diff --git a/assets/webui/index.html b/assets/webui/index.html
index 89f0a09..abce338 100644
--- a/assets/webui/index.html
+++ b/assets/webui/index.html
@@ -12,56 +12,59 @@
 </head>
 <body>
 	<div class="app">
-		<header class="toolbar app-bar">
-			<input id="ofdInput" class="file-input" type="file" accept=".ofd,.pdf">
-			<input id="fontInput" class="file-input" type="file" accept=".ttf,.otf,.ttc,font/*" multiple>
-			<input id="fontDirectoryInput" class="file-input" type="file" webkitdirectory multiple>
-			<div class="tool-group">
-				<button id="ofdButton" class="icon-button" type="button" title="打开"><span class="open-icon"></span></button>
-				<button id="newButton" class="icon-button" type="button" title="新建"><span class="new-icon"></span></button>
-				<button id="saveButton" class="icon-button" type="button" title="保存" disabled><span class="save-icon"></span></button>
-				<button id="editButton" class="icon-button" type="button" title="编辑" data-pressed="false" disabled><span class="edit-icon"></span></button>
-				<button id="convertButton" class="icon-button" type="button" title="转换"><span>&#8644;</span></button>
-				<button id="togglePagesButton" class="icon-button" type="button" title="页面栏" data-pressed="true">&#9776;</button>
-				<button id="toggleMetaButton" class="icon-button" type="button" title="信息栏" data-pressed="true">&#9432;</button>
-			</div>
-			<div class="toolbar-space"></div>
-			<div class="tool-group">
-				<button id="prevButton" class="icon-button arrow-prev" type="button" title="上一页" disabled></button>
-				<label class="page-control">
-					<input id="pageInput" type="number" min="1" value="0" disabled>
-					<span>/</span>
-					<span id="pageTotal">0</span>
-				</label>
-				<button id="nextButton" class="icon-button arrow-next" type="button" title="下一页" disabled></button>
-			</div>
-			<div class="tool-group">
-				<button id="zoomOutButton" class="icon-button" type="button" title="缩小" disabled>-</button>
-				<span id="zoomLabel" class="zoom-label">100%</span>
-				<button id="zoomInButton" class="icon-button" type="button" title="放大" disabled>+</button>
-				<button id="fitButton" class="button" type="button" data-short="宽" disabled>适宽</button>
-				<button id="fitHeightButton" class="button" type="button" data-short="高" disabled>适高</button>
-				<button id="rotateButton" class="button" type="button" data-short="转" disabled>旋转</button>
-				<button id="panButton" class="button" type="button" data-short="拖" data-pressed="false" disabled>拖动</button>
-				<button id="continuousButton" class="button" type="button" data-short="连" data-pressed="false" disabled>连续</button>
-				<button id="annotationButton" class="button" type="button" data-short="注" data-pressed="true">注解</button>
-			</div>
-			<div class="tool-group">
-				<button id="renderVectorButton" class="button" type="button" data-short="矢" data-pressed="true" disabled>矢量</button>
-				<button id="renderRasterButton" class="button" type="button" data-short="位" data-pressed="false" disabled>位图</button>
-			</div>
-			<div class="tool-group">
-				<label class="toolbar-select"><select id="exportFormat" class="format-select" title="导出格式" disabled></select><span id="formatValue"></span></label>
-				<label class="toolbar-select"><select id="imageDPI" class="format-select" title="输出精度" disabled>
-					<option value="96">96 dpi</option>
-					<option value="150">150 dpi</option>
-					<option value="300" selected>300 dpi</option>
-					<option value="600">600 dpi</option>
-				</select><span id="dpiValue">300</span></label>
-				<label class="toolbar-select"><select id="outputCompression" class="format-select" title="压缩模式" disabled><option value="0">原始</option><option value="1">无损</option><option value="2">轻压</option><option value="3">均衡</option><option value="4">强压</option></select><span id="compressionValue" data-short="原">原始</span></label>
-				<button id="exportPageButton" class="button" type="button" data-short="单" disabled>单页</button>
-				<button id="exportButton" class="button" type="button" data-short="多" disabled>文档</button>
+		<header class="toolbar-frame">
+			<div class="toolbar app-bar">
+				<input id="ofdInput" class="file-input" type="file" accept=".ofd,.pdf">
+				<input id="fontInput" class="file-input" type="file" accept=".ttf,.otf,.ttc,font/*" multiple>
+				<input id="fontDirectoryInput" class="file-input" type="file" webkitdirectory multiple>
+				<div class="tool-group">
+					<button id="ofdButton" class="icon-button" type="button" title="打开"><span class="open-icon"></span></button>
+					<button id="newButton" class="icon-button" type="button" title="新建"><span class="new-icon"></span></button>
+					<button id="saveButton" class="icon-button" type="button" title="保存" disabled><span class="save-icon"></span></button>
+					<button id="editButton" class="icon-button" type="button" title="编辑" data-pressed="false" disabled><span class="edit-icon"></span></button>
+					<button id="convertButton" class="icon-button" type="button" title="转换"><span>&#8644;</span></button>
+					<button id="togglePagesButton" class="icon-button" type="button" title="页面栏" data-pressed="true">&#9776;</button>
+					<button id="toggleMetaButton" class="icon-button" type="button" title="信息栏" data-pressed="true">&#9432;</button>
+				</div>
+				<div class="toolbar-space"></div>
+				<div class="tool-group">
+					<button id="prevButton" class="icon-button arrow-prev" type="button" title="上一页" disabled></button>
+					<label class="page-control">
+						<input id="pageInput" type="number" min="1" value="0" disabled>
+						<span>/</span>
+						<span id="pageTotal">0</span>
+					</label>
+					<button id="nextButton" class="icon-button arrow-next" type="button" title="下一页" disabled></button>
+				</div>
+				<div class="tool-group">
+					<button id="zoomOutButton" class="icon-button" type="button" title="缩小" disabled>-</button>
+					<span id="zoomLabel" class="zoom-label">100%</span>
+					<button id="zoomInButton" class="icon-button" type="button" title="放大" disabled>+</button>
+					<button id="fitButton" class="button" type="button" data-short="宽" disabled>适宽</button>
+					<button id="fitHeightButton" class="button" type="button" data-short="高" disabled>适高</button>
+					<button id="rotateButton" class="button" type="button" data-short="转" disabled>旋转</button>
+					<button id="panButton" class="button" type="button" data-short="拖" data-pressed="false" disabled>拖动</button>
+					<button id="continuousButton" class="button" type="button" data-short="连" data-pressed="false" disabled>连续</button>
+					<button id="annotationButton" class="button" type="button" data-short="注" data-pressed="true">注解</button>
+				</div>
+				<div class="tool-group">
+					<button id="renderVectorButton" class="button" type="button" data-short="矢" data-pressed="true" disabled>矢量</button>
+					<button id="renderRasterButton" class="button" type="button" data-short="位" data-pressed="false" disabled>位图</button>
+				</div>
+				<div class="tool-group">
+					<label class="toolbar-select"><select id="exportFormat" class="format-select" title="导出格式" disabled></select><span id="formatValue"></span></label>
+					<label class="toolbar-select"><select id="imageDPI" class="format-select" title="输出精度" disabled>
+						<option value="96">96 dpi</option>
+						<option value="150">150 dpi</option>
+						<option value="300" selected>300 dpi</option>
+						<option value="600">600 dpi</option>
+					</select><span id="dpiValue">300</span></label>
+					<label class="toolbar-select"><select id="outputCompression" class="format-select" title="压缩模式" disabled><option value="0">原始</option><option value="1">无损</option><option value="2">轻压</option><option value="3">均衡</option><option value="4">强压</option></select><span id="compressionValue" data-short="原">原始</span></label>
+					<button id="exportPageButton" class="button" type="button" data-short="单" disabled>单页</button>
+					<button id="exportButton" class="button" type="button" data-short="多" disabled>文档</button>
+				</div>
 			</div>
+			<button id="refreshAppButton" class="button app-update" type="button" hidden>更新</button>
 		</header>
 		<div id="editorTools" class="editor-toolbar" hidden>
 			<div class="editor-group editor-actions">
@@ -708,7 +711,6 @@
 						<div id="appPanelTitle" class="panel-title compact">应用</div>
 						<div class="panel-actions">
 							<span id="offlineStatus" class="app-status">准备中</span>
-							<button id="refreshAppButton" class="small-button app-refresh" type="button" title="刷新应用" disabled>&#8635;</button>
 						</div>
 					</div>
 				</section>
diff --git a/assets/webui/ofdgo.css b/assets/webui/ofdgo.css
index a2fdd70..e959a10 100644
--- a/assets/webui/ofdgo.css
+++ b/assets/webui/ofdgo.css
@@ -445,6 +445,38 @@ a:focus-visible {
 	box-shadow: 0 1px 0 rgba(255, 255, 255, 0.68) inset;
 }
 
+.toolbar-frame {
+	display: flex;
+	min-width: 0;
+	background: var(--bar-bg);
+	border-bottom: 1px solid var(--line);
+}
+
+.toolbar-frame > .toolbar {
+	flex: 1 1 auto;
+	border-bottom: 0;
+}
+
+.app-update {
+	flex: 0 0 auto;
+	align-self: center;
+	width: 62px;
+	margin: 0 10px 0 0;
+	border-color: var(--accent);
+	background: #e4f3ef;
+	color: var(--accent-strong);
+	font-size: 14px;
+	line-height: 1;
+}
+
+.app-update:not(:disabled):hover {
+	background: #f2faf7;
+}
+
+.app-update[hidden] {
+	display: none;
+}
+
 .toolbar {
 	--tool-gap: 8px;
 	position: relative;
@@ -2281,14 +2313,6 @@ body[data-hide-meta] .meta-panel {
 	font-size: 12px;
 }
 
-.app-refresh {
-	width: 26px;
-	padding: 0;
-	color: var(--accent-strong);
-	font-size: 18px;
-	line-height: 1;
-}
-
 .navigation-tabs {
 	display: flex;
 	flex-shrink: 0;
diff --git a/assets/webui/ofdgo.js b/assets/webui/ofdgo.js
index 7d8206d..67de947 100644
--- a/assets/webui/ofdgo.js
+++ b/assets/webui/ofdgo.js
@@ -4194,16 +4194,18 @@ async function prepareOffline() {
 
 function watchApplicationUpdates(checksum) {
 	let checking = false;
+	let checked = 0;
 	async function check() {
-		if (checking || document.hidden || !navigator.onLine) {
+		if (checking || document.hidden || !navigator.onLine || Date.now() - checked < 60000) {
 			return;
 		}
 		checking = true;
+		checked = Date.now();
 		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";
+				el.refreshAppButton.hidden = latest === checksum;
 			}
 		} catch {
 		} finally {
@@ -4212,16 +4214,27 @@ function watchApplicationUpdates(checksum) {
 	}
 	window.addEventListener("online", check);
 	document.addEventListener("visibilitychange", check);
+	window.setInterval(check, 300000);
 	check();
 }
 
 function waitForWorker(worker, target) {
 	return new Promise((resolve, reject) => {
+		if (!worker) {
+			reject(new Error("离线服务未就绪"));
+			return;
+		}
+		const timer = setTimeout(() => {
+			worker.removeEventListener("statechange", changed);
+			reject(new Error("更新等待超时"));
+		}, 30000);
 		function changed() {
 			if (worker.state === target || worker.state === "activated") {
+				clearTimeout(timer);
 				worker.removeEventListener("statechange", changed);
 				resolve();
 			} else if (worker.state === "redundant") {
+				clearTimeout(timer);
 				worker.removeEventListener("statechange", changed);
 				reject(new Error("离线启动失败"));
 			}
@@ -4233,8 +4246,17 @@ function waitForWorker(worker, target) {
 
 function requestOffline(worker, type) {
 	return new Promise((resolve, reject) => {
+		if (!worker) {
+			reject(new Error("离线服务未就绪"));
+			return;
+		}
 		const channel = new MessageChannel();
+		const timer = setTimeout(() => {
+			close();
+			reject(new Error("更新等待超时"));
+		}, 180000);
 		function close() {
+			clearTimeout(timer);
 			channel.port1.close();
 			worker.removeEventListener("statechange", changed);
 		}
@@ -4253,13 +4275,23 @@ function requestOffline(worker, type) {
 			}
 		};
 		worker.addEventListener("statechange", changed);
-		worker.postMessage({ type }, [channel.port2]);
+		try {
+			worker.postMessage({ type }, [channel.port2]);
+		} catch (err) {
+			close();
+			channel.port2.close();
+			reject(err);
+		}
 		changed();
 	});
 }
 
 async function refreshApplication() {
-	if (document.body.hasAttribute("data-busy")) {
+	if (nativeHost || state.exporting || document.body.hasAttribute("data-busy")) {
+		return;
+	}
+	if (!navigator.onLine) {
+		setStatus("离线，联网后重试");
 		return;
 	}
 	const temporaryFonts = fontManager.userFonts.some((font) => font.source === "upload");
@@ -4267,21 +4299,29 @@ async function refreshApplication() {
 	if ((state.ofdBytes || state.doc || temporaryFonts) && !window.confirm(message)) {
 		return;
 	}
-	setBusy(true, "正在刷新应用", null, "正在刷新应用");
+	setBusy(true, "正在更新应用", null, "正在更新应用");
 	el.refreshAppButton.disabled = true;
-	const panels = document.querySelectorAll(".toolbar, .workspace");
+	el.refreshAppButton.textContent = "更新中";
+	const panels = document.querySelectorAll(".toolbar-frame, .workspace");
 	panels.forEach((panel) => { panel.inert = true; });
 	try {
 		if (navigator.storage?.persist) {
-			await navigator.storage.persist().catch(() => false);
+			navigator.storage.persist().catch(() => false);
 		}
 		const scope = new URL("./", location.href).href;
 		await navigator.locks.request(`ofdgo:${scope}:refresh`, { ifAvailable: true }, async (lock) => {
 			if (!lock) {
-				throw new Error("应用正在刷新");
+				throw new Error("其他页面正在更新");
 			}
 			const registration = await registerOffline();
-			await registration.update();
+			let timer;
+			try {
+				await Promise.race([registration.update(), new Promise((resolve, reject) => {
+					timer = setTimeout(() => reject(new Error("更新等待超时")), 30000);
+				})]);
+			} finally {
+				clearTimeout(timer);
+			}
 			if (registration.installing) {
 				await waitForWorker(registration.installing, "installed");
 			}
@@ -4292,10 +4332,11 @@ async function refreshApplication() {
 			location.reload();
 		});
 	} catch (err) {
-		setStatus(err.message === "应用正在刷新" ? err.message : "应用刷新失败");
+		setStatus(err.message === "其他页面正在更新" ? err.message : "更新失败，请重试");
 	} finally {
 		panels.forEach((panel) => { panel.inert = false; });
 		el.refreshAppButton.disabled = false;
+		el.refreshAppButton.textContent = "更新";
 		setBusy(false);
 	}
 }
@@ -12019,6 +12060,7 @@ function showError(err, empty = !state.doc) {
 
 function setBusy(busy, text = "", percent = 0, status = "") {
 	document.body.toggleAttribute("data-busy", busy);
+	el.refreshAppButton.disabled = busy;
 	updateStructureControls();
 	updateDocumentControls();
 	renderSecurity();
diff --git a/assets/webui/ofdgo_work.js b/assets/webui/ofdgo_work.js
index bf0e8cc..e953392 100644
--- a/assets/webui/ofdgo_work.js
+++ b/assets/webui/ofdgo_work.js
@@ -106,8 +106,9 @@ async function readResource(event, navigation) {
 }
 
 async function updateBundle(meta) {
+	const signal = AbortSignal.timeout(120000);
 	const resources = await Promise.all(ASSETS.map(async (url) => {
-		const response = await fetch(new Request(url, { cache: "no-store" }));
+		const response = await fetch(new Request(url, { cache: "no-store", signal }));
 		if (!response.ok || response.redirected) {
 			throw new Error("资源下载失败");
 		}