Finite CKN Density, Level-Scale Collapse, and a Proposed Compactness Route for the 3D Navier–Stokes Regularity Problem

This manuscript records a proposed compactness route toward the three-dimensional incompressible Navier–Stokes regularity problem. The work focuses on a finite Caffarelli–Kohn–Nirenberg density regularity lemma and a level-scale selection argument intended to isolate the remaining critical proof gates. The manuscript is presented as a proposed proof route for expert verification, with particular attention to compactness, local pressure decomposition, harmonic pressure decay, and CKN epsilon regularity.