fix: complete admin login redirect flow

app/routes/login.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useState } from "react";
-import { useLoaderData, useFetcher } from "@remix-run/react";
+import { useActionData, useLoaderData, useNavigation, useSubmit } from "@remix-run/react";
 import { type MetaFunction, type LoaderFunctionArgs, type ActionFunctionArgs } from "@remix-run/node";
 import { OAuthClient } from "~/api/login/oauth-client";
 import { CLIENT_OAUTH_CONFIG } from "~/config/api-config";
@@ -217,7 +217,9 @@ export async function action({ request }: ActionFunctionArgs) {
 export default function Login() {
   // const navigate = useNavigate();
   const loaderData = useLoaderData<typeof loader>();
-  const fetcher = useFetcher<{ success: boolean; error?: string }>();
+  const actionData = useActionData<typeof action>();
+  const navigation = useNavigation();
+  const submit = useSubmit();
   const [isFlipped, setIsFlipped] = useState(false);
   const [username, setUsername] = useState("");
   const [password, setPassword] = useState("");
@@ -234,8 +236,8 @@ export default function Login() {
   const retryCount = 0;
   const remainingAttempts = 5;
 
-  // 监听 fetcher 的状态
-  const isLoading = fetcher.state === "submitting" || fetcher.state === "loading";
+  // 监听当前登录表单提交状态
+  const isLoading = navigation.state !== "idle" && navigation.formAction === "/login";
 
   // 处理OAuth2.0登录
   const handleOAuthLogin = () => {
@@ -298,30 +300,26 @@ export default function Login() {
 
     console.log("📝 [Login] 提交管理员登录表单");
 
-    // ✅ 使用 fetcher 提交表单到服务端 action
+    // 使用路由提交而不是 fetcher，确保服务端 redirect 真正触发页面跳转
     const formData = new FormData();
     formData.append("username", username.trim());
     formData.append("password", password.trim());
     formData.append("redirectTo", loaderData?.redirectTo || "/");
 
-    fetcher.submit(formData, {
+    submit(formData, {
       method: "post",
       action: "/login"
     });
   };
 
-  // 处理 fetcher 响应
+  // 处理 action 返回的错误响应
   useEffect(() => {
-    if (fetcher.data) {
-      if (!fetcher.data.success && fetcher.data.error) {
-        // 登录失败，显示错误
-        console.error("❌ [Login] 登录失败:", fetcher.data.error);
-        setPasswordLoginError(fetcher.data.error);
-        toastService.error(fetcher.data.error);
-      }
-      // 登录成功的情况由 action 中的 redirect 处理，会自动跳转到 callback 页面
+    if (actionData && !actionData.success && actionData.error) {
+      console.error("❌ [Login] 登录失败:", actionData.error);
+      setPasswordLoginError(actionData.error);
+      toastService.error(actionData.error);
     }
-  }, [fetcher.data]);
+  }, [actionData]);
 
   // 显示URL错误参数的Toast提示
   useEffect(() => {