In LiveKit, the agent worker is automatically removed when the callee ends the call due to the session closure. To trigger a webhook with the call session ID upon call hangup, you can implement a session close callback that captures the session close event, extracts the session ID, and sends a POST request to your webhook endpoint. Here is an example approach in Python:

import asyncio
import logging
from livekit.agents import Agent, AgentSession, CloseEvent, JobContext, WorkerOptions, cli

logger = logging.getLogger("my-worker")
logger.setLevel(<http://logging.INFO|logging.INFO>)

class MyAgent(Agent):
    def __init__(self):
        super().__init__(instructions="You are a helpful assistant.")

async def on_session_close(event: CloseEvent):
    session_id = event.session.id
    <http://logger.info|logger.info>(f"Session {session_id} closed, reason: {event.reason}")
    
    # Trigger webhook here
    async def trigger_webhook(session_id):
        try:
            webhook_url = "<https://your-webhook-url.com/hangup>"
            data = {"session_id": session_id, "event": "hangup"}
            headers = {"Content-Type": "application/json"}
            await <http://httpx.post|httpx.post>(webhook_url, json=data, headers=headers)
        except Exception as e:
            logger.error(f"Failed to trigger webhook: {e}")

    await trigger_webhook(session_id)

async def entrypoint(ctx: JobContext):
    session = AgentSession()
    
    @session.on("close")
    def handle_close(event: CloseEvent):
        asyncio.create_task(on_session_close(event))
        
    await session.start(agent=MyAgent(), room=ctx.room)
    await ctx.connect()

if __name__ == "__main__":
    cli.run_app(WorkerOptions(entrypoint_fnc=entrypoint))

This setup ensures that when the call ends, the agent worker is removed automatically, and your webhook gets notified with the call session ID and hangup event. Remember to handle authentication and failure cases in your webhook implementation. Sources: .github/next-release/changeset-12012403.md