diff --git a/app/src/main/java/top/yeij/hearth/MainActivity.kt b/app/src/main/java/top/yeij/hearth/MainActivity.kt
index 9497918..1b9ffad 100644
--- a/app/src/main/java/top/yeij/hearth/MainActivity.kt
+++ b/app/src/main/java/top/yeij/hearth/MainActivity.kt
@@ -267,13 +267,16 @@ class MainActivity : Activity() {
         private val sidebarWidthPx by lazy {
             (SIDEBAR_WIDTH_DP * resources.displayMetrics.density).toInt()
         }
+        // 加载失败的 webapp id：Back 键时直接关闭而非 goBack 循环回退
+        // Failed webapp ids: on Back, close directly instead of looping goBack
+        private val failedWebViews = mutableSetOf<String>()
 
-        override fun openWebView(id: String, url: String) {
+        override fun openWebView(id: String, url: String, ua: String?) {
             if (contentWebViews.containsKey(id)) {
                 switchWebView(id)
                 return
             }
-            val webView = WebViewManager(this@MainActivity).createContentWebView()
+            val webView = WebViewManager(this@MainActivity).createContentWebView(ua)
             webView.webViewClient = object : WebViewClient() {
                 @Suppress("DEPRECATION", "OVERRIDE_DEPRECATION")
                 override fun onReceivedError(
@@ -283,6 +286,7 @@ class MainActivity : Activity() {
                     failingUrl: String?,
                 ) {
                     Log.d(TAG, "content onReceivedError: code=$code desc=$description url=$failingUrl")
+                    failedWebViews.add(id)
                     view?.loadDataWithBaseURL(null, errorPage(description ?: "未知错误"), "text/html", "utf-8", null)
                 }
             }
@@ -311,6 +315,7 @@ class MainActivity : Activity() {
 
         override fun closeWebView(id: String) {
             val webView = contentWebViews.remove(id) ?: return
+            failedWebViews.remove(id)
             root.removeView(webView)
             webView.stopLoading()
             webView.destroy()
@@ -333,8 +338,12 @@ class MainActivity : Activity() {
         }
 
         override fun goBack(): Boolean {
-            val webView = currentVisibleId?.let { contentWebViews[it] }
-            return if (webView != null && webView.canGoBack()) {
+            val id = currentVisibleId ?: return false
+            // 加载失败的 webapp：Back 直接关闭（返回 false 让 onBackPressed 关闭标签），
+            // 避免 goBack 回退到失败的 file:// 页面反复加载
+            if (failedWebViews.contains(id)) return false
+            val webView = contentWebViews[id] ?: return false
+            return if (webView.canGoBack()) {
                 webView.goBack()
                 true
             } else {
diff --git a/app/src/main/java/top/yeij/hearth/webapp/WebAppRepository.kt b/app/src/main/java/top/yeij/hearth/webapp/WebAppRepository.kt
index dc012e3..748e486 100644
--- a/app/src/main/java/top/yeij/hearth/webapp/WebAppRepository.kt
+++ b/app/src/main/java/top/yeij/hearth/webapp/WebAppRepository.kt
@@ -16,6 +16,7 @@ data class WebApp(
     val url: String,
     val offline: String? = null,
     val offlineVersion: String? = null,
+    val ua: String? = null,
 )
 
 // 网络抽象接口：Task 10 的 CardRepository 也会复用
@@ -106,12 +107,17 @@ class WebAppRepository(
             val offlineMap = map["offline"] as? Map<*, *>
             val offline = offlineMap?.get("package") as? String
             val offlineVersion = offlineMap?.get("version") as? String
+            // ua 可选：desktop/pc 用 PC UA，其他视为自定义 UA 字符串，不指定默认平板 UA
+            // ua optional: desktop/pc uses a desktop UA, others are custom UA strings,
+            // absent means the default tablet UA
+            val ua = map["ua"] as? String
             WebApp(
                 id, name,
                 resolvePath(icon),
                 resolvePath(url),
                 offline?.let { resolvePath(it) },
                 offlineVersion,
+                ua,
             )
         }
     }
diff --git a/app/src/main/java/top/yeij/hearth/webapp/WebAppStorage.kt b/app/src/main/java/top/yeij/hearth/webapp/WebAppStorage.kt
index 82e9c7f..f50c5fa 100644
--- a/app/src/main/java/top/yeij/hearth/webapp/WebAppStorage.kt
+++ b/app/src/main/java/top/yeij/hearth/webapp/WebAppStorage.kt
@@ -26,9 +26,21 @@ class WebAppStorage(private val context: Context) {
         File(appDir(id), "index.html").exists()
 
     // 本地离线包入口 URL（file:// 绝对路径），无则 null
-    // Local offline-package entry URL (file:// absolute path), null when absent
-    fun localIndexUrl(id: String): String? =
-        if (hasLocalPackage(id)) "file://" + File(appDir(id), "index.html").absolutePath else null
+    // canonicalPath 解析 /data/user/0 -> /data/data 符号链接，避免 WebView 的
+    // ERR_ACCESS_DENIED
+    // Local offline-package entry URL (file:// absolute path), null when absent.
+    // canonicalPath resolves the /data/user/0 -> /data/data symlink, avoiding the
+    // WebView ERR_ACCESS_DENIED
+    fun localIndexUrl(id: String): String? {
+        if (!hasLocalPackage(id)) return null
+        val f = File(appDir(id), "index.html")
+        val path = try {
+            f.canonicalPath
+        } catch (e: Exception) {
+            f.absolutePath
+        }
+        return "file://" + path
+    }
 
     // 本地离线包版本号（解压目录里的 .version 文件），无则 null
     // Local offline-package version (from the .version file), null when absent
diff --git a/app/src/main/java/top/yeij/hearth/webview/JsBridge.kt b/app/src/main/java/top/yeij/hearth/webview/JsBridge.kt
index b758a1d..4ed08e3 100644
--- a/app/src/main/java/top/yeij/hearth/webview/JsBridge.kt
+++ b/app/src/main/java/top/yeij/hearth/webview/JsBridge.kt
@@ -144,7 +144,7 @@ class JsBridge(
         // 1. 本地离线包优先（服务端删除后仍可用）
         val localUrl = st?.localIndexUrl(id)
         if (localUrl != null) {
-            openWebAppAt(container, host, id, localUrl, app.name)
+            openWebAppAt(container, host, id, localUrl, app.name, app.ua)
             return
         }
         // 2. 有离线包 → 后台下载解压（推送进度），完成后加载本地；失败回退远程
@@ -155,24 +155,24 @@ class JsBridge(
                 val fullUrl = resolveUrl(pkg)
                 st.downloadAndExtract(id, fullUrl, app.offlineVersion ?: "") { p -> pushWebappProgress(id, p) }
                 val url = st.localIndexUrl(id) ?: app.url
-                openWebAppAt(container, host, id, url, app.name)
+                openWebAppAt(container, host, id, url, app.name, app.ua)
                 pushWebappProgress(id, 100)
             }.start()
             return
         }
         // 3. 无离线包 → 远程加载（WebView 自带加载进度）
-        openWebAppAt(container, host, id, app.url, app.name)
+        openWebAppAt(container, host, id, app.url, app.name, app.ua)
     }
 
     // 在主线程打开指定 url 的 webAPP 标签
     // Open a webapp tab at the given url on the main thread
-    private fun openWebAppAt(container: WebAppContainer, host: WebAppHost, id: String, url: String, name: String) {
+    private fun openWebAppAt(container: WebAppContainer, host: WebAppHost, id: String, url: String, name: String, ua: String?) {
         onMain {
             container.open(id, url, name)
-            host.openWebView(id, url)
+            host.openWebView(id, url, ua)
             host.syncTabs(container.tabs())
         }
-        Log.d("HearthBridge", "openWebApp: id=$id url=$url")
+        Log.d("HearthBridge", "openWebApp: id=$id url=$url ua=$ua")
     }
 
     // 手动导入离线包（由 MainActivity 触发 SAF 选择 zip）
diff --git a/app/src/main/java/top/yeij/hearth/webview/WebAppHost.kt b/app/src/main/java/top/yeij/hearth/webview/WebAppHost.kt
index 43f8472..ec8cf31 100644
--- a/app/src/main/java/top/yeij/hearth/webview/WebAppHost.kt
+++ b/app/src/main/java/top/yeij/hearth/webview/WebAppHost.kt
@@ -8,9 +8,10 @@ import top.yeij.hearth.webapp.Tab
 // multi-WebView lifecycle, visibility, and navigation, and syncing tab state
 // back to the desktop H5 topbar
 interface WebAppHost {
-    // 创建内容 WebView 加载 url 并显示（已存在则切换到该标签）
-    // Create a content WebView loading url and show it (switch if already open)
-    fun openWebView(id: String, url: String)
+    // 创建内容 WebView 加载 url 并显示（已存在则切换到该标签）；ua 为清单声明的 UA
+    // Create a content WebView loading url and show it (switch if already open);
+    // ua is the UA declared in the manifest
+    fun openWebView(id: String, url: String, ua: String?)
 
     // 销毁对应内容 WebView
     // Destroy the corresponding content WebView
diff --git a/app/src/main/java/top/yeij/hearth/webview/WebViewManager.kt b/app/src/main/java/top/yeij/hearth/webview/WebViewManager.kt
index 0ee52c5..50eda8a 100644
--- a/app/src/main/java/top/yeij/hearth/webview/WebViewManager.kt
+++ b/app/src/main/java/top/yeij/hearth/webview/WebViewManager.kt
@@ -31,10 +31,18 @@ class WebViewManager(private val activity: Activity) {
     // (lifecycle is managed by the host); transparent background so a webapp without
     // a declared background shows the wallpaper instead of a default white
     @SuppressLint("SetJavaScriptEnabled")
-    fun createContentWebView(): WebView {
+    fun createContentWebView(ua: String?): WebView {
         val webView = WebView(activity)
         webView.setBackgroundColor(Color.TRANSPARENT)
         configure(webView)
+        // UA 解析：desktop/pc → PC UA；自定义字符串 → 直接用；null → 默认平板 UA
+        // UA resolution: desktop/pc -> desktop UA; custom string -> used as-is;
+        // null -> default tablet UA
+        webView.settings.userAgentString = when {
+            ua == null -> UA_TABLET
+            ua == "desktop" || ua == "pc" -> UA_DESKTOP
+            else -> ua
+        }
         return webView
     }
 
@@ -50,4 +58,15 @@ class WebViewManager(private val activity: Activity) {
             domStorageEnabled = true
         }
     }
+
+    companion object {
+        // PC 版 UA（desktop/pc）
+        private const val UA_DESKTOP =
+            "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 " +
+                "(KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"
+        // 安卓平板 UA（默认）
+        private const val UA_TABLET =
+            "Mozilla/5.0 (Linux; Android 13; SM-X700 Build/TP1A.220624.014) " +
+                "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"
+    }
 }