dart-lang
diff --git a/‎lib/src/generator/generator_backend.dart
+3-9 b/‎lib/src/generator/generator_backend.dart
+3-9
diff --git a/‎lib/src/generator/templates.aot_renderers_for_html.dart
+34 b/‎lib/src/generator/templates.aot_renderers_for_html.dart
+34
diff --git a/‎lib/src/generator/templates.dart
+12 b/‎lib/src/generator/templates.dart
+12
@@ -116,20 +116,14 @@ abstract class GeneratorBackend {
     writer.write(_pathContext.join('index.json'), '$json\n');
   }
 
-  String _redirectContent(Category category) => '''<!DOCTYPE html>
-<html>
-    <head>
-        <meta http-equiv="refresh" content="0; url=${category.fileName}" />
-    </head>
-</html> ''';
-
   /// Emits documentation content for the [category].
   void generateCategory(PackageGraph packageGraph, Category category) {
     var data = CategoryTemplateData(options, packageGraph, category);
     var content = templates.renderCategory(data);
     write(writer, category.filePath, data, content);
-    if (category.filePath != category.legacyFilePath) {
-      writer.write(category.legacyFilePath, _redirectContent(category));
+    if (category.filePath != category.redirectFilePath) {
+      var redirectContent = templates.renderCategoryRedirect(data);
+      write(writer, category.redirectFilePath, data, redirectContent);
     }
 
     runtimeStats.incrementAccumulator('writtenCategoryFileCount');
 
@@ -234,6 +234,40 @@ String renderCategory(CategoryTemplateData context0) {
   return buffer.toString();
 }
 
+String renderCategoryRedirect(CategoryTemplateData context0) {
+  final buffer = StringBuffer();
+  buffer.write('''<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <link rel="canonical" href="''');
+  if (context0.useBaseHref) {
+    var context1 = context0.htmlBase;
+    buffer.write(context0.htmlBase);
+  }
+  buffer.writeEscaped(context0.self.href);
+  buffer.write('''" />
+    <meta http-equiv="refresh" content="0; url=''');
+  if (context0.useBaseHref) {
+    var context2 = context0.htmlBase;
+    buffer.write(context0.htmlBase);
+  }
+  buffer.writeEscaped(context0.self.href);
+  buffer.write('''" />
+  </head>
+  <body>
+    <p><a href="''');
+  if (context0.useBaseHref) {
+    var context3 = context0.htmlBase;
+    buffer.write(context0.htmlBase);
+  }
+  buffer.writeEscaped(context0.self.href);
+  buffer.write('''">New URL</a></p>
+  </body>
+</html>''');
+
+  return buffer.toString();
+}
+
 String renderClass(ClassTemplateData context0) {
   final buffer = StringBuffer();
   buffer.write(_renderClass_partial_head_0(context0));
 
@@ -12,6 +12,9 @@
 
 @Renderer(#renderCategory, Context<CategoryTemplateData>(), 'category',
     visibleTypes: _visibleTypes)
+@Renderer(#renderCategoryRedirect, Context<CategoryTemplateData>(),
+    'category_redirect',
+    visibleTypes: _visibleTypes)
 @Renderer(#renderClass, Context<ClassTemplateData>(), 'class')
 @Renderer(#renderConstructor, Context<ConstructorTemplateData>(), 'constructor')
 @Renderer(#renderEnum, Context<EnumTemplateData>(), 'enum')
@@ -92,6 +95,7 @@ const _visibleTypes = {
 /// The collection of [Template] objects.
 abstract class Templates {
   String renderCategory(CategoryTemplateData context);
+  String renderCategoryRedirect(CategoryTemplateData context);
   String renderClass<T extends Class>(ClassTemplateData context);
   String renderConstructor(ConstructorTemplateData context);
   String renderEnum(EnumTemplateData context);
@@ -141,6 +145,10 @@ class HtmlAotTemplates implements Templates {
   String renderCategory(CategoryTemplateData context) =>
       aot_renderers_for_html.renderCategory(context);
 
+  @override
+  String renderCategoryRedirect(CategoryTemplateData context) =>
+      aot_renderers_for_html.renderCategoryRedirect(context);
+
   @override
   String renderClass<T extends Class>(ClassTemplateData context) =>
       aot_renderers_for_html.renderClass(context);
@@ -222,6 +230,10 @@ class RuntimeTemplates implements Templates {
   String renderCategory(CategoryTemplateData context) =>
       runtime_renderers.renderCategory(context, _categoryTemplate);
 
+  @override
+  String renderCategoryRedirect(CategoryTemplateData context) =>
+      runtime_renderers.renderCategoryRedirect(context, _categoryTemplate);
+
   @override
   String renderClass<T extends Class>(ClassTemplateData context) =>
       runtime_renderers.renderClass(context, _classTemplate);