Why Are Custom System Instructions Ignored in My OpenAI Realtime API Chatbot on Node.js?

I'm building a realtime audio chatbot in Node.js using OpenAI's Realtime API. The chatbot works without errors, but my custom system instruction doesn't apply and it defaults to "ChatGPT assistant." I've tried several variations of the system instruction following the documentation closely, but none take effect. Am I missing something?

Here is the relevant code snippet:

JAVASCRIPTCopied
const express = require("express");
const { RealtimeClient } = require("@openai/realtime-api-beta");
const record = require("node-record-lpcm16");
const Speaker = require("speaker");
require("dotenv").config();

let recordingProcess = null;
let isStreaming = false;

// OpenAI Realtime API client
const realtimeClient = new RealtimeClient({
  apiKey: process.env.OPENAI_API_KEY,
});

let isConnected = false;

// Initialize OpenAI Realtime API session
const initializeRealtimeClient = async () => {
  if (isConnected) {
    console.log("Realtime client already connected.");
    return;
  }

  realtimeClient.updateSession({
    instructions: "You are Sara, A friendly chatbot who loves to talk about herself and is very intrested in marinebio",
    input_audio_transcription: { model: "whisper-1" },
    turn_detection: { type: "server_vad" },
    voice: "nova",
  });
;
 realtimeClient.on("conversation.updated", ({ delta }) => {

    if (delta?.audio) {
      playAudioResponse(delta.audio); // Play the audio response
    }
  });

  try {
    await realtimeClient.connect();
    console.log("Connected to OpenAI Realtime API.");
    isConnected = true;
  } catch (error) {
    console.error("Error connecting to Realtime API:", error);
    isConnected = false;
  }
};

// Start streaming audio
const startStreaming = async () => {
  if (isStreaming) {
    console.log("Streaming is already active.");
    return;
  }

  await initializeRealtimeClient();

  console.log("Starting audio streaming...");
  isStreaming = true;

  recordingProcess = record.record({
    sampleRate: 24000,
    channels: 1,
    threshold: 0.5,
    device: "VB-Cable"
  });

  const audioStream = recordingProcess.stream();

  audioStream.on("data", (chunk) => {
    if (!isConnected) {
      console.warn("Realtime client is not connected. Skipping audio chunk.");
      return;
    }

    const int16Array = new Int16Array(chunk.buffer, chunk.byteOffset, chunk.byteLength / 2);

    if (int16Array.every((value) => value === 0)) {
      console.warn("Skipping zero-filled chunk...");
      return;
    }

    try {
      realtimeClient.appendInputAudio(int16Array);
    } catch (error) {
      console.error("Error appending audio chunk:", error);
    }
  });

  console.log("Audio streaming started.");
};

// Routes
app.get("/start-streaming", async (req, res) => {
  try {
    await startStreaming();
    res.send("Audio streaming started.");
  } catch (error) {
    console.error("Error starting streaming:", error);
    res.status(500).send("Error starting streaming.");
  }
});