fix: lazy-load genre/playlist views and cap playlist search scrolling

- Defer eager-load scrollbar checks to next event loop iteration via
  QTimer::singleShot(0), fixing initial load not filling the viewport
- Playlist search: eagerly fill viewport, then show "Load more playlists…"
  button instead of infinite scroll to avoid loading thousands of results
- Increase search page size from 8 to 25
- Featured/discover playlists keep auto-scroll behavior unchanged

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

src/view/genrebrowser.cpp

@@ -9,7 +9,9 @@
 #include <QListWidget>
 #include <QMenu>
 #include <QPushButton>
+#include <QScrollBar>
 #include <QSignalBlocker>
+#include <QTimer>
 #include <QTreeWidgetItem>
 #include <QVBoxLayout>
 
@@ -120,8 +122,18 @@ GenreBrowserView::GenreBrowserView(QobuzBackend *backend, PlayQueue *queue, QWid
     m_playlistList->header()->setSectionResizeMode(3, QHeaderView::ResizeToContents);
     m_playlistList->header()->setStretchLastSection(false);
 
+    auto *playlistPage = new QWidget(this);
+    auto *playlistPageLayout = new QVBoxLayout(playlistPage);
+    playlistPageLayout->setContentsMargins(0, 0, 0, 0);
+    playlistPageLayout->setSpacing(0);
+    playlistPageLayout->addWidget(m_playlistList, 1);
+
+    m_loadMorePlaylistsBtn = new QPushButton(tr("Load more playlists…"), this);
+    m_loadMorePlaylistsBtn->hide();
+    playlistPageLayout->addWidget(m_loadMorePlaylistsBtn);
+
     m_resultsStack->addWidget(m_albumList);
-    m_resultsStack->addWidget(m_playlistList);
+    m_resultsStack->addWidget(playlistPage);
     layout->addWidget(m_resultsStack, 1);
 
     connect(m_backend, &QobuzBackend::genresLoaded,
@@ -180,6 +192,12 @@ GenreBrowserView::GenreBrowserView(QobuzBackend *backend, PlayQueue *queue, QWid
             this, &GenreBrowserView::onAlbumScroll);
     connect(m_playlistList->verticalScrollBar(), &QScrollBar::valueChanged,
             this, &GenreBrowserView::onPlaylistScroll);
+    connect(m_loadMorePlaylistsBtn, &QPushButton::clicked, this, [this] {
+        m_loadMorePlaylistsBtn->hide();
+        requestPlaylistsPage(m_lastPlaylistGenreIds, m_lastPlaylistType,
+                             m_lastPlaylistTags, m_lastPlaylistQuery,
+                             m_playlistOffset, true);
+    });
 
     m_kindCombo->setCurrentIndex(0);
     refreshModeUi();
@@ -391,9 +409,12 @@ void GenreBrowserView::onFeaturedAlbumsLoaded(const QJsonObject &result)
     }
 
     // If the viewport is not scrollable yet, eagerly fetch more pages.
+    // Deferred: the scrollbar maximum isn't updated until after layout runs.
+    QTimer::singleShot(0, this, [this] {
         QScrollBar *bar = m_albumList->verticalScrollBar();
         if (bar && bar->maximum() == 0 && m_albumOffset < m_albumTotal)
             requestAlbumsPage(m_lastAlbumGenreIds, m_lastAlbumType, m_albumOffset, true);
+    });
 }
 
 void GenreBrowserView::onFeaturedPlaylistsLoaded(const QJsonObject &result)
@@ -413,9 +434,11 @@ void GenreBrowserView::onFeaturedPlaylistsLoaded(const QJsonObject &result)
         m_playlistTotal = m_playlistOffset;
     m_loadingPlaylists = false;
 
+    QTimer::singleShot(0, this, [this] {
         QScrollBar *bar = m_playlistList->verticalScrollBar();
         if (bar && bar->maximum() == 0 && m_playlistOffset < m_playlistTotal)
             requestPlaylistsPage(m_lastPlaylistGenreIds, m_lastPlaylistType, m_lastPlaylistTags, m_lastPlaylistQuery, m_playlistOffset, true);
+    });
 }
 
 void GenreBrowserView::onDiscoverPlaylistsLoaded(const QJsonObject &result)
@@ -435,9 +458,11 @@ void GenreBrowserView::onDiscoverPlaylistsLoaded(const QJsonObject &result)
         m_playlistTotal = m_playlistOffset;
     m_loadingPlaylists = false;
 
+    QTimer::singleShot(0, this, [this] {
         QScrollBar *bar = m_playlistList->verticalScrollBar();
         if (bar && bar->maximum() == 0 && m_playlistOffset < m_playlistTotal)
             requestPlaylistsPage(m_lastPlaylistGenreIds, m_lastPlaylistType, m_lastPlaylistTags, m_lastPlaylistQuery, m_playlistOffset, true);
+    });
 }
 
 void GenreBrowserView::onPlaylistSearchLoaded(const QJsonObject &result)
@@ -456,9 +481,25 @@ void GenreBrowserView::onPlaylistSearchLoaded(const QJsonObject &result)
         m_playlistTotal = m_playlistOffset;
     m_loadingPlaylists = false;
 
+    // Eagerly fill the viewport, then switch to a manual "Load more" button.
+    if (m_playlistOffset >= m_playlistTotal) {
+        m_loadMorePlaylistsBtn->hide();
+        m_searchViewportFilled = true;
+    } else if (!m_searchViewportFilled) {
+        QTimer::singleShot(0, this, [this] {
             QScrollBar *bar = m_playlistList->verticalScrollBar();
-    if (bar && bar->maximum() == 0 && m_playlistOffset < m_playlistTotal)
-        requestPlaylistsPage(m_lastPlaylistGenreIds, m_lastPlaylistType, m_lastPlaylistTags, m_lastPlaylistQuery, m_playlistOffset, true);
+            if (bar && bar->maximum() == 0 && m_playlistOffset < m_playlistTotal) {
+                requestPlaylistsPage(m_lastPlaylistGenreIds, m_lastPlaylistType,
+                                     m_lastPlaylistTags, m_lastPlaylistQuery,
+                                     m_playlistOffset, true);
+            } else {
+                m_searchViewportFilled = true;
+                m_loadMorePlaylistsBtn->setVisible(m_playlistOffset < m_playlistTotal);
+            }
+        });
+    } else {
+        m_loadMorePlaylistsBtn->setVisible(true);
+    }
 }
 
 void GenreBrowserView::onSelectionChanged()
@@ -571,6 +612,9 @@ void GenreBrowserView::requestPlaylistsPage(const QString &genreIds, const QStri
         m_loadingPlaylists = false;
         m_playlistOffset = 0;
         m_playlistTotal = 0;
+        m_loadMorePlaylistsBtn->hide();
+        if (type == QStringLiteral("search"))
+            m_searchViewportFilled = false;
     }
 
     m_lastPlaylistGenreIds = genreIds;
@@ -580,7 +624,7 @@ void GenreBrowserView::requestPlaylistsPage(const QString &genreIds, const QStri
     m_loadingPlaylists = true;
 
     if (type == QStringLiteral("search")) {
-        m_backend->searchPlaylists(query, 8, static_cast<quint32>(offset));
+        m_backend->searchPlaylists(query, 25, static_cast<quint32>(offset));
     } else if (type.startsWith(QStringLiteral("discover-"))) {
         m_backend->discoverPlaylists(genreIds, tags, 25, static_cast<quint32>(offset));
     } else {
@@ -608,6 +652,9 @@ void GenreBrowserView::onAlbumScroll(int value)
 
 void GenreBrowserView::onPlaylistScroll(int value)
 {
+    // Search results use a manual "Load more" button instead of infinite scroll.
+    if (m_lastPlaylistType == QStringLiteral("search"))
+        return;
     if (m_loadingPlaylists)
         return;
     if (m_playlistOffset >= m_playlistTotal)

src/view/genrebrowser.hpp

@@ -70,6 +70,8 @@ private:
     QStackedWidget *m_resultsStack = nullptr;
     AlbumListView *m_albumList = nullptr;
     QTreeWidget *m_playlistList = nullptr;
+    QPushButton *m_loadMorePlaylistsBtn = nullptr;
+    bool m_searchViewportFilled = false;
     BrowseMode m_mode = BrowseMode::Genres;
     bool m_genresLoaded = false;
     int m_lastGenreComboIndex = 0;