Per-monitor wallpaper

[stefanomainardi]

🤖 Written by an AI agent on behalf of @stefanomainardi.

Every monitor shows the same wallpaper, which looks bad when the monitors don't match. My case is a portrait monitor next to a wide one: the shared landscape wallpaper gets upscaled and cropped to fill the tall side, so it's grainy while the wide monitor looks fine.

I'd like a monitor to be able to use its own wallpaper, with the shared one staying the default.

I put together a working version to see if the direction is welcome. Here is the diff against quattro (one commit, four files): quattro...stefanomainardi:omarchy:background-per-monitor

How it works:

• An optional ~/.local/state/omarchy/current/backgrounds.json maps an output name to an image, e.g. { "DP-4": "/path/portrait.jpg" }. No file means today's behavior on every screen.
• The background plugin draws the override on top of the shared one, so the shared fade keeps running underneath and clearing an override never leaves a stale or black frame.
• omarchy-theme-bg-set gets --monitor <output> and --all. A plain set still leaves overrides alone, so a theme switch keeps them.
• The picker (omarchy-theme-bg-switch) asks "this monitor or all?" when you have more than one screen, and sets it accordingly. Single monitor is unchanged.

Verified live on a two-monitor setup with one rotated to portrait: per-monitor overrides, both monitors overridden at once, theme-switch safety, and malformed-file fallback, with no crashes.

A few things I'm unsure about:

• Should the picker default to the focused monitor, or to all monitors?
• Overrides key on the output name (DP-4), which can change on reconnect. The monitor description would be more stable but uglier as a key.
• State file next to current/background, or put the map in shell.json?

Happy to open a PR if you want it.