Can a contrastive dual-encoder (FcCALM, after CALM/MRC) generalize where a one-hot verifier can't? A two-axis result across 13 runs: the receptor encoder does generalize to an unseen FcγR (leave-one-out AUROC 0.72–0.84, ≈no penalty ex-FcRn — the gospel's headline claim, validated), but the model does not rank binding at unseen Fc positions — confirmed even by a fully-faithful 1-to-1 build (per-receptor co-crystal pooling, hard-neg families 2–3, cross-attention, 5× data — all chance OOD, best-in-zone). Verdicts on MRC & CALM, fidelity-to-spec accounting, corrected gospel PDB errors.