COS45A Geometric Admissibility Framework for Observable Decision Boundaries with Empirical Boundary Crossing (v2.3)

COS45 is a geometric admissibility framework operating at the observable decision layer. It defines a scalar decision variable ηₙ derived from spectral quantities of a data matrix HW. If ηₙ > 0, the configuration is declared ADMISSIBLE; if ηₙ ≤ 0, the result is NON-CONCLUSIVE. No claim is made beyond admissibility. All components are observable. The framework performs no structure detection, classification, or causal inference. Strict layer separation is enforced: EXACT → STRUCTURAL → LOCAL BRIDGE → OBSERVABLE → DECISION. Under null-calibrated thresholding, the NON-CONCLUSIVE regime is empirically observed as a consequence of the chosen quantile level. Under structured signal degradation, a crossing of ηₙ = 0 is