i sketched out the “how to unify root selection” idea from https://pantsbuild.slack.com/archives/C046T6T9U/p1594249199162500 in a doc: https://docs.google.com/document/d/10F8bi-Es2CjfpvZcxNH-3xb0vPhlq3cQljNHmdI-zNg/edit# … would love feedback!