This is the antithesis of OOP. Behavior should be modeled with data, not around data. Given a new use-case (some mutation of state), how can you be sure that an

This is the antithesis of OOP. Behavior should be modeled with data, not around data. Given a new use-case (some mutation of state), how can you be sure that an invariant is not bypassed if invariants are modeled at the level of each use-case? Any solution to the above begs the question, as all you will have done is distributed your “domain object” across the filesystem. Your system would be better served to simply put all the rules and objects into a single file which brings us back to original claim.