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/web/server/lib/notifications/emitter-runtime.js

@@ -29,43 +29,51 @@ export const createNotificationEmitterRuntime = (dependencies) => {
   const emitDesktopNotification = (payload) => {
     const desktopNotifyEnabled = getDesktopNotifyEnabled();
     if (!desktopNotifyEnabled) {
-      return;
+      return false;
     }
 
     if (!payload || typeof payload !== 'object') {
-      return;
+      return false;
     }
 
     if (onDesktopNotification) {
       try {
         onDesktopNotification(payload);
+        return true;
       } catch {
         // ignore host-side throw
       }
-      return;
+      return false;
     }
 
     try {
       // stdout fallback for runtimes that parse the one-line `${prefix}{json}` protocol.
       process.stdout.write(`${desktopNotifyPrefix}${JSON.stringify(payload)}\n`);
+      return true;
     } catch {
       // ignore
     }
+
+    return false;
   };
 
-  const broadcastUiNotification = (payload) => {
+  const broadcastUiNotification = (payload, options = {}) => {
     const desktopNotifyEnabled = getDesktopNotifyEnabled();
     if (!payload || typeof payload !== 'object') {
       return;
     }
 
+    const desktopNotificationDelivered = options.desktopNotificationDelivered === true;
+
     const syntheticPayload = {
       type: 'openchamber:notification',
       properties: {
         ...payload,
-        // Tell the UI whether the stdout notification channel is active.
-        // When true, the desktop UI should skip this SSE notification to avoid duplicates.
-        // When false, the UI must handle this SSE notification itself.
+        // Tell local desktop UI whether a native channel already accepted this
+        // notification. If so, the SSE/WS event is informational only and must
+        // not create a second OS notification.
+        desktopNotificationDelivered,
+        // Legacy marker retained for older clients that only know about stdout.
         desktopStdoutActive: desktopNotifyEnabled,
       },
     };