1. Multi-provider. Astra, Fable, and Grok in one app, each with its vendor's own prompts and tools. Give every task the model that fits, and delegate to subagents on any of them.
2. Reuse your subscriptions. Sign in with the Claude, Codex, and Grok subscriptions you already pay for. Happy adds a harness, not another bill.
3. Open source MIT. It runs on your own hardware and your projects stay ordinary folders. Read the code, fork it, ship your own build.
4. End-to-end encrypted mobile app. Left your desk? The same sessions are already on your phone, and what moves between your devices is encrypted.
5. Natively multiplayer. Invite a colleague or a friend into the session. You both watch the same agent work, and either of you can steer it.

Website · Documentation · Discord · Development guide · MIT License

The original CLI wraps the Claude Code and Codex harnesses directly in your terminal and lets you continue from your phone.

For multi-model sessions and teams, move to the desktop app and Happy Harness.

npm install -g happy

# Start Claude Code
happy claude

# Or start Codex
happy codex