Builds a CI workflow that runs only the subset of tests impacted by a PR's changes - combines a per-test → source-file dependency map (built from coverage profiles or, in build-graph projects, queried from the build system itself like Bazel `rdeps`) with the PR's `git diff --name-only`, then selects the union of (impacted by changed files + previously failing + newly added). Always pairs with a periodic full-suite run so a misconfigured map can't silently shrink coverage. Use when the regression suite is large enough that PR-time CI is the bottleneck and a full run is reserved for nightly / pre-release.