Magnetic Quantization and Landau Levels as Structural Selection

In this paper, we argue that Landau quantization arises not from magnetic force as a generator of structure, but from structural selection imposed by geometric constraint. The magnetic field restricts admissible motion in the transverse plane, producing closed trajectories that admit only a discrete set of compatible phase-space configurations. Quantization follows from this restriction alone. Forces act only to maintain the constraint and to stabilize motion within it. This reframing places magnetic quantization squarely within a structure-first hierarchy: geometry determines admissibility; selection resolves allowed states; dynamics and forces operate downstream as enforcing agents. This work builds on and complements two companion contributions in the structure-first framework. In Structure Before Force: Harmonic Eigenmodes as Primary Constraints, we established that geometry and boundary conditions define the space of admissible configurations prior to dynamical or force-based descriptions. In Structural Selection: How Geometry Determines Admissible Physical States, structural selection was formalized as the mechanism by which admissible states are resolved without invoking force. In a related experimental instantiation, The Zeeman Effect as Evidence for Structure Before Force (DOI: 10.5281/zenodo.18143570) demonstrates that spectral splitting under a magnetic field does not create new state space but resolves pre-existing admissible internal configurations. Together, these works form a coherent trilogy showing that forces act only within structural constraints already determined by geometry.This record includes an accompanying framework overview file that provides reading context and scope clarification for the associated technical paper. The overview introduces no new claims and is included to guide interpretation and navigation of related works.