Add a tile mode to the bundled YouTube web app

[Vegasq]

The problem

Omarchy ships YouTube as a web app — Super + Shift + Y in default/hypr/bindings/applications.lua, an applications/YouTube.desktop, and dedicated window rules in default/hypr/apps/browser.lua. It launches as chromium --app=https://youtube.com/, so it is an ordinary window in the tiling layout.

But YouTube only knows two sizes: embedded in the page, or fullscreen. Fullscreen goes through the Fullscreen API, which makes Hyprland promote the window to cover the whole monitor — it leaves the tile entirely. There is no way to say "just fill this tile with the video", which is the thing you actually want in a tiling session.

The change

screenrecording-2026-08-30_17-31-45_trimmed.mp4

A fourth bundled Chromium extension, next to WhatsApp Slim — which exists for the same reason. Omarchy ships the web app, so Omarchy fixes the web app.

Tile mode lifts #movie_player out of the page as a viewport-sized fixed element: the video fills the window edge to edge while the window stays exactly where the tiling layout put it. No Fullscreen API, no layout change.

Key	Action
f	Toggle tile mode
Shift + F	Real fullscreen, unchanged
z	Zoom to fill — crop to the tile instead of letterboxing
Esc	Leave tile mode
Alt + S	Settings

z earns its place: a tile is rarely 16:9, so a letterboxed video leaves black bars down two sides.

Two implementation notes worth flagging for review:

• Hiding is structural, not enumerated. It walks up from the player and hides each ancestor's siblings, so masthead, live chat, the theater-mode metadata row, engagement panels and endscreens are all covered without naming any of them. Enumerating surfaces in CSS meant a new bug for every page variant, and it rots whenever YouTube renames a container.
• Settings live behind Alt + S because an --app window has no toolbar, and therefore no extension popup.

Scope: deliberately layout only

The extension this is extracted from also repaints YouTube with the active Omarchy palette. That half is left out on purpose, for two reasons:

1. It works by overriding YouTube's internal --yt-spec-* design tokens, which is exactly the surface that moves under a redesign. Tile mode is CSS positioning and key handling, which is far more durable — and a bundled extension is a maintenance commitment.
2. It cannot work from a bundled copy anyway. The palette is generated into the extension directory by a theme-set hook, and $OMARCHY_PATH is root-owned and pacman-managed, so a user-run hook has nowhere to write and an upgrade would clobber it regardless. Doing it properly needs a native messaging host, like copy-url and yt-dlp have. That is a reasonable follow-up, but it does not belong in the same change as the layout fix.

So there are no --omy-* variables anywhere in this extension, and a test asserts that stays true.

Details

• manifest.json pins a key, matching all three existing bundled extensions, so the id does not drift with the load path.
• migrations/1788118063.sh adds the extension to existing browser flag files — config/chromium-flags.conf does not reach users who already have a copy in ~/.config. It follows migrations/1785543725.sh, which did the same for WhatsApp Slim.
• Only permission is storage, for the settings.

Verification

./test/cli passes. ./test/shell passes; the six failures on my machine (bar-icon-geometry, config, snapper, theme-install-guards, unowned-system-paths, windows-vm-mount-boundary) fail identically on a clean checkout — they are environment checks against an unlinked tree.

New test/shell.d/chromium-youtube-tile-test.sh covers the derived extension id, that the flags file loads it, that a migration exists, that no palette variables crept in, and that the content script parses.

Verified in a real --app window on a ThinkPad X280 running Omarchy 4.0.1, against a live YouTube page:

• Tile mode engages automatically; hyprctl reports the window still at its tiled geometry with fullscreen: 0, and the video fills it edge to edge.
• Alt + S renders the settings overlay over the tiled player.
• z crops a 4:3 video to fill a 941×509 tile instead of letterboxing it.
• No content-script errors in the Chromium log.

Provenance

Extracted from omarchy-youtube, which I wrote; MIT, and mine to relicense into this tree. It is also on the Chrome Web Store, but a bundled copy is better for a shipped web app — no install step, no store account, and it tracks the repo.

Happy to cut anything here that reads as too much for a default, including the settings overlay — tile mode itself is the part that matters.