Everything in the previous lesson depends on a fact that was never stated: the log came from somewhere the plant could not author. Change that and the exercise collapses. A plant whose own software writes the record files exactly what the twin expects, because both are computing from the same model of what should have happened. The replay agrees perfectly. The derate is still there. The regulator sees a clean check and learns nothing, and the failure is silent — no error, no alarm, no missing data. This Institute has stated the same result in a different setting: a receipt computed by the host is the host's account of itself, and signing it changes its provenance rather than its truth. For a plant that changes ports, owners and jurisdictions, that is not a footnote. It is the first line of any specification for verifiable generation.