Third and fourth models on the spinel A-site preference ladder: ORB-v3 (orb_v3_conservative_inf_omat, float64) and MACE-MP-0 medium, plus a harness check reproducing the MACE-MP-0 small numbers exactly. Per-gamma static energies for gamma = 0, 0.5, 1 on the frozen ZnFe2O4 oxygen sublattice, six chemistries.