How the ZIP format has exceptions and sans-io is justified.

Sans-IO is a programming design does not dictate how the implementation runs, but only what to do (as far as I understand).

The dependency inversion principle says that policies (what to do) should not depend on implementation details (how to do it) ‒ https://www.firezone.dev/blog/sans-io#:~:text=the%20dependency%20inversion%20principle%20says%20that%20policies%20(what%20to%20do)%20should%20not%20depend%20on%20implementation%20details%20(how%20to%20do%20it)