Bundling with Rollup and tsup for Libraries

Vite's default configuration is optimized for applications — it bundles everything, handles assets, and generates an index.html. For a component library, you need a different output: pure ESM/CJS JavaScript files with no runtime overhead, no bundled React, and proper TypeScript declarations. Vite library mode works but Rollup and tsup are more purpose-built for this.

Rollup has been the standard bundler for JavaScript libraries for years. It produces clean, efficient output with excellent tree-shaking and supports both ESM and CJS output formats. Rollup's scope hoisting eliminates module wrapper overhead, producing the smallest possible library bundles.