The Decoupling Mechanism as a Boundary Condition: A Geometric Resolution to the Cosmological Constant Problem

The manuscript tests whether radiative decoupling surfaces admit a scale-independent geometric normalization that can be evaluated at stellar photospheres and projected to the cosmic horizon. A dimensionless boundary invariant \mathcal{X} is defined from macroscopic observables and evaluated across 190 detached eclipsing-binary (DEB) components from Torres et al. (2010), showing clustering near the projected blackbody boundary capacity \mathcal{X}_0 = \pi^3/15. The same boundary normalization is projected to the Hubble horizon by equating the dimensionless horizon vacuum capacity \Lambda A_H with the spherical projection 4\pi\mathcal{X}_0, yielding a parameter-free prediction \Omega_\Lambda = \pi^3/45 \simeq 0.6890, consistent with Planck constraints. The factor of 3 in the denominator shift (15 \rightarrow 45) is the geometric signature of the 2D boundary-to-3D cosmological normalization. Supplementary material is provided as a separate archive containing (i) a self-contained Python verification script and (ii) a sample table describing the required structure of the machine-readable dataset (data.csv) used to reproduce the DEB evaluation. Files Main manuscript archive (PDF/LaTeX source + figures). Supplementary archive (verification code + sample table + dataset template / data.csv structure).