GCFT-0712: Quiet Oscillations, Radiation Zeros and Harmonic Leakage

A localized oscillating source can generate a substantial near-field response while having a vanishing projection onto outgoing radiation modes. We investigate this distinction in a specified neutral two-field coherence model. For a prescribed carrier, we establish an equality between interaction work and outgoing massive-wave power, construct a smooth positive radial source with an exact second-harmonic radiation zero, and derive an inverse-duration energy-leakage law for temporally localized forcing under stated hypotheses. We examine persistence under short-range radial operator perturbations and a spatial-phase obstruction. Six finite-time numerical branches of an existing spherical Einstein-scalar evolution provide a bounded comparison. Small higher harmonics substantially influence the surviving source overlap after spatial cancellation. Analytical results apply under their stated comparison-model assumptions. Exact dynamical zero selection, curved outgoing loss estimates, continuum error bounds, nonlinear stability and asymptotic lifetime remain unestablished. Version 1.0 preprint. Academic Art and Dark Art editions contain identical scientific content and share this DOI. A source and supporting-data archive accompanies the PDFs; its README distinguishes the included reproducible calculation from historical provenance dependencies. No independent external validation of the numerical libraries or a uniquely native GCFT action is claimed.