Fix: 소셜 로그인 시 providerId가 null일 경우 예외 처리 및 클라이언트 키에 따른 providerId 저장 로직 추가

Author: minsukim-29cm

src/main/java/com/fund/stockProject/auth/service/AuthService.java

@@ -127,6 +127,9 @@ public String register(OAuth2RegisterRequest oAuth2RegisterRequest, String clien
             MultipartFile image = oAuth2RegisterRequest.getImage();
             String imageUrl = (image != null && !image.isEmpty()) ? s3Service.uploadUserImage(image, "users") : null;
             String providerId = resolveSocialProviderId(oAuth2RegisterRequest, provider, clientKey);
+            if (providerId == null) {
+                throw new IllegalArgumentException("Social registration context expired. Please retry social login.");
+            }
             String email = resolveRegistrationEmail(oAuth2RegisterRequest, provider, providerId);
             Boolean marketingAgreement = oAuth2RegisterRequest.getMarketingAgreement() != null
                     ? oAuth2RegisterRequest.getMarketingAgreement()
@@ -166,6 +169,7 @@ private String resolveSocialProviderId(OAuth2RegisterRequest request, PROVIDER p
             if (provider == PROVIDER.APPLE) {
                 return pendingProviderId
                         .or(() -> appleLoginContextService.extractProviderIdFromFallbackEmail(email))
+                        .or(() -> appleLoginContextService.consumePendingProviderIdByClient(PROVIDER.APPLE, clientKey))
                         .orElse(null);
             }
             return pendingProviderId.orElse(null);

src/main/java/com/fund/stockProject/auth/service/OAuth2Service.java

@@ -112,6 +112,9 @@ public LoginResponse appleLogin(String code, String state, String userJson, Stri
         Optional<User> userOptional = userRepository.findByEmail(email);
         if (userOptional.isEmpty()) {
             appleLoginContextService.savePendingProviderId(PROVIDER.APPLE, email, providerId);
+            if (clientKey != null && !clientKey.isBlank()) {
+                appleLoginContextService.savePendingProviderIdByClient(PROVIDER.APPLE, clientKey, providerId);
+            }
             return new LoginResponse("NEED_REGISTER", email, null, null, null, null);
         }