--cmd exits 0 (+ optional --matches regex) or --timeout; exit 0/3/1, last output always printed, --then hook composes with notifyr. Injectable runner for tests + real-shell integration test. Spec: doc/tool-parity.md 3.2. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_011KikHkfCiC3yELbsMN8fT9