ψ–Retentive Correction to the Friedmann Expansion: A Three-Diagram Architecture

This technical note introduces a ψ-retentive correction to the classical Friedmann expansion, formulated within the internal architecture of ψ-cosmology. The framework inserts a structural retention node (Ξ) into the expansion flow, preserving a minimal differential of difference (Δψ) even when curvature, coordinates, and external time approach degeneracy. Three diagrams summarise the architecture: (1) insertion of Ξ inside the Friedmann pipeline; (2) the ψ–Λ retentive expansion map across GR and ψ-time regimes; (3) the ψ-horizon structure, where retention remains active beyond geometric collapse. The note presents a structural supplement to standard cosmology, introducing an internal retentive axis that operates independently of curvature, density, and the classical cosmological constant. The ψ-Lagrangian formalism is included to outline the dynamical behaviour of Δψ in post-metric regimes. This work is part of the Zenodo ψ-Series (2025) and contributes to the development of ψ-cosmology as a retentive framework applicable near horizons, collapse boundaries, and early-universe conditions.