Exact non-scattering homogeneous dielectrics from Schiffer counterexamples

A proof of bounded, simply connected, noncircular homogeneous isotropic dielectric inclusions that are exactly non-scattering for an explicit normalized Herglotz incident wave in the two-dimensional scalar Maxwell reduction. The release separates the focused research article from a verification supplement containing exact-rational verifiers that rederive the perturbation constants from the certified ball bounds, a replayed and machine-compared pin of the upstream Colbrook--Stepaniants certificate, a narrow Lean 4 re-verification of the certificate arithmetic, reproducibility logs, and arXiv-ready source.