Geological Circumscription Index — analysis code and data artifacts

Python analysis code, data artefacts, and reproducibility materials supporting the manuscript "Quantifying tectonic–climatic circumscription: a reproducible spatial-statistical test at primary-state locations" (Zenodo DOI: 10.5281/zenodo.19722359). Contains scripts to compute the Geological Circumscription Index (GCI) from three public datasets — a plate-boundary model, a global aridity product, and a major-river network — and to reproduce all statistical tests, sensitivity analyses, and spatial-structure diagnostics reported in the paper. Includes the computed JSON output files underlying every reported statistic. All input datasets are cited with original download URLs in the README. Access is restricted during double-anonymous peer review; the record will be opened at journal acceptance.