TypeScript type for request object for route handlers

So far I've been writing my routes like:

export const router = t.router({
  helloWorld: t.procedure.query(async (req) => "Hello World"),
})

export const router = t.router({
  helloWorld: t.procedure.query(async (req) => "Hello World"),
})

What would be the type for

req

req

if I wanted to extract my handlers like so:

const handler = async (req:?) => "Hello World"

export const router = t.router({
  helloWorld: t.procedure.query(hander)
})

const handler = async (req:?) => "Hello World"

export const router = t.router({
  helloWorld: t.procedure.query(hander)
})