issue #2551

BMA.EHR.Infrastructure/Persistence/LeaveDbContext.cs

@@ -61,5 +61,18 @@ namespace BMA.EHR.Infrastructure.Persistence
         {
             base.Entry(entity).State = EntityState.Detached;
         }
+
+        protected override void OnModelCreating(ModelBuilder modelBuilder)
+        {
+            base.OnModelCreating(modelBuilder);
+
+            // Composite unique index on the natural key for LeaveBeginning.
+            // Prevents duplicate rows when concurrent requests (e.g. UI calling /user/check twice)
+            // race through the get-or-create flow in LeaveBeginningRepository.
+            modelBuilder.Entity<LeaveBeginning>()
+                .HasIndex(b => new { b.ProfileId, b.LeaveYear, b.LeaveTypeId })
+                .HasDatabaseName("IX_LeaveBeginnings_ProfileId_LeaveYear_LeaveTypeId")
+                .IsUnique();
+        }
     }
 }