Bio-Cubic Universe — Paper VII DESI DR2 Confirmation of the Bio-Cubic Framework: The Hubble Tension Reduced to 2.51 Sigma with Six BAO Tracers MCMC v4 — 9 Parameters — 1,280,000 Samples — DESI DR2 BAO (z = 0.51 to 2.33)

DESI DR2 : beta = 0.196 +/- 0.059 (3.3 sigma) | H0: 5.60sigma -> 2.51sigma | ln(B12) = +13.98 DECISIVE THE TRIPTYQUE HOLDS : g/lambda = 1.80 | S8 + H0 + tau_vide simultaneously n = 2.019 (Z2 universality class — 7th independent confirmation) Abstract We present results from the fourth MCMC run (v4) of the Bio-Cubic cosmological model, incorporating for the first time the DESI DR2 BAO constraints (arXiv:2503.14738, Phys. Rev. D 112, 083515, 2025). The DESI DR2 dataset provides six BAO tracers from z = 0.51 to z = 2.33, including the first sub-percent BAO measurement at z > 2 from the Lyman-alpha forest, replacing the three BOSS DR12 tracers used in MCMC v3 (Paper VI). The key new result is a dramatic improvement in the Hubble tension resolution: with DESI DR2 constraints, the H0 tension is reduced from 5.60 sigma (LambdaCDM) to 2.51 sigma (Bio-Cubic v4), compared to 4.19 sigma in v3. This improvement is driven by a significant upward shift in the decoherence parameter beta from 0.089 +/- 0.039 to 0.196 +/- 0.059 -- now detected at 3.3 sigma from zero, constituting the first robust detection of this parameter. The spectral index n = 2.019 is confirmed for the seventh time, establishing the Z2 universality class. The Bayesian evidence increases to ln(B12) = +13.98 (decisive). The vacuum remains stable (beta_crit margin 11.1 sigma) and the GW prediction Omega_GW = 7.15 x 10^{-12} remains within the LISA 2034 detection horizon. The Triptyque -- g/lambda = 1.80 simultaneously controlling S8, H0, and the vacuum lifetime -- is confirmed with DESI DR2 data.