A Falsifiable Geometric–Thermodynamic Framework for Emergent Cosmic Acceleration

We present a falsifiable, test-driven framework to assess the hypothesis that latetime cosmic acceleration emerges from the thermodynamic and geometric properties of spacetime rather than from a fundamental cosmological constant. The manuscript is organized into three operational criteria. Criterion A reconstructs the background expansion directly from model-independent data without assuming a fundamental Λ. Criterion B tests whether the reconstructed background is internally consistent with the observed linear growth of structure under standard General Relativity. Criterion C1 closes the program for a concrete realization by estimating, from observations, the single dimensionless parameter that controls the acceleration scale in the Jacobson-motivated holographic dark energy (HDE) completion. Using Pantheon+ Type Ia supernovae and the DESI 2024 combined BAO likelihood (ALL, full covariance), we obtain an empirical best fit cbest = 0.95 with χ2 min = 914.327 for the adopted SN+BAO likelihood pipeline (real-data run). These results do not by themselves validate an emergent-acceleration ontology, but they implement the intended logic of the program: The hypothesis is made testable, the parameter is measurable, and any future thermodynamic first-principles prediction for c becomes a direct pass/fail target.