The Meissner effect—the expulsion of magnetic flux from a superconductor upon entering the superconducting phase—is traditionally described as a dynamical electromagnetic response or as a consequence of perfect conductivity. Both views obscure a deeper structural feature of superconductivity. This paper presents a theorem-level reclassification of the Meissner effect as a phase-defining kinematic constraint. Global superconducting phase coherence is formulated operationally as path-independent, gauge-invariant phase transport. It is shown that this minimal coherence condition is incompatible with non-zero interior electromagnetic curvature in simply connected bulk regions. Magnetic flux exclusion therefore follows as a logical consequence of coherence, rather than as a dynamical relaxation process. Penetration depth and flux quantization arise naturally as boundary and topological corollaries of this exclusion principle. Standard theoretical frameworks—London theory, Ginzburg–Landau theory, and BCS theory—are shown to be energetically and microscopically consistent realizations of this kinematic necessity, computing how the constraint is dynamically enforced and how measurable quantities arise once it holds. The result clarifies why the Meissner effect is universal, history-independent, and phase-defining, while remaining complementary to established microscopic and energetic descriptions. The analysis is fully gauge-invariant, corpus-independent, and does not rely on specific pairing mechanisms or material parameters.