Mirror the blocks path's error handling in the markdown engine: - page + DB markdown two-phase image append now check append_to_page's return and exit(1) on failure instead of printing success silently - markdown DB upsert guards update_page_properties return - restore blocks-engine page progress print + replace-failure print - move unused parent computation into the create branch Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>