[fix]fix token auth (#69)

* fix tocken auth

* Further fixes to the token overwriting issue and restoration of hot reloading of tokens.json.

doris_mcp_server/utils/security.py

@@ -22,6 +22,7 @@ Implements enterprise-level authentication, authorization, SQL security validati
 
 import logging
 import re
+from contextvars import ContextVar
 from dataclasses import dataclass, field
 from datetime import datetime
 from enum import Enum
@@ -34,6 +35,10 @@ from sqlparse.tokens import Keyword, Name
 from .logger import get_logger
 from .config import DatabaseConfig
 
+# Global ContextVar for auth_context - must be a single instance shared across all modules
+# This allows token-bound database configuration to work correctly in concurrent requests
+mcp_auth_context_var: ContextVar['AuthContext'] = ContextVar('mcp_auth_context', default=None)
+
 
 class SecurityLevel(Enum):
     """Security level enumeration"""