#45 完了

backend/app/models/wiki_page.rb

@@ -20,6 +20,7 @@ class WikiPage < ApplicationRecord
     idx = vers.find_index { |ver| ver.id == @sha }
     @pred = vers[idx + 1]&.id
     @succ = idx.positive? ? vers[idx - 1].id : nil
+    @updated_at = vers[idx].authored_date
     @sha
   end
 
@@ -35,6 +36,10 @@ class WikiPage < ApplicationRecord
     @succ
   end
 
+  def updated_at
+    @updated_at
+  end
+
   def body
     sha = nil unless @page
     @page&.raw_data&.force_encoding('UTF-8')