D72e — Non-circular emergence of the gravitational constant from the fine-structure constant: the parity-leakage cascade α_G = [α(1+δ)]^18 and the sealed predictive architecture

This document (D72e of the PDL framework) consolidates the verification campaign v25–v54 of the D72 interface-asymmetry work package. It establishes that the fine-structure constant α and Newton's gravitational constant G are two expressions of a single mean boundary-leakage parameter ε, related by the cascade α_G = [α(1+δ)]^18, and that the long-standing circularity on G is broken by architecture: a sealed predictive pipeline deprived of any G input produces the frozen prediction G_pred = 6.6743264×10⁻¹¹ m³ kg⁻¹ s⁻², judged a posteriori by the external arbiter G_CODATA with agreement +3.96 ppm (+0.18σ). The document records the complete derivation chain (STRUCT → α⁻¹ = 137 + 33/917 → mixing fraction x = 7/12 via three independent geometric routes → δ = 3.0429555% → ε → α_G → G_pred), the register of 23 cleanly closed null gates with multiplicity controls, and the honest reservations: ~20% chance coincidence until the pre-registered falsifier (d_r = 0.04795969 and f = 0.157126, simultaneously) is closed; the missing radial dressing of the 918-site graph; the reading (not derivation) status of x = 7/12 and 1/133.