fix: deduplicate desktop notifications and tighten notification text extraction

Desktop notifications no longer duplicate when native delivery succeeds
Reasoning chain-of-thought is excluded from notification body text
Untyped message parts are ignored in notification text extraction

packages/ui/src/sync/sync-context.tsx

@@ -326,11 +326,12 @@ type UiNotificationPayload = {
   body?: unknown
   tag?: unknown
   kind?: unknown
-  sessionId?: unknown
-  directory?: unknown
-  requireHidden?: unknown
-  desktopStdoutActive?: unknown
-}
+  sessionId?: unknown
+  directory?: unknown
+  requireHidden?: unknown
+  desktopNotificationDelivered?: unknown
+  desktopStdoutActive?: unknown
+}
 
 const asOptionalString = (value: unknown): string | undefined => {
   if (typeof value !== "string") return undefined
@@ -349,9 +350,9 @@ const handleUiNotificationEvent = (payload: Event, fallbackDirectory: string): b
   }
 
   const notification = properties as UiNotificationPayload
-  if (notification.desktopStdoutActive === true && getRuntimeKey() === "local") {
-    return true
-  }
+  if ((notification.desktopNotificationDelivered === true || notification.desktopStdoutActive === true) && getRuntimeKey() === "local") {
+    return true
+  }
 
   const notifications = getRegisteredRuntimeAPIs()?.notifications
   if (!notifications?.notifyAgentCompletion) {