Geometric Origin of Back-Reaction Positivity in the COCM

The conditional derivation of orbital ellipticity in NT6 reduces to a single open hypothesis: the back-reaction amplitude deltaᵧ > 0. This note investigates whether deltaᵧ > 0 can be derived from the bulk geometry. The central argument is that the tension asymmetry tauC0 >> tauRn breaks the symmetry deltaᵧ -> -deltaᵧ in the effective orbital potential, generating a negative linear term that displaces the equilibrium from deltaᵧ = 0 to deltaᵧ* > 0. Under four explicit geometric hypotheses G1-G4 (distinct from H1-H3 of NT6), the equilibrium satisfies deltaᵧ* > 0. Under G1-G4, the chain deltaᵧ* > 0 -> J > 0 -> e > 0 is grounded in the bulk geometry. The remaining open sub-problem is G3: the stability of the displacement mode (mₑff² > 0).