fix(client/orders): 继续支付改为 retry 恢复原单会话(原误进购买页致重复下单);409 已付自纠刷新

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P9G7E3wmAYL9KeYCVZVsqu

client/test/unit/payment_flow_test.dart

@@ -7,10 +7,11 @@ import 'package:pangolin_vpn/state/payment_provider.dart';
 
 class _FakePaymentApi implements PaymentApi {
   _FakePaymentApi();
-  int createCalls = 0, cancelCalls = 0, statusCalls = 0;
+  int createCalls = 0, cancelCalls = 0, statusCalls = 0, retryCalls = 0;
   bool activated = false;
   Exception? retryError;
   String lastMethod = '';
+  String lastOrderNo = '';
 
   @override
   Future<List<PayCatalogItem>> catalog() async => const [];
@@ -35,6 +36,9 @@ class _FakePaymentApi implements PaymentApi {
 
   @override
   Future<PayOrder> retry(String orderNo, {required String method, Map<String, String>? metadata}) async {
+    retryCalls++;
+    lastMethod = method;
+    lastOrderNo = orderNo;
     if (retryError != null) throw retryError!;
     return PayOrder(orderNo: orderNo, session: PaySession(renderType: 'redirect', payload: const {'url': 'https://y'}, expiresAt: null));
   }
@@ -100,4 +104,35 @@ void main() {
     expect(api.lastMethod, 'alipay');
     expect(c.read(paymentFlowProvider).order?.orderNo, 'pay2');
   });
+
+  test('resume() 成功 → retry 恢复原单会话(不新下单),phase=awaitingPayment', () async {
+    final api = _FakePaymentApi();
+    final c = _container(api);
+    final ctl = c.read(paymentFlowProvider.notifier);
+
+    await ctl.resume('o-month', 'alipay');
+
+    expect(api.retryCalls, 1);
+    expect(api.createCalls, 0, reason: '继续支付不应新下单');
+    expect(api.lastOrderNo, 'o-month');
+    expect(api.lastMethod, 'alipay');
+    expect(c.read(paymentFlowProvider).phase, PaymentPhase.awaitingPayment);
+    expect(c.read(paymentFlowProvider).order?.orderNo, 'o-month');
+  });
+
+  test('resume() 遇 409 ORDER_NOT_PENDING(订单其实已变化)→ failed 自纠,不 crash', () async {
+    final api = _FakePaymentApi();
+    final c = _container(api);
+    final ctl = c.read(paymentFlowProvider.notifier);
+    api.retryError = const AuthApiException(
+        statusCode: 409, messageZh: 'x', messageEn: 'x', code: 'ORDER_NOT_PENDING');
+
+    await ctl.resume('o-month', 'alipay');
+
+    expect(c.read(paymentFlowProvider).phase, PaymentPhase.failed);
+    expect(c.read(paymentFlowProvider).errorZh, isNotNull);
+    expect(c.read(paymentFlowProvider).errorZh, isNotEmpty);
+    expect(c.read(paymentFlowProvider).errorEn, isNotNull);
+    expect(c.read(paymentFlowProvider).errorEn, isNotEmpty);
+  });
 }