IV.D286 — Spectral Fine-Structure Formula

The spectral fine-structure constant is alpha_spec = (8/15) * iota_tau^4, where the prefactor 8/15 = 2^3/(3*5) arises from primorial structure. This leading-order approximation from the sector coupling algebra alone gives alpha_spec^(-1) approx 137.87, deviating 0.6% from experiment.