The structural validation layer is worth separating from the semantic layer, even if the semantic problem is harder. If every AI-proposed change is validated against a JSON Schema before execution, and that validation produces a deterministic, signed result, you get an auditable record of what passed structural checks and when. That doesn't solve semantic drift (a field can be renamed and still pass validation) but it gives you a foundation to build semantic checks on top of. The key property is determinism: identical schema and payload should produce identical hashes and outcomes, regardless of which service runs the check. Without that, you end up debugging whether a failure is in your schema logic or in validator implementation differences across languages. Contract tests and regression evals work better when the structural layer underneath is provably consistent. One reference for this pattern: https://docs.rapidtools.dev/openapi.yaml