Exact full-code recovery and its obstructions

This is the constant-complement form of the established Knill–Laflamme condition KnillLaflamme. Comparable finite criteria are recorded in Cheung's Hawk04-A, En07-A, Hawk03-A, Hawk01-B, VII-G, and Em05-B CheungHawk04A,CheungEn07A,CheungHawk03A, CheungHawk01B,CheungVIIG,CheungEm05B. The proof above does not import their model-specific channels.