Finite witnesses, payer curvature, and certified reductions for Seymour's second-neighborhood conjecture at minimum out-degree eight

We study Seymour's second-neighborhood conjecture at minimum out-degree eight using degree-independent structural tools from a separately published companion paper and proof-producing finite reductions. We independently reconstruct the minimum-out-degree-seven boundary, obtain the exact degree-eight witness range 19 <= n <= 37, eliminate the top-level rows (5,3), (6,2), (6,3), and (7,1), and exclude every spanning-arc-minimal, order-twenty degree-eight order-minimal branch of minimum indegree at least six using eight independently checked LRAT certificates. The full minimum-out-degree-eight case remains open: the top-level rows (7,2) and (7,3) survive. This record contains the version 1.0.0 paper, source, deterministic proof archive, manifests, replay scripts, and exact generators.