String Theory Constraint Structure: A Two-Boundary Inference Diagnostic

This technical note applies Two-Boundary Inference (TBI) and the Relational Thermodynamic Layered Index (RTLI) as diagnostic tools to a broad class of structured physical systems, including exoplanet architectures, galaxy dynamics, the cosmic microwave background, quantum coherence experiments, atmospheric chemistry, and string theory. Rather than modeling forward trajectories, the framework analyzes constraint topology: how observed states arise as survivors of selection between generative and observational boundaries. Three diagnostics are emphasized: compression-without-collapse (variance suppression with preserved distinctions), null-space asymmetry (directional selection at constraint boundaries), and coherence thresholds separating loosely constrained from tightly constrained regimes. Across empirically accessible domains, the analysis shows that physically persistent systems exhibit strong variance compression while encoding information in relational quantities (ratios, phase relationships, correlations) rather than absolute values. Application to string theory is explicitly diagnostic and non-predictive: rigid consistency conditions (anomaly cancellation, modular invariance, dualities) indicate a survivor-conditioned structure with asymmetric boundaries, but quantitative RTLI metrics cannot be computed due to the lack of observable access to the generative boundary. The note reframes degeneracy, model disagreement, and residual scatter not as noise but as information about constraint softness and phase boundaries, offering a unifying methodological lens across scales. No new physical laws or models are proposed; the contribution is a reusable analytical framework for interpreting structured data in constraint-dominated systems.