Calling server function within another server function inside loader alters parameters unexpectedly

[jadedevin13]

Describe the bug

When calling a server function inside another server function, the parameters get altered unexpectedly, causing the outer function to receive modified parameters. This issue prevents the function from being reusable as intended.

Your Example Website or App

N/A

Steps to Reproduce the Bug or Issue

1. Define two server functions using createServerFn:

export const serverFn = createServerFn('POST', async (params, ctx) => {
  console.log(params)
  await server2Fn(params)
  return null
})

export const server2Fn = createServerFn('POST', async (params, ctx) => {
  console.log(params)
  return null
})

2. Call the serverFn function with the following parameters:

   // inside a loader
   await serverFn({ slug: { eq: 'test' } });
   

3. Observe the console logs for params within serverFn:

   Expected output:

   { "slug": { "eq": "test"} }
   

   Actual output:

   {
     "method": "POST",
     "payload": { "slug": { "eq": "test" } },
     "requestInit": undefined
   }
   

Expected behavior

The createServerFn wrapper seems to be adding extra data to the parameters, such as method, payload, and requestInit. This behavior interferes with the intended parameter structure, making it difficult to reuse the server function properly.

Screenshots or Videos

No response

Platform

• OS: macOS
• Browser: Chrome
• Version: "@tanstack/react-router": "^1.43.3", "@tanstack/start": "^1.43.3"

Additional context

No response

[jadedevin13]

I found that simply replacing the following lines

https://github.com/TanStack/router/blob/bf52d5af9c80a99e1141c30ebb67999ecd4b24de/packages/start/src/client/createServerFn.ts#L85-L92

with

  return Object.assign(
    async (payload, opts) => {
      return compiledFn(payload, opts);
    },

Solves my issue and doesn't cause issues with other server functions even when called in the react component. So I'm not sure why it's being called with those extra args.