🐛 fix(connection): 修复失败连接高频重试并暂停后台自动元数据拉取 #331

- 后端为失败数据库连接增加冷却窗口，避免短时间内重复真实建连
- 补充失败冷却回归测试，覆盖重复失败、冷却后重试和成功后清理场景
- 前端在后台态暂停查询页、侧边栏和表概览的自动元数据拉取
- 保持手动刷新、手动展开等显式操作行为不变

frontend/src/components/QueryEditor.tsx

@@ -11,6 +11,7 @@ import DataGrid, { GONAVI_ROW_KEY } from './DataGrid';
 import { getDataSourceCapabilities } from '../utils/dataSourceCapabilities';
 import { convertMongoShellToJsonCommand } from '../utils/mongodb';
 import { getShortcutDisplay, isEditableElement, isShortcutMatch } from '../utils/shortcuts';
+import { useAutoFetchVisibility } from '../utils/autoFetchVisibility';
 import { buildRpcConnectionConfig } from '../utils/connectionRpcConfig';
 
 const SQL_KEYWORDS = [
@@ -249,6 +250,7 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
   const setQueryOptions = useStore(state => state.setQueryOptions);
   const shortcutOptions = useStore(state => state.shortcutOptions);
   const activeTabId = useStore(state => state.activeTabId);
+  const autoFetchVisible = useAutoFetchVisibility();
 
   const currentSavedQuery = useMemo(() => {
       const savedId = String(tab.savedQueryId || '').trim();
@@ -324,6 +326,10 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
 
   // Fetch Database List
   useEffect(() => {
+      if (!autoFetchVisible) {
+          return;
+      }
+
       const fetchDbs = async () => {
           const conn = connections.find(c => c.id === currentConnectionId);
           if (!conn) return;
@@ -367,10 +373,14 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
           }
       };
       void fetchDbs();
-  }, [currentConnectionId, connections]);
+  }, [autoFetchVisible, currentConnectionId, connections]);
 
   // Fetch Metadata for Autocomplete (Cross-database)
   useEffect(() => {
+      if (!autoFetchVisible) {
+          return;
+      }
+
       const fetchMetadata = async () => {
           const conn = connections.find(c => c.id === currentConnectionId);
           if (!conn) return;
@@ -424,7 +434,7 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
           }
       };
       void fetchMetadata();
-  }, [currentConnectionId, connections, dbList]); // dbList 变化时触发重新加载
+  }, [autoFetchVisible, currentConnectionId, connections, dbList]); // dbList 变化时触发重新加载
 
   // Query ID management helpers
   const setQueryId = (id: string) => {

frontend/src/components/Sidebar.tsx

@@ -41,6 +41,7 @@ import { getDbIcon } from './DatabaseIcons';
 	import { DBGetDatabases, DBGetTables, DBQuery, DBShowCreateTable, ExportTable, OpenSQLFile, ExecuteSQLFile, CancelSQLFileExecution, CreateDatabase, RenameDatabase, DropDatabase, RenameTable, DropTable, DropView, DropFunction, RenameView } from '../../wailsjs/go/app/App';
   import { EventsOn } from '../../wailsjs/runtime/runtime';
   import { normalizeOpacityForPlatform, resolveAppearanceValues } from '../utils/appearance';
+import { useAutoFetchVisibility } from '../utils/autoFetchVisibility';
 import FindInDatabaseModal from './FindInDatabaseModal';
 import { buildRpcConnectionConfig } from '../utils/connectionRpcConfig';
 
@@ -118,6 +119,7 @@ const Sidebar: React.FC<{ onEditConnection?: (conn: SavedConnection) => void }>
   const darkMode = theme === 'dark';
   const resolvedAppearance = resolveAppearanceValues(appearance);
   const opacity = normalizeOpacityForPlatform(resolvedAppearance.opacity);
+  const autoFetchVisible = useAutoFetchVisibility();
   const [treeData, setTreeData] = useState<TreeNode[]>([]);
 
   // Background Helper (Duplicate logic for now, ideally shared)
@@ -292,6 +294,10 @@ const Sidebar: React.FC<{ onEditConnection?: (conn: SavedConnection) => void }>
   const [findInDbContext, setFindInDbContext] = useState<{ open: boolean; connectionId: string; dbName: string }>({ open: false, connectionId: '', dbName: '' });
 
   useEffect(() => {
+      if (!autoFetchVisible) {
+          return;
+      }
+
       // Refresh queries for expanded databases
       const findNode = (nodes: TreeNode[], k: React.Key): TreeNode | null => {
           for (const node of nodes) {
@@ -310,7 +316,7 @@ const Sidebar: React.FC<{ onEditConnection?: (conn: SavedConnection) => void }>
               loadTables(node);
           }
       });
-  }, [savedQueries]);
+  }, [autoFetchVisible, savedQueries]);
 
   useEffect(() => {
     setTreeData((prev) => {

frontend/src/components/TableOverview.tsx

@@ -4,6 +4,7 @@ import { TableOutlined, SearchOutlined, ReloadOutlined, SortAscendingOutlined, D
 import { useStore } from '../store';
 import { DBQuery, DBShowCreateTable, ExportTable, DropTable, RenameTable } from '../../wailsjs/go/app/App';
 import type { TabData } from '../types';
+import { useAutoFetchVisibility } from '../utils/autoFetchVisibility';
 import { buildRpcConnectionConfig } from '../utils/connectionRpcConfig';
 
 interface TableOverviewProps {
@@ -151,6 +152,7 @@ const TableOverview: React.FC<TableOverviewProps> = ({ tab }) => {
     const [viewMode, setViewMode] = useState<ViewMode>('card');
 
     const connection = useMemo(() => connections.find(c => c.id === tab.connectionId), [connections, tab.connectionId]);
+    const autoFetchVisible = useAutoFetchVisibility();
 
     const loadData = useCallback(async () => {
         if (!connection) return;
@@ -179,7 +181,12 @@ const TableOverview: React.FC<TableOverviewProps> = ({ tab }) => {
         }
     }, [connection, tab.dbName]);
 
-    useEffect(() => { loadData(); }, [loadData]);
+    useEffect(() => {
+        if (!autoFetchVisible) {
+            return;
+        }
+        void loadData();
+    }, [autoFetchVisible, loadData]);
 
     const sortedFiltered = useMemo(() => {
         let list = [...tables];