Two-Sector Gravity: Background Screening, Inertial Response, and the Origin of Dark Matter Phenomenology

We present a two-sector (two-representation) formulation within Basic Ontodynamics in which observed gravitational anomalies arise from the mismatch between a geometric background representation and an inertial response representation of the same underlying actualization flow. The background sector is governed by the scalar field ϕ = ln ρ4, whose dynamics reproduces Newtonian gravity in the weak field limit and whose covariant completion was established in previous work. The response sector is encoded by an effective inertial factor μ(ρ123), determined by the local coherence structure of the ambient medium. The resulting equation of motion reads a = J4 / μ(ρ123) = −∇ϕ / μ(ρ123) , showing that the observed acceleration is the directed actualization flow renormalized by the position-dependent inertial response. In the galactic regime this naturally produces flat rotation curves, the radial acceleration relation, and the full dark-matter phenomenology without invoking additional particle species. Lensing and dynamical mass estimates probe different representations of the flow and therefore need not coincide.