multi_agent.ts

// SPDX-FileCopyrightText: 2025 LiveKit, Inc.
//
// SPDX-License-Identifier: Apache-2.0
import {
  type JobContext,
  type JobProcess,
  WorkerOptions,
  cli,
  defineAgent,
  llm,
  voice,
} from '@livekit/agents';
import * as deepgram from '@livekit/agents-plugin-deepgram';
import * as elevenlabs from '@livekit/agents-plugin-elevenlabs';
import * as livekit from '@livekit/agents-plugin-livekit';
import * as openai from '@livekit/agents-plugin-openai';
import * as silero from '@livekit/agents-plugin-silero';
import { fileURLToPath } from 'node:url';
import { z } from 'zod';

// Shared data that's used by the storyteller agent.
// This structure is passed as a parameter to function calls.
type StoryData = {
  name?: string;
  location?: string;
};

// Use inheritance to create agent with custom hooks
class IntroAgent extends voice.Agent<StoryData> {
  async onEnter() {
    this.session.generateReply({
      instructions: '"greet the user and gather information"',
    });
  }

  static create() {
    return new IntroAgent({
      instructions: `You are a story teller. Your goal is to gather a few pieces of information from the user to make the story personalized and engaging. Ask the user for their name and where they are from.`,
      tools: {
        informationGathered: llm.tool({
          description:
            'Called when the user has provided the information needed to make the story personalized and engaging.',
          parameters: z.object({
            name: z.string().describe('The name of the user'),
            location: z.string().describe('The location of the user'),
          }),
          execute: async ({ name, location }, { ctx }) => {
            ctx.userData.name = name;
            ctx.userData.location = location;

            const storyAgent = StoryAgent.create(name, location);
            return llm.handoff({ agent: storyAgent, returns: "Let's start the story!" });
          },
        }),
      },
    });
  }
}

class StoryAgent extends voice.Agent<StoryData> {
  async onEnter() {
    this.session.generateReply();
  }

  static create(name: string, location: string) {
    return new StoryAgent({
      instructions: `You are a storyteller. Use the user's information in order to make the story personalized.
        The user's name is ${name}, from ${location}`,
    });
  }
}

export default defineAgent({
  prewarm: async (proc: JobProcess) => {
    proc.userData.vad = await silero.VAD.load();
  },
  entry: async (ctx: JobContext) => {
    const userdata: StoryData = {};

    const session = new voice.AgentSession({
      vad: ctx.proc.userData.vad! as silero.VAD,
      stt: new deepgram.STT(),
      tts: new elevenlabs.TTS(),
      llm: new openai.LLM(),
      // to use realtime model, replace the stt, llm, tts and vad with the following
      // llm: new openai.realtime.RealtimeModel(),
      userData: userdata,
      turnDetection: new livekit.turnDetector.EnglishModel(),
    });

    await session.start({
      agent: IntroAgent.create(),
      room: ctx.room,
    });

    const participant = await ctx.waitForParticipant();
    console.log('participant joined: ', participant.identity);
  },
});

cli.runApp(new WorkerOptions({ agent: fileURLToPath(import.meta.url) }));