box is an R package that provides a modern, modular module system for organizing R code into hierarchical, composable, and reusable modules. It replaces the traditional `library` and `require` functions with a declarative, explicit import syntax (`box::use`) that supports selective name attachment, aliasing, and scoped imports. The system handles both packages and local R scripts as first-class modules, supports S3 method registration, cyclic imports, interactive help, and module lifecycle hooks (`.on_load`, `.on_unload`). The architecture is built on custom environment manipulation, a PEG-like specification parser, a caching layer for loaded modules, and a small C extension for performance-critical operations. The codebase is well-structured, extensively tested, and demonstrates advanced use of R's environment and S3 dispatch mechanisms.