This work introduces ψ-Retentive Gravity, a pre-singular field framework describing the persistence of structural differences in regimes where standard geometric and dynamical descriptions become insufficient. Motivated by late-time growth plateaus observed across multiple cosmological surveys, the theory formalizes retention as a complementary structural principle alongside dynamical evolution. The model is built on three structural invariants—retentive difference (Δψ), stability nodes (Ξ), and internal pseudotime (τ)—and is governed by a minimal retentive Lagrangian independent of metric collapse. A stable retentive plateau emerges naturally, yielding a well-defined threshold redshift z* ≈ 0.51–0.52, consistent with current observational windows of suppressed structure growth. ψ-Retentive Gravity is not proposed as a replacement for General Relativity or ΛCDM, but as a complementary framework applicable in near-degenerate or pre-singular regimes, offering a coherent structural description of persistence beyond purely dynamical cosmology.