Product-Volume Xi: A Strain Framework for Cadence-Dependent Alpha Residuals

This work presents an internally constrained effective model for cadence-dependent alpha-sector residuals. The framework introduces a product-volume strain coordinate (Xi), an electromagnetic interface projection (P_alpha = 1/H), and a duality-constrained interface hierarchy that selects H ≈ 150 through reciprocal failure-mode balance. The model is not presented as a final theory. It includes explicit failure modes, parameter sensitivities, and falsifiable predictions, particularly in atomic clock network residuals under realistic instrument response. The purpose of this release is to invite external critique and stress-testing of the internal constraint chain.