A Unified Dark Sector from Dynamical-Ledger Drift

We propose a unified dark-sector interpretation of dynamical-ledger quantum gravity in which context drift, forced by moving-reference modular bookkeeping, admits an effective local completion that behaves cosmologically as both cold dark matter and a time-dependent vacuum response. The dynamical ledger adds a compulsory drift term to fixed-reference balance; under a representability hypothesis this drift compresses to a conserved stress tensor that can be treated as a single dark sector. On homogeneous backgrounds, conservation of the single drift-sector tensor implies an exact exchange identity for its vacuum-like/matter-like decomposition, where the vacuum-like piece has equation of state p = - ρ and the matter-like piece can behave as dust. We argue that a nonabelian completion provides a plausible route to a mass gap supporting a cold component, while covariance together with screen-scale coarse-graining motivates a leading background-effective vacuum response whose reduced running-vacuum parameterization can be taken of H2 type. The framework produces algebraic constraints tying vacuum fraction and dark-matter fraction at the background level.