harness-tools/extensions/interactive-subagents/pi-extension/subagents/plugin/hooks/hooks.json

{
  "hooks": {
    "Stop": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "${CLAUDE_PLUGIN_ROOT}/hooks/on-stop.sh",
            "timeout": 10
          }
        ]
      }
    ]
  }
}