macOS: fix App Icon update in Finder (#12344)

Looks like `NSWorkspace.shared.setIcon` can only be called from the main
App, DockTilePlugin is sandboxed and doesn't have the permission to
`file-write-finderinfo`.

<img width="1186" height="144" alt="image"
src="https://github.com/user-attachments/assets/e5ea4f1c-718c-493a-bda2-32787881881e"
/>


It works fine in debug, but not in release. This fixes #11489

macos/Sources/App/macOS/AppDelegate.swift

@@ -151,8 +151,7 @@ class AppDelegate: NSObject,
     /// Signals
     private var signals: [DispatchSourceSignal] = []
 
-    /// The custom app icon image that is currently in use.
-    @Published private(set) var appIcon: NSImage?
+    private let appIconUpdater = AppIconUpdater()
 
     @MainActor private lazy var menuShortcutManager = Ghostty.MenuShortcutManager()
 
@@ -847,13 +846,8 @@ class AppDelegate: NSObject,
     }
 
     private func updateAppIcon(from config: Ghostty.Config) {
-        // Since this is called after `DockTilePlugin` has been running,
-        // clean it up here to trigger a correct update of the current config.
-        UserDefaults.ghostty.removeObject(forKey: "CustomGhosttyIcon")
-        DispatchQueue.global().async {
-            UserDefaults.ghostty.appIcon = AppIcon(config: config)
-            DistributedNotificationCenter.default()
-                .postNotificationName(.ghosttyIconDidChange, object: nil, userInfo: nil, deliverImmediately: true)
+        Task.detached {
+            await self.appIconUpdater.update(icon: AppIcon(config: config))
         }
     }
 

macos/Sources/Features/Custom App Icon/AppIcon.swift

@@ -2,7 +2,7 @@ import AppKit
 import System
 
 /// The icon style for the Ghostty App.
-enum AppIcon: Equatable, Codable {
+enum AppIcon: Equatable, Codable, Sendable {
     case official
     case blueprint
     case chalkboard
@@ -84,3 +84,26 @@ enum AppIcon: Equatable, Codable {
         }
     }
 }
+
+#if !DOCK_TILE_PLUGIN
+/// Making sure that `NSWorkspace.shared.setIcon` executes on only one thread at a time
+actor AppIconUpdater {
+    func update(icon: AppIcon?) {
+        UserDefaults.ghostty.appIcon = icon
+        // Notify DockTilePlugin to update dock icon
+        DistributedNotificationCenter.default()
+            .postNotificationName(
+                .ghosttyIconDidChange,
+                object: nil,
+                userInfo: nil,
+                deliverImmediately: true,
+            )
+
+        NSWorkspace.shared.setIcon(
+            icon?.image(in: .main),
+            forFile: Bundle.main.bundlePath,
+        )
+        NSWorkspace.shared.noteFileSystemChanged(Bundle.main.bundlePath)
+    }
+}
+#endif

macos/Sources/Features/Custom App Icon/ColorizedGhosttyIconImage.swift

@@ -4,12 +4,6 @@ extension View {
     /// Returns the ghostty icon to use for views.
     func ghosttyIconImage() -> Image {
         #if os(macOS)
-        // If we have a specific icon set, then use that
-        if let delegate = NSApplication.shared.delegate as? AppDelegate,
-           let nsImage = delegate.appIcon {
-            return Image(nsImage: nsImage)
-        }
-
         // Grab the icon from the running application. This is the best way
         // I've found so far to get the proper icon for our current icon
         // tinting and so on with macOS Tahoe

macos/Sources/Features/Custom App Icon/DockTilePlugin.swift

@@ -17,32 +17,6 @@ class DockTilePlugin: NSObject, NSDockTilePlugIn {
 
     private var iconChangeObserver: Any?
 
-    /// The URL to the enclosing app bundle, determined from the plugin bundle path.
-    var ghosttyAppURL: URL? {
-        Self.appBundleURL(for: pluginBundle.bundleURL)
-    }
-
-    /// Determine the enclosing app bundle for the dock tile plugin bundle.
-    ///
-    /// We intentionally avoid matching a specific bundle name (such as
-    /// "Ghostty.app") so renaming the app in Finder still works.
-    static func appBundleURL(for pluginBundleURL: URL) -> URL? {
-        var url = pluginBundleURL
-        while true {
-            if url.pathExtension.compare("app", options: .caseInsensitive) == .orderedSame {
-                return url
-            }
-
-            let parent = url.deletingLastPathComponent()
-            if parent.path == url.path {
-                // Safety stop: this should only happen at filesystem root.
-                return nil
-            }
-
-            url = parent
-        }
-    }
-
     /// The primary NSDockTilePlugin function.
     func setDockTile(_ dockTile: NSDockTile?) {
         // If no dock tile or no access to Ghostty defaults, we can't do anything.
@@ -70,25 +44,13 @@ class DockTilePlugin: NSObject, NSDockTilePlugIn {
             return
         }
 
-        if let appBundleURL = self.ghosttyAppURL {
-            let appBundlePath = appBundleURL.path
-            NSWorkspace.shared.setIcon(appIcon, forFile: appBundlePath)
-            NSWorkspace.shared.noteFileSystemChanged(appBundlePath)
-        }
-
         dockTile.setIcon(appIcon)
     }
 
     /// Reset the application icon and dock tile icon to the default.
     private func resetIcon(dockTile: NSDockTile) {
-        let appBundlePath = self.ghosttyAppURL?.path
         let appIcon: NSImage?
         if #available(macOS 26.0, *) {
-            // Reset to the default (glassy) icon.
-            if let appBundlePath {
-                NSWorkspace.shared.setIcon(nil, forFile: appBundlePath)
-            }
-
             #if DEBUG
             // Use the `Blueprint` icon to distinguish Debug from Release builds.
             appIcon = pluginBundle.image(forResource: "BlueprintImage")!
@@ -99,14 +61,6 @@ class DockTilePlugin: NSObject, NSDockTilePlugIn {
         } else {
             // Use the bundled icon to keep the corner radius consistent with pre-Tahoe apps.
             appIcon = pluginBundle.image(forResource: "AppIconImage")!
-            if let appBundlePath {
-                NSWorkspace.shared.setIcon(appIcon, forFile: appBundlePath)
-            }
-        }
-
-        // Notify Finder/Dock so icon caches refresh immediately.
-        if let appBundlePath {
-            NSWorkspace.shared.noteFileSystemChanged(appBundlePath)
         }
         dockTile.setIcon(appIcon)
     }

macos/Sources/Features/Custom App Icon/Extensions/Notification+AppIcon.swift

@@ -1,5 +1,8 @@
 import AppKit
 
 extension Notification.Name {
+    /// Distributed Notification for DockTilePlugin to update icon
+    ///
+    /// Ghostty -> DockTilePlugin
     static let ghosttyIconDidChange = Notification.Name("com.mitchellh.ghostty.iconDidChange")
 }