fix: 增强代理密码脱敏策略并补充异常日志

- 密码脱敏阈值从 4 提升至 8，短密码全部遮蔽
- 为系统代理获取、proxy_node 解析、代理 URL 构建添加 warning 日志

src/api/admin/proxy_nodes/routes.py

@@ -27,10 +27,10 @@ pipeline = ApiRequestPipeline()
 
 
 def _mask_password(password: str | None) -> str | None:
-    """脱敏密码，仅显示前2位和后2位"""
+    """脱敏密码，仅显示前2位和后2位（长度不足 8 时全部遮蔽）"""
     if not password:
         return None
-    if len(password) <= 4:
+    if len(password) < 8:
         return "****"
     return password[:2] + "****" + password[-2:]
 

src/clients/http_client.py

@@ -142,7 +142,8 @@ def get_system_proxy_config() -> dict[str, Any] | None:
             result = None
         _system_proxy_cache = (result, now + _SYSTEM_PROXY_CACHE_TTL)
         return result
-    except Exception:
+    except Exception as exc:
+        logger.warning("获取系统默认代理配置失败: {}", exc)
         _system_proxy_cache = (None, now + _SYSTEM_PROXY_CACHE_TTL)
         return None
     finally:
@@ -170,7 +171,8 @@ def resolve_ops_proxy(connector_config: dict[str, Any] | None) -> str | None:
         if isinstance(node_id, str) and node_id.strip():
             try:
                 return build_proxy_url({"node_id": node_id.strip(), "enabled": True})
-            except Exception:
+            except Exception as exc:
+                logger.warning("解析 proxy_node_id={} 失败，回退到直连: {}", node_id, exc)
                 return None
 
         # 旧格式：直接返回 proxy URL 字符串
@@ -183,7 +185,8 @@ def resolve_ops_proxy(connector_config: dict[str, Any] | None) -> str | None:
     if system_proxy:
         try:
             return build_proxy_url(system_proxy)
-        except Exception:
+        except Exception as exc:
+            logger.warning("构建系统默认代理 URL 失败: {}", exc)
             return None
 
     return None