`esbuild-extra` is a lightweight package that extends esbuild plugins with additional features like `onTransform` hooks for cooperative file transformation, `onResolved` hooks for path resolution manipulation, and methods for dynamic file loading and emission. It's designed as a smaller alternative to `@chialab/esbuild-rna` for build tools and plugin developers who want to enhance esbuild's capabilities without the overhead of larger dependencies. The package is ideal for developers working with esbuild who need more control over file transformations and build processes.