I'm asking claude code to collaborate with codex. You can do it by adding codex as a mcp server. They added `codex mcp-server` command for user to use codex as a mcp server recently. And it did improve the plan and code quality; I ask it to review the plan and generated code. Full command is like this: `claude mcp add codex -- codex mcp-server`

Check out https://opencode.ai/ it’s similar to Claude code, but works with many models.

Sonnet 4.5 is objectively worse at writing code unless it’s like make me a color picker. IME at least as someone who is going through millions of tokens daily.

Codex high is kind of a beast, even better than Opus which Anthropic decided to limit for their max uses. https://github.com/anthropics/claude-code/issues/8449