NewDraft owns insert (partial write on a throwing hook), refuse and discard (via
Rollback::attempt and WriteFailed::*) and the partial logging; ContentCreateAbility
keeps checkDivi/prepare/combined (Errors::fieldsOf) and the result. Both discard
callers still pass REASON_EXTRAS. Behaviour unchanged; NewDraftTest adds the
throwing-delete branch.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>