`setResponseHeaders` and `setResponseStatus` don't work in global middleware

[nickprinsloo]

Which project does this relate to?

Start

Describe the bug

When setting response headers using setResponseHeaders or response status using setResponseStatus in a global middleware server handler, the headers and status are not set.

setResponseHeader works as expected.

Your Example Website or App

https://github.com/nickprinsloo/tss-example

Steps to Reproduce the Bug or Issue

Given the following start.ts:

import { createMiddleware, createStart } from "@tanstack/react-start";
import { setResponseHeaders, setResponseStatus } from "@tanstack/react-start/server";

const requestMiddleware = createMiddleware().server(({ next }) => {
  const headers = new Headers()
  headers.set("X-Hello", "World")
  headers.set("X-Foo", "Bar")
  setResponseHeaders(headers)
  setResponseStatus(404)
  return next()
})

export const startInstance = createStart(() => {
  return {
    requestMiddleware: [requestMiddleware],
  };
});

I'd expect the custom headers + status to be present on the response.

Expected behavior

As a user, I expect to see the headers and status of the response to be those set in the global middleware.

Screenshots or Videos

No response

Platform

• Start: ^1.132.48
• Node: v22.19.0
• macOS Tahoe

Additional context

No response

[chrstntdd]

Ran into this as well.

Sounds like they're actively working on header manipulation. Root cause is likely related to this parent issue.

See #5537 (comment).

The author of that PR suggested this as a possible workaround. I did have to restart the dev-server though:

import { createMiddleware, createStart } from "@tanstack/react-start";
import { setResponseHeaders, getResponseHeaders, setResponseStatus } from "@tanstack/react-start/server";

const requestMiddleware = createMiddleware().server(({ next }) => {
  // Access typed headers
  // -------------VVVVVVVVVVVVVVVVVV
  const headers = getResponseHeaders()
  headers.set("X-Hello", "World")
  headers.set("X-Foo", "Bar")
  setResponseHeaders(headers)
  setResponseStatus(404)
  return next()
})

export const startInstance = createStart(() => {
  return {
    requestMiddleware: [requestMiddleware],
  };
});