Unable to catch my response of newmessage within UseStream

[m99Tanishq]

Frontend

const { isLoading, submit, values, messages } = useStream<{
messages: Message[];
}>({
apiUrl: langgraphServerUrl,
defaultHeaders: { Authorization: Bearer ${getToken()} },
assistantId: "payable-gpt",
threadId,
messagesKey: "messages",
});

const handleSubmit = async (
content: string,
files: File[],
agent_mode: string
) => {
if (isLoading) return;

const uploadedFiles: UploadedFile[] = [];
for (const file of files) {
  const result = await uploadFileController(file);
  if (result.url) uploadedFiles.push(result);
}

const newMessage = {
  type: "human" as const,
  content,
  additional_kwargs: {
    timestamp: new Date().toISOString(),
    component: { files: uploadedFiles },
  },
};
setChatThread((prev) => [
  ...prev,
  {
    id: Date.now(),
    content,
    role: "user",
    timestamp: new Date(),
  },
]);

submit(
  { messages: [newMessage] },
  {
    config: { configurable: { agent_mode } },
    //Optimistically adding message
    optimisticValues(prev) {
      const prevMessages = prev.messages ?? [];
      const newMessages = [...prevMessages, newMessage];
      return { ...prev, messages: newMessages };
    },
  }
);

};

useEffect(() => {
console.log("Messages:", messages);

if (messages.length > 0) {
  onMessage(messages[messages.length - 1]);
}

}, [messages]);

---------------------------------Backend---------------------------------------

export const XYZcontroller = asyncHandler(async (req, res) => {
res.writeHead(200, {
"Content-Type": "text/event-stream",
"Cache-Control": "no-cache",
Connection: "keep-alive",
});

const { threadId } = req.params;
const { input, config } = req.body;

if (!threadId) throw new AppError("Thread ID is required");

const files = input?.messages?.[0]?.additional_kwargs?.component?.files || [];
const uploadedFiles = files.map((file: any) => ({
fileName: file.name,
type: file.type,
fileUrl: file.url,
}));
try {
const eventStream = payableGptGraph.streamEvents(
{
user_message: [new HumanMessage(input.messages[0].content, { files })],
},
{
...config,
configurable: {
...config?.configurable,
streamMode: ["messages", "values", "custom"],
thread_id: pq-${req.clientId}-${req.userId}-${threadId},
token: req.token,
uploadedFiles,
},
version: "v2",
}
);

await streamWriter(
  { stream: eventStream },
  ({ event, name, tags, data }) => {
    if (event === "on_custom_event" && name === "widget") {
      const widgetPayload = JSON.stringify({ type: "widget", data });
      const content = `<json_data>${widgetPayload}</json_data>`;

      res.write(content);
    } else if (
      event === "on_chat_model_stream" &&
      tags?.includes("stream_response") &&
      isAIMessageChunk(data.chunk) &&
      data.chunk.content
    ) {
      res.write(data.chunk.content);
    } else {
      console.log(event, name, data);
    }
  }
);

res.end();

} catch (error) {
console.error(error);
res.write("event: error\n\n");
res.end();
}
});

my Response is a plain simple text that I am recieving from backend