Breadcrumbs tell an agent where it is in your hierarchy, which is what lets it navigate up and sideways instead of returning to the homepage and starting over.
Impact is importance multiplied by the confidence tier’s weight — SPECIFICATION 1.0, RESEARCH 0.7, EMERGING 0.3, EXPERIMENTAL 0.1. Two rules backed by the same class of evidence therefore always carry the same weight, which is what makes the score reproducible rather than hand-tuned.