Surrogate Evaluation for Jointly Longitudinal Outcome and Surrogate // Tools for surrogate evaluation in longitudinal studies using state-space models as proposed in Santos Jr. and Parast (2026)doi:10.48550/arXiv.2604.12882. The package estimates treatment effects over time with and without adjustment for surrogate information, summarizes the proportion of treatment effect explained by a longitudinal surrogate, quantifies uncertainty via bootstrap resampling, and provides plotting and summary utilities for fitted models.