The four other test files that spelled out `.local/share/wanderbooks` (setup, books_home, format_upgrade, backups) use `default_root` and `platform_data_dir`, so they hold on macOS as on Linux. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp