Let OWE own video backgrounds while it runs

The background plugin now watches for the OWE daemon socket. While OWE is
running, the desktop yields video playback to it and the shell keeps
stills. The lock screen keeps its own playback.

This lets Omarchy cooperate with OWE without OWE editing shell.json, so
the engine can ship as a package.

Add a package-list note that owe-wallpaper-engine must be added once it is
packaged.

install/omarchy-base.packages

@@ -107,6 +107,8 @@ python-poetry-core
 ttfx
 qemu-user-static-binfmt
 qrencode
+# TODO: add owe-wallpaper-engine here once it is packaged. The shell yields
+# video backgrounds to it while its daemon runs.
 qt6-imageformats
 qt6-multimedia
 qt6-multimedia-ffmpeg

manual/39-backgrounds.md

@@ -4,6 +4,6 @@ Every theme ships with its own set of backgrounds, and you can add extras of you
 
 You can do this most easily by going to _Install > Style > Background_ in the Omarchy Menu. That'll bring up the folder where the backgrounds for that theme is stored. Hit `Super + Shift + F` to start another file manager, find your background, copy it over.  Now it'll be included in the choices of backgrounds you can select between using `Super + Ctrl + Space`.
 
-Backgrounds can be videos as well as stills. Drop an `mp4`, `m4v`, `mov`, `webm`, `mkv`, or `avi` file in the same folder and it appears alongside the images, playing on a loop. Only your first monitor's wallpaper plays a video's sound track, through the default audio output at the system volume, and the lock screen stays silent. Playback stops on its own whenever nothing can see it — while a fullscreen window covers that monitor, while the screensaver is up, and once a locked screen has gone dark — but a video wallpaper still costs far more power than a still one, and each monitor decodes its own copy.
+Backgrounds can be videos as well as stills. Drop an `mp4`, `m4v`, `mov`, `webm`, `mkv`, or `avi` file in the same folder and it appears alongside the images, playing on a loop. Only your first monitor's wallpaper plays a video's sound track, through the default audio output at the system volume, and the lock screen stays silent. Playback stops on its own whenever nothing can see it — while a fullscreen window covers that monitor, while the screensaver is up, and once a locked screen has gone dark — but a video wallpaper still costs far more power than a still one, and each monitor decodes its own copy. When the OWE wallpaper engine is running, it takes over video backgrounds and the shell keeps only stills.
 
 You can find a huge collection of cool curated backgrounds on https://github.com/dharmx/walls.

shell/Ui/BackgroundMedia.qml

@@ -8,6 +8,10 @@ Item {
   property int version: 0
   property bool playbackEnabled: true
   property bool audioEnabled: false
+  // The desktop yields video playback to OWE while it runs, so two engines
+  // never decode the same file. The lock screen leaves this off and keeps its
+  // own playback.
+  property bool deferVideo: false
   // Bumped when the file behind an unchanged path may have been replaced.
   // Images cache-bust through version; a video is rebuilt, since FFmpeg
   // would read a query as part of the filename.
@@ -37,7 +41,7 @@ Item {
   Loader {
     id: videoLoader
     anchors.fill: parent
-    active: root.path !== "" && root.video && !root.reloading
+    active: root.path !== "" && root.video && !root.reloading && !root.deferVideo
     source: "BackgroundVideo.qml"
   }
 

shell/plugins/background/Background.qml

@@ -32,6 +32,25 @@ Item {
   // services so playback can stop whenever nothing can see the wallpaper.
   property var shell: null
 
+  // When the OWE wallpaper engine is running, it owns video backgrounds. This
+  // plugin keeps stills, which OWE hands back to it, and the lock screen keeps
+  // its own playback.
+  property bool oweActive: false
+
+  Process {
+    id: oweStatusProc
+    command: ["bash", "-c", "test -S \"${XDG_RUNTIME_DIR:-/run/user/$(id -u)}/owe/owed.sock\""]
+    onExited: root.oweActive = (exitCode === 0)
+  }
+
+  Timer {
+    id: oweStatusTimer
+    interval: 5000
+    repeat: true
+    running: true
+    onTriggered: if (!oweStatusProc.running) oweStatusProc.running = true
+  }
+
   // Stop a video wallpaper's decoding whenever it is covered. Qt's FFmpeg
   // engine drives its own clock, so an unseen player keeps decoding until it
   // is told not to — a locked laptop would otherwise decode until it died.
@@ -204,7 +223,10 @@ Item {
     }
   }
 
-  Component.onCompleted: refreshBackground()
+  Component.onCompleted: {
+    oweStatusProc.running = true
+    refreshBackground()
+  }
 
   Variants {
     model: Quickshell.screens
@@ -264,6 +286,7 @@ Item {
         anchors.fill: parent
         path: root.displayedBackground
         reloads: root.displayedReloads
+        deferVideo: root.oweActive
         playbackEnabled: !root.sessionObscured && !root.powerSaverActive && !panel.fullscreenHere
         audioEnabled: panel.firstScreen
         onReadyChanged: {

test/shell.d/video-background-test.sh

@@ -87,6 +87,15 @@ assert(
   'video switches bypass the image-only reveal stack and use the durable background path'
 )
 assert(backgroundQml.includes('BackgroundMedia {') && lockQml.includes('BackgroundMedia {'), 'desktop and lock screen share video-capable media rendering')
+assert(
+  backgroundQml.includes('property bool oweActive: false') &&
+    backgroundQml.includes('/owe/owed.sock') &&
+    /deferVideo: root\.oweActive/.test(backgroundQml) &&
+    /property bool deferVideo: false/.test(mediaQml) &&
+    /active: root\.path !== "" && root\.video && !root\.reloading && !root\.deferVideo/.test(mediaQml) &&
+    !lockQml.includes('deferVideo'),
+  'the desktop yields video backgrounds to OWE while it is running, and the lock keeps its own playback'
+)
 assert(
   lockQml.includes('source: wallpaper.video ? null : wallpaper') &&
     lockQml.includes('visible: !wallpaper.video') &&