fix FCM push notifications

gateway-plugin/http_server.py

@@ -275,6 +275,13 @@ class HttpServer:
     def _add_sub(self, sub: _Subscriber) -> None:
         with self._subs_lock:
             self._subs.setdefault(sub.device_id, []).append(sub)
+        # M5: a live subscriber will sync the outbox -- tell the adapter to
+        # drop any held-back (deferred) pushes so the turn-end flush doesn't
+        # duplicate what the app already shows. getattr-guard: test doubles
+        # may use a bare adapter stub.
+        on_online = getattr(self._adapter, "on_device_online", None)
+        if on_online is not None:
+            on_online()
 
     def _remove_sub(self, sub: _Subscriber) -> None:
         with self._subs_lock: