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.

server/server.js

@@ -515,42 +515,74 @@ app.get('/api/search', async (c) => {
 });
 
 // GET /api/channel?c=<channel>
-app.get('/api/channel', async (c) => {
-  const chan = (c.req.query('c') || '').trim();
-  if (!chan) return c.json({ ok: false, error: 'missing channel' }, 400);
+// Channel listing that works for every kind of channel, not one-off cases:
+//   1. /videos, /streams, /shorts tabs        — normal channels
+//   2. uploads playlist (UC… → UU…)           — auto-generated "- Topic" channels
+//   3. /releases, /playlists → their tracks   — artist/music channels whose only
+//      content is albums or playlists (no Videos tab, no uploads playlist)
+//   4. channel home page
+// A bare channel name is first resolved to its id with a search. A channel with
+// nothing public answers ok with no results (never a raw yt-dlp error).
+const ytdlpFlat = (url, end) => runYtdlpResilient([url, '--dump-json', '--flat-playlist', '--no-warnings', '--ignore-errors',
+  '--playlist-end', String(end)], { pooled: true });
 
-  try {
-    let out = '', results = [], lastErr = null;
-    for (const url of channelUrlCandidates(chan)) {
-      try {
-        out = await runYtdlpResilient([
-          url,
-          '--dump-json', '--flat-playlist',
-          '--no-warnings', '--ignore-errors',
-          '--playlist-end', String(CHANNEL_LIMIT),
-        ], { pooled: true });
-        results = parseCards(out);
-        if (results.length) break;
-      } catch (err) { lastErr = err; }
-    }
-    // A bare name ("Maverick City Music - Topic") is not a handle: find the
-    // channel id through a search, then try its uploads/home again.
-    if (!results.length && !/^(https?:|@|UC[\w-]{22}$)/.test(chan)) {
-      const id = await channelIdForName(chan).catch(() => null);
-      if (id) {
-        for (const url of channelUrlCandidates(id)) {
-          try {
-            out = await runYtdlpResilient([url, '--dump-json', '--flat-playlist', '--no-warnings', '--ignore-errors',
-              '--playlist-end', String(CHANNEL_LIMIT)], { pooled: true });
-            results = parseCards(out);
-            if (results.length) { lastErr = null; break; }
-          } catch (err) { lastErr = err; }
+// Playlist links (albums, playlists) in a flat tab listing.
+function playlistUrlsIn(out) {
+  const urls = [];
+  for (const line of out.split('\n')) {
+    try {
+      const j = JSON.parse(line);
+      const u = String(j.url || j.webpage_url || '');
+      if (/[?&]list=/.test(u)) urls.push(u);
+    } catch { /* not JSON */ }
+  }
+  return urls;
+}
+
+async function loadChannel(chan) {
+  let candidates = channelUrlCandidates(chan);
+  if (!/^(https?:|@|UC[\w-]{22}$)/.test(chan)) {
+    const id = await channelIdForName(chan).catch(() => null);
+    if (id) candidates = channelUrlCandidates(id);
+  }
+  const root = candidates[candidates.length - 1];
+  // 1, 2, 4 — tabs, uploads playlist, home (home is last in the candidate list)
+  const direct = [candidates[0], `${root}/streams`, `${root}/shorts`, ...candidates.slice(1)];
+  for (const url of direct) {
+    try {
+      const out = await ytdlpFlat(url, CHANNEL_LIMIT);
+      const results = parseCards(out);
+      if (results.length) return { out, results };
+    } catch { /* next source */ }
+  }
+  // 3 — albums / playlists, expanded into tracks (a few at a time).
+  for (const tab of ['releases', 'playlists']) {
+    let lists = [];
+    try { lists = playlistUrlsIn(await ytdlpFlat(`${root}/${tab}`, 15)); } catch { continue; }
+    if (!lists.length) continue;
+    const results = [], seen = new Set();
+    let out = '';
+    for (let i = 0; i < lists.length && results.length < CHANNEL_LIMIT; i += 3) {
+      const batch = await Promise.all(lists.slice(i, i + 3).map((u) => ytdlpFlat(u, 40).catch(() => '')));
+      for (const o of batch) {
+        out += o + '\n';
+        for (const card of parseCards(o)) {
+          if (seen.has(card.id)) continue;
+          seen.add(card.id);
+          results.push(card);
         }
       }
     }
-    if (!results.length && lastErr) throw lastErr;
-    // Extract channel name + URL from the first record
-    const first = results[0];
+    if (results.length) return { out, results: results.slice(0, CHANNEL_LIMIT) };
+  }
+  return { out: '', results: [] };
+}
+
+app.get('/api/channel', async (c) => {
+  const chan = (c.req.query('c') || '').trim();
+  if (!chan) return c.json({ ok: false, error: 'missing channel' }, 400);
+  try {
+    const { out, results } = await loadChannel(chan);
     let channelName = '', channelUrl = '';
     for (const line of out.split('\n')) {
       const t = line.trim();
@@ -562,9 +594,10 @@ app.get('/api/channel', async (c) => {
         if (channelName && channelUrl) break;
       } catch { /* skip */ }
     }
-    return c.json({ ok: true, channel: channelName || (first?.channel || ''), channelUrl, results });
+    return c.json({ ok: true, channel: channelName || (results[0]?.channel || ''), channelUrl, results,
+      ...(results.length ? {} : { message: 'This channel has no public videos to show.' }) });
   } catch (err) {
-    return c.json({ ok: false, error: err.message }, 500);
+    return c.json({ ok: false, error: 'Could not load this channel right now — try again.' }, 500);
   }
 });