Yeah - looks like RarDirectory implements Exists(), albeit in an incredibly inefficient fashion.

IMO your proposal (filename empty -> checking existence of the .zip file -> extract zip name + CFile::Exists() on it) seems the most efficient way to go.  That way you get real existence.

(One can argue that `zip://<something_that_doesnt_exist.zip>/` is an edge case, as it's unlikely to come from our VFS, but we mayaswell capture it)