Add UTC datetime helpers to attempt to fix running issue

backend/app/services/attendance_service.py

@@ -0,0 +1,42 @@
+from datetime import date, datetime, time, timedelta
+
+from sqlalchemy.orm import Session
+
+from ..core.datetime import utc_now
+from ..models.models import AttendanceCheckoutSource, AttendanceSession
+
+
+def duration_seconds(start: datetime, end: datetime) -> int:
+    return max(0, int((end - start).total_seconds()))
+
+
+def close_stale_attendance_sessions(
+    db: Session,
+    cutoff_date: date | None = None,
+    checkout_hour: int = 17,
+) -> int:
+    cutoff = cutoff_date or date.today()
+    cutoff_at = datetime.combine(cutoff, time.min)
+    sessions = (
+        db.query(AttendanceSession)
+        .filter(
+            AttendanceSession.is_open == True,
+            AttendanceSession.checked_in_at < cutoff_at,
+        )
+        .all()
+    )
+
+    now = utc_now()
+    for session in sessions:
+        checkout_at = datetime.combine(session.checked_in_at.date(), time(hour=checkout_hour))
+        if checkout_at < session.checked_in_at:
+            checkout_at = session.checked_in_at + timedelta(minutes=1)
+        session.checked_out_at = checkout_at
+        session.checkout_source = AttendanceCheckoutSource.SYSTEM
+        session.system_flag_reason = "User did not check out before midnight; checkout time was system-set."
+        session.duration_seconds = duration_seconds(session.checked_in_at, checkout_at)
+        session.is_open = False
+        session.updated_at = now
+
+    db.commit()
+    return len(sessions)