A Finite Atlas for One-Hidden Seam Fibers in Signed Boolean Ideal Lifts

A checked finite atlas at denominator 5 for one-hidden seam fibers in signed Boolean ideal lifts. The release contains the raw atlas data, a portable certificate stream with 91,902 rows, an independent TypeScript checker, mutation tests, a reproducibility paper and a deliberately shallow Lean theorem over an aggregate certificate. At denominator 5 there are 5,191 rows: 5,153 resolved and 38 on the bounded frontier. The 38 frontier rows are not negative certificates. Each of the 26,438 positive outcomes carries a witness. Across the nine checked cores, the strict subfloor partition is 74,484 = 74,468 one-sided + 16 coordinated parent glue + 0 legal/residual. The release makes no claim about denominator 6, all dimensions, general reachability or non-reachability, an invariant that is both necessary and sufficient for the 16 rows, or a complete Lean formalization. The code and tooling are MIT. The atlas data, certificates, documentation and paper are CC BY 4.0. Terms for the embedded fonts are recorded inside the archive.