视频标题的显示发生了变化。

spec/invidious/frontend/watch_page_spec.cr

@@ -0,0 +1,56 @@
+require "../../spec_helper"
+require "../../../src/invidious/frontend/watch_page"
+
+Spectator.describe Invidious::Frontend::WatchPage do
+  describe ".linkify_title_hashtags" do
+    it "links hashtags while preserving surrounding punctuation" do
+      result = Invidious::Frontend::WatchPage.linkify_title_hashtags(
+        "Watch (#music), then #news!"
+      )
+
+      expect(result).to eq(
+        %(Watch (<a href="/hashtag/music">#music</a>), then <a href="/hashtag/news">#news</a>!)
+      )
+    end
+
+    it "does not link hashes inside words or without a name" do
+      result = Invidious::Frontend::WatchPage.linkify_title_hashtags(
+        "C# test#music #"
+      )
+
+      expect(result).to eq("C# test#music #")
+    end
+
+    it "links and encodes Unicode hashtags" do
+      hashtag = "\u{97F3}\u{4E50}"
+
+      result = Invidious::Frontend::WatchPage.linkify_title_hashtags(
+        "Listen ##{hashtag}"
+      )
+
+      expect(result).to eq(
+        %(Listen <a href="/hashtag/%E9%9F%B3%E4%B9%90">##{hashtag}</a>)
+      )
+    end
+
+    it "escapes title markup and link text" do
+      result = Invidious::Frontend::WatchPage.linkify_title_hashtags(
+        %(<script>#music</script> & #news)
+      )
+
+      expect(result).to eq(
+        %(&lt;script&gt;<a href="/hashtag/music">#music</a>&lt;/script&gt; &amp; <a href="/hashtag/news">#news</a>)
+      )
+    end
+
+    it "does not turn character-reference-like text into hashtag links" do
+      result = Invidious::Frontend::WatchPage.linkify_title_hashtags(
+        "Literal &#65; and &#x41; plus #music"
+      )
+
+      expect(result).to eq(
+        %(Literal &amp;#65; and &amp;#x41; plus <a href="/hashtag/music">#music</a>)
+      )
+    end
+  end
+end

src/invidious/frontend/watch_page.cr

@@ -1,6 +1,47 @@
 module Invidious::Frontend::WatchPage
   extend self
 
+  def linkify_title_hashtags(title : String) : String
+    characters = title.chars
+
+    String.build(title.bytesize) do |html|
+      index = 0
+
+      while index < characters.size
+        character = characters[index]
+        starts_hashtag = character == '#' &&
+                         (index == 0 || !hashtag_prefix_character?(characters[index - 1]))
+
+        if starts_hashtag
+          hashtag_end = index + 1
+          while hashtag_end < characters.size && hashtag_character?(characters[hashtag_end])
+            hashtag_end += 1
+          end
+
+          if hashtag_end > index + 1
+            hashtag = characters[index + 1...hashtag_end].join
+
+            html << %(<a href="/hashtag/) << URI.encode_path(hashtag) << %(">#)
+            html << HTML.escape(hashtag) << "</a>"
+            index = hashtag_end
+            next
+          end
+        end
+
+        html << HTML.escape(character.to_s)
+        index += 1
+      end
+    end
+  end
+
+  private def hashtag_character?(character : Char) : Bool
+    character.alphanumeric? || character == '_'
+  end
+
+  private def hashtag_prefix_character?(character : Char) : Bool
+    hashtag_character?(character) || character == '&'
+  end
+
   # A handy structure to pass many elements at
   # once to the download widget function
   struct VideoAssets

src/invidious/views/watch.ecr

@@ -93,7 +93,7 @@ we're going to need to do it here in order to allow for translations.
 
 <div class="h-box">
     <h1>
-        <%= title %>
+        <%= Invidious::Frontend::WatchPage.linkify_title_hashtags(video.title) %>
         <% if params.listen %>
             <a title="<%=I18n.translate(locale, "Video mode")%>" id="link-iv-listen" data-base-url="/watch?<%= env.params.query %>&listen=0" href="/watch?<%= env.params.query %>&listen=0">
                 <i class="icon ion-ios-videocam"></i>