How to setup Codex models correcly?

[pauljasperdev]

I was replacing the Claude/Sonnet/Haiku models with 5.4 high/5.4 low/5.4-mini

But opencode kept overwriting ~/.local/state/opencode/model.json with one model variant for GPT 5.4. Or I could overwrite it and 5.4 was the same variant throughout.

I went back to Claude because it just felt more usable.

Any tips how to get this right and usable?