feat: legacy features to ruby llm (#12994)

enterprise/app/services/llm/base_ai_service.rb

@@ -14,8 +14,6 @@ class Llm::BaseAiService
     setup_temperature
   end
 
-  # Returns a configured RubyLLM chat instance.
-  # Subclasses can override model/temperature via instance variables or pass them explicitly.
   def chat(model: @model, temperature: @temperature)
     RubyLLM.chat(model: model).with_temperature(temperature)
   end

enterprise/app/services/llm/legacy_base_open_ai_service.rb

@@ -1,8 +1,11 @@
 # frozen_string_literal: true
 
 # DEPRECATED: This class uses the legacy OpenAI Ruby gem directly.
-# New features should use Llm::BaseAiService with RubyLLM instead.
-# This class will be removed once all services are migrated to RubyLLM.
+# Only used for PDF/file operations that require OpenAI's files API:
+# - Captain::Llm::PdfProcessingService (files.upload for assistants)
+# - Captain::Llm::PaginatedFaqGeneratorService (uses file_id from uploaded files)
+#
+# For all other LLM operations, use Llm::BaseAiService with RubyLLM instead.
 class Llm::LegacyBaseOpenAiService
   DEFAULT_MODEL = 'gpt-4o-mini'