Can recover deleted topics. Deleted topics show the first post as deleted in the UI.

app/controllers/topics_controller.rb

@@ -9,6 +9,7 @@ class TopicsController < ApplicationController
                                           :update,
                                           :star,
                                           :destroy,
+                                          :recover,
                                           :status,
                                           :invite,
                                           :mute,
@@ -175,6 +176,13 @@ class TopicsController < ApplicationController
     render nothing: true
   end
 
+  def recover
+    topic = Topic.where(id: params[:topic_id]).with_deleted.first
+    guardian.ensure_can_recover_topic!(topic)
+    topic.recover!
+    render nothing: true
+  end
+
   def excerpt
     render nothing: true
   end