Sound and Deterministic Quadric Arrangements on a Rational Ellipsoid with Machine-Checkable Certificates

Preprint. We present a deterministic arrangement kernel for rational quadric surfaces on a rational ellipsoid, with exact rational and algebraic arithmetic, a multi-chart stereographic atlas, rejection certificates, and scoped reproducibility artifacts. The deposit includes the paper PDF, SHA-256 list, and a source-and-artifact archive. The source archive contains the GPL research kernel, Lean proofs, test vectors, artifact tables, and reproduction scripts. Licenses: paper CC BY 4.0; research code and Lean proofs GPL-3.0-or-later; artifact data CC BY 4.0. The Axiom product QA core is not included.