fix: harden Android background runtime against platform channel failures

Author: mxnix

lib/core/platform/android_foreground_runtime.dart

@@ -87,28 +87,37 @@ class AndroidForegroundRuntime {
       return;
     }
 
-    final l10n = lookupKickLocalizations();
-    await ensurePermissions();
-    if (await FlutterForegroundTask.checkNotificationPermission() !=
-        NotificationPermission.granted) {
-      return;
-    }
-    await _setNotificationState(mode: _notificationModeProxy);
-    if (await isRunning()) {
-      await FlutterForegroundTask.updateService(
+    try {
+      final l10n = lookupKickLocalizations();
+      await ensurePermissions();
+      if (await FlutterForegroundTask.checkNotificationPermission() !=
+          NotificationPermission.granted) {
+        return;
+      }
+      await _setNotificationState(mode: _notificationModeProxy);
+      if (await isRunning()) {
+        await FlutterForegroundTask.updateService(
+          notificationTitle: l10n.runtimeNotificationTitle,
+          notificationText: l10n.runtimeNotificationReturn,
+        );
+        return;
+      }
+
+      await FlutterForegroundTask.startService(
+        serviceId: 701,
         notificationTitle: l10n.runtimeNotificationTitle,
-        notificationText: l10n.runtimeNotificationReturn,
+        notificationText: l10n.runtimeNotificationManage,
+        notificationInitialRoute: '/home',
+        callback: startForegroundRuntimeCallback,
       );
-      return;
+    } on PlatformException {
+      // Platform channel may not be available if the engine is still
+      // recovering after a background/foreground transition. The proxy can
+      // continue without the foreground service — it will be retried on the
+      // next start cycle.
+    } on StateError {
+      // BackgroundIsolateBinaryMessenger may not be ready yet.
     }
-
-    await FlutterForegroundTask.startService(
-      serviceId: 701,
-      notificationTitle: l10n.runtimeNotificationTitle,
-      notificationText: l10n.runtimeNotificationManage,
-      notificationInitialRoute: '/home',
-      callback: startForegroundRuntimeCallback,
-    );
   }
 
   static Future<bool> ensureTemporaryRunning({String? notificationTitle}) async {
@@ -162,11 +171,17 @@ class AndroidForegroundRuntime {
       return;
     }
 
-    if (await isRunning()) {
-      await FlutterForegroundTask.stopService();
+    try {
+      if (await isRunning()) {
+        await FlutterForegroundTask.stopService();
+      }
+      await FlutterForegroundTask.removeData(key: _notificationModeStorageKey);
+      await FlutterForegroundTask.removeData(key: _notificationTitleStorageKey);
+    } on PlatformException {
+      // Platform channel may be unavailable during background transitions.
+    } on StateError {
+      // BackgroundIsolateBinaryMessenger may not be ready.
     }
-    await FlutterForegroundTask.removeData(key: _notificationModeStorageKey);
-    await FlutterForegroundTask.removeData(key: _notificationTitleStorageKey);
   }
 
   static Future<void> _setNotificationState({

lib/proxy/engine/proxy_controller.dart

@@ -29,9 +29,11 @@ typedef AndroidRuntimeRunningCheck = Future<bool> Function();
 typedef AndroidRuntimeEffect = Future<void> Function();
 typedef AndroidLocalNetworkPermissionRequest = Future<bool> Function();
 
-/// Short grace period after stopping the Android foreground runtime before the
+/// Grace period after stopping the Android foreground runtime before the
 /// isolate binds a new socket. Gives the OS time to release the previous port.
-const _androidRuntimeStopGracePeriod = Duration(milliseconds: 250);
+/// Android may take longer to release sockets when transitioning between
+/// foreground and background states, so this needs to be generous.
+const _androidRuntimeStopGracePeriod = Duration(milliseconds: 800);
 
 class ProxyRuntimeState {
   const ProxyRuntimeState({

lib/proxy/engine/proxy_isolate.dart

@@ -26,9 +26,10 @@ import 'proxy_cors.dart';
 
 const _maxRequestBodyBytes = 20 * 1024 * 1024;
 const _proxyBindRetryDelays = <Duration>[
-  Duration(milliseconds: 100),
   Duration(milliseconds: 200),
-  Duration(milliseconds: 400),
+  Duration(milliseconds: 500),
+  Duration(milliseconds: 1000),
+  Duration(milliseconds: 2000),
 ];
 const _modelCatalogRefreshInterval = Duration(minutes: 30);
 const defaultProxyRuntimeHost = '127.0.0.1';