Track Langfuse sessions and users (#174)

app/models/assistant/responder.rb

@@ -67,7 +67,9 @@ class Assistant::Responder
         functions: function_tool_caller.function_definitions,
         function_results: function_results,
         streamer: streamer,
-        previous_response_id: previous_response_id
+        previous_response_id: previous_response_id,
+        session_id: chat_session_id,
+        user_identifier: chat_user_identifier
       )
 
       unless response.success?
@@ -84,4 +86,18 @@ class Assistant::Responder
     def listeners
       @listeners ||= Hash.new { |h, k| h[k] = [] }
     end
+
+    def chat_session_id
+      chat&.id&.to_s
+    end
+
+    def chat_user_identifier
+      return unless chat&.user_id
+
+      ::Digest::SHA256.hexdigest(chat.user_id.to_s)
+    end
+
+    def chat
+      @chat ||= message.chat
+    end
 end