Dark Energy as the Vacuum Value of the Entropy Field

This pre-publication draft introduces Unified Entropic Dynamics (UED), a framework featuring a dynamical scalar entropy field S(x) whose gradient defines local temporal orientation and contributes to vacuum stress-energy. We demonstrate that the field's relaxation toward a stable minimum S_min naturally yields an effective dark energy equation of state following the Chevallier–Polarski–Linder form, w(a) ≈ -1 + w_a(1 - a) with w_a > 0, where the benchmark value w_a ≈ +0.02 emerges without fine-tuning and aligns with current cosmological constraints. A joint forecast using near-term survey precision from Rubin, DESI, Euclid, and Roman suggests this prediction is testable at approximately the 2σ level, offering a clear, falsifiable signature for dark energy's dynamical origin tied to the vacuum value of S(x).