Seven-Seal Spectroscopy in a Z48 Phase Bank: Floquet Scanning, Arnold Tongues, and Reactive Softening

Restricted technical note. We present a self-contained toy model and numerical checks for a noninvasive spectral probe of a constrained phase system under a strict reactive-safety condition. Technical specifics are intentionally minimized in this abstract. Revision Note (v2.0) — This update adds an “Emerald-like Spectral Signature” stress test to Appendix S, replacing the idealized isolated-line assumption with a crystal-style topology (isolated channel mode + quasi-degenerate bulk band). The scanner is re-validated under band clustering via matched windowing (pre-registered local windows) and under exact-degeneracy handling via minimal symmetry breaking. Reactive safety (K0 ± ΔK ≻ 0) remains enforced throughout. No other claims or protocol definitions are changed.