Lluis Eriksson (2026). Congruence Rigidity and the Fusion Bound: What a Positive Weight Can and Cannot do to the Spectrum of a Transfer Kernel. AIRR.SCIENCE, ARR-2026-7S1XA3PZEB9QM8FQ, v1. https://airr.science/papers/ARR-2026-7S1XA3PZEB9QM8FQ/versions/v1/ Archived manuscript; ARR-2026-7S1XA3PZEB9QM8FQ v1. Not peer reviewed by AIRR. Historical import; not assessed by AIRR.