Fine-Structure Closure from One Topological Mode and One Global Scalar

Fine-Structure Closure from One Topological Mode and One Global Scalar is a direct continuation of Five Papers on Constrained Null Geometry and of the companion article Protected Topology, Boundary, and Domain in Constrained Null Geometry. The paper isolates the fine-structure axis of constrained null geometry and shows that it closes as a rigid operator-topological chain. On the closed axis, the global boundary/topological architecture reduces to one topological mode and one signed scalar. This reduction determines an exact growth bridge, a unique internal closure coordinate, and a fine-structure micro tower. The local interface remainder closes by a dyadic quartic law, and the local alpha-response decomposes into symmetric, odd, and even parts. The paper argues that the fine-structure sector is not an added subsystem, but a necessary internal sector of the same operator-topological geometry. On the closed axis, the 137-target remains certified