Gravity's Transitional Role: Boundary-Mediated Persistence and the Collapse of Routing Freedom

Gravity is commonly treated as a single organizing mechanism across physical systems, from diffuse gas to black holes. Here we argue instead that gravity changes functional role across regimes as the available degrees of freedom for energy and structure routing collapse. We present a classification framework in which diffuse gas and threshold clouds persist through boundary-supported energy exchange, stars through gravity-enabled internal circulation, and compact remnants through progressively constrained motion. In the limiting case of black holes, gravity no longer acts as a mechanism of accumulation but as a geometric container, with all admissible interaction mediated at the boundary. This framework is classificatory rather than mechanistic and is consistent with existing gravitational descriptions within each regime. Observationally grounded examples from Galactic gas clouds illustrate the boundary-supported regime, while black holes define the terminal limit of routing freedom. Gravity thus transitions from an organizing force to a limiting geometry as structure becomes increasingly constrained.