What is Phantom?

Phantom is a CLI tool for managing overlay filesystems to enable multiple AI agents to work on the same codebase in parallel without conflicts. Each agent gets its own isolated overlay with independent writes and its own git branch.

Quick Start

If you haven’t installed Phantom yet, follow the Installation guide.

Once installed, initialize your configuration:

phantom init

This creates a default configuration file at ~/.phantom/config.yaml.

Basic Workflow

1. Create an overlay and run an agent

   phantom run ~/myproject --agent "claude --print" --task "implement auth" --name auth-feature
   

2. Check what changed

   phantom diff auth-feature
   

3. Apply changes back to the base repository

   phantom apply auth-feature --cleanup
   

Core Concepts

Overlays

An overlay is a writable filesystem layer on top of your base project directory. The base stays untouched — all writes go to an isolated upper layer. Each overlay gets:

• A unique mount point (e.g., ~/.phantom/mnt/feature-auth/)
• An isolated git branch (e.g., phantom/feature-auth)
• Its own state and configuration

Agents

An agent is any CLI command that can modify files in a project. Common examples include:

• claude --print - Claude Code CLI
• aider - Aider AI pair programmer
• gemini - Gemini CLI
• copilot - GitHub Copilot CLI

Workflows

Phantom supports three main workflow patterns:

• Single Agent (run) - Run one agent on a task
• Parallel Agents (run-all) - Run multiple agents simultaneously on the same base
• Sequential Chain (run-chain) - Run agents in sequence, each building on the previous

Documentation Sections

Explore the documentation to learn more about Phantom’s capabilities:

• Commands Reference - Every command, flag, and option
• Workflows & Examples - Real-world usage patterns
• Configuration - Config file, hooks, templates, environment variables

How It Works

Base Directory (read-only lower layer)
         ↓
   ┌─────────────┐
   │  Overlay A   │  → phantom/feature-auth  → ~/.phantom/mnt/feature-auth/
   │  Overlay B   │  → phantom/feature-api   → ~/.phantom/mnt/feature-api/
   │  Overlay C   │  → phantom/feature-tests → ~/.phantom/mnt/feature-tests/
   └─────────────┘
         ↑
  Isolated upper layers (~/.phantom/overlays/<name>/upper/)

Linux: Native kernel overlayfs (root) or fuse-overlayfs (rootless, auto-detected).

macOS: unionfs-fuse via macFUSE or FUSE-T.

Need Help?

• Report an issue on GitHub
• Check the FAQ for common questions