fix(playlists): fall back to playlistHeaderRenderer when sidebar is absent

YouTube stopped returning sidebar.playlistSidebarRenderer for many
playlists; extract the same fields from header.playlistHeaderRenderer
instead to prevent 500 errors on /playlist pages.

Also fix the -1 video count on lockupViewModel playlist cards: make
badge text matching case-insensitive and add a numeric-prefix fallback
so counts are recovered even when YouTube changes the badge wording.

src/invidious/playlists.cr

@@ -345,8 +345,35 @@ def fetch_playlist(plid : String)
   initial_data = YoutubeAPI.browse("VL" + plid, params: "")
 
   playlist_sidebar_renderer = initial_data.dig?("sidebar", "playlistSidebarRenderer", "items")
-  raise InfoException.new("Could not extract playlistSidebarRenderer.") if !playlist_sidebar_renderer
+  header_renderer = initial_data.dig?("header", "playlistHeaderRenderer")
 
+  raise InfoException.new("Could not extract playlist data.") if playlist_sidebar_renderer.nil? && header_renderer.nil?
+
+  views = 0_i64
+  updated = Time.utc
+  video_count = 0
+  subtitle = extract_text(header_renderer.try &.["subtitle"]?)
+
+  # stats parsing is the same format in both sidebar and header renderers
+  stats_source = playlist_sidebar_renderer.try(&.dig?(0, "playlistSidebarPrimaryInfoRenderer", "stats")) ||
+                 header_renderer.try(&.["stats"]?)
+
+  stats_source.try &.as_a.each do |stat|
+    text = stat["runs"]?.try &.as_a.map(&.["text"].as_s).join("") || stat["simpleText"]?.try &.as_s
+    next if !text
+
+    if text.includes? "video"
+      video_count = text.gsub(/\D/, "").to_i? || 0
+    elsif text.includes? "episode"
+      video_count = text.gsub(/\D/, "").to_i? || 0
+    elsif text.includes? "view"
+      views = text.gsub(/\D/, "").to_i64? || 0_i64
+    elsif !text.includes? "Pay to watch"
+      updated = decode_date(text.lchop("Last updated on ").lchop("Updated "))
+    end
+  end
+
+  if playlist_sidebar_renderer
     playlist_info = playlist_sidebar_renderer.dig?(0, "playlistSidebarPrimaryInfoRenderer")
     raise InfoException.new("Could not extract playlist info") if !playlist_info
 
@@ -368,27 +395,6 @@ def fetch_playlist(plid : String)
       "thumbnail", "thumbnails", 0, "url"
     ).try &.as_s
 
-  views = 0_i64
-  updated = Time.utc
-  video_count = 0
-
-  subtitle = extract_text(initial_data.dig?("header", "playlistHeaderRenderer", "subtitle"))
-
-  playlist_info["stats"]?.try &.as_a.each do |stat|
-    text = stat["runs"]?.try &.as_a.map(&.["text"].as_s).join("") || stat["simpleText"]?.try &.as_s
-    next if !text
-
-    if text.includes? "video"
-      video_count = text.gsub(/\D/, "").to_i? || 0
-    elsif text.includes? "episode"
-      video_count = text.gsub(/\D/, "").to_i? || 0
-    elsif text.includes? "view"
-      views = text.gsub(/\D/, "").to_i64? || 0_i64
-    elsif !text.includes? "Pay to watch"
-      updated = decode_date(text.lchop("Last updated on ").lchop("Updated "))
-    end
-  end
-
     if playlist_sidebar_renderer.size < 2
       author = ""
       author_thumbnail = ""
@@ -404,6 +410,27 @@ def fetch_playlist(plid : String)
       author_thumbnail = author_info.dig?("thumbnail", "thumbnails", 0, "url").try &.as_s || ""
       ucid = author_info.dig?("title", "runs", 0, "navigationEndpoint", "browseEndpoint", "browseId").try &.as_s || ""
     end
+  else
+    # Sidebar gone — fall back to playlistHeaderRenderer (YouTube changed response format)
+    hr = header_renderer.not_nil!
+
+    title = extract_text(hr["title"]?) || ""
+
+    desc_item = hr["descriptionText"]? || hr["description"]?
+    description_txt = desc_item.try &.["runs"]?.try &.as_a
+      .map(&.["text"].as_s).join("") || desc_item.try &.["simpleText"]?.try &.as_s || ""
+    description_html = desc_item.try &.["runs"]?.try &.as_a
+      .try { |run| content_to_comment_html(run).try &.to_s } || "<p></p>"
+
+    thumbnail = hr.dig?("thumbnail", "thumbnails", 0, "url").try &.as_s
+
+    owner_run = hr.dig?("ownerText", "runs", 0)
+    author = owner_run.try &.["text"]?.try &.as_s || ""
+    ucid = owner_run.try &.dig?("navigationEndpoint", "browseEndpoint", "browseId").try &.as_s || ""
+    author_thumbnail = hr.dig?("channelAvatar", "decoratedAvatarViewModel", "avatar",
+      "avatarViewModel", "image", "sources", 0, "url").try &.as_s ||
+      hr.dig?("avatar", "thumbnails", 0, "url").try &.as_s || ""
+  end
 
   return Playlist.new({
     title:            title,

src/invidious/yt_backend/extractors.cr

@@ -675,13 +675,20 @@ private module Parsers
       #
       # NOTE: this simplistic `.to_i` conversion might not work on larger
       # playlists and hasn't been tested.
-      video_count = thumbnail_view_model.dig("overlays").as_a
+      all_badge_texts = thumbnail_view_model.dig("overlays").as_a
         .compact_map(&.dig?("thumbnailOverlayBadgeViewModel", "thumbnailBadges").try &.as_a)
         .flatten
-        .find(nil, &.dig?("thumbnailBadgeViewModel", "text").try { |node|
-          {"episodes", "videos"}.any? { |str| node.as_s.ends_with?(str) }
-        })
-        .try &.dig("thumbnailBadgeViewModel", "text").as_s.to_i(strict: false)
+        .compact_map(&.dig?("thumbnailBadgeViewModel", "text").try &.as_s)
+
+      # Prefer badges explicitly labeled "videos" or "episodes" (case-insensitive)
+      video_count = all_badge_texts
+        .find { |t| {"episodes", "videos"}.any? { |s| t.downcase.ends_with?(s) } }
+        .try &.to_i(strict: false)
+
+      # Fallback: any badge whose text starts with a digit
+      video_count ||= all_badge_texts
+        .find { |t| t[0]?.try &.ascii_number? }
+        .try &.to_i(strict: false)
 
       metadata = item_contents.dig("metadata", "lockupMetadataViewModel")
       title = metadata.dig("title", "content").as_s