feat(hub): Videos and Music list their cards a page at a time

Previous/next arrows in the pinned toolbar, on group pages and in Search.
Page size is an account preference (Settings → Defaults), 50 by default,
10 to 200 in steps of 10.

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

24 files changed, 419 insertions, 82 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/api/users.py b/packages/meshbay-hub/src/meshbay_hub/api/users.py
index a74f6af..991a4f7 100644
--- a/packages/meshbay-hub/src/meshbay_hub/api/users.py
+++ b/packages/meshbay-hub/src/meshbay_hub/api/users.py
@@ -1198,6 +1198,7 @@ ALLOWED_PREF_KEYS = frozenset([
     "notifications_disabled",
     "default_tab",
     "music_keep_screen_on",
+    "media_page_size",
 ])
 
 # `default_tab:<group_id>`, which is what the SPA writes (group-page.js). The
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/group-page.js b/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
index 51e39dc..4de33b9 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
@@ -760,7 +760,7 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
     // wire too, so nothing anywhere carries them.
     ...perAppDirectories,
     tmdbConfig,
-    musicbrainzConfig, onPlayQueue,
+    musicbrainzConfig, onPlayQueue, userPrefs,
   };
 
   return html`
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/icon.js b/packages/meshbay-hub/src/meshbay_hub/static/icon.js
index 90d9194..f45d339 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/icon.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/icon.js
@@ -64,6 +64,8 @@ const ICON_PATHS = {
              'M14.5 6.5l3 3'],
   check:    ['M4.5 12.5l5 5 10-11'],
   chevron:  ['M6 9.5l6 6 6-6'],
+  'chevron-left':  ['M14.5 6l-6 6 6 6'],
+  'chevron-right': ['M9.5 6l6 6-6 6'],
   close:    ['M6 6l12 12M18 6L6 18'],
   chat:     ['M21 15a2 2 0 0 1-2 2H7l-4 4V5a2 2 0 0 1 2-2h14a2 2 0 0 1 2 2z'],
   folder:   ['M3.5 6.6a1 1 0 0 1 1-1h4.2l2 2.4h7.8a1 1 0 0 1 1 1v9.4a1 1 0 0 1-1 1h-14a1 1 0 0 1-1-1z'],
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/de.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/de.js
index 6e5afa6..c705588 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/de.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/de.js
@@ -256,6 +256,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} von {total}',
+  'pager.previous': 'Vorherige Seite',
+  'pager.next': 'Nächste Seite',
   'video.empty': 'Keine Videos gefunden.',
   'video.no_root_configured': 'Für diese Gruppe ist noch kein Videos-Stammordner festgelegt — ein Operator kann in den Einstellungen einen auswählen.',
   'music.no_root_configured': 'Für diese Gruppe ist noch kein Musik-Stammordner festgelegt — ein Operator kann in den Einstellungen einen auswählen.',
@@ -365,6 +368,8 @@ export default {
   'settings.defaults': 'Standardwerte',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': 'Einträge pro Seite in Videos und Musik',
+  'settings.media_page_size_hint': 'Wie viele Poster oder Alben auf einmal angezeigt werden; die Pfeile in der Werkzeugleiste blättern weiter.',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'Node-Identitäten',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
index 7ffbc28..4f0fff2 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
@@ -254,6 +254,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} of {total}',
+  'pager.previous': 'Previous page',
+  'pager.next': 'Next page',
   'video.empty': 'No videos found.',
   'video.no_root_configured': 'No Videos root folder is set for this group yet — an operator can choose one in Settings.',
   'music.no_root_configured': 'No Music root folder is set for this group yet — an operator can choose one in Settings.',
@@ -362,6 +365,8 @@ export default {
   'settings.defaults': 'Defaults',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': 'Items per page in Videos and Music',
+  'settings.media_page_size_hint': 'How many posters or albums are shown at once; the arrows in the toolbar move to the next batch.',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'Node identities',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/es.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/es.js
index e675e10..fa0b0b2 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/es.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/es.js
@@ -254,6 +254,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} de {total}',
+  'pager.previous': 'Página anterior',
+  'pager.next': 'Página siguiente',
   'video.empty': 'No se encontraron vídeos.',
   'video.no_root_configured': 'Aún no se ha definido una carpeta raíz de Vídeos para este grupo — un operador puede elegir una en Configuración.',
   'music.no_root_configured': 'Aún no se ha definido una carpeta raíz de Música para este grupo — un operador puede elegir una en Configuración.',
@@ -363,6 +366,8 @@ export default {
   'settings.defaults': 'Valores predeterminados',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': 'Elementos por página en Vídeos y Música',
+  'settings.media_page_size_hint': 'Cuántos pósters o álbumes se muestran a la vez; las flechas de la barra de herramientas pasan al siguiente grupo.',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'Identidades de los nodes',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
index cc0892d..b4145ce 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
@@ -255,6 +255,9 @@ export default {
   'video.filter_all': 'Tous',
   'video.filter_movies': 'Films',
   'video.filter_series': 'Séries',
+  'pager.range': '{from}–{to} sur {total}',
+  'pager.previous': 'Page précédente',
+  'pager.next': 'Page suivante',
   'video.empty': 'Aucune vidéo trouvée.',
   'video.no_root_configured': "Aucun dossier racine des Vidéos n'est encore défini pour ce groupe — un opérateur peut en choisir un dans les Paramètres.",
   'music.no_root_configured': 'Aucun dossier racine de Musique n\'est encore défini pour ce groupe — un opérateur peut en choisir un dans les Paramètres.',
@@ -364,6 +367,8 @@ export default {
   'settings.defaults': 'Valeurs par défaut',
   'settings.default_tab': 'Onglet par défaut',
   'settings.default_tab_hint': 'L\'onglet qui s\'ouvre en premier quand vous entrez dans un groupe.',
+  'settings.media_page_size': 'Éléments par page dans Vidéos et Musique',
+  'settings.media_page_size_hint': 'Nombre d\'affiches ou d\'albums affichés à la fois ; les flèches de la barre d\'outils passent à la tranche suivante.',
   'settings.music_keep_screen_on': 'Garder l\'écran allumé pendant l\'écoute',
   'settings.music_keep_screen_on_hint': 'Empêche le téléphone de se verrouiller automatiquement pendant qu\'un morceau joue.',
   'settings.node_pins': 'Identités des nodes',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
index 7ccaff4..673f0cc 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
@@ -255,6 +255,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} di {total}',
+  'pager.previous': 'Pagina precedente',
+  'pager.next': 'Pagina successiva',
   'video.empty': 'Nessun video trovato.',
   'video.no_root_configured': 'Per questo gruppo non è ancora impostata una cartella radice di Video — un operatore può sceglierne una nelle Impostazioni.',
   'music.no_root_configured': 'Per questo gruppo non è ancora impostata una cartella radice di Musica — un operatore può sceglierne una nelle Impostazioni.',
@@ -364,6 +367,8 @@ export default {
   'settings.defaults': 'Valori predefiniti',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': 'Elementi per pagina in Video e Musica',
+  'settings.media_page_size_hint': 'Quanti poster o album vengono mostrati alla volta; le frecce nella barra degli strumenti passano al gruppo successivo.',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'Identità dei node',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
index aaec812..c36f2c9 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
@@ -252,6 +252,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} / {total}',
+  'pager.previous': '前のページ',
+  'pager.next': '次のページ',
   'video.empty': '動画が見つかりません。',
   'video.no_root_configured': 'このグループにはまだ動画のルートフォルダが設定されていません — 操作者が設定画面で選択できます。',
   'music.no_root_configured': 'このグループにはまだ音楽のルートフォルダが設定されていません — 操作者が設定画面で選択できます。',
@@ -361,6 +364,8 @@ export default {
   'settings.defaults': 'デフォルト',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': 'ビデオと音楽の1ページあたりの表示数',
+  'settings.media_page_size_hint': '一度に表示するポスターやアルバムの数。ツールバーの矢印で次のまとまりに移動します。',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'node の識別情報',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
index 3049cef..180c1bb 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
@@ -256,6 +256,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} van {total}',
+  'pager.previous': 'Vorige pagina',
+  'pager.next': 'Volgende pagina',
   'video.empty': "Geen video's gevonden.",
   'video.no_root_configured': "Er is nog geen hoofdmap voor Video's ingesteld voor deze groep — een operator kan er een kiezen bij Instellingen.",
   'music.no_root_configured': 'Er is nog geen hoofdmap voor Muziek ingesteld voor deze groep — een operator kan er een kiezen bij Instellingen.',
@@ -365,6 +368,8 @@ export default {
   'settings.defaults': 'Standaardwaarden',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': 'Items per pagina in Video\'s en Muziek',
+  'settings.media_page_size_hint': 'Hoeveel posters of albums tegelijk worden getoond; de pijlen in de werkbalk gaan naar de volgende reeks.',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'Node-identiteiten',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/pl.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/pl.js
index 8922d0a..180cdbe 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/pl.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/pl.js
@@ -261,6 +261,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} z {total}',
+  'pager.previous': 'Poprzednia strona',
+  'pager.next': 'Następna strona',
   'video.empty': 'Nie znaleziono żadnych filmów.',
   'video.no_root_configured': 'Dla tej grupy nie wybrano jeszcze katalogu głównego Wideo — operator może go wybrać w Ustawieniach.',
   'music.no_root_configured': 'Dla tej grupy nie wybrano jeszcze katalogu głównego Muzyki — operator może go wybrać w Ustawieniach.',
@@ -376,6 +379,8 @@ export default {
   'settings.defaults': 'Wartości domyślne',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': 'Elementy na stronę w Wideo i Muzyce',
+  'settings.media_page_size_hint': 'Ile plakatów lub albumów jest wyświetlanych naraz; strzałki na pasku narzędzi przechodzą do kolejnej porcji.',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'Tożsamości nodes',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/pt-BR.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/pt-BR.js
index 460a902..2ae26b2 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/pt-BR.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/pt-BR.js
@@ -256,6 +256,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} de {total}',
+  'pager.previous': 'Página anterior',
+  'pager.next': 'Próxima página',
   'video.empty': 'Nenhum vídeo encontrado.',
   'video.no_root_configured': 'Ainda não há uma pasta raiz de Vídeos definida para este grupo — um operador pode escolher uma em Configurações.',
   'music.no_root_configured': 'Ainda não há uma pasta raiz de Música definida para este grupo — um operador pode escolher uma em Configurações.',
@@ -365,6 +368,8 @@ export default {
   'settings.defaults': 'Padrões',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': 'Itens por página em Vídeos e Música',
+  'settings.media_page_size_hint': 'Quantos pôsteres ou álbuns são exibidos de uma vez; as setas na barra de ferramentas passam para o próximo lote.',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'Identidades dos nodes',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/zh-CN.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/zh-CN.js
index b8ab4ef..6c0ec37 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/zh-CN.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/zh-CN.js
@@ -249,6 +249,9 @@ export default {
   'video.filter_all': 'All',
   'video.filter_movies': 'Movies',
   'video.filter_series': 'Series',
+  'pager.range': '{from}–{to} / 共 {total}',
+  'pager.previous': '上一页',
+  'pager.next': '下一页',
   'video.empty': '未找到视频。',
   'video.no_root_configured': '此群组尚未设置视频根目录 — 操作员可以在设置中选择一个。',
   'music.no_root_configured': '此群组尚未设置音乐根目录 — 操作员可以在设置中选择一个。',
@@ -357,6 +360,8 @@ export default {
   'settings.defaults': '默认值',
   'settings.default_tab': 'Default tab',
   'settings.default_tab_hint': 'Which tab opens first when you enter a group.',
+  'settings.media_page_size': '视频和音乐每页显示数量',
+  'settings.media_page_size_hint': '一次显示多少张海报或专辑；工具栏中的箭头可切换到下一批。',
   'settings.music_keep_screen_on': 'Keep screen on during music playback',
   'settings.music_keep_screen_on_hint': 'Prevents the phone from locking on its own while a track is playing.',
   'settings.node_pins': 'node 身份',
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/music-app.js b/packages/meshbay-hub/src/meshbay_hub/static/music-app.js
index f622b5d..60a7b00 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/music-app.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/music-app.js
@@ -6,6 +6,7 @@ import { Icon } from './icon.js';
 import { MediaThumb, LazyTile } from './video-app.js';
 import { formatTime } from './music-player.js';
 import { SourceTag } from './group-name.js';
+import { usePager, Pager, pageSizeFrom } from './pager.js';
 
 // -- Music --------------------------------------------------------------------
 //
@@ -324,8 +325,16 @@ function MusicDetailModal({ album, transportRef, gekRef, musicbrainzEnabled, onC
 
 // -- Mode A: album grid -----------------------------------------------------
 
-function AlbumGrid({ artists, transportRef, gekRef, musicbrainzEnabled, onPlayQueue }) {
+// `units` is one page of `{ artist, album }`. An artist whose albums straddle
+// two pages gets its heading on both.
+function AlbumGrid({ units, transportRef, gekRef, musicbrainzEnabled, onPlayQueue }) {
   const [detail, setDetail] = useState(null); // the album object
+  const artists = [];
+  for (const u of units) {
+    const prev = artists[artists.length - 1];
+    if (prev && prev.artist === u.artist) prev.albums.push(u.album);
+    else artists.push({ artist: u.artist, albums: [u.album] });
+  }
 
   return html`
     ${artists.map((a) => html`
@@ -435,12 +444,8 @@ function FlatArtistFolder({ artist, onPlayQueue }) {
   `;
 }
 
-function FlatList({ tracks, artists, onPlayQueue }) {
-  const items = [
-    ...tracks.map((tr) => ({ key: tr.display_title || tr.name, kind: 'track', track: tr })),
-    ...artists.map((a) => ({ key: a.artist, kind: 'artist', artist: a })),
-  ].sort((a, b) => a.key.localeCompare(b.key));
-
+// `items` is one page of rows, already sorted by MusicApp.
+function FlatList({ items, onPlayQueue }) {
   return html`
     <div class="video-flat-list">
       ${items.map((it) => it.kind === 'track'
@@ -456,7 +461,7 @@ function FlatList({ tracks, artists, onPlayQueue }) {
 function MusicApp({
   groupId, transportRef, gekRef, status, entries, availableEntries,
   musicDirectories, musicbrainzConfig, onPlayQueue,
-  hideFilter,
+  hideFilter, userPrefs, pageResetKey,
 }) {
   const [mode, setMode] = useState(loadViewMode);
   const [filter, setFilter] = useState('');
@@ -488,6 +493,24 @@ function MusicApp({
   const filteredTracks = useMemo(() => (!needle ? tracks : tracks.filter(
     (tr) => (tr.display_title || tr.name).toLowerCase().includes(needle))), [tracks, needle]);
 
+  // What this mode draws, in drawing order: albums under their artists in the
+  // grid, and in the flat list loose tracks and artist folders sorted together.
+  const units = useMemo(() => {
+    if (mode === 'grid') {
+      return filteredArtists.flatMap((a) => a.albums.map((album) => ({ artist: a.artist, album })));
+    }
+    return [
+      ...filteredTracks.map((tr) => ({ key: tr.display_title || tr.name, kind: 'track', track: tr })),
+      ...filteredArtists.map((a) => ({ key: a.artist, kind: 'artist', artist: a })),
+    ].sort((a, b) => a.key.localeCompare(b.key));
+  }, [mode, filteredArtists, filteredTracks]);
+
+  const pager = usePager(units.length, pageSizeFrom(userPrefs),
+    `${groupId}|${mode}|${needle}|${pageResetKey || ''}`);
+  const pageUnits = useMemo(() => {
+    return units.slice(pager.start, pager.end);
+  }, [units, pager.start, pager.end]);
+
   const empty = albums.length === 0 && tracks.length === 0;
 
   return html`
@@ -510,6 +533,7 @@ function MusicApp({
           onClick=${() => setModeAndSave('flat')}>
           ${t('music.mode_flat')}
         </button>
+        <${Pager} pager=${pager} />
         ${!hideFilter && html`<div class="tb-search">
           <${Icon} name="search" />
           <input type="text" placeholder="${t('group.filter')}"
@@ -521,9 +545,9 @@ function MusicApp({
         <p class="page-message">${t('group.empty_filter')}</p>
       `}
       ${!empty && mode === 'grid'
-        ? html`<${AlbumGrid} artists=${filteredArtists} transportRef=${transportRef} gekRef=${gekRef}
+        ? html`<${AlbumGrid} units=${pageUnits} transportRef=${transportRef} gekRef=${gekRef}
                 musicbrainzEnabled=${musicbrainzEnabled} onPlayQueue=${onPlayQueue} />`
-        : !empty && html`<${FlatList} tracks=${filteredTracks} artists=${filteredArtists}
+        : !empty && html`<${FlatList} items=${pageUnits}
                 onPlayQueue=${onPlayQueue} />`}
     `}
   `;
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/pager.js b/packages/meshbay-hub/src/meshbay_hub/static/pager.js
new file mode 100644
index 0000000..a5c165b
--- /dev/null
+++ b/packages/meshbay-hub/src/meshbay_hub/static/pager.js
@@ -0,0 +1,89 @@
+import {
+  html, useState, useRef, useCallback,
+} from './vendor/htm-preact.js';
+import { t } from './i18n.js';
+import { Icon } from './icon.js';
+
+// ── Pages of cards ───────────────────────────────────────────────────────────
+//
+// Videos and Music draw one card per film, show or album, and a library of a
+// few thousand is a very long scroll. They show a slice at a time instead,
+// with arrows in their pinned toolbar. The slice is cut from the list exactly
+// as it would have been drawn, so paging never reorders anything.
+//
+// The size is the reader's own preference, kept on the hub with the others
+// (Settings → Defaults). `PAGE_SIZE_PREF` must be in the hub's
+// `ALLOWED_PREF_KEYS`, or saving it is a 400 nobody sees.
+
+export const PAGE_SIZE_PREF = 'media_page_size';
+export const PAGE_SIZE_DEFAULT = 50;
+export const PAGE_SIZE_STEP = 10;
+export const PAGE_SIZE_MAX = 200;
+
+// Anything that is not a multiple of the step within range reads as the
+// default: the value is a string the hub stores without looking at it.
+export function pageSizeFrom(userPrefs) {
+  const n = Number(userPrefs && userPrefs[PAGE_SIZE_PREF]);
+  if (!Number.isInteger(n) || n < PAGE_SIZE_STEP || n > PAGE_SIZE_MAX || n % PAGE_SIZE_STEP) {
+    return PAGE_SIZE_DEFAULT;
+  }
+  return n;
+}
+
+// Clamped rather than reset when the list shrinks under the reader — Search
+// loses a group's cards while it reconnects — so the page comes back once
+// they do.
+export function pageBounds(total, size, page) {
+  const last = Math.max(0, Math.ceil(total / size) - 1);
+  const current = Math.min(Math.max(0, page), last);
+  return { page: current, last, start: current * size, end: Math.min(total, (current + 1) * size) };
+}
+
+// `resetKey` names what the list is (group, mode, filter, query): a different
+// list starts on its first page. Compared during render rather than reset by an
+// effect, which would draw the old page of the new list for one frame.
+export function usePager(total, size, resetKey) {
+  const key = `${resetKey}|${size}`;
+  const [state, setState] = useState({ key, page: 0 });
+  const bounds = pageBounds(total, size, state.key === key ? state.page : 0);
+  const setPage = useCallback((page) => {
+    setState({ key, page });
+  }, [key]);
+  return { ...bounds, total, size, setPage };
+}
+
+// A new page starts at the top of the list, not wherever the previous one was
+// scrolled to. Only ever upwards, and only as far as the list's first row
+// sitting under the pinned toolbar, so a reader who has not scrolled is not
+// moved. The toolbar is the pager's parent and the list its next sibling —
+// the structure style.css's "Sticky chrome" already requires.
+function keepListInView(el) {
+  const toolbar = el && el.parentElement;
+  const list = toolbar && toolbar.nextElementSibling;
+  if (!list) return;
+  const gap = parseFloat(getComputedStyle(toolbar).marginBottom) || 0;
+  const target = window.scrollY + list.getBoundingClientRect().top
+    - toolbar.getBoundingClientRect().bottom - gap;
+  if (target < window.scrollY) window.scrollTo(0, Math.max(0, target));
+}
+
+export function Pager({ pager }) {
+  const ref = useRef(null);
+  if (pager.total <= pager.size) return null;
+  const go = (page) => { keepListInView(ref.current); pager.setPage(page); };
+  return html`
+    <div class="tb-pager" ref=${ref}>
+      <button class="tb-btn tb-btn-icon" disabled=${pager.page === 0}
+        title=${t('pager.previous')} aria-label=${t('pager.previous')}
+        onClick=${() => go(pager.page - 1)}>
+        <${Icon} name="chevron-left" /></button>
+      <span class="tb-pager-range">
+        ${t('pager.range', { from: pager.start + 1, to: pager.end, total: pager.total })}
+      </span>
+      <button class="tb-btn tb-btn-icon" disabled=${pager.page === pager.last}
+        title=${t('pager.next')} aria-label=${t('pager.next')}
+        onClick=${() => go(pager.page + 1)}>
+        <${Icon} name="chevron-right" /></button>
+    </div>
+  `;
+}
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/search-page.js b/packages/meshbay-hub/src/meshbay_hub/static/search-page.js
index 45a436e..3759650 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/search-page.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/search-page.js
@@ -776,6 +776,7 @@ function SearchPage({ token, username, userId, groups, onPlayQueue, userPrefs })
           tmdbConfig=${{ enabled: true }}
           isNodeAdmin=${false}
           onNeedConn=${connectGroup}
+          userPrefs=${userPrefs} pageResetKey=${q}
           hideFilter=${true} />
       `}
 
@@ -789,6 +790,7 @@ function SearchPage({ token, username, userId, groups, onPlayQueue, userPrefs })
           musicDirectories=${[SEARCH_AUDIO_ROOT]}
           musicbrainzConfig=${{ enabled: true }}
           onPlayQueue=${handleMusicPlay}
+          userPrefs=${userPrefs} pageResetKey=${q}
           hideFilter=${true} />
       `}
 
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/settings-page.js b/packages/meshbay-hub/src/meshbay_hub/static/settings-page.js
index c6a73da..51d99cd 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/settings-page.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/settings-page.js
@@ -6,6 +6,12 @@ import * as downloads from './downloads.js';
 import * as platform from './platform.js';
 import { hubFetch } from './hub-client.js';
 import { APPS } from './apps.js';
+import {
+  PAGE_SIZE_PREF, PAGE_SIZE_DEFAULT, PAGE_SIZE_STEP, PAGE_SIZE_MAX, pageSizeFrom,
+} from './pager.js';
+
+const PAGE_SIZES = Array.from(
+  { length: PAGE_SIZE_MAX / PAGE_SIZE_STEP }, (_, i) => (i + 1) * PAGE_SIZE_STEP);
 
 export function SettingsPage({ user, theme, onThemeChange, groups, onPrefsChange }) {
   const [locale, setLoc] = useState(getLocale);
@@ -19,6 +25,7 @@ export function SettingsPage({ user, theme, onThemeChange, groups, onPrefsChange
   // e.g. to ride out the WebRTC screen-lock reconnect gap without waiting
   // on the automatic recovery at all.
   const [keepScreenOnAudio, setKeepScreenOnAudio] = useState(false);
+  const [pageSize, setPageSize] = useState(PAGE_SIZE_DEFAULT);
 
   const onLocaleChange = useCallback((e) => {
     const code = e.target.value;
@@ -37,6 +44,7 @@ export function SettingsPage({ user, theme, onThemeChange, groups, onPrefsChange
         if (prefs.notifications_disabled === 'true') setGlobalMute(true);
         if (prefs.default_tab) setDefaultTab(prefs.default_tab);
         if (prefs.music_keep_screen_on === 'true') setKeepScreenOnAudio(true);
+        setPageSize(pageSizeFrom(prefs));
       })
       .catch(() => {});
   }, [user.token]);
@@ -97,6 +105,18 @@ export function SettingsPage({ user, theme, onThemeChange, groups, onPrefsChange
     } catch { setDefaultTab(defaultTab); }
   }, [defaultTab, user.token, onPrefsChange]);
 
+  const changePageSize = useCallback(async (e) => {
+    const val = String(e.target.value);
+    setPageSize(Number(val));
+    try {
+      await hubFetch(`/v1/users/me/preferences/${PAGE_SIZE_PREF}`, {
+        method: 'PUT', token: user.token,
+        body: { value: val },
+      });
+      if (onPrefsChange) onPrefsChange({ [PAGE_SIZE_PREF]: val });
+    } catch { setPageSize(pageSize); }
+  }, [pageSize, user.token, onPrefsChange]);
+
   const [dlMode, setDlMode] = useState(() => downloads.getMode());
   const [dlDir, setDlDir] = useState(null);
   const [dlError, setDlError] = useState('');
@@ -249,6 +269,14 @@ export function SettingsPage({ user, theme, onThemeChange, groups, onPrefsChange
         </div>
         <p class="settings-hint">${t('settings.default_tab_hint')}</p>
         <div class="settings-row">
+          <span class="settings-label">${t('settings.media_page_size')}</span>
+          <select class="settings-select" value=${pageSize}
+            onChange=${changePageSize}>
+            ${PAGE_SIZES.map((n) => html`<option key=${n} value=${n}>${n}</option>`)}
+          </select>
+        </div>
+        <p class="settings-hint">${t('settings.media_page_size_hint')}</p>
+        <div class="settings-row">
           <span class="settings-label">${t('settings.music_keep_screen_on')}</span>
           <label class="toggle-switch">
             <input type="checkbox" checked=${keepScreenOnAudio}
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/style.css b/packages/meshbay-hub/src/meshbay_hub/static/style.css
index bae1a82..049db0f 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/style.css
+++ b/packages/meshbay-hub/src/meshbay_hub/static/style.css
@@ -3613,6 +3613,24 @@ h2 .gn-owner, h3 .gn-owner { font-size: 0.55em; }
 }
 .video-toolbar .tb-search { margin-left: auto; }
 
+/* The page arrows (pager.js): pushed to the right edge, just before the filter
+   when there is one — on a phone the filter wraps onto its own line and the
+   arrows stay with the controls. */
+.video-toolbar .tb-pager { margin-left: auto; }
+.video-toolbar .tb-pager + .tb-search { margin-left: 0; }
+.tb-pager {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  flex-shrink: 0;
+}
+.tb-pager-range {
+  font-size: 0.83em;
+  color: var(--text-dim);
+  white-space: nowrap;
+  font-variant-numeric: tabular-nums;
+}
+
 /* All/Movies/Series — a segmented control, not three separate .tb-btn: the
    three are mutually exclusive (unlike the view-mode buttons, which read
    fine standalone), and grouping them under one shared border is what says
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/video-app.js b/packages/meshbay-hub/src/meshbay_hub/static/video-app.js
index 18b99af..d4af4ef 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/video-app.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/video-app.js
@@ -5,6 +5,7 @@ import { t } from './i18n.js';
 import { Icon } from './icon.js';
 import { formatSize, pipelinedDownload } from './file-utils.js';
 import { SourceTag } from './group-name.js';
+import { usePager, Pager, pageSizeFrom } from './pager.js';
 
 // ── Videos ───────────────────────────────────────────────────────────────────
 //
@@ -845,60 +846,61 @@ function VideoDetailModal({
   `;
 }
 
+// Two raw groups (grouped by parsed display_title, §4.1) resolving to the
+// same confident TMDB id are almost certainly one show whose seasons
+// were released under differently-named folders — confirmed live: one
+// operator's show had its two seasons parsed as two spellings by
+// two different release groups, showing as two identical-looking cards
+// once both matched the same real show (§3.4/V6). Merged here once both
+// are actually known — never required for the fallback to work: a group
+// with no confident match yet, or ever, still shows on its own, exactly
+// the generic per-folder display needs.
+//
+// Called by VideoApp rather than by the grid: a page is cut from the merged
+// list, so a show has to be one card before it is counted. A merge still needs
+// both halves to have been on screen, since only a mounted card reports its
+// match.
+function mergeShowsByTmdb(shows, metaByGroup) {
+  const byTmdbId = new Map();
+  const standalone = [];
+  for (const s of shows) {
+    const meta = metaByGroup[s.title];
+    const tmdbId = meta && meta.confidence && meta.tmdb_id;
+    if (tmdbId) {
+      if (!byTmdbId.has(tmdbId)) byTmdbId.set(tmdbId, []);
+      byTmdbId.get(tmdbId).push(s);
+    } else {
+      standalone.push([s]);
+    }
+  }
+  return [...byTmdbId.values(), ...standalone].map((groups) => {
+    const episodes = groups.flatMap((g) => g.episodes);
+    return {
+      // groups[0].title, not a joined string of every constituent's
+      // title: a fresh key here would make this a brand-new PosterCard
+      // (and LazyTile) the instant a second raw group merges into an
+      // already-visible one — throwing away its already-fired
+      // IntersectionObserver and already-resolved metadata/poster for no
+      // reason, and reintroducing exactly the flash the "ready" gating
+      // above exists to prevent. groups[0].title is already unique
+      // (raw titles are, via groupVideoEntries' showsByTitle) and, for
+      // the overwhelmingly common unmerged case, is the same key the
+      // card already had — so nothing about this changes when no merge
+      // ever happens.
+      key: groups[0].title,
+      title: groups[0].title,
+      episodes,
+      seasons: buildSeasons(episodes),
+    };
+  });
+}
+
+// `units` is one page of cards, in drawing order: `{ kind: 'movie', entry }`
+// or `{ kind: 'show', show }`.
 function PosterGrid({
-  movies, shows, transportRef, gekRef, onPreview, tmdbEnabled, isNodeAdmin, onNeedConn,
+  units, transportRef, gekRef, onPreview, tmdbEnabled, isNodeAdmin, onNeedConn, onMetaResolved,
 }) {
   const [detail, setDetail] = useState(null); // { title, repEntry, show? }
-  // raw (per-folder-parsed-title) show title -> its own resolved media_meta_resp.
-  const [metaByGroup, setMetaByGroup] = useState({});
-
-  const handleMetaResolved = useCallback((groupKey, meta) => {
-    setMetaByGroup((prev) => (prev[groupKey] === meta ? prev : { ...prev, [groupKey]: meta }));
-  }, []);
-
-  // Two raw groups (grouped by parsed display_title, §4.1) resolving to the
-  // same confident TMDB id are almost certainly one show whose seasons
-  // were released under differently-named folders — confirmed live: one
-  // operator's show had its two seasons parsed as two spellings by
-  // two different release groups, showing as two identical-looking cards
-  // once both matched the same real show (§3.4/V6). Merged here once both
-  // are actually known — never required for the fallback to work: a group
-  // with no confident match yet, or ever, still shows on its own, exactly
-  // the generic per-folder display needs.
-  const mergedShows = useMemo(() => {
-    const byTmdbId = new Map();
-    const standalone = [];
-    for (const s of shows) {
-      const meta = metaByGroup[s.title];
-      const tmdbId = meta && meta.confidence && meta.tmdb_id;
-      if (tmdbId) {
-        if (!byTmdbId.has(tmdbId)) byTmdbId.set(tmdbId, []);
-        byTmdbId.get(tmdbId).push(s);
-      } else {
-        standalone.push([s]);
-      }
-    }
-    return [...byTmdbId.values(), ...standalone].map((groups) => {
-      const episodes = groups.flatMap((g) => g.episodes);
-      return {
-        // groups[0].title, not a joined string of every constituent's
-        // title: a fresh key here would make this a brand-new PosterCard
-        // (and LazyTile) the instant a second raw group merges into an
-        // already-visible one — throwing away its already-fired
-        // IntersectionObserver and already-resolved metadata/poster for no
-        // reason, and reintroducing exactly the flash the "ready" gating
-        // above exists to prevent. groups[0].title is already unique
-        // (raw titles are, via groupVideoEntries' showsByTitle) and, for
-        // the overwhelmingly common unmerged case, is the same key the
-        // card already had — so nothing about this changes when no merge
-        // ever happens.
-        key: groups[0].title,
-        title: groups[0].title,
-        episodes,
-        seasons: buildSeasons(episodes),
-      };
-    });
-  }, [shows, metaByGroup]);
 
   const openDetail = (title, repEntry, show) => setDetail({ title, repEntry, show });
   const detailTRef = detail && detail.repEntry._tRef ? detail.repEntry._tRef : transportRef;
@@ -910,8 +912,11 @@ function PosterGrid({
 
   return html`
     <div class="video-grid">
-      ${movies.map((e) => html`
-        <${LazyTile} key=${e.id}>
+      ${units.map((u) => {
+        if (u.kind === 'movie') {
+          const e = u.entry;
+          return html`
+        <${LazyTile} key=${u.key}>
           <${PosterCard} title=${e.display_title || e.name}
             subtitle=${formatDuration(e.duration)} repEntry=${e}
             groupKey=${`movie:${e.id}`}
@@ -926,8 +931,9 @@ function PosterGrid({
               ? openDetail(e.display_title || e.name, e, null)
               : onPreview(e))} />
         </${LazyTile}>
-      `)}
-      ${mergedShows.map((s) => {
+      `;
+        }
+        const s = u.show;
         // Prefer an episode that actually has a thumbnail over blindly
         // episodes[0]: if that specific file's enrichment hasn't produced
         // one yet (or failed), the card showed an empty placeholder even
@@ -945,13 +951,13 @@ function PosterGrid({
           ? (singleSeason === 0 ? t('video.specials') : t('video.season_n', { n: singleSeason }))
           : t('video.n_episodes', { n: s.episodes.length });
         return html`
-        <${LazyTile} key=${s.key}>
+        <${LazyTile} key=${u.key}>
           <${PosterCard} title=${s.title}
             subtitle=${subtitle}
             repEntry=${repEntry}
             sourceEntries=${s.episodes}
             groupKey=${s.title}
-            onMetaResolved=${handleMetaResolved}
+            onMetaResolved=${onMetaResolved}
             onNeedConn=${onNeedConn} tmdbEnabled=${tmdbEnabled}
             transportRef=${transportRef} gekRef=${gekRef}
             onOpen=${() => openDetail(s.title, repEntry, s)} />
@@ -1042,12 +1048,8 @@ function FlatShowFolder({ show, transportRef, gekRef, onPreview, onNeedConn }) {
   `;
 }
 
-function FlatList({ movies, shows, transportRef, gekRef, onPreview, onNeedConn }) {
-  const items = [
-    ...movies.map((e) => ({ key: e.display_title || e.name, kind: 'movie', entry: e })),
-    ...shows.map((s) => ({ key: s.title, kind: 'show', show: s })),
-  ].sort((a, b) => a.key.localeCompare(b.key));
-
+// `items` is one page of rows, already sorted by VideoApp.
+function FlatList({ items, transportRef, gekRef, onPreview, onNeedConn }) {
   return html`
     <div class="video-flat-list">
       ${items.map((it) => it.kind === 'movie'
@@ -1066,10 +1068,12 @@ function FlatList({ movies, shows, transportRef, gekRef, onPreview, onNeedConn }
 function VideoApp({
   groupId, transportRef, gekRef, status, entries, availableEntries, onPreview,
   videoDirectories, tmdbConfig, isNodeAdmin,
-  hideFilter, onNeedConn,
+  hideFilter, onNeedConn, userPrefs, pageResetKey,
 }) {
   const [mode, setMode] = useState(loadViewMode);
   const [filter, setFilter] = useState('');
+  // raw (per-folder-parsed-title) show title -> its own resolved media_meta_resp.
+  const [metaByGroup, setMetaByGroup] = useState({});
   // Which of movies/shows to show at all — independent of the text filter
   // below, and applied first: a title match within a type nobody asked to
   // see is still not what "Movies only" means.
@@ -1095,6 +1099,34 @@ function VideoApp({
   const filteredShows = useMemo(() => (typeFilter === 'movies' ? [] : !needle ? shows : shows.filter(
     (s) => s.title.toLowerCase().includes(needle))), [shows, needle, typeFilter]);
 
+  const handleMetaResolved = useCallback((groupKey, meta) => {
+    setMetaByGroup((prev) => (prev[groupKey] === meta ? prev : { ...prev, [groupKey]: meta }));
+  }, []);
+  const mergedShows = useMemo(() => {
+    return mergeShowsByTmdb(filteredShows, metaByGroup);
+  }, [filteredShows, metaByGroup]);
+
+  // Everything this mode would draw, in the order it draws it, so a page is
+  // exactly a stretch of what the reader would otherwise have scrolled. The
+  // flat list sorts films and shows together and does not merge.
+  const units = useMemo(() => {
+    const movieUnits = filteredMovies.map((e) => ({
+      kind: 'movie', key: `movie:${e.id}`, sortKey: e.display_title || e.name, entry: e }));
+    if (mode === 'poster') {
+      return [...movieUnits,
+              ...mergedShows.map((s) => ({ kind: 'show', key: `show:${s.key}`, show: s }))];
+    }
+    return [...movieUnits,
+            ...filteredShows.map((s) => ({ kind: 'show', key: `show:${s.title}`, sortKey: s.title, show: s }))]
+      .sort((a, b) => a.sortKey.localeCompare(b.sortKey));
+  }, [mode, filteredMovies, filteredShows, mergedShows]);
+
+  const pager = usePager(units.length, pageSizeFrom(userPrefs),
+    `${groupId}|${mode}|${typeFilter}|${needle}|${pageResetKey || ''}`);
+  const pageUnits = useMemo(() => {
+    return units.slice(pager.start, pager.end);
+  }, [units, pager.start, pager.end]);
+
   return html`
     ${(status === 'discovering' || status === 'connecting' || status === 'fetching') && html`
       <p class="page-message"><span class="spinner"></span>${' '}${t('status.connecting_short')}</p>
@@ -1129,6 +1161,7 @@ function VideoApp({
             ${t('video.filter_series')}
           </button>
         </div>
+        <${Pager} pager=${pager} />
         ${!hideFilter && html`<div class="tb-search">
           <${Icon} name="search" />
           <input type="text" placeholder="${t('group.filter')}"
@@ -1139,10 +1172,10 @@ function VideoApp({
         <p class="page-message">${needle ? t('group.empty_filter') : t('video.empty')}</p>
       `}
       ${mode === 'poster'
-        ? html`<${PosterGrid} movies=${filteredMovies} shows=${filteredShows}
+        ? html`<${PosterGrid} units=${pageUnits} onMetaResolved=${handleMetaResolved}
                 transportRef=${transportRef} gekRef=${gekRef} onPreview=${onPreview}
                 tmdbEnabled=${tmdbEnabled} isNodeAdmin=${isNodeAdmin} onNeedConn=${onNeedConn} />`
-        : html`<${FlatList} movies=${filteredMovies} shows=${filteredShows}
+        : html`<${FlatList} items=${pageUnits}
                 transportRef=${transportRef} gekRef=${gekRef} onPreview=${onPreview}
                 onNeedConn=${onNeedConn} />`}
     `}
diff --git a/packages/meshbay-hub/tests/harness/sticky_header_probe.py b/packages/meshbay-hub/tests/harness/sticky_header_probe.py
index 320a2d4..ee1e61b 100755
--- a/packages/meshbay-hub/tests/harness/sticky_header_probe.py
+++ b/packages/meshbay-hub/tests/harness/sticky_header_probe.py
@@ -185,7 +185,11 @@ for (let i = 0; i < 40; i++)
   add({ name: `${ARTISTS[i % ARTISTS.length]} au Zenith (2019) 1080p.mkv`,
         path: 'films', type: 'video',
         display_title: `${ARTISTS[i % ARTISTS.length]} au Zenith` });
-for (let a = 0; a < 20; a++)
+// Forty films and forty albums against a page of thirty, so Videos and Music
+// draw their page arrows in the toolbar being measured (pager.js) — a band
+// that only ever gets them past fifty would never be measured with them.
+const PAGE_SIZE = '30';
+for (let a = 0; a < 40; a++)
   for (let t = 0; t < 2; t++)
     add({ name: `${t + 1} track.flac`,
           path: `musique/${ARTISTS[a % ARTISTS.length]} ${a}/disque ${t}`,
@@ -319,7 +323,7 @@ const settle = () => new Promise((r) =>
       render(html`<${GroupPage} groupId="g1" token="t" username="me" userId="u1"
         group=${{ id: 'g1', name: 'un groupe', owner_username: 'me',
                   is_admin: false }}
-        userPrefs=${{ default_tab: 'files' }} />`,
+        userPrefs=${{ default_tab: 'files', media_page_size: PAGE_SIZE }} />`,
         document.getElementById('root'));
     } else {
       render(html`<${SearchPage} token="t" username="me" userId="u1"
@@ -329,7 +333,7 @@ const settle = () => new Promise((r) =>
               not. */''}
         groups=${[{ id: 'g1', name: 'musique_de_la_maison_2024',
                     owner_username: 'cbesson' }]}
-        userPrefs=${{}} />`, document.getElementById('root'));
+        userPrefs=${{ media_page_size: PAGE_SIZE }} />`, document.getElementById('root'));
       // Results only exist once an index has arrived; the view toggle is drawn
       // with them.
       const field = await waitFor('.search-bar input');
@@ -377,6 +381,8 @@ const settle = () => new Promise((r) =>
       bottomScrollY: Math.round(scrollY),
       scrollY: scrolledBy, room: Math.round(room),
       overflowX: overflowX(),
+      // Whether the toolbar carried its page arrows while it was measured.
+      pager: !!document.querySelector('.video-toolbar > .tb-pager'),
       // Whether the Search page's group column is on screen. It is dropped at
       // phone widths, where the file name needs every pixel it can get.
       groupColumn: (() => {
diff --git a/packages/meshbay-hub/tests/test_hook_ordering.py b/packages/meshbay-hub/tests/test_hook_ordering.py
index 3e9c968..28ec93e 100644
--- a/packages/meshbay-hub/tests/test_hook_ordering.py
+++ b/packages/meshbay-hub/tests/test_hook_ordering.py
@@ -35,7 +35,7 @@ APP = STATIC / "app.js"
 STATIC_FILES = [
     "app.js", "group-page.js", "chat-app.js", "files-app.js",
     "video-player.js", "video-app.js", "music-app.js", "music-player.js",
-    "photos-app.js",
+    "photos-app.js", "pager.js",
     "group-settings.js",
     # The per-app settings architecture (docs/refactor-groups.md §3). Reached
     # through the apps.js registry rather than imported by name, so a file
diff --git a/packages/meshbay-hub/tests/test_media_pager.py b/packages/meshbay-hub/tests/test_media_pager.py
new file mode 100644
index 0000000..a8a0569
--- /dev/null
+++ b/packages/meshbay-hub/tests/test_media_pager.py
@@ -0,0 +1,71 @@
+"""
+Videos and Music show their cards a page at a time (`pager.js`).
+
+The page size is a hub preference, so two things can go wrong without any
+error on screen: a stored value the client misreads, and a key the hub refuses
+— the Settings select would snap back and nothing would say why. The functions
+are read out of `pager.js` rather than copied, and the key out of both files.
+"""
+
+import json
+import re
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parents[1] / "src" / "meshbay_hub"
+PAGER = ROOT / "static" / "pager.js"
+USERS = ROOT / "api" / "users.py"
+
+pytestmark = pytest.mark.skipif(
+    shutil.which("node") is None or not PAGER.exists(),
+    reason="node or the SPA sources are not available")
+
+
+@pytest.fixture(scope="module")
+def source():
+    text = PAGER.read_text(encoding="utf-8")
+    consts = re.findall(r"^export const PAGE_SIZE_\w+ = [^;]+;", text, re.M)
+    funcs = [re.search(rf"^export function {name}\(.*?^\}}", text, re.M | re.S)
+             for name in ("pageSizeFrom", "pageBounds")]
+    assert len(consts) == 4 and all(funcs), "pager.js no longer has what this test reads"
+    return "\n".join(consts + [m.group(0) for m in funcs]).replace("export ", "")
+
+
+def _run(tmp_path, source, expr):
+    script = tmp_path / "case.js"
+    script.write_text(f"{source}\nconsole.log(JSON.stringify({expr}));")
+    out = subprocess.run(["node", str(script)], capture_output=True, text=True, check=True)
+    return json.loads(out.stdout)
+
+
+@pytest.mark.parametrize("stored, expected", [
+    (None, 50), ("", 50), ("30", 30), ("10", 10), ("200", 200),
+    ("0", 50), ("210", 50), ("35", 50), ("abc", 50), ("-10", 50),
+])
+def test_page_size_from_preference(tmp_path, source, stored, expected):
+    prefs = {} if stored is None else {"media_page_size": stored}
+    assert _run(tmp_path, source, f"pageSizeFrom({json.dumps(prefs)})") == expected
+
+
+@pytest.mark.parametrize("total, size, page, expected", [
+    (0, 50, 0, {"page": 0, "last": 0, "start": 0, "end": 0}),
+    (120, 50, 0, {"page": 0, "last": 2, "start": 0, "end": 50}),
+    (120, 50, 2, {"page": 2, "last": 2, "start": 100, "end": 120}),
+    (100, 50, 1, {"page": 1, "last": 1, "start": 50, "end": 100}),
+    # The list shrank under the reader: the last page that exists, not an empty one.
+    (60, 50, 4, {"page": 1, "last": 1, "start": 50, "end": 60}),
+    (60, 50, -1, {"page": 0, "last": 1, "start": 0, "end": 50}),
+])
+def test_page_bounds(tmp_path, source, total, size, page, expected):
+    assert _run(tmp_path, source, f"pageBounds({total}, {size}, {page})") == expected
+
+
+def test_hub_accepts_the_key_the_client_writes():
+    key = re.search(r"^export const PAGE_SIZE_PREF = '([^']+)';",
+                    PAGER.read_text(encoding="utf-8"), re.M).group(1)
+    allowed = re.search(r"ALLOWED_PREF_KEYS = frozenset\(\[(.*?)\]\)",
+                        USERS.read_text(encoding="utf-8"), re.S).group(1)
+    assert f'"{key}"' in allowed
diff --git a/packages/meshbay-hub/tests/test_sticky_header.py b/packages/meshbay-hub/tests/test_sticky_header.py
index 32b8124..741b57f 100644
--- a/packages/meshbay-hub/tests/test_sticky_header.py
+++ b/packages/meshbay-hub/tests/test_sticky_header.py
@@ -78,6 +78,19 @@ def test_every_view_was_reached(measured):
         f"expected {EXPECTED_CASES} measurements, got {len(measured)}")
 
 
+def test_media_toolbars_were_measured_with_their_page_arrows(measured):
+    """
+    Videos and Music put previous/next arrows in the pinned toolbar once a
+    library is longer than a page (`pager.js`). The fixture sets a page smaller
+    than its library so every measurement above covers the toolbar with them;
+    this fails the fixture if that stops being true.
+    """
+    media = [c for c in measured if c["name"].split(" @")[0].endswith(("videos", "music"))]
+    assert media, "no Videos or Music case was measured"
+    bare = [c["name"] for c in media if not c.get("pager")]
+    assert not bare, "measured without page arrows: " + ", ".join(bare)
+
+
 def test_the_page_really_scrolled(measured):
     """
     Everything below compares a scrolled page with an unscrolled one. A view
diff --git a/packages/meshbay-hub/tests/test_transport_contracts.py b/packages/meshbay-hub/tests/test_transport_contracts.py
index f780073..d13cfd4 100644
--- a/packages/meshbay-hub/tests/test_transport_contracts.py
+++ b/packages/meshbay-hub/tests/test_transport_contracts.py
@@ -31,7 +31,7 @@ CREATE_GROUP = STATIC / "create-group-page.js"
 SPLIT_FILES = [APP, GROUP_PAGE, CHAT_APP, STATIC / "files-app.js",
               STATIC / "video-player.js", STATIC / "video-app.js",
               STATIC / "music-app.js", STATIC / "music-player.js",
-              STATIC / "photos-app.js",
+              STATIC / "photos-app.js", STATIC / "pager.js",
               STATIC / "group-settings.js",
               # Same reason as test_hook_ordering's STATIC_FILES: these are
               # reached through the registry, so leaving one out here means it