hi,
i am trying to use the new AI sdk from vercel to stream a response from a langchain agent in my api route, to a chat component in the frontend of my nextJS app.

It seems that if I put the handlers from LangChainStream() in the call to the agent, the stream ends prematurely (after the first llm call). If i put the handlers on the model, the stream never completes. I need it to complete to save the response to a database.

export const runtime = 'edge';

const handleRequest = async (messages) => {
  const { stream, handlers } = LangChainStream();

  const chat = new ChatOpenAI({
    streaming: true,
    temperature: 0.3,
    modelName: 'gpt-3.5-turbo',
    openAIApiKey: process.env.OPENAI_API_KEY,
    //can also put callbacks:[handlers] here
  });

  const tools = [calendlyTool, dbSearchTool];

  const prompt = ZeroShotAgent.createPrompt(tools, {
    prefix: '-'
    You have access to the following tools:
      TOOLS:`,
    suffix: '-'
  });

  const chatPrompt = ChatPromptTemplate.fromPromptMessages([
    new SystemMessagePromptTemplate(prompt),
    HumanMessagePromptTemplate.fromTemplate(`{input}
 
          This was your previous work (but I haven't seen any of it! I only see what you return as "Final Answer: [your final response here]".
          {agent_scratchpad}`),
  ]);

  const llmChain = new LLMChain({
    prompt: chatPrompt,
    llm: chat,
  });

  const agent = new ZeroShotAgent({
    llmChain,
    allowedTools: tools.map((tool) => tool.name),
  });

  const executor = AgentExecutor.fromAgentAndTools({ agent, tools });

  executor
    .run(
      JSON.stringify(
        messages.map((m) =>
          m.role == 'user'
            ? new HumanChatMessage(m.content)
            : new AIChatMessage(m.content)
        )
      ),
      [handlers]
    )
    .catch(console.error);

  return new StreamingTextResponse(stream);
};

export default async function POST(req) {
  const { messages } = await req.json();
  return handleRequest(messages);
}