ts-library

ts-library is a guidance skill for authoring high-quality TypeScript libraries and npm packages, with patterns extracted from studying projects such as unocss, shiki, unplugin, vite, vitest, vueuse, zod, trpc, and drizzle-orm. It solves the recurring problems of setting up a new library project, configuring package.json exports for dual CJS/ESM output, choosing and configuring build tooling, designing type-safe public APIs, writing advanced TypeScript types, testing, and publishing to npm. It is organized so the agent loads only the reference files relevant to the current task rather than everything at once.

The skill centers on a New Library Workflow: create the project structure, configure package.json exports, set up the build with tsdown, verify the build with pnpm build && pnpm pack --dry-run (checking that output includes .mjs, .cjs, and .d.ts), add tests, and configure release. A Quick Reference table maps tasks to on-demand reference files including references/project-setup.md, references/package-exports.md, references/typescript-config.md, references/build-tooling.md, references/eslint-config.md, references/api-design.md, references/type-patterns.md, references/testing.md, references/release.md, and references/ci-workflows.md. It ships quick-start snippets for a minimal package.json (with exports, main, module, types, and files fields) and a tsdown.config.ts using defineConfig with entry, format ['esm','cjs'], and dts: true. Key principles include ESM-first with "type": "module" and .mjs outputs, always supporting both CJS and ESM, moduleResolution: "Bundler", using tsdown for most builds and unbuild for complex cases, smart defaults over forced config, and tree-shakeable output via lazy getters and sideEffects: false.

Target users are developers building single-package or monorepo TypeScript libraries who need consistent, modern conventions for bundling, dual-format output, API design patterns (builder, factory, plugin), advanced type inference, vitest-based testing, and release/CI workflows. The skill notes that for Nuxt module development the separate nuxt-modules skill should be used instead. It is explicitly token-efficient, with the main skill around 300 tokens and each reference roughly 800-1200 tokens, and instructs the agent not to load all files at once.