Final review flagged two small gaps in the delete tests: - TestCollection_Delete_Owner_204 now seeds a book and asserts the items table is empty after delete (proves FK CASCADE works). - TestPlaylist_Delete_Owner_FiresRemovedEvent now also asserts the post-delete GET returns 404 (symmetry with the collection test). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>