fix(routing): 堵住 ip_cidr direct 旁路系统层 + 客户端保存失败可见提示

分支审核发现两处 Important,合并前修复。

① [安全] direct 的 ip_cidr 用户规则可自伤式旁路整条隧道:
   Validate 原先只校 CIDR 语法。用户提交 ip_cidr=0.0.0.0/0 action=direct
   (或 172.16.0.0/12,含隧道 DNS 172.19.0.2)会并入 TUN 入站
   route_exclude_address(OS/auto_route 层,位于系统强制层之下),被排除的
   流量根本不进 sing-box → hijack-dns 与整条隧道被静默旁路,违反「系统层
   用户不可越」铁律。
   - Validate: direct 的 ip_cidr 拒绝 catch-all(/0)及与保留段 172.16.0.0/12
     重叠(写入闸)。
   - clientconfig 渲染层:新增 routing.SafeToExclude 守卫,只有安全的 direct
     ip_cidr 才并入 route_exclude_address(纵深防护,兜底写入闸之前的历史坏行)。
   - 测试 TestValidateDirectIPCIDRReservedGuard 钉死:拒 catch-all/隧道段重叠、
     放行 proxy catch-all 与不重叠 direct。

② [健壮性] 客户端保存失败静默回滚 + 抛未捕获异步异常 + 对话框无字段校验:
   _persist 失败会 rethrow(约定调用方 catch),但屏幕层所有回调
   (setMode/setBuiltin/addRule/removeRule/reorder/resetToDefault)均未 catch,
   规则闪现即消失、无提示,且 rethrow 变 zone 未处理异常。
   - 新增 _guardSave 守卫:await + 失败弹 SnackBar(AuthApiException 显服务端
     双语文案含校验错,其余回退通用「保存失败」),包裹全部变更类回调。
   - 添加规则对话框:_valueError 字段级预校验(ip_cidr 用 InternetAddress
     校验、geo 白名单仅 cn),非法即禁用保存并内联红字提示;语义级(保留段)
     仍由服务端权威判定经 SnackBar 呈现。
   - l10n 单源新增 routingSaveFailed / routingRuleValueInvalid(6 语),regen。

go test ./... 全绿;flutter analyze 无 error;flutter test 265 全过无 golden 回归;
codegen 幂等、原型 i18n 无漂移。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A79VtQA1BwTuQN1ThpvYpo

client/lib/l10n/app_text.dart

@@ -663,6 +663,8 @@ abstract class AppText {
   String get routingRuleValueHint;   // 目标输入框占位 / Target input placeholder
   String get routingNoRules;         // 暂无自定义规则 / No custom rules yet
   String get routingAddRule;         // 添加规则 / Add rule
+  String get routingSaveFailed;      // 保存失败,请重试 / Save failed, please try again
+  String get routingRuleValueInvalid; // 格式不正确 / Invalid format
   String get routingImport;          // 从文本导入 / Import from text
   String get routingReset;           // 重置默认 / Reset defaults
   String get routingResetConfirmTitle;  // 重置为默认规则? / Reset to defaults?

client/lib/l10n/strings_en.dart

@@ -571,6 +571,10 @@ class StringsEn extends AppText {
   @override
   String get routingAddRule => 'Add rule';
   @override
+  String get routingSaveFailed => 'Save failed, please try again';
+  @override
+  String get routingRuleValueInvalid => 'Invalid format';
+  @override
   String get routingImport => 'Import from text';
   @override
   String get routingReset => 'Reset defaults';

client/lib/l10n/strings_es.dart

@@ -571,6 +571,10 @@ class StringsEs extends AppText {
   @override
   String get routingAddRule => 'Añadir regla';
   @override
+  String get routingSaveFailed => 'Error al guardar, inténtalo de nuevo';
+  @override
+  String get routingRuleValueInvalid => 'Formato no válido';
+  @override
   String get routingImport => 'Importar desde texto';
   @override
   String get routingReset => 'Restablecer';

client/lib/l10n/strings_ja.dart

@@ -571,6 +571,10 @@ class StringsJa extends AppText {
   @override
   String get routingAddRule => 'ルールを追加';
   @override
+  String get routingSaveFailed => '保存に失敗しました。もう一度お試しください';
+  @override
+  String get routingRuleValueInvalid => '形式が正しくありません';
+  @override
   String get routingImport => 'テキストから読み込み';
   @override
   String get routingReset => 'デフォルトに戻す';

client/lib/l10n/strings_ko.dart

@@ -571,6 +571,10 @@ class StringsKo extends AppText {
   @override
   String get routingAddRule => '규칙 추가';
   @override
+  String get routingSaveFailed => '저장에 실패했습니다. 다시 시도하세요';
+  @override
+  String get routingRuleValueInvalid => '형식이 올바르지 않습니다';
+  @override
   String get routingImport => '텍스트에서 가져오기';
   @override
   String get routingReset => '기본값 재설정';

client/lib/l10n/strings_ru.dart

@@ -571,6 +571,10 @@ class StringsRu extends AppText {
   @override
   String get routingAddRule => 'Добавить правило';
   @override
+  String get routingSaveFailed => 'Не удалось сохранить, попробуйте ещё раз';
+  @override
+  String get routingRuleValueInvalid => 'Неверный формат';
+  @override
   String get routingImport => 'Импорт из текста';
   @override
   String get routingReset => 'Сбросить настройки';

client/lib/l10n/strings_zh.dart

@@ -571,6 +571,10 @@ class StringsZh extends AppText {
   @override
   String get routingAddRule => '添加规则';
   @override
+  String get routingSaveFailed => '保存失败,请重试';
+  @override
+  String get routingRuleValueInvalid => '格式不正确';
+  @override
   String get routingImport => '从文本导入';
   @override
   String get routingReset => '重置默认';

client/lib/widgets/routing_screen.dart

@@ -13,12 +13,15 @@
 //    - 域名类规则(domain/domain_suffix/domain_keyword)命中 RoutingProfile.
 //      systemLockedDomains(FT-A 起 GET /v1/me/routing 下发的私有服务域名清单,
 //      PANGOLIN_PRIVATE_SPLIT_DOMAINS)——服务端渲染时恒强制走隧道,与用户规则动作冲突。
+import 'dart:io' show InternetAddress, InternetAddressType;
+
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../l10n/app_text.dart';
 import '../models/routing_profile.dart';
 import '../pangolin_theme.dart';
+import '../services/auth_api.dart' show AuthApiException;
 import '../state/app_providers.dart';
 import '../state/routing_provider.dart';
 import 'pangolin_button.dart';
@@ -61,6 +64,25 @@ class RoutingScreen extends ConsumerWidget {
   }
 }
 
+/// 变更类操作统一守卫:await + 失败弹 SnackBar(不再静默回滚 / 抛未捕获异步异常)。
+/// _persist 失败已回滚 state 并 rethrow,这里兜住并把原因告知用户;AuthApiException
+/// 带服务端双语文案(含 routing_invalid 校验错误),其余异常回退通用「保存失败」。
+Future<void> _guardSave(BuildContext context, AppText t, Future<void> Function() op) async {
+  try {
+    await op();
+  } on AuthApiException catch (e) {
+    if (!context.mounted) return;
+    _showRoutingError(context, t.lang == AppLang.zh ? e.messageZh : e.messageEn);
+  } catch (_) {
+    if (!context.mounted) return;
+    _showRoutingError(context, t.routingSaveFailed);
+  }
+}
+
+void _showRoutingError(BuildContext context, String msg) {
+  ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(msg)));
+}
+
 class _RoutingBody extends ConsumerWidget {
   const _RoutingBody({required this.t, required this.profile});
   final AppText t;
@@ -86,7 +108,7 @@ class _RoutingBody extends ConsumerWidget {
             (icon: PangolinIcons.arrowRight, label: t.routingModeDirect),
           ],
           selectedIndex: selectedIdx,
-          onChanged: (i) => notifier.setMode(_kModeValues[i]),
+          onChanged: (i) => _guardSave(context, t, () => notifier.setMode(_kModeValues[i])),
         ),
         const SizedBox(height: 8),
         Text(t.routingModeNote, style: PangolinText.caption.copyWith(color: c.fg3, height: 1.5)),
@@ -101,7 +123,7 @@ class _RoutingBody extends ConsumerWidget {
             title: t.routingCnDirect,
             sub: 'GeoIP / GeoSite CN',
             value: profile.builtin.chinaDirect,
-            onChanged: (v) => notifier.setBuiltin(profile.builtin.copyWith(chinaDirect: v)),
+            onChanged: (v) => _guardSave(context, t, () => notifier.setBuiltin(profile.builtin.copyWith(chinaDirect: v))),
             last: false,
           ),
           _forcedRow(c, icon: PangolinIcons.home, title: t.routingLanDirect, sub: t.routingLanForced, pill: t.routingForcedPill),
@@ -135,14 +157,14 @@ class _RoutingBody extends ConsumerWidget {
                     shrinkWrap: true,
                     physics: const NeverScrollableScrollPhysics(),
                     buildDefaultDragHandles: false,
-                    onReorder: (oldIndex, newIndex) => notifier.reorder(oldIndex, newIndex),
+                    onReorder: (oldIndex, newIndex) => _guardSave(context, t, () => notifier.reorder(oldIndex, newIndex)),
                     children: [
                       for (var i = 0; i < profile.rules.length; i++)
                         _ruleRow(
                             context, c, t, i, profile.rules[i],
                             _conflictFor(profile.rules, i, profile.systemLockedDomains),
                             i < profile.rules.length - 1,
-                            onDelete: () => notifier.removeRule(i)),
+                            onDelete: () => _guardSave(context, t, () => notifier.removeRule(i))),
                     ],
                   ),
                 ),
@@ -220,13 +242,15 @@ class _RoutingBody extends ConsumerWidget {
       ),
     );
     if (ok != true) return;
-    await ref.read(routingProfileProvider.notifier).resetToDefault();
+    if (!context.mounted) return;
+    await _guardSave(context, t, () => ref.read(routingProfileProvider.notifier).resetToDefault());
   }
 
   Future<void> _openAddDialog(BuildContext context, WidgetRef ref, AppText t) async {
     final rule = await showDialog<RoutingRule>(context: context, builder: (_) => _AddRuleDialog(t: t));
     if (rule == null) return;
-    await ref.read(routingProfileProvider.notifier).addRule(rule);
+    if (!context.mounted) return;
+    await _guardSave(context, t, () => ref.read(routingProfileProvider.notifier).addRule(rule));
   }
 
   Widget _builtinToggleRow(
@@ -446,11 +470,38 @@ class _AddRuleDialogState extends State<_AddRuleDialog> {
     super.dispose();
   }
 
+  /// 字段级预校验:只拦明显格式错(空由按钮禁用兜底),避免"乐观显示→服务端 400→静默消失"。
+  /// 语义级(保留段/catch-all direct)仍由服务端权威判定,经 SnackBar 呈现。返回 null=通过。
+  String? _valueError(AppText t) {
+    final v = _value.text.trim();
+    if (v.isEmpty) return null;
+    switch (_type) {
+      case 'ip_cidr':
+        if (!_isValidCidr(v)) return t.routingRuleValueInvalid;
+      case 'geoip':
+      case 'geosite':
+        if (v.toLowerCase() != 'cn') return t.routingRuleValueInvalid; // geo 白名单仅 cn
+    }
+    return null;
+  }
+
+  bool _isValidCidr(String s) {
+    final parts = s.split('/');
+    if (parts.length != 2) return false;
+    final prefix = int.tryParse(parts[1]);
+    if (prefix == null) return false;
+    final addr = InternetAddress.tryParse(parts[0]);
+    if (addr == null) return false;
+    final max = addr.type == InternetAddressType.IPv6 ? 128 : 32;
+    return prefix >= 0 && prefix <= max;
+  }
+
   @override
   Widget build(BuildContext context) {
     final c = context.pangolin;
     final t = widget.t;
-    final canSave = _value.text.trim().isNotEmpty;
+    final valueError = _valueError(t);
+    final canSave = _value.text.trim().isNotEmpty && valueError == null;
 
     return AlertDialog(
       backgroundColor: c.surface,
@@ -479,6 +530,11 @@ class _AddRuleDialogState extends State<_AddRuleDialog> {
               onChanged: (_) => setState(() {}),
             ),
           ),
+          if (valueError != null)
+            Padding(
+              padding: const EdgeInsets.only(top: 6, left: 4),
+              child: Text(valueError, style: PangolinText.caption.copyWith(color: c.danger)),
+            ),
           const SizedBox(height: 14),
           SegSwitch(
             options: [