Root cause: child model root_validators (Vision ID anti-leakage guard) strip
integer IDs before they can be serialized into the INSERT dict, causing MariaDB
to reject the INSERT with 'Field does not have a default value' (1364).
Fix: re-inject resolved_parent_id into data_to_insert after validated_obj.dict()
in post_child_obj(). This is safe — the integer was already verified against the
DB before model validation.
Affected (were all broken since ~2026-01-27):
- journal/{id}/journal_entry/
- event/{id}/event_session/
- event/{id}/event_person/
- event/{id}/event_registration/
- event/{id}/event_presenter/
- event/{id}/event_presentation/
- event/{id}/event_location/
- event/{id}/event_track/
- event/{id}/event_device/
- event/{id}/event_abstract/
- event/{id}/event_badge/ (different symptom: NULL FK)
Tests: add nested create lifecycle regression tests to test_e2e_v3_demo_parity.py
- POST + Vision check + DELETE for journal/journal_entry and event/event_session
- All 9 checks passing (7s)
Docs: update tests/README.md with accurate demo_parity description and
a 'When to Run Tests' matrix to prevent future gaps in coverage.
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