Per-channel "skip auth check" toggle for the youtubetab warning

yt-dlp prints a scary-looking ERROR when it can't confirm a channel
tab loaded authenticated:

  ERROR: [youtube:tab] @Channel: Playlists that require authentication
  may not extract correctly without a successful webpage download…
  pass "--extractor-args youtubetab:skip=authcheck" to skip this check

For PUBLIC channels that's just noise — there's no auth-gated content
to miss, and the flag silences it without changing which videos are
found. But for members-only/private channels archived with cookies,
the warning is a real "your cookies may not be working, you might be
getting an incomplete list" signal worth keeping.

So make it a per-channel toggle rather than a blanket setting:

- DownloadOptions gains `skip_auth_check: bool`; apply() emits
  `--extractor-args youtubetab:skip=authcheck` when set. (Its own flag;
  the youtubetab: namespace is distinct from the POT provider's
  youtubepot-bgutilhttp: one, so they coexist.)
- Desktop + web channel-options dialogs gain a checkbox with a tooltip
  spelling out the public-vs-private trade-off.

1 new test; 81 pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/app.rs

@@ -219,6 +219,7 @@ struct ChannelOptionsForm {
     quality_idx: usize,           // 0=default, 1=Best, 2=1080p, 3=720p, 4=480p, 5=360p
     audio_only: bool,
     fetch_comments: bool,
+    skip_auth_check: bool,
     limit_rate_kb: String,
     min_filesize_mb: String,
     max_filesize_mb: String,
@@ -440,6 +441,7 @@ impl App {
             quality_idx,
             audio_only: opts.audio_only,
             fetch_comments: opts.fetch_comments,
+            skip_auth_check: opts.skip_auth_check,
             limit_rate_kb: num(opts.limit_rate_kb),
             min_filesize_mb: num(opts.min_filesize_mb),
             max_filesize_mb: num(opts.max_filesize_mb),
@@ -470,6 +472,7 @@ impl App {
             quality,
             audio_only: f.audio_only,
             fetch_comments: f.fetch_comments,
+            skip_auth_check: f.skip_auth_check,
             limit_rate_kb: parse_num(&f.limit_rate_kb),
             min_filesize_mb: parse_num(&f.min_filesize_mb),
             max_filesize_mb: parse_num(&f.max_filesize_mb),
@@ -1904,6 +1907,11 @@ impl App {
                         .on_hover_text("Slow on popular videos. Once captured, comments are browsable from the player modal in the web UI.");
                     ui.end_row();
 
+                    ui.label("Skip auth check");
+                    ui.checkbox(&mut form.skip_auth_check, "Suppress the channel-tab authentication warning")
+                        .on_hover_text("Passes --extractor-args youtubetab:skip=authcheck. Safe for PUBLIC channels — it silences yt-dlp's \"playlists that require authentication may not extract correctly\" warning without changing which videos are found. Leave OFF for members-only/private channels, where that warning signals your cookies may not be working.");
+                    ui.end_row();
+
                     ui.label("Bandwidth cap (KB/s)");
                     ui.add(egui::TextEdit::singleline(&mut form.limit_rate_kb).desired_width(100.0).hint_text("off"));
                     ui.end_row();

src/download_options.rs

@@ -79,6 +79,19 @@ pub struct DownloadOptions {
     /// When on, the web UI's player modal exposes a Comments tab.
     #[serde(default)]
     pub fetch_comments: bool,
+
+    /// Skip yt-dlp's channel-tab authentication sanity check by passing
+    /// `--extractor-args youtubetab:skip=authcheck`.
+    ///
+    /// yt-dlp warns ("Playlists that require authentication may not
+    /// extract correctly…") when it can't confirm a channel page loaded
+    /// authenticated. For PUBLIC channels that warning is noise — there's
+    /// no auth-gated content to miss — so this silences it. Leave OFF for
+    /// channels where you archive members-only / private content with
+    /// cookies: there the warning is a real "your cookies aren't working,
+    /// you may be getting an incomplete list" signal worth keeping.
+    #[serde(default)]
+    pub skip_auth_check: bool,
 }
 
 impl DownloadOptions {
@@ -129,6 +142,12 @@ impl DownloadOptions {
         if self.fetch_comments {
             cmd.arg("--write-comments");
         }
+        if self.skip_auth_check {
+            // Its own --extractor-args flag; the youtubetab: namespace is
+            // distinct from the POT provider's youtubepot-bgutilhttp: one,
+            // so they coexist as separate flags without clobbering.
+            cmd.arg("--extractor-args").arg("youtubetab:skip=authcheck");
+        }
     }
 
     /// Deserialize from the JSON blob stored in `channel_options.options_json`.
@@ -182,6 +201,14 @@ mod tests {
         assert_eq!(args, vec!["--sub-langs", "en,ja,es"]);
     }
 
+    #[test]
+    fn skip_auth_check_emits_extractor_arg() {
+        let mut cmd = Command::new("yt-dlp");
+        DownloadOptions { skip_auth_check: true, ..Default::default() }.apply(&mut cmd);
+        let args: Vec<String> = cmd.get_args().map(|a| a.to_string_lossy().into_owned()).collect();
+        assert_eq!(args, vec!["--extractor-args", "youtubetab:skip=authcheck"]);
+    }
+
     #[test]
     fn audio_only_adds_extract_audio_chain() {
         let mut cmd = Command::new("yt-dlp");

src/web_ui/index.html

@@ -913,6 +913,9 @@ async function openChannelOptions(idx){
     <div class="settings-row"><label>Fetch comments</label>
       <input type="checkbox" id="opt-comments" ${opts.fetch_comments?'checked':''}></div>
     <div class="settings-hint" style="margin-bottom:4px">Adds <code>--write-comments</code>. Embeds the comment tree into info.json — slow for popular videos but enables the Comments tab in the player.</div>
+    <div class="settings-row"><label>Skip auth check</label>
+      <input type="checkbox" id="opt-skipauth" ${opts.skip_auth_check?'checked':''}></div>
+    <div class="settings-hint" style="margin-bottom:4px">Adds <code>--extractor-args youtubetab:skip=authcheck</code>. Safe for <strong>public</strong> channels — silences the "playlists that require authentication may not extract correctly" warning without changing which videos are found. Leave off for members-only/private channels, where that warning means your cookies may not be working.</div>
     <div class="settings-row"><label>Bandwidth cap (KB/s)</label>
       <input type="number" id="opt-rate" value="${opts.limit_rate_kb||''}" placeholder="off" min="0" style="width:90px;background:var(--bg);color:var(--text);border:1px solid var(--border);border-radius:4px;padding:4px 6px"></div>
     <div class="settings-row"><label>Min size (MB)</label>
@@ -949,6 +952,7 @@ function readChannelOptionsForm(){
     quality:q?q:null,
     audio_only:document.getElementById('opt-audio')?.checked||false,
     fetch_comments:document.getElementById('opt-comments')?.checked||false,
+    skip_auth_check:document.getElementById('opt-skipauth')?.checked||false,
     limit_rate_kb:intOrNull('opt-rate'),
     min_filesize_mb:intOrNull('opt-minsz'),
     max_filesize_mb:intOrNull('opt-maxsz'),