Paper T15B: Strain-Budget Instrumentation for Photon-Like Corridors in HLE v1 RSBU, Tail Loading, and Corridor-Internal Diagnostics

This paper introduces audit-grade instrumentation for photon-like transport in the Holosphere Lattice Engine. It measures corridor survival as explicit strain-budget usage rather than reach alone. A primary KPI, Rotational Strain Budget Utilization (RSBU), summarizes typical hop-level admissibility consumption, while companion tail metrics expose stress concentration that precedes failure. Results show corridor stability is tail-dominated: median utilization can remain moderate even as extreme hops approach or exceed budget. Preparation acts as an admissibility enabler through redistribution, not uniform strain reduction. Frequency sweeps demonstrate that permissive hit criteria do not define horizons; stability-grade readouts are required. The paper supplies the mechanical substrate for downstream coherence-horizon definitions without modifying engine rules.