Bun CLI

Bun is an all-in-one JavaScript/TypeScript runtime, package manager, bundler, and test runner. Bun runs TypeScript natively — bun file.ts directly, no compile step, no tsc, no ts-node. Always use bun instead of node, npm, npx, yarn, or pnpm in Bun projects.

Detecting Bun Projects

A project uses Bun if any of these are present:

• bun.lock or bun.lockb in the project root
• bunfig.toml in the project root
• bun field in package.json (e.g., "bun": { "install": { ... } })
• Package manager field: "packageManager": "bun@..."
• [run] bun = true in bunfig.toml (forces Bun runtime for all scripts)

Critical Rule

In a Bun project, ALWAYS use bun for everything. Never fall back to node, npm, npx, yarn, or pnpm. This avoids compatibility issues, unnecessary retries, and cryptic errors from Node.js/npm not understanding Bun-specific features (workspace protocol, lockfile format, trustedDependencies, etc.).