feat: refresh views on all playlist mutations

- Add EV_PLAYLIST_TRACK_ADDED (22) — emitted when a track is
  successfully added to a playlist
- If the currently-open playlist is the one modified, re-fetch it
  so the track appears in the list immediately
- After creating a playlist, open it automatically so the user
  lands in the new (empty) playlist view right away
- Sidebar already refreshes on create/delete; this ensures the
  track list view also stays in sync

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

rust/include/qobuz_backend.h

@@ -33,6 +33,7 @@ enum QobuzEvent {
     EV_GENERIC_ERR      = 19,
     EV_PLAYLIST_CREATED      = 20,
     EV_PLAYLIST_DELETED      = 21,
+    EV_PLAYLIST_TRACK_ADDED  = 22,
 };
 
 // Callback signature

rust/src/lib.rs

@@ -562,6 +562,7 @@ pub unsafe extern "C" fn qobuz_backend_remove_fav_album(ptr: *mut Backend, album
 
 pub const EV_PLAYLIST_CREATED: c_int = 20;
 pub const EV_PLAYLIST_DELETED: c_int = 21;
+pub const EV_PLAYLIST_TRACK_ADDED: c_int = 22;
 
 #[no_mangle]
 pub unsafe extern "C" fn qobuz_backend_create_playlist(ptr: *mut Backend, name: *const c_char) {
@@ -601,8 +602,10 @@ pub unsafe extern "C" fn qobuz_backend_add_track_to_playlist(
     let client = inner.client.clone();
     let cb = inner.cb; let ud = inner.ud;
     spawn(inner, async move {
-        if let Err(e) = client.lock().await.add_track_to_playlist(playlist_id, track_id).await {
-            call_cb(cb, ud, EV_GENERIC_ERR, &err_json(&e.to_string()));
+        match client.lock().await.add_track_to_playlist(playlist_id, track_id).await {
+            Ok(()) => call_cb(cb, ud, EV_PLAYLIST_TRACK_ADDED,
+                &serde_json::json!({"playlist_id": playlist_id}).to_string()),
+            Err(e) => call_cb(cb, ud, EV_GENERIC_ERR, &err_json(&e.to_string())),
         }
     });
 }

src/backend/qobuzbackend.cpp

@@ -241,6 +241,9 @@ void QobuzBackend::onEvent(int eventType, const QString &json)
     case 21: // EV_PLAYLIST_DELETED
         emit playlistDeleted(obj);
         break;
+    case 22: // EV_PLAYLIST_TRACK_ADDED
+        emit playlistTrackAdded(static_cast<qint64>(obj["playlist_id"].toDouble()));
+        break;
     case EV_GENERIC_ERR:
     case EV_TRACK_URL_ERR:
         emit error(obj["error"].toString());

src/backend/qobuzbackend.hpp

@@ -78,6 +78,7 @@ signals:
     void playlistLoaded(const QJsonObject &playlist);
     void playlistCreated(const QJsonObject &playlist);
     void playlistDeleted(const QJsonObject &result);
+    void playlistTrackAdded(qint64 playlistId);
 
     // favorites
     void favTracksLoaded(const QJsonObject &result);

src/list/tracks.hpp

@@ -30,6 +30,7 @@ namespace List
 
         /// Set which playlist is currently displayed (0 = none).
         void setPlaylistContext(qint64 playlistId);
+        qint64 playlistId() const { return m_playlistId; }
         /// Provide the user's playlist list for the "Add to playlist" submenu.
         void setUserPlaylists(const QVector<QPair<qint64, QString>> &playlists);
 

src/mainwindow.cpp

@@ -80,7 +80,13 @@ MainWindow::MainWindow(QobuzBackend *backend, QWidget *parent)
     connect(m_backend, &QobuzBackend::playlistLoaded,   this, &MainWindow::onPlaylistLoaded);
     connect(m_backend, &QobuzBackend::playlistCreated,   this, &MainWindow::onPlaylistCreated);
     connect(m_backend, &QobuzBackend::playlistDeleted,   this, [this](const QJsonObject &) {
-        statusBar()->showMessage(tr("Playlist deleted"), 3000);
+        // status bar message is also shown by library's openPlaylistDeleted handler
+    });
+    connect(m_backend, &QobuzBackend::playlistTrackAdded, this, [this](qint64 playlistId) {
+        // Refresh the currently shown playlist if a track was added to it
+        if (m_content->tracksList()->playlistId() == playlistId)
+            m_backend->getPlaylist(playlistId);
+        statusBar()->showMessage(tr("Track added to playlist"), 3000);
     });
     connect(m_backend, &QobuzBackend::trackChanged,   this, &MainWindow::onTrackChanged);
     connect(m_backend, &QobuzBackend::error, this, [this](const QString &msg) {
@@ -337,8 +343,12 @@ void MainWindow::onSearchToggled(bool visible)
 
 void MainWindow::onPlaylistCreated(const QJsonObject &playlist)
 {
-    statusBar()->showMessage(
-        tr("Playlist '%1' created").arg(playlist["name"].toString()), 4000);
+    const QString name = playlist["name"].toString();
+    statusBar()->showMessage(tr("Playlist '%1' created").arg(name), 4000);
+    // Open the new playlist immediately
+    const qint64 id = static_cast<qint64>(playlist["id"].toDouble());
+    if (id > 0)
+        m_backend->getPlaylist(id);
 }
 
 void MainWindow::onUserPlaylistsChanged(const QVector<QPair<qint64, QString>> &playlists)