diff --git a/clients/macos/vellum-assistant/App/AppDelegate+AuthLifecycle.swift b/clients/macos/vellum-assistant/App/AppDelegate+AuthLifecycle.swift
index 4baff760057..44bba6c72c0 100644
--- a/clients/macos/vellum-assistant/App/AppDelegate+AuthLifecycle.swift
+++ b/clients/macos/vellum-assistant/App/AppDelegate+AuthLifecycle.swift
@@ -144,8 +144,16 @@ extension AppDelegate {
     }
 
     @objc func performRestart() {
+        isRestarting = true
         let bundleURL = Bundle.main.bundleURL
 
+        // Disconnect SSE and health checks *before* the CLI kills the
+        // daemon/gateway.  Otherwise the health check detects the daemon
+        // dying, triggers autoWakeIfAssistantDied(), and wakes the daemon
+        // right back up — fighting with the shutdown.  (Same pattern as
+        // performRetireAsync().)
+        connectionManager.disconnect()
+
         // Write a timestamped sentinel so the new instance's single-instance
         // guard knows this is an intentional restart, not a duplicate launch.
         // The sentinel contains the current Unix timestamp; the new instance
@@ -165,6 +173,13 @@ extension AppDelegate {
                 // Clean up the sentinel so a failed restart doesn't leave
                 // a file that could bypass the guard on the next launch.
                 try? FileManager.default.removeItem(at: sentinelPath)
+                self?.isRestarting = false
+                // Reconnect SSE and health checks so the app doesn't stay
+                // in a disconnected state after a failed relaunch attempt.
+                // (Same pattern as performRetireAsync()'s cancel path.)
+                Task { @MainActor [weak self] in
+                    try? await self?.connectionManager.connect()
+                }
                 return
             }
             Task { @MainActor [weak self] in
diff --git a/clients/macos/vellum-assistant/App/AppDelegate.swift b/clients/macos/vellum-assistant/App/AppDelegate.swift
index 8165d236e73..2f0756b72a6 100644
--- a/clients/macos/vellum-assistant/App/AppDelegate.swift
+++ b/clients/macos/vellum-assistant/App/AppDelegate.swift
@@ -38,6 +38,7 @@ public final class AppDelegate: NSObject, NSApplicationDelegate {
     var lastRegisteredQuickInputHotkey: String?
     var globalHotkeyObserver: AnyCancellable?
     var escapeMonitor: Any?
+    var isRestarting = false
     var hasSetupHotKey = false
     var fnVGlobalMonitor: Any?
     var fnVLocalMonitor: Any?
@@ -745,6 +746,14 @@ public final class AppDelegate: NSObject, NSApplicationDelegate {
     ///
     /// Reference: https://developer.apple.com/documentation/appkit/nsapplicationdelegate/applicationshouldterminate(_:)
     public func applicationShouldTerminate(_ sender: NSApplication) -> NSApplication.TerminateReply {
+        // During a restart, performRestart() already stopped the CLI and
+        // disconnected the connection manager.  Skip the async
+        // .terminateLater path whose MainActor.run dispatch is fragile
+        // during AppKit shutdown and can leave the process as a zombie.
+        if isRestarting {
+            return .terminateNow
+        }
+
         let cli = vellumCli
         Task.detached {
             await cli.stop()