PASS: idempotent setup
PASS: wrong exam session rejected
PASS: completed exam rejected
PASS: unmapped subject rejected
PASS: section-scoped roster
PASS: empty draft for only assigned students
PASS: overlapping all-section assignment blocked
PASS: mismatching total marks rejected
PASS: teacher cannot save another teacher entry
PASS: marks greater than maximum rejected
PASS: negative marks rejected
PASS: student from another section rejected
PASS: draft does not publish exam marks
PASS: stale revision rejected
PASS: incomplete submit rejected
PASS: complete submission queued
PASS: submitted entry locked
PASS: approved entry locked
PASS: approved marks saved to existing exam_marks
PASS: explicit absent grade preserved
PASS: duplicate approval rejected
PASS: admin can reopen approved entry
PASS: concurrent admin edit protected
PASS: concurrent mark not overwritten
PASS: reopen refreshes changed official marks
PASS: zero and absent stored distinctly
PASS: revoked assignment rejected
PASS: interrupted publishing can be retried without duplicate marks
ALL WORKFLOW CHECKS PASSED