Referring to the zip file usage with RPK: I think I understand what you meant, but it wasn't me.
The zip file access is in multcart.c, and I contributed only some parts of it. Most lines from me are not concerned with reading from a zip file; I just use calls to find a file and to read it.
It's just multcart.c which deals with zip files, so if there are mechanisms in the core to handle folders and zip files in an equivalent way, you should be able to change that without doing any harm to upper layers.
