Fix session expiration handling

frontend/src/contexts/AuthContext.jsx

@@ -1,6 +1,14 @@
 import { createContext, useContext, useState, useEffect, useCallback } from 'react';
 import { login as apiLogin, logout as apiLogout, getMe } from '../api/auth';
 import { updateSignatureAppearancePreference as apiUpdateSignatureAppearancePreference } from '../api/users';
+import {
+  clearAccessToken,
+  expireSession,
+  getAccessToken,
+  getAccessTokenExpiryDelay,
+  SESSION_EXPIRED_EVENT,
+  setAccessToken,
+} from '../utils/session';
 
 const AuthContext = createContext(null);
 
@@ -8,13 +16,24 @@ export function AuthProvider({ children }) {
   const [user, setUser] = useState(null);
   const [loading, setLoading] = useState(true);
 
+  const scheduleSessionExpiry = useCallback((token) => {
+    const delay = getAccessTokenExpiryDelay(token);
+    if (delay === null) return undefined;
+
+    const timeoutId = window.setTimeout(() => {
+      expireSession();
+    }, delay);
+
+    return () => window.clearTimeout(timeoutId);
+  }, []);
+
   useEffect(() => {
-    const token = localStorage.getItem('accessToken');
+    const token = getAccessToken();
     if (token) {
       getMe()
         .then(({ data }) => setUser(data.data.user))
         .catch(() => {
-          localStorage.removeItem('accessToken');
+          clearAccessToken();
         })
         .finally(() => setLoading(false));
     } else {
@@ -22,17 +41,29 @@ export function AuthProvider({ children }) {
     }
   }, []);
 
+  useEffect(() => {
+    const handleSessionExpired = () => setUser(null);
+    window.addEventListener(SESSION_EXPIRED_EVENT, handleSessionExpired);
+    return () => window.removeEventListener(SESSION_EXPIRED_EVENT, handleSessionExpired);
+  }, []);
+
+  useEffect(() => {
+    const token = getAccessToken();
+    if (!user || !token) return undefined;
+    return scheduleSessionExpiry(token);
+  }, [scheduleSessionExpiry, user]);
+
   const login = useCallback(async (email, password) => {
     const { data } = await apiLogin({ email, password });
     const { accessToken, user: userData } = data.data;
-    localStorage.setItem('accessToken', accessToken);
+    setAccessToken(accessToken);
     setUser(userData);
     return userData;
   }, []);
 
   const logout = useCallback(async () => {
     try { await apiLogout(); } catch { /* ignore */ }
-    localStorage.removeItem('accessToken');
+    clearAccessToken();
     setUser(null);
   }, []);