I’m actively doing that for a fun side project - systematically rewriting SQLite in Rust. The goal is to preserve 100% compatibility, quirks and all. First I got it to run the native test harness, and now it’s basically doing TDD by itself. Have to say, with regular check-ins, it works quite well.
Note: I’m using the $20 plan for this! With codex-5.2-medium most of the time (previously codex-5.1-max-medium). For my work projects, Gemini 3 and Antigravity Claude Opus 4.5 are doing the heavy lifting at the moment, which frees up codex :) I usually have it running constantly in a second tab.
The only way I can now justify Pro is if I am developing multiple parallel projects with codex alone. But that isn’t the case for me. I am happier having a mix of agents to work with.
That is a good use-case as well and would definitely require a codex Pro subscription.
I've been doing something like this with the basic Gemini subscription using Antigravity. I end up hitting the Gemini 3 Pro High quota many times but then I can still use Claude Opus 4.5 on it!
I like Pro also for better access to 5.2 Pro which is indispensable for some problems and for producing specs/code samples. I use https://gitingest.com
Note: I’m using the $20 plan for this! With codex-5.2-medium most of the time (previously codex-5.1-max-medium). For my work projects, Gemini 3 and Antigravity Claude Opus 4.5 are doing the heavy lifting at the moment, which frees up codex :) I usually have it running constantly in a second tab.
The only way I can now justify Pro is if I am developing multiple parallel projects with codex alone. But that isn’t the case for me. I am happier having a mix of agents to work with.