fix(auth): avoid gap locks when creating accounts

auth/src/main/java/com/baiyue/auth/service/AccountManagementService.java

@@ -9,6 +9,7 @@ import jakarta.annotation.Resource;
 import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.dao.DuplicateKeyException;
 import com.baiyue.common.audit.BusinessAudit;
 
 import java.util.Locale;
@@ -63,7 +64,9 @@ public class AccountManagementService {
         String appCode = request.appCode() == null ? "MERCHANT"
                 : request.appCode().trim().toUpperCase(Locale.ROOT);
         validateScope(appCode, request.tenantId());
-        AuthAccount existing = repository.findById(request.accountId());
+        // Locking a missing key takes an InnoDB gap lock and can deadlock
+        // unrelated account inserts. The unique indexes arbitrate creation.
+        AuthAccount existing = repository.findCurrentById(request.accountId());
         if (existing != null) {
             if (sameIdentity(existing, request, appCode)) return summary(existing);
             throw new BizException(ResultCode.CONFLICT, "认证账号标识已被其他成员使用");
@@ -88,7 +91,13 @@ public class AccountManagementService {
         account.setDefaultMembershipId(request.membershipId());
         account.setDefaultAppCode(appCode);
         account.setDeleted(0);
-        repository.insert(account);
+        try {
+            repository.insert(account);
+        } catch (DuplicateKeyException duplicate) {
+            AuthAccount winner = repository.findById(request.accountId());
+            if (winner != null && sameIdentity(winner, request, appCode)) return summary(winner);
+            throw new BizException(ResultCode.CONFLICT, "认证账号标识或登录账号已被使用");
+        }
         return summary(account);
     }