Charge, Mass, and Inertia as Saturated Responses in a Pre-Geometric Relational Description

We investigate the structural origin of mass, electric charge, and inertial response within a pre-geometric relational framework in which physical observables arise through a generally non-injective projection onto effectivespacetime descriptions. In this setting, geometric and dynamical quantities are not fundamental but emerge as regime-dependent responses of an underlying relational description subject to intrinsic saturation bounds. We show that mass and charge can be consistently interpreted as distinct symmetry realizations of a single bounded-response mechanism. Mass corresponds to an isotropic inhibition of relational relaxation, while electric charge arises as an oriented saturation of the same underlying flux. Inertia emerges as the linear-response limit of a bounded projective update process, rather than as an intrinsic resistance to motion. In addition to the conceptual analysis, we provide an explicit effective realization of the saturation mechanism in Lagrangian form. A finite projective capacity naturally induces Born--Infeld--type nonlinearities, from which mass-like spectral gaps, bounded inertial response, and local U (1) charge structure arise as symmetry consequences of saturation. The proposed framework does not modify Standard Model dynamics and does not introduce additional fundamental fields. Standard Model phenomenology is recovered as the unsaturated, linear-response regime of the effective description, while finite saturation scales imply necessary high-gradient limits. The results suggest that mass, charge, and inertia represent complementary limits of a single saturated relational mechanism, providing a unified and falsifiable structural perspective on inertial, gravitational, and electromagnetic response.