There are two ways to do it,, here’s how:
Option 1, the official plugin: /plugin marketplace add openai/codex-plugin-cc /plugin install codex@openai-codex /reload-plugins, then /codex:setup
That unlocks /codex:review, /codex:adversarial-review, and /codex:rescue. Claude writes, GPT critiques, you ship.
Option 2, the proxy. One alias makes Sol your main model:
alias claudex=‘CLAUDE_CODE_SUBAGENT_MODEL=gpt-5.6-sol CLAUDE_CODE_ALWAYS_ENABLE_EFFORT=1 claude –model gpt-5.6-sol’
Bonus: Claude Code lets you set subagent model and effort yourself.
Sol Ultra runs can burn several times the tokens of a base run, so right-sizing delegated work saves real money.