Epistemic Isomorphism: Why Verification Cannot Escape the Generator

When generator and verifier share the same error topology, verification is structurally unable to expand fault coverage beyond generation — regardless of prompt variation, role separation, or iteration count. This note defines Epistemic Isomorphism, distinguishes it from Role Collapse, capability failure, and Signal Collapse, and documents an empirical instance with independent cross-level confirmation: a production codebase where same-axis auditing plateaued at ~20% bug-class discovery while orthogonal rotation reached ~80%. Independent topological analysis by Martin Brodeur (DOI: 10.5281/zenodo.19223165) confirms the geometric structure at the model level. The note introduces the first pre-registered structural predictions in this series (P1–P4, formulated prior to data inspection) and derives a diagnostic question. A finite diagnostic protocol is documented in the restricted version of this record.