action.ts

'use server'

export function doSomething(){}

action.ts

'use server'

export function doSomething(){}

client-component.tsx

'use client'

import { doSomething } from './action.ts'

function MyForm(){
  return (
    <form action={doSomething}> </form>
  )
}

client-component.tsx

'use client'

import { doSomething } from './action.ts'

function MyForm(){
  return (
    <form action={doSomething}> </form>
  )
}