Data and code for: The intrinsic isotopic diversity of presolar silicon carbide is smaller than its measured spread implies

Self-contained reproducibility package for a measurement-error-aware analysis of 20,502 presolar silicon carbide grains compiled in the Presolar Grain Database. It includes an exact copy of the official 2026-05-19 CC0 source CSV; a probabilistic per-grain source catalog for all 18,864 grains with both silicon isotope ratios, with eight finite normalized source probabilities per grain; source values for every figure and table; archived numerical results, including five-initialization catalog sensitivity, an independent 32-versus-64-restart classifier comparison, a retained low-budget diagnostic, and CPU/CUDA catalog checks; complete analysis and verification code; exact tested-environment and minimum dependency specifications; licenses; a 138-check numerical audit; and an independent package-integrity audit.