One authority per fact

Each fact a system acts on has exactly one component that decides it and publishes it, and every consumer reads the published value rather than deriving its own. A second place that decides the same fact is a defect rather than a redundancy, because two independent classifiers produce two locally consistent answers that are never compared, so the system holds two truths and has nowhere to notice the contradiction. Instructing the two to agree is a promise; removing the second is a shape.