Start - Await component with Date (type mismatch)

[perfectbase]

Which project does this relate to?

Start

Describe the bug

Hey team! I think I found a bug with how the Await component handles serialization.

Here’s what’s happening:

• If I pass a Date object directly from the loader, everything works fine — it’s recognized as a real Date.
• But if I return a Date from a promise (e.g., via Await), the value looks like a Date in TypeScript, but it is a string at runtime.

You can reproduce it with this minimal example:

import { Await, createFileRoute } from "@tanstack/react-router";
import { createServerFn } from "@tanstack/react-start";
import { Suspense } from "react";

const getDate = createServerFn({ method: "GET" }).handler(async () => {
  await new Promise((resolve) => setTimeout(resolve, 1000));
  return new Date();
});

export const Route = createFileRoute("/_authed/(home)/")({
  loader: async () => {
    return {
      date: new Date(), // This stays a Date
      datePromise: getDate(), // This gets turned into a string
    };
  },
  component: Dashboard,
});

function Dashboard() {
  const { date, datePromise } = Route.useLoaderData();
  console.log("DATE", typeof date); // Logs "object" (correct)

  return (
    <Suspense fallback={<div>Loading...</div>}>
      <Await promise={datePromise}>
        {(date) => {
          console.log("DATE2", typeof date); // Logs "string", even though TS says Date
          return <div>{date}</div>;
        }}
      </Await>
    </Suspense>
  );
}

Let me know if I’m missing something.

Thanks!

Expected behavior

I believe it should be a date inside the Await component. (Or the TypeScript type should be a string)

Platform

• OS: macOS
• Browser: Chrome
• Version: 1.114.27 (start)