The U-Cell Model Prediction Ω_m=0.3166, w=−1: Parameter-Free Consistency Test Against DESI DR1 BAO and Pantheon+ Supernovae

We test the U-Cell Model (UCM) prediction Omega_m=0.3166, w=−1 against DESI DR1 baryon acoustic oscillations (13 data points) and Pantheon+ Type Ia supernovae (24 binned distance moduli). Across 37 independent data points, the UCM achieves chi²/dof=1.29 with zero free parameters, indistinguishable from Planck ΛCDM (chi²/dof=1.30). The Bayesian Information Criterion favours UCM (ΔBIC=+3.26) because it achieves equal fit with one fewer fitted parameter. The CMB acoustic scale shows a 1.8σ tension, analysed in the companion paper (Paper 16).