The Great Merger: Cascade Genesis and Terminal Third-Throat Formation in a Regular Six-Throat Spacetime

We present a Genesis pathway for the regular six throat spacetime developed in Papers I through VIII. A cold positive energy cosmic smoke with density perturbations defines the physical initial state and two dominant primordial bodies undergo the Great Merger that establishes the central Zero Region and the two directed branches. A systematic support sector analysis excludes static radial scalar routes through exact chamber identities. Temporal scalar hair opens a quadratic DHOST Class Ia branch above an analytic threshold. High precision reconstruction then identifies two finite stationary support loss and re entry sectors that straddle the second and third throats. The third transition completes inside the seventh layer collar and the third throat is terminal. The completed construction contains exactly six throats and fourteen directed layers with no fourth throat and no eighth layer. The accompanying reproducibility bundle recomputes the compatibility discriminant and all four transition roots from the exact determinant and includes symbolic and numerical certification programs.