fix(browser): explain instead of crashing when the system WebView cannot start

app/src/main/java/com/yugahashimoto/andcode/feature/browser/GuestBrowserScreen.kt

@@ -1,11 +1,14 @@
 package com.yugahashimoto.andcode.feature.browser
 
 import android.annotation.SuppressLint
+import android.util.Log
+import android.view.View
 import android.view.ViewGroup
 import android.webkit.WebChromeClient
 import android.webkit.WebView
 import android.webkit.WebViewClient
 import androidx.activity.compose.BackHandler
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxSize
@@ -20,6 +23,7 @@ import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.LinearProgressIndicator
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.Text
@@ -31,14 +35,18 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clipToBounds
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.viewinterop.AndroidView
 import com.yugahashimoto.andcode.BuildConfig
 import com.yugahashimoto.andcode.R
 
+private const val TAG = "GuestBrowser"
+
 /** In-app browser for pages served inside the guest runtime (e.g. http://127.0.0.1:PORT/). */
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
@@ -51,6 +59,7 @@ fun GuestBrowserScreen(
     var canGoBack by remember { mutableStateOf(false) }
     var canGoForward by remember { mutableStateOf(false) }
     var webView by remember { mutableStateOf<WebView?>(null) }
+    var webViewUnavailable by remember { mutableStateOf(false) }
 
     BackHandler {
         val view = webView
@@ -74,48 +83,82 @@ fun GuestBrowserScreen(
         },
     ) { padding ->
         Column(modifier = Modifier.padding(padding).fillMaxSize()) {
-            GuestBrowserUrlBar(
-                urlInput = urlInput,
-                onUrlChange = { urlInput = it },
-                onGo = { webView?.loadUrl(normalizeUrl(urlInput)) },
-            )
+            if (!webViewUnavailable) {
+                GuestBrowserUrlBar(
+                    urlInput = urlInput,
+                    onUrlChange = { urlInput = it },
+                    onGo = { webView?.loadUrl(normalizeUrl(urlInput)) },
+                )
+            }
             if (progress in 1..99) {
                 LinearProgressIndicator(progress = { progress / 100f })
             }
-            AndroidView(
-                // WebView can draw its background outside its measured bounds, covering the URL
-                // field even while that field still accepts focus and keyboard input.
-                modifier = Modifier.weight(1f).clipToBounds(),
-                factory = { context ->
-                    // Lets the in-guest agent drive this WebView over CDP (the devtools abstract
-                    // socket is reachable from the guest, which shares the app's UID), so a page
-                    // can be shown to the user and operated by human and agent at the same time.
-                    WebView.setWebContentsDebuggingEnabled(BuildConfig.DEBUG)
-                    WebView(context).apply {
-                        layoutParams =
-                            ViewGroup.LayoutParams(
-                                ViewGroup.LayoutParams.MATCH_PARENT,
-                                ViewGroup.LayoutParams.MATCH_PARENT,
+            if (webViewUnavailable) {
+                WebViewUnavailableNotice(modifier = Modifier.weight(1f).fillMaxWidth())
+            } else {
+                AndroidView(
+                    // WebView can draw its background outside its measured bounds, covering the URL
+                    // field even while that field still accepts focus and keyboard input.
+                    modifier = Modifier.weight(1f).clipToBounds(),
+                    factory = { context ->
+                        // Only starting the system WebView provider can fail for reasons the app cannot
+                        // fix; everything after it runs on a WebView that exists, so a failure there is
+                        // a real bug and must not leave a half-built view behind.
+                        val created =
+                            viewOrNull(
+                                create = {
+                                    // Lets the in-guest agent drive this WebView over CDP (the devtools abstract
+                                    // socket is reachable from the guest, which shares the app's UID), so a page
+                                    // can be shown to the user and operated by human and agent at the same time.
+                                    WebView.setWebContentsDebuggingEnabled(BuildConfig.DEBUG)
+                                    WebView(context)
+                                },
+                                onFailure = { error -> Log.w(TAG, "The system WebView could not start", error) },
                             )
-                        configure(
-                            onProgress = { progress = it },
-                            onNavigationStateChange = { url, back, forward ->
-                                urlInput = url
-                                canGoBack = back
-                                canGoForward = forward
-                            },
-                        )
-                        webView = this
-                        if (initialUrl.isNotBlank()) {
-                            loadUrl(normalizeUrl(initialUrl))
+                        if (created == null) {
+                            webViewUnavailable = true
+                            View(context)
+                        } else {
+                            created.apply {
+                                layoutParams =
+                                    ViewGroup.LayoutParams(
+                                        ViewGroup.LayoutParams.MATCH_PARENT,
+                                        ViewGroup.LayoutParams.MATCH_PARENT,
+                                    )
+                                configure(
+                                    onProgress = { progress = it },
+                                    onNavigationStateChange = { url, back, forward ->
+                                        urlInput = url
+                                        canGoBack = back
+                                        canGoForward = forward
+                                    },
+                                )
+                                webView = this
+                                if (initialUrl.isNotBlank()) {
+                                    loadUrl(normalizeUrl(initialUrl))
+                                }
+                            }
                         }
-                    }
-                },
-            )
+                    },
+                )
+            }
         }
     }
 }
 
+/** Shown instead of the page when the system WebView cannot start, which the app cannot repair. */
+@Composable
+private fun WebViewUnavailableNotice(modifier: Modifier = Modifier) {
+    Box(modifier = modifier.padding(24.dp), contentAlignment = Alignment.Center) {
+        Text(
+            text = stringResource(R.string.guest_browser_webview_unavailable),
+            style = MaterialTheme.typography.bodyMedium,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            textAlign = TextAlign.Center,
+        )
+    }
+}
+
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 private fun GuestBrowserTopBar(

app/src/main/java/com/yugahashimoto/andcode/feature/browser/PlatformView.kt

@@ -0,0 +1,28 @@
+package com.yugahashimoto.andcode.feature.browser
+
+/**
+ * Builds a view the platform may refuse to build, returning null instead of throwing.
+ *
+ * WebView needs the system's WebView provider, and starting it can fail on a given device: on one
+ * vivo phone the provider's resource registration threw `Resources.NotFoundException`, which
+ * surfaced as an `AndroidRuntimeException` inside the Compose view factory and took the whole app
+ * down. A provider whose classes or native libraries cannot be loaded fails the same way as a
+ * [LinkageError]. Nothing the app does can repair either, so the caller shows an explanation instead.
+ *
+ * Only [Exception] and [LinkageError] are caught. Any other [Error], an [OutOfMemoryError] above
+ * all, is not a missing provider, and hiding it would leave the screen blaming WebView for a memory
+ * problem.
+ */
+internal fun <T : Any> viewOrNull(
+    create: () -> T,
+    onFailure: (Throwable) -> Unit = {},
+): T? =
+    try {
+        create()
+    } catch (error: Exception) {
+        onFailure(error)
+        null
+    } catch (error: LinkageError) {
+        onFailure(error)
+        null
+    }

app/src/main/res/values-ar/strings.xml

@@ -1219,6 +1219,7 @@
     <string name="guest_browser_back">رجوع</string>
     <string name="guest_browser_forward">تقدم</string>
     <string name="guest_browser_reload">إعادة تحميل</string>
+    <string name="guest_browser_webview_unavailable">يتعذّر تشغيل المتصفح الضيف لأن WebView لم يُحمَّل على هذا الجهاز. قد يحل تحديث Android System WebView أو إعادة تفعيله المشكلة.</string>
     <string name="setup_step_development_tools">أدوات التطوير</string>
     <string name="setup_development_tools_description">يتم تثبيت مكونات التشغيل الضرورية فقط افتراضيًا، ويمكنك إضافة مجموعة أدوات التطوير الكاملة.</string>
     <string name="setup_required_tools_description">سيتم دائمًا تثبيت Linux والوكلاء المحددين وGit وأدوات الدعم التي يستخدمها AndCode.</string>

app/src/main/res/values-es/strings.xml

@@ -1210,6 +1210,7 @@
     <string name="guest_browser_back">Atrás</string>
     <string name="guest_browser_forward">Avanzar</string>
     <string name="guest_browser_reload">Recargar</string>
+    <string name="guest_browser_webview_unavailable">El navegador invitado no puede iniciarse porque WebView no se pudo cargar en este dispositivo. Actualizar o volver a activar Android System WebView puede solucionarlo.</string>
     <string name="setup_step_development_tools">Herramientas de desarrollo</string>
     <string name="setup_development_tools_description">De forma predeterminada solo se instala lo necesario para ejecutar el entorno, o puedes incluir toda la cadena de desarrollo.</string>
     <string name="setup_required_tools_description">Linux, los agentes seleccionados, Git y las herramientas de soporte que usa AndCode. Siempre se instalan.</string>

app/src/main/res/values-fr/strings.xml

@@ -1210,6 +1210,7 @@
     <string name="guest_browser_back">Retour</string>
     <string name="guest_browser_forward">Avancer</string>
     <string name="guest_browser_reload">Recharger</string>
+    <string name="guest_browser_webview_unavailable">Le navigateur invité ne peut pas démarrer, car WebView n\'a pas pu se charger sur cet appareil. Mettre à jour ou réactiver Android System WebView peut résoudre le problème.</string>
     <string name="setup_step_development_tools">Outils de développement</string>
     <string name="setup_development_tools_description">Installe uniquement le nécessaire par défaut, ou incluez la chaîne complète d’outils.</string>
     <string name="setup_required_tools_description">Linux, les agents sélectionnés, Git et les outils requis par AndCode. Ils sont toujours installés.</string>

app/src/main/res/values-ja/strings.xml

@@ -1224,6 +1224,7 @@
     <string name="guest_browser_back">戻る</string>
     <string name="guest_browser_forward">進む</string>
     <string name="guest_browser_reload">再読み込み</string>
+    <string name="guest_browser_webview_unavailable">この端末の WebView を読み込めないため、ゲストブラウザを開けません。Android System WebView を更新するか、有効にし直すと解決する場合があります。</string>
     <string name="setup_step_development_tools">開発ツール</string>
     <string name="setup_development_tools_description">既定では実行に必要なものだけをインストールします。完全な開発ツールチェーンも選択できます。</string>
     <string name="setup_required_tools_description">Linux、選択したエージェント、Git、および AndCode が使用するサポートツールです。これらは常にインストールされます。</string>

app/src/main/res/values-pt-rBR/strings.xml

@@ -1210,6 +1210,7 @@
     <string name="guest_browser_back">Voltar</string>
     <string name="guest_browser_forward">Avançar</string>
     <string name="guest_browser_reload">Recarregar</string>
+    <string name="guest_browser_webview_unavailable">O navegador convidado não pode ser iniciado porque o WebView não foi carregado neste dispositivo. Atualizar ou reativar o Android System WebView pode resolver o problema.</string>
     <string name="setup_step_development_tools">Ferramentas de desenvolvimento</string>
     <string name="setup_development_tools_description">Por padrão, instale apenas o necessário para executar, ou inclua a cadeia completa de desenvolvimento.</string>
     <string name="setup_required_tools_description">Linux, os agentes selecionados, Git e as ferramentas de suporte usadas pelo AndCode. São sempre instalados.</string>

app/src/main/res/values-ru/strings.xml

@@ -1213,6 +1213,7 @@
     <string name="guest_browser_back">Назад</string>
     <string name="guest_browser_forward">Вперёд</string>
     <string name="guest_browser_reload">Обновить</string>
+    <string name="guest_browser_webview_unavailable">Гостевой браузер не запускается: на этом устройстве не удалось загрузить WebView. Обновление или повторное включение Android System WebView может помочь.</string>
     <string name="setup_step_development_tools">Инструменты разработки</string>
     <string name="setup_development_tools_description">По умолчанию устанавливаются только необходимые компоненты. При желании можно добавить полный набор инструментов.</string>
     <string name="setup_required_tools_description">Linux, выбранные агенты, Git и вспомогательные инструменты AndCode. Они устанавливаются всегда.</string>

app/src/main/res/values-zh-rCN/strings.xml

@@ -1204,6 +1204,7 @@
     <string name="guest_browser_back">后退</string>
     <string name="guest_browser_forward">前进</string>
     <string name="guest_browser_reload">重新加载</string>
+    <string name="guest_browser_webview_unavailable">无法启动访客浏览器，因为此设备上的 WebView 加载失败。更新或重新启用 Android System WebView 可能会解决此问题。</string>
     <string name="setup_step_development_tools">开发工具</string>
     <string name="setup_development_tools_description">默认只安装运行所需组件，也可以一并安装完整开发工具链。</string>
     <string name="setup_required_tools_description">Linux、所选智能体、Git 以及 AndCode 功能依赖的支持工具，将始终安装。</string>

app/src/main/res/values/strings.xml

@@ -1229,6 +1229,7 @@
     <string name="guest_browser_back">Back</string>
     <string name="guest_browser_forward">Forward</string>
     <string name="guest_browser_reload">Reload</string>
+    <string name="guest_browser_webview_unavailable">The Guest Browser cannot start because the WebView on this device failed to load. Updating or re-enabling Android System WebView may fix this.</string>
     <string name="setup_step_development_tools">Development tools</string>
     <string name="setup_development_tools_description">Install only the runtime by default, or include the complete development toolchain.</string>
     <string name="setup_required_tools_description">Linux, the selected agents, Git, and the support tools used by AndCode. These are always installed.</string>

app/src/test/java/com/yugahashimoto/andcode/feature/browser/PlatformViewTest.kt

@@ -0,0 +1,51 @@
+package com.yugahashimoto.andcode.feature.browser
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertSame
+import org.junit.Assert.assertThrows
+import org.junit.Test
+
+class PlatformViewTest {
+    @Test
+    fun `returns the view when the platform builds it`() {
+        val view = Any()
+
+        assertSame(view, viewOrNull(create = { view }))
+    }
+
+    @Test
+    fun `returns null and reports the cause when the platform refuses to build the view`() {
+        // The WebView provider's resource registration failed on a vivo device and surfaced as a
+        // RuntimeException wrapping a Resources.NotFoundException.
+        val refusal = RuntimeException("failed to redirect ResourcesImpl", IllegalStateException("not found"))
+        val reported = mutableListOf<Throwable>()
+
+        val view = viewOrNull<Any>(create = { throw refusal }, onFailure = { reported += it })
+
+        assertNull(view)
+        assertEquals(listOf<Throwable>(refusal), reported)
+    }
+
+    @Test
+    fun `a provider whose native code fails to load is also a missing view`() {
+        // The provider's classes and libraries can fail to load, which arrives as a LinkageError.
+        val reported = mutableListOf<Throwable>()
+
+        val view =
+            viewOrNull<Any>(
+                create = { throw UnsatisfiedLinkError("libwebviewchromium.so") },
+                onFailure = { reported += it },
+            )
+
+        assertNull(view)
+        assertEquals(1, reported.size)
+    }
+
+    @Test
+    fun `does not hide an error that is not a missing view`() {
+        assertThrows(OutOfMemoryError::class.java) {
+            viewOrNull<Any>(create = { throw OutOfMemoryError() })
+        }
+    }
+}