Abstract Reproducible measurement requires computational instruments whose numerical behavior remains stable across implementation variants. We establish deterministic reproducibility for Semantic-Spatial Correlation (SSC), a foundational metric in structure-meaning research, by validating three independent implementations under strict execution controls. Using condensed distance vectors, explicit seed management, and single-threaded BLAS execution, we demonstrate cross-implementation agreement at 10^(-16)precision across three distance metrics (cosine, correlation, euclidean) in 1,000trials with 64-item embeddings (dimension=128). Maximum observed difference (1.25\times 10^(-16))falls six orders of magnitude below the pre-specified tolerance (\mid\Delta\mid0). Complete code, test suite, and CI workflow are provided for third-party verification.