Get navigation transition state

What is the equivalent for the Next.js code below in Tanstack Start for finding whether you're in he process of navigating

let [isPending, startTransition] = useTransition()

startTransition(() => {
  router.push('https://example.vercel.sh/stuff?abc=123')
})

let [isPending, startTransition] = useTransition()

startTransition(() => {
  router.push('https://example.vercel.sh/stuff?abc=123')
})