Add Sparkle auto-update flow and titlebar update UI

.github/workflows/release.yml

@@ -51,6 +51,8 @@ jobs:
           cp -R ghostty/macos/GhosttyKit.xcframework GhosttyKit.xcframework
 
       - name: Build app (Release)
+        env:
+          SPARKLE_PUBLIC_KEY: ${{ secrets.SPARKLE_PUBLIC_KEY }}
         run: |
           xcodebuild -scheme cmux -configuration Release -derivedDataPath build CODE_SIGNING_ALLOWED=NO build
 
@@ -117,10 +119,22 @@ jobs:
           xcrun stapler staple "$DMG_RELEASE"
           xcrun stapler validate "$DMG_RELEASE"
 
+      - name: Generate Sparkle appcast
+        env:
+          SPARKLE_PRIVATE_KEY: ${{ secrets.SPARKLE_PRIVATE_KEY }}
+        run: |
+          if [ -z "$SPARKLE_PRIVATE_KEY" ]; then
+            echo "Missing SPARKLE_PRIVATE_KEY secret" >&2
+            exit 1
+          fi
+          ./scripts/sparkle_generate_appcast.sh cmux-macos.dmg "$GITHUB_REF_NAME" appcast.xml
+
       - name: Upload release asset
         uses: softprops/action-gh-release@v2
         with:
-          files: cmux-macos.dmg
+          files: |
+            cmux-macos.dmg
+            appcast.xml
           generate_release_notes: true
 
       - name: Cleanup keychain

CLAUDE.md

@@ -25,3 +25,4 @@ Notes:
   `APPLE_SIGNING_IDENTITY`, `APPLE_ID`, `APPLE_APP_SPECIFIC_PASSWORD`, `APPLE_TEAM_ID`.
 - The release asset is `cmux-macos.dmg` attached to the tag.
 - README download button points to `releases/latest/download/cmux-macos.dmg`.
+- Versioning: bump the minor version for updates unless explicitly asked otherwise.

GhosttyTabs.xcodeproj/project.pbxproj

@@ -20,7 +20,17 @@
 		A50010A4 /* SplitTree.swift in Sources */ = {isa = PBXBuildFile; fileRef = A50010A0 /* SplitTree.swift */; };
 		A50010A5 /* SplitView.swift in Sources */ = {isa = PBXBuildFile; fileRef = A50010A1 /* SplitView.swift */; };
 		A50010A6 /* TerminalSplitTreeView.swift in Sources */ = {isa = PBXBuildFile; fileRef = A50010A2 /* TerminalSplitTreeView.swift */; };
+		A5001201 /* UpdateController.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001211 /* UpdateController.swift */; };
+		A5001202 /* UpdateDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001212 /* UpdateDelegate.swift */; };
+		A5001203 /* UpdateDriver.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001213 /* UpdateDriver.swift */; };
+		A5001204 /* UpdateViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001214 /* UpdateViewModel.swift */; };
+		A5001205 /* UpdatePill.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001215 /* UpdatePill.swift */; };
+		A5001206 /* UpdateBadge.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001216 /* UpdateBadge.swift */; };
+		A5001207 /* UpdatePopoverView.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001217 /* UpdatePopoverView.swift */; };
+		A5001208 /* UpdateTitlebarAccessory.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001218 /* UpdateTitlebarAccessory.swift */; };
+		A5001209 /* WindowToolbarController.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001219 /* WindowToolbarController.swift */; };
 		A5001100 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = A5001101 /* Assets.xcassets */; };
+		A5001230 /* Sparkle in Frameworks */ = {isa = PBXBuildFile; productRef = A5001231 /* Sparkle */; };
 		84E00D47E4584162AE53BC8D /* xterm-ghostty in Resources */ = {isa = PBXBuildFile; fileRef = B2E7294509CC42FE9191870E /* xterm-ghostty */; };
 		B8F266236A1A3D9A45BD840F /* SidebarResizeUITests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 818DBCD4AB69EB72573E8138 /* SidebarResizeUITests.swift */; };
 /* End PBXBuildFile section */
@@ -66,6 +76,15 @@
 		A50010A0 /* SplitTree.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Splits/SplitTree.swift; sourceTree = "<group>"; };
 		A50010A1 /* SplitView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Splits/SplitView.swift; sourceTree = "<group>"; };
 		A50010A2 /* TerminalSplitTreeView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Splits/TerminalSplitTreeView.swift; sourceTree = "<group>"; };
+		A5001211 /* UpdateController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Update/UpdateController.swift; sourceTree = "<group>"; };
+		A5001212 /* UpdateDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Update/UpdateDelegate.swift; sourceTree = "<group>"; };
+		A5001213 /* UpdateDriver.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Update/UpdateDriver.swift; sourceTree = "<group>"; };
+		A5001214 /* UpdateViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Update/UpdateViewModel.swift; sourceTree = "<group>"; };
+		A5001215 /* UpdatePill.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Update/UpdatePill.swift; sourceTree = "<group>"; };
+		A5001216 /* UpdateBadge.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Update/UpdateBadge.swift; sourceTree = "<group>"; };
+		A5001217 /* UpdatePopoverView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Update/UpdatePopoverView.swift; sourceTree = "<group>"; };
+		A5001218 /* UpdateTitlebarAccessory.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Update/UpdateTitlebarAccessory.swift; sourceTree = "<group>"; };
+		A5001219 /* WindowToolbarController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WindowToolbarController.swift; sourceTree = "<group>"; };
 		818DBCD4AB69EB72573E8138 /* SidebarResizeUITests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SidebarResizeUITests.swift; sourceTree = "<group>"; };
 		A5001101 /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
 		B2E7294509CC42FE9191870E /* xterm-ghostty */ = {isa = PBXFileReference; lastKnownFileType = file; path = "terminfo/78/xterm-ghostty"; sourceTree = "<group>"; };
@@ -77,6 +96,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				A5001006 /* GhosttyKit.xcframework in Frameworks */,
+				A5001230 /* Sparkle in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -138,6 +158,15 @@
 				A50010A0 /* SplitTree.swift */,
 				A50010A1 /* SplitView.swift */,
 				A50010A2 /* TerminalSplitTreeView.swift */,
+				A5001211 /* UpdateController.swift */,
+				A5001212 /* UpdateDelegate.swift */,
+				A5001213 /* UpdateDriver.swift */,
+				A5001214 /* UpdateViewModel.swift */,
+				A5001215 /* UpdatePill.swift */,
+				A5001216 /* UpdateBadge.swift */,
+				A5001217 /* UpdatePopoverView.swift */,
+				A5001218 /* UpdateTitlebarAccessory.swift */,
+				A5001219 /* WindowToolbarController.swift */,
 			);
 			path = Sources;
 			sourceTree = "<group>";
@@ -183,6 +212,9 @@
 			);
 			dependencies = (
 			);
+			packageProductDependencies = (
+				A5001231 /* Sparkle */,
+			);
 			name = GhosttyTabs;
 			productName = GhosttyTabs;
 			productReference = A5001000 /* cmux.app */;
@@ -225,6 +257,9 @@
 				Base,
 			);
 			mainGroup = A5001040;
+			packageReferences = (
+				A5001232 /* XCRemoteSwiftPackageReference "Sparkle" */,
+			);
 			productRefGroup = A5001042 /* Products */;
 			projectDirPath = "";
 			projectRoot = "";
@@ -252,6 +287,15 @@
 				A50010A4 /* SplitTree.swift in Sources */,
 				A50010A5 /* SplitView.swift in Sources */,
 				A50010A6 /* TerminalSplitTreeView.swift in Sources */,
+				A5001201 /* UpdateController.swift in Sources */,
+				A5001202 /* UpdateDelegate.swift in Sources */,
+				A5001203 /* UpdateDriver.swift in Sources */,
+				A5001204 /* UpdateViewModel.swift in Sources */,
+				A5001205 /* UpdatePill.swift in Sources */,
+				A5001206 /* UpdateBadge.swift in Sources */,
+				A5001207 /* UpdatePopoverView.swift in Sources */,
+				A5001208 /* UpdateTitlebarAccessory.swift in Sources */,
+				A5001209 /* WindowToolbarController.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -342,7 +386,7 @@
 				CODE_SIGN_ENTITLEMENTS = "";
 				CODE_SIGN_STYLE = Automatic;
 				COMBINE_HIDPI_IMAGES = YES;
-				CURRENT_PROJECT_VERSION = 5;
+				CURRENT_PROJECT_VERSION = 6;
 				DEVELOPMENT_TEAM = "";
 				ENABLE_HARDENED_RUNTIME = NO;
 				GENERATE_INFOPLIST_FILE = YES;
@@ -352,11 +396,13 @@
 				INFOPLIST_KEY_NSHumanReadableCopyright = "";
 				INFOPLIST_KEY_NSMainStoryboardFile = "";
 				INFOPLIST_KEY_NSPrincipalClass = NSApplication;
+				INFOPLIST_KEY_SUFeedURL = "https://github.com/manaflow-ai/GhosttyTabs/releases/latest/download/appcast.xml";
+				INFOPLIST_KEY_SUPublicEDKey = "$(SPARKLE_PUBLIC_KEY)";
 				LD_RUNPATH_SEARCH_PATHS = (
 					"$(inherited)",
 					"@executable_path/../Frameworks",
 				);
-				MARKETING_VERSION = 1.0.4;
+				MARKETING_VERSION = 1.1.0;
 				OTHER_LDFLAGS = (
 					"-lc++",
 					"-framework",
@@ -385,7 +431,7 @@
 				CODE_SIGN_ENTITLEMENTS = "";
 				CODE_SIGN_STYLE = Automatic;
 				COMBINE_HIDPI_IMAGES = YES;
-				CURRENT_PROJECT_VERSION = 5;
+				CURRENT_PROJECT_VERSION = 6;
 				DEVELOPMENT_TEAM = "";
 				ENABLE_HARDENED_RUNTIME = NO;
 				GENERATE_INFOPLIST_FILE = YES;
@@ -395,11 +441,13 @@
 				INFOPLIST_KEY_NSHumanReadableCopyright = "";
 				INFOPLIST_KEY_NSMainStoryboardFile = "";
 				INFOPLIST_KEY_NSPrincipalClass = NSApplication;
+				INFOPLIST_KEY_SUFeedURL = "https://github.com/manaflow-ai/GhosttyTabs/releases/latest/download/appcast.xml";
+				INFOPLIST_KEY_SUPublicEDKey = "$(SPARKLE_PUBLIC_KEY)";
 				LD_RUNPATH_SEARCH_PATHS = (
 					"$(inherited)",
 					"@executable_path/../Frameworks",
 				);
-				MARKETING_VERSION = 1.0.4;
+				MARKETING_VERSION = 1.1.0;
 				OTHER_LDFLAGS = (
 					"-lc++",
 					"-framework",
@@ -426,10 +474,10 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 5;
+				CURRENT_PROJECT_VERSION = 6;
 				GENERATE_INFOPLIST_FILE = YES;
 				MACOSX_DEPLOYMENT_TARGET = 13.0;
-				MARKETING_VERSION = 1.0.4;
+				MARKETING_VERSION = 1.1.0;
 				ONLY_ACTIVE_ARCH = YES;
 				PRODUCT_BUNDLE_IDENTIFIER = com.cmux.appuitests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
@@ -443,10 +491,10 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 5;
+				CURRENT_PROJECT_VERSION = 6;
 				GENERATE_INFOPLIST_FILE = YES;
 				MACOSX_DEPLOYMENT_TARGET = 13.0;
-				MARKETING_VERSION = 1.0.4;
+				MARKETING_VERSION = 1.1.0;
 				ONLY_ACTIVE_ARCH = YES;
 				PRODUCT_BUNDLE_IDENTIFIER = com.cmux.appuitests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
@@ -457,6 +505,25 @@
 		};
 /* End XCBuildConfiguration section */
 
+/* Begin XCRemoteSwiftPackageReference section */
+		A5001232 /* XCRemoteSwiftPackageReference "Sparkle" */ = {
+			isa = XCRemoteSwiftPackageReference;
+			repositoryURL = "https://github.com/sparkle-project/Sparkle";
+			requirement = {
+				kind = upToNextMajorVersion;
+				minimumVersion = 2.5.1;
+			};
+		};
+/* End XCRemoteSwiftPackageReference section */
+
+/* Begin XCSwiftPackageProductDependency section */
+		A5001231 /* Sparkle */ = {
+			isa = XCSwiftPackageProductDependency;
+			package = A5001232 /* XCRemoteSwiftPackageReference "Sparkle" */;
+			productName = Sparkle;
+		};
+/* End XCSwiftPackageProductDependency section */
+
 /* Begin XCConfigurationList section */
 	A5001060 /* Build configuration list for PBXNativeTarget "GhosttyTabs" */ = {
 		isa = XCConfigurationList;

README.md

@@ -10,6 +10,35 @@ Tag a version like `v0.1.0` and push it to trigger the GitHub Actions release wo
 The workflow builds `GhosttyKit.xcframework`, builds the Release app, signs, notarizes,
 staples, and uploads `cmux-macos.dmg` to the release.
 
+## Auto updates
+
+cmux uses Sparkle with the same update UI flow as upstream Ghostty. The app looks for
+an appcast at:
+
+```
+https://github.com/manaflow-ai/GhosttyTabs/releases/latest/download/appcast.xml
+```
+
+To sign updates, set these secrets for release builds:
+
+- `SPARKLE_PUBLIC_KEY`: Sparkle EdDSA public key (embedded in the app).
+- `SPARKLE_PRIVATE_KEY`: Sparkle EdDSA private key (used when generating appcasts).
+
+You still need to generate and upload `appcast.xml` alongside each release asset.
+
+To generate keys locally (stores the private key in your Keychain and appends values
+to `.env`), run:
+
+```bash
+./scripts/sparkle_generate_keys.sh
+```
+
+For manual appcast generation (uses `SPARKLE_PRIVATE_KEY`):
+
+```bash
+SPARKLE_PRIVATE_KEY=... ./scripts/sparkle_generate_appcast.sh cmux-macos.dmg vX.Y.Z appcast.xml
+```
+
 ### Required GitHub secrets
 
 - `APPLE_CERTIFICATE_BASE64`: Base64-encoded Developer ID Application .p12
@@ -18,3 +47,5 @@ staples, and uploads `cmux-macos.dmg` to the release.
 - `APPLE_ID`: Apple ID used for notarization
 - `APPLE_APP_SPECIFIC_PASSWORD`: App-specific password for the Apple ID
 - `APPLE_TEAM_ID`: Apple Developer Team ID
+- `SPARKLE_PUBLIC_KEY`: Sparkle EdDSA public key for update verification
+- `SPARKLE_PRIVATE_KEY`: Sparkle EdDSA private key for appcast signing

Sources/AppDelegate.swift

@@ -2,12 +2,18 @@ import AppKit
 import CoreServices
 import UserNotifications
 
-final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCenterDelegate {
+final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCenterDelegate, NSMenuItemValidation {
     static var shared: AppDelegate?
 
     weak var tabManager: TabManager?
     weak var notificationStore: TerminalNotificationStore?
     private var workspaceObserver: NSObjectProtocol?
+    private let updateController = UpdateController()
+    private lazy var titlebarAccessoryController = UpdateTitlebarAccessoryController(viewModel: updateViewModel)
+
+    var updateViewModel: UpdateViewModel {
+        updateController.viewModel
+    }
 
     override init() {
         super.init()
@@ -22,6 +28,8 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         ensureApplicationIcon()
         observeDuplicateLaunches()
         configureUserNotifications()
+        updateController.startUpdater()
+        titlebarAccessoryController.start()
     }
 
     func applicationWillTerminate(_ notification: Notification) {
@@ -33,6 +41,14 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         self.notificationStore = notificationStore
     }
 
+    @objc func checkForUpdates(_ sender: Any?) {
+        updateController.checkForUpdates()
+    }
+
+    func validateMenuItem(_ item: NSMenuItem) -> Bool {
+        updateController.validateMenuItem(item)
+    }
+
     private func configureUserNotifications() {
         let actions = [
             UNNotificationAction(

Sources/ContentView.swift

@@ -2,6 +2,7 @@ import AppKit
 import SwiftUI
 
 struct ContentView: View {
+    @ObservedObject var updateViewModel: UpdateViewModel
     @EnvironmentObject var tabManager: TabManager
     @EnvironmentObject var notificationStore: TerminalNotificationStore
     @State private var sidebarWidth: CGFloat = 200
@@ -16,85 +17,85 @@ struct ContentView: View {
 
     var body: some View {
         HStack(spacing: 0) {
-            // Vertical Tabs Sidebar
-            VerticalTabsSidebar(
-                sidebarWidth: sidebarWidth,
-                selection: $sidebarSelection,
-                selectedTabIds: $selectedTabIds,
-                lastSidebarSelectionIndex: $lastSidebarSelectionIndex
-            )
-            .frame(width: sidebarWidth)
-            .background(GeometryReader { proxy in
-                Color.clear
-                    .preference(key: SidebarFramePreferenceKey.self, value: proxy.frame(in: .global))
-            })
-            .overlay(alignment: .trailing) {
-                Color.clear
-                    .frame(width: sidebarHandleWidth)
-                    .contentShape(Rectangle())
-                    .accessibilityIdentifier("SidebarResizer")
-                    .onHover { hovering in
-                        if hovering {
-                            if !isResizerHovering {
-                                NSCursor.resizeLeftRight.push()
-                                isResizerHovering = true
+                // Vertical Tabs Sidebar
+                VerticalTabsSidebar(
+                    sidebarWidth: sidebarWidth,
+                    selection: $sidebarSelection,
+                    selectedTabIds: $selectedTabIds,
+                    lastSidebarSelectionIndex: $lastSidebarSelectionIndex
+                )
+                .frame(width: sidebarWidth)
+                .background(GeometryReader { proxy in
+                    Color.clear
+                        .preference(key: SidebarFramePreferenceKey.self, value: proxy.frame(in: .global))
+                })
+                .overlay(alignment: .trailing) {
+                    Color.clear
+                        .frame(width: sidebarHandleWidth)
+                        .contentShape(Rectangle())
+                        .accessibilityIdentifier("SidebarResizer")
+                        .onHover { hovering in
+                            if hovering {
+                                if !isResizerHovering {
+                                    NSCursor.resizeLeftRight.push()
+                                    isResizerHovering = true
+                                }
+                            } else if isResizerHovering {
+                                if !isResizerDragging {
+                                    NSCursor.pop()
+                                    isResizerHovering = false
+                                }
                             }
-                        } else if isResizerHovering {
-                            if !isResizerDragging {
+                        }
+                        .onDisappear {
+                            if isResizerHovering || isResizerDragging {
                                 NSCursor.pop()
                                 isResizerHovering = false
+                                isResizerDragging = false
                             }
                         }
-                    }
-                    .onDisappear {
-                        if isResizerHovering || isResizerDragging {
-                            NSCursor.pop()
-                            isResizerHovering = false
-                            isResizerDragging = false
-                        }
-                    }
-                    .gesture(
-                        DragGesture(minimumDistance: 0, coordinateSpace: .global)
-                            .onChanged { value in
-                                if !isResizerDragging {
-                                    isResizerDragging = true
-                                    if !isResizerHovering {
-                                        NSCursor.resizeLeftRight.push()
-                                        isResizerHovering = true
+                        .gesture(
+                            DragGesture(minimumDistance: 0, coordinateSpace: .global)
+                                .onChanged { value in
+                                    if !isResizerDragging {
+                                        isResizerDragging = true
+                                        if !isResizerHovering {
+                                            NSCursor.resizeLeftRight.push()
+                                            isResizerHovering = true
+                                        }
+                                    }
+                                    let nextWidth = max(140, min(360, value.location.x - sidebarMinX + sidebarHandleWidth / 2))
+                                    withTransaction(Transaction(animation: nil)) {
+                                        sidebarWidth = nextWidth
                                     }
                                 }
-                                let nextWidth = max(140, min(360, value.location.x - sidebarMinX + sidebarHandleWidth / 2))
-                                withTransaction(Transaction(animation: nil)) {
-                                    sidebarWidth = nextWidth
-                                }
-                            }
-                            .onEnded { _ in
-                                if isResizerDragging {
-                                    isResizerDragging = false
-                                    if !isResizerHovering {
-                                        NSCursor.pop()
+                                .onEnded { _ in
+                                    if isResizerDragging {
+                                        isResizerDragging = false
+                                        if !isResizerHovering {
+                                            NSCursor.pop()
+                                        }
                                     }
                                 }
-                            }
-                    )
-            }
-
-            // Terminal Content - use ZStack to keep all surfaces alive
-            ZStack {
-                ZStack {
-                    ForEach(tabManager.tabs) { tab in
-                        let isActive = tabManager.selectedTabId == tab.id
-                        TerminalSplitTreeView(tab: tab, isTabActive: isActive)
-                            .opacity(isActive ? 1 : 0)
-                            .allowsHitTesting(isActive)
-                            .focusable()
-                            .focused($focusedTabId, equals: tab.id)
-                    }
+                        )
                 }
-                .opacity(sidebarSelection == .tabs ? 1 : 0)
-                .allowsHitTesting(sidebarSelection == .tabs)
 
-                NotificationsPage(selection: $sidebarSelection)
+                // Terminal Content - use ZStack to keep all surfaces alive
+                ZStack {
+                    ZStack {
+                        ForEach(tabManager.tabs) { tab in
+                            let isActive = tabManager.selectedTabId == tab.id
+                            TerminalSplitTreeView(tab: tab, isTabActive: isActive)
+                                .opacity(isActive ? 1 : 0)
+                                .allowsHitTesting(isActive)
+                                .focusable()
+                                .focused($focusedTabId, equals: tab.id)
+                        }
+                    }
+                    .opacity(sidebarSelection == .tabs ? 1 : 0)
+                    .allowsHitTesting(sidebarSelection == .tabs)
+
+                    NotificationsPage(selection: $sidebarSelection)
                     .opacity(sidebarSelection == .notifications ? 1 : 0)
                     .allowsHitTesting(sidebarSelection == .notifications)
             }
@@ -139,6 +140,7 @@ struct ContentView: View {
             sidebarMinX = frame.minX
         }
     }
+
 }
 
 struct VerticalTabsSidebar: View {

Sources/TabManager.swift

@@ -220,6 +220,7 @@ class TabManager: ObservableObject {
             let previousTabId = oldValue
             DispatchQueue.main.async { [weak self] in
                 self?.focusSelectedTabSurface(previousTabId: previousTabId)
+                self?.updateWindowTitleForSelectedTab()
             }
         }
     }
@@ -399,9 +400,37 @@ class TabManager: ObservableObject {
         guard let index = tabs.firstIndex(where: { $0.id == tabId }) else { return }
         if tabs[index].title != title {
             tabs[index].title = title
+            if selectedTabId == tabId {
+                updateWindowTitle(for: tabs[index])
+            }
         }
     }
 
+    private func updateWindowTitleForSelectedTab() {
+        guard let selectedTabId,
+              let tab = tabs.first(where: { $0.id == selectedTabId }) else {
+            updateWindowTitle(for: nil)
+            return
+        }
+        updateWindowTitle(for: tab)
+    }
+
+    private func updateWindowTitle(for tab: Tab?) {
+        let title = windowTitle(for: tab)
+        let targetWindow = NSApp.keyWindow ?? NSApp.mainWindow ?? NSApp.windows.first
+        targetWindow?.title = title
+    }
+
+    private func windowTitle(for tab: Tab?) -> String {
+        guard let tab else { return "cmux" }
+        let trimmedTitle = tab.title.trimmingCharacters(in: .whitespacesAndNewlines)
+        if !trimmedTitle.isEmpty {
+            return trimmedTitle
+        }
+        let trimmedDirectory = tab.currentDirectory.trimmingCharacters(in: .whitespacesAndNewlines)
+        return trimmedDirectory.isEmpty ? "cmux" : trimmedDirectory
+    }
+
     func focusTab(_ tabId: UUID, surfaceId: UUID? = nil) {
         guard tabs.contains(where: { $0.id == tabId }) else { return }
         selectedTabId = tabId

Sources/Update/UpdateBadge.swift

@@ -0,0 +1,65 @@
+import SwiftUI
+
+/// A badge view that displays the current state of an update operation.
+struct UpdateBadge: View {
+    @ObservedObject var model: UpdateViewModel
+    @State private var rotationAngle: Double = 0
+
+    var body: some View {
+        badgeContent
+            .accessibilityLabel(model.text)
+    }
+
+    @ViewBuilder
+    private var badgeContent: some View {
+        switch model.state {
+        case .downloading(let download):
+            if let expectedLength = download.expectedLength, expectedLength > 0 {
+                let progress = min(1, max(0, Double(download.progress) / Double(expectedLength)))
+                ProgressRingView(progress: progress)
+            } else {
+                Image(systemName: "arrow.down.circle")
+            }
+
+        case .extracting(let extracting):
+            ProgressRingView(progress: min(1, max(0, extracting.progress)))
+
+        case .checking:
+            if let iconName = model.iconName {
+                Image(systemName: iconName)
+                    .rotationEffect(.degrees(rotationAngle))
+                    .onAppear {
+                        withAnimation(.linear(duration: 2.5).repeatForever(autoreverses: false)) {
+                            rotationAngle = 360
+                        }
+                    }
+                    .onDisappear {
+                        rotationAngle = 0
+                    }
+            }
+
+        default:
+            if let iconName = model.iconName {
+                Image(systemName: iconName)
+            }
+        }
+    }
+}
+
+fileprivate struct ProgressRingView: View {
+    let progress: Double
+    let lineWidth: CGFloat = 2
+
+    var body: some View {
+        ZStack {
+            Circle()
+                .stroke(Color.primary.opacity(0.2), lineWidth: lineWidth)
+
+            Circle()
+                .trim(from: 0, to: progress)
+                .stroke(Color.primary, style: StrokeStyle(lineWidth: lineWidth, lineCap: .round))
+                .rotationEffect(.degrees(-90))
+                .animation(.easeInOut(duration: 0.2), value: progress)
+        }
+    }
+}

Sources/Update/UpdateController.swift

@@ -0,0 +1,90 @@
+import Sparkle
+import Cocoa
+import Combine
+
+/// Controller for managing Sparkle updates in cmux.
+class UpdateController {
+    private(set) var updater: SPUUpdater
+    private let userDriver: UpdateDriver
+    private var installCancellable: AnyCancellable?
+
+    var viewModel: UpdateViewModel {
+        userDriver.viewModel
+    }
+
+    /// True if we're force-installing an update.
+    var isInstalling: Bool {
+        installCancellable != nil
+    }
+
+    init() {
+        let hostBundle = Bundle.main
+        self.userDriver = UpdateDriver(viewModel: .init(), hostBundle: hostBundle)
+        self.updater = SPUUpdater(
+            hostBundle: hostBundle,
+            applicationBundle: hostBundle,
+            userDriver: userDriver,
+            delegate: userDriver
+        )
+    }
+
+    deinit {
+        installCancellable?.cancel()
+    }
+
+    /// Start the updater. If startup fails, the error is shown via the custom UI.
+    func startUpdater() {
+        do {
+            try updater.start()
+        } catch {
+            userDriver.viewModel.state = .error(.init(
+                error: error,
+                retry: { [weak self] in
+                    self?.userDriver.viewModel.state = .idle
+                    self?.startUpdater()
+                },
+                dismiss: { [weak self] in
+                    self?.userDriver.viewModel.state = .idle
+                }
+            ))
+        }
+    }
+
+    /// Force install the current update by auto-confirming all installable states.
+    func installUpdate() {
+        guard viewModel.state.isInstallable else { return }
+        guard installCancellable == nil else { return }
+
+        installCancellable = viewModel.$state.sink { [weak self] state in
+            guard let self else { return }
+            guard state.isInstallable else {
+                self.installCancellable = nil
+                return
+            }
+            state.confirm()
+        }
+    }
+
+    /// Check for updates (used by the menu item).
+    @objc func checkForUpdates() {
+        if viewModel.state == .idle {
+            updater.checkForUpdates()
+            return
+        }
+
+        installCancellable?.cancel()
+        viewModel.state.cancel()
+
+        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(100)) { [weak self] in
+            self?.updater.checkForUpdates()
+        }
+    }
+
+    /// Validate the check for updates menu item.
+    func validateMenuItem(_ item: NSMenuItem) -> Bool {
+        if item.action == #selector(checkForUpdates) {
+            return updater.canCheckForUpdates
+        }
+        return true
+    }
+}

Sources/Update/UpdateDelegate.swift

@@ -0,0 +1,28 @@
+import Sparkle
+import Cocoa
+
+extension UpdateDriver: SPUUpdaterDelegate {
+    func feedURLString(for updater: SPUUpdater) -> String? {
+        Bundle.main.object(forInfoDictionaryKey: "SUFeedURL") as? String
+    }
+
+    /// Called when an update is scheduled to install silently,
+    /// which occurs when automatic download is enabled.
+    func updater(_ updater: SPUUpdater, willInstallUpdateOnQuit item: SUAppcastItem, immediateInstallationBlock immediateInstallHandler: @escaping () -> Void) -> Bool {
+        viewModel.state = .installing(.init(
+            isAutoUpdate: true,
+            retryTerminatingApplication: immediateInstallHandler,
+            dismiss: { [weak viewModel] in
+                viewModel?.state = .idle
+            }
+        ))
+        return true
+    }
+
+    func updaterWillRelaunchApplication(_ updater: SPUUpdater) {
+        NSApp.invalidateRestorableState()
+        for window in NSApp.windows {
+            window.invalidateRestorableState()
+        }
+    }
+}

Sources/Update/UpdateDriver.swift

@@ -0,0 +1,181 @@
+import Cocoa
+import Sparkle
+
+/// SPUUserDriver that updates the view model for custom update UI.
+class UpdateDriver: NSObject, SPUUserDriver {
+    let viewModel: UpdateViewModel
+    let standard: SPUStandardUserDriver
+
+    init(viewModel: UpdateViewModel, hostBundle: Bundle) {
+        self.viewModel = viewModel
+        self.standard = SPUStandardUserDriver(hostBundle: hostBundle, delegate: nil)
+        super.init()
+    }
+
+    func show(_ request: SPUUpdatePermissionRequest,
+              reply: @escaping @Sendable (SUUpdatePermissionResponse) -> Void) {
+        viewModel.state = .permissionRequest(.init(request: request, reply: { [weak viewModel] response in
+            viewModel?.state = .idle
+            reply(response)
+        }))
+        if !hasUnobtrusiveTarget {
+            standard.show(request, reply: reply)
+        }
+    }
+
+    func showUserInitiatedUpdateCheck(cancellation: @escaping () -> Void) {
+        viewModel.state = .checking(.init(cancel: cancellation))
+        if !hasUnobtrusiveTarget {
+            standard.showUserInitiatedUpdateCheck(cancellation: cancellation)
+        }
+    }
+
+    func showUpdateFound(with appcastItem: SUAppcastItem,
+                         state: SPUUserUpdateState,
+                         reply: @escaping @Sendable (SPUUserUpdateChoice) -> Void) {
+        viewModel.state = .updateAvailable(.init(appcastItem: appcastItem, reply: reply))
+        if !hasUnobtrusiveTarget {
+            standard.showUpdateFound(with: appcastItem, state: state, reply: reply)
+        }
+    }
+
+    func showUpdateReleaseNotes(with downloadData: SPUDownloadData) {
+        // cmux uses Sparkle's UI for release notes links instead.
+    }
+
+    func showUpdateReleaseNotesFailedToDownloadWithError(_ error: any Error) {
+        // Release notes are handled via link buttons.
+    }
+
+    func showUpdateNotFoundWithError(_ error: any Error,
+                                     acknowledgement: @escaping () -> Void) {
+        viewModel.state = .notFound(.init(acknowledgement: acknowledgement))
+
+        if !hasUnobtrusiveTarget {
+            standard.showUpdateNotFoundWithError(error, acknowledgement: acknowledgement)
+        }
+    }
+
+    func showUpdaterError(_ error: any Error,
+                          acknowledgement: @escaping () -> Void) {
+        viewModel.state = .error(.init(
+            error: error,
+            retry: { [weak viewModel] in
+                viewModel?.state = .idle
+                DispatchQueue.main.async {
+                    guard let delegate = NSApp.delegate as? AppDelegate else { return }
+                    delegate.checkForUpdates(nil)
+                }
+            },
+            dismiss: { [weak viewModel] in
+                viewModel?.state = .idle
+            }))
+
+        if !hasUnobtrusiveTarget {
+            standard.showUpdaterError(error, acknowledgement: acknowledgement)
+        } else {
+            acknowledgement()
+        }
+    }
+
+    func showDownloadInitiated(cancellation: @escaping () -> Void) {
+        viewModel.state = .downloading(.init(
+            cancel: cancellation,
+            expectedLength: nil,
+            progress: 0))
+
+        if !hasUnobtrusiveTarget {
+            standard.showDownloadInitiated(cancellation: cancellation)
+        }
+    }
+
+    func showDownloadDidReceiveExpectedContentLength(_ expectedContentLength: UInt64) {
+        guard case let .downloading(downloading) = viewModel.state else {
+            return
+        }
+
+        viewModel.state = .downloading(.init(
+            cancel: downloading.cancel,
+            expectedLength: expectedContentLength,
+            progress: 0))
+
+        if !hasUnobtrusiveTarget {
+            standard.showDownloadDidReceiveExpectedContentLength(expectedContentLength)
+        }
+    }
+
+    func showDownloadDidReceiveData(ofLength length: UInt64) {
+        guard case let .downloading(downloading) = viewModel.state else {
+            return
+        }
+
+        viewModel.state = .downloading(.init(
+            cancel: downloading.cancel,
+            expectedLength: downloading.expectedLength,
+            progress: downloading.progress + length))
+
+        if !hasUnobtrusiveTarget {
+            standard.showDownloadDidReceiveData(ofLength: length)
+        }
+    }
+
+    func showDownloadDidStartExtractingUpdate() {
+        viewModel.state = .extracting(.init(progress: 0))
+
+        if !hasUnobtrusiveTarget {
+            standard.showDownloadDidStartExtractingUpdate()
+        }
+    }
+
+    func showExtractionReceivedProgress(_ progress: Double) {
+        viewModel.state = .extracting(.init(progress: progress))
+
+        if !hasUnobtrusiveTarget {
+            standard.showExtractionReceivedProgress(progress)
+        }
+    }
+
+    func showReady(toInstallAndRelaunch reply: @escaping @Sendable (SPUUserUpdateChoice) -> Void) {
+        if !hasUnobtrusiveTarget {
+            standard.showReady(toInstallAndRelaunch: reply)
+        } else {
+            reply(.install)
+        }
+    }
+
+    func showInstallingUpdate(withApplicationTerminated applicationTerminated: Bool, retryTerminatingApplication: @escaping () -> Void) {
+        viewModel.state = .installing(.init(
+            retryTerminatingApplication: retryTerminatingApplication,
+            dismiss: { [weak viewModel] in
+                viewModel?.state = .idle
+            }
+        ))
+
+        if !hasUnobtrusiveTarget {
+            standard.showInstallingUpdate(withApplicationTerminated: applicationTerminated, retryTerminatingApplication: retryTerminatingApplication)
+        }
+    }
+
+    func showUpdateInstalledAndRelaunched(_ relaunched: Bool, acknowledgement: @escaping () -> Void) {
+        standard.showUpdateInstalledAndRelaunched(relaunched, acknowledgement: acknowledgement)
+        viewModel.state = .idle
+    }
+
+    func showUpdateInFocus() {
+        if !hasUnobtrusiveTarget {
+            standard.showUpdateInFocus()
+        }
+    }
+
+    func dismissUpdateInstallation() {
+        viewModel.state = .idle
+        standard.dismissUpdateInstallation()
+    }
+
+    // MARK: No-Window Fallback
+
+    /// True if there is a target that can render our unobtrusive update checker.
+    var hasUnobtrusiveTarget: Bool {
+        NSApp.windows.contains { $0.isVisible }
+    }
+}

Sources/Update/UpdatePill.swift

@@ -0,0 +1,96 @@
+import AppKit
+import SwiftUI
+
+/// A pill-shaped button that displays update status and provides access to update actions.
+struct UpdatePill: View {
+    @ObservedObject var model: UpdateViewModel
+    var showWhenIdle: Bool = false
+    var idleText: String = "Check for Updates"
+    var onIdleTap: (() -> Void)?
+    @State private var showPopover = false
+    @State private var resetTask: Task<Void, Never>?
+
+    private let textFont = NSFont.systemFont(ofSize: 11, weight: .medium)
+
+    var body: some View {
+        if !model.state.isIdle || showWhenIdle {
+            pillButton
+                .popover(isPresented: $showPopover, arrowEdge: .bottom) {
+                    UpdatePopoverView(model: model)
+                }
+                .transition(.opacity.combined(with: .scale(scale: 0.95)))
+                .onChange(of: model.state) { newState in
+                    resetTask?.cancel()
+                    if case .notFound(let notFound) = newState {
+                        resetTask = Task { [weak model] in
+                            try? await Task.sleep(for: .seconds(5))
+                            guard !Task.isCancelled, case .notFound? = model?.state else { return }
+                            model?.state = .idle
+                            notFound.acknowledgement()
+                        }
+                    } else {
+                        resetTask = nil
+                    }
+                }
+        }
+    }
+
+    @ViewBuilder
+    private var pillButton: some View {
+        Button(action: {
+            if model.state.isIdle && showWhenIdle {
+                if let onIdleTap {
+                    onIdleTap()
+                } else {
+                    showPopover.toggle()
+                }
+                return
+            }
+            if case .notFound(let notFound) = model.state {
+                model.state = .idle
+                notFound.acknowledgement()
+            } else {
+                showPopover.toggle()
+            }
+        }) {
+            HStack(spacing: 6) {
+                if model.state.isIdle && showWhenIdle {
+                    Image(systemName: "arrow.triangle.2.circlepath")
+                        .foregroundColor(.secondary)
+                        .frame(width: 14, height: 14)
+                } else {
+                    UpdateBadge(model: model)
+                        .frame(width: 14, height: 14)
+                }
+
+                Text(displayText)
+                    .font(Font(textFont))
+                    .lineLimit(1)
+                    .truncationMode(.tail)
+                    .frame(width: textWidth)
+            }
+            .padding(.horizontal, 8)
+            .padding(.vertical, 4)
+            .background(
+                Capsule()
+                    .fill(model.backgroundColor)
+            )
+            .foregroundColor(model.foregroundColor)
+            .contentShape(Capsule())
+        }
+        .buttonStyle(.plain)
+        .help(displayText)
+        .accessibilityLabel(displayText)
+    }
+
+    private var textWidth: CGFloat? {
+        let attributes: [NSAttributedString.Key: Any] = [.font: textFont]
+        let text = model.state.isIdle && showWhenIdle ? idleText : model.maxWidthText
+        let size = (text as NSString).size(withAttributes: attributes)
+        return size.width
+    }
+
+    private var displayText: String {
+        model.state.isIdle && showWhenIdle ? idleText : model.text
+    }
+}

Sources/Update/UpdatePopoverView.swift

@@ -0,0 +1,377 @@
+import AppKit
+import SwiftUI
+import Sparkle
+
+/// Popover view that displays detailed update information and actions.
+struct UpdatePopoverView: View {
+    @ObservedObject var model: UpdateViewModel
+    @Environment(\.dismiss) private var dismiss
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 0) {
+            switch model.state {
+            case .idle:
+                EmptyView()
+
+            case .permissionRequest(let request):
+                PermissionRequestView(request: request, dismiss: dismiss)
+
+            case .checking(let checking):
+                CheckingView(checking: checking, dismiss: dismiss)
+
+            case .updateAvailable(let update):
+                UpdateAvailableView(update: update, dismiss: dismiss)
+
+            case .downloading(let download):
+                DownloadingView(download: download, dismiss: dismiss)
+
+            case .extracting(let extracting):
+                ExtractingView(extracting: extracting)
+
+            case .installing(let installing):
+                InstallingView(installing: installing, dismiss: dismiss)
+
+            case .notFound(let notFound):
+                NotFoundView(notFound: notFound, dismiss: dismiss)
+
+            case .error(let error):
+                UpdateErrorView(error: error, dismiss: dismiss)
+            }
+        }
+        .frame(width: 300)
+    }
+}
+
+fileprivate struct PermissionRequestView: View {
+    let request: UpdateState.PermissionRequest
+    let dismiss: DismissAction
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 16) {
+            VStack(alignment: .leading, spacing: 8) {
+                Text("Enable automatic updates?")
+                    .font(.system(size: 13, weight: .semibold))
+
+                Text("cmux can automatically check for updates in the background.")
+                    .font(.system(size: 11))
+                    .foregroundColor(.secondary)
+                    .fixedSize(horizontal: false, vertical: true)
+            }
+
+            HStack(spacing: 8) {
+                Button("Not Now") {
+                    request.reply(SUUpdatePermissionResponse(
+                        automaticUpdateChecks: false,
+                        sendSystemProfile: false))
+                    dismiss()
+                }
+                .keyboardShortcut(.cancelAction)
+
+                Spacer()
+
+                Button("Allow") {
+                    request.reply(SUUpdatePermissionResponse(
+                        automaticUpdateChecks: true,
+                        sendSystemProfile: false))
+                    dismiss()
+                }
+                .keyboardShortcut(.defaultAction)
+                .buttonStyle(.borderedProminent)
+            }
+        }
+        .padding(16)
+    }
+}
+
+fileprivate struct CheckingView: View {
+    let checking: UpdateState.Checking
+    let dismiss: DismissAction
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 16) {
+            HStack(spacing: 10) {
+                ProgressView()
+                    .controlSize(.small)
+                Text("Checking for updates…")
+                    .font(.system(size: 13))
+            }
+
+            HStack {
+                Spacer()
+                Button("Cancel") {
+                    checking.cancel()
+                    dismiss()
+                }
+                .keyboardShortcut(.cancelAction)
+                .controlSize(.small)
+            }
+        }
+        .padding(16)
+    }
+}
+
+fileprivate struct UpdateAvailableView: View {
+    let update: UpdateState.UpdateAvailable
+    let dismiss: DismissAction
+
+    private let labelWidth: CGFloat = 60
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 0) {
+            VStack(alignment: .leading, spacing: 12) {
+                VStack(alignment: .leading, spacing: 8) {
+                    Text("Update Available")
+                        .font(.system(size: 13, weight: .semibold))
+
+                    VStack(alignment: .leading, spacing: 4) {
+                        HStack(spacing: 6) {
+                            Text("Version:")
+                                .foregroundColor(.secondary)
+                                .frame(width: labelWidth, alignment: .trailing)
+                            Text(update.appcastItem.displayVersionString)
+                        }
+                        .font(.system(size: 11))
+
+                        if update.appcastItem.contentLength > 0 {
+                            HStack(spacing: 6) {
+                                Text("Size:")
+                                    .foregroundColor(.secondary)
+                                    .frame(width: labelWidth, alignment: .trailing)
+                                Text(ByteCountFormatter.string(fromByteCount: Int64(update.appcastItem.contentLength), countStyle: .file))
+                            }
+                            .font(.system(size: 11))
+                        }
+
+                        if let date = update.appcastItem.date {
+                            HStack(spacing: 6) {
+                                Text("Released:")
+                                    .foregroundColor(.secondary)
+                                    .frame(width: labelWidth, alignment: .trailing)
+                                Text(date.formatted(date: .abbreviated, time: .omitted))
+                            }
+                            .font(.system(size: 11))
+                        }
+                    }
+                    .textSelection(.enabled)
+                }
+
+                HStack(spacing: 8) {
+                    Button("Skip") {
+                        update.reply(.skip)
+                        dismiss()
+                    }
+                    .controlSize(.small)
+
+                    Button("Later") {
+                        update.reply(.dismiss)
+                        dismiss()
+                    }
+                    .controlSize(.small)
+                    .keyboardShortcut(.cancelAction)
+
+                    Spacer()
+
+                    Button("Install and Relaunch") {
+                        update.reply(.install)
+                        dismiss()
+                    }
+                    .keyboardShortcut(.defaultAction)
+                    .buttonStyle(.borderedProminent)
+                    .controlSize(.small)
+                }
+            }
+            .padding(16)
+
+            if let notes = update.releaseNotes {
+                Divider()
+
+                Link(destination: notes.url) {
+                    HStack {
+                        Image(systemName: "doc.text")
+                            .font(.system(size: 11))
+                        Text(notes.label)
+                            .font(.system(size: 11, weight: .medium))
+                        Spacer()
+                        Image(systemName: "arrow.up.right")
+                            .font(.system(size: 10))
+                    }
+                    .foregroundColor(.primary)
+                    .padding(12)
+                    .frame(maxWidth: .infinity)
+                    .background(Color(nsColor: .controlBackgroundColor))
+                    .contentShape(Rectangle())
+                }
+                .buttonStyle(.plain)
+            }
+        }
+    }
+}
+
+fileprivate struct DownloadingView: View {
+    let download: UpdateState.Downloading
+    let dismiss: DismissAction
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 16) {
+            VStack(alignment: .leading, spacing: 8) {
+                Text("Downloading Update")
+                    .font(.system(size: 13, weight: .semibold))
+
+                if let expectedLength = download.expectedLength, expectedLength > 0 {
+                    let progress = min(1, max(0, Double(download.progress) / Double(expectedLength)))
+                    VStack(alignment: .leading, spacing: 6) {
+                        ProgressView(value: progress)
+                        Text(String(format: "%.0f%%", progress * 100))
+                            .font(.system(size: 11))
+                            .foregroundColor(.secondary)
+                    }
+                } else {
+                    ProgressView()
+                        .controlSize(.small)
+                }
+            }
+
+            HStack {
+                Spacer()
+                Button("Cancel") {
+                    download.cancel()
+                    dismiss()
+                }
+                .keyboardShortcut(.cancelAction)
+                .controlSize(.small)
+            }
+        }
+        .padding(16)
+    }
+}
+
+fileprivate struct ExtractingView: View {
+    let extracting: UpdateState.Extracting
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 8) {
+            Text("Preparing Update")
+                .font(.system(size: 13, weight: .semibold))
+
+            VStack(alignment: .leading, spacing: 6) {
+                ProgressView(value: min(1, max(0, extracting.progress)), total: 1.0)
+                Text(String(format: "%.0f%%", min(1, max(0, extracting.progress)) * 100))
+                    .font(.system(size: 11))
+                    .foregroundColor(.secondary)
+            }
+        }
+        .padding(16)
+    }
+}
+
+fileprivate struct InstallingView: View {
+    let installing: UpdateState.Installing
+    let dismiss: DismissAction
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 16) {
+            VStack(alignment: .leading, spacing: 8) {
+                Text("Restart Required")
+                    .font(.system(size: 13, weight: .semibold))
+
+                Text("The update is ready. Please restart the application to complete the installation.")
+                    .font(.system(size: 11))
+                    .foregroundColor(.secondary)
+                    .fixedSize(horizontal: false, vertical: true)
+            }
+
+            HStack {
+                Button("Restart Later") {
+                    installing.dismiss()
+                    dismiss()
+                }
+                .keyboardShortcut(.cancelAction)
+                .controlSize(.small)
+
+                Spacer()
+
+                Button("Restart Now") {
+                    installing.retryTerminatingApplication()
+                    dismiss()
+                }
+                .keyboardShortcut(.defaultAction)
+                .buttonStyle(.borderedProminent)
+                .controlSize(.small)
+            }
+        }
+        .padding(16)
+    }
+}
+
+fileprivate struct NotFoundView: View {
+    let notFound: UpdateState.NotFound
+    let dismiss: DismissAction
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 16) {
+            VStack(alignment: .leading, spacing: 8) {
+                Text("No Updates Found")
+                    .font(.system(size: 13, weight: .semibold))
+
+                Text("You're already running the latest version.")
+                    .font(.system(size: 11))
+                    .foregroundColor(.secondary)
+                    .fixedSize(horizontal: false, vertical: true)
+            }
+
+            HStack {
+                Spacer()
+                Button("OK") {
+                    notFound.acknowledgement()
+                    dismiss()
+                }
+                .keyboardShortcut(.defaultAction)
+                .controlSize(.small)
+            }
+        }
+        .padding(16)
+    }
+}
+
+fileprivate struct UpdateErrorView: View {
+    let error: UpdateState.Error
+    let dismiss: DismissAction
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 16) {
+            VStack(alignment: .leading, spacing: 8) {
+                HStack(spacing: 8) {
+                    Image(systemName: "exclamationmark.triangle.fill")
+                        .foregroundColor(.orange)
+                        .font(.system(size: 13))
+                    Text("Update Failed")
+                        .font(.system(size: 13, weight: .semibold))
+                }
+
+                Text(error.error.localizedDescription)
+                    .font(.system(size: 11))
+                    .foregroundColor(.secondary)
+                    .fixedSize(horizontal: false, vertical: true)
+            }
+
+            HStack(spacing: 8) {
+                Button("OK") {
+                    error.dismiss()
+                    dismiss()
+                }
+                .keyboardShortcut(.cancelAction)
+                .controlSize(.small)
+
+                Spacer()
+
+                Button("Retry") {
+                    error.retry()
+                    dismiss()
+                }
+                .keyboardShortcut(.defaultAction)
+                .controlSize(.small)
+            }
+        }
+        .padding(16)
+    }
+}

Sources/Update/UpdateTitlebarAccessory.swift

@@ -0,0 +1,128 @@
+import AppKit
+import Combine
+import SwiftUI
+
+final class NonDraggableHostingView<Content: View>: NSHostingView<Content> {
+    override var mouseDownCanMoveWindow: Bool { false }
+}
+
+private struct TitlebarAccessoryView: View {
+    @ObservedObject var model: UpdateViewModel
+    let onIdleTap: () -> Void
+
+    var body: some View {
+        UpdatePill(
+            model: model,
+            showWhenIdle: false,
+            onIdleTap: onIdleTap
+        )
+        .fixedSize()
+        .padding(.top, 4)
+        .padding(.trailing, 8)
+    }
+}
+
+final class UpdateAccessoryViewController: NSTitlebarAccessoryViewController {
+    private var sizeCancellable: AnyCancellable?
+
+    init(model: UpdateViewModel, onIdleTap: @escaping () -> Void) {
+        super.init(nibName: nil, bundle: nil)
+
+        let hostingView = NonDraggableHostingView(rootView: TitlebarAccessoryView(
+            model: model,
+            onIdleTap: onIdleTap
+        ))
+        hostingView.setFrameSize(hostingView.fittingSize)
+        view = hostingView
+
+        sizeCancellable = model.$state
+            .receive(on: DispatchQueue.main)
+            .sink { [weak hostingView] _ in
+                guard let hostingView else { return }
+                hostingView.invalidateIntrinsicContentSize()
+                hostingView.layoutSubtreeIfNeeded()
+                hostingView.setFrameSize(hostingView.fittingSize)
+            }
+    }
+
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+}
+
+final class UpdateTitlebarAccessoryController {
+    private weak var updateViewModel: UpdateViewModel?
+    private var didStart = false
+    private let attachedWindows = NSHashTable<NSWindow>.weakObjects()
+    private var observers: [NSObjectProtocol] = []
+
+    init(viewModel: UpdateViewModel) {
+        self.updateViewModel = viewModel
+    }
+
+    deinit {
+        for observer in observers {
+            NotificationCenter.default.removeObserver(observer)
+        }
+    }
+
+    func start() {
+        guard !didStart else { return }
+        didStart = true
+        attachToExistingWindows()
+        installObservers()
+    }
+
+    private func installObservers() {
+        let center = NotificationCenter.default
+        observers.append(center.addObserver(
+            forName: NSWindow.didBecomeMainNotification,
+            object: nil,
+            queue: .main
+        ) { [weak self] notification in
+            guard let window = notification.object as? NSWindow else { return }
+            self?.attachIfNeeded(to: window)
+        })
+
+        observers.append(center.addObserver(
+            forName: NSWindow.didBecomeKeyNotification,
+            object: nil,
+            queue: .main
+        ) { [weak self] notification in
+            guard let window = notification.object as? NSWindow else { return }
+            self?.attachIfNeeded(to: window)
+        })
+    }
+
+    private func attachToExistingWindows() {
+        for window in NSApp.windows {
+            attachIfNeeded(to: window)
+        }
+    }
+
+    private func attachIfNeeded(to window: NSWindow) {
+        guard let updateViewModel else { return }
+        guard !attachedWindows.contains(window) else { return }
+        guard window.styleMask.contains(.titled) else { return }
+
+        let identifier = NSUserInterfaceItemIdentifier("cmux.updateAccessory")
+        if window.titlebarAccessoryViewControllers.contains(where: { $0.view.identifier == identifier }) {
+            attachedWindows.add(window)
+            return
+        }
+
+        let accessory = UpdateAccessoryViewController(
+            model: updateViewModel,
+            onIdleTap: {
+                guard let delegate = NSApp.delegate as? AppDelegate else { return }
+                delegate.checkForUpdates(nil)
+            }
+        )
+        accessory.layoutAttribute = .right
+
+        accessory.view.identifier = identifier
+
+        window.addTitlebarAccessoryViewController(accessory)
+        attachedWindows.add(window)
+    }
+}

Sources/Update/UpdateViewModel.swift

@@ -0,0 +1,345 @@
+import Foundation
+import AppKit
+import SwiftUI
+import Sparkle
+
+class UpdateViewModel: ObservableObject {
+    @Published var state: UpdateState = .idle
+
+    var text: String {
+        switch state {
+        case .idle:
+            return ""
+        case .permissionRequest:
+            return "Enable Automatic Updates?"
+        case .checking:
+            return "Checking for Updates…"
+        case .updateAvailable(let update):
+            let version = update.appcastItem.displayVersionString
+            if !version.isEmpty {
+                return "Update Available: \(version)"
+            }
+            return "Update Available"
+        case .downloading(let download):
+            if let expectedLength = download.expectedLength, expectedLength > 0 {
+                let progress = Double(download.progress) / Double(expectedLength)
+                return String(format: "Downloading: %.0f%%", progress * 100)
+            }
+            return "Downloading…"
+        case .extracting(let extracting):
+            return String(format: "Preparing: %.0f%%", extracting.progress * 100)
+        case .installing(let install):
+            return install.isAutoUpdate ? "Restart to Complete Update" : "Installing…"
+        case .notFound:
+            return "No Updates Available"
+        case .error(let err):
+            return err.error.localizedDescription
+        }
+    }
+
+    var maxWidthText: String {
+        switch state {
+        case .downloading:
+            return "Downloading: 100%"
+        case .extracting:
+            return "Preparing: 100%"
+        default:
+            return text
+        }
+    }
+
+    var iconName: String? {
+        switch state {
+        case .idle:
+            return nil
+        case .permissionRequest:
+            return "questionmark.circle"
+        case .checking:
+            return "arrow.triangle.2.circlepath"
+        case .updateAvailable:
+            return "shippingbox.fill"
+        case .downloading:
+            return "arrow.down.circle"
+        case .extracting:
+            return "shippingbox"
+        case .installing:
+            return "power.circle"
+        case .notFound:
+            return "info.circle"
+        case .error:
+            return "exclamationmark.triangle.fill"
+        }
+    }
+
+    var description: String {
+        switch state {
+        case .idle:
+            return ""
+        case .permissionRequest:
+            return "Configure automatic update preferences"
+        case .checking:
+            return "Please wait while we check for available updates"
+        case .updateAvailable(let update):
+            return update.releaseNotes?.label ?? "Download and install the latest version"
+        case .downloading:
+            return "Downloading the update package"
+        case .extracting:
+            return "Extracting and preparing the update"
+        case let .installing(install):
+            return install.isAutoUpdate ? "Restart to Complete Update" : "Installing update and preparing to restart"
+        case .notFound:
+            return "You are running the latest version"
+        case .error:
+            return "An error occurred during the update process"
+        }
+    }
+
+    var badge: String? {
+        switch state {
+        case .updateAvailable(let update):
+            let version = update.appcastItem.displayVersionString
+            return version.isEmpty ? nil : version
+        case .downloading(let download):
+            if let expectedLength = download.expectedLength, expectedLength > 0 {
+                let percentage = Double(download.progress) / Double(expectedLength) * 100
+                return String(format: "%.0f%%", percentage)
+            }
+            return nil
+        case .extracting(let extracting):
+            return String(format: "%.0f%%", extracting.progress * 100)
+        default:
+            return nil
+        }
+    }
+
+    var iconColor: Color {
+        switch state {
+        case .idle:
+            return .secondary
+        case .permissionRequest:
+            return .white
+        case .checking:
+            return .secondary
+        case .updateAvailable:
+            return .accentColor
+        case .downloading, .extracting, .installing:
+            return .secondary
+        case .notFound:
+            return .secondary
+        case .error:
+            return .orange
+        }
+    }
+
+    var backgroundColor: Color {
+        switch state {
+        case .permissionRequest:
+            return Color(nsColor: NSColor.systemBlue.blended(withFraction: 0.3, of: .black) ?? .systemBlue)
+        case .updateAvailable:
+            return .accentColor
+        case .notFound:
+            return Color(nsColor: NSColor.systemBlue.blended(withFraction: 0.5, of: .black) ?? .systemBlue)
+        case .error:
+            return .orange.opacity(0.2)
+        default:
+            return Color(nsColor: .controlBackgroundColor)
+        }
+    }
+
+    var foregroundColor: Color {
+        switch state {
+        case .permissionRequest:
+            return .white
+        case .updateAvailable:
+            return .white
+        case .notFound:
+            return .white
+        case .error:
+            return .orange
+        default:
+            return .primary
+        }
+    }
+}
+
+enum UpdateState: Equatable {
+    case idle
+    case permissionRequest(PermissionRequest)
+    case checking(Checking)
+    case updateAvailable(UpdateAvailable)
+    case notFound(NotFound)
+    case error(Error)
+    case downloading(Downloading)
+    case extracting(Extracting)
+    case installing(Installing)
+
+    var isIdle: Bool {
+        if case .idle = self { return true }
+        return false
+    }
+
+    var isInstallable: Bool {
+        switch self {
+        case .checking,
+                .updateAvailable,
+                .downloading,
+                .extracting,
+                .installing:
+            return true
+        default:
+            return false
+        }
+    }
+
+    func cancel() {
+        switch self {
+        case .checking(let checking):
+            checking.cancel()
+        case .updateAvailable(let available):
+            available.reply(.dismiss)
+        case .downloading(let downloading):
+            downloading.cancel()
+        case .notFound(let notFound):
+            notFound.acknowledgement()
+        case .error(let err):
+            err.dismiss()
+        default:
+            break
+        }
+    }
+
+    func confirm() {
+        switch self {
+        case .updateAvailable(let available):
+            available.reply(.install)
+        default:
+            break
+        }
+    }
+
+    static func == (lhs: UpdateState, rhs: UpdateState) -> Bool {
+        switch (lhs, rhs) {
+        case (.idle, .idle):
+            return true
+        case (.permissionRequest, .permissionRequest):
+            return true
+        case (.checking, .checking):
+            return true
+        case (.updateAvailable(let lUpdate), .updateAvailable(let rUpdate)):
+            return lUpdate.appcastItem.displayVersionString == rUpdate.appcastItem.displayVersionString
+        case (.notFound, .notFound):
+            return true
+        case (.error(let lErr), .error(let rErr)):
+            return lErr.error.localizedDescription == rErr.error.localizedDescription
+        case (.downloading(let lDown), .downloading(let rDown)):
+            return lDown.progress == rDown.progress && lDown.expectedLength == rDown.expectedLength
+        case (.extracting(let lExt), .extracting(let rExt)):
+            return lExt.progress == rExt.progress
+        case (.installing(let lInstall), .installing(let rInstall)):
+            return lInstall.isAutoUpdate == rInstall.isAutoUpdate
+        default:
+            return false
+        }
+    }
+
+    struct NotFound {
+        let acknowledgement: () -> Void
+    }
+
+    struct PermissionRequest {
+        let request: SPUUpdatePermissionRequest
+        let reply: @Sendable (SUUpdatePermissionResponse) -> Void
+    }
+
+    struct Checking {
+        let cancel: () -> Void
+    }
+
+    struct UpdateAvailable {
+        let appcastItem: SUAppcastItem
+        let reply: @Sendable (SPUUserUpdateChoice) -> Void
+
+        var releaseNotes: ReleaseNotes? {
+            ReleaseNotes(displayVersionString: appcastItem.displayVersionString)
+        }
+    }
+
+    enum ReleaseNotes {
+        case commit(URL)
+        case tagged(URL)
+
+        init?(displayVersionString: String) {
+            let version = displayVersionString
+
+            if let semver = Self.extractSemanticVersion(from: version) {
+                let tag = semver.hasPrefix("v") ? semver : "v\(semver)"
+                if let url = URL(string: "https://github.com/manaflow-ai/GhosttyTabs/releases/tag/\(tag)") {
+                    self = .tagged(url)
+                    return
+                }
+            }
+
+            guard let newHash = Self.extractGitHash(from: version) else {
+                return nil
+            }
+
+            if let url = URL(string: "https://github.com/manaflow-ai/GhosttyTabs/commit/\(newHash)") {
+                self = .commit(url)
+            } else {
+                return nil
+            }
+        }
+
+        private static func extractSemanticVersion(from version: String) -> String? {
+            let pattern = #"v?\d+\.\d+\.\d+"#
+            if let range = version.range(of: pattern, options: .regularExpression) {
+                return String(version[range])
+            }
+            return nil
+        }
+
+        private static func extractGitHash(from version: String) -> String? {
+            let pattern = #"[0-9a-f]{7,40}"#
+            if let range = version.range(of: pattern, options: .regularExpression) {
+                return String(version[range])
+            }
+            return nil
+        }
+
+        var url: URL {
+            switch self {
+            case .commit(let url): return url
+            case .tagged(let url): return url
+            }
+        }
+
+        var label: String {
+            switch self {
+            case .commit: return "View GitHub Commit"
+            case .tagged: return "View Release Notes"
+            }
+        }
+    }
+
+    struct Error {
+        let error: any Swift.Error
+        let retry: () -> Void
+        let dismiss: () -> Void
+    }
+
+    struct Downloading {
+        let cancel: () -> Void
+        let expectedLength: UInt64?
+        let progress: UInt64
+    }
+
+    struct Extracting {
+        let progress: Double
+    }
+
+    struct Installing {
+        var isAutoUpdate = false
+        let retryTerminatingApplication: () -> Void
+        let dismiss: () -> Void
+    }
+}

Sources/WindowToolbarController.swift

@@ -0,0 +1,135 @@
+import AppKit
+import SwiftUI
+
+final class WindowToolbarController: NSObject, NSToolbarDelegate {
+    private let commandItemIdentifier = NSToolbarItem.Identifier("cmux.focusedCommand")
+    private let updateItemIdentifier = NSToolbarItem.Identifier("cmux.updatePill")
+
+    private weak var tabManager: TabManager?
+    private weak var updateViewModel: UpdateViewModel?
+
+    private var commandLabels: [ObjectIdentifier: NSTextField] = [:]
+    private var observers: [NSObjectProtocol] = []
+
+    init(updateViewModel: UpdateViewModel) {
+        self.updateViewModel = updateViewModel
+        super.init()
+    }
+
+    deinit {
+        for observer in observers {
+            NotificationCenter.default.removeObserver(observer)
+        }
+    }
+
+    func start(tabManager: TabManager) {
+        self.tabManager = tabManager
+        attachToExistingWindows()
+        installObservers()
+        updateFocusedCommandText()
+    }
+
+    private func installObservers() {
+        let center = NotificationCenter.default
+        observers.append(center.addObserver(
+            forName: .ghosttyDidSetTitle,
+            object: nil,
+            queue: .main
+        ) { [weak self] _ in
+            self?.updateFocusedCommandText()
+        })
+
+        observers.append(center.addObserver(
+            forName: .ghosttyDidFocusTab,
+            object: nil,
+            queue: .main
+        ) { [weak self] _ in
+            self?.updateFocusedCommandText()
+        })
+
+        observers.append(center.addObserver(
+            forName: NSWindow.didBecomeMainNotification,
+            object: nil,
+            queue: .main
+        ) { [weak self] notification in
+            guard let window = notification.object as? NSWindow else { return }
+            self?.attach(to: window)
+        })
+    }
+
+    private func attachToExistingWindows() {
+        for window in NSApp.windows {
+            attach(to: window)
+        }
+    }
+
+    private func attach(to window: NSWindow) {
+        guard window.toolbar == nil else { return }
+        let toolbar = NSToolbar(identifier: NSToolbar.Identifier("cmux.toolbar"))
+        toolbar.delegate = self
+        toolbar.displayMode = .iconOnly
+        toolbar.allowsUserCustomization = false
+        toolbar.autosavesConfiguration = false
+        toolbar.showsBaselineSeparator = false
+        window.toolbar = toolbar
+        window.toolbarStyle = .unified
+        window.titleVisibility = .visible
+    }
+
+    private func updateFocusedCommandText() {
+        guard let tabManager else { return }
+        let text: String
+        if let selectedId = tabManager.selectedTabId,
+           let tab = tabManager.tabs.first(where: { $0.id == selectedId }) {
+            let title = tab.title.trimmingCharacters(in: .whitespacesAndNewlines)
+            text = title.isEmpty ? "Cmd: —" : "Cmd: \(title)"
+        } else {
+            text = "Cmd: —"
+        }
+
+        for label in commandLabels.values {
+            label.stringValue = text
+        }
+    }
+
+    // MARK: - NSToolbarDelegate
+
+    func toolbarAllowedItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] {
+        [commandItemIdentifier, .flexibleSpace, updateItemIdentifier]
+    }
+
+    func toolbarDefaultItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] {
+        [commandItemIdentifier, .flexibleSpace, updateItemIdentifier]
+    }
+
+    func toolbar(_ toolbar: NSToolbar, itemForItemIdentifier itemIdentifier: NSToolbarItem.Identifier, willBeInsertedIntoToolbar flag: Bool) -> NSToolbarItem? {
+        if itemIdentifier == commandItemIdentifier {
+            let item = NSToolbarItem(itemIdentifier: itemIdentifier)
+            let label = NSTextField(labelWithString: "Cmd: —")
+            label.font = NSFont.systemFont(ofSize: 12, weight: .medium)
+            label.textColor = .secondaryLabelColor
+            label.lineBreakMode = .byTruncatingMiddle
+            label.setContentHuggingPriority(.defaultHigh, for: .horizontal)
+            item.view = label
+            commandLabels[ObjectIdentifier(toolbar)] = label
+            updateFocusedCommandText()
+            return item
+        }
+
+        if itemIdentifier == updateItemIdentifier, let updateViewModel {
+            let item = NSToolbarItem(itemIdentifier: itemIdentifier)
+            let view = NonDraggableHostingView(rootView: UpdatePill(
+                model: updateViewModel,
+                showWhenIdle: true,
+                onIdleTap: {
+                    guard let delegate = NSApp.delegate as? AppDelegate else { return }
+                    delegate.checkForUpdates(nil)
+                }
+            ))
+            item.view = view
+            return item
+        }
+
+        return nil
+    }
+}

Sources/cmuxApp.swift

@@ -14,7 +14,7 @@ struct cmuxApp: App {
 
     var body: some Scene {
         WindowGroup {
-            ContentView()
+            ContentView(updateViewModel: appDelegate.updateViewModel)
                 .environmentObject(tabManager)
                 .environmentObject(notificationStore)
                 .onAppear {
@@ -23,7 +23,7 @@ struct cmuxApp: App {
                     appDelegate.configure(tabManager: tabManager, notificationStore: notificationStore)
                 }
         }
-        .windowStyle(.hiddenTitleBar)
+        .windowToolbarStyle(.automatic)
         .commands {
             CommandGroup(replacing: .appInfo) {
                 Button("About cmux") {
@@ -31,6 +31,12 @@ struct cmuxApp: App {
                 }
             }
 
+            CommandGroup(after: .appInfo) {
+                Button("Check for Updates…") {
+                    appDelegate.checkForUpdates(nil)
+                }
+            }
+
             // New tab commands
             CommandGroup(replacing: .newItem) {
                 Button("New Tab") {

scripts/sparkle_generate_appcast.sh

@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [[ $# -lt 2 ]]; then
+  echo "Usage: $0 <dmg-path> <tag> [output-path]" >&2
+  exit 1
+fi
+
+DMG_PATH="$1"
+TAG="$2"
+OUT_PATH="${3:-appcast.xml}"
+
+if [[ -z "${SPARKLE_PRIVATE_KEY:-}" ]]; then
+  echo "SPARKLE_PRIVATE_KEY is required (exported from Sparkle generate_keys)." >&2
+  exit 1
+fi
+
+SPARKLE_VERSION="${SPARKLE_VERSION:-2.8.1}"
+DOWNLOAD_URL_PREFIX="${DOWNLOAD_URL_PREFIX:-https://github.com/manaflow-ai/GhosttyTabs/releases/download/$TAG/}"
+RELEASE_NOTES_URL="${RELEASE_NOTES_URL:-https://github.com/manaflow-ai/GhosttyTabs/releases/tag/$TAG}"
+
+work_dir="$(mktemp -d)"
+cleanup() {
+  rm -rf "$work_dir"
+}
+trap cleanup EXIT
+
+echo "Cloning Sparkle ${SPARKLE_VERSION}..."
+git clone --depth 1 --branch "$SPARKLE_VERSION" https://github.com/sparkle-project/Sparkle "$work_dir/Sparkle"
+
+echo "Building Sparkle generate_appcast tool..."
+xcodebuild \
+  -project "$work_dir/Sparkle/Sparkle.xcodeproj" \
+  -scheme generate_appcast \
+  -configuration Release \
+  -derivedDataPath "$work_dir/build" \
+  CODE_SIGNING_ALLOWED=NO \
+  build >/dev/null
+
+generate_appcast="$work_dir/build/Build/Products/Release/generate_appcast"
+if [[ ! -x "$generate_appcast" ]]; then
+  echo "generate_appcast binary not found at $generate_appcast" >&2
+  exit 1
+fi
+
+archives_dir="$work_dir/archives"
+mkdir -p "$archives_dir"
+cp "$DMG_PATH" "$archives_dir/$(basename "$DMG_PATH")"
+
+printf "%s" "$SPARKLE_PRIVATE_KEY" | "$generate_appcast" \
+  --ed-key-file - \
+  --download-url-prefix "$DOWNLOAD_URL_PREFIX" \
+  --full-release-notes-url "$RELEASE_NOTES_URL" \
+  "$archives_dir"
+
+if [[ ! -f "$archives_dir/appcast.xml" ]]; then
+  echo "appcast.xml not generated." >&2
+  exit 1
+fi
+
+cp "$archives_dir/appcast.xml" "$OUT_PATH"
+echo "Generated appcast at $OUT_PATH"

scripts/sparkle_generate_keys.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SPARKLE_VERSION="${SPARKLE_VERSION:-2.8.1}"
+SPARKLE_KEYCHAIN_ACCOUNT="${SPARKLE_KEYCHAIN_ACCOUNT:-cmux}"
+SPARKLE_ENV_FILE="${SPARKLE_ENV_FILE:-.env}"
+
+work_dir="$(mktemp -d)"
+cleanup() {
+  rm -rf "$work_dir"
+}
+trap cleanup EXIT
+
+echo "Cloning Sparkle ${SPARKLE_VERSION}..."
+git clone --depth 1 --branch "$SPARKLE_VERSION" https://github.com/sparkle-project/Sparkle "$work_dir/Sparkle"
+
+echo "Building Sparkle generate_keys tool..."
+xcodebuild \
+  -project "$work_dir/Sparkle/Sparkle.xcodeproj" \
+  -scheme generate_keys \
+  -configuration Release \
+  -derivedDataPath "$work_dir/build" \
+  CODE_SIGNING_ALLOWED=NO \
+  build >/dev/null
+
+generate_keys="$work_dir/build/Build/Products/Release/generate_keys"
+if [[ ! -x "$generate_keys" ]]; then
+  echo "generate_keys binary not found at $generate_keys" >&2
+  exit 1
+fi
+
+echo "Generating or locating Sparkle keys in keychain (account: $SPARKLE_KEYCHAIN_ACCOUNT)..."
+"$generate_keys" --account "$SPARKLE_KEYCHAIN_ACCOUNT"
+
+public_key="$("$generate_keys" --account "$SPARKLE_KEYCHAIN_ACCOUNT" -p)"
+private_key_file="$work_dir/sparkle_private_key.txt"
+"$generate_keys" --account "$SPARKLE_KEYCHAIN_ACCOUNT" -x "$private_key_file"
+private_key="$(cat "$private_key_file")"
+
+if [[ -z "$public_key" || -z "$private_key" ]]; then
+  echo "Failed to generate Sparkle keys." >&2
+  exit 1
+fi
+
+if [[ -f "$SPARKLE_ENV_FILE" ]]; then
+  tmp_env="$work_dir/env.tmp"
+  awk -F= 'BEGIN {OFS="="}
+    $1 == "SPARKLE_PUBLIC_KEY" {next}
+    $1 == "SPARKLE_PRIVATE_KEY" {next}
+    {print}
+  ' "$SPARKLE_ENV_FILE" > "$tmp_env"
+  mv "$tmp_env" "$SPARKLE_ENV_FILE"
+fi
+
+{
+  echo "SPARKLE_PUBLIC_KEY=$public_key"
+  echo "SPARKLE_PRIVATE_KEY=$private_key"
+} >> "$SPARKLE_ENV_FILE"
+
+echo "Sparkle keys written to $SPARKLE_ENV_FILE"