koajs: how to wait for client to receive file?

Question

I want to return a generated file with koa (2) and after the client finished receiving the file, the file should be deleted.

// this function is called by Koa
async myMethod (ctx) {
  const file = await something()// generate a file

  ctx.attachment(path.basename(file))
  ctx.body = fs.createReadStream(file)

  // how can I await here for the client to fully receive file?

  await fs.promises.unlink(file)
}

I could do this:

ctx.body.on('end', async () => { 
  console.log('client finished receiving') 
  await fs.promises.unlink(file)
})

but I would rather put the delete logic in a separate middleware, and therefore I have to wait for the file to be fully sent before returning from the function