diff --git a/assets/webui/ofdgo.js b/assets/webui/ofdgo.js
index 1baf76b..267b1f7 100644
--- a/assets/webui/ofdgo.js
+++ b/assets/webui/ofdgo.js
@@ -421,6 +421,7 @@ async function prepareOffline() {
 			return false;
 		}
 		el.offlineStatus.textContent = "可离线";
+		watchApplicationUpdates(result.checksum);
 	} catch {
 		el.offlineStatus.textContent = "未就绪";
 	}
@@ -428,6 +429,29 @@ async function prepareOffline() {
 	return true;
 }
 
+function watchApplicationUpdates(checksum) {
+	let checking = false;
+	async function check() {
+		if (checking || document.hidden || !navigator.onLine) {
+			return;
+		}
+		checking = true;
+		try {
+			const response = await fetch("./", { method: "HEAD", cache: "no-store", signal: AbortSignal.timeout(10000) });
+			const latest = response.headers.get("X-OFDGo-Checksum");
+			if (response.ok && !response.redirected && latest) {
+				el.offlineStatus.textContent = latest === checksum ? "可离线" : "可更新";
+			}
+		} catch {
+		} finally {
+			checking = false;
+		}
+	}
+	window.addEventListener("online", check);
+	document.addEventListener("visibilitychange", check);
+	check();
+}
+
 function waitForWorker(worker, target) {
 	return new Promise((resolve, reject) => {
 		function changed() {
diff --git a/assets/webui/ofdgo.sw.js b/assets/webui/ofdgo.sw.js
index 1bbe881..15dd24a 100644
--- a/assets/webui/ofdgo.sw.js
+++ b/assets/webui/ofdgo.sw.js
@@ -25,24 +25,26 @@ self.addEventListener("message", (event) => {
 	}
 	event.waitUntil((async () => {
 		try {
-			const reload = await navigator.locks.request(CACHE_PREFIX, async () => {
+			const result = await navigator.locks.request(CACHE_PREFIX, async () => {
 				const meta = await caches.open(META_CACHE);
 				await cleanBundles(meta);
 				if (type === "refresh") {
 					await updateBundle(meta);
-					return true;
+					return { reload: true };
 				}
 				const bundle = await readBundle(meta, CLIENT_PREFIX + event.source.id);
 				if (await isBundleComplete(bundle)) {
-					return false;
+					const cache = await caches.open(bundle.name);
+					const response = await cache.match(self.registration.scope);
+					return { reload: false, checksum: response.headers.get("X-OFDGo-Checksum") };
 				}
 				await currentBundle(meta);
-				return true;
+				return { reload: true };
 			});
 			if (type === "refresh") {
 				await self.skipWaiting();
 			}
-			port.postMessage({ ok: true, reload });
+			port.postMessage({ ok: true, ...result });
 		} catch (err) {
 			port.postMessage({ error: err.message });
 		} finally {