Claude Code for Unbuild Build Tool (2026)

Last updated: April 17, 2026

Claude Code for Unbuild Build Tool Workflow Guide

Unbuild is a modern, modular build system designed for JavaScript and TypeScript libraries. It provides a standardized way to create builds with automatic entry point generation, TypeScript support, and plugin-based extensibility. When combined with Claude Code, you can automate the entire build configuration process, from initial setup to publishing готовые пакеты.

This guide shows you how to use Claude Code to work with Unbuild efficiently, automate repetitive tasks, and create maintainable build configurations.

Understanding Unbuild Fundamentals

Unbuild uses a convention-over-configuration approach where your build behavior is defined through a build.config.ts file in your project root. The tool automatically handles:

TypeScript compilation and type declarations
Multiple output formats (ESM, CJS, DTS)
Entry point discovery and generation
Bundle optimization

Claude Code can help you scaffold new Unbuild projects, generate configuration files, and maintain build configurations over time.

Why Unbuild Over Other Build Tools?

Before diving into the workflow, it helps to understand what makes Unbuild the right choice for library authors. Unlike bundlers such as Rollup or Vite configured manually, Unbuild wraps Rollup with sensible defaults that cover 90% of library use cases without extra configuration.

Feature	Rollup (manual)	Webpack	Unbuild
Zero-config TypeScript	No	No	Yes
Auto entry discovery	No	Partial	Yes
DTS generation	Plugin	Plugin	Built-in
ESM + CJS dual output	Manual	Manual	`emitCJS: true`
Monorepo ready	Partial	Partial	Yes
Stub mode (dev)	No	No	Yes

The “stub mode” row deserves extra attention. Unbuild’s --stub flag generates a thin shim that points directly to your TypeScript source during development. This means you can link your library into a consuming app and get instant feedback without a rebuild step. a workflow that dramatically speeds up local development cycles.

Setting Up Unbuild with Claude Code

The fastest way to start a new Unbuild project is to let Claude Code scaffold it for you. Here’s a practical workflow:

Create a new directory for your library
mkdir my-awesome-library
cd my-awesome-library
Initialize with npm and install Unbuild
npm init -y
npm install -D unbuild

After this, you can ask Claude Code to generate your build.config.ts:

// build.config.ts
import { defineBuildConfig } from 'unbuild'
export default defineBuildConfig({
 entries: [
 'src/index'
 ],
 clean: true,
 declaration: true,
 rollup: {
 emitCJS: true
 }
})

Claude Code can generate this configuration automatically based on your project’s requirements. Simply describe your needs, and the AI will create the appropriate configuration.

Prompting Claude Code Effectively for Unbuild

The quality of what Claude generates depends heavily on how you phrase your request. Vague prompts produce generic configurations; specific prompts produce ready-to-ship files. Here are prompts that work well:

For a utility library:

“Create a build.config.ts for a zero-dependency utility library that needs ESM and CJS dual output, TypeScript declarations, and tree-shakable named exports. The main entry is src/index.ts and there is a separate src/cli.ts entry for a CLI tool.”

For a monorepo package:

“Generate an Unbuild config for a monorepo package at packages/core. It has peer dependencies on react and react-dom that should not be bundled. Enable strict declarations and rollup type rollup.”

For debugging a broken build:

“Here is my build.config.ts and the error output from npx unbuild. Diagnose what’s wrong and provide a corrected config.”

Pasting the error output directly into the Claude Code chat gives it the context needed to produce accurate fixes rather than generic advice.

Automating Entry Point Generation

One of Unbuild’s most powerful features is automatic entry point discovery. When you structure your project correctly, Unbuild automatically generates multiple entry points from your source files.

Recommended Project Structure

my-library/
 src/
 index.ts # Main entry
 utils/
 format.ts # Becomes /utils/format
 parse.ts # Becomes /utils/parse
 core/
 engine.ts # Becomes /core/engine
 build.config.ts
 package.json

With this structure, Unbuild automatically generates:

dist/index.js - Main entry
dist/utils/format.js - Utils formatter
dist/utils/parse.js - Utils parser
dist/core/engine.js - Core engine

You can ask Claude Code to create this structure for you:

Tell Claude: "Create a new Unbuild project with src/index.ts, src/utils/ folder, and src/core/ folder with example files"

Configuring package.json Exports Correctly

The generated dist files are only useful if package.json points to them correctly. Modern bundler resolution depends on the exports field, and getting it wrong means consumers get the wrong format or missing types. Ask Claude Code to generate the exports map alongside the build config:

{
 "name": "my-awesome-library",
 "version": "1.0.0",
 "type": "module",
 "main": "./dist/index.cjs",
 "module": "./dist/index.mjs",
 "types": "./dist/index.d.ts",
 "exports": {
 ".": {
 "import": {
 "types": "./dist/index.d.mts",
 "default": "./dist/index.mjs"
 },
 "require": {
 "types": "./dist/index.d.cts",
 "default": "./dist/index.cjs"
 }
 },
 "./utils": {
 "import": {
 "types": "./dist/utils/index.d.mts",
 "default": "./dist/utils/index.mjs"
 },
 "require": {
 "types": "./dist/utils/index.d.cts",
 "default": "./dist/utils/index.cjs"
 }
 }
 },
 "files": ["dist"]
}

This pattern. generating package.json exports alongside build.config.ts. is one of the most valuable things Claude Code can do for library authors. The dual-format exports map is tedious to write manually but critical for compatibility with both ESM-first tools like Vite and CJS-only runtimes like older Jest configs.

Using Claude Code to Maintain Build Configurations

As your library grows, your build configuration needs to evolve. Claude Code can help you:

Adding New Entry Points

When you add new modules to your library, update the build config:

// Claude: Add 'src/helpers' entry to the build config
import { defineBuildConfig } from 'unbuild'
export default defineBuildConfig({
 entries: [
 'src/index',
 'src/utils',
 'src/core',
 'src/helpers' // New entry
 ],
 clean: true,
 declaration: true,
 rollup: {
 emitCJS: true
 }
})

Configuring TypeScript Strictly

For production libraries, you want strict TypeScript settings:

import { defineBuildConfig } from 'unbuild'
export default defineBuildConfig({
 entries: [
 'src/index',
 'src/utils',
 'src/core'
 ],
 clean: true,
 declaration: {
 strict: true,
 rollupTypes: true
 },
 rollup: {
 emitCJS: true,
 inlineDependencies: false
 }
})

The rollupTypes: true option merges all .d.ts files into a single declaration file per entry. This is important for library consumers who use “go to definition” in their editors. without type rollup, they end up jumping through intermediate generated files rather than your authored source.

Handling External Dependencies

One of the most common mistakes in library builds is accidentally bundling peer dependencies. If you bundle react into your library, consumers end up with two copies of React at runtime. Ask Claude Code to audit your config:

import { defineBuildConfig } from 'unbuild'
export default defineBuildConfig({
 entries: ['src/index'],
 clean: true,
 declaration: { rollupTypes: true },
 externals: [
 'react',
 'react-dom',
 'react/jsx-runtime',
 // Add any other peer deps here
 ],
 rollup: {
 emitCJS: true,
 }
})

Claude Code can scan your package.json peerDependencies field and automatically populate the externals array for you. a tedious but critical task that’s easy to get wrong manually.

Integrating with TypeScript Projects

When your Unbuild project is part of a larger monorepo or TypeScript workspace, Claude Code can help configure proper TypeScript integration:

Ensure tsconfig.json is properly configured - Set declaration: true and declarationMap: true
Configure path mappings - Use paths in tsconfig for clean imports
Set up references - Use TypeScript project references for faster builds

A well-structured tsconfig.json for an Unbuild library looks like this:

{
 "compilerOptions": {
 "target": "ES2020",
 "module": "ESNext",
 "moduleResolution": "bundler",
 "strict": true,
 "declaration": true,
 "declarationMap": true,
 "sourceMap": true,
 "outDir": "dist",
 "rootDir": "src",
 "lib": ["ES2020"],
 "skipLibCheck": true
 },
 "include": ["src//*"],
 "exclude": ["node_modules", "dist"]
}

Note the "moduleResolution": "bundler" setting. this is the correct choice for Unbuild projects in 2026. It enables importing without file extensions and resolves exports maps in package.json, which is how most modern libraries ship.

Claude Code can audit your configuration and suggest improvements:

Ask Claude: "Audit my build.config.ts and suggest improvements for a production library"

Stub Mode for Development

One workflow improvement Claude Code can set up is a development script that uses Unbuild’s stub mode:

{
 "scripts": {
 "build": "unbuild",
 "build:stub": "unbuild --stub",
 "dev": "unbuild --stub && nodemon --watch src --ext ts,tsx --exec 'unbuild --stub'"
 }
}

With stub mode active, you can npm link your library into a consuming project and edit source files without running a full build. The stub shim re-exports from your TypeScript source via jiti (a TypeScript runtime) at development time. Claude Code can explain this workflow and set it up for your specific project structure.

Publishing Your Unbuild Package

Once your build is configured, publishing is straightforward:

Build the package
npx unbuild
Publish to npm
npm publish

Claude Code can create a release script in your package.json:

{
 "scripts": {
 "build": "unbuild",
 "prepublishOnly": "npm run build",
 "release": "np"
 }
}

Pre-publish Checklist with Claude Code

Before publishing, ask Claude Code to run through a pre-publish checklist. A good prompt is: “Check my package.json, build.config.ts, and dist/ output and tell me if anything looks wrong before I publish.”

Claude will look for common issues:

Missing or incorrect exports entries
types field pointing to a file that doesn’t exist
Peer dependencies that are also listed in dependencies (they should only be in peerDependencies)
files array that accidentally excludes dist/
Source files accidentally included in files (exposing your TypeScript source when you only want to ship compiled output)

Best Practices for Unbuild with Claude Code

Version Management

Always keep your dependencies updated. Ask Claude Code periodically to check for updates:

Tell Claude: "Check for outdated dependencies in this Unbuild project"

Test Your Build Output

Before publishing, verify your build works:

Build and test locally
npm run build
npm pack
npm install ./your-package-*.tgz

A more thorough approach is to write a small consuming script and run it with both node (which uses the CJS output) and a bundler like Vite (which uses the ESM output). Claude Code can generate this test harness for you:

// test-consumer/index.mjs . tests ESM output
import { myFunction } from 'my-awesome-library'
console.assert(typeof myFunction === 'function', 'ESM export works')
console.log('ESM import OK')
// test-consumer/index.cjs . tests CJS output
const { myFunction } = require('my-awesome-library')
console.assert(typeof myFunction === 'function', 'CJS export works')
console.log('CJS require OK')

Use GitHub Actions

Automate your CI/CD with GitHub Actions:

name: Build and Test
on: [push, pull_request]
jobs:
 build:
 runs-on: ubuntu-latest
 steps:
 - uses: actions/checkout@v4
 - uses: actions/setup-node@v4
 with:
 node-version: '20'
 - run: npm ci
 - run: npm run build
 - run: npm test

Claude Code can generate this workflow file for you automatically. For more advanced scenarios, ask Claude to add a matrix build that tests across Node 18, 20, and 22, or to add a separate job that publishes to npm only when a version tag is pushed.

Document Your Build Configuration

As build configurations grow, comments become essential. Claude Code excels at adding explanatory comments to existing configs:

import { defineBuildConfig } from 'unbuild'
export default defineBuildConfig({
 // Each entry generates a separate output chunk. useful for
 // tree-shaking in consuming apps that only import parts of the library
 entries: ['src/index', 'src/utils', 'src/core'],
 // Remove dist/ before each build to avoid stale artifacts
 clean: true,
 // rollupTypes merges all .d.ts files into a single declaration per entry
 // This is critical for clean "go to definition" behavior in editors
 declaration: {
 rollupTypes: true,
 },
 rollup: {
 // Emit a CommonJS build alongside the default ESM build
 // Required for Jest (without experimental VM modules) and older tooling
 emitCJS: true,
 // Keep peer deps out of the bundle. consumers provide their own copy
 inlineDependencies: false,
 },
})

Conclusion

Combining Claude Code with Unbuild creates a powerful workflow for JavaScript and TypeScript library development. Claude Code can scaffold projects, generate configurations, maintain build settings, and even create CI/CD workflows. allowing you to focus on writing code rather than managing build tooling.

The key insight is that Unbuild eliminates most of the manual Rollup configuration that library authors used to manage, and Claude Code eliminates the remaining friction: generating the correct package.json exports map, auditing for bundled peer dependencies, setting up stub-mode development scripts, and writing pre-publish test harnesses. Together they reduce the time from “I want to publish a library” to a correctly configured, CI-protected npm package from hours to minutes.

Start small: create a new Unbuild project, let Claude generate the initial configuration, then iterate as your library grows. The combination of AI assistance and modern tooling makes library development more accessible than ever.

Try it: Paste your error into our Error Diagnostic for an instant fix.

I'm a solo developer in Vietnam. 50K Chrome extension users. $500K+ on Upwork. 5 Claude Max subscriptions running agent fleets in parallel. These are my actual CLAUDE.md templates, orchestration configs, and prompts. Not a course. Not theory. The files I copy into every project before I write a line of code. **[See what's inside →](https://zovo.one/lifetime?utm_source=ccg&utm_medium=cta-default&utm_campaign=claude-code-for-unbuild-build-tool-workflow-guide)** $99 once. Free forever. 47/500 founding spots left.