Switching the OpenClaw agent's runtime from Anthropic Claude (via claude-cli)
to OpenAI Codex (via the native codex harness), with a one-command rollback.
Tested on: OpenClaw 2026.4.25, Codex CLI 0.128.0, Linux/x86_64, root.
Move bot inference off Anthropic Pro/Max (which charges metered "extra usage"