feat: expose player over MPRIS for system media controls

Register a session D-Bus MPRIS service (org.mpris.MediaPlayer2.mtsmusic)
in both the TUI and Qt apps, so the player shows up as a media source:
play/pause, next/previous, seek, metadata (title/artist/album/length/art)
and volume can be controlled from the GNOME media-controls extension,
playerctl and other MPRIS clients. Integration is optional and degrades
to a no-op without dbus-next or a session bus.

qt_app.py

@@ -90,6 +90,7 @@ from settings import (
     load_settings,
     update_settings,
 )
+from mpris import MprisService, track_object_path
 
 APP_QSS = """
 QWidget {
@@ -439,6 +440,55 @@ class Scrim(QFrame):
         super().mousePressEvent(event)
 
 
+class MprisBridge(QObject):
+    """Принимает команды MPRIS из D-Bus и перекладывает их в поток Qt."""
+
+    play = Signal()
+    pause = Signal()
+    playPause = Signal()
+    stop = Signal()
+    next = Signal()
+    previous = Signal()
+    seek = Signal(int)
+    setPosition = Signal(str, int)
+    volume = Signal(float)
+    raiseWindow = Signal()
+    quitApp = Signal()
+
+    def on_play(self) -> None:
+        self.play.emit()
+
+    def on_pause(self) -> None:
+        self.pause.emit()
+
+    def on_play_pause(self) -> None:
+        self.playPause.emit()
+
+    def on_stop(self) -> None:
+        self.stop.emit()
+
+    def on_next(self) -> None:
+        self.next.emit()
+
+    def on_previous(self) -> None:
+        self.previous.emit()
+
+    def on_seek(self, offset: int) -> None:
+        self.seek.emit(int(offset))
+
+    def on_set_position(self, track_id: str, position: int) -> None:
+        self.setPosition.emit(str(track_id), int(position))
+
+    def on_volume(self, value: float) -> None:
+        self.volume.emit(float(value))
+
+    def on_raise(self) -> None:
+        self.raiseWindow.emit()
+
+    def on_quit(self) -> None:
+        self.quitApp.emit()
+
+
 class QtMusicApp(QMainWindow):
     def __init__(self, api: Api) -> None:
         super().__init__()
@@ -489,6 +539,22 @@ class QtMusicApp(QMainWindow):
         self._update_cover_size()
         self.play_btn.setFocus()
 
+        # MPRIS: система видит плеер как источник звука (панель GNOME, playerctl).
+        self.mpris_bridge = MprisBridge(self)
+        self.mpris_bridge.play.connect(self.mpris_play)
+        self.mpris_bridge.pause.connect(self.mpris_pause)
+        self.mpris_bridge.playPause.connect(self.toggle_play)
+        self.mpris_bridge.stop.connect(self.mpris_stop)
+        self.mpris_bridge.next.connect(lambda: self.advance(1))
+        self.mpris_bridge.previous.connect(lambda: self.advance(-1))
+        self.mpris_bridge.seek.connect(self.mpris_seek)
+        self.mpris_bridge.setPosition.connect(self.mpris_set_position)
+        self.mpris_bridge.volume.connect(self.mpris_set_volume)
+        self.mpris_bridge.raiseWindow.connect(self.mpris_raise)
+        self.mpris_bridge.quitApp.connect(self.close)
+        self.mpris = MprisService(self.mpris_bridge, identity="MTS Music")
+        self.mpris.update_volume(self.audio.volume())
+
         QTimer.singleShot(0, self.load_initial)
 
     # -- построение интерфейса -------------------------------------------
@@ -892,6 +958,8 @@ class QtMusicApp(QMainWindow):
         self.volume_value.setText(f"{value} %")
         self.audio.setVolume(value / 100)
         self.update_setting("volume", value)
+        if getattr(self, "mpris", None):
+            self.mpris.update_volume(value / 100)
 
     def on_device_changed(self, index: int) -> None:
         device = self.device_combo.itemData(index)
@@ -1142,6 +1210,7 @@ class QtMusicApp(QMainWindow):
         self.duration_label.setText(fmt_millis(duration))
         self.update_like_button()
         self.update_play_button()
+        self._update_mpris_metadata()
 
     def update_like_button(self, liked: bool | None = None) -> None:
         if liked is None:
@@ -1154,6 +1223,7 @@ class QtMusicApp(QMainWindow):
     def update_play_button(self, *args) -> None:
         playing = self.player.playbackState() == QMediaPlayer.PlaybackState.PlayingState
         self.play_btn.setIcon(media_icon("pause" if playing else "play", 80))
+        self._update_mpris_status()
 
     # -- обложка ----------------------------------------------------------
 
@@ -1266,6 +1336,8 @@ class QtMusicApp(QMainWindow):
         if duration > 1:
             self.slider.setValue(min(position, duration))
         self.elapsed_label.setText(fmt_millis(position))
+        if getattr(self, "mpris", None):
+            self.mpris.update_position(int(position) * 1000)
 
     def on_player_duration(self, duration: int) -> None:
         track_duration = int((self.current or {}).get("durationMs") or 0)
@@ -1286,6 +1358,8 @@ class QtMusicApp(QMainWindow):
         self._seeking = False
         self.player.setPosition(value)
         self.elapsed_label.setText(fmt_millis(value))
+        if getattr(self, "mpris", None):
+            self.mpris.notify_seeked(value * 1000)
 
     def on_slider_action(self, action: int) -> None:
         # Колесо и стрелки, когда слайдер в фокусе (клик обрабатывает ClickSlider).
@@ -1293,6 +1367,8 @@ class QtMusicApp(QMainWindow):
             value = self.slider.value()
             self.player.setPosition(value)
             self.elapsed_label.setText(fmt_millis(value))
+            if getattr(self, "mpris", None):
+                self.mpris.notify_seeked(value * 1000)
 
     def seek(self, delta_ms: int) -> None:
         if self.player.source().isEmpty():
@@ -1302,6 +1378,92 @@ class QtMusicApp(QMainWindow):
         self.player.setPosition(position)
         self.slider.setValue(position)
         self.elapsed_label.setText(fmt_millis(position))
+        if getattr(self, "mpris", None):
+            self.mpris.notify_seeked(position * 1000)
+
+    # -- MPRIS ------------------------------------------------------------
+
+    def mpris_play(self) -> None:
+        if self.player.playbackState() != QMediaPlayer.PlaybackState.PlayingState:
+            self.toggle_play()
+
+    def mpris_pause(self) -> None:
+        if self.player.playbackState() == QMediaPlayer.PlaybackState.PlayingState:
+            self.toggle_play()
+
+    def mpris_stop(self) -> None:
+        self.player.stop()
+        self.slider.setValue(0)
+        self.elapsed_label.setText("0:00")
+        self.update_play_button()
+
+    def mpris_seek(self, offset_us: int) -> None:
+        if self.player.source().isEmpty():
+            return
+        duration = self.slider.maximum()
+        position = max(
+            0, min(self.player.position() + offset_us // 1000, max(0, duration - 500))
+        )
+        self.player.setPosition(position)
+        self.slider.setValue(position)
+        self.elapsed_label.setText(fmt_millis(position))
+        self.mpris.notify_seeked(position * 1000)
+
+    def mpris_set_position(self, track_path: str, position_us: int) -> None:
+        if not self.current:
+            return
+        if track_object_path(self.current.get("id")) != track_path:
+            return
+        position = max(0, position_us // 1000)
+        self.player.setPosition(position)
+        self.slider.setValue(position)
+        self.elapsed_label.setText(fmt_millis(position))
+        self.mpris.update_position(position_us)
+
+    def mpris_set_volume(self, value: float) -> None:
+        value = max(0.0, min(1.0, value))
+        self.audio.setVolume(value)
+        self.volume_slider.setValue(int(round(value * 100)))
+
+    def mpris_raise(self) -> None:
+        self.showNormal()
+        self.raise_()
+        self.activateWindow()
+
+    def _update_mpris_status(self) -> None:
+        if not getattr(self, "mpris", None):
+            return
+        state = self.player.playbackState()
+        if state == QMediaPlayer.PlaybackState.PlayingState:
+            status = "Playing"
+        elif state == QMediaPlayer.PlaybackState.PausedState:
+            status = "Paused"
+        else:
+            status = "Stopped"
+        self.mpris.update_playback_status(status)
+
+    def _update_mpris_metadata(self) -> None:
+        if not getattr(self, "mpris", None):
+            return
+        track = self.current
+        if not track:
+            self.mpris.clear_metadata()
+            self.mpris.update_capabilities(
+                can_next=False, can_previous=False, can_seek=False
+            )
+            return
+        self.mpris.update_metadata(
+            track.get("id"),
+            title=str(track.get("title") or ""),
+            artist=track_artist(track),
+            album=track_album(track),
+            duration_ms=int(track.get("durationMs") or 0),
+            art_url=track_cover_url(track) or "",
+        )
+        has_queue = bool(self.queue or self.wave)
+        self.mpris.update_capabilities(
+            can_next=has_queue, can_previous=has_queue, can_seek=True
+        )
 
     def advance(self, direction: int) -> None:
         queue = self.queue or self.wave
@@ -1629,6 +1791,8 @@ class QtMusicApp(QMainWindow):
 
     def closeEvent(self, event) -> None:  # noqa: N802
         self.player.stop()
+        if getattr(self, "mpris", None):
+            self.mpris.close()
         self.pool.clear()
         super().closeEvent(event)