FEATURE: Allow staff users to merge posts.

app/controllers/posts_controller.rb

@@ -1,6 +1,7 @@
 require_dependency 'new_post_manager'
 require_dependency 'post_creator'
 require_dependency 'post_destroyer'
+require_dependency 'post_merger'
 require_dependency 'distributed_memoizer'
 require_dependency 'new_post_result_serializer'
 
@@ -273,6 +274,14 @@ class PostsController < ApplicationController
     render nothing: true
   end
 
+  def merge_posts
+    params.require(:post_ids)
+    posts = Post.where(id: params[:post_ids]).order(:id)
+    raise Discourse::InvalidParameters.new(:post_ids) if posts.pluck(:id) == params[:post_ids]
+    PostMerger.new(current_user, posts).merge
+    render nothing: true
+  end
+
   # Direct replies to this post
   def replies
     post = find_post_from_params