How do I switch models without wiping my config

Use model commands or edit only the model fields. Avoid full config replaces.
Safe options:
/model in chat (quick, per-session)
openclaw models set ... (updates just model config)
openclaw configure --section models (interactive)
edit agents.defaults.model in ~/.openclaw/openclaw.json
Avoid config.apply with a partial object unless you intend to replace the whole config. If you did overwrite config, restore from backup or re-run openclaw doctor to repair.
Docs: Models, Configure, Config, Doctor.