Particle Structure from Codimension-Two Carrier Closure

The Standard Model describes particle phenomena through continuous gauge structures, chiral assignments, color, generations, and Yukawa masses, but it does not derive these labels from a deeper structural principle. This paper proposes a carrier-resolution interpretation in which particle species are not separate primitive objects, but different carrier-readable manifestations of one loop-detectable codimension-two archetype defect. The carrier supplies Lorentzian propagation and globally available \(U(1)\) phase closure, while particle labels arise through holonomy, embedding, closure, and saturation conditions. The framework argues that local \(U(1)\) closure favors a neutral-parent starting point, whose persistent asymmetric resolution is modeled as \[P_0\longrightarrow Z_2\oplus (Z_2\!\rightarrow\!Z_3).\] The \(Z_2\) branch is interpreted as lepton-like after Lorentz embedding, whereas the \(Z_2\!\rightarrow\!Z_3\) branch supports a nested confined \(Z_3\) monodromy interpreted as hadronic structure. Incomplete \(Z_3\) sectors are not carrier-readable as isolated hadrons; the usual \(SU(3)_C\) QCD description is retained as the effective high-energy continuum envelope of temporarily resolved \(Z_3\) sectorality. The paper further gives a conditional interpretation of the three observed generations as leading saturation modes of the dominant \(U(1)/Z_2/Z_3\) closure backbone, while higher \(Z_n\) refinements appear as suppressed response corrections rather than ordinary additional generations. As a concrete test, the neutron--proton magnetic-moment ratio is derived from an ideal \(Z_3\)-complete baseline and a rule-generated interface sequence through \(Z_7\). The successive predictions improve from the \(10^{-4}\) level to the few-ppm level and then to below one ppm of observation, without introducing new particles, new fundamental interactions, or fitted coefficients.