feat: add sleep/wake resilience, wallpaper shuffle controls, and stability fixes

[ziyadhussain23]

Summary

This PR introduces sleep/wake resilience, wallpaper shuffle & playback controls, DING extension compatibility, and several stability fixes to prevent crashes and UI freezes.

9 files changed — 482 insertions, 70 deletions.

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Changes

1. Sleep/Wake Resilience (extension.js)

Problem: After system suspend/resume, the GStreamer renderer pipeline becomes stale, causing the entire GNOME Shell UI to freeze for 10–30 seconds on wake.

Solution:

• Subscribe to org.freedesktop.login1.Manager → PrepareForSleep D-Bus signal.
• Before sleep: SIGKILL the renderer process immediately to tear down the stale GStreamer pipeline cleanly.
• After wake: Relaunch the renderer, wait 5 seconds for it to initialize, then issue a setPlay() D-Bus call to resume playback.
• Add an _isSuspending flag to prevent autoPause from accidentally re-launching the renderer during the suspend window.
• Suppress the playbackState mismatch handler during startup and wake recovery to prevent the renderer from being force-paused before it is ready.

2. Wallpaper Shuffle & Playback Controls (renderer.js, dbus.js, panelMenu.js)

• nextWallpaper / previousWallpaper D-Bus methods — enable cycling through wallpapers from external scripts, D-Bus calls, or the panel menu.
• Shuffle history tracking in the renderer, so previousWallpaper navigates back through recently played files (up to 50 entries).
• Smooth fade transition between wallpapers using Clutter opacity animation, with a user-configurable fade-duration GSettings key (default: 500 ms).
• Panel menu enhancements — added a "Previous Wallpaper" button and a label displaying the current wallpaper filename.

3. DING Extension Compatibility (gnomeShellOverride.js)

Problem: When the DING desktop icons extension (ding@rastersoft.com) is enabled alongside Hanabi, disabling/enabling Hanabi throws replaceData.old_get_window_actors is undefined because both extensions override global.get_window_actors.

Solution:

• Detect if DING is enabled and skip the get_window_actors override to avoid the conflict.
• Wrap _updateBackgrounds, _updateWorkspacesViews, and blur-my-shell hooks in _reloadBackgrounds() with try-catch for defensive error handling.

4. Disposed Actor Safety (wallpaper.js)

Problem: Race conditions during extension disable or monitor hotplug can cause operations on already-destroyed LiveWallpaper Clutter actors, leading to crashes.

Solution:

• Add an _isDestroyed flag set on the destroy signal.
• Guard _applyWallpaper callback and other async operations against destroyed actors.
• Cancel pending timeouts on destroy to prevent use-after-free.
• Wrap get_window_actors(false) in _getRenderer() with try-catch.

5. PlaybackState Mismatch Suppression (playbackState.js)

• Add a suppressMismatch boolean flag that the extension sets during startup (first 5 seconds) and wake recovery to temporarily bypass the isPlayingChanged force-pause logic.
• This prevents a race where the mismatch handler detects the renderer as "playing" before autoPause has fully initialized, causing an unwanted immediate pause.

6. Preferences & Schema (prefs.js, gschema.xml)

• Add fade-duration key to GSettings schema (integer, default 500 ms, range 0–5000).
• Add "Fade Transition Duration" SpinButton to the Wallpaper section of preferences.

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Files Changed

File	Change
src/extension.js	Sleep/wake handler, delayed autoPause, suppressMismatch, SIGKILL renderer
src/renderer/renderer.js	Fade transition, shuffle history, next/previous wallpaper methods
src/gnomeShellOverride.js	DING compatibility guard, try-catch wrappers
src/panelMenu.js	Previous Wallpaper button, wallpaper filename display
src/dbus.js	nextWallpaper / previousWallpaper D-Bus wrappers
src/playbackState.js	suppressMismatch flag
src/wallpaper.js	_isDestroyed guard, timeout cleanup, try-catch
src/prefs.js	Fade duration SpinButton
src/schemas/...gschema.xml	fade-duration key

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Testing

• Tested on GNOME 47 (Fedora 41 / GJS 1.82).
• Verified sleep/wake cycle: no UI freeze, video resumes playback automatically.
• Verified wallpaper shuffle: next/previous cycling works from panel menu and D-Bus.
• Verified DING extension compatibility: no errors on enable/disable with DING active.
• Verified extension disable/enable cycle: no disposed actor crashes.