Vega-Embed is a JavaScript/TypeScript library for embedding interactive Vega and Vega-Lite visualizations into web pages. It provides functions to load specs from URLs or JSON objects, apply patches, render visualizations, and add interactive UI elements for actions like exporting, viewing source, and opening in the Vega Editor. The library supports both direct DOM manipulation (via the `embed` function) and Observable notebook integration (via the `container` function). Architecture-wise, it's a modular library built with Rollup to produce both ESM and UMD formats, featuring clean separation of concerns between spec loading, processing, rendering, and UI generation. The codebase demonstrates strong engineering practices with TypeScript, comprehensive testing, and regular maintenance.