FIX: Allow triggering Discobot when bookmarking the entire topic (#27255)

plugins/discourse-narrative-bot/plugin.rb

@@ -170,11 +170,15 @@ after_initialize do
 
   self.add_model_callback(Bookmark, :after_commit, on: :create) do
     if self.user.enqueue_narrative_bot_job?
-      if self.bookmarkable_type == "Post"
+      if self.bookmarkable_type == "Post" || self.bookmarkable_type == "Topic"
+        is_topic = self.bookmarkable_type == "Topic"
+        first_post_id =
+          Post.where(topic_id: self.bookmarkable_id, post_number: 1).pick(:id) if is_topic
+
         Jobs.enqueue(
           :bot_input,
           user_id: self.user_id,
-          post_id: self.bookmarkable_id,
+          post_id: is_topic ? first_post_id : self.bookmarkable_id,
           input: "bookmark",
         )
       end

plugins/discourse-narrative-bot/spec/discourse_narrative_bot/new_user_narrative_spec.rb

@@ -287,6 +287,22 @@ RSpec.describe DiscourseNarrativeBot::NewUserNarrative do
         )
       end
 
+      it "triggers the response when bookmarking the topic" do
+        Jobs.run_later!
+        topic = Fabricate(:topic)
+        post = Fabricate(:post, topic: topic)
+        bookmark = Fabricate(:bookmark, bookmarkable: topic)
+
+        expect_job_enqueued(
+          job: :bot_input,
+          args: {
+            user_id: bookmark.user_id,
+            post_id: post.id,
+            input: "bookmark",
+          },
+        )
+      end
+
       context "when the bookmark is created" do
         let(:profile_page_url) { "#{Discourse.base_url_no_prefix}/prefix/u/#{user.username}" }
         let(:new_post) { Post.last }