Lluis Eriksson (2026). Noncommuting Block Measurements Generate Quantum Diffusion: A Three-Obstruction Convergence Hierarchy, a Noncommutative Connectivity Gap, and Exact Algebraic Architectures. AIRR.SCIENCE, ARR-2026-3A3YP2CEH79D4RV0, v1. https://airr.science/papers/ARR-2026-3A3YP2CEH79D4RV0/versions/v1/ Archived manuscript; ARR-2026-3A3YP2CEH79D4RV0 v1. Not peer reviewed by AIRR. Historical import; not assessed by AIRR.