完成请求推送，但组装mes还有问题

backend/models/system_settings.py

@@ -0,0 +1,49 @@
+"""
+系统设置模型
+
+包含全局配置，如思考标签前后缀等。
+"""
+from typing import Optional
+from pydantic import BaseModel, Field
+from datetime import datetime
+
+
+class SystemSettings(BaseModel):
+    """
+    系统全局设置
+    
+    持久化存储到 data/system_settings.json
+    """
+    
+    # ==================== 思考标签配置 ====================
+    thinkingTagPrefix: str = Field(
+        "<thinking>",
+        description="思考标签前缀（默认：<thinking>）"
+    )
+    thinkingTagSuffix: str = Field(
+        "</thinking>",
+        description="思考标签后缀（默认：</thinking>）"
+    )
+    
+    # ==================== 当前选中的预设 ====================
+    currentPresetName: Optional[str] = Field(
+        None,
+        description="当前选中的预设名称（用于确定全局正则的作用域）"
+    )
+    
+    # ==================== 元数据 ====================
+    updatedAt: int = Field(
+        default_factory=lambda: int(datetime.now().timestamp()),
+        description="最后更新时间戳"
+    )
+    version: int = Field(1, description="版本号")
+
+
+# ==================== 默认设置 ====================
+
+DEFAULT_SYSTEM_SETTINGS = SystemSettings()
+
+
+if __name__ == '__main__':
+    import json
+    print(json.dumps(DEFAULT_SYSTEM_SETTINGS.dict(), indent=2, ensure_ascii=False))