Migrating from tsup to tsdown Knowledge base for AI agents to migrate tsup projects to tsdown — the Rolldown-powered library bundler. Runtime Requirement requires Node.js 22.18.0 or higher to run (build-time only). The bundled output can still target lower Node.js versions via the option, so a library that previously supported Node.js 18 / 20 with tsup can continue to do so after migrating. Recommended workflow when supporting Node.js 18 / 20: - Build with Node.js 22+ in CI , setting an explicit such as or . - Test the built output (or the packed tarball) on the lower Node.js versions you nee…