diff --git a/api/app/core/workflow/nodes/llm/node.py b/api/app/core/workflow/nodes/llm/node.py
index 14bcb8ed..761a2e22 100644
--- a/api/app/core/workflow/nodes/llm/node.py
+++ b/api/app/core/workflow/nodes/llm/node.py
@@ -68,12 +68,13 @@ class LLMNode(BaseNode):
     - ai/assistant: AI 消息（AIMessage）
     """
 
-    def _output_types(self) -> dict[str, VariableType]:
-        return {"output": VariableType.STRING}
-
     def __init__(self, node_config: dict[str, Any], workflow_config: dict[str, Any]):
         super().__init__(node_config, workflow_config)
         self.typed_config: LLMNodeConfig | None = None
+        self.messages = []
+
+    def _output_types(self) -> dict[str, VariableType]:
+        return {"output": VariableType.STRING}
 
     def _render_context(self, message: str, variable_pool: VariablePool):
         context = f"<context>{self._render_template(self.typed_config.context, variable_pool)}</context>"
diff --git a/api/app/services/workflow_service.py b/api/app/services/workflow_service.py
index db50ce88..fb88f804 100644
--- a/api/app/services/workflow_service.py
+++ b/api/app/services/workflow_service.py
@@ -2,7 +2,6 @@
 工作流服务层
 """
 import datetime
-import json
 import logging
 import uuid
 from typing import Any, Annotated, Optional
@@ -448,13 +447,9 @@ class WorkflowService:
                 message=f"工作流配置不存在: app_id={app_id}"
             )
 
-        json_files = []
-        for file in payload.files:
-            file_json = json.loads(file.model_dump_json())
-            json_files.append(file_json)
         input_data = {"message": payload.message, "variables": payload.variables,
                       "conversation_id": payload.conversation_id,
-                      "files": json_files
+                      "files": [file.model_dump(mode='json') for file in payload.files]
                       }
 
         # 转换 conversation_id 为 UUID
@@ -642,13 +637,9 @@ class WorkflowService:
                 message=f"工作流配置不存在: app_id={app_id}"
             )
 
-        json_files = []
-        for file in payload.files:
-            file_json = json.loads(file.model_dump_json())
-            json_files.append(file_json)
         input_data = {"message": payload.message, "variables": payload.variables,
                       "conversation_id": payload.conversation_id,
-                      "files": json_files
+                      "files": [file.model_dump(mode='json') for file in payload.files]
                       }
 
         # 转换 conversation_id 为 UUID