Your terminal. Your models. Your agent.

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.

Install Harness Star on GitHub

Open-source runtime · Node.js 22.19+ · Take a closer look

october · ~/my-projectExample

› Add a dark mode toggle to the settings page.

✳ I’ll check the theme, add the toggle, and run the tests.

readsrc/theme/tokens.ts
editsrc/settings/Appearance.tsx +24 −3
bashnpm test

Toggle added. Tests pass. Ready for your review.

›

~/my-projectaccept-editsOctober inferenceSession saved

Codex via Agent Intercom

Reviewed Appearance.tsx. Looks good to merge.

An example session: Harness reads, edits, and tests, then another agent reviews the change.

Bring the model you want

October account
ChatGPT Plus/Pro
Claude Pro/Max
GitHub Copilot
xAI
OpenRouter
Anthropic
OpenAI
Google Gemini
Amazon Bedrock
DeepSeek
Mistral
Groq
Ollama
LM Studio
vLLM

How it works

One install.
Then just ask.

Harness works in the folder you start it from. Tell it what you want, and watch each step.

Install the CLI.

One npm command. Harness needs Node.js 22.19 or newer and runs in your terminal.

Sign in and pick a model.

Run /login to use an October account, another provider account, or an API key. Then /model to choose.

Ask for the change.

Harness reads the code, edits files, runs commands, and shows each step. The session is saved so you can come back.

What it can do

A complete coding agent.
Open to read and change.

Everything from your prompt to the model request, tool calls, and saved sessions is in the public repository.

Works with other agents.

Through Agent Intercom, Harness can find other agents, send requests, pick up shared tasks, and reply to the agent that asked. A request from another agent never gives it more permissions.

Your model, your account.

Use October inference, a ChatGPT, Claude, or GitHub Copilot subscription, or an API key. Change models whenever your work changes.

Choose how much it can do.

ask checks before edits and commands. accept-edits allows edits and asks before commands. bypass, the default, allows both. These are approval controls, not a sandbox.

Sessions you can come back to.

Every session is saved on your machine. Resume it, branch from an earlier message, compact long context, or export it for review.

Script it, or embed it.

Run a one-shot prompt, stream JSON in CI, drive a long-running agent over RPC, or import the SDK into your own app.

Make it yours.

Add TypeScript extensions, skills, prompt templates, themes, and packages. Connect MCP servers through an included adapter.

MIT licensed.Read it, fork it, and change it. Built on the open-source Pi foundation.
Your terminal.Start it from any project folder. It runs with your own user permissions.
No October app needed.Harness works on its own. October Desktop is optional.
Pay only for models.The runtime is free. Model access may need a provider account or plan.

See the idea

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.

Read the docs

Ways to run it

Interactive

$ october

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

Example prompt · Pair with it in your terminal.

One-shot

$ october -p "Review this diff"

Run one task, print the answer, and exit.

JSON

$ october --mode json

Structured events for pipelines and CI.

RPC

$ october --mode rpc

Drive a persistent agent from another process.

Continue

$ october -c

Pick up your latest session in this folder.

Good to know

A few quick answers.

Read the docs Open an issue

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.

Free and open source, from October

Your next coding session starts here.

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.

In your terminal

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. Already installed? Run october update.

See model plans Read the docs

An AI coding agent.Built to work with others.