refactor: extract main window registry and context ownership

Sources/AppDelegate.swift

@@ -593,60 +593,8 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         MacSentryStartupPolicy.isRunningUnderXCTest(environment: env)
     }
 
-    @MainActor
-    final class MainWindowContext {
-        let windowId: UUID
-        let tabManager: TabManager
-        let sidebarState: SidebarState
-        let sidebarSelectionState: SidebarSelectionState
-        var fileExplorerState: FileExplorerState?
-        let keyboardFocusCoordinator: MainWindowFocusController
-        var cmuxConfigStore: CmuxConfigStore?
-        var closeObserver: WindowCloseObserver?
-        weak var window: NSWindow?
-        /// Per-window Dock owned by this context and torn down with it.
-        var windowDock: DockSplitStore?
-        private let workspaceTerminalFontSizeArbiter:
-            WorkspaceTerminalFontSizeArbiter
-        /// Window-scoped font-size queue. Requests contain stable workspace ids;
-        /// teardown cancels the queue before any surface owner is released.
-        lazy var workspaceTerminalFontSizeCoordinator =
-            WorkspaceTerminalFontSizeCoordinator(
-                tabManager: tabManager,
-                arbiter: workspaceTerminalFontSizeArbiter
-            )
-#if DEBUG
-        var debugWorkspaceTerminalFontSizeEnqueueResultOverride: Bool?
-#endif
-
-        init(
-            windowId: UUID,
-            tabManager: TabManager,
-            sidebarState: SidebarState,
-            sidebarSelectionState: SidebarSelectionState,
-            fileExplorerState: FileExplorerState?,
-            cmuxConfigStore: CmuxConfigStore?,
-            window: NSWindow?,
-            workspaceTerminalFontSizeArbiter:
-                WorkspaceTerminalFontSizeArbiter
-        ) {
-            self.windowId = windowId
-            self.tabManager = tabManager
-            self.sidebarState = sidebarState
-            self.sidebarSelectionState = sidebarSelectionState
-            self.fileExplorerState = fileExplorerState
-            self.cmuxConfigStore = cmuxConfigStore
-            self.window = window
-            self.workspaceTerminalFontSizeArbiter =
-                workspaceTerminalFontSizeArbiter
-            self.keyboardFocusCoordinator = MainWindowFocusController(
-                windowId: windowId,
-                window: window,
-                tabManager: tabManager,
-                fileExplorerState: fileExplorerState
-            )
-        }
-    }
+    /// Compatibility name for the independently owned main-window model.
+    typealias MainWindowContext = CmuxMainWindowContext
 
     struct ScriptableMainWindowState {
         let windowId: UUID
@@ -1074,7 +1022,12 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
     }
 #endif
 
-    var mainWindowContexts: [ObjectIdentifier: MainWindowContext] = [:]
+    private let mainWindowRegistry = MainWindowRegistry()
+
+    /// Compatibility view for existing routing and lifecycle callers.
+    var mainWindowContexts: [ObjectIdentifier: MainWindowContext] {
+        mainWindowRegistry.contexts
+    }
     private var mainWindowControllers: [MainWindowController] = []
 
     /// Tracks the cascade point for new windows, matching Ghostty's upstream algorithm.
@@ -4875,6 +4828,13 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         NotificationCenter.default.post(name: .mainWindowContextsDidChange, object: self)
     }
 
+#if DEBUG
+    /// Inserts a windowless test context without exposing the registry storage.
+    func insertMainWindowContextForTesting(_ context: MainWindowContext, key: ObjectIdentifier) {
+        mainWindowRegistry.insert(context, for: key)
+    }
+#endif
+
     func ensureMobileWorkspaceListObserver(for tabManager: TabManager) {
         let id = ObjectIdentifier(tabManager)
         let configStore = mainWindowContext(for: tabManager)?.cmuxConfigStore
@@ -4907,12 +4867,11 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         fileExplorerState: FileExplorerState? = nil,
         cmuxConfigStore: CmuxConfigStore? = nil
     ) {
-        let key = ObjectIdentifier(window)
         forgetRecoverableMainWindowRoute(windowId: windowId)
         #if DEBUG
         let priorManagerToken = debugManagerToken(self.tabManager)
         #endif
-        if let existing = mainWindowContexts[key] {
+        if let existing = mainWindowRegistry.context(for: window) {
             tabManager.window = window
             tabManager.windowId = existing.windowId
             existing.window = window
@@ -4981,7 +4940,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
                 workspaceTerminalFontSizeArbiter:
                     workspaceTerminalFontSizeArbiter
             )
-            mainWindowContexts[key] = context
+            mainWindowRegistry.insert(context, for: window)
             context.closeObserver = WindowCloseObserver(window: window) { [weak self] in self?.unregisterMainWindow($0) }
         }
         commandPaletteWindowStore.registerWindow(windowId)
@@ -6213,33 +6172,15 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
     }
 
     private func reindexMainWindowContextIfNeeded(_ context: MainWindowContext, for window: NSWindow) {
-        let desiredKey = ObjectIdentifier(window)
-        if mainWindowContexts[desiredKey] === context {
-            context.window = window
-            return
-        }
-
-        let contextKeys = mainWindowContexts.compactMap { key, value in
-            value === context ? key : nil
-        }
-        for key in contextKeys {
-            mainWindowContexts.removeValue(forKey: key)
-        }
-
-        if let conflicting = mainWindowContexts[desiredKey], conflicting !== context {
-            context.window = window
-            return
+        if mainWindowRegistry.reindex(context, for: window) {
+            notifyMainWindowContextsDidChange()
         }
-
-        mainWindowContexts[desiredKey] = context
-        context.window = window
-        notifyMainWindowContextsDidChange()
     }
 
     func contextForMainTerminalWindow(_ window: NSWindow, reindex: Bool = true) -> MainWindowContext? {
         guard isMainTerminalWindow(window) else { return nil }
 
-        if let context = mainWindowContexts[ObjectIdentifier(window)] {
+        if let context = mainWindowRegistry.context(for: window) {
             context.window = window
             return context
         }
@@ -6274,12 +6215,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
     private func unregisterMainWindowContext(for window: NSWindow) -> MainWindowContext? {
         guard let removed = contextForMainTerminalWindow(window, reindex: false) else { return nil }
         removed.teardownWindowDock()
-        let removedKeys = mainWindowContexts.compactMap { key, value in
-            value === removed ? key : nil
-        }
-        for key in removedKeys {
-            mainWindowContexts.removeValue(forKey: key)
-        }
+        mainWindowRegistry.removeReferences(to: removed)
         rememberRecoverableMainWindowRoute(windowId: removed.windowId, tabManager: removed.tabManager, window: removed.window)
         removeMobileWorkspaceListObserverIfUnused(for: removed.tabManager)
         notifyMainWindowContextsDidChange()
@@ -6289,12 +6225,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
     // Internal (not private): see notifyMainWindowContextsDidChange.
     func discardOrphanedMainWindowContext(_ context: MainWindowContext, allowWindowlessFallback: Bool = false) {
         context.teardownWindowDock()
-        let contextKeys = mainWindowContexts.compactMap { key, value in
-            value === context ? key : nil
-        }
-        for key in contextKeys {
-            mainWindowContexts.removeValue(forKey: key)
-        }
+        mainWindowRegistry.removeReferences(to: context)
         rememberRecoverableMainWindowRoute(windowId: context.windowId, tabManager: context.tabManager, window: context.window)
         removeMobileWorkspaceListObserverIfUnused(for: context.tabManager)
         notifyMainWindowContextsDidChange()
@@ -6320,7 +6251,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
     }
 
     private func mainWindowId(for window: NSWindow) -> UUID? {
-        if let context = mainWindowContexts[ObjectIdentifier(window)] {
+        if let context = mainWindowRegistry.context(for: window) {
             return context.windowId
         }
         guard let rawIdentifier = window.identifier?.rawValue,
@@ -16064,13 +15995,8 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         )
         debugDetachedContextWindows.append(detachedWindow)
 
-        let contextKeys = mainWindowContexts.compactMap { key, value in
-            value === context ? key : nil
-        }
-        for key in contextKeys {
-            mainWindowContexts.removeValue(forKey: key)
-        }
-        mainWindowContexts[ObjectIdentifier(detachedWindow)] = context
+        mainWindowRegistry.removeReferences(to: context)
+        mainWindowRegistry.insert(context, for: detachedWindow)
         context.window = window
         return true
     }
@@ -17393,7 +17319,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
 #endif
 
     func isMainTerminalWindow(_ window: NSWindow) -> Bool {
-        if mainWindowContexts[ObjectIdentifier(window)] != nil {
+        if mainWindowRegistry.context(for: window) != nil {
             return true
         }
         guard let raw = window.identifier?.rawValue else { return false }

Sources/CmuxMainWindowContext.swift

@@ -0,0 +1,57 @@
+import AppKit
+
+/// Owns the models and resource handles scoped to a single main window.
+@MainActor
+final class CmuxMainWindowContext {
+    let windowId: UUID
+    let tabManager: TabManager
+    let sidebarState: SidebarState
+    let sidebarSelectionState: SidebarSelectionState
+    var fileExplorerState: FileExplorerState?
+    let keyboardFocusCoordinator: MainWindowFocusController
+    var cmuxConfigStore: CmuxConfigStore?
+    var closeObserver: WindowCloseObserver?
+    weak var window: NSWindow?
+    /// Per-window Dock owned by this context and torn down with it.
+    var windowDock: DockSplitStore?
+    private let workspaceTerminalFontSizeArbiter:
+        WorkspaceTerminalFontSizeArbiter
+    /// Window-scoped font-size queue. Requests contain stable workspace ids;
+    /// teardown cancels the queue before any surface owner is released.
+    lazy var workspaceTerminalFontSizeCoordinator =
+        WorkspaceTerminalFontSizeCoordinator(
+            tabManager: tabManager,
+            arbiter: workspaceTerminalFontSizeArbiter
+        )
+#if DEBUG
+    var debugWorkspaceTerminalFontSizeEnqueueResultOverride: Bool?
+#endif
+
+    init(
+        windowId: UUID,
+        tabManager: TabManager,
+        sidebarState: SidebarState,
+        sidebarSelectionState: SidebarSelectionState,
+        fileExplorerState: FileExplorerState?,
+        cmuxConfigStore: CmuxConfigStore?,
+        window: NSWindow?,
+        workspaceTerminalFontSizeArbiter:
+            WorkspaceTerminalFontSizeArbiter
+    ) {
+        self.windowId = windowId
+        self.tabManager = tabManager
+        self.sidebarState = sidebarState
+        self.sidebarSelectionState = sidebarSelectionState
+        self.fileExplorerState = fileExplorerState
+        self.cmuxConfigStore = cmuxConfigStore
+        self.window = window
+        self.workspaceTerminalFontSizeArbiter =
+            workspaceTerminalFontSizeArbiter
+        self.keyboardFocusCoordinator = MainWindowFocusController(
+            windowId: windowId,
+            window: window,
+            tabManager: tabManager,
+            fileExplorerState: fileExplorerState
+        )
+    }
+}

Sources/MainWindowRegistry.swift

@@ -0,0 +1,68 @@
+import AppKit
+
+/// Owns the identity index that maps terminal windows to their main-window contexts.
+@MainActor
+final class MainWindowRegistry {
+    typealias Context = CmuxMainWindowContext
+
+    private(set) var contexts: [ObjectIdentifier: Context] = [:]
+
+    /// Returns the context currently indexed for `window`.
+    func context(for window: NSWindow) -> Context? {
+        contexts[ObjectIdentifier(window)]
+    }
+
+    /// Returns the context currently indexed under `key`.
+    func context(for key: ObjectIdentifier) -> Context? {
+        contexts[key]
+    }
+
+    /// Inserts `context` under the window's identity key.
+    func insert(_ context: Context, for window: NSWindow) {
+        insert(context, for: ObjectIdentifier(window))
+    }
+
+    /// Inserts `context` under an already-resolved identity key.
+    ///
+    /// The key overload keeps test-only windowless contexts on the same mutation
+    /// path without exposing the registry's backing dictionary to callers.
+    func insert(_ context: Context, for key: ObjectIdentifier) {
+        contexts[key] = context
+    }
+
+    /// Removes every key currently referring to `context`.
+    @discardableResult
+    func removeReferences(to context: Context) -> [ObjectIdentifier] {
+        let keys = contexts.compactMap { key, value in
+            value === context ? key : nil
+        }
+        for key in keys {
+            contexts.removeValue(forKey: key)
+        }
+        return keys
+    }
+
+    /// Rebinds a context to a window while preserving duplicate-window conflict behavior.
+    ///
+    /// Returns `true` only when a new index entry was installed. A conflicting entry leaves
+    /// the context unindexed under the requested key, matching the prior AppDelegate logic.
+    @discardableResult
+    func reindex(_ context: Context, for window: NSWindow) -> Bool {
+        let desiredKey = ObjectIdentifier(window)
+        if contexts[desiredKey] === context {
+            context.window = window
+            return false
+        }
+
+        removeReferences(to: context)
+
+        if let conflicting = contexts[desiredKey], conflicting !== context {
+            context.window = window
+            return false
+        }
+
+        contexts[desiredKey] = context
+        context.window = window
+        return true
+    }
+}