feat: refine AI navigation and accessibility recovery

frontend/lib/shared/services/screenshot_channel.dart

@@ -62,9 +62,39 @@ class RecognitionDiagnostic {
   }
 }
 
+enum AccessibilityConnectionState {
+  unauthorized,
+  reconnecting,
+  connected,
+  disconnected;
+
+  static AccessibilityConnectionState parse(
+    Object? value, {
+    required bool authorized,
+    required bool connected,
+  }) {
+    return switch (value?.toString()) {
+      'reconnecting' => AccessibilityConnectionState.reconnecting,
+      'connected' => AccessibilityConnectionState.connected,
+      'disconnected' => AccessibilityConnectionState.disconnected,
+      'unauthorized' => AccessibilityConnectionState.unauthorized,
+      _ =>
+        !authorized
+            ? unauthorized
+            : connected
+            ? AccessibilityConnectionState.connected
+            : disconnected,
+    };
+  }
+}
+
 class RecognitionStatus {
   final bool accessibilityAuthorized;
   final bool accessibilityConnected;
+  final AccessibilityConnectionState accessibilityConnectionState;
+  final DateTime? accessibilityLastConnectedAt;
+  final DateTime? accessibilityLastDisconnectedAt;
+  final DateTime? recognitionProcessStartedAt;
   final bool notificationAuthorized;
   final bool notificationConnected;
   final bool postNotificationsGranted;
@@ -81,6 +111,11 @@ class RecognitionStatus {
   const RecognitionStatus({
     required this.accessibilityAuthorized,
     required this.accessibilityConnected,
+    this.accessibilityConnectionState =
+        AccessibilityConnectionState.unauthorized,
+    this.accessibilityLastConnectedAt,
+    this.accessibilityLastDisconnectedAt,
+    this.recognitionProcessStartedAt,
     required this.notificationAuthorized,
     required this.notificationConnected,
     required this.postNotificationsGranted,
@@ -101,10 +136,28 @@ class RecognitionStatus {
     final settings = rawSettings == null || rawSettings.isEmpty
         ? const <String, dynamic>{}
         : jsonDecode(rawSettings) as Map<String, dynamic>;
+    final accessibilityAuthorized =
+        value['accessibilityAuthorized'] as bool? ?? false;
+    final accessibilityConnected =
+        value['accessibilityConnected'] as bool? ?? false;
+    DateTime? epochDate(String key) {
+      final epoch = (value[key] as num?)?.toInt() ?? 0;
+      return epoch <= 0 ? null : DateTime.fromMillisecondsSinceEpoch(epoch);
+    }
+
     return RecognitionStatus(
-      accessibilityAuthorized:
-          value['accessibilityAuthorized'] as bool? ?? false,
-      accessibilityConnected: value['accessibilityConnected'] as bool? ?? false,
+      accessibilityAuthorized: accessibilityAuthorized,
+      accessibilityConnected: accessibilityConnected,
+      accessibilityConnectionState: AccessibilityConnectionState.parse(
+        value['accessibilityConnectionState'],
+        authorized: accessibilityAuthorized,
+        connected: accessibilityConnected,
+      ),
+      accessibilityLastConnectedAt: epochDate('accessibilityLastConnectedAt'),
+      accessibilityLastDisconnectedAt: epochDate(
+        'accessibilityLastDisconnectedAt',
+      ),
+      recognitionProcessStartedAt: epochDate('recognitionProcessStartedAt'),
       notificationAuthorized: value['notificationAuthorized'] as bool? ?? false,
       notificationConnected: value['notificationConnected'] as bool? ?? false,
       postNotificationsGranted:
@@ -130,6 +183,19 @@ class RecognitionStatus {
             ),
     );
   }
+
+  bool get accessibilityNeedsRecovery =>
+      accessibilityAuthorized &&
+      !accessibilityConnected &&
+      accessibilityConnectionState == AccessibilityConnectionState.disconnected;
+
+  String get accessibilityConnectionLabel =>
+      switch (accessibilityConnectionState) {
+        AccessibilityConnectionState.unauthorized => '未授权',
+        AccessibilityConnectionState.reconnecting => '正在重连',
+        AccessibilityConnectionState.connected => '已连接',
+        AccessibilityConnectionState.disconnected => '服务未连接',
+      };
 }
 
 class RecognitionCandidate {
@@ -403,6 +469,31 @@ class ScreenshotChannel {
     }
   }
 
+  static Future<RecognitionStatus> waitForAccessibilityConnection({
+    Duration timeout = const Duration(seconds: 5),
+    Duration interval = const Duration(milliseconds: 500),
+  }) async {
+    var status = await recognitionStatus();
+    final recognitionEnabled =
+        status.accessibilityEvents || status.aiScreenshot;
+    if (!recognitionEnabled ||
+        !status.accessibilityAuthorized ||
+        status.accessibilityConnected) {
+      return status;
+    }
+    final deadline = DateTime.now().add(timeout);
+    while (DateTime.now().isBefore(deadline)) {
+      await Future<void>.delayed(interval);
+      status = await recognitionStatus();
+      if (!status.accessibilityAuthorized ||
+          status.accessibilityConnected ||
+          !(status.accessibilityEvents || status.aiScreenshot)) {
+        return status;
+      }
+    }
+    return status;
+  }
+
   static Future<bool> clearRecognitionDiagnostic() async {
     try {
       return await _channel.invokeMethod<bool>('clearRecognitionDiagnostic') ??

frontend/lib/shared/widgets/ai_access_gate.dart

@@ -6,12 +6,13 @@ import 'package:miaoji_zhang/shared/theme/app_theme.dart';
 import 'package:miaoji_zhang/shared/widgets/app_controls.dart';
 import 'package:miaoji_zhang/shared/widgets/app_icons.dart';
 
-enum AiAccessState { guest, reauthenticate, cloudDisabled }
+enum AiAccessState { guest, reauthenticate, aiDisabled, cloudDisabled }
 
 AiAccessState? currentAiAccessState() {
   final session = SessionStore.instance;
   if (session.isGuest) return AiAccessState.guest;
   if (session.needsReauth) return AiAccessState.reauthenticate;
+  if (!session.aiEnabled) return AiAccessState.aiDisabled;
   if (!session.cloudSyncEnabled) return AiAccessState.cloudDisabled;
   return null;
 }
@@ -32,23 +33,27 @@ class _AiAccessGateState extends State<AiAccessGate> {
   String get _title => switch (widget.state) {
     AiAccessState.guest => '登录后使用 AI 助手',
     AiAccessState.reauthenticate => '登录状态已过期',
+    AiAccessState.aiDisabled => 'AI 功能已关闭',
     AiAccessState.cloudDisabled => 'AI 功能需要云连接',
   };
 
   String get _message => switch (widget.state) {
     AiAccessState.guest => '游客账单会继续安全保存在本机。登录后即可使用 AI 聊天、语音解析和图片识别。',
     AiAccessState.reauthenticate => '本地记账不受影响。重新登录后可以继续使用 AI 和云同步。',
+    AiAccessState.aiDisabled => '当前账号暂未开通 AI，手动记账和统计不受影响。',
     AiAccessState.cloudDisabled => '当前账号仅使用本地数据。开启云同步后才能发送 AI 消息。',
   };
 
-  String get _actionLabel => switch (widget.state) {
+  String? get _actionLabel => switch (widget.state) {
     AiAccessState.guest => '登录后使用',
     AiAccessState.reauthenticate => '重新登录',
+    AiAccessState.aiDisabled => null,
     AiAccessState.cloudDisabled => '开启云同步',
   };
 
   Future<void> _act() async {
     if (_busy) return;
+    if (widget.state == AiAccessState.aiDisabled) return;
     if (widget.onAction != null) {
       await widget.onAction!();
       return;
@@ -115,15 +120,17 @@ class _AiAccessGateState extends State<AiAccessGate> {
                       height: 1.6,
                     ),
                   ),
-                  SizedBox(height: 22),
-                  SizedBox(
-                    width: double.infinity,
-                    child: JzActionButton(
-                      label: _actionLabel,
-                      loading: _busy,
-                      onPressed: _busy ? null : _act,
+                  if (_actionLabel case final label?) ...[
+                    SizedBox(height: 22),
+                    SizedBox(
+                      width: double.infinity,
+                      child: JzActionButton(
+                        label: label,
+                        loading: _busy,
+                        onPressed: _busy ? null : _act,
+                      ),
                     ),
-                  ),
+                  ],
                   if (widget.state == AiAccessState.guest) ...[
                     SizedBox(height: 12),
                     Text(