feat(workflow):

1. add list operator node for filtering, sorting, limiting, and extracting list items；
2. Increase the session variable to the "file" type

api/app/schemas/app_schema.py

@@ -640,6 +640,7 @@ class CitationSource(BaseModel):
 class DraftRunResponse(BaseModel):
     """试运行响应（非流式）"""
     message: str = Field(..., description="AI 回复消息")
+    reasoning_content: Optional[str] = Field(default=None, description="深度思考内容")
     conversation_id: Optional[str] = Field(default=None, description="会话ID（用于多轮对话）")
     usage: Optional[Dict[str, Any]] = Field(default=None, description="Token 使用情况")
     elapsed_time: Optional[float] = Field(default=None, description="耗时（秒）")
@@ -647,6 +648,12 @@ class DraftRunResponse(BaseModel):
     citations: List[CitationSource] = Field(default_factory=list, description="引用来源")
     audio_url: Optional[str] = Field(default=None, description="TTS 语音URL")
 
+    def model_dump(self, **kwargs):
+        data = super().model_dump(**kwargs)
+        if not data.get("reasoning_content"):
+            data.pop("reasoning_content", None)
+        return data
+
 
 class OpeningResponse(BaseModel):
     """应用开场白响应"""