diff --git a/internal/server/server.go b/internal/server/server.go
index 630080f..7f29bcc 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -260,8 +260,7 @@ func (s *Server) handleSession(w http.ResponseWriter, r *http.Request) {
 	}
 	session, csrfToken, err := s.auth.CSRFToken(r.Context(), sessionToken, existingCSRF)
 	if errors.Is(err, auth.ErrUnauthorized) {
-		s.clearAuthCookies(w)
-		writeError(w, http.StatusUnauthorized, "unauthorized", "authentication is required")
+		s.authenticationRequired(w, r)
 		return
 	}
 	if err != nil {
@@ -296,8 +295,7 @@ func (s *Server) handleLogout(w http.ResponseWriter, r *http.Request) {
 	if _, err := s.auth.ValidateCSRF(r.Context(), sessionToken, csrfToken); err != nil {
 		switch {
 		case errors.Is(err, auth.ErrUnauthorized):
-			s.clearAuthCookies(w)
-			writeError(w, http.StatusUnauthorized, "unauthorized", "authentication is required")
+			s.authenticationRequired(w, r)
 		case errors.Is(err, auth.ErrInvalidCSRF):
 			writeError(w, http.StatusForbidden, "invalid_csrf", "CSRF validation failed")
 		default:
@@ -346,8 +344,7 @@ func (s *Server) handleAPI(w http.ResponseWriter, r *http.Request) {
 		if _, err := s.auth.ValidateCSRF(r.Context(), sessionToken, csrfToken); err != nil {
 			switch {
 			case errors.Is(err, auth.ErrUnauthorized):
-				s.clearAuthCookies(w)
-				writeError(w, http.StatusUnauthorized, "unauthorized", "authentication is required")
+				s.authenticationRequired(w, r)
 			case errors.Is(err, auth.ErrInvalidCSRF):
 				writeError(w, http.StatusForbidden, "invalid_csrf", "CSRF validation failed")
 			default:
@@ -419,7 +416,7 @@ func (s *Server) decodeJSON(w http.ResponseWriter, r *http.Request, destination
 func (s *Server) sessionToken(w http.ResponseWriter, r *http.Request) (string, bool) {
 	cookie, err := r.Cookie(sessionCookieName)
 	if err != nil || cookie.Value == "" {
-		writeError(w, http.StatusUnauthorized, "unauthorized", "authentication is required")
+		s.authenticationRequired(w, r)
 		return "", false
 	}
 	return cookie.Value, true
@@ -432,8 +429,7 @@ func (s *Server) requireAuthenticated(w http.ResponseWriter, r *http.Request) bo
 	}
 	if _, err := s.auth.Authenticate(r.Context(), sessionToken); err != nil {
 		if errors.Is(err, auth.ErrUnauthorized) {
-			s.clearAuthCookies(w)
-			writeError(w, http.StatusUnauthorized, "unauthorized", "authentication is required")
+			s.authenticationRequired(w, r)
 		} else {
 			s.logger.Error("request authentication failed", "error", err)
 			writeError(w, http.StatusInternalServerError, "internal_error", "an internal error occurred")
@@ -443,6 +439,21 @@ func (s *Server) requireAuthenticated(w http.ResponseWriter, r *http.Request) bo
 	return true
 }
 
+// authenticationRequired preserves JSON semantics for API clients while
+// making a direct browser navigation land on the login screen instead of a
+// raw {"error":...} document. Frontend fetches explicitly request JSON and
+// are handled by the shared vocat:unauthorized event.
+func (s *Server) authenticationRequired(w http.ResponseWriter, r *http.Request) {
+	s.clearAuthCookies(w)
+	w.Header().Set("Cache-Control", "no-store")
+	if (r.Method == http.MethodGet || r.Method == http.MethodHead) &&
+		strings.Contains(strings.ToLower(r.Header.Get("Accept")), "text/html") {
+		http.Redirect(w, r, "/login", http.StatusSeeOther)
+		return
+	}
+	writeError(w, http.StatusUnauthorized, "unauthorized", "authentication is required")
+}
+
 func (s *Server) validateDoubleSubmitCSRF(w http.ResponseWriter, r *http.Request) (string, bool) {
 	headerToken := r.Header.Get(csrfHeaderName)
 	cookie, err := r.Cookie(csrfCookieName)
diff --git a/internal/server/server_test.go b/internal/server/server_test.go
index da6c2d7..25858a3 100644
--- a/internal/server/server_test.go
+++ b/internal/server/server_test.go
@@ -241,6 +241,30 @@ func TestUnifiedAPIErrors(t *testing.T) {
 	}
 }
 
+func TestUnauthenticatedBrowserNavigationRedirectsToLogin(t *testing.T) {
+	app := newTestApplication(t)
+	client := *app.client
+	client.CheckRedirect = func(_ *http.Request, _ []*http.Request) error {
+		return http.ErrUseLastResponse
+	}
+	request, err := http.NewRequest(http.MethodGet, app.server.URL+"/api/devices", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	request.Header.Set("Accept", "text/html,application/xhtml+xml")
+	response, err := client.Do(request)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer response.Body.Close()
+	if response.StatusCode != http.StatusSeeOther {
+		t.Fatalf("navigation status = %d", response.StatusCode)
+	}
+	if location := response.Header.Get("Location"); location != "/login" {
+		t.Fatalf("navigation location = %q", location)
+	}
+}
+
 func TestNewRequiresIndex(t *testing.T) {
 	database, err := store.Open(context.Background(), ":memory:")
 	if err != nil {
diff --git a/web/src/App.tsx b/web/src/App.tsx
index b060371..a51910c 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -45,7 +45,8 @@ function RequireAuth({ children }: { children: ReactElement }) {
   const location = useLocation();
   if (!ready) return <LoadingScreen />;
   if (!isAuthenticated) {
-    return <Navigate to={`/login?redirect=${encodeURIComponent(location.pathname)}`} replace />;
+    const redirect = `${location.pathname}${location.search}${location.hash}`;
+    return <Navigate to={`/login?redirect=${encodeURIComponent(redirect)}`} replace />;
   }
   return children;
 }
diff --git a/web/src/api.ts b/web/src/api.ts
index f68f1d3..e687b01 100644
--- a/web/src/api.ts
+++ b/web/src/api.ts
@@ -9,6 +9,18 @@ import { tl } from "./lib/i18n";
 
 const CSRF_KEY = "vocat.csrf";
 
+// Authenticated pages and same-origin plugin frames share this signal. Clear
+// the mutation token immediately so a revoked session cannot leave stale auth
+// state behind in the browser.
+export function notifyUnauthorized() {
+  try {
+    sessionStorage.removeItem(CSRF_KEY);
+  } catch {
+    /* ignore unavailable storage */
+  }
+  window.dispatchEvent(new Event("vocat:unauthorized"));
+}
+
 function isMutation(method: string) {
   return !["GET", "HEAD", "OPTIONS"].includes(method.toUpperCase());
 }
@@ -94,14 +106,17 @@ export async function api<T>(path: string, options: RequestOptions = {}): Promis
         : JSON.stringify(snakeize(options.body)),
   });
 
-  if (options.raw) return response as T;
+  if (options.raw) {
+    if (response.status === 401) notifyUnauthorized();
+    return response as T;
+  }
   const contentType = response.headers.get("content-type") || "";
   const payload = contentType.includes("application/json")
     ? await response.json()
     : { message: await response.text() };
   const normalized = camelize<Record<string, unknown>>(payload);
   if (!response.ok) {
-    if (response.status === 401) window.dispatchEvent(new Event("vocat:unauthorized"));
+    if (response.status === 401) notifyUnauthorized();
     const nested = normalized.error;
     const detail = nested && typeof nested === "object"
       ? {
diff --git a/web/src/components/devices/shared.ts b/web/src/components/devices/shared.ts
index a74ca27..f43bbcc 100644
--- a/web/src/components/devices/shared.ts
+++ b/web/src/components/devices/shared.ts
@@ -3,6 +3,7 @@ import { message } from "../ui";
 import type { DeviceDetail, DeviceModem, ModemPnn } from "./types";
 import { tl } from "../../lib/i18n";
 import { lookupCarrier } from "../../lib/carrier";
+import { notifyUnauthorized } from "../../api";
 
 /* ---------------------------------------------------------------------------
  * Lifecycle / status helpers (ported from the VoHive reference).
@@ -283,6 +284,7 @@ export async function readEventStream(
     credentials: "include",
     signal: handlers.signal,
   });
+  if (response.status === 401) notifyUnauthorized();
   if (!response.ok) throw new Error((await response.text()) || `HTTP ${response.status}`);
   if (!response.body) throw new Error("No stream body");
 
diff --git a/web/src/pages/SettingsPage.tsx b/web/src/pages/SettingsPage.tsx
index 4d05e6b..01f0070 100644
--- a/web/src/pages/SettingsPage.tsx
+++ b/web/src/pages/SettingsPage.tsx
@@ -271,9 +271,12 @@ export default function SettingsPage() {
     if (!confirmed) return;
     setApplyingUpdate(true);
     try {
-      const data = await api<{ message?: string }>("/system/update/apply", { method: "POST", body: {} });
+      const data = await api<{ message?: string; reauthenticationRequired?: boolean }>("/system/update/apply", { method: "POST", body: {} });
       message.success(data?.message || t("正在更新..."));
-      window.setTimeout(() => window.location.reload(), 5000);
+      window.setTimeout(() => {
+        if (data?.reauthenticationRequired) window.location.replace("/login");
+        else window.location.reload();
+      }, 1500);
     } catch (e) {
       message.error(e instanceof Error ? e.message : t("应用更新失败"));
     } finally {
diff --git a/web/src/store/auth.tsx b/web/src/store/auth.tsx
index f2678ab..d9fc01b 100644
--- a/web/src/store/auth.tsx
+++ b/web/src/store/auth.tsx
@@ -62,6 +62,15 @@ export function AuthProvider({ children }: { children: ReactNode }) {
     }
   }, []);
 
+  useEffect(() => {
+    const unauthorized = () => {
+      setUser(null);
+      setReady(true);
+    };
+    window.addEventListener("vocat:unauthorized", unauthorized);
+    return () => window.removeEventListener("vocat:unauthorized", unauthorized);
+  }, []);
+
   useEffect(() => {
     void refresh();
   }, [refresh]);