fix(message_summary): stop rendering failed workflow output

plugins/message_summary/main.py

@@ -298,6 +298,9 @@ class MessageSummaryPlugin(MessagePluginInterface):
 
     def _append_usage_info(self, answer: str, metadata: Dict[str, Any]) -> str:
         """把 token 统计追加到总结文本末尾"""
+        if not answer or not answer.strip():
+            return answer
+
         usage = metadata.get("usage", {}) if metadata else {}
         if not usage:
             return answer
@@ -331,6 +334,11 @@ class MessageSummaryPlugin(MessagePluginInterface):
     def _parse_workflow_response(self, response_data: Dict[str, Any]) -> Tuple[str, Dict[str, Any]]:
         """解析 Dify workflow 响应"""
         payload = (response_data or {}).get("data", {}) or {}
+        status = str(payload.get("status", "")).strip().lower()
+        if status and status not in {"succeeded", "success", "partial-succeeded"}:
+            error_message = payload.get("error") or response_data.get("message") or f"workflow status={status}"
+            raise RuntimeError(str(error_message))
+
         outputs = payload.get("outputs", {}) or {}
         answer = ""
 
@@ -478,6 +486,9 @@ class MessageSummaryPlugin(MessagePluginInterface):
                             answer = response_data.get("answer", "")
                             metadata = response_data.get("metadata", {})
 
+                        if not answer or not answer.strip():
+                            raise RuntimeError("Dify 未返回有效总结内容")
+
                         answer = self._clean_summary_output(answer)
                         spath = ""
                         answer = self._append_usage_info(answer, metadata)