fix: clean Deno scraper output

Remove source-site navigation and controls that leaked into generated API and runtime pages, while preserving the source language metadata DevDocs uses for syntax highlighting. Add representative regression fixtures for the reviewer-reported page shapes.

Test Plan:
- Ran the focused Deno suite: 17 runs, 73 assertions, 0 failures.
- Ran the remaining Ruby suite excluding two independently failing Windows-only baseline files: 665 runs, 927 assertions, 0 failures.
- Compared old and new filters on current Network and @std/fmt source pages; all measured chrome counts dropped to zero while TypeScript, JavaScript, and shell language metadata was preserved.
- Ran Ruby syntax checks and git diff --check.

Author: srpatcha

lib/docs/filters/deno/clean_html.rb

@@ -2,17 +2,24 @@ module Docs
   class Deno
     class CleanHtmlFilter < Filter
       def call
-        @doc = at_css('main, article, [role="main"], .markdown-body') || doc
+        @doc = at_css('main#content article', 'article') || doc
 
-        css('nav, footer, .sidebar, .breadcrumb, .toc,
-             .page-nav, .edit-link, .header-anchor, script, style').remove
+        css('.breadcrumbs', '.copy-page-split', '.copyButton',
+            '.docNodeKindIcon', '.header-anchor', 'a > svg',
+            'nav[aria-label="Breadcrumb"]',
+            'nav[aria-label="Previous and next page"]').remove
+
+        css('details > summary').each do |node|
+          node.parent.remove if node.content.strip == 'On this page'
+        end
+
+        css('h1, h2, h3, h4, h5, h6').each do |node|
+          node.css('a.anchor[aria-label="Anchor"]').remove
+        end
 
         css('pre > code').each do |node|
-          if node['class']
-            lang = node['class'][/language-(\w+)/, 1]
-            node.parent['data-language'] = lang if lang
-          end
-          node.parent['data-language'] ||= 'typescript'
+          language = node['class'].to_s[/\blanguage-([\w-]+)/, 1]
+          node.parent['data-language'] = language if language
         end
 
         doc

test/files/deno_api.html

@@ -0,0 +1,29 @@
+<!doctype html>
+<html>
+  <body>
+    <nav>Site navigation</nav>
+    <main id="content">
+      <div class="w-full">
+        <article>
+          <div class="markdown-body">
+            <ul class="breadcrumbs"><li>Deno</li><li>Network</li></ul>
+            <div class="multiSymbolPage">
+              <h1>Network</h1>
+              <p>Networking APIs.</p>
+              <div class="namespaceItem">
+                <div class="docNodeKindIcon"><div title="Function">f</div></div>
+                <a href="#Deno.connect">Deno.connect</a>
+              </div>
+              <div class="relative">
+                <pre><code class="highlight language-ts">await Deno.connect();</code></pre>
+                <button class="copyButton" title="Copy">Copy</button>
+              </div>
+            </div>
+          </div>
+        </article>
+        <section id="feedback-section">Did you find what you needed?</section>
+      </div>
+    </main>
+    <footer>Site footer</footer>
+  </body>
+</html>

test/files/deno_runtime.html

@@ -0,0 +1,36 @@
+<!doctype html>
+<html>
+  <body>
+    <main id="content">
+      <div class="w-full">
+        <article>
+          <details><summary>On this page</summary><a href="#overview">Overview</a></details>
+          <div class="markdown-body">
+            <header>
+              <nav aria-label="Breadcrumb">Reference / Standard library</nav>
+              <div class="copy-page-split"><button>Copy page</button></div>
+            </header>
+            <h1>@std/fmt</h1>
+            <h2 id="overview"><a class="anchor" aria-label="Anchor" href="#overview">#</a>Overview</h2>
+            <p>Provides utilities for formatting text.</p>
+            <div class="relative">
+              <pre><code class="highlight language-js">console.log('formatted');</code></pre>
+              <button class="copyButton" title="Copy">Copy</button>
+            </div>
+            <h2>Runtime compatibility</h2>
+            <p>Works with Deno.</p>
+            <h2>Add to your project</h2>
+            <pre><code class="highlight language-sh">deno add jsr:@std/fmt</code></pre>
+            <pre><code class="highlight language-jsonc">{"imports": {}}</code></pre>
+            <a href="https://jsr.io/@std/fmt/doc">See all symbols</a>
+          </div>
+          <nav aria-label="Previous and next page">Previous Next</nav>
+        </article>
+        <section id="feedback-section">
+          <h2>Did you find what you needed?</h2>
+          <a href="https://github.com/denoland/docs">Edit this page</a>
+        </section>
+      </div>
+    </main>
+  </body>
+</html>

test/lib/docs/scrapers/deno_test.rb

@@ -1,4 +1,5 @@
-require_relative '../../test_helper'
+require_relative '../../../test_helper'
+require_relative '../../../../lib/docs'
 
 class DenoScraperTest < Minitest::Test
   def setup
@@ -82,3 +83,74 @@ def test_inherits_from_url_scraper
     assert @scraper_class < Docs::UrlScraper
   end
 end
+
+class DenoEntriesFilterTest < Minitest::Test
+  def test_extracts_api_entry_from_content_heading
+    entry = filter_fixture('deno_api.html', 'api/deno/network/').first
+
+    assert_equal 'Network', entry.name
+    assert_equal 'API', entry.type
+  end
+
+  def test_extracts_runtime_entry_from_content_heading
+    entry = filter_fixture('deno_runtime.html', 'runtime/reference/std/fmt/').first
+
+    assert_equal '@std/fmt', entry.name
+    assert_equal 'Runtime', entry.type
+  end
+
+  private
+
+  def filter_fixture(name, path)
+    html = File.read(File.join(DenoCleanHtmlFilterTest::FIXTURES_PATH, name))
+    doc = Docs::Parser.new(html).html
+    context = {
+      base_url: Docs::URL.parse('https://docs.deno.com/'),
+      url: Docs::URL.parse("https://docs.deno.com/#{path}"),
+      root_path: 'api/',
+    }
+    result = { path: path }
+    content = Docs::Deno::CleanHtmlFilter.new(doc, context, result).call
+    Docs::Deno::EntriesFilter.new(content, context, result).call
+    result[:entries]
+  end
+end
+
+class DenoCleanHtmlFilterTest < Minitest::Test
+  FIXTURES_PATH = File.expand_path('../../../files', __dir__)
+
+  def test_cleans_api_page_chrome_and_preserves_content
+    output = filter_fixture('deno_api.html')
+
+    assert_equal 'article', output.name
+    assert_equal 'Network', output.at_css('h1').content
+    assert_includes output.text, 'Deno.connect'
+    refute_includes output.text, 'Site navigation'
+    refute_includes output.text, 'Did you find what you needed?'
+    assert_empty output.css('.breadcrumbs, .docNodeKindIcon, .copyButton')
+    assert_equal 'ts', output.at_css('pre')['data-language']
+  end
+
+  def test_cleans_runtime_page_chrome_and_preserves_content
+    output = filter_fixture('deno_runtime.html')
+
+    assert_equal '@std/fmt', output.at_css('h1').content
+    assert_includes output.text, 'Runtime compatibility'
+    assert_includes output.text, 'Add to your project'
+    assert_includes output.text, 'See all symbols'
+    refute_includes output.text, 'On this page'
+    refute_includes output.text, 'Copy page'
+    refute_includes output.text, 'Did you find what you needed?'
+    refute_includes output.text, 'Edit this page'
+    assert_empty output.css('.copyButton, a.anchor, nav')
+    assert_equal %w(js sh jsonc), output.css('pre').map { |node| node['data-language'] }
+  end
+
+  private
+
+  def filter_fixture(name)
+    html = File.read(File.join(FIXTURES_PATH, name))
+    doc = Docs::Parser.new(html).html
+    Docs::Deno::CleanHtmlFilter.new(doc, {}, {}).call
+  end
+end