I use plan mode in claude code, then use gpt-5 in codex to review the plan and identify gaps and feed it back to claude. Results are amazing.
If you're not already doing that you can wire up a subagent that invokes codex in non interactive mode. Very handy, I run Gemini-cli and codex subagents in parallel to validate plans or implementations.
Yeah, I’ve used vatiations of the “get frontier models to cross-check and refine each others work” pattern for years now and it really is the path to the best outcomes in situations where you would otherwise hit a wall or miss important details.