Add optional service field to ServiceUpdateSettingsFrame for targeting a specific service instance

When `service` is set and doesn't match, the service forwards the frame instead of consuming it. This allows targeting a specific service when multiple services of the same type exist in the pipeline.

src/pipecat/frames/frames.py

@@ -2154,10 +2154,15 @@ class ServiceUpdateSettingsFrame(ControlFrame, UninterruptibleFrame):
 
         delta: :class:`~pipecat.services.settings.ServiceSettings` delta-mode
             object describing the fields to change.
+
+        service: Optional target service instance. When provided, only that
+            service will apply the settings; other services will forward the
+            frame unchanged.
     """
 
     settings: Mapping[str, Any] = field(default_factory=dict)
     delta: Optional["ServiceSettings"] = None
+    service: Optional["FrameProcessor"] = None
 
 
 @dataclass

src/pipecat/services/llm_service.py

@@ -403,7 +403,9 @@ class LLMService(UserTurnCompletionLLMServiceMixin, AIService):
         elif isinstance(frame, LLMConfigureOutputFrame):
             self._skip_tts = frame.skip_tts
         elif isinstance(frame, LLMUpdateSettingsFrame):
-            if frame.delta is not None:
+            if frame.service is not None and frame.service is not self:
+                await self.push_frame(frame, direction)
+            elif frame.delta is not None:
                 await self._update_settings(frame.delta)
             elif frame.settings:
                 # Backward-compatible path: convert legacy dict to settings object.

src/pipecat/services/openai_realtime_beta/openai.py

@@ -386,7 +386,11 @@ class OpenAIRealtimeBetaLLMService(LLMService):
         # fields, not our Settings fields, so we construct SessionProperties
         # directly. The frame.delta path falls through to super, which calls
         # _update_settings → our override handles the rest.
-        if isinstance(frame, LLMUpdateSettingsFrame) and frame.delta is None:
+        if (
+            isinstance(frame, LLMUpdateSettingsFrame)
+            and frame.delta is None
+            and (frame.service is None or frame.service is self)
+        ):
             self._session_properties = events.SessionProperties(**frame.settings)
             await self._send_session_update()
             await self.push_frame(frame, direction)

src/pipecat/services/stt_service.py

@@ -357,7 +357,9 @@ class STTService(AIService):
             await self._handle_vad_user_stopped_speaking(frame)
             await self.push_frame(frame, direction)
         elif isinstance(frame, STTUpdateSettingsFrame):
-            if frame.delta is not None:
+            if frame.service is not None and frame.service is not self:
+                await self.push_frame(frame, direction)
+            elif frame.delta is not None:
                 await self._update_settings(frame.delta)
             elif frame.settings:
                 # Backward-compatible path: convert legacy dict to settings object.

src/pipecat/services/tts_service.py

@@ -738,7 +738,9 @@ class TTSService(AIService):
             self._turn_context_id = saved_turn_context_id
             self._processing_text = processing_text
         elif isinstance(frame, TTSUpdateSettingsFrame):
-            if frame.delta is not None:
+            if frame.service is not None and frame.service is not self:
+                await self.push_frame(frame, direction)
+            elif frame.delta is not None:
                 await self._update_settings(frame.delta)
             elif frame.settings:
                 # Backward-compatible path: convert legacy dict to settings object.