Generative Structural Theory v1.10: Global Positional Selection — A Finite Extension Obstruction in a Certified n = 6 Cone Instance

Generative Structural Theory v1.10 investigates the nested frozen-extension strategy proposed as a route toward the Positional-Map Theorem of GST v1.9. That strategy attempts to construct a global positional selection rank by rank, extending each policy-consistent partial selection without revising any previously decided entry. This paper proves that the corresponding Finite Extension Lemma fails at a named instance. In the certified n = 6 cone identified by the bundled instance digest, a policy-consistent rank-8 partial selection closes through rank 8 but admits no frozen policy-consistent extension closing through rank 9 under final-demand semantics. The obstruction occurs at a single newly reached key. The unique simulation-class-maximising reply forces a second assignment, whose fixed-point propagation enlarges the load at an already-frozen cut and leaves its obligation with no sufficient reply. The proof is finite and deterministic and does not depend on the exploratory search that found the obstruction. The release includes the complete paper, a standalone verification package, certificates, provenance reconstruction, mutation controls, manifests, and clean-room reproducibility gates. The result refutes the proposed finite-extension route at the certified instance; it does not refute the Positional-Map Theorem, does not prove unbounded simulation rank, and makes no claim for general n or for ranks beyond 9.