Avoid loading summaries for other topic lists

Author: romanrizzi

lib/summarization/entry_point.rb

@@ -33,14 +33,24 @@ def inject_into(plugin)
           :topic_list_item,
           :ai_topic_gist,
           include_condition: -> do
+            # Hack(roman): Not ideal but at this point I don't have a better way of knowing if I'm serializing items for the hot filter.
+            # If the association wasn't loaded, assume don't care about summaries, and including it anyway will result in multiple n+1 queries.
+            # In the future, the serializer could have more informacion about the topic list, so we don't depend on this.
             SiteSetting.ai_summarization_enabled &&
-              SiteSetting.ai_summarize_max_hot_topics_gists_per_batch > 0
+              SiteSetting.ai_summarize_max_hot_topics_gists_per_batch > 0 &&
+              object.ai_summaries.loaded?
           end,
-        ) { object.ai_summaries.to_a.first&.summarized_text }
+        ) do
+          summaries = object.ai_summaries.to_a
+
+          # Summaries should always have one element here.
+          # This is an extra safeguard to avoid including regular summaries.
+          summaries.find { |s| s.summary_type == "gist" }&.summarized_text
+        end
 
         # To make sure hot topic gists are inmediately up to date, we rely on this event
         # instead of using a scheduled job.
-        plugin.on(:topic_hot_scores_updated) { Jobs.enqueue(:summarize_hot_topics_batch) }
+        plugin.on(:topic_hot_scores_updated) { Jobs.enqueue(:hot_topics_gist_batch) }
       end
     end
   end

spec/lib/modules/summarization/entry_point_spec.rb

@@ -59,8 +59,26 @@
 
             expect(serialized[:ai_topic_gist]).to be_present
           end
+
+          it "doesn't include the summary when looking at other topic lists" do
+            gist_topic = topic_query.list_latest.topics.find { |t| t.id == topic_ai_gist.target_id }
+
+            serialized =
+              TopicListItemSerializer.new(gist_topic, scope: Guardian.new, root: false).as_json
+
+            expect(serialized[:ai_topic_gist]).to be_nil
+          end
         end
       end
     end
   end
+
+  describe "#on topic_hot_scores_updated" do
+    it "queues a job to generate gists" do
+      expect { DiscourseEvent.trigger(:topic_hot_scores_updated) }.to change(
+        Jobs::HotTopicsGistBatch.jobs,
+        :size,
+      ).by(1)
+    end
+  end
 end