open-harness/docs/quickstart.md

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3	Quickstart

Quickstart

This guide takes you from zero to a running sandbox with an interactive shell in under five minutes. The only host dependency is Docker.

Before you start

Install Docker with the Compose plugin: docs.docker.com/get-docker. Everything else runs inside the container.

Install

curl -fsSL https://oh.mifune.dev/install.sh | bash

The installer clones into ~/.openharness, prompts to share your host gh token, writes .devcontainer/.env with safe defaults, and brings the sandbox up via docker compose.

Enter the sandbox

Recommended: attach with VS Code's Dev Containers extension. Works identically whether the sandbox is on your laptop or on a remote host you're SSH'd into (with VS Code's Remote-SSH extension). One window, your normal editor, integrated terminal, file tree — the most consistent and productive setup across environments.

1. Install the Dev Containers extension.
2. Open the Command Palette with Ctrl+Shift+P (Cmd+Shift+P on macOS) → Dev Containers: Attach to Running Container... → select openharness.
3. When the new VS Code window opens, set the workspace folder to /home/sandbox/harness.

Terminal fallback for when VS Code isn't available or you just need a shell:

cd ~/.openharness
make shell

Either way you're inside the isolated sandbox as the sandbox user. Working directory: /home/sandbox/harness.

Pick your harness

The sandbox ships with Claude Code, Codex, OpenCode, Pi, and DeepAgents preinstalled, plus T3 Code on demand via npx. Authenticate at least one before use:

• Claude Code: run claude and follow the OAuth prompt
• Codex: run codex login
• OpenCode: run opencode auth login
• Pi: configure provider keys via environment variables
• DeepAgents: write provider keys to ~/.deepagents/.env
• T3 Code: authenticate one of Claude / Codex / OpenCode, then npx t3 (browser UI on port 3773)

Claude Code remains the documented default. See the harnesses overview for the full list and per-harness setup.

Connecting to the Sandbox

If GH_TOKEN was set during install, the entrypoint already ran gh auth login and gh auth setup-git for you. Otherwise run them once inside the shell:

gh auth login && gh auth setup-git

Configuration

.devcontainer/.env is the single customization surface — generated with safe defaults during install. The most-edited values:

Var	Purpose
SANDBOX_NAME	Container/compose project name
GH_TOKEN	GitHub token for non-interactive auth
TZ	Container timezone
INSTALL_AGENT_BROWSER	Set true to install Chromium (~1 GB)

Apply changes with make destroy && make sandbox.

For additional services, the base ships with an opt-in Postgres overlay at .devcontainer/docker-compose.postgres.yml; for anything else (tunnels, reverse proxies), register your own compose overlay by appending it to composeOverrides[] in config.json.

Next steps

With the sandbox running, here's what to wire up next:

• Slack bridge for your sandbox agent → integrations/slack.md
• GitHub auth (only if you skipped GH_TOKEN at install) → integrations/github.md
• Postgres via Compose overlay → integrations/postgres.md

Tear down

When you're finished, exit the shell and clean up from the host:

make destroy

This stops the container and removes its volumes. To keep auth credentials across rebuilds, stop without removing volumes:

make stop

Bring it back later with make sandbox.