Try alternate YouTube clients for unavailable save sources

server/ytdlp-resilience.js

@@ -0,0 +1,39 @@
+// Bounded client fallbacks shared by metadata probes and actual downloads.
+export const BOT_CHECK_RE = /Sign in to confirm|not a bot|confirm you.{0,3}re not a bot/i;
+export const DEFAULT_FALLBACK_CLIENTS = ['web_embedded', 'web_safari', 'tv_simply', 'android_vr', 'mweb'];
+
+export function canTryAnotherClient(error) {
+  const message = String(error?.message || error || '');
+  // Explicit access restrictions are not fixed by selecting a different client.
+  if (/private video|members.only|join this channel|not available in your country|geo.?restricted|removed by|video has been removed|copyright claim|age.restricted|confirm your age/i.test(message)) return false;
+  return BOT_CHECK_RE.test(message) || /video unavailable|requested format (?:is )?not available|no video formats found/i.test(message);
+}
+
+export function createResilientYtdlp({ run, withCookies = args => args, clients = DEFAULT_FALLBACK_CLIENTS, log = console }) {
+  return async function runResilient(args, opts = {}) {
+    const explicitClient = args.some(arg => String(arg).includes('player_client=') || String(arg).includes('player-client='));
+    if (opts.signal?.aborted) throw opts.signal.reason || new Error('save cancelled');
+    try {
+      return await run(withCookies(args), opts);
+    } catch (initial) {
+      if (explicitClient || opts.signal?.aborted || !canTryAnotherClient(initial)) throw initial;
+      const failures = [{ client: 'default', error: initial }];
+      for (const client of [...new Set(clients)]) {
+        if (opts.signal?.aborted) throw opts.signal.reason || initial;
+        try {
+          const out = await run(withCookies(['--extractor-args', `youtube:player_client=${client}`, ...args]), opts);
+          log.warn?.(`[ytplayer] YouTube fallback succeeded via player_client=${client}`);
+          return out;
+        } catch (error) {
+          failures.push({ client, error });
+          if (opts.signal?.aborted || !canTryAnotherClient(error)) throw error;
+        }
+      }
+      // Keep the original useful diagnosis, not the final client's weaker
+      // "no formats" error. Retain the bounded attempt trail for diagnostics.
+      const error = new Error(`${initial.message}\nYouTube clients tried: ${failures.map(f => f.client).join(', ')}`, { cause: initial });
+      error.attempts = failures.map(({ client, error }) => ({ client, detail: String(error.message || error) }));
+      throw error;
+    }
+  };
+}