label_messages

title	category	tags	difficulty	description	demonstrates
Conversation Event Monitoring Agent	basics	events conversation-monitoring logging deepgram openai	beginner	Shows how to monitor and log conversation events as they occur, useful for debugging and understanding agent-user interactions.	Conversation event handling and logging

In this recipe you will subscribe to conversation events and print them as they occur. It is a quick way to debug how the session labels transcripts, responses, and tool calls.

Prerequisites

• Add a .env in this directory with your LiveKit credentials:

  LIVEKIT_URL=your_livekit_url
  LIVEKIT_API_KEY=your_api_key
  LIVEKIT_API_SECRET=your_api_secret
  

• Install dependencies:

  pip install "livekit-agents[silero]" python-dotenv

Load configuration and logging

Load environment variables and configure logging.

import logging
from dotenv import load_dotenv
from livekit.agents import JobContext, JobProcess, cli, Agent, AgentSession, AgentServer, inference, ConversationItemAddedEvent
from livekit.plugins import silero

load_dotenv()

logger = logging.getLogger("label-messages")
logger.setLevel(logging.INFO)

server = AgentServer()

Prewarm VAD and Define Entrypoint

We preload the VAD model to improve latency. Inside the rtc_session, we configure the AgentSession with STT, LLM, TTS, and the preloaded VAD.

def prewarm(proc: JobProcess):
    proc.userdata["vad"] = silero.VAD.load()

server.setup_fnc = prewarm

@server.rtc_session()
async def entrypoint(ctx: JobContext):
    session = AgentSession(
        stt=inference.STT(model="deepgram/nova-3-general"),
        llm=inference.LLM(model="openai/gpt-4.1-mini"),
        tts=inference.TTS(model="cartesia/sonic-3", voice="9626c31c-bec5-4cca-baa8-f8ba9e84c8bc"),
        vad=ctx.proc.userdata["vad"],
    )

    agent = Agent(
        instructions="You are a helpful agent. When the user speaks, you listen and respond.",
    )
    # ...

Subscribe to conversation events

Listen for conversation_item_added and print each event so you can observe the labeled items flowing through the session.

    @session.on("conversation_item_added")
    def conversation_item_added(item: ConversationItemAddedEvent):
        print(item)

Start the session

Connect and start the agent; event logs will appear as the conversation progresses.

    @session.on("session_start")
    def on_session_start():
        session.generate_reply()

    await session.start(agent=agent, room=ctx.room)
    await ctx.connect()

if __name__ == "__main__":
    cli.run_app(server)

Run it

python label_messages.py console

How it works

• The agent runs with a standard voice stack.
• A session-level listener prints every conversation_item_added event.
• You can watch how transcripts, replies, and tool calls are labeled in real time.

Full example

import logging
from dotenv import load_dotenv
from livekit.agents import JobContext, JobProcess, cli, Agent, AgentSession, AgentServer, inference, ConversationItemAddedEvent
from livekit.plugins import silero

load_dotenv()

logger = logging.getLogger("label-messages")
logger.setLevel(logging.INFO)

server = AgentServer()

def prewarm(proc: JobProcess):
    proc.userdata["vad"] = silero.VAD.load()

server.setup_fnc = prewarm

@server.rtc_session()
async def entrypoint(ctx: JobContext):
    session = AgentSession(
        stt=inference.STT(model="deepgram/nova-3-general"),
        llm=inference.LLM(model="openai/gpt-4.1-mini"),
        tts=inference.TTS(model="cartesia/sonic-3", voice="9626c31c-bec5-4cca-baa8-f8ba9e84c8bc"),
        vad=ctx.proc.userdata["vad"],
    )

    agent = Agent(
        instructions="You are a helpful agent. When the user speaks, you listen and respond.",
    )

    @session.on("conversation_item_added")
    def conversation_item_added(item: ConversationItemAddedEvent):
        print(item)

    @session.on("session_start")
    def on_session_start():
        session.generate_reply()

    await session.start(agent=agent, room=ctx.room)
    await ctx.connect()

if __name__ == "__main__":
    cli.run_app(server)