The reader and the fact tables were siblings keyed by the same language, so React left the first edition's reader on screen and appended the new one. Distinct keys per sibling; whole-page switch test with real engine fact tables. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01N4f2nya58RoRu4yEmJgRGE