Vacuum Tension and Global Saturation as the Physical Origin of the Maillot Invariant.

We identify the physical mechanism enforcing the universal saturation invariant previously established in confined, normalizable wave systems. Saturation is shown to arise from a balance between a generalized dilational force associated with finite configurations and a vacuum tension describing the coercive response of the physical vacuum to confinement. The equilibrium condition defines a stable attractor that dynamically enforces the Maillot invariant without introducing new fields or arbitrary parameters. In this framework, the vacuum behaves as a finite, elastic medium whose response regulates expansion and confinement across scales. Fundamental constants emerge as calibration parameters encoding this vacuum response, providing a non-arbitrary physical foundation for structural stability from microscopic systems to cosmological horizons.