Server Request timeout response is delivered out of band

Seen in the forums here: https://discuss.lightbend.com/t/akka-http-mapresponse-ignores-some-responses/1975/6

Intuitively request timeouts happens while in the routing tree, but actually that's not how they are implemented, which means that for example mapResponse does not also transform the request timeout response if the timeout hits.

Can we improve, and make mapResponse also map timeout responses out of the box, or something else that makes it more intuitive combining a route with the timeout?

If not, can we use documentation to make it more clear that it happens at a lower level?