FIX: Chat titler was still using the old code after LLM migration (#314)

lib/modules/ai_helper/chat_thread_titler.rb

@@ -7,26 +7,34 @@ module DiscourseAi
         @thread = thread
       end
 
+      def suggested_title
+        return nil if thread_content.blank?
+
+        prompt = CompletionPrompt.enabled_by_name("generate_titles")
+        raise Discourse::InvalidParameters.new(:mode) if !prompt
+
+        response =
+          DiscourseAi::AiHelper::Assistant.new.generate_and_send_prompt(
+            prompt,
+            thread_content,
+            thread.original_message_user,
+          )
+        response.dig(:suggestions)&.first
+      end
+
+      private
+
+      attr_reader :thread
+
       def thread_content
         # Replace me by a proper API call
-        @thread
+        thread
           .chat_messages
           .joins(:user)
           .pluck(:username, :message)
           .map { |username, message| "#{username}: #{message}" }
           .join("\n")
       end
-
-      def suggested_title
-        return nil if thread_content.blank?
-
-        prompt = CompletionPrompt.enabled_by_name(id: "generate_titles")
-        raise Discourse::InvalidParameters.new(:mode) if !prompt
-
-        response =
-          DiscourseAi::AiHelper::LlmPrompt.new.generate_and_send_prompt(prompt, thread_content)
-        response.dig(:suggestions)&.first
-      end
     end
   end
 end

spec/lib/modules/ai_helper/chat_thread_titler_spec.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+RSpec.describe DiscourseAi::AiHelper::ChatThreadTitler do
+  subject(:titler) { described_class.new(thread) }
+
+  fab!(:thread) { Fabricate(:chat_thread) }
+  fab!(:user) { Fabricate(:user) }
+
+  describe "#suggested_title" do
+    it "suggest the first option from the generate_titles prompt" do
+      titles =
+        "The solitary horse*The horse etched in gold*A horse's infinite journey*A horse lost in time*A horse's last ride"
+      expected_title = titles.split("*").first
+
+      result =
+        DiscourseAi::Completions::LLM.with_prepared_responses([titles]) { titler.suggested_title }
+
+      expect(result).to eq(expected_title)
+    end
+  end
+end