The Decoupling Mechanism as a Boundary Condition: Geometric Resolution to the Dark Sector and Hubble Tensions

Macroscopic astrophysical parameters are operationally inferred at radiative decoupling surfaces. We define a dimensionless boundary invariant, , coupling measurable radiative observables with Newtonian surface gravity. Under standard macroscopic closures, reduces identically to a geometric capacity . Using strictly independent solar measurements yields . Evaluating for a benchmark sample of 190 detached eclipsing-binary components shows tight clustering at , with no systematic trend over . We then project this empirically established local decoupling normalization to the vacuum boundary of the cosmic horizon, obtaining the unified boundary relation . This yields as a parameter-free geometric fraction. In this boundary formulation, the canonical vacuum discrepancy is a dimensional mismatch between a surface capacity and a bulk density, consistent with the holographic scaling . Finally, treating the late-time transition from a continuous early-universe fluid to a discretized void network as a topological packing offset suggests a fixed kinematic mapping , placing for .