Cosmological Imprints of K₈ Compactification: The Orbifold Aspect-Ratio Identity rₛ/d₄ₐ = ₂ and CMB Low-Multipole Suppression from Spinᶜ Holonomy: MNRAS Preprint

We present two cosmological predictions of the twelve-dimensional Riemannian framework M₁₂ = (S¹ₒ₎₋ S³) K₈, which obtains the cosmological constant (₄₅₅ 10^-122 M₏₋⁴), the Weinberg angle, and the dark matter abundance ratio from compactification geometry with zero continuous free parameters. First, the internal orbifold aspect ratio ₂ = 1. 86—dynamically locked by Spinᶜ flux stabilisation through a closed-form polynomial Qw² = 12₂⁴ + 2₂²—identifies the observed ratio of cosmological imprint scales rₛ/d₄ₐ 147/79 1. 86 as a single internal geometric datum rather than a coincidence of six independent parameters. Second, the Spinᶜ holonomy on K₈ assigns successive quarter-period phases \1, i, -1, -i\ to the four fixed points of the T²/Z₂ orbifold; the corresponding Z₄ sum vanishes identically, and the same holonomy that produces the Weinberg angle at particle scales cancels the coherent neutrino-ISW contribution to the CMB at the lowest multipoles, yielding C₂/C₂ -8\% and C₃/C₃ -14\%, with negligible suppression at 5. Both predictions agree with current data—the aspect-ratio identity to 0. 5%, the CMB low-multipole suppression to within statistical uncertainty of the ~ 10% and ~ 15% Planck deficits. The BAO sound horizon, S³ halo suppression, and Sol-induced disk-formation results of the same framework are reported separately in the companion preprints. Three falsifiable predictions for Planck legacy reanalysis, Simons Observatory, and Euclid are stated.