jlrs is a Rust library that provides safe, high-performance bindings to the Julia C API, enabling both embedding Julia within Rust applications and exporting Rust functions as Julia modules (via ccall). The architecture is modular, with separate crates for raw FFI (`jl_sys`, `jlrs_sys`), a proc-macro crate (`jlrs_macros`) for derive macros and the `julia_module!` macro, and the main `jlrs` crate offering managed types (`Value`, `Array`, `DataType`), memory safety through scoped GC frames, and multiple runtime modes (local, async via tokio, multi-threaded). The library handles Julia’s garbage collector carefully with custom GC-safe locks and fast thread-local state, and supports advanced features like static arrays, ndarray integration, and opaque Rust types managed by Julia. Key entry points are the `Builder` struct for initializing Julia, runtime handles (`LocalHandle`, `AsyncHandle`, `MtHandle`), and the `julia_module!` macro for exposing Rust code. The codebase is well-tested with integration tests, benchmarks, and CI across Julia LTS and stable versions on Linux, macOS, and Windows.