Kurbo is a Rust library for 2D vector geometry, primarily used in the Linebender ecosystem (e.g., the Vello rendering engine). It provides core geometric types such as BezPath, PathSeg, curves (cubic, quadratic, arc), affine transforms, and advanced algorithms for offset, stroke expansion, curve fitting, flattening, and polynomial root-finding. The architecture is a Cargo workspace with two crates: `kurbo` (main geometry library) and `polycool` (polynomial utilities). Key entry points include the `BezPath` builder, `ParamCurve` traits for generic curve operations, and high-level functions like `expand_path`, `stroke`, and `fit_to_bezpath`. External dependencies are optional (serde, euclid, mint, schemars) and the library supports no_std via the `libm` feature. Data flows involve constructing paths from elements, applying transformations, and then processing them for rendering or analysis. The codebase demonstrates strong numerical methods, trait-based abstractions, and careful handling of edge cases, making it a high-quality foundation for vector graphics applications.