UX: update topic small action post to add link for new linked topic URL (#11132)

https://meta.discourse.org/t/linked-topics-splitting-and-managing-megatopics/168992/4?u=techapj

app/jobs/regular/create_linked_topic.rb

@@ -75,8 +75,12 @@ module Jobs
           ON CONFLICT (topic_id, user_id) DO NOTHING
         SQL
 
-        # add moderator post to old topic
-        parent_topic.add_moderator_post(system_user, I18n.t('create_linked_topic.moderator_post_raw', new_url: new_topic.url))
+        # update small action post on old topic to add new topic link
+        small_action_post = Post.where(topic_id: parent_topic_id, post_type: Post.types[:small_action], action_code: "closed.enabled").last
+        if small_action_post.present?
+          small_action_post.raw = "#{small_action_post.raw} #{I18n.t('create_linked_topic.small_action_post_raw', new_title: "[#{new_topic_title}](#{new_topic.url})")}"
+          small_action_post.save!
+        end
       end
       @post_creator.enqueue_jobs if @post_creator
     end

config/locales/server.en.yml

@@ -4945,4 +4945,4 @@ en:
       one: "%{topic_title} (Part %{count})"
       other: "%{topic_title} (Part %{count})"
     post_raw: "Continuing the discussion from %{parent_url}.\n\nPrevious discussions:\n\n%{previous_topics}"
-    moderator_post_raw: "Continue discussion here: %{new_url}"
+    small_action_post_raw: "Continue discussion at %{new_title}."

spec/jobs/create_linked_topic_spec.rb

@@ -37,6 +37,7 @@ describe Jobs::CreateLinkedTopic do
     end
 
     it 'creates a linked topic' do
+      small_action_post = Fabricate(:post, topic: topic, post_type: Post.types[:small_action], action_code: "closed.enabled")
       Jobs::CreateLinkedTopic.new.execute(post_id: post.id)
 
       raw_title = topic.title
@@ -44,7 +45,7 @@ describe Jobs::CreateLinkedTopic do
       new_topic = Topic.last
       linked_topic = new_topic.linked_topic
       expect(topic.title).to include(I18n.t("create_linked_topic.topic_title_with_sequence", topic_title: raw_title, count: 1))
-      expect(topic.posts.last.raw).to eq(I18n.t('create_linked_topic.moderator_post_raw', new_url: new_topic.url))
+      expect(topic.posts.last.raw).to include(I18n.t('create_linked_topic.small_action_post_raw', new_title: "[#{new_topic.title}](#{new_topic.url})"))
       expect(new_topic.title).to include(I18n.t("create_linked_topic.topic_title_with_sequence", topic_title: raw_title, count: 2))
       expect(new_topic.first_post.raw).to include(topic.url)
       expect(new_topic.topic_users.count).to eq(3)