Major Description
Starting v2.3.9 httpd's mod_cache implements a feature enabled by CacheDetailHeader - which in nature is very similar to our Via header feature but is easier to read and understand by spelling out why something was cached/missed/revalidated/etc.. in words - so it doesn't need a decoder ring.
Given that we already have Via headers feature it should be fairly easy to implement a logic for producing a very similar header our selves.