Connect sign-up to Sendico Facts intake (#46)

frontend/packages/sxchnge_auth/test/backend_test.dart

@@ -10,6 +10,43 @@ import 'package:sxchnge_auth/sxchnge_auth.dart';
 void main() {
   http.Response response(Map<String, Object?> data, [int status = 202]) =>
       http.Response(jsonEncode({'data': data}), status);
+  test(
+    'signup distinguishes support recovery and keeps the retry key',
+    () async {
+      final keys = <String>[];
+      var failed = true;
+      final service = BackendAuthServices(
+        baseUri: Uri.parse('https://api.example/api/v1'),
+        clientId: 'web',
+        client: MockClient((request) async {
+          keys.add(jsonDecode(request.body)['idempotencyKey'] as String);
+          return failed
+              ? response({'error': 'signup_attention_required'}, 503)
+              : response({'userId': 'user'});
+        }),
+      );
+      addTearDown(service.close);
+      const input = SignupRequest(
+        name: 'Ada',
+        email: 'ada@example.com',
+        password: 'password preserved',
+        locale: 'en',
+      );
+      await expectLater(
+        service.signup(input),
+        throwsA(
+          isA<AuthException>().having(
+            (error) => error.code,
+            'code',
+            AuthError.signupNeedsAssistance,
+          ),
+        ),
+      );
+      failed = false;
+      expect((await service.signup(input)).isSimulated, isFalse);
+      expect(keys[0], keys[1]);
+    },
+  );
   test('signup receipt avoids duplicate delivery and subsequent resend reaches API', () async {
     final paths = <String>[];
     final service = BackendAuthServices(
@@ -148,6 +185,34 @@ void main() {
       ),
     );
   });
+  test(
+    'verification recovery preserves assistance instead of requesting retry',
+    () async {
+      final service = BackendAuthServices(
+        baseUri: Uri.parse('https://api.example/api/v1'),
+        clientId: 'web',
+        client: MockClient(
+          (_) async => response({'error': 'signup_attention_required'}, 503),
+        ),
+      );
+      addTearDown(service.close);
+      final provider = VerificationProvider(service);
+      addTearDown(provider.dispose);
+      await provider.send(email: 'ada@example.com', locale: 'en');
+      expect(provider.state.status, VerificationStatus.error);
+      expect(provider.state.error, VerificationError.needsAssistance);
+      await expectLater(
+        service.confirm(token: 'old-token'),
+        throwsA(
+          isA<VerificationException>().having(
+            (e) => e.code,
+            'code',
+            VerificationError.needsAssistance,
+          ),
+        ),
+      );
+    },
+  );
   test(
     'resend preserves server challenge and retries the same delivery key',
     () async {