Root cause of lost PREP 2016 quiz: deleting a section (e.g. to recreate
with different page ranges) cascade-deleted ALL quizzes attached to it,
destroying the quiz AND all its questions permanently.
Fixes:
- Section.quizzes relationship: removed cascade="all, delete-orphan"
Deleting a section no longer touches quizzes at all
- Quiz.section_id FK: changed to ON DELETE SET NULL, nullable=True
If a section is deleted, quizzes keep working (section_id becomes null)
- DB migration: drops old FK constraint and recreates with SET NULL
Also answers the question about deleting a bank question in a quiz:
- quiz_question_links FK has ON DELETE CASCADE — deleting a question
silently removes it from all quizzes
- This needs a warning UI (not yet implemented — no delete button in bank)
Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
c94640c890