Phase-1 Companion: Photon as a Null Boundary Response of the Hydrogen Closure Domain

This record contains the Phase-1 companion paper and reproducibility package for the photon-boundary certificate in Constrained Null Geometry. The paper derives the photon as a realized null boundary response between two admissible timelike closure states: gamma = PA - PB, with gamma² = 0. A massive one-center state is treated as a timelike closure of internal null directions: nᵢ² = 0, P = sumᵢ nᵢ, and P² > 0. The photon is therefore not introduced as a particle carrying an independent trajectory. It is treated as a null boundary realization of a closure transition. The paper also distinguishes free null realization from medium-dressed optical propagation. Slow and stopped light in EIT/Bose-Einstein condensate media are interpreted as dressed boundary responses, not as a slowing of the invariant null law. The numerical certificate tests the construction on the resolved hydrogen Lyman-alpha doublet. The central 1S contact/core sector is closed by the phase-edge completion law: Lambda₁Sgeom = log (rhoₑxact / alpha) + 2 alpha / pi - K / 24. Using NIST Lyman-alpha wavelengths, the package computes photon energies, null residuals, CNG boundary energies, and PASS/FAIL certificate flags. The measured photon is certified as a null boundary response of the hydrogen CNG closure domain at the precision scale of the input wavelength table. The included ZIP archive provides a Google Colab notebook, standalone Python script, input CSV, constants JSON, generated certificate outputs, README, and SHA256 manifest.