Before/after pair for chapter 4 via temporary version rollback; the two
remaining placeholders (notification inbox, live cursors) need a second
account and are deferred.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0155v2aT8AG1kZDQEZiCLBWC