Why I turned my old MacBook into a server for coding agents

Async coding agents need a host. Mine is called Ferris, and it shipped speq-skill v0.3.0 to GitHub on its own while I was away from my desk.

This is the first post in a series on getting coding agents to work for me asynchronously. The article walks through installing Debian on an old Mac, getting Claude Code and Codex signed in over XRDP, and the three use cases I run on Ferris today.

Building Ferris#

Ferris is my old 15“ Retina MacBook Pro. It was my favorite laptop and partner in crime for over five years until we parted ways for a newer MacBook Pro. Since then it has been sitting in my drawer without a purpose. The specs are (roughly): Intel Core i7 at 2.50 GHz, 16 GB RAM, NVidia graphics with 2 GB NVRAM.

When I read about all the people running OpenClaw or other agents on tiny VMs in the cloud, I thought: “Ferris still has ample power for Claude Code or Codex”. I run LLMs in the cloud via Anthropic or OpenAI, so the heavy thinking happens in the cloud anyway. Ferris only has to handle file operations and, of course, compiling.

I started by installing Debian 13 “trixie”. The process was straightforward:

1. Download a live install image. I went with Live Xfce amd64.
2. Still on macOS, flash an old USB stick using balenaEtcher.
3. Reboot the Mac and hold Option (⌥) to select the Debian Live Installer.
4. Install with defaults.

Once Linux is installed, you want it to stop sleeping even when the display lid is closed. Set the following in /etc/systemd/logind.conf:

[Login]
HandleLidSwitch=ignore
HandleLidSwitchExternalPower=ignore
HandleLidSwitchDocked=ignore

Installing Debian is generic, disabling lid sleep was pretty straight forward. Next step on my journey: how to sign-in into my Claude and OpenAI subscriptions via a browser on a remote machine?

About tokens and window managers#

My plan was to keep using my Claude 5x and ChatGPT Plus subscriptions on Ferris. Raw API tokens add up fast; the subscriptions cap that cost at a flat monthly rate. To use either of them on Ferris, I needed a way to log in via a browser. That ruled out a headless setup and pushed me toward XFCE, a lightweight window manager for Linux. The Debian Live XFCE image ships with Firefox already installed, which covers everything I need.

Getting Windows App by Microsoft on my main Mac to talk to Ferris took some XRDP configuration work. Windows App is Microsoft’s RDP client; on macOS it replaced the older Microsoft Remote Desktop app and connects to any RDP server, which is why it pairs with XRDP on the Linux side. I summarized my learnings in the TIL Configure XRDP and XFCE on Debian 13.

What Ferris actually does for me#

Three jobs keep Ferris on the shelf and on the network: agent runs in YOLO mode, remote control from anywhere, and conversations with my second brain from a phone.

Building software in YOLO mode#

My primary use case for Ferris is building software with Claude in YOLO mode. YOLO mode (Claude Code’s --dangerously-skip-permissions flag) means the coding agent does not stop and ask for permission before running tools. This is the unlock: I prompt Ferris with a set of instructions and the tasks are usually done by the time I check back.

The flag turns off the per-tool permission prompts so the agent can run unattended:

> claude --dangerously-skip-permissions
> # Or as alias
> alias claude-yolo='claude --dangerously-skip-permissions'

My routine workflow is spec-driven development with speq-skill; I have a series on the topic here on the blog. YOLO mode took this to the next level. With permission prompts off, Ferris can work through an entire plan while I am away from the computer.

Remote-controlling sessions#

Anthropic’s Remote Control feature lets you continue any Claude Code session from the web interface, the Claude app on your phone, or the desktop app. The docs are at Continue local sessions from any device.

I run /remote-control some-name inside Claude Code to enable remote access. The next puzzle piece was keeping the terminal session alive that Claude Code was invoked in. tmux solves that (see also my TIL tmux: terminal multiplexer):

# SSH into Ferris
> ssh marco@ferris.local

# Start a new tmux session
marco@ferris> tmux new

# Start Claude in YOLO mode
tmux[0]> claude-yolo

# Trigger Remote Control within the session
claude> /remote-control my-session

Chatting with my second brain on the phone#

For coding I prefer an actual keyboard and a bigger screen. But there is one use case where the phone wins: chatting with my second brain from anywhere.

I took Karpathy’s LLM Wiki gist and built myself an LLM wiki I call second brain. It is a collection of Markdown files about my content and posts, both for this blog and for LinkedIn. Every time I have a question, a thought, or an idea for an article or a post, I use my phone and Claude to iterate on it via a remote session running on Ferris.

Remote Control is the feature I went looking for. Chatting with my second brain from a phone is the one I kept.