Fixed risk_pred no longer raises UnboundLocalError when inputs for multiple models are supplied at once. Model selection is now resolved a single time with an explicit 8 > 6 > 4 precedence, so the coefficient block and the risk-score adjustment always agree on the chosen model. RiskPredictor.predict_kfre now validates num_vars and raises ValueError for unsupported values (e.g. num_vars=5) instead of falling through and returning None. Unrecognized or missing sex values are no longer silently coerced to female in the batch paths (upcr_uacr, RiskPredictor.predict_kfre). Recognized values are matched case-insensitively (female/f, male/m); unrecognized non-empty values raise a warning and yield NaN. Non-positive uACR values are no longer silently clamped to 1e-6. A non-positive scalar uACR now raises ValueError; in batch inputs, offending rows are set to NaN with a warning. Corrected the direction described in the perform_conversions comments and docstring (the conversion factors themselves were already correct and are unchanged), and documented the single-pass scope of convert_all. Added bootstrap_metric_ci: bootstrap confidence intervals for any supported metric (auc_roc, average_precision, precision, sensitivity, specificity, brier), with reproducible resampling via seed and a progress bar over resamples. Out-of-bounds covariate warnings in risk_pred: a UserWarning is emitted when covariates fall outside broad, physiologically plausible ranges for the KFRE's intended population (adults, CKD stages G3-G5). Predictions are still returned. Applies to all public entry points. censor_incomplete option on class_esrd_outcome: when True, non-event patients whose follow-up ends before the horizon are labeled NaN (censored) rather than 0, so right-censored patients can be excluded from fixed-horizon evaluation. Defaults to False to preserve existing behavior. uPCR-to-uACR approximation disclaimer: upcr_uacr now documents that the conversion is an approximation without universal consensus and emits a one-time UserWarning when it produces estimated values. Explicit num_vars override on risk_pred to force a specific model variant (4, 6, or 8) regardless of which optional inputs are present. Regression test suites for input validation, out-of-bounds warnings, and bootstrap confidence intervals. Changed Corrected docstring and README wording to consistently describe estimating the risk of kidney failure in patients with CKD, rather than "CKD development" or "CKD progression." class_esrd_outcome documentation corrected: the event indicator is a user-supplied dialysis/transplantation (kidney replacement therapy / ESKD) flag; the function applies a time window to it and does not derive the event from eGFR. Serum measurements labeled explicitly for albumin, phosphorous, bicarbonate, and calcium in the parameter documentation. Dependencies Added tqdm (>= 4.0) as a dependency, now used for the bootstrap_metric_ci progress bar. (It had been removed in 0.1.16.) Notes No KFRE coefficients or baseline survival values were changed. Risk estimates for valid inputs are identical to 0.1.17.