hooks/hooks.json

{
  "hooks": {
    "SessionStart": [
      {
        "matcher": "startup|resume|clear|compact",
        "hooks": [
          {
            "type": "command",
            "command": "node ~/.codex/hooks/codex-session-mapping.cjs",
            "timeout": 5
          }
        ]
      }
    ]
  }
}