A Lean-Certified Endpoint-Shape Counterexample in the Branch-C Farey Mediator Program

This final-preprint revision presents a Lean-checked counterexample to one endpoint-shape coverage bridge in the finite Branch-C Farey mediator program. It explains why valid family results cannot be promoted to universal coverage without a separate boundary proof, preserves the original formal artifact, and adds a pinned replay package plus a second proof layer with a cleaner dependency report. The revision also shows that the counterexample still has a listed mediator, clarifying that the failed classification bridge and the mediator-existence target are different propositions. The package includes the manuscript, searchable PDF, exact Lean sources, toolchain pin, proof manifest, replay report, and SHA-256 release manifest. Its conclusions are limited to the assumptions, evidence, and testing conditions stated in the manuscript. It belongs to the arithmetic operator and Branch C research program. This is a corrected preprint edition released under the Creative Commons Attribution 4.0 license.