комит

backend/src/main/java/com/magistr/app/service/AcademicCalendarGridService.java

@@ -114,7 +114,8 @@ public class AcademicCalendarGridService {
 
     private void validateWeek(AcademicYear academicYear, LocalDate date, Integer weekNumber) {
         long daysFromYearStart = ChronoUnit.DAYS.between(academicYear.getStartDate(), date);
-        int expectedWeek = Math.toIntExact(daysFromYearStart / 7 + 1);
+        int daysBeforeYearStartInFirstWeek = academicYear.getStartDate().getDayOfWeek().getValue() - 1;
+        int expectedWeek = Math.toIntExact((daysBeforeYearStartInFirstWeek + daysFromYearStart) / 7 + 1);
         if (weekNumber != expectedWeek) {
             throw new IllegalArgumentException("Номер недели не соответствует дате учебного года");
         }