Fix "bot-llm-text" not firing when using OpenAI Realtime

src/pipecat/services/openai/realtime/llm.py

@@ -724,10 +724,26 @@ class OpenAIRealtimeLLMService(LLMService):
         # We receive audio transcript deltas (as opposed to text deltas) when
         # the output modality is "audio" (the default)
         if evt.delta:
-            frame = TTSTextFrame(evt.delta, aggregated_by=AggregationType.SENTENCE)
-            # OpenAI Realtime text already includes any necessary inter-chunk spaces
-            frame.includes_inter_frame_spaces = True
-            await self.push_frame(frame)
+            await self._push_output_transcript_text_frames(evt.delta)
+
+    async def _push_output_transcript_text_frames(self, text: str):
+        # In a typical "cascade" LLM + TTS setup, LLMTextFrames would not
+        # proceed beyond the TTS service. Therefore, since a speech-to-speech
+        # service like OpenAI Realtime combines both LLM and TTS functionality,
+        # you might think we wouldn't need to push LLMTextFrames at all.
+        # However, RTVI relies on LLMTextFrames being pushed to trigger its
+        # "bot-llm-text" event. So here we push an LLMTextFrame, too, but avoid
+        # appending it to context to avoid context message duplication.
+
+        # Push LLMTextFrame
+        llm_text_frame = LLMTextFrame(text)
+        llm_text_frame.append_to_context = False
+        await self.push_frame(llm_text_frame)
+
+        # Push TTSTextFrame
+        tts_text_frame = TTSTextFrame(text, aggregated_by=AggregationType.SENTENCE)
+        tts_text_frame.includes_inter_frame_spaces = True
+        await self.push_frame(tts_text_frame)
 
     async def _handle_evt_function_call_arguments_done(self, evt):
         """Handle completion of function call arguments.