diff --git a/api/app/core/workflow/nodes/base_node.py b/api/app/core/workflow/nodes/base_node.py
index e370dbeb..107567e1 100644
--- a/api/app/core/workflow/nodes/base_node.py
+++ b/api/app/core/workflow/nodes/base_node.py
@@ -667,6 +667,15 @@ class BaseNode(ABC):
 
     @staticmethod
     def process_model_output(content) -> str:
-        if isinstance(content, dict):
-            return content.get("text")
-        return content
+        result = ""
+        if isinstance(content, list):
+            for msg in content:
+                if isinstance(msg, dict):
+                    result += msg.get("text")
+                elif isinstance(msg, str):
+                    result += msg
+        elif isinstance(content, dict):
+            result = content.get("text")
+        elif isinstance(content, str):
+            return content
+        return result
diff --git a/api/app/core/workflow/variable/variable_objects.py b/api/app/core/workflow/variable/variable_objects.py
index 83fb06f3..7a39835c 100644
--- a/api/app/core/workflow/variable/variable_objects.py
+++ b/api/app/core/workflow/variable/variable_objects.py
@@ -2,7 +2,7 @@ from typing import Any, TypeVar, Type, Generic
 
 from deprecated import deprecated
 
-from app.core.workflow.variable.base_variable import BaseVariable, VariableType, FileObject
+from app.core.workflow.variable.base_variable import BaseVariable, VariableType, FileObject, FileType
 
 T = TypeVar("T", bound=BaseVariable)
 
@@ -75,7 +75,7 @@ class FileVariable(BaseVariable):
         raise TypeError(f"Value must be a FileObject - {type(value)}:{value}")
 
     def to_literal(self) -> str:
-        return str(self.value.model_dump())
+        return f'{"!"if self.value.type == FileType.IMAGE else ""}[file]({self.value.url})'
 
     def get_value(self) -> Any:
         return self.value.model_dump()
diff --git a/api/app/services/workflow_service.py b/api/app/services/workflow_service.py
index 508dd8ac..1c7c7304 100644
--- a/api/app/services/workflow_service.py
+++ b/api/app/services/workflow_service.py
@@ -460,21 +460,8 @@ class WorkflowService:
         input_data = {"message": payload.message, "variables": payload.variables,
                       "conversation_id": payload.conversation_id, "files": files}
 
-        # 转换 user_id 为 UUID
-        triggered_by_uuid = None
-        if payload.user_id:
-            try:
-                triggered_by_uuid = uuid.UUID(payload.user_id)
-            except (ValueError, AttributeError):
-                logger.warning(f"无效的 user_id 格式: {payload.user_id}")
-
         # 转换 conversation_id 为 UUID
-        conversation_id_uuid = None
-        if payload.conversation_id:
-            try:
-                conversation_id_uuid = uuid.UUID(payload.conversation_id)
-            except (ValueError, AttributeError):
-                logger.warning(f"无效的 conversation_id 格式: {payload.conversation_id}")
+        conversation_id_uuid = uuid.UUID(payload.conversation_id) if payload.conversation_id else None
 
         # 2. 创建执行记录
         execution = self.create_execution(
@@ -661,21 +648,8 @@ class WorkflowService:
         input_data = {"message": payload.message, "variables": payload.variables,
                       "conversation_id": payload.conversation_id, "files": files}
 
-        # 转换 user_id 为 UUID
-        triggered_by_uuid = None
-        if payload.user_id:
-            try:
-                triggered_by_uuid = uuid.UUID(payload.user_id)
-            except (ValueError, AttributeError):
-                logger.warning(f"无效的 user_id 格式: {payload.user_id}")
-
         # 转换 conversation_id 为 UUID
-        conversation_id_uuid = None
-        if payload.conversation_id:
-            try:
-                conversation_id_uuid = uuid.UUID(payload.conversation_id)
-            except (ValueError, AttributeError):
-                logger.warning(f"无效的 conversation_id 格式: {payload.conversation_id}")
+        conversation_id_uuid = uuid.UUID(payload.conversation_id) if payload.conversation_id else None
 
         # 2. 创建执行记录
         execution = self.create_execution(