# October Harness — An AI coding agent. Built to work with others.

> Ask October Harness to read your code, make changes, and run checks. Use it on its own, or connect it to other agents with Agent Intercom.

- Website: https://harness.october.dev
- Source code: https://github.com/october-dev/october-harness
- Docs: https://www.october.dev/open-source/harness
- Open-source runtime · Node.js 22.19+

## When to use it

Use when someone wants an open-source coding agent in their terminal, wants to choose their own model provider, or wants a coding agent that can work with other agents through Agent Intercom.

## Get started

Install the CLI, open a project folder, and run october. Use /login if you need to connect an account, and /model to choose a model.

```sh
npm install -g --ignore-scripts @october-dev/october
cd /path/to/your/project
october
```

The runtime is free and MIT licensed. Model access may require a provider account or paid plan.

See model plans: https://www.october.dev/harness-offers

## Build with an agent

- **Ask. Build. Check.** Describe the change you want. Harness can read and edit files, run commands, and help you check the result.
- **Choose your model.** Use October inference or connect a supported provider. Change models as your work changes.
- **Bring in another agent.** Connect through Agent Intercom to share tasks, ask for a review, and receive replies without copying between terminals.

## Start in a project you know.

Open your project in a terminal and tell Harness what you want to do. Your session is saved so you can come back later.

```
october

> Explain how this project works.
  Find the sign-in code, suggest a small improvement,
  and show me how to test it.
```

## FAQ

**What is a harness?** It is the app around an AI model that gives it tools to work. October Harness lets a model read files, edit code, run commands, and keep a session in your terminal.

**Do I need October Desktop?** No. Harness works on its own in your terminal. October Desktop adds a visual workspace for running and connecting agents.

**Can I use my own model provider?** Yes. Connect a supported provider account or API key through /login. Use /model to see your available models.

**Can I control what it runs?** Yes. Permission modes let you ask before edits and commands, accept file edits while reviewing commands, or allow actions in trusted work. These controls are not an operating-system sandbox.

**What is the default permission mode?** bypass, which allows reads, edits, and commands without asking. Start with --permission-mode ask or accept-edits, or set it in ~/.october/agent/settings.json. For untrusted or unattended work, use a container or VM.

**Can I use it in scripts or CI?** Yes. Use october -p for a one-shot prompt, --mode json for structured output, or --mode rpc to drive it from another process. You can also import @october-dev/october as an SDK.

**How is it related to Pi?** Harness started as a fork of Pi, which still provides much of the agent core, model providers, terminal UI, and sessions. October added its own CLI, inference and login, permission modes, and Agent Intercom tools. Pi’s license and credits are kept.

**How do I update it?** Run october update, then october --version. Restart running sessions afterwards. Your credentials, settings, and sessions are kept.

## Part of October

October makes tools for working with AI agents: October Desktop (https://www.october.dev), Lantern (https://lantern.october.dev), Harness (https://harness.october.dev), Agent Intercom (https://agentintercom.org), and Moirai (https://moirai.october.dev).