private modelOutputBuffer: Map<string, string> = new Map();
  private modelOutputTimers: Map<string, NodeJS.Timeout> = new Map();

  private GAP_MS = 250;

  /**
   * Main handler for Vapi server messages.
   */
  async handleServerMessage(
    call: InferResultType<'call'>,
    data: Vapi.ServerMessage,
  ): Promise<void> {
    switch (data.message.type) {
      case 'model-output':
        return this.handleModelOutputUpdate(call, data.message);
      default:
        return;
    }
  }

  getModelOutputMessageSync(obj: Record<string, unknown>): string {
    let output = '';
    for (const [, value] of Object.entries(obj)) {
      if (value !== null && typeof value === 'object') continue;
      output += String(value);
    }
    return output;
  }

  async handleModelOutputUpdate(
    call: InferResultType<'call'>,
    data: Vapi.ServerMessageModelOutput
  ): Promise<void> {
    const callId = call.id;

    const chunk = this.getModelOutputMessageSync(data.output);

    // Append chunk to buffer
    const existing = this.modelOutputBuffer.get(callId) ?? '';
    this.modelOutputBuffer.set(callId, existing + chunk);

    // Clear any existing timeout
    const existingTimer = this.modelOutputTimers.get(callId);
    if (existingTimer) clearTimeout(existingTimer);

    // Debounce timer
    const timer = setTimeout(async () => {
      await this.flushModelOutput(call);
    }, this.GAP_MS);

    this.modelOutputTimers.set(callId, timer);

    this.logger.log(`buffered chunk for ${callId}: ${JSON.stringify(chunk)}`);
  }

  async flushModelOutput(call: InferResultType<'call'>): Promise<void> {
    const callId = call.id;

    const fullOutput = this.modelOutputBuffer.get(callId) ?? '';
    if (!fullOutput) return;

    this.logger.log(`FLUSHED final message: ${JSON.stringify(fullOutput, null, 2)}`);
  }