EFC Weak Lensing Phenomenology

We present a phenomenological framework for testing Energy-Flow Cosmology (EFC) against weak gravitational lensing observations. Starting from the EFC field equations, we demonstrate that the published EFC field equations do not predict modified lensing without additional structure. We introduce a minimal operational closure (Postulat A) that linearly couples entropy production to matter density, yielding an explicit modified gravity parameter μ(k,z) in standard cosmological perturbation form. We derive the resulting weak lensing predictions and present a complete validation protocol against Dark Energy Survey Year 6 (DES Y6) 3×2pt data, including explicit pass/fail criteria. This work does not claim that EFC explains the S8 tension; rather, it provides the minimal theoretical infrastructure required to test whether it can. All code is publicly available.