Geometric flavor benchmarks on a cubic cell: exact identities, mass consistency, and falsification tests

We examine cubic-cell flavor prescriptions through algebraic identities, conditional benchmarks, and explicit falsification protocols. The normalized body-diagonal excess defines a metric quantity; assigning a phase proportional to that quantity gives 131.769145 degrees and a conditional leptonic CP benchmark of 197.653718 degrees. Equal singlet and doublet powers imply the Koide relation exactly, whereas cyclic permutation symmetry alone does not fix their ratio. The proposed mass formula yields 893.377799 at the pure phase and 1872.117747 at a corrected phase of 132.75 degrees. Its logarithmic sensitivity changes from 36.40 to 51.88 per radian between these points, without determining the required torsional correction. We supply calibrated exclusion criteria, transparent comparisons with published oscillation summaries, and reproducible technical figures. Future exposure curves are illustrative, not detector forecasts. The construction defines testable prescriptions but does not establish their derivation from finite-group holonomy, a complete PMNS mass model, or a calculated radiative matching mechanism for observed masses. Audited revision 2. Includes a four-page manuscript, five technical figures, source code and data provenance. Forecast-like curves are explicitly illustrative. Geometric phase and PMNS identification remain conditional prescriptions; no finite-group holonomy derivation or radiative matching calculation is claimed.