The Goldilocks Geometry: Planetary Habitability as a Coupling Regime Boundary

Reframes the habitable zone concept through GCT. Habitability is determined by a system's position on the coupling surface relative to the convergence invariant (alpha=1.920) and sign-flip threshold (alpha=2.000). Four geometric channels — information, surface area, proximity, permeability — must simultaneously satisfy convergence conditions. Earth's ozone layer is identified as a zona pellucida: selective permeability membrane gating UV coupling. Venus represents a system past the sign-flip boundary; Mars lies below the coupling threshold. Extends GCT from nuclear physics through geophysics to planetary science.