Transcription text stream not received in client despite text_enabled=True

[axodevjs]

I'm building a custom voice agent using the LiveKit Agents Python SDK. Audio and TTS work correctly, but transcription events are not being received on the frontend client (listening to "lk.transcription" stream). I'm setting text_enabled=True, but no text events arrive.

Environment:

• livekit-agents version: 1.0.0
• Backend language: Python
• Frontend: React Native with @livekit/react-native v2.7.4
• STT: Deepgram
• LLM: OpenAI
• TTS: Cartesia
• VAD: Silero

Backend code (simplified):

from livekit.agents import JobContext, WorkerOptions, cli
from livekit.agents.voice import Agent, AgentSession
from livekit.plugins import silero, deepgram, openai, cartesia

class MyAgent(Agent):
    def __init__(self, instructions, vad_model):
        super().__init__(
            instructions=instructions,
            stt=deepgram.STT(),
            llm=openai.LLM(model="gpt-4o-mini-2024-07-18"),
            tts=cartesia.TTS(model="sonic", sample_rate=44100),
            vad=vad_model,
            text_enabled=True  # Explicitly enabling text
        )

async def entrypoint(ctx: JobContext):
    await ctx.connect()
    await ctx.wait_for_participant()
    vad = await silero.VAD.load()
    agent = MyAgent("You are a helpful assistant.", vad_model=vad)
    session = AgentSession()
    await session.start(agent=agent, room=ctx.room)
    await session.say("Hello! I am ready.")
Frontend code (React Native):

tsx
// In Messages component
useEffect(() => {
  if (!room || room.state !== "connected") return;

  console.log("✅ Room connected, registering text stream handler");

  room.registerTextStreamHandler(
    "lk.transcription",
    async (reader, participantInfo) => {
      const msg = await reader.readAll();
      console.log("📩 transcription:", msg);
      
      // Add message to UI
      addMessage({
        text: msg,
        isLocalParticipant: false,
      });
    }
  );
}, [room?.state]);
Issues:

Audio and responses from the agent work fine
No lk.transcription events are received
No logs or errors shown in agent or frontend

[longcw]

did you follow the the document in https://docs.livekit.io/agents/build/text/#frontend-integration?

you can also verify if the transcription sent to lk.transcription text stream using this example to join the same room of the agent

python  chat-stream-receiver.py room-id

[axodevjs]

I've tested your suggested approach with the Python chat-stream-receiver.py script, and it confirms that transcriptions are being sent to the room on the "lk.transcription" topic. However, my React Native client is not receiving these messages despite having the handler properly registered. The room connects successfully, but no transcription events are received.
Library versions:

• livekit-client: 2.13.5
• @livekit/react-native: 2.7.4

Handler code:

// In Messages component
useEffect(() => {
  if (!room) return;
  
  const TRANSCRIPTION_TOPIC = "lk.transcription";
  
  try {
    room.registerTextStreamHandler(TRANSCRIPTION_TOPIC, async (reader, participantInfo) => {
      console.log("🚀 [TEXT STREAM] Got a message from", participantInfo.identity);
      const message = await reader.readAll();
      console.log("📩 Message content:", message);
      
      addMessage({
        text: message,
        isLocalParticipant: false,
      });
      
      scrollToEnd();
    });
    
    console.log("Handler registered successfully");
  } catch (error) {
    console.error("Error registering handler:", error);
  }
  
  return () => {
    // Cleanup
    room.removeAllListeners();
  };
}, [room]);```
The room connects successfully, but no transcription events are received. I've followed the documentation at https://docs.livekit.io/agents/build/text/#frontend-integration
 Otherwise, legacy method is working well

[longcw]

@lukasIO can you help to take a look

[lukasIO]

hi @axodevjs,

there are some related issues on the react-native repo, could you try this workaround?

[axodevjs]

@lukasIO Unfortunately, this solution did not work for me. I'm still not receiving any transcription events in my React Native client, even though I've confirmed with the Python chat-stream-receiver.py script that transcriptions are being sent to the room.

Any other suggestions or potential fixes would be greatly appreciated.

[lukasIO]

please post the full logs for further investigation

[axodevjs]

@lukasIO I've implemented the suggested workaround with WritableStream polyfill and confirmed that the handler is properly registered:

---

1. Added polyfills:

// src/polyfills.ts
import { WritableStream } from 'web-streams-polyfill';

if (typeof global.WritableStream === 'undefined') {
  // @ts-ignore
  global.WritableStream = WritableStream;
}

---

2. Imported at app entry point:

// App.tsx
import "@/polyfills";

---

3. Registered handler correctly:

room.registerTextStreamHandler(
  "lk.transcription",
  async (reader, participantInfo) => {
    const message = await reader.readAll();
    console.log("Received transcription:", message);
    // ...rest of handler
  }
);

---

4. Logs confirm successful registration:

LOG  Registering lk.transcription handler  
LOG  Room connected, handler registered

---

5. Room connects successfully and audio works, but no transcription events are received.

6. Python chat-stream-receiver.py confirms transcriptions are being sent to the room.

Environment:
React Native 0.74.5
@livekit/react-native: 2.7.4
livekit-client: 2.13.5
web-streams-polyfill: 4.1.0

[davidliu]

@axodevjs It looks like there was a separate issue with the Symbol.asyncIterator shim ordering that didn't work with the data streams.

I've included the required polyfills and fixes in this PR: #247

[axodevjs]

Thanks!!

[davidliu]

Fix released in v2.7.5