Galactic Rotation Without a Dark Halo

With locally fixed occupation and isotropic gravitational coupling, a positive Hamiltonian yields a cubic field-energy density that produces flat outer rotation and the baryonic Tully-Fisher relation. Unequal source couplings to its two internal sectors preserve this low-acceleration law and recover the high-acceleration Newtonian limit. The absolute scale depends on geometric matching, while Solar-System constraints motivate a finite-coherence screening hypothesis whose dynamics remains to be derived.