Unified Balance-Line (UBL) ⊥ Directive Handoff (DHP) with Falsifiable Fingerprints: A Cross-Platform Mapping for Magnons, L1/L2, OAM, and SRO_Floquet

Believed to be a first: a single, preregistered, falsifiable workflow that unifies four experimental platforms—magnonics (including time-varying strong coupling with time-diffraction combs), L1/L2 orbital families, optical OAM ring optics, and SRO/Floquet plateaus—under one grammar. The stack has three layers: Unified Balance-Line (UBL) for locating flat windows (R ⁣≈ ⁣1, F ⁣≤ ⁣Fmax⁡); Directive Handoff Protocol (DHP) for safe, causality-preserving motion via preregistered cuts; and Fingerprints for proof by failure, with platform-specific disable-LLL and flip-only ZZZ tests. We specify acceptance lines (flatness, odd-null centering, gap openness, sign⁡\operatorname{sign}sign reversal, protocol invariance) and ship a bench-run card and log schema so results produce pass/fail calls rather than opinions. In magnons, new edge-based handoffs and comb metrics drop in without changing UBL geometry, aligning with recent demonstrations of time-varying strong coupling and double-slit time diffraction (Rao et al., 2024; Phys.org feature, 2025). The deliverable is a portable spec with preregistered thresholds and minimal experiments that labs can replicate across platforms.