }
        // Go
        if lower.contains("package ") && lower.contains("func ") {
            return "go"
        }
        // Java
        if lower.contains("public class") || lower.contains("public static void main") {
            return "java"
        }
        // Kotlin
        if (lower.contains("fun ") || lower.contains("val ")) || (lower.contains("var ") && lower.contains(":")) {
            return "kotlin"
        }
        // TypeScript
        if lower.contains("interface ") || (lower.contains("type ") && lower.contains(":")) || lower.contains(": string") {
            return "typescript"
        }
        // Ruby
        if lower.contains("def ") || (lower.contains("end") && lower.contains("class ")) {
            return "ruby"
        }
        // Rust
        if lower.contains("fn ") || lower.contains("let mut ") || lower.contains("pub struct") {
            return "rust"
        }
        // Objective-C
        if lower.contains("@interface") || lower.contains("@implementation") || lower.contains("#import ") {
            return "objective-c"
        }
        // INI
        if lower.range(of: #"^;.*$"#, options: .regularExpression) != nil || lower.range(of: #"^\w+\s*=\s*.*$"#, options: .regularExpression) != nil {
            return "ini"
        }
        if lower.contains("<html") || lower.contains("<div") || lower.contains("</") {
            return "html"
        }
        // Stricter C-family detection to avoid misclassifying C#
        if lower.contains("#include") || lower.range(of: #"^\s*(int|void)\s+main\s*\("#, options: .regularExpression) != nil {
            return "cpp"
        }
        if lower.contains("class ") && (lower.contains("::") || lower.contains("template<")) {
            return "cpp"
        }
        if lower.contains(";") && lower.contains(":") && lower.contains("{") && lower.contains("}") && lower.contains("color:") {
            return "css"
        }
        // Shell detection (bash/zsh)
        if lower.contains("#!/bin/bash") || lower.contains("#!/usr/bin/env bash") || lower.contains("declare -a") || lower.contains("[[ ") || lower.contains(" ]] ") || lower.contains("$(") {
            return "bash"
        }
        if lower.contains("#!/bin/zsh") || lower.contains("#!/usr/bin/env zsh") || lower.contains("typeset ") || lower.contains("autoload -Uz") || lower.contains("setopt ") {
            return "zsh"
        }
        // Generic POSIX sh fallback
        if lower.contains("#!/bin/sh") || lower.contains("#!/usr/bin/env sh") || lower.contains(" fi") || lower.contains(" do") || lower.contains(" done") || lower.contains(" esac") {
            return "bash"
        }
        // PowerShell detection
        if lower.contains("write-host") || lower.contains("param(") || lower.contains("$psversiontable") || lower.range(of: #"\b(Get|Set|New|Remove|Add|Clear|Write)-[A-Za-z]+\b"#, options: .regularExpression) != nil {
            return "powershell"
        }
        return "standard"
    }

    ///MARK: - Main Editor Stack
    @ViewBuilder
    private var projectStructureSidebarPanel: some View {
#if os(macOS)
        projectStructureSidebarBody
            .frame(
            minWidth: clampedProjectSidebarWidth,
            idealWidth: clampedProjectSidebarWidth,
            maxWidth: clampedProjectSidebarWidth
        )
#else
        projectStructureSidebarBody
            .frame(
                minWidth: clampedProjectSidebarWidth,
                idealWidth: clampedProjectSidebarWidth,
                maxWidth: clampedProjectSidebarWidth
            )
            .background(editorSurfaceBackgroundStyle)
#endif
    }

    private var projectSidebarResizeHandle: some View {
        let drag = DragGesture(minimumDistance: 0)
            .onChanged { value in
                let startWidth = projectSidebarResizeStartWidth ?? clampedProjectSidebarWidth
                if projectSidebarResizeStartWidth == nil {
                    projectSidebarResizeStartWidth = startWidth
                }
                let delta = value.translation.width
                let proposed: CGFloat
                switch projectNavigatorPlacement {
                case .leading:
                    proposed = startWidth + delta
                case .trailing:
                    proposed = startWidth - delta
                }
                let clamped = min(max(proposed, minimumProjectSidebarWidth), maximumProjectSidebarWidth)
                projectSidebarWidth = Double(clamped)
            }
            .onEnded { _ in
                projectSidebarResizeStartWidth = nil
            }

        return ZStack {
            // Match the same surface as the editor area so the splitter doesn't look like a foreign strip.
            Rectangle()
                .fill(projectSidebarHandleSurfaceStyle)
            Rectangle()
                .fill(Color.secondary.opacity(0.22))
                .frame(width: 1)
                .frame(maxWidth: .infinity, alignment: projectNavigatorPlacement == .leading ? .leading : .trailing)
        }
        .frame(width: 10)
        .contentShape(Rectangle())
        .gesture(drag)
#if os(macOS)
        .onHover { hovering in
            guard hovering != isProjectSidebarResizeHandleHovered else { return }
            isProjectSidebarResizeHandleHovered = hovering
            if hovering {
                NSCursor.resizeLeftRight.push()
            } else {
                NSCursor.pop()
            }
        }
        .onDisappear {
            if isProjectSidebarResizeHandleHovered {
                isProjectSidebarResizeHandleHovered = false
                NSCursor.pop()
            }
        }
#endif
        .accessibilityElement()
        .accessibilityLabel("Resize Project Sidebar")
        .accessibilityHint("Drag left or right to adjust project sidebar width")
    }

    private var projectSidebarHandleSurfaceStyle: AnyShapeStyle {
        if enableTranslucentWindow {
            return editorSurfaceBackgroundStyle
        }
#if os(iOS)
        return useIOSUnifiedSolidSurfaces
            ? AnyShapeStyle(iOSNonTranslucentSurfaceColor)
            : AnyShapeStyle(Color.clear)
#else
        return AnyShapeStyle(Color.clear)
#endif
    }

#if os(iOS)
    var iOSSurfaceSeparatorFill: Color {
        iOSNonTranslucentSurfaceColor
    }

    var iOSSurfaceSeparatorLine: Color {
        colorScheme == .dark ? Color.white.opacity(0.14) : Color.black.opacity(0.10)
    }

    var iOSPaneDivider: some View {
        ZStack {
            Rectangle()
                .fill(iOSSurfaceSeparatorFill)
            Rectangle()
                .fill(iOSSurfaceSeparatorLine)
                .frame(width: 1)
        }
        .frame(width: 10)
    }

    var iOSHorizontalSurfaceDivider: some View {
        ZStack {
            Rectangle()
                .fill(iOSSurfaceSeparatorFill)
            Rectangle()
                .fill(iOSSurfaceSeparatorLine)
                .frame(height: 1)
        }
        .frame(height: 10)
    }

    var iOSVerticalSurfaceDivider: some View {
        ZStack {
            Rectangle()
                .fill(iOSSurfaceSeparatorFill)
            Rectangle()
                .fill(iOSSurfaceSeparatorLine)
                .frame(width: 1)
        }
        .frame(width: 10, height: 18)
    }
#endif

    private var projectStructureSidebarBody: some View {
        ProjectStructureSidebarView(
            rootFolderURL: projectRootFolderURL,
            nodes: projectTreeNodes,
            selectedFileURL: viewModel.selectedTab?.fileURL,
            showSupportedFilesOnly: showSupportedProjectFilesOnly,
            translucentBackgroundEnabled: enableTranslucentWindow,
            boundaryEdge: projectNavigatorPlacement == .leading ? .trailing : .leading,
            onOpenFile: { openFileFromToolbar() },
            onOpenFolder: { openProjectFolder() },
            onToggleSupportedFilesOnly: { showSupportedProjectFilesOnly = $0 },
            onOpenProjectFile: { openProjectFile(url: $0) },
            onRefreshTree: { refreshProjectBrowserState() },
            onCreateProjectFile: { startProjectItemCreation(kind: .file, in: $0) },
            onCreateProjectFolder: { startProjectItemCreation(kind: .folder, in: $0) },
            onRenameProjectItem: { startProjectItemRename($0) },
            onDuplicateProjectItem: { duplicateProjectItem($0) },
            onDeleteProjectItem: { requestDeleteProjectItem($0) },
            revealURL: projectTreeRevealURL
        )
    }

    private func handleAppDidBecomeActive() {
        if let selectedID = viewModel.selectedTab?.id {
            viewModel.refreshExternalConflictForTab(tabID: selectedID)
        }
        if projectRootFolderURL != nil {
            refreshProjectBrowserState()
        }
    }

    private func handleAppWillResignActive() {
        persistSessionIfReady()
        persistUnsavedDraftSnapshotIfNeeded()
    }

    private var delimitedModeControl: some View {
        HStack(spacing: 10) {
            Picker("CSV/TSV View Mode", selection: $delimitedViewMode) {
                Text("Table").tag(DelimitedViewMode.table)
                Text("Text").tag(DelimitedViewMode.text)
            }
            .pickerStyle(.segmented)
            .frame(maxWidth: 210)
            .accessibilityLabel("CSV or TSV view mode")
            .accessibilityHint("Switch between table mode and raw text mode")

            if shouldShowDelimitedTable {
                if isBuildingDelimitedTable {
                    ProgressView()
                        .scaleEffect(0.85)
                } else if let snapshot = delimitedTableSnapshot {
                    Text(
                        snapshot.truncated
                        ? "Showing \(snapshot.displayedRows) / \(snapshot.totalRows) rows"
                        : "\(snapshot.totalRows) rows"
                    )
                    .font(.caption)
                    .foregroundStyle(.secondary)
                } else if !delimitedTableStatus.isEmpty {
                    Text(delimitedTableStatus)
                        .font(.caption)
                        .foregroundStyle(.secondary)
                }
            }
            Spacer(minLength: 0)
        }
        .padding(.horizontal, 10)
        .padding(.vertical, 8)
        .background(delimitedHeaderBackgroundColor)
    }

    private var delimitedHeaderBackgroundColor: Color {
#if os(macOS)
        currentEditorTheme(colorScheme: colorScheme).background
#else
        Color(.systemBackground)
#endif
    }

    private var delimitedTableView: some View {
        Group {
            if isBuildingDelimitedTable {
                VStack(spacing: 12) {
                    ProgressView()
                    Text("Building table view…")
                        .font(.footnote)
                        .foregroundStyle(.secondary)
                }
                .frame(maxWidth: .infinity, maxHeight: .infinity)
            } else if let snapshot = delimitedTableSnapshot {
                ScrollView([.horizontal, .vertical]) {
                    LazyVStack(alignment: .leading, spacing: 0, pinnedViews: [.sectionHeaders]) {
                        Section {
                            ForEach(Array(snapshot.rows.enumerated()), id: \.offset) { index, row in
                                delimitedRowView(cells: row, isHeader: false, rowIndex: index)
                            }
                        } header: {
                            delimitedRowView(cells: snapshot.header, isHeader: true, rowIndex: nil)
                        }
                    }
                    .padding(.horizontal, 8)
                    .padding(.vertical, 6)
                }
                .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
            } else {
                Text(delimitedTableStatus.isEmpty ? "No rows found." : delimitedTableStatus)
                    .font(.footnote)
                    .foregroundStyle(.secondary)
                    .frame(maxWidth: .infinity, maxHeight: .infinity)
            }
        }
        .background(
            Group {
                if enableTranslucentWindow {
                    Color.clear.background(editorSurfaceBackgroundStyle)
                } else {
                    #if os(iOS)
                    iOSNonTranslucentSurfaceColor
                    #else
                    Color.clear
                    #endif
                }
            }
        )
        .accessibilityElement(children: .contain)
        .accessibilityLabel("CSV or TSV table")
    }

    private func delimitedRowView(cells: [String], isHeader: Bool, rowIndex: Int?) -> some View {
        HStack(spacing: 0) {
            ForEach(Array(cells.enumerated()), id: \.offset) { _, cell in
                Text(cell)
                    .font(.system(size: 12, weight: isHeader ? .semibold : .regular, design: .monospaced))
                    .lineLimit(1)
                    .truncationMode(.tail)
                    .frame(width: 220, alignment: .leading)
                    .padding(.horizontal, 8)
                    .padding(.vertical, isHeader ? 7 : 6)
                    .overlay(alignment: .trailing) {
                        Rectangle()
                            .fill(Color.secondary.opacity(0.16))
                            .frame(width: 1)
                    }
            }
        }
        .background(
            isHeader
            ? Color.secondary.opacity(0.12)
            : ((rowIndex ?? 0).isMultiple(of: 2) ? Color.secondary.opacity(0.04) : Color.clear)
        )
    }

    private func scheduleDelimitedTableRebuild(for text: String) {
        guard isDelimitedFileLanguage else {
            delimitedParseTask?.cancel()
            isBuildingDelimitedTable = false
            delimitedTableSnapshot = nil
            delimitedTableStatus = ""
            return
        }
        guard shouldShowDelimitedTable else { return }

        delimitedParseTask?.cancel()
        isBuildingDelimitedTable = true
        delimitedTableStatus = "Parsing…"
        let separator = delimitedSeparator
        delimitedParseTask = Task {
            let source = text
            let parsed = await Task.detached(priority: .utility) {
                Self.buildDelimitedTableSnapshot(from: source, separator: separator, maxRows: 5000, maxColumns: 60)
            }.value
            guard !Task.isCancelled else { return }
            isBuildingDelimitedTable = false
            switch parsed {
            case .success(let snapshot):
                delimitedTableSnapshot = snapshot
                delimitedTableStatus = ""
            case .failure(let error):
                delimitedTableSnapshot = nil
                delimitedTableStatus = error.localizedDescription
            }
        }
    }

    private nonisolated static func buildDelimitedTableSnapshot(
        from text: String,
        separator: Character,
        maxRows: Int,
        maxColumns: Int
    ) -> Result<DelimitedTableSnapshot, DelimitedTableParseError> {
        guard !text.isEmpty else { return .failure(DelimitedTableParseError(message: "No data in file.")) }
        var rows: [[String]] = []
        rows.reserveCapacity(min(maxRows, 512))
        var totalRows = 0
        for line in text.split(separator: "\n", omittingEmptySubsequences: false) {
            totalRows += 1
            if rows.count < maxRows {
                rows.append(parseDelimitedLine(String(line), separator: separator, maxColumns: maxColumns))
            }
        }
        guard !rows.isEmpty else { return .failure(DelimitedTableParseError(message: "No rows found.")) }
        let rawHeader = rows.removeFirst()
        let visibleColumns = max(rawHeader.count, rows.first?.count ?? 0)
        let header: [String] = {
            if rawHeader.isEmpty {
                return (0..<visibleColumns).map { "Column \($0 + 1)" }
            }
            return rawHeader.enumerated().map { idx, value in
                let trimmed = value.trimmingCharacters(in: .whitespacesAndNewlines)
                return trimmed.isEmpty ? "Column \(idx + 1)" : trimmed
            }
        }()
        let normalizedRows = rows.map { row in
            if row.count >= visibleColumns { return row }
            return row + Array(repeating: "", count: visibleColumns - row.count)
        }
        return .success(
            DelimitedTableSnapshot(
                header: header,
                rows: normalizedRows,
                totalRows: totalRows,
                displayedRows: rows.count,
                truncated: totalRows > maxRows
            )
        )
    }

    private nonisolated static func parseDelimitedLine(
        _ line: String,
        separator: Character,
        maxColumns: Int
    ) -> [String] {
        if line.isEmpty { return [""] }
        var result: [String] = []
        result.reserveCapacity(min(32, maxColumns))
        var field = ""
        var inQuotes = false
        var iterator = line.makeIterator()
        while let char = iterator.next() {
            if char == "\"" {
                if inQuotes {
                    if let next = iterator.next() {
                        if next == "\"" {
                            field.append("\"")
                        } else {
                            inQuotes = false
                            if next == separator {
                                result.append(field)
                                field.removeAll(keepingCapacity: true)
                            } else {
                                field.append(next)
                            }
                        }
                    } else {
                        inQuotes = false
                    }
                } else {
                    inQuotes = true
                }
                continue
            }
            if char == separator && !inQuotes {
                result.append(field)
                field.removeAll(keepingCapacity: true)
                if result.count >= maxColumns {
                    return result
                }
                continue
            }
            field.append(char)
        }
        result.append(field)
        if result.count > maxColumns {
            return Array(result.prefix(maxColumns))
        }
        return result
    }

    var editorView: some View {
        @Bindable var bindableViewModel = viewModel
        let shouldThrottleFeatures = shouldThrottleHeavyEditorFeatures()
        let effectiveHighlightCurrentLine = highlightCurrentLine && !shouldThrottleFeatures
        let effectiveBracketHighlight = highlightMatchingBrackets && !shouldThrottleFeatures
        let effectiveScopeGuides = showScopeGuides && !shouldThrottleFeatures
        let effectiveScopeBackground = highlightScopeBackground && !shouldThrottleFeatures
        let content = HStack(spacing: 0) {
            if showProjectStructureSidebar && projectNavigatorPlacement == .leading && !brainDumpLayoutEnabled {
                projectStructureSidebarPanel
                projectSidebarResizeHandle
            }

            VStack(spacing: 0) {
                if !useIPhoneUnifiedTopHost && !brainDumpLayoutEnabled {
                    tabBarView
                }
#if os(macOS)
                if showBracketHelperBarMac {
                    bracketHelperBar
                }
#endif

                if isDelimitedFileLanguage && !brainDumpLayoutEnabled {
                    delimitedModeControl
                }

                Group {
                    if shouldShowDelimitedTable && !brainDumpLayoutEnabled {
                        delimitedTableView
                    } else if shouldUseDeferredLargeFileOpenMode,
                              viewModel.selectedTab?.isLoadingContent == true,
                              (viewModel.selectedTab?.isLargeFileCandidate == true ||
                               currentDocumentUTF16Length >= 300_000 ||
                               largeFileModeEnabled) {
                        largeFileLoadingPlaceholder
                    } else {
                        // Single editor (no TabView)
                        CustomTextEditor(
                            text: currentContentBinding,
                            documentID: viewModel.selectedTabID,
                            externalEditRevision: editorExternalMutationRevision,
                            language: currentLanguage,
                            colorScheme: colorScheme,
                            fontSize: editorFontSize,
                            isLineWrapEnabled: $bindableViewModel.isLineWrapEnabled,
                            isLargeFileMode: effectiveLargeFileModeEnabled,
                            translucentBackgroundEnabled: enableTranslucentWindow,
                            showKeyboardAccessoryBar: {
#if os(iOS)
                                showKeyboardAccessoryBarIOS
#else
                                true
#endif
                            }(),
                            showLineNumbers: showLineNumbers,
                            showInvisibleCharacters: showInvisibleCharacters,
                            highlightCurrentLine: effectiveHighlightCurrentLine,
                            highlightMatchingBrackets: effectiveBracketHighlight,
                            showScopeGuides: effectiveScopeGuides,
                            highlightScopeBackground: effectiveScopeBackground,
                            indentStyle: indentStyle,
                            indentWidth: effectiveIndentWidth,
                            autoIndentEnabled: autoIndentEnabled,
                            autoCloseBracketsEnabled: autoCloseBracketsEnabled,
                            highlightRefreshToken: highlightRefreshToken,
                            isTabLoadingContent: viewModel.selectedTab?.isLoadingContent ?? false,
                            isReadOnly: isSelectedTabReadOnlyPreview,
                            onTextMutation: { mutation in
                                viewModel.applyTabContentEdit(
                                    tabID: mutation.documentID,
                                    range: mutation.range,
                                    replacement: mutation.replacement
                                )
                            }
                        )
                        .id(currentLanguage)
                        .overlay {
                            if shouldShowStartupOverlay {
                                startupOverlay
                            }
                        }
                    }
                }
                .frame(maxWidth: brainDumpLayoutEnabled ? 920 : .infinity)
                .frame(maxHeight: .infinity)
                .padding(.horizontal, brainDumpLayoutEnabled ? 24 : 0)
                .padding(.vertical, brainDumpLayoutEnabled ? 40 : 0)
                .background(
                    Group {
                        if enableTranslucentWindow {
                            Color.clear.background(editorSurfaceBackgroundStyle)
                        } else {
                            #if os(iOS)
                            iOSNonTranslucentSurfaceColor
                            #else
                            Color.clear
                            #endif
                        }
                    }
                )
                .overlay(alignment: .topTrailing) {
                    if effectiveLargeFileModeEnabled && !brainDumpLayoutEnabled {
                        largeFileSessionBadge
                            .padding(.top, 10)
                            .padding(.trailing, 12)
                            .zIndex(5)
                    }
                }

                if !brainDumpLayoutEnabled {
#if os(macOS)
                    wordCountView
#endif
                }
            }
            .frame(
                maxWidth: .infinity,
                maxHeight: .infinity,
                alignment: brainDumpLayoutEnabled ? .top : .topLeading
            )

            if canShowMarkdownPreviewSplitPane && showMarkdownPreviewPane && currentLanguage == "markdown" && !brainDumpLayoutEnabled {
#if os(iOS)
                iOSPaneDivider
#else
                Divider()
#endif
                markdownPreviewPane
                    .frame(minWidth: 280, idealWidth: 420, maxWidth: 680, maxHeight: .infinity)
            }

            if showProjectStructureSidebar && projectNavigatorPlacement == .trailing && !brainDumpLayoutEnabled {
                projectSidebarResizeHandle
                projectStructureSidebarPanel
            }
        }
        .background(
            Group {
                if brainDumpLayoutEnabled && enableTranslucentWindow {
                    Color.clear.background(editorSurfaceBackgroundStyle)
                } else {
                    #if os(iOS)
                    Color.clear.background(editorSurfaceBackgroundStyle)
                    #else
                    Color.clear
                    #endif
                }
            }
        )
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)

#if os(iOS)
        let contentWithTopChrome = useIPhoneUnifiedTopHost
            ? AnyView(
                content.safeAreaInset(edge: .top, spacing: 0) {
                    iPhoneUnifiedTopChromeHost
                }
            )
            : AnyView(content)
#else
        let contentWithTopChrome = AnyView(content)
#endif

        let withEvents = withTypingEvents(
            withCommandEvents(
                withBaseEditorEvents(contentWithTopChrome)
            )
        )

        return withEvents
        .onAppear {
            if isDelimitedFileLanguage {
                delimitedViewMode = .table
            } else {
                delimitedViewMode = .text
            }
            refreshSecondaryContentViewsIfNeeded()
        }
        .onChange(of: viewModel.tabsObservationToken) { _, _ in
            refreshSecondaryContentViewsIfNeeded()
        }
        .onChange(of: delimitedViewMode) { _, newValue in
            if newValue == .table {
                refreshSecondaryContentViewsIfNeeded()
            } else {
                delimitedParseTask?.cancel()
                isBuildingDelimitedTable = false
            }
        }
        .onChange(of: currentLanguage) { _, _ in
            if isDelimitedFileLanguage {
                if delimitedViewMode == .text {
                    // Keep explicit user choice when already in text mode.
                } else {
                    delimitedViewMode = .table
                }
                if shouldShowDelimitedTable {
                    refreshSecondaryContentViewsIfNeeded()
                }
            } else {
                delimitedViewMode = .text
                delimitedParseTask?.cancel()
                isBuildingDelimitedTable = false
                delimitedTableSnapshot = nil
                delimitedTableStatus = ""
            }
        }
        .onDisappear {
            wordCountTask?.cancel()
            delimitedParseTask?.cancel()
        }
        .onChange(of: enableTranslucentWindow) { _, newValue in
            applyWindowTranslucency(newValue)
            // Force immediate recolor when translucency changes so syntax highlighting stays visible.
            highlightRefreshToken &+= 1
        }
#if os(iOS)
        .onChange(of: showKeyboardAccessoryBarIOS) { _, isVisible in
            NotificationCenter.default.post(
                name: .keyboardAccessoryBarVisibilityChanged,
                object: isVisible
            )
        }
        .onChange(of: horizontalSizeClass) { _, newClass in
            if UIDevice.current.userInterfaceIdiom == .pad && newClass != .regular && showMarkdownPreviewPane {
                showMarkdownPreviewPane = false
            }
        }
        .onChange(of: showSettingsSheet) { _, isPresented in
            if isPresented {
                if previousKeyboardAccessoryVisibility == nil {
                    previousKeyboardAccessoryVisibility = showKeyboardAccessoryBarIOS
                }
                showKeyboardAccessoryBarIOS = false
            } else if let previousKeyboardAccessoryVisibility {
                showKeyboardAccessoryBarIOS = previousKeyboardAccessoryVisibility
                self.previousKeyboardAccessoryVisibility = nil
            }
        }
#endif
#if os(macOS)
        .onChange(of: macTranslucencyModeRaw) { _, _ in
            // Keep all chrome/background surfaces in lockstep when mode changes.
            applyWindowTranslucency(enableTranslucentWindow)
            highlightRefreshToken &+= 1
        }
        .onChange(of: colorScheme) { _, _ in
            applyWindowTranslucency(enableTranslucentWindow)
            highlightRefreshToken &+= 1
        }
#endif
        .toolbar {
            editorToolbarContent
        }
        .overlay(alignment: Alignment.topTrailing) {
            if droppedFileLoadInProgress {
                HStack(spacing: 8) {
                    if droppedFileProgressDeterminate {
                        ProgressView(value: droppedFileLoadProgress)
                            .progressViewStyle(.linear)
                            .frame(width: 120)
                    } else {
                        ProgressView()
                            .frame(width: 16)
                    }
                    Text(droppedFileProgressDeterminate ? "\(droppedFileLoadLabel) \(importProgressPercentText)" : "\(droppedFileLoadLabel) Loading…")
                        .font(.system(size: 11, weight: .medium))
                        .lineLimit(1)
                }
                .padding(.horizontal, 10)
                .padding(.vertical, 7)
                .background(.ultraThinMaterial, in: Capsule(style: .continuous))
                .padding(.top, brainDumpLayoutEnabled ? 12 : 50)
                .padding(.trailing, 12)
            }
        }
#if os(iOS)
        .overlay(alignment: .bottomTrailing) {
            if !brainDumpLayoutEnabled {
                floatingStatusPill
                    .padding(.trailing, 12)
                    .padding(.bottom, 12)
            }
        }
#endif
        .onChange(of: currentLanguage) { _, newLanguage in
            if newLanguage != "markdown", showMarkdownPreviewPane {
                showMarkdownPreviewPane = false
            }
        }
#if os(macOS)
        .toolbarBackground(
            macToolbarBackgroundStyle,
            for: ToolbarPlacement.windowToolbar
        )
        .toolbarBackgroundVisibility(Visibility.visible, for: ToolbarPlacement.windowToolbar)
        .tint(NeonUIStyle.accentBlue)
#else
        .toolbarBackground(
            enableTranslucentWindow
            ? AnyShapeStyle(.ultraThinMaterial)
            : AnyShapeStyle(Color(.systemBackground)),
            for: ToolbarPlacement.navigationBar
        )
#endif
    }

    private var largeFileLoadingPlaceholder: some View {
        VStack(spacing: 14) {
            ProgressView()
                .controlSize(.large)
            Text("Preparing large file")
                .font(.headline)
            Text("Deferred open mode keeps first paint lightweight and installs the document in chunks.")
                .font(.subheadline)
                .foregroundStyle(.secondary)
                .multilineTextAlignment(.center)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .padding(24)
        .accessibilityElement(children: .combine)
        .accessibilityLabel("Preparing large file")
        .accessibilityValue("Deferred open mode is loading the editor content")
    }

#if os(macOS) || os(iOS)
    @ViewBuilder
    private var markdownPreviewPane: some View {
        VStack(alignment: .leading, spacing: 0) {
            MarkdownPreviewWebView(
                html: markdownPreviewHTML(
                    from: currentContent,
                    preferDarkMode: markdownPreviewPreferDarkMode
                )
            )
                .frame(maxWidth: .infinity, maxHeight: .infinity)
                .accessibilityLabel("Markdown Preview Content")
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(editorSurfaceBackgroundStyle)
#if canImport(UIKit)
        .fileExporter(
            isPresented: $showMarkdownPDFExporter,
            document: markdownPDFExportDocument,
            contentType: .pdf,
            defaultFilename: markdownPDFExportFilename
        ) { result in
            if case .failure(let error) = result {
                markdownPDFExportErrorMessage = error.localizedDescription
            }
        }
#endif
    }
#endif

    @ViewBuilder
    private var markdownPreviewHeader: some View {
#if os(iOS)
        if UIDevice.current.userInterfaceIdiom == .phone {
            VStack(spacing: 16) {
                VStack(spacing: 10) {
                    markdownPreviewCombinedPickerCard

                    markdownPreviewPrimaryActionRow
                    .padding(.top, 4)
                }
                .padding(16)
                .background(.thinMaterial, in: RoundedRectangle(cornerRadius: 18, style: .continuous))
            }
            .frame(maxWidth: .infinity)
        } else if UIDevice.current.userInterfaceIdiom == .pad {
            markdownPreviewIPadHeader
        } else {
            markdownPreviewRegularHeader
        }
#else
        markdownPreviewRegularHeader
#endif
    }

    private var markdownPreviewRegularHeader: some View {
        VStack(spacing: 16) {
            Text(NSLocalizedString("Markdown Preview", comment: ""))
                .font(.headline)

            VStack(spacing: 10) {
                markdownPreviewCombinedPickerCard

                markdownPreviewPrimaryActionRow
                    .padding(.top, 2)

                markdownPreviewSecondaryActionRow
                .padding(.top, 2)

                Text(markdownPreviewExportSummaryText)
                    .font(.caption)
                    .foregroundStyle(.secondary)
                    .multilineTextAlignment(.center)
                    .accessibilityLabel(NSLocalizedString("Markdown preview export summary", comment: ""))

                markdownPreviewActionStatusView
            }
#if os(iOS)
            .frame(minWidth: 320, maxWidth: 420)
#else
            .frame(minWidth: 520, idealWidth: 640, maxWidth: 760)
#endif
            .padding(16)
            .background(.thinMaterial, in: RoundedRectangle(cornerRadius: 18, style: .continuous))
        }
        .frame(maxWidth: .infinity, alignment: .center)
    }

    private var markdownPreviewIPadHeader: some View {
        VStack(spacing: 16) {
            Text(NSLocalizedString("Markdown Preview", comment: ""))
                .font(.headline)
                .frame(maxWidth: .infinity, alignment: .center)

            VStack(spacing: 10) {
                markdownPreviewPrimaryActionRow
                    .padding(.top, 2)

                markdownPreviewCombinedPickerCard

                markdownPreviewSecondaryActionRow
                .padding(.top, 2)

                Text(markdownPreviewExportSummaryText)
                    .font(.caption)
                    .foregroundStyle(.secondary)
                    .multilineTextAlignment(.center)
                    .accessibilityLabel(NSLocalizedString("Markdown preview export summary", comment: ""))

                markdownPreviewActionStatusView
            }
            .frame(maxWidth: 460)
            .padding(16)
            .background(.thinMaterial, in: RoundedRectangle(cornerRadius: 18, style: .continuous))
        }
        .frame(maxWidth: .infinity, alignment: .center)
    }

    private var markdownPreviewTemplatePicker: some View {
        Picker(NSLocalizedString("Template", comment: ""), selection: $markdownPreviewTemplateRaw) {
            Text(NSLocalizedString("Default", comment: "")).tag("default")
            Text(NSLocalizedString("Docs", comment: "")).tag("docs")
            Text(NSLocalizedString("Article", comment: "")).tag("article")
            Text(NSLocalizedString("Compact", comment: "")).tag("compact")
            Text(NSLocalizedString("GitHub Docs", comment: "")).tag("github-docs")
            Text(NSLocalizedString("Academic Paper", comment: "")).tag("academic-paper")
            Text(NSLocalizedString("Terminal Notes", comment: "")).tag("terminal-notes")
            Text(NSLocalizedString("Magazine", comment: "")).tag("magazine")
            Text(NSLocalizedString("Minimal Reader", comment: "")).tag("minimal-reader")
            Text(NSLocalizedString("Presentation", comment: "")).tag("presentation")
            Text(NSLocalizedString("Night Contrast", comment: "")).tag("night-contrast")
            Text(NSLocalizedString("Warm Sepia", comment: "")).tag("warm-sepia")
            Text(NSLocalizedString("Dense Compact", comment: "")).tag("dense-compact")
            Text(NSLocalizedString("Developer Spec", comment: "")).tag("developer-spec")
        }
        .labelsHidden()
        .pickerStyle(.menu)
#if os(iOS)
        .frame(maxWidth: .infinity, alignment: .center)
#else
        .frame(minWidth: 120, idealWidth: 190, maxWidth: 220)
#endif
    }

    private var markdownPreviewPDFModePicker: some View {
        Picker(NSLocalizedString("PDF Mode", comment: ""), selection: $markdownPDFExportModeRaw) {
            Text(NSLocalizedString("Paginated Fit", comment: "")).tag(MarkdownPDFExportMode.paginatedFit.rawValue)
            Text(NSLocalizedString("One Page Fit", comment: "")).tag(MarkdownPDFExportMode.onePageFit.rawValue)
        }
        .labelsHidden()
        .pickerStyle(.menu)
#if os(iOS)
        .frame(maxWidth: .infinity, alignment: .center)
#else
        .frame(minWidth: 128, idealWidth: 160, maxWidth: 180)
#endif
    }

    private var markdownPreviewExportButton: some View {
        Button {
            exportMarkdownPreviewPDF()
        } label: {
            Label(NSLocalizedString("Export PDF", comment: ""), systemImage: "square.and.arrow.down")
                .lineLimit(1)
                .fixedSize(horizontal: true, vertical: false)
        }
        .buttonStyle(.borderedProminent)
        .tint(NeonUIStyle.accentBlue)
        .controlSize(.regular)
        .layoutPriority(1)
        .accessibilityLabel(NSLocalizedString("Export Markdown preview as PDF", comment: ""))
    }

    private var markdownPreviewShareButton: some View {
        ShareLink(
            item: markdownPreviewShareHTML,
            preview: SharePreview("\(suggestedMarkdownPreviewBaseName()).html")
        ) {
            Label(NSLocalizedString("Share", comment: ""), systemImage: "square.and.arrow.up")
                .lineLimit(1)
                .fixedSize(horizontal: true, vertical: false)
        }
        .buttonStyle(.bordered)
        .controlSize(.regular)
        .layoutPriority(1)
        .accessibilityLabel(NSLocalizedString("Share Markdown preview HTML", comment: ""))
    }

    private var markdownPreviewCopyHTMLButton: some View {
        Button {
            copyMarkdownPreviewHTML()
        } label: {
            Label(NSLocalizedString("Copy HTML", comment: ""), systemImage: "doc.on.doc")
                .lineLimit(1)
                .fixedSize(horizontal: true, vertical: false)
        }
        .buttonStyle(.bordered)
        .controlSize(.regular)
        .layoutPriority(1)
        .accessibilityLabel(NSLocalizedString("Copy Markdown preview HTML", comment: ""))
    }

    private var markdownPreviewCopyMarkdownButton: some View {
        Button {
            copyMarkdownPreviewMarkdown()
        } label: {
            Label(NSLocalizedString("Copy Markdown", comment: ""), systemImage: "doc.on.clipboard")
                .lineLimit(1)
                .fixedSize(horizontal: true, vertical: false)
        }
        .buttonStyle(.bordered)
        .controlSize(.regular)
        .layoutPriority(1)
        .accessibilityLabel(NSLocalizedString("Copy Markdown source", comment: ""))
    }

    private var markdownPreviewExportSummaryText: String {
        "\(suggestedMarkdownPDFFilename()) • \(suggestedMarkdownPreviewBaseName()).html"
    }

    @ViewBuilder
    private var markdownPreviewActionStatusView: some View {
        if !markdownPreviewActionStatusMessage.isEmpty {
            Text(markdownPreviewActionStatusMessage)
                .font(.caption2.weight(.semibold))
                .foregroundStyle(NeonUIStyle.accentBlue)
                .multilineTextAlignment(.center)
                .accessibilityLabel(NSLocalizedString("Markdown preview action status", comment: ""))
                .accessibilityValue(markdownPreviewActionStatusMessage)
        }
    }

    @ViewBuilder
    private var markdownPreviewMoreActionsMenu: some View {
        Menu {
            Button {
                copyMarkdownPreviewHTML()
            } label: {
                Label(NSLocalizedString("Copy HTML", comment: ""), systemImage: "doc.on.doc")
            }

            Button {
                copyMarkdownPreviewMarkdown()
            } label: {
                Label(NSLocalizedString("Copy Markdown", comment: ""), systemImage: "doc.on.clipboard")
            }
        } label: {
            Label(NSLocalizedString("More", comment: ""), systemImage: "ellipsis.circle")
                .lineLimit(1)
                .fixedSize(horizontal: true, vertical: false)
        }
        .buttonStyle(.bordered)
        .controlSize(.regular)
        .layoutPriority(1)
        .accessibilityLabel(NSLocalizedString("More Markdown preview actions", comment: ""))
    }

    @ViewBuilder
    private var markdownPreviewCombinedPickerCard: some View {
        Group {
            if markdownPreviewUsesStackedIPadPickerLayout {
                HStack(alignment: .top, spacing: markdownPreviewPickerCardSpacing) {
                    markdownPreviewPickerColumn("Template") {
                        markdownPreviewTemplatePicker
                    }

                    markdownPreviewPickerColumn("PDF Mode") {
                        markdownPreviewPDFModePicker
                    }
                }
            } else {
                HStack(alignment: .top, spacing: markdownPreviewPickerCardSpacing) {
                    markdownPreviewPickerColumn("Template") {
                        markdownPreviewTemplatePicker
                    }

                    if markdownPreviewShowsInlineExportControl {
                        markdownPreviewPickerColumn("Export") {
                            markdownPreviewExportButton
                        }
                    }

                    markdownPreviewPickerColumn("PDF Mode") {
                        markdownPreviewPDFModePicker
                    }
                }
            }
        }
        .padding(.horizontal, markdownPreviewPickerCardHorizontalPadding)
        .padding(.vertical, 16)
#if os(iOS)
        .frame(maxWidth: markdownPreviewPickerCardMaxWidth, alignment: .center)
#else
        .frame(minWidth: 460, maxWidth: 560, alignment: .center)
#endif
        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 16, style: .continuous))
        .overlay {
            RoundedRectangle(cornerRadius: 16, style: .continuous)
                .strokeBorder(Color.white.opacity(0.08), lineWidth: 1)
        }
    }

#if os(iOS)
    private var markdownPreviewPickerCardSpacing: CGFloat {
        if UIDevice.current.userInterfaceIdiom == .phone {
            return 18
        }
        if markdownPreviewUsesStackedIPadPickerLayout {
            return 14
        }
        return markdownPreviewShowsInlineExportControl ? 10 : 12
    }

    private var markdownPreviewPickerCardHorizontalPadding: CGFloat {
        if UIDevice.current.userInterfaceIdiom == .phone {
            return 18
        }
        if markdownPreviewUsesStackedIPadPickerLayout {
            return 16
        }
        return markdownPreviewShowsInlineExportControl ? 10 : 12
    }

    private var markdownPreviewPickerCardMaxWidth: CGFloat? {
        UIDevice.current.userInterfaceIdiom == .phone ? nil : 420
    }
#else
    private var markdownPreviewPickerCardSpacing: CGFloat { markdownPreviewShowsInlineExportControl ? 16 : 18 }
    private var markdownPreviewPickerCardHorizontalPadding: CGFloat { markdownPreviewShowsInlineExportControl ? 16 : 18 }
#endif

    private var markdownPreviewShowsInlineExportControl: Bool {
#if os(iOS)
        false
#else
        true
#endif
    }

    private var markdownPreviewUsesStackedIPadPickerLayout: Bool {
#if os(iOS)
        UIDevice.current.userInterfaceIdiom == .pad
#else
        false
#endif
    }

    @ViewBuilder
    private func markdownPreviewPickerColumn<Content: View>(_ title: String, @ViewBuilder content: () -> Content) -> some View {
        VStack(spacing: 10) {
            Text(NSLocalizedString(title, comment: ""))
                .font(.system(size: 13, weight: .semibold))
                .foregroundStyle(.secondary)
                .frame(maxWidth: .infinity, alignment: .center)

            content()
                .frame(maxWidth: .infinity, alignment: .center)
        }
        .frame(maxWidth: .infinity, alignment: .center)
    }

    @ViewBuilder
    private func markdownPreviewActionRow<Content: View>(@ViewBuilder content: () -> Content) -> some View {
        HStack(spacing: 14) {
            content()
        }
        .frame(maxWidth: .infinity, alignment: .center)
    }

    private var markdownPreviewPrimaryActionRow: some View {
        markdownPreviewActionRow {
            if !markdownPreviewShowsInlineExportControl {
                markdownPreviewExportButton
            }
        }
    }

    @ViewBuilder
    private var markdownPreviewSecondaryActionRow: some View {
#if os(iOS)
        if UIDevice.current.userInterfaceIdiom == .phone {
            EmptyView()
        } else {
            markdownPreviewActionRow {
                markdownPreviewSecondaryButtons
            }
        }
#else
        markdownPreviewActionRow {
            markdownPreviewSecondaryButtons
        }
#endif
    }

#if os(macOS)
    @ViewBuilder
    private var markdownPreviewSecondaryButtons: some View {
        HStack(spacing: 20) {
            markdownPreviewShareButton
                .frame(maxWidth: .infinity, alignment: .trailing)

            markdownPreviewCopyHTMLButton
                .frame(maxWidth: .infinity, alignment: .center)

            markdownPreviewCopyMarkdownButton
                .frame(maxWidth: .infinity, alignment: .leading)
        }
        .frame(minWidth: 520, idealWidth: 620, maxWidth: 680)
    }
#else
    @ViewBuilder
    private var markdownPreviewSecondaryButtons: some View {
        if UIDevice.current.userInterfaceIdiom == .pad {
            ViewThatFits(in: .horizontal) {
                HStack(spacing: 10) {
                    markdownPreviewShareButton
                    markdownPreviewMoreActionsMenu
                }

                VStack(spacing: 10) {
                    markdownPreviewShareButton
                    markdownPreviewMoreActionsMenu
                }
            }
        } else {
            HStack(spacing: 10) {
                markdownPreviewShareButton
                markdownPreviewMoreActionsMenu
            }
        }
    }
#endif
		
#if os(iOS)
    @ViewBuilder
    private var iPhoneUnifiedTopChromeHost: some View {
        VStack(spacing: 0) {
            iPhoneUnifiedToolbarRow
                .padding(.horizontal, 8)
                .padding(.vertical, 6)
            tabBarView
        }
        .background(
            enableTranslucentWindow
            ? AnyShapeStyle(.ultraThinMaterial)
            : AnyShapeStyle(iOSNonTranslucentSurfaceColor)
        )
    }

    private var floatingStatusPillText: String {
        let base = effectiveLargeFileModeEnabled
            ? "\(caretStatus) • Lines: \(statusLineCount)\(vimStatusSuffix)"
            : "\(caretStatus) • Lines: \(statusLineCount) • Words: \(statusWordCount)\(vimStatusSuffix)"
        let suffixes = [largeFileStatusBadgeText, remoteSessionStatusBadgeText].filter { !$0.isEmpty }
        if suffixes.isEmpty {
            return base
        }
        return "\(base) • \(suffixes.joined(separator: " • "))"
    }

    private var floatingStatusPill: some View {
        GlassSurface(
            enabled: shouldUseLiquidGlass,
            material: primaryGlassMaterial,
            fallbackColor: toolbarFallbackColor,
            shape: .capsule,
            chromeStyle: .single
        ) {
            Text(floatingStatusPillText)
                .font(.system(size: 12, weight: .medium, design: .monospaced))
                .lineLimit(1)
                .minimumScaleFactor(0.85)
                .foregroundStyle(iOSToolbarForegroundColor)
                .padding(.horizontal, 12)
                .padding(.vertical, 8)
        }
        .accessibilityLabel("Editor status")
        .accessibilityValue(floatingStatusPillText)
    }

    private var iOSToolbarForegroundColor: Color {
        if toolbarIconsBlueIOS {
            return NeonUIStyle.accentBlue
        }
        return colorScheme == .dark ? Color.white.opacity(0.95) : Color.primary.opacity(0.92)
    }
#endif

    // Status line: caret location + live word count from the view model.
    @ViewBuilder
    var wordCountView: some View {
        HStack(spacing: 10) {
            if droppedFileLoadInProgress {
                HStack(spacing: 8) {
                    if droppedFileProgressDeterminate {
                        ProgressView(value: droppedFileLoadProgress)
                            .progressViewStyle(.linear)
                            .frame(width: 130)
                    } else {
                        ProgressView()
                            .frame(width: 18)
                    }
                    Text(droppedFileProgressDeterminate ? "\(droppedFileLoadLabel) \(importProgressPercentText)" : "\(droppedFileLoadLabel) Loading…")
                        .font(.system(size: 11))
                        .foregroundColor(.secondary)
                        .lineLimit(1)
                }
                .padding(.leading, 12)
            }

            if effectiveLargeFileModeEnabled {
                largeFileStatusBadge
                Picker("Large file open mode", selection: $largeFileOpenModeRaw) {
                    Text("Standard").tag("standard")
                    Text("Deferred").tag("deferred")
                    Text("Plain Text").tag("plainText")
                }
                .pickerStyle(.segmented)
                .labelsHidden()
                .frame(width: 280)
                .fixedSize(horizontal: false, vertical: true)
                .controlSize(.small)
                .accessibilityLabel("Large file open mode")
                .accessibilityHint("Choose how large files are opened and rendered")
            }
            if !remoteSessionStatusBadgeText.isEmpty {
                remoteSessionBadge
            }
            if !selectedRemoteDocumentBadgeText.isEmpty {
                selectedRemoteDocumentBadge
            }
            Spacer()
            Text(effectiveLargeFileModeEnabled
                 ? "\(caretStatus) • Lines: \(statusLineCount)\(vimStatusSuffix)"
                 : "\(caretStatus) • Lines: \(statusLineCount) • Words: \(statusWordCount)\(vimStatusSuffix)")
                .font(.system(size: 12))
                .foregroundColor(.secondary)
                .padding(.bottom, 8)
                .padding(.trailing, 16)
        }
        .background(editorSurfaceBackgroundStyle)
    }

    private var largeFileStatusBadge: some View {
        Text(largeFileStatusBadgeText)
            .font(.system(size: 11, weight: .semibold))
            .foregroundColor(.secondary)
            .padding(.horizontal, 8)
            .padding(.vertical, 3)
            .background(
                Capsule(style: .continuous)
                    .fill(Color.secondary.opacity(0.16))
            )
            .accessibilityLabel("Large file mode")
            .accessibilityValue(currentLargeFileOpenModeLabel)
    }

    private var remoteSessionBadge: some View {
        Text(remoteSessionStatusBadgeText)
            .font(.system(size: 11, weight: .semibold))
            .foregroundColor(remoteSessionBadgeForegroundColor)
            .padding(.horizontal, 8)
            .padding(.vertical, 3)
            .background(
                Capsule(style: .continuous)
                    .fill(remoteSessionBadgeBackgroundColor)
            )
            .accessibilityLabel("Remote session status")
            .accessibilityValue(remoteSessionBadgeAccessibilityValue)
    }

    private var selectedRemoteDocumentBadgeText: String {
        guard let tab = viewModel.selectedTab, tab.isRemoteDocument else { return "" }
        return tab.isReadOnlyPreview ? "Remote Document • Read-Only" : "Remote Document • Editable"
    }

    private var selectedRemoteDocumentBadge: some View {
        Text(selectedRemoteDocumentBadgeText)
            .font(.system(size: 11, weight: .semibold))
            .foregroundColor(.secondary)
            .padding(.horizontal, 8)
            .padding(.vertical, 3)
            .background(
                Capsule(style: .continuous)
                    .fill(Color.secondary.opacity(0.16))
            )
            .accessibilityLabel("Selected document status")
            .accessibilityValue(selectedRemoteDocumentBadgeText)
    }

    private var largeFileSessionBadge: some View {
        Menu {
            largeFileOpenModeMenuContent
        } label: {
            HStack(spacing: 8) {
                Image(systemName: "bolt.horizontal.circle.fill")
                    .font(.system(size: 12, weight: .semibold))
                    .foregroundStyle(NeonUIStyle.accentBlue)
                Text(largeFileStatusBadgeText)
                    .font(.system(size: 11, weight: .semibold))
                    .foregroundStyle(.primary)
                    .lineLimit(1)
                Image(systemName: "chevron.down")
                    .font(.system(size: 10, weight: .semibold))
                    .foregroundStyle(.secondary)
            }
            .padding(.horizontal, 10)
            .padding(.vertical, 7)
            .background(.ultraThinMaterial, in: Capsule(style: .continuous))
        }
        .menuStyle(.borderlessButton)
        .accessibilityLabel("Large file session")
        .accessibilityValue(currentLargeFileOpenModeLabel)
        .accessibilityHint("Open large file mode options")
    }

    @ViewBuilder
    private var largeFileOpenModeMenuContent: some View {
        Button {
            largeFileOpenModeRaw = "standard"
        } label: {
            largeFileOpenModeMenuLabel(title: "Standard", isSelected: largeFileOpenModeRaw == "standard")
        }
        Button {
            largeFileOpenModeRaw = "deferred"
        } label: {
            largeFileOpenModeMenuLabel(title: "Deferred", isSelected: largeFileOpenModeRaw == "deferred")
        }
        Button {
            largeFileOpenModeRaw = "plainText"
        } label: {
            largeFileOpenModeMenuLabel(title: "Plain Text", isSelected: largeFileOpenModeRaw == "plainText")
        }
    }

    private func largeFileOpenModeMenuLabel(title: String, isSelected: Bool) -> some View {
        HStack {
            Text(title)
            Spacer(minLength: 10)
            if isSelected {
                Image(systemName: "checkmark")
            }
        }
    }

    @ViewBuilder
    private func tabRemoteBadge(for tab: TabData) -> some View {
        if tab.isRemoteDocument {
            Text("Remote")
                .font(.system(size: 9, weight: .semibold))
                .foregroundStyle(viewModel.selectedTabID == tab.id ? Color.accentColor : Color.secondary)
                .padding(.horizontal, 5)
                .padding(.vertical, 2)
                .background(
                    Capsule(style: .continuous)
                        .fill(Color.accentColor.opacity(viewModel.selectedTabID == tab.id ? 0.16 : 0.10))
                )
        }
    }

    private func tabAccessibilityLabel(for tab: TabData) -> String {
        var parts: [String] = [tab.name]
        if tab.isRemoteDocument {
            parts.append(tab.isReadOnlyPreview ? "remote read only document" : "remote editable document")
        } else {
            parts.append("local document")
        }
        if tab.isDirty {
            parts.append("unsaved changes")
        }
        return parts.joined(separator: ", ")
    }

    @ViewBuilder
    var tabBarView: some View {
        VStack(spacing: 0) {
            ScrollView(.horizontal, showsIndicators: false) {
                HStack(spacing: 6) {
                    if viewModel.tabs.isEmpty {
                        Button {
                            viewModel.addNewTab()
                        } label: {
                            HStack(spacing: 6) {
                                Text("Untitled 1")
                                    .lineLimit(1)
                                    .font(.system(size: 12, weight: .semibold))
                                Image(systemName: "plus")
                                    .font(.system(size: 10, weight: .bold))
                                    .foregroundStyle(NeonUIStyle.accentBlue)
                            }
                            .padding(.horizontal, 10)
                            .padding(.vertical, 6)
                            .background(
                                RoundedRectangle(cornerRadius: 8, style: .continuous)
                                    .fill(Color.accentColor.opacity(0.18))
                            )
                        }
                        .buttonStyle(.plain)
                    } else {
                        ForEach(viewModel.tabs) { tab in
                            HStack(spacing: 8) {
                                Button {
                                    viewModel.selectTab(id: tab.id)
                                } label: {
                                    HStack(spacing: 6) {
                                        tabRemoteBadge(for: tab)
                                        Text(tab.name + (tab.isDirty ? " •" : ""))
                                            .lineLimit(1)
                                            .font(.system(size: 12, weight: viewModel.selectedTabID == tab.id ? .semibold : .regular))
                                        if tab.isReadOnlyPreview {
                                            Image(systemName: "lock.fill")
                                                .font(.system(size: 9, weight: .semibold))
                                                .foregroundStyle(.secondary)
                                        }
                                    }
                                    .padding(.leading, 10)
                                    .padding(.vertical, 6)
                                }
                                .buttonStyle(.plain)
                                .accessibilityLabel(tabAccessibilityLabel(for: tab))
                                .accessibilityHint("Selects this editor tab.")
#if os(macOS)
                                .simultaneousGesture(
                                    TapGesture(count: 2)
                                        .onEnded { requestCloseTab(tab) }
                                )
#endif

                                Button {
                                    requestCloseTab(tab)
                                } label: {
                                    Image(systemName: "xmark")
                                        .font(.system(size: 10, weight: .bold))
                                        .padding(.trailing, 10)
                                }
                                .buttonStyle(.plain)
                                .contentShape(Rectangle())
                                .help("Close \(tab.name)")
                            }
                            .background(
                                RoundedRectangle(cornerRadius: 8, style: .continuous)
                                    .fill(viewModel.selectedTabID == tab.id ? Color.accentColor.opacity(0.18) : Color.secondary.opacity(0.10))
                            )
                        }
                    }
                }
                .padding(.leading, tabBarLeadingPadding)
                .padding(.trailing, 10)
                .padding(.vertical, 6)
            }
#if os(iOS)
            iOSHorizontalSurfaceDivider.opacity(0.7)
#else
            Divider().opacity(0.45)
#endif
        }
        .frame(minHeight: 42, maxHeight: 42, alignment: .center)
#if os(macOS)
        .background(editorSurfaceBackgroundStyle)
#else
        .background(
            enableTranslucentWindow
            ? AnyShapeStyle(.ultraThinMaterial)
            : (useIOSUnifiedSolidSurfaces ? AnyShapeStyle(iOSNonTranslucentSurfaceColor) : AnyShapeStyle(Color(.systemBackground)))
        )
        .contentShape(Rectangle())
        .zIndex(10)
#endif
    }

    private var vimStatusSuffix: String {
#if os(macOS)
        guard vimModeEnabled else { return " • Vim: OFF" }
        return vimInsertMode ? " • Vim: INSERT" : " • Vim: NORMAL"
#else
        guard UIDevice.current.userInterfaceIdiom == .pad else { return "" }
        guard vimModeEnabled else { return " • Vim: OFF" }
        return vimInsertMode ? " • Vim: INSERT" : " • Vim: NORMAL"
#endif
    }

    private var importProgressPercentText: String {
        let clamped = min(max(droppedFileLoadProgress, 0), 1)
        if clamped > 0, clamped < 0.01 { return "1%" }
        return "\(Int(clamped * 100))%"
    }

    private var quickSwitcherItems: [QuickFileSwitcherPanel.Item] {
        _ = recentFilesRefreshToken
        var items: [QuickFileSwitcherPanel.Item] = []
        let fileURLSet = Set(viewModel.tabs.compactMap { $0.fileURL?.standardizedFileURL.path })
        let commandItems: [QuickFileSwitcherPanel.Item] = [
            .init(id: "cmd:new_tab", title: "New Tab", subtitle: "Create a new empty tab", isPinned: false, canTogglePin: false),
            .init(id: "cmd:open_file", title: "Open File", subtitle: "Open files from disk", isPinned: false, canTogglePin: false),
            .init(id: "cmd:save_file", title: "Save", subtitle: "Save current tab", isPinned: false, canTogglePin: false),
            .init(id: "cmd:save_as", title: "Save As", subtitle: "Save current tab to a new file", isPinned: false, canTogglePin: false),
            .init(id: "cmd:find_replace", title: "Find and Replace", subtitle: "Search and replace in current document", isPinned: false, canTogglePin: false),
            .init(id: "cmd:find_in_files", title: "Find in Files", subtitle: "Search across project files", isPinned: false, canTogglePin: false),
            .init(id: "cmd:toggle_sidebar", title: "Toggle Sidebar", subtitle: "Show or hide the outline sidebar", isPinned: false, canTogglePin: false)
        ]
        items.append(contentsOf: commandItems)

        for tab in viewModel.tabs {
            let subtitle = tab.fileURL?.path ?? "Open tab"
            items.append(
                QuickFileSwitcherPanel.Item(
                    id: "tab:\(tab.id.uuidString)",
                    title: tab.name,
                    subtitle: subtitle,
                    isPinned: false,
                    canTogglePin: false
                )
            )
        }

        for recent in RecentFilesStore.items(limit: 12) {
            let standardized = recent.url.standardizedFileURL.path
            if fileURLSet.contains(standardized) { continue }
            items.append(
                QuickFileSwitcherPanel.Item(
                    id: "file:\(standardized)",
                    title: recent.title,
                    subtitle: recent.subtitle,
                    isPinned: recent.isPinned,
                    canTogglePin: true
                )
            )
        }

        if projectFileIndexSnapshot.entries.isEmpty {
            for url in quickSwitcherProjectFileURLs {
                let standardized = url.standardizedFileURL.path
                if fileURLSet.contains(standardized) { continue }
                if items.contains(where: { $0.id == "file:\(standardized)" }) { continue }
                items.append(
                    QuickFileSwitcherPanel.Item(
                        id: "file:\(standardized)",
                        title: url.lastPathComponent,
                        subtitle: standardized,
                        isPinned: false,
                        canTogglePin: true
                    )
                )
            }
        } else {
            for entry in projectFileIndexSnapshot.entries {
                let standardized = entry.standardizedPath
                let subtitle = entry.relativePath == entry.displayName ? standardized : entry.relativePath
                if fileURLSet.contains(standardized) { continue }
                if items.contains(where: { $0.id == "file:\(standardized)" }) { continue }
                items.append(
                    QuickFileSwitcherPanel.Item(
                        id: "file:\(standardized)",
                        title: entry.displayName,
                        subtitle: subtitle,
                        isPinned: false,
                        canTogglePin: true
                    )
                )
            }
        }

        let query = quickSwitcherQuery.trimmingCharacters(in: .whitespacesAndNewlines)
        if query.isEmpty {
            return Array(
                items
                    .sorted {
                        let leftPinned = $0.isPinned ? 1 : 0
                        let rightPinned = $1.isPinned ? 1 : 0
                        if leftPinned != rightPinned {
                            return leftPinned > rightPinned
                        }
                        return quickSwitcherRecencyScore(for: $0.id) > quickSwitcherRecencyScore(for: $1.id)
                    }
                    .prefix(300)
            )
        }

        let ranked = items.compactMap { item -> (QuickFileSwitcherPanel.Item, Int)? in
            guard let score = quickSwitcherMatchScore(for: item, query: query) else { return nil }
            let pinBoost = item.isPinned ? 400 : 0
            return (item, score + quickSwitcherRecencyScore(for: item.id) + pinBoost)
        }
        .sorted {
            if $0.1 == $1.1 {
                return $0.0.title.localizedCaseInsensitiveCompare($1.0.title) == .orderedAscending
            }
            return $0.1 > $1.1
        }

        return Array(ranked.prefix(300).map(\.0))
    }

    private var quickSwitcherStatusMessage: String {
        guard projectRootFolderURL != nil else { return "No project folder is open." }
        if isProjectFileIndexing {
            if projectFileIndexSnapshot.entries.isEmpty {
                return "Indexing project files for Quick Open…"
            }
            return "Refreshing indexed project files…"
        }
        if !projectFileIndexSnapshot.entries.isEmpty {
            let fileCount = projectFileIndexSnapshot.entries.count
            return "Using indexed project files (\(fileCount))."
        }
        if !quickSwitcherProjectFileURLs.isEmpty {
            return "Using the current project tree until indexing is available."
        }
        return "Project files will appear here after the folder is indexed."
    }

    private func selectQuickSwitcherItem(_ item: QuickFileSwitcherPanel.Item) {
        rememberQuickSwitcherSelection(item.id)
        if item.id.hasPrefix("cmd:") {
            performQuickSwitcherCommand(item.id)
            return
        }
        if item.id.hasPrefix("tab:") {
            let raw = String(item.id.dropFirst(4))
            if let id = UUID(uuidString: raw) {
                viewModel.selectTab(id: id)
            }
            return
        }
        if item.id.hasPrefix("file:") {
            let path = String(item.id.dropFirst(5))
            openProjectFile(url: URL(fileURLWithPath: path))
        }
    }

    private func toggleQuickSwitcherPin(_ item: QuickFileSwitcherPanel.Item) {
        guard item.canTogglePin, item.id.hasPrefix("file:") else { return }
        let path = String(item.id.dropFirst(5))
        RecentFilesStore.togglePinned(URL(fileURLWithPath: path))
        recentFilesRefreshToken = UUID()
    }

    var canCreateCodeSnapshot: Bool {
        !normalizedCodeSnapshotSelection().isEmpty
    }

    func presentCodeSnapshotComposer() {
        let selection = normalizedCodeSnapshotSelection()
        guard !selection.isEmpty else { return }
        let title = viewModel.selectedTab?.name ?? "Code Snapshot"
        codeSnapshotPayload = CodeSnapshotPayload(
            title: title,
            language: currentLanguage,
            text: selection
        )
    }

    private func normalizedCodeSnapshotSelection() -> String {
        currentSelectionSnapshotText.trimmingCharacters(in: .whitespacesAndNewlines)
    }

    private func performQuickSwitcherCommand(_ commandID: String) {
        switch commandID {
        case "cmd:new_tab":
            viewModel.addNewTab()
        case "cmd:open_file":
            openFileFromToolbar()
        case "cmd:save_file":
            saveCurrentTabFromToolbar()
        case "cmd:save_as":
            saveCurrentTabAsFromToolbar()
        case "cmd:find_replace":
            showFindReplace = true
        case "cmd:find_in_files":
            showFindInFiles = true
        case "cmd:toggle_sidebar":
            viewModel.showSidebar.toggle()
        default:
            break
        }
    }

    private func rememberQuickSwitcherSelection(_ itemID: String) {
        quickSwitcherRecentItemIDs.removeAll { $0 == itemID }
        quickSwitcherRecentItemIDs.insert(itemID, at: 0)
        if quickSwitcherRecentItemIDs.count > 30 {
            quickSwitcherRecentItemIDs = Array(quickSwitcherRecentItemIDs.prefix(30))
        }
        UserDefaults.standard.set(quickSwitcherRecentItemIDs, forKey: quickSwitcherRecentsDefaultsKey)
    }

    private func quickSwitcherRecencyScore(for itemID: String) -> Int {
        guard let index = quickSwitcherRecentItemIDs.firstIndex(of: itemID) else { return 0 }
        return max(0, 120 - (index * 5))
    }

    private func quickSwitcherPathComponents(for item: QuickFileSwitcherPanel.Item) -> [String] {
        item.subtitle
            .split(separator: "/")
            .map { String($0).lowercased() }
            .filter { !$0.isEmpty }
    }

    private func quickSwitcherTitleStem(for item: QuickFileSwitcherPanel.Item) -> String {
        URL(fileURLWithPath: item.title).deletingPathExtension().lastPathComponent.lowercased()
    }

    private func quickSwitcherTokenPrefixScore(for query: String, in value: String, score: Int) -> Int? {
        let separators = CharacterSet.alphanumerics.inverted
        let tokens = value
            .components(separatedBy: separators)
            .filter { !$0.isEmpty }
        return tokens.contains(where: { $0.hasPrefix(query) }) ? score : nil
    }

    private func quickSwitcherQueryTokens(for query: String) -> [String] {
        query
            .lowercased()
            .split(whereSeparator: { $0.isWhitespace || $0 == "/" || $0 == "_" || $0 == "-" || $0 == "." })
            .map(String.init)
            .filter { !$0.isEmpty }
    }

    private func quickSwitcherMultiTokenScore(
        tokens: [String],
        title: String,
        subtitle: String,
        pathComponents: [String]
    ) -> Int? {
        guard tokens.count > 1 else { return nil }

        let titleTokens = title
            .components(separatedBy: CharacterSet.alphanumerics.inverted)
            .filter { !$0.isEmpty }
        let subtitleTokens = subtitle
            .components(separatedBy: CharacterSet.alphanumerics.inverted)
            .filter { !$0.isEmpty }

        let allTitlePrefix = tokens.allSatisfy { queryToken in
            titleTokens.contains(where: { $0.hasPrefix(queryToken) })
        }
        if allTitlePrefix {
            return 390
        }

        let allPathPrefix = tokens.allSatisfy { queryToken in
            pathComponents.contains(where: { $0.hasPrefix(queryToken) })
        }
        if allPathPrefix {
            return 340
        }

        let allDistributedPrefix = tokens.allSatisfy { queryToken in
            titleTokens.contains(where: { $0.hasPrefix(queryToken) }) ||
            subtitleTokens.contains(where: { $0.hasPrefix(queryToken) }) ||
            pathComponents.contains(where: { $0.hasPrefix(queryToken) })
        }
        if allDistributedPrefix {
            return 300
        }

        return nil
    }

    private func quickSwitcherMatchScore(for item: QuickFileSwitcherPanel.Item, query: String) -> Int? {
        let normalizedQuery = query.lowercased()
        let queryTokens = quickSwitcherQueryTokens(for: query)
        let title = item.title.lowercased()
        let subtitle = item.subtitle.lowercased()
        let titleStem = quickSwitcherTitleStem(for: item)
        let pathComponents = quickSwitcherPathComponents(for: item)
        if title == normalizedQuery {
            return 420
        }
        if titleStem == normalizedQuery {
            return 400
        }
        if let score = quickSwitcherMultiTokenScore(
            tokens: queryTokens,
            title: title,
            subtitle: subtitle,
            pathComponents: pathComponents
        ) {
            return score
        }
        if let score = quickSwitcherTokenPrefixScore(for: normalizedQuery, in: title, score: 370) {
            return score
        }
        if title.hasPrefix(normalizedQuery) {
            return 350
        }
        if pathComponents.contains(normalizedQuery) {
            return 320
        }
        if pathComponents.contains(where: { $0.hasPrefix(normalizedQuery) }) {
            return 290
        }
        if title.contains(normalizedQuery) {
            return 240
        }
        if let score = quickSwitcherTokenPrefixScore(for: normalizedQuery, in: subtitle, score: 210) {
            return score
        }
        if subtitle.contains(normalizedQuery) {
            return 180
        }
        if isFuzzyMatch(needle: normalizedQuery, haystack: title) {
            return 120
        }
        if isFuzzyMatch(needle: normalizedQuery, haystack: subtitle) {
            return 90
        }
        return nil
    }

    private func isFuzzyMatch(needle: String, haystack: String) -> Bool {
        if needle.isEmpty { return true }
        var cursor = haystack.startIndex
        for ch in needle {
            var found = false
            while cursor < haystack.endIndex {
                if haystack[cursor] == ch {
                    found = true
                    cursor = haystack.index(after: cursor)
                    break
                }
                cursor = haystack.index(after: cursor)
            }
            if !found { return false }
        }
        return true
    }

    private func startFindInFiles() {
        guard let root = projectRootFolderURL else {
            findInFilesResults = []
            findInFilesStatusMessage = "Open a project folder first."
            findInFilesSourceMessage = ""
            return
        }
        let query = findInFilesQuery.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !query.isEmpty else {
            findInFilesResults = []
            findInFilesStatusMessage = "Enter a search query."
            findInFilesSourceMessage = ""
            return
        }

        findInFilesTask?.cancel()
        let indexedProjectFileURLs = projectFileIndexSnapshot.fileURLs
        let candidateFiles = indexedProjectFileURLs.isEmpty ? nil : indexedProjectFileURLs
        let searchSourceMessage: String
        if candidateFiles == nil, isProjectFileIndexing {
            findInFilesStatusMessage = "Searching while project index updates…"
            searchSourceMessage = "Live filesystem scan while the project index refreshes."
        } else {
            findInFilesStatusMessage = "Searching…"
            if let candidateFiles {
                searchSourceMessage = "Searching \(candidateFiles.count) indexed project files."
            } else {
                searchSourceMessage = "Searching the live project tree because no index is available yet."
            }
        }
        findInFilesSourceMessage = searchSourceMessage

        let caseSensitive = findInFilesCaseSensitive
        findInFilesTask = Task {
            let results = await ContentView.findInFiles(
                root: root,
                candidateFiles: candidateFiles,
                query: query,
                caseSensitive: caseSensitive,
                maxResults: 500
            )
            guard !Task.isCancelled else { return }
            findInFilesResults = results
            if results.isEmpty {
                findInFilesStatusMessage = "No matches found."
            } else {
                findInFilesStatusMessage = String.localizedStringWithFormat(
                    NSLocalizedString("%lld matches", comment: ""),
                    Int64(results.count)
                )
            }
            findInFilesSourceMessage = searchSourceMessage
        }
    }

    private func clearFindInFiles() {
        findInFilesTask?.cancel()
        findInFilesQuery = ""
        findInFilesResults = []
        findInFilesStatusMessage = ""
        findInFilesSourceMessage = ""
    }

    private func selectFindInFilesMatch(_ match: FindInFilesMatch) {
        openProjectFile(url: match.fileURL)
        var userInfo: [String: Any] = [
            EditorCommandUserInfo.rangeLocation: match.rangeLocation,
            EditorCommandUserInfo.rangeLength: match.rangeLength,
            EditorCommandUserInfo.focusEditor: true
        ]
#if os(macOS)
        if let hostWindowNumber {
            userInfo[EditorCommandUserInfo.windowNumber] = hostWindowNumber
        }
#endif
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.08) {
            NotificationCenter.default.post(name: .moveCursorToRange, object: nil, userInfo: userInfo)
        }
    }

    private func scheduleWordCountRefresh(for text: String) {
        let snapshot = text
        let shouldSkipWordCount = effectiveLargeFileModeEnabled || currentDocumentUTF16Length >= 300_000
        wordCountTask?.cancel()
        wordCountTask = Task(priority: .utility) {
            try? await Task.sleep(nanoseconds: 80_000_000)
            guard !Task.isCancelled else { return }
            let lineCount = Self.lineCount(for: snapshot)
            let wordCount = shouldSkipWordCount ? 0 : viewModel.wordCount(for: snapshot)
            await MainActor.run {
                statusLineCount = lineCount
                statusWordCount = wordCount
            }
        }
    }

}