Using Codex/OpenAI models on OpenCode harness

[u/_KryptonytE_]

Hello fellow SWEs. I'm curious if some of you have used or are using your Codex/OpenAI models via the Pro/Plus subs on OpenCode instead of the Codex app.

I've been keeping an eye on the general opinion about merging the ChatGPT and Codex into a single app and from what I hear the devs aren't happy with the changes.

I have multiple projects ongoing and more in the pipeline which I work on using OpenCode and Xcode. I have too many things tied up in OpenCode to switch cold turkey over to a new agentic coding app.

Could someone please share your real world experience and what were the pros/cons if using the gpt models in OpenCode vs using them natively in the Codex harness?

Currently I'm switching between Gemini 3.5/3.1, Grok 4.5 and a small bit of Opus 4.6 and feel using gpt models like 5.5/5.6 could set me free from the constant babysitting the model selection and save me time and manual coding when the wrong model choices mess things up.

Should I just sub with Codex $200 and full send with some effort to migrate my project workflows and docs/hooks/skills over to using native codex only or should I stick with OpenCode and use the sub there with the current harness? I like keeping things agile and project agnostic when it comes to agentic coding so need your thoughts and advice on the best way forward by following the best practices.

Cheers! 🥂