Hash Side-Effect Ledgers to Safely Validate Cleanup Refactors in Legacy Code

Software cleanup refactors can silently break production systems when hidden couplings—such as shared file paths, environment flags, or unnamed caches—shift without triggering existing unit tests. A proposed workflow addresses this by first recording a canonical ledger of all side effects produced by a module's public entrypoint across test fixtures, then storing a SHA-256 hash of that ledger in source control. Any subsequent cleanup commit is only accepted if the hash remains identical, confirming that no hidden behavior has changed. The protocol also enforces a 'file-touch budget,' limiting each cleanup to editing one implementation file and one test file to prevent scope creep. If the hash changes, the change must be reclassified as a behavior modification, documented with an intentional test, and resubmitted—preventing AI coding agents from disguising functional changes as style-only refactors.