Quantum Threshold Boundary (QTB): The Record-Threshold Interface of the SST/UPF Quantum Sector

We introduce the Quantum Threshold Boundary (QTB), the record interface of the SST/UPF quantum sector: the boundary at which unresolved support structure below one tick of a Sub-Structure (SbS) enters that SbS as coherent quantum amplitude, and at which closed, persistent lattice configurations register as classical recorded events. The paper consolidates the 2026 p2 polarization/qubit quantum-kernel program into three verified components: GQ1, which establishes the wall theorems, Nyquist floor, and record bottleneck; GQ2, which reconstructs the p2 qubit using the corpus-native polarization continuum together with the Z₂₄ token-phase layer, recovering lattice-exact optical elements, Born-rule uniqueness, anti-unitary time reversal, and the discrete-family no-go; and GQ3, which makes the finite support anchor explicit and recovers Tsirelson-bounded Bell correlations, exact no-signaling, the classical CHSH ≤ 2 control, and the identity CHSH_full = 2√(1+C²). Within the QTB p2 construction, the remaining quantum input is localized to one interface postulate, DV-ψ: each level-n tick delivers the coherent sum of the amplitudes of its support-class members. DV-ψ is formulated here but not adopted into the SST/UPF corpus; the prior canonical-quantization postulate remains formally in force. The framework also carries quantitative falsification hooks, including the finite-support Born-deviation budget δ(N), the support-symmetry defect law, and the structural prediction that the finite anchor contributes no source-side deviation from standard quantum predictions. Verification This record includes the QTB Verification Package v1.0, containing independently rerunnable computational checks for the numerical and enumerative results reported in the manuscript. This manuscript is a preprint and has not been peer reviewed. Related works Structured Space Theory (SST) — Concept DOI (all versions): 10.5281/zenodo.17154635Unified Pattern Framework (UPF) — Concept DOI (all versions): 10.5281/zenodo.17900824Mathematical Foundations of SST — Concept DOI (all versions): 10.5281/zenodo.19080506 License CC BY-NC-ND 4.0