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");
         }

backend/src/main/resources/db/migration/V2__align_academic_calendar_weeks_to_monday.sql

@@ -0,0 +1,23 @@
+-- Недели календарного учебного графика выровнены по ISO-неделе:
+-- понедельник — первый день, воскресенье — последний.
+UPDATE academic_calendar_days AS calendar_day
+SET week_number = (
+    (
+        calendar_day.date
+        - academic_year.start_date
+        + EXTRACT(ISODOW FROM academic_year.start_date)::INTEGER
+        - 1
+    ) / 7
+) + 1
+FROM academic_calendars AS calendar
+JOIN academic_years AS academic_year
+    ON academic_year.id = calendar.academic_year_id
+WHERE calendar_day.calendar_id = calendar.id
+  AND calendar_day.week_number IS DISTINCT FROM (
+      (
+          calendar_day.date
+          - academic_year.start_date
+          + EXTRACT(ISODOW FROM academic_year.start_date)::INTEGER
+          - 1
+      ) / 7
+  ) + 1;