diff --git a/frontend/src/components/Sidebar.tsx b/frontend/src/components/Sidebar.tsx
index 3b0045a..d615ea6 100644
--- a/frontend/src/components/Sidebar.tsx
+++ b/frontend/src/components/Sidebar.tsx
@@ -79,8 +79,21 @@ export default function Sidebar() {
       }).catch(() => {});
     };
     fetchUnread();
-    const timer = setInterval(fetchUnread, 60000);
-    return () => clearInterval(timer);
+    let timer: ReturnType<typeof setInterval> | null = setInterval(fetchUnread, 60000);
+    // visibility 暂停：后台标签不再每 60s 拉文件夹统计
+    const onVisibility = () => {
+      if (document.hidden) {
+        if (timer) { clearInterval(timer); timer = null; }
+      } else {
+        fetchUnread();
+        timer = setInterval(fetchUnread, 60000);
+      }
+    };
+    document.addEventListener("visibilitychange", onVisibility);
+    return () => {
+      if (timer) clearInterval(timer);
+      document.removeEventListener("visibilitychange", onVisibility);
+    };
   }, []);
   const {
     metas,
diff --git a/frontend/src/components/ToolPanel/TranslationPanel.tsx b/frontend/src/components/ToolPanel/TranslationPanel.tsx
index b276b94..cd78ff2 100644
--- a/frontend/src/components/ToolPanel/TranslationPanel.tsx
+++ b/frontend/src/components/ToolPanel/TranslationPanel.tsx
@@ -4,6 +4,7 @@ import 'react-pdf/dist/Page/AnnotationLayer.css';
 import 'react-pdf/dist/Page/TextLayer.css';
 
 import { paperApi, translateApi, tasksApi, type BilingualSegment } from '@/services/api';
+import { useToast } from '@/contexts/ToastContext';
 
 pdfjs.GlobalWorkerOptions.workerSrc = new URL(
   'pdfjs-dist/build/pdf.worker.min.mjs',
@@ -66,6 +67,8 @@ export function TranslationPanel({ selectedText, paperId, paperArxivId, paperPdf
 
   const leftScrollRef = useRef<HTMLDivElement>(null);
   const rightScrollRef = useRef<HTMLDivElement>(null);
+  const pollRef = useRef<ReturnType<typeof setInterval> | null>(null); // 翻译轮询定时器（卸载时清理）
+  const { toast } = useToast();
 
   const [containerWidth, setContainerWidth] = useState(400);
   const scale = useMemo(() => {
@@ -121,30 +124,52 @@ export function TranslationPanel({ selectedText, paperId, paperArxivId, paperPdf
     setTranslating(true);
     try {
       const { task_id } = await translateApi.startBilingualPdf(paperId, mode);
-      const poll = setInterval(async () => {
-        // 后端 /tasks/{id} 返回 global_tracker.to_dict()：含 finished/success
-        const status = (await tasksApi.getStatus(task_id)) as unknown as {
-          finished: boolean;
-          success: boolean;
-          error: string | null;
-        };
-        if (!status.finished) return;
-        clearInterval(poll);
-        if (status.success) {
-          const result = (await tasksApi.getResult(task_id)) as {
-            segments?: BilingualSegment[];
-            pdf_url?: string;
+      const pollStart = Date.now();
+      const POLL_TIMEOUT_MS = 5 * 60 * 1000; // 5 分钟超时兜底
+      const MAX_ERRORS = 10; // 连续查询失败上限
+      let consecutiveErrors = 0;
+      pollRef.current = setInterval(async () => {
+        // 超时兜底：任务挂起时不再无限轮询（此前 1800 次/小时泄漏）
+        if (Date.now() - pollStart > POLL_TIMEOUT_MS) {
+          if (pollRef.current) { clearInterval(pollRef.current); pollRef.current = null; }
+          setTranslating(false);
+          toast('error', '翻译超时，请稍后重试');
+          return;
+        }
+        try {
+          // 后端 /tasks/{id} 返回 global_tracker.to_dict()：含 finished/success
+          const status = (await tasksApi.getStatus(task_id)) as unknown as {
+            finished: boolean;
+            success: boolean;
+            error: string | null;
           };
-          if (mode === 'fast' && result.segments) {
-            setSegments(result.segments);
-          } else if (mode === 'layout' && result.pdf_url) {
-            setLayoutPdfUrl(result.pdf_url);
+          consecutiveErrors = 0;
+          if (!status.finished) return;
+          if (pollRef.current) { clearInterval(pollRef.current); pollRef.current = null; }
+          if (status.success) {
+            const result = (await tasksApi.getResult(task_id)) as {
+              segments?: BilingualSegment[];
+              pdf_url?: string;
+            };
+            if (mode === 'fast' && result.segments) {
+              setSegments(result.segments);
+            } else if (mode === 'layout' && result.pdf_url) {
+              setLayoutPdfUrl(result.pdf_url);
+            }
+            setViewMode('bilingual');
+          } else {
+            toast('error', status.error || '翻译失败，请稍后重试');
+          }
+          setTranslating(false);
+        } catch {
+          // 连续错误上限：网络持续异常时中断，不再静默空转
+          consecutiveErrors += 1;
+          if (consecutiveErrors >= MAX_ERRORS) {
+            if (pollRef.current) { clearInterval(pollRef.current); pollRef.current = null; }
+            setTranslating(false);
+            toast('error', '翻译状态查询持续失败，请稍后重试');
           }
-          setViewMode('bilingual');
-        } else {
-          alert(status.error || '翻译失败，请稍后重试');
         }
-        setTranslating(false);
       }, 2000);
     } catch (err) {
       console.error('Failed to start translation:', err);
@@ -170,6 +195,13 @@ export function TranslationPanel({ selectedText, paperId, paperArxivId, paperPdf
     return () => observer.disconnect();
   }, []);
 
+  // 卸载时清理翻译轮询定时器，防泄漏
+  useEffect(() => {
+    return () => {
+      if (pollRef.current) { clearInterval(pollRef.current); pollRef.current = null; }
+    };
+  }, []);
+
   const pdfUrl = useMemo(() => {
     const token = localStorage.getItem('auth_token') || '';
     const tokenParam = token ? `?token=${encodeURIComponent(token)}` : '';
diff --git a/frontend/src/components/graph/CitationPanel.tsx b/frontend/src/components/graph/CitationPanel.tsx
index 5aa64dc..0acd35a 100644
--- a/frontend/src/components/graph/CitationPanel.tsx
+++ b/frontend/src/components/graph/CitationPanel.tsx
@@ -481,7 +481,16 @@ function RichCitationListView({ data }: { data: CitationDetail }) {
         source_paper_title: data.paper_title,
         entries,
       });
+      const pollStart = Date.now();
+      const POLL_TIMEOUT_MS = 5 * 60 * 1000; // 5 分钟超时兜底
       pollRef.current = setInterval(async () => {
+        if (Date.now() - pollStart > POLL_TIMEOUT_MS) {
+          if (pollRef.current) { clearInterval(pollRef.current); pollRef.current = undefined; }
+          setImportTask(null);
+          setShowModal(false);
+          toast("warning", "导入超时，请稍后在论文列表确认结果");
+          return;
+        }
         try {
           const status = await ingestApi.importStatus(task_id);
           setImportTask(status);
@@ -501,7 +510,7 @@ function RichCitationListView({ data }: { data: CitationDetail }) {
           setShowModal(false);
           toast("error", "导入进度查询失败，请稍后在论文列表确认结果");
         }
-      }, 1000);
+      }, 2000);
     } catch (err) {
       toast("error", `导入启动失败: ${String(err)}`);
       setShowModal(false);
diff --git a/frontend/src/contexts/GlobalTaskContext.tsx b/frontend/src/contexts/GlobalTaskContext.tsx
index 4b00a16..4b8a614 100644
--- a/frontend/src/contexts/GlobalTaskContext.tsx
+++ b/frontend/src/contexts/GlobalTaskContext.tsx
@@ -93,8 +93,23 @@ export function GlobalTaskProvider({ children }: { children: React.ReactNode })
   useEffect(() => {
     fetchTasks();
     intervalRef.current = setInterval(fetchTasks, POLL_IDLE);
+
+    // visibility 暂停：标签页不可见时停止轮询（此前后台标签 360-1800 次/小时冗余请求）
+    const onVisibility = () => {
+      if (document.hidden) {
+        if (intervalRef.current) { clearInterval(intervalRef.current); intervalRef.current = null; }
+      } else {
+        // 恢复可见：立即拉一次 + 按当前状态重启轮询
+        fetchTasks();
+        const interval = hasRunningRef.current ? POLL_FAST : POLL_IDLE;
+        intervalRef.current = setInterval(fetchTasks, interval);
+      }
+    };
+    document.addEventListener("visibilitychange", onVisibility);
+
     return () => {
       if (intervalRef.current) clearInterval(intervalRef.current);
+      document.removeEventListener("visibilitychange", onVisibility);
     };
   }, [fetchTasks]);
 
diff --git a/frontend/src/services/api.ts b/frontend/src/services/api.ts
index 8805f8b..df38701 100644
--- a/frontend/src/services/api.ts
+++ b/frontend/src/services/api.ts
@@ -2,6 +2,7 @@
  * PaperMind - API 服务层
  * @author Color2333
  */
+import { retryAsync } from "@/lib/errorHandler";
 import type {
   SystemStatus,
   Topic,
@@ -192,8 +193,10 @@ async function request<T>(path: string, options: RequestInit = {}): Promise<T> {
   return resp.json();
 }
 
+// GET 幂等，套 retryAsync（3 次指数退避，仅 NETWORK/SERVER/timeout 重试）；
+// POST/PATCH/PUT/DELETE 不套，避免重复写入
 function get<T>(path: string, opts?: { signal?: AbortSignal }) {
-  return request<T>(path, { signal: opts?.signal });
+  return retryAsync(() => request<T>(path, { signal: opts?.signal }));
 }
 
 function post<T>(path: string, body?: unknown, opts?: { signal?: AbortSignal }) {