V84: Action-Update Correspondence — A Unified ρ(t) Engine for Update-Driven Cosmology

We introduce the Action-Update Correspondence, a foundational framework for Update-Driven Cosmology (YAGC) that connects discrete variational updates to continuous phenomenological time via a state-dependent update density ρ(t). The core equation ρ(Σ, A; θ) = ρ₀(1 + γA)(1 + αΣ/Σc) with saturation encodes how accumulated update cost Σ and system activity A jointly determine the local "clock rate" of physical evolution. The V84 Engine provides a unified computational framework with five shared parameters that must simultaneously account for galaxy-scale anomalies, dark energy evolution, saturation phenomena, and particle mass hierarchy. This work establishes the theoretical foundation for cross-scale consistency tests.