Eric Abrahamsen wrote:

> The real problem (well, one of the real problems) is that we should just
> have two central routines for reading and writing active files, so that
> there are only two places to keep in sync. Instead we have those two
> places, and then a smattering of other functions in other places that do
> something similar, and also have to be kept in sync, and I haven't done
> that. At the very least I'll need to apply your patch from 65467.
>
> The other real problem is that gnus-cache is confused about whether it
> wants to be a select method, or a modified version of article saving.
> The presence of `gnus-use-long-file-name' indicates the latter, but the
> manual's instructions about the nnml select method indicates the former.
>
> I think it should be a select method, which means that the group
> directory should be created in "News/cache" the same way it is created
> at the top level: with the "/" replaced by "_", and everything else
> using the proper "left/right" group name. Perhaps "long file names" can
> still play a role, but if so that should be via
> `nnmail-use-long-file-names', and gnus-cache in general should behave
> like a nnmail backend.

Well, I have sort of, an approach based on my earlier patch: