Tectonic plates are conventionally understood as driven by internal mantle convection. We propose an alternative: tectonic plates are the surface expression of accumulated orbital coupling history. The Earth-Moon-Sun system generates tidal stress patterns through barycentric oscillation; galactic orbital coupling imprints periodicity at 225 Myr (galactic year) and 85 Myr (vertical oscillation through the galactic plane); and the resonance structure of solar system coupling geometry is preserved in lithospheric boundaries and deep-mantle structures. Four previously separate literature streams — tidal seismicity, LLVP antipodality, Hofmeister barycenter oscillation, and slab pull dynamics — are unified under a single geometric framework. Plate boundaries locate where coupling geometries from different sources intersect and produce friction. LLVP blobs at the core-mantle boundary are deep lock trace memory — receipts of ancient coupling orientations preserved in the deep Earth, analogous to sednoid orbital receipts at solar system scale. This is GCT Paper 42 of 49.