fromSourceIO for endpoint with Headers

[vlatkoB]

I'm trying to make an endpoint which streams bytes (i.e. file) and sets 'Content-Disposition' header for suggested filename. Because the Swagger complains that ByteString is impossible, I have the newtype around it

type API = "file" :> StreamGet NoFraming OctetStream (Headers '[ContDispHdr] StreamData)

newtype ByteStream  = ByteStream {unBS :: BS.ByteString} 
                      deriving (Generic, Show, Semigroup)

type ContDispHdr = Header "Content-Disposition" String
type StreamData  = SourceIO ByteStream

server :: Handler (Headers '[ContDispHdr] StreamData)

curl and httpLbs seem to work correctly, however, client function complains about missing FromSourceIO

getFile :: ClientM (Headers '[ContDispHdr] StreamData)
getFile = client (Proxy :: Proxy API)

instance FromSourceIO ByteStream (Headers '[ContDispHdr] StreamData) where
  fromSourceIO _src = ???

I (obviously) failed in creating one, so could someone help in how to do it or
is there a better way in creating the endpoint that

• returns a stream
• sets different 'Content-Disposition' header
• sets different 'Content-Type' header (depending on the stream type)?

I have a file for testing