Validation completed:
- PHP syntax check passed: install.php
- PHP syntax check passed: payload/student/exams.php
- PHP syntax check passed: payload/teacher/exams.php
- PHP syntax check passed: payload/admin/exams.php
- Installer payload paths verified.
- Student status normalization marker verified.
- Exact end-time comparison verified.
- Attempt expiry capped by End At verified.
- Reopen Now logic verified in teacher and admin files.
- Completed / In Progress / Not Taken roster queries verified in teacher and admin files.
- Result visibility after global closure verified in student file.
- Teacher schedule input precedence verified: entered dates override Open Now.
