LiveKit Agents

import "dotenv/config.js";
import { fileURLToPath } from "url";
import { BraintrustSpanProcessor, setupOtelCompat } from "@braintrust/otel";
import {
  cli,
  defineAgent,
  JobContext,
  ServerOptions,
  telemetry,
  voice,
} from "@livekit/agents";
import * as openai from "@livekit/agents-plugin-openai";
import { NodeTracerProvider } from "@opentelemetry/sdk-trace-node";
import { Resource } from "@opentelemetry/resources";
import {
  ATTR_SERVICE_NAME,
  ATTR_SERVICE_VERSION,
} from "@opentelemetry/semantic-conventions";

function setupBraintrustTelemetry() {
  // Setup OTEL compatibility for bidirectional interoperability
  setupOtelCompat();

  // Create BraintrustSpanProcessor with configuration
  const spanProcessor = new BraintrustSpanProcessor({
    apiKey: process.env.BRAINTRUST_API_KEY,
    apiUrl: process.env.BRAINTRUST_API_URL,
    parent: process.env.BRAINTRUST_PARENT,
    // Keep this false: LiveKit's voice spans use lk.* attributes, so AI-span
    // filtering would drop the session, user/agent speaking, and turn spans.
    filterAISpans: false,
  });

  const provider = new NodeTracerProvider({
    resource: new Resource({
      [ATTR_SERVICE_NAME]: "livekit-agent",
      [ATTR_SERVICE_VERSION]: "1.0.0",
    }),
    spanProcessors: [spanProcessor as any],
  });

  // Register the provider with OpenTelemetry's global API
  provider.register();

  // Configure LiveKit to use our tracer provider
  telemetry.setTracerProvider(provider, {
    metadata: {
      component: "livekit-agent",
    },
  });
}

export default defineAgent({
  entry: async (ctx: JobContext): Promise<void> => {
    // Setup telemetry
    setupBraintrustTelemetry();

    const session = new voice.AgentSession({
      llm: new openai.realtime.RealtimeModel({
        voice: "coral",
        temperature: 0.8,
      }),
    });

    await session.start({
      agent: new voice.Agent({
        instructions: `You are a helpful and friendly voice AI assistant`,
      }),
      room: ctx.room,
    });

    // Greet participant when they join
    const greetParticipant = async () => {
      session.say("Hello! I'm your voice assistant. How can I help you today?");
    };

    let greeted = ctx.room.remoteParticipants.size > 0;
    if (greeted) greetParticipant();

    ctx.room.once("participantConnected", () => {
      if (!greeted) {
        greeted = true;
        greetParticipant();
      }
    });

    // Wait for room to disconnect
    function waitForRoomDisconnect(room: typeof ctx.room) {
      return new Promise<void>((resolve) => {
        room.once("disconnected", () => resolve());
      });
    }

    await waitForRoomDisconnect(ctx.room);
  },
});

// Run the agent
cli.runApp(
  new ServerOptions({
    agent: fileURLToPath(import.meta.url),
  })
);