refactor(api): implement caching for tunnel and version status endpoints

src/app/api/tunnel/status/route.js

@@ -1,11 +1,23 @@
 import { NextResponse } from "next/server";
 import { getTunnelStatus, getTailscaleStatus, getDownloadStatus } from "@/lib/tunnel";
 
+const STATUS_CACHE_TTL_MS = 3000; // coalesce rapid polls; underlying probes already cache 10s
+
+// Survive hot reload; one cache per process. Only tunnel/tailscale probes are cached —
+// download progress stays live so the enable/download UI updates smoothly.
+const statusCache = (global.__tunnelStatusCache ??= { value: null, fetchedAt: 0 });
+
 export async function GET() {
   try {
-    const [tunnel, tailscale] = await Promise.all([getTunnelStatus(), getTailscaleStatus()]);
+    let probes = statusCache.value;
+    if (!probes || Date.now() - statusCache.fetchedAt >= STATUS_CACHE_TTL_MS) {
+      const [tunnel, tailscale] = await Promise.all([getTunnelStatus(), getTailscaleStatus()]);
+      probes = { tunnel, tailscale };
+      statusCache.value = probes;
+      statusCache.fetchedAt = Date.now();
+    }
     const download = getDownloadStatus();
-    return NextResponse.json({ tunnel, tailscale, download });
+    return NextResponse.json({ ...probes, download });
   } catch (error) {
     console.error("Tunnel status error:", error);
     return NextResponse.json({ error: error.message }, { status: 500 });

src/app/api/version/route.js

@@ -2,6 +2,10 @@ import https from "https";
 import pkg from "../../../../package.json" with { type: "json" };
 
 const NPM_PACKAGE_NAME = "9router";
+const VERSION_CACHE_TTL_MS = 3600000; // cache npm latest lookup for 1h
+
+// Survive hot reload; one cache per process
+const versionCache = (global.__npmVersionCache ??= { value: null, fetchedAt: 0 });
 
 // Fetch latest version from npm registry
 function fetchLatestVersion() {
@@ -36,8 +40,20 @@ function compareVersions(a, b) {
   return 0;
 }
 
+async function getLatestVersionCached() {
+  if (versionCache.value && Date.now() - versionCache.fetchedAt < VERSION_CACHE_TTL_MS) {
+    return versionCache.value;
+  }
+  const latest = await fetchLatestVersion();
+  if (latest) {
+    versionCache.value = latest;
+    versionCache.fetchedAt = Date.now();
+  }
+  return latest;
+}
+
 export async function GET() {
-  const latestVersion = await fetchLatestVersion();
+  const latestVersion = await getLatestVersionCached();
   const currentVersion = pkg.version;
   const hasUpdate = latestVersion ? compareVersions(latestVersion, currentVersion) > 0 : false;