A second Mac as a host

A second Mac — the desktop under your desk, a Mac mini in a cupboard, a machine at the office — makes a good host. It has the horsepower, it never travels, and its lid is never closed on it.

Unlike This Mac, this path starts over SSH, so the remote machine has to let you in once.

On the remote Mac

1. Enable Remote Login: System Settings › General › Sharing › Remote Login.
2. Make sure it is reachable from your Mac — same network, a tailnet, or a routable address.
3. Everything from Prerequisites applies to it: Apple Silicon, macOS 14+, Command Line Tools, tmux, at least one agent CLI installed and logged in under the user you will connect as.

In the app

Add Remote Host…, then give the address and the user. You can authenticate with a password or an SSH key.

Offsite probes the machine, installs its host components into that user’s ~/.offsite, and starts the agent. From then on your devices talk to the embedded agent, not to the system sshd — the initial Remote Login was for the install.

Caution

The agent CLIs must be logged in as the host user, not as you on your laptop. A claude that is authenticated in your local terminal tells you nothing about the remote machine. This is the single most common reason a fresh remote host has a healthy tmux and no working agent.

Root versus a normal user

Prefer a normal user account with sudo over root:

• Claude Code refuses --dangerously-skip-permissions when running as root, so the YOLO permission mode is unavailable there.
• Everything Offsite installs lands in that user’s home directory, which keeps the blast radius small.

Details

• All bootstrap probes run with BatchMode=yes and short connect timeouts, so a machine that wants an interactive password fails fast instead of hanging.
• Probe output is parsed as key=value, never as prose — a noisy login shell that prints a banner does not break setup. One known exception is the architecture probe; a .zprofile that echoes before returning can confuse it.
• Sessions on a remote Mac behave exactly like local ones: host-owned tmux, survive disconnect and reboot, restored with the CLI’s own resume.
• Deploy-to-phone and Computer Use are tied to the host machine: an iOS build runs on the host’s Xcode, and Computer Use drives the host’s screen.