Installation

Requirements

To get through Quickstart’s first pipeline run, you need:

• A git repository with an origin remote — scarn init reads the remote to find or create your project
• Node.js 18+ or Bun 1.3+ (or npm/pnpm/yarn — any one package manager, to install dependencies into .scarn/pipeline-builder/)
• An AI provider — the first design session connects one, and the Quickstart’s provider table says which menu entry to pick for Claude Code, Codex, or GitHub Copilot. Or export a provider API key such as ANTHROPIC_API_KEY before you start.
• A Scarn sign-in — scarn init signs you in. On a worker machine where you won’t run init, use scarn auth login.
• Docker, running where the worker runs — for steps on Runtime.devcontainer(), the default for steps that work in your code. See Runtime for which steps need it and where the devcontainer comes from.

You do not need OpenCode installed. Scarn downloads and pins its own runtime the first time it’s needed — a one-time ~100 MB download.

Install the CLI

Install the @scarn/cli package globally via npm. It installs the scarn command:

npm i -g @scarn/cli

Or with Bun:

bun add -g @scarn/cli

Verify the installation:

scarn --version

The npm package ships pre-compiled binaries for macOS, Linux, and Windows — see the full platform table in the CLI reference if you’re troubleshooting an install.

Next steps

scarn init handles signing in to Scarn and creating your project as part of setup, and the design session it hands off to connects your AI provider, so there’s no separate login step to run first. Run it from anywhere in your repository; head to Quickstart for the walkthrough.

Already signed in and just need the commands? See the CLI reference for scarn auth, environment variables, and every flag.