desk-switch

Flip a DDC-capable external monitor between two or more Macs sharing it. Type dw in Raycast and the monitor switches.

dw                       # toggle (with 2 devices) or list (with 3+)
dw <device>              # explicit switch (e.g. dw mac-mini)
dw init                  # interactive setup on the first Mac
dw add <name> <input>    # add a new device to the config
dw remove <name>         # drop a device
dw use <name>            # change which device THIS Mac is
dw share                 # generate one-paste install commands for other Macs
dw setup raycast         # register per-device commands in Raycast
dw reset                 # wipe config + generated bindings (start fresh)
dw status                # show config
dw list                  # list displays + show config

The repo is named desk-switch. The binary you run is dw.

How it works

Every modern external monitor exposes a side-channel called DDC/CI over the video cable. The OS can use it to change brightness, volume, and the input source without touching the monitor's physical buttons. dw wraps m1ddc — a small CLI that speaks DDC/CI on Apple Silicon — to write the input source VCP code.

You configure all your devices once on a "main" Mac, then dw share prints a one-paste install command for each other Mac. Each device knows its own identity (this_device) and the full map of devices and their input codes, so any dw <name> call switches the monitor instantly.

Requirements

• Apple Silicon Mac (M1 / M2 / M3 / M4) on macOS 12+
• A DDC-capable external monitor (most modern monitors are; built-in HDMI on entry-level M1 / base M2 Macs is not DDC-capable — use USB‑C or Thunderbolt instead)
• Homebrew
• Raycast (for the hotkey UI)

Install on the main Mac

curl -fsSL https://raw.githubusercontent.com/thrcrt/desk-switch/main/install.sh | bash
dw init

That's it. The installer is idempotent and:

• verifies Apple Silicon macOS,
• installs m1ddc and jq via Homebrew (skipped if already present),
• clones the repo to ~/.local/share/dw (override with DW_INSTALL_DIR),
• symlinks dw onto your PATH, preferring /opt/homebrew/bin.

After install, dw is callable from anywhere — no need to be in any specific directory. If you prefer to clone the repo manually somewhere, that still works: just run ./install.sh from inside the checkout.

dw init walks you through:

1. Which display number to control (usually 1)
2. How many devices share this monitor
3. Each device's name + VCP input code
4. Which device THIS Mac is

Standard VCP codes:

Code	Input
15	DisplayPort 1
16	DisplayPort 2
17	HDMI 1
18	HDMI 2
27	USB‑C

Config goes to ~/.config/dw/config.json.

Install on the other Macs

On the main Mac (after dw init):

$ dw share
## On 'macmini':

  bash <(curl -fsSL https://raw.githubusercontent.com/.../bootstrap.sh) \
    --this macmini --devices "macbook=27,macmini=17,work=15"

Paste the matching command on each other Mac. bootstrap.sh clones the repo, runs install.sh, writes the config, and (if Raycast is installed) generates the per-device Raycast script commands. After it finishes, that Mac is ready — no init wizard.

Raycast integration

dw setup raycast generates one Raycast script command per device into ~/Documents/dw/raycast/. Each script gets a dw → <Device> title and a 🖥 icon. Nothing is uploaded; nothing leaves your Mac.

One-time setup — Raycast has no API for adding a Script Directory, so this single click is unavoidable:

1. Run dw setup raycast — opens Raycast.
2. Raycast Settings (⌘,) → Extensions → Script Commands → + → Add Script Directory.
3. In the file picker, navigate to Documents → dw → raycast and click Open.

After this one-time step, every dw add, dw remove, or dw setup raycast regenerates the scripts in place and Raycast picks them up automatically — no more clicking, ever.

In Raycast: type dw and autocomplete lists every device.

Resetting / starting over

dw reset           # interactive: shows what'll be removed, asks to confirm
dw reset --yes     # skip confirmation

dw reset removes:

• ~/.config/dw/ (the device config)
• ~/Documents/dw/raycast/ (generated Raycast script commands)

It does not touch:

• the dw binary or its symlink — use ./uninstall.sh for that
• Homebrew deps (m1ddc, jq)
• the Raycast "Add Script Directory" entry inside Raycast Settings (the directory will just be empty until you re-run dw setup raycast)

After a reset, run dw init to set up fresh — or, on a secondary Mac, paste the matching dw share line from your main Mac.

Troubleshooting

• m1ddc could not write input — Wrong display selector, or the monitor doesn't support DDC input switching. Run dw list to see what m1ddc detects, and confirm with m1ddc display 1 get luminance that DDC reads work for that display.
• Switches to the wrong input — Re-run dw init (or use dw remove <name> + dw add <name> <new-code>).
• Monitor goes dark with no signal — You wrote a code for an unused input. Recover with the monitor's joystick, then fix the config.

License

MIT — see LICENSE.