I have a slightly jankier setup.
Generally using Claude Code with Fable 5.1 (high) to plan and implement (Opus 5 (medium) as the implementer subagents), and using Codex with Astra high to review the plan and review the implementers' output.
Using the OpenAI codoex plugin thingy:
I originally had multiple skills for Claude and Codex but found that "ask" is a great single mechanism.
"Ask claude about this"
"Ask codex to implement this"
"Ask claude to review this plan"
etc