The MMA–DMF framework connects cosmological “dark sector” phenomenology with quantum-foundational phenomena by treating a single screened scalar field as both a mediator of large-scale modified gravity and a stochastic vacuum bath responsible for gravitational decoherence. This paper consolidates the full, dated MMA–DMF validation record contained in the project materials (with an audited, frozen parameter set) and reports the complete test suite relevant to uncertainty and decoherence: (i) a strict Fluctuation–Dissipation Theorem (FDT) stability test for the Generalized Langevin Equation (GLE) memory kernel, which passes an energy-drift criterion of |slope| < 10−5 in long integrations; (ii) a dynamic contextuality roll-off test in which the CHSH Bell parameter transitions from the Tsirelson value S ≈ 2.828 at quasi-static settings to the classical bound S → 2 under fast modulation, quantified by explicit frequency-dependent suppression formulas; and (iii) a T-MAGIS atom-interferometry campaign prediction in which a density-modulated environment produces a detectable contrast loss ∆V ≈ 3.4 × 10−3 to 4 × 10−3 under representative configurations, with a tabulated scaling versus distance and interrogation time and a shot-noise sensitivity forecast yielding high signal-to-noise for hour-scale integration. We also summarize MMA–DMF-linked phenomenology across scales, including a joint cosmological likelihood structure with cross-covariance correction and representative reported values (H0, S8) ≈ (72.1 km s−1 Mpc−1, 0.761), plus a gravitational-wave echo delay estimate of ∆techo ≈ 32 ms for stellar-mass systems. The combined record constrains MMA–DMF by demanding simultaneous thermodynamic consistency of the stochastic sector, a controlled transition from contextual to classical correlations under finite response time, and a falsifiable laboratory decoherence signature under controlled density modulation.