fix: 修复登录后跳转被立即重定向回登录页的问题

所有页面改用 useAuth hook，先检查 localStorage 再判断是否跳转

frontend/src/app/collect/page.tsx

@@ -6,11 +6,13 @@ import { useDropzone } from "react-dropzone";
 import toast from "react-hot-toast";
 import api from "@/lib/api";
 import { useAuthStore } from "@/lib/store";
+import { useAuth } from "@/hooks/useAuth";
 import { SUBJECTS } from "@/types";
 import type { MistakeOCRResponse } from "@/types";
 
 export default function CollectPage() {
   const router = useRouter();
+  const { ready } = useAuth();
   const isLoggedIn = useAuthStore((s) => s.isLoggedIn);
   const [subject, setSubject] = useState<string>("");
   const [uploading, setUploading] = useState(false);
@@ -27,9 +29,9 @@ export default function CollectPage() {
 
   const onDrop = useCallback(
     async (acceptedFiles: File[]) => {
-      if (!isLoggedIn) {
+      if (!ready) return null;
+  // isLoggedIn check removed
         router.push("/login");
-        return;
       }
       const file = acceptedFiles[0];
       if (!file) return;
@@ -103,7 +105,8 @@ export default function CollectPage() {
     }
   };
 
-  if (!isLoggedIn) {
+  if (!ready) return null;
+  // isLoggedIn check removed
     router.push("/login");
     return null;
   }

frontend/src/app/exam/page.tsx

@@ -5,10 +5,12 @@ import { useRouter } from "next/navigation";
 import toast from "react-hot-toast";
 import api from "@/lib/api";
 import { useAuthStore } from "@/lib/store";
+import { useAuth } from "@/hooks/useAuth";
 import { SUBJECTS } from "@/types";
 
 export default function ExamPage() {
   const router = useRouter();
+  const { ready } = useAuth();
   const isLoggedIn = useAuthStore((s) => s.isLoggedIn);
   const [title, setTitle] = useState("错题练习试卷");
   const [selectedSubjects, setSelectedSubjects] = useState<string[]>([]);
@@ -18,8 +20,8 @@ export default function ExamPage() {
   const [pdfUrl, setPdfUrl] = useState<string | null>(null);
 
   useEffect(() => {
-    if (!isLoggedIn) router.push("/login");
-  }, [isLoggedIn]);
+    // redirect handled by useAuth
+  }, [ready]);
 
   const toggleSubject = (s: string) => {
     setSelectedSubjects((prev) =>
@@ -53,7 +55,7 @@ export default function ExamPage() {
     window.open(downloadUrl, "_blank");
   };
 
-  if (!isLoggedIn) return null;
+  if (!ready) return null;
 
   return (
     <div className="max-w-lg mx-auto px-4 pt-6">

frontend/src/app/mistakes/page.tsx

@@ -5,11 +5,13 @@ import { useRouter } from "next/navigation";
 import toast from "react-hot-toast";
 import api from "@/lib/api";
 import { useAuthStore } from "@/lib/store";
+import { useAuth } from "@/hooks/useAuth";
 import { SUBJECTS, SUBJECT_COLORS } from "@/types";
 import type { Mistake, MistakeListResponse, AIAnalysis } from "@/types";
 
 export default function MistakesPage() {
   const router = useRouter();
+  const { ready } = useAuth();
   const isLoggedIn = useAuthStore((s) => s.isLoggedIn);
   const [mistakes, setMistakes] = useState<Mistake[]>([]);
   const [total, setTotal] = useState(0);
@@ -20,12 +22,12 @@ export default function MistakesPage() {
   const [analyzingId, setAnalyzingId] = useState<number | null>(null);
 
   useEffect(() => {
-    if (!isLoggedIn) {
+    if (!ready) return null;
+  // isLoggedIn check removed
       router.push("/login");
-      return;
     }
     loadMistakes();
-  }, [isLoggedIn, page, subject]);
+  }, [ready, page, subject]);
 
   const loadMistakes = async () => {
     setLoading(true);
@@ -72,7 +74,7 @@ export default function MistakesPage() {
     }
   };
 
-  if (!isLoggedIn) return null;
+  if (!ready) return null;
 
   const totalPages = Math.ceil(total / 20);
 

frontend/src/app/page.tsx

@@ -4,23 +4,22 @@ import { useEffect, useState } from "react";
 import { useRouter } from "next/navigation";
 import Link from "next/link";
 import { useAuthStore } from "@/lib/store";
+import { useAuth } from "@/hooks/useAuth";
 import api from "@/lib/api";
 import type { MistakeStats, ReviewProgressResponse } from "@/types";
 
 export default function DashboardPage() {
   const router = useRouter();
+  const { ready } = useAuth();
   const isLoggedIn = useAuthStore((s) => s.isLoggedIn);
   const displayName = useAuthStore((s) => s.displayName);
   const [stats, setStats] = useState<MistakeStats | null>(null);
   const [progress, setProgress] = useState<ReviewProgressResponse | null>(null);
 
   useEffect(() => {
-    if (!isLoggedIn) {
-      router.push("/login");
-      return;
-    }
+    if (!ready) return;
     loadData();
-  }, [isLoggedIn]);
+  }, [ready]);
 
   const loadData = async () => {
     try {
@@ -33,7 +32,7 @@ export default function DashboardPage() {
     } catch {}
   };
 
-  if (!isLoggedIn) return null;
+  if (!ready) return null;
 
   return (
     <div className="max-w-lg mx-auto px-4 pt-6">

frontend/src/app/review/page.tsx

@@ -5,11 +5,13 @@ import { useRouter } from "next/navigation";
 import toast from "react-hot-toast";
 import api from "@/lib/api";
 import { useAuthStore } from "@/lib/store";
+import { useAuth } from "@/hooks/useAuth";
 import type { ReviewCardResponse, ReviewTodayResponse } from "@/types";
 import { REVIEW_QUALITY_LABELS } from "@/types";
 
 export default function ReviewPage() {
   const router = useRouter();
+  const { ready } = useAuth();
   const isLoggedIn = useAuthStore((s) => s.isLoggedIn);
   const [data, setData] = useState<ReviewTodayResponse | null>(null);
   const [currentIndex, setCurrentIndex] = useState(0);
@@ -20,12 +22,9 @@ export default function ReviewPage() {
   const [analyzing, setAnalyzing] = useState(false);
 
   useEffect(() => {
-    if (!isLoggedIn) {
-      router.push("/login");
-      return;
-    }
+    if (!ready) return;
     loadToday();
-  }, [isLoggedIn]);
+  }, [ready]);
 
   const loadToday = async () => {
     try {
@@ -87,7 +86,7 @@ export default function ReviewPage() {
     }
   };
 
-  if (!isLoggedIn) return null;
+  if (!ready) return null;
 
   if (loading) {
     return (

frontend/src/app/settings/page.tsx

@@ -5,10 +5,12 @@ import { useRouter } from "next/navigation";
 import toast from "react-hot-toast";
 import api from "@/lib/api";
 import { useAuthStore } from "@/lib/store";
+import { useAuth } from "@/hooks/useAuth";
 import type { ReviewConfigResponse } from "@/types";
 
 export default function SettingsPage() {
   const router = useRouter();
+  const { ready } = useAuth();
   const isLoggedIn = useAuthStore((s) => s.isLoggedIn);
   const logout = useAuthStore((s) => s.logout);
   const displayName = useAuthStore((s) => s.displayName);
@@ -18,12 +20,12 @@ export default function SettingsPage() {
   const [mastery, setMastery] = useState(3);
 
   useEffect(() => {
-    if (!isLoggedIn) {
+    if (!ready) return null;
+  // isLoggedIn check removed
       router.push("/login");
-      return;
     }
     loadConfig();
-  }, [isLoggedIn]);
+  }, [ready]);
 
   const loadConfig = async () => {
     try {
@@ -54,7 +56,7 @@ export default function SettingsPage() {
     router.push("/login");
   };
 
-  if (!isLoggedIn) return null;
+  if (!ready) return null;
 
   return (
     <div className="max-w-lg mx-auto px-4 pt-6">

frontend/src/hooks/useAuth.ts

@@ -0,0 +1,24 @@
+import { useEffect, useState } from "react";
+import { useRouter } from "next/navigation";
+import { useAuthStore } from "@/lib/store";
+
+export function useAuth() {
+  const router = useRouter();
+  const isLoggedIn = useAuthStore((s) => s.isLoggedIn);
+  const loadFromStorage = useAuthStore((s) => s.loadFromStorage);
+  const [ready, setReady] = useState(false);
+
+  useEffect(() => {
+    if (!isLoggedIn) {
+      loadFromStorage();
+    }
+    const token = localStorage.getItem("token");
+    if (!isLoggedIn && !token) {
+      router.push("/login");
+    } else {
+      setReady(true);
+    }
+  }, [isLoggedIn]);
+
+  return { ready };
+}