Phase-2 Companion: Proton as a Baryonic Y3 First-Loss Closure in Constrained Null Geometry

This upload contains the Phase-2 companion article and supplementary reproducibility ZIP for the proton sector of Constrained Null Geometry. The companion removes the proton as a primitive one-center input of the Phase-2 hydrogen closure by deriving it as the lowest uud color-singlet baryonic Y3 first-loss closure of CNG. A local CNG null triad induces an open internal triplet field, whose unobservable channel basis gives the color group SU(3)c. The compact half-angle flavor projection yields the fractional charges Qu = 2/3 and Qd = -1/3, and identifies the proton as the uud color-singlet spin-1/2 baryonic closure. The proton mass is not introduced as a constituent sum 2mu + md. It is obtained from the first nonzero Y3 first-loss eigenmode and the CNG geometric baryonic radius. This gives the CNG proton mass certificate mp,CNG / me = 1836.1526580267262. The result is compared with the CODATA 2022 recommended proton-electron mass ratio, mp / me = 1836.152673426(32), giving the CODATA-aligned relative residual -8.3867 × 10^-9. The CODATA value is used only as an external comparison value, not as an input to the CNG certificate. This is a CNG-internal baryonic closure certificate, not a perturbative or lattice-QCD mass calculation. The supplementary ZIP contains the CODATA 2022-aligned reproducibility notebook, dependency audit, numerical certificate data, checksums, and source files.