boot_km_ratio           Bootstrap CI for an SBW-weighted KM survival
                        ratio
get_sbws_for_study      Study-level SBW weights: closed-form first, QP
                        fallback if needed
get_weights_for_group_neg
                        Closed-form SBW group weights (negative weights
                        allowed)
get_weights_for_group_nonneg
                        Nonnegative-QP SBW group weights, with clipping
                        diagnostics
km_ratio_greenwood      Weighted KM survival ratio S1(t0)/S0(t0) with a
                        Greenwood-based CI
plot.sbw_fit            Plot covariate balance before and after SBW
                        weighting
sbw_estimate            Estimate a treatment effect from a fitted
                        'sbw_fit' object
sbw_weights             Fit stable balancing weights for a two-arm
                        study (design stage)
summary.sbw_fit         Summarize an 'sbw_fit': balance table and
                        weight diagnostics
