We present a first-principles derivation of dark energy dynamics from the unified field framework of the Information-Causal Compression Field (ICCF) theory. By modeling vacuum compression fields as topological and entropic structures, we reinterpret dark energy as a dynamical phenomenon emerging from the interplay between compression tensor flow and entropy gradient divergence. Building upon prior work on particle stability, particularly the 41.2 GeV solitonic solution, we derive a causal field equation for λ(t), the time-dependent dark energy density, and establish its physical and geometric origin as an entropic residual of unstable compression modes. This theory provides a testable, falsifiable model for the slowing of cosmic acceleration and unifies massive and massless field behavior under a single compressive geometry.