Defer initial playback-rate seek to ASYNC_DONE

An early seek right after set_state(PLAYING) raced the pipeline's
preroll and GStreamer silently dropped it, so a configured custom
rate only took effect after the first EOS loop-restart. Instead,
flag the pending seek and fire it from the first ASYNC_DONE bus
message, once the pipeline is actually ready to seek.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

lib/liveWallpaper.js

@@ -80,6 +80,7 @@ export class LiveWallpaperManager {
         this._busWatchId = 0;
         this._eosSeekTimeoutId = 0;
         this._lastEosSeekTimeMs = 0;
+        this._pendingInitialRateSeek = false;
         this._monitorsChangedId = 0;
         this._fullscreenChangedId = 0;
         this._upowerProxy = null;
@@ -279,11 +280,17 @@ export class LiveWallpaperManager {
             this._applyMute();
             const stateChangeResult = this._playbin.set_state(Gst.State.PLAYING);
             this._logger.debug(`playbin.set_state(PLAYING) returned ${stateChangeResult}`);
-            // set_state(PLAYING) alone always starts at native rate 1.0 —
+            // Seeking here immediately would race the pipeline's preroll —
-            // without this, a configured custom speed only ever took effect
+            // GStreamer can only seek once a state change has actually
-            // once the first EOS loop-restart seek ran.
+            // completed, so an early seek is silently dropped and playback
-            if (this._settings.get_double(SettingsKey.LIVE_WALLPAPER_PLAYBACK_RATE) !== 1.0)
+            // sticks at native 1.0x. Instead, defer to the first ASYNC_DONE
-                this._seekToLoopStart();
+            // bus message (handled in _onBusMessage), which fires once the
+            // pipeline is actually ready to seek.
+            const initialRate = this._settings.get_double(SettingsKey.LIVE_WALLPAPER_PLAYBACK_RATE);
+            this._pendingInitialRateSeek = initialRate !== 1.0;
+            this._logger.debug(
+                `Live wallpaper: configured playback rate ${initialRate}, ` +
+                `deferring initial seek to ASYNC_DONE: ${this._pendingInitialRateSeek}`);
 
             this._frameCount = 0;
             this._pollCount = 0;
@@ -409,6 +416,14 @@ export class LiveWallpaperManager {
         case Gst.MessageType.EOS:
             this._loopPlayback();
             break;
+        case Gst.MessageType.ASYNC_DONE:
+            this._logger.debug(
+                `Live wallpaper: ASYNC_DONE received (pending initial rate seek: ${this._pendingInitialRateSeek})`);
+            if (this._pendingInitialRateSeek) {
+                this._pendingInitialRateSeek = false;
+                this._seekToLoopStart();
+            }
+            break;
         case Gst.MessageType.ERROR: {
             const [error, debug] = message.parse_error();
             this._logger.error(error, `Live wallpaper playback error (${debug ?? 'no debug info'})`);
@@ -466,9 +481,11 @@ export class LiveWallpaperManager {
         this._lastEosSeekTimeMs = GLib.get_monotonic_time() / 1000;
         const Gst = this._Gst;
         const rate = this._settings.get_double(SettingsKey.LIVE_WALLPAPER_PLAYBACK_RATE);
-        this._playbin.seek(
+        const ok = this._playbin.seek(
             rate, Gst.Format.TIME, Gst.SeekFlags.FLUSH | Gst.SeekFlags.KEY_UNIT,
             Gst.SeekType.SET, 0, Gst.SeekType.NONE, -1);
+        this._logger.debug(
+            `Live wallpaper: loop-restart seek to rate ${rate} ${ok ? 'succeeded' : 'FAILED (seek() returned false)'}`);
     }
 
     _stateName(state) {
@@ -488,12 +505,17 @@ export class LiveWallpaperManager {
         const Gst = this._Gst;
         const rate = this._settings.get_double(SettingsKey.LIVE_WALLPAPER_PLAYBACK_RATE);
         const [ok, position] = this._playbin.query_position(Gst.Format.TIME);
-        if (!ok)
+        if (!ok) {
+            this._logger.debug('Live wallpaper: applyPlaybackRate aborted, query_position() failed');
             return;
+        }
 
-        this._playbin.seek(
+        const seekOk = this._playbin.seek(
             rate, Gst.Format.TIME, Gst.SeekFlags.FLUSH | Gst.SeekFlags.ACCURATE,
             Gst.SeekType.SET, position, Gst.SeekType.NONE, -1);
+        this._logger.debug(
+            `Live wallpaper: applyPlaybackRate to ${rate} at position ${position} ` +
+            `${seekOk ? 'succeeded' : 'FAILED (seek() returned false)'}`);
     }
 
     /**