New books dirs get .codex/hooks.json beside .claude/settings.json; both SessionStart hooks run one justfile recipe, which reports the viewer's state per [viewer] open_at_start (and opens it itself for "always"). Codex runs project hooks only once the dir is trusted and the hook approved, so new --codex says so; AGENTS.md stays the fallback. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Tpv1gBaepKjQiAVJqejGbA