Configuration

Container naming

Containers are named md-<repo-name>-<branch-name>. Each is locked to a repo-branch pair. Repo-less containers (started outside a git repo) get random names: md-agent-<hex>.

What's inside every container

Each md container includes:

• Isolated git clone: ~/src/<repo-name> tracks a base branch matching your local branch
• User-mapped permissions: runs as your local user ID for correct file permissions
• SSH access: ssh md-<repo>-<branch> with StrictHostKeyChecking
• Preinstalled tools: full inventory
• Shell environment: PATH and env vars available in all bash invocations (interactive, non-interactive, login, and non-login)

Environment variables

Env vars reach the container through three mechanisms, merged in order:

1. .env file in your repository root: repo-specific secrets (auto-mounted)
2. ~/.config/md/env: global defaults for all your containers
3. --github flag: injects GITHUB_TOKEN at startup

# ~/.config/md/env
ANTHROPIC_API_KEY=your_key
OPENAI_API_KEY=your_key

These are merged into /home/user/.env inside the container. See Design for how this works.

GitHub token

# Option 1: environment variable
export GITHUB_TOKEN=ghp_...

# Option 2: gh CLI
gh auth login

# Then use --github flag
md start --github

The --github flag tries $GITHUB_TOKEN first, then falls back to gh auth token.

Agent configuration files

These host directories are automatically bind-mounted into each container:

• ~/.amp, ~/.claude, ~/.codex, ~/.gemini, ~/.kilocode, ~/.kimi, ~/.pi, ~/.qwen
• ~/.config/agents, ~/.config/amp, ~/.config/goose, ~/.config/opencode
• ~/.local/share/amp, ~/.local/share/goose, ~/.local/share/opencode
• ~/.local/state/opencode
• ~/.android (ADB keys)

The ~/.config/md directory is mounted read-only to prevent accidental modification of SSH keys from inside the container.

~/.config/agents is always mounted, regardless of which harnesses you use. This is the recommended place for a centralized AGENTS.md and skills directory. See Harnesses for setup instructions.

Self-hosted models

When configuring a custom LLM provider that runs on your host machine, use host.docker.internal instead of localhost. The container cannot reach localhost on your host directly.

For example, in ~/.pi/agent/models.json with Pi and llama.cpp:

{
  "providers": {
    "llama-cpp": {
      "baseUrl": "http://host.docker.internal:8081/v1",
      "api": "openai-completions",
      "apiKey": "none",
      "models": [
        {
          "id": "my-model",
          "input": ["text", "image"]
        }
      ]
    }
  }
}

This works on macOS, Linux, and Windows with Docker Desktop. On Linux without Docker Desktop, you may need to add --add-host=host.docker.internal:host-gateway to your Docker run command or configure it in your Docker daemon settings.

Build cache injection

md bakes your local build-tool caches into the container image at build time. This avoids slow cold-start downloads: the container starts with warm caches.

Caches are included only when the host directory exists; missing directories are silently skipped. The image is rebuilt when the active cache set changes, the md-user image is updated on the registry, or SSH keys change.

Default caches

Cache name	Host path	Container path
bun	~/.bun/install/cache	/home/user/.bun/install/cache
cargo	~/.cargo/registry, ~/.cargo/git	/home/user/.cargo/{registry,git}
go-mod	~/go/pkg/mod	/home/user/go/pkg/mod
gradle	~/.gradle/caches, ~/.gradle/wrapper/dists	/home/user/.gradle/{caches,wrapper/dists}
maven	~/.m2/repository	/home/user/.m2/repository
npm	~/.npm	/home/user/.npm
pip	~/.cache/pip	/home/user/.cache/pip
pnpm	~/.local/share/pnpm/store	/home/user/.local/share/pnpm/store
uv	~/.cache/uv	/home/user/.cache/uv
android-keys	~/.android (top-level files only)	/home/user/.android

md start -no-cache go-mod -no-cache cargo   # skip specific caches
md start -no-caches                           # disable all caches
md start -no-caches -cache go-mod            # only go-mod
md start -cache /path/to/my/cache:/home/user/.mycache  # custom cache
md start -cache /path/to/refdata:~/refdata:ro          # read-only, tilde path

For custom caches, append :ro to make the directory read-only inside the container. The container path may use ~ or a leading ~/, which expand to /home/user.

Mount vs. cache

--cache and --mount both bring a host directory into the container, but they behave differently:

	--cache host:container[:ro]	--mount host:container[:ro]
When applied	Build time	Runtime
Relationship to host	One-way copy baked into the image	Live bind-mount
Host changes after start	Not reflected (frozen at build)	Reflected immediately
Triggers an image rebuild	Yes, when the cache set changes	No

Use --cache for warm package-manager caches that you don't need to stay in sync with the host. Use --mount when you want the container to see host changes live, for example a shared dataset or a directory you edit on the host while an agent works. Append :ro to either for a read-only directory, and use ~ or ~/ in the container path to mean /home/user.

md start --mount ~/datasets:~/datasets        # live, read-write
md start --mount ~/secrets:~/secrets:ro       # live, read-only

GitHub authentication inside the container

The container does not have access to your host GitHub credentials. To authenticate from inside:

gh auth login

Or use md start --github to inject GITHUB_TOKEN at startup.

Chrome/Chromium

Chrome and Chromium are preinstalled with initial preferences configured for a clean first-run experience. md handles the required security options automatically so Chrome's sandbox works inside the container.