Channels load for every channel type; parallel saves setting (default 4)

Channels: one loader tries, in order, the Videos/Live/Shorts tabs (normal
channels), the uploads playlist (Topic channels), the Releases/Playlists tabs
expanded into their tracks (artist/music channels whose only content is albums,
e.g. Cathedral of Praise Worship), then the home page; bare names are resolved
to an id first. Nothing public → ok with a message, never a raw yt-dlp error.

Saves: SaveSlots caps concurrent offline saves (Settings → Offline cache →
Videos saved at once, 1–8, default 4); queued saves show "Waiting for a free
slot", and resumed saves now run up to the limit instead of one at a time.

frontend/app.js

@@ -270,6 +270,21 @@ const SearchLibrary = (() => {
 // OPFS bridge wrappers — return the same shape as the Tauri cache_* commands
 // so the rest of app.js works without changes.
 
+// ---------- Save slots: how many videos save at once (Settings, default 4) ----------
+const SaveSlots = (() => {
+  let active = 0;
+  const waiters = [];
+  const limit = () => Math.max(1, Math.min(8, Number(data.settings.parallelSaves) || 4));
+  function pump() {
+    while (waiters.length && active < limit()) { active++; waiters.shift()(); }
+  }
+  return {
+    acquire() { return new Promise((r) => { waiters.push(r); pump(); }); },
+    release() { active = Math.max(0, active - 1); pump(); },
+    pump,
+  };
+})();
+
 // ---------- Save queue: resumable saves survive reloads and dropped links ----------
 // Every save is recorded here when it starts and removed when it finishes or
 // fails for good. A save that only paused (partial kept on the device) stays
@@ -298,6 +313,7 @@ const SaveQueue = (() => {
 
   function label(p) {
     if (!p) return '⏳ Saving for offline…';
+    if (p.phase === 'waiting') return '⏳ Waiting for a free slot…';
     const mb = (n) => (n / 1048576).toFixed(n >= 1048576 * 100 ? 0 : 1);
     if (p.phase === 'preparing') return `⏳ Preparing on server… ${Math.round((p.elapsed || 0) / 1000)} s`;
     if (p.phase === 'verifying') return '✓ Verifying…';
@@ -325,13 +341,14 @@ const SaveQueue = (() => {
     if (running || !navigator.onLine) return;
     running = true;
     try {
+      const jobs = [];
       for (const v of pending()) {
         if (cachedIds.has(v.id)) { remove(v.id); continue; }
         if (downloading.has(v.id)) continue;
         if (Date.now() - v.at > MAX_AGE) { cancel(v.id); continue; }
-        await preload(v, { quiet: true }); // one at a time: the homelab link is the bottleneck
-        if (!navigator.onLine) break;
+        jobs.push(preload(v, { quiet: true })); // SaveSlots caps how many run at once
       }
+      await Promise.all(jobs);
     } finally { running = false; }
     if (view.type === 'downloads') renderList();
   }
@@ -594,6 +611,7 @@ const DEFAULT_SETTINGS = {
   shuffle: false,           // shuffle upcoming tracks when playing a list
   theme: 'dark',            // 'dark' | 'light' | 'contrast'
   fontScale: 'normal',      // 'small' | 'normal' | 'large' | 'xl'
+  parallelSaves: 4,         // offline saves running at once (Settings → Offline cache)
   density: 'comfortable',   // 'comfortable' | 'compact'
   perfMode: false,          // disable heavy visual effects for speed
   reduceMotion: false,      // disable animations
@@ -1751,7 +1769,12 @@ async function preload(video, { quiet = false, mux = false } = {}) {
   if (current && current.meta && current.meta.id === id) updateNowPlayingActions();
   if (!quiet) toast(`Saving “${video.title}” for offline…`);
   SaveQueue.add(video);
+  SaveQueue.progress(id, { phase: 'waiting' });
+  let slot = false;
   try {
+    await SaveSlots.acquire();
+    slot = true;
+    SaveQueue.progress(id, null);
     const res = await API.cacheDownload(id, { mux, onProgress: (p) => SaveQueue.progress(id, p) });
     if (res && res.paused) {
       // The partial stays on the device; SaveQueue picks it up again.
@@ -1772,6 +1795,7 @@ async function preload(video, { quiet = false, mux = false } = {}) {
     SaveQueue.remove(id);
     if (!quiet) toast('⚠ Saving not supported in this build.');
   } finally {
+    if (slot) SaveSlots.release();
     SaveQueue.progress(id, null);
     downloading.delete(id);
     downloadMeta.delete(id);
@@ -8937,6 +8961,13 @@ async function renderSettings() {
         </span>
         <input id="setAutoPreload" type="checkbox" ${data.settings.autoPreload ? 'checked' : ''} />
       </label>
+      <label class="set-row">
+        <span>
+          Videos saved at once
+          <small>How many offline saves run in parallel; the rest wait their turn.</small>
+        </span>
+        ${sel('setParallelSaves', String(Math.max(1, Math.min(8, Number(data.settings.parallelSaves) || 4))), [['1', '1'], ['2', '2'], ['3', '3'], ['4', '4 (default)'], ['6', '6'], ['8', '8']])}
+      </label>
       <div class="set-row">
         <span>Storage used</span>
         <span id="cacheTotal" class="set-stat">…</span>
@@ -9084,6 +9115,7 @@ async function renderSettings() {
   $('setTheme').addEventListener('change', (e) => { data.settings.theme = e.target.value; applyAppearance(); persist(); });
   $('setLayout').addEventListener('change', (e) => { data.settings.layout = e.target.value; applyAppearance(); persist(); });
   $('setFont').addEventListener('change', (e) => { data.settings.fontScale = e.target.value; applyAppearance(); persist(); });
+  $('setParallelSaves').addEventListener('change', (e) => { data.settings.parallelSaves = Number(e.target.value) || 4; persist(); SaveSlots.pump(); });
   $('setDensity').addEventListener('change', (e) => { data.settings.density = e.target.value; applyAppearance(); persist(); });
   $('setPerf').addEventListener('change', (e) => { data.settings.perfMode = e.target.checked; applyAppearance(); persist(); });
   $('setMotion').addEventListener('change', (e) => { data.settings.reduceMotion = e.target.checked; applyAppearance(); persist(); });