diff --git a/src/GreenHome.Infrastructure/Services/Device/DeviceMemberService.cs b/src/GreenHome.Infrastructure/Services/Device/DeviceMemberService.cs
index 896d59d..de56cfa 100644
--- a/src/GreenHome.Infrastructure/Services/Device/DeviceMemberService.cs
+++ b/src/GreenHome.Infrastructure/Services/Device/DeviceMemberService.cs
@@ -55,6 +55,9 @@ public sealed class DeviceMemberService : IDeviceMemberService
                 Role = Domain.UserRole.Normal
             };
             _dbContext.Users.Add(user);
+            // کاربر جدید باید ابتدا ذخیره شود تا user.Id مقدار واقعی بگیرد؛
+            // در غیر این صورت DeviceUser با UserId=0 ثبت و FK نقض می‌شود.
+            await _dbContext.SaveChangesAsync(cancellationToken);
         }
 
         var member = await _dbContext.DeviceUsers