Library builds - build-preset

libraryBuild({ name, ... }) returns a tsup Options object. It needs the optional tsup peer (^8.5.0).

// tsup.config.ts
import { libraryBuild } from "build-preset/tsup";

export default libraryBuild({
  name: "@your-scope/renderer",
  external: ["three", "react"],
});

The banner is derived from name, so it cannot drift from the package it describes. The defaults are ESM, es2022, declarations, sourcemaps, treeshaking and keepNames (so consumer stack traces and fn.name checks stay meaningful), with no minification, because applications minify and libraries should not.

`external`

external is the setting that matters. Anything imported but absent from it gets bundled into dist, which duplicates the dependency and breaks instanceof against the host's copy. List your peerDependencies.

JSX

libraryBuild({ name: "@your-scope/ui", jsx: "automatic" });

The mode is routed through esbuildOptions, because tsup's Options has no jsx field and a top-level jsx in a hand-written config is silently discarded. Use "preserve" only when your entry points also resolve to .jsx files; esbuild will not put preserved JSX in a .js file.

Escape hatch

overrides merges last and wins:

libraryBuild({
  name: "@your-scope/mobile",
  overrides: { target: "es2020", splitting: true },
});

With splitting on, the banner lands in the chunks that carry code rather than in the re-export shim at index.js. The /tsup entry point is not part of the package barrel, so projects that do not build a library never load tsup types.