issue: #17056 : Add a reason field to the message_replace event (#17195)

Co-authored-by: 聂政 <niezheng@pjlab.org.cn>

api/core/app/task_pipeline/based_generate_task_pipeline.py

@@ -126,12 +126,12 @@ class BasedGenerateTaskPipeline:
         if self._output_moderation_handler:
             self._output_moderation_handler.stop_thread()
 
-            completion = self._output_moderation_handler.moderation_completion(
+            completion, flagged = self._output_moderation_handler.moderation_completion(
                 completion=completion, public_event=False
             )
 
             self._output_moderation_handler = None
-
-            return completion
+            if flagged:
+                return completion
 
         return None

api/core/app/task_pipeline/message_cycle_manage.py

@@ -182,10 +182,12 @@ class MessageCycleManage:
             from_variable_selector=from_variable_selector,
         )
 
-    def _message_replace_to_stream_response(self, answer: str) -> MessageReplaceStreamResponse:
+    def _message_replace_to_stream_response(self, answer: str, reason: str = "") -> MessageReplaceStreamResponse:
         """
         Message replace to stream response.
         :param answer: answer
         :return:
         """
-        return MessageReplaceStreamResponse(task_id=self._application_generate_entity.task_id, answer=answer)
+        return MessageReplaceStreamResponse(
+            task_id=self._application_generate_entity.task_id, answer=answer, reason=reason
+        )