Memory not working when using chatRoute and useChat from ai-sdk

export const mastra = new Mastra({
  agents: {
    tourGenerator: tourGeneratorAgent,
  },
  storage: new LibSQLStore({
    id: "main-store",
    url: "file:./mastra.db",
  }),
  server: {
    apiRoutes: [
      chatRoute({
        path: "/tour-chat",
        agent: "tourGenerator",
      }),
    ],
  },
});

export const tourGeneratorAgent = new Agent({
  name: "tour-generator",
  id: "tour-generator",
  instructions: '....',
  model: anthropic("claude-haiku-4-5"),
  memory: new Memory(),
});

  const { messages, sendMessage, status, error } = useChat({
    experimental_throttle: 30,
    transport: new DefaultChatTransport({
      api: `${mastraApiUrl}/tour-chat`,
      prepareSendMessagesRequest({ messages }) {
        console.log({
          thread: threadId,
          resource: "user",
        });
        return {
          body: {
            messages,
            memory: {
              thread: threadId,
              resource: "user",
            },
          },
        };
      },
      fetch: async (url, init) => {
        if (init?.headers) {
          const headers = new Headers(init.headers);
          headers.delete("User-Agent");
          init.headers = headers;
        }
        return fetch(url, init);
      },
    }),
  });

"memory":{"thread":"36ae96e6-267f-4815-957c-7adac18332b7","resource":"user"}}