A formal theoretical development of the Global Geometric Architecture Theory (GID) is presented as a geometric and deterministic alternativeΛCDM paradigm. In contrast to inflationaryscalarfieldsandaninitialtemporalsingularity,GIDpostulatesthattheobserv- ableUniverseemergesfromanintrinsicallyinhomogeneousglobalgeometrystructured by threecoherenthorizon-scale energydomains: ID0,ID1,and ID2. Two fundamental equations define the theory: (i) a geometric extension of Einstein’s fieldequationsinwhichthecosmologicalconstantΛisreplacedbyaneffectivecontribution to the energy–momentum tensor generated by the three domains; and (ii) a global closure relation stating that all large-scale cosmological observables are governed by the coupled dynamics of these domains. The present cosmic state results from a process of geometric erosion,correspondingtoa60–75%redistributionofthefoundationalmass-energycontent. The theory remains entirely within General Relativity, removes the physical necessity of both a Big Bang singularity and inflation, and yields a set of falsifiable predictions for CMB anisotropies, coherent bulk flows, Hubble-parameter anisotropy, Integrated Sachs– Wolfe (ISW) signals, and ultra-early structure formation. The framework is designed for direct empirical testing with Euclid, DESI, and forthcoming peculiar-velocity surveys Consolidation Note: This work formalizes and consolidates the analytical results, spatial scales,andgeometricparametersderivedfromthecumulativedataofourpreviousfounda- tional studies: • Phenomenological Evidence for Three Horizon-Scale Coherent Energy Regions and Cosmic Anisotropy, ZenodoDOI: 10.5281/zenodo.18119459. • Dynamic Interaction of Global Inhomogeneity Domains and Emergence of Observable Cosmological Geometry, Zenodo DOI: 10.5281/zenodo.18181885. • Dynamic Formation of Superclusters within the GID Framework, Zenodo DOI: 10.5281/zenodo.18181886.