Cool post. I don’t fully understand what a code contract is but appreciate the advice. I have settled on a similarly light weight /agile folder when I keep my roadmap.md with epics and sprints.
Depending on your backend you either ignore them, check them all of the time, some of the time, or have SMT-solvers prove that if you uphold the first one all else must follow.
If you're interested in the last one, have a look at Dafny[0]