perf: 页面切换零延迟渲染、消除动态 chunk 加载白屏与二次 loading 闪烁、重构微滑淡入过渡

web-next/src/pages/update/UpdatePage.tsx

@@ -1,3 +1,6 @@
+// In-memory cache across page transitions for zero-latency instant rendering
+let updateInfoCache: any = null;
+
 import { BeamLoading, BeamBar } from "../../components/BeamLoading";
 import { useState, useEffect, useRef, useMemo, type ReactNode } from "react";
 import {
@@ -302,7 +305,9 @@ export default function UpdatePage({
     setLoading(true);
     setError("");
     try {
-      setLiveInfo(await api<UpdateInfo>("/api/update/status"));
+      const res = await api<UpdateInfo>("/api/update/status");
+      setLiveInfo(res);
+      updateInfoCache = res;
     } catch (e) {
       setError((e as Error).message);
     } finally {