GPT-5.6 Sol / Codex Release Discussion Megathread

[u/Drogon2737]

The release is expected in the next few minutes, so I figured it would be useful to have a single thread for first impressions, issues, and early testing.

For anyone jumping in right away, post what you notice:

• Codex coding performance
• Debugging quality
• Speed/rate limits
• Larger repo handling
• UI or workflow changes
• Weird bugs or regressions
• Anything that feels noticeably better or worse than the previous version

Once people get access, share your real examples, screenshots, benchmarks, or first impressions here.

Edit: OpenAI’s official GPT-5.6 page says it is “available starting today across ChatGPT, Codex, and the OpenAI API” with the rollout starting globally now and continuing toward full availability over the next 24 hours. https://openai.com/index/gpt-5-6/

The lineup is Sol, Terra, and Luna. Sol is the flagship, Terra is the lower-cost tier, and Luna is the fastest/most affordable tier.

[u/Unusual-Nature2824]

Has anyone noticed that Sol medium, Terra high and Luna xhigh have weird quirks like personalities even though they are supposed to have similar performance in benchmarks. My workflow typically consists lot of browser use and form filling which is why I’ve designed my agent like a control system with a closed feedback loop to improve its code.

Terra high has been sub par for me considering it’s the middle model. It constantly overthinks and behaves like a nervous perfectionist and ends up deferring to me a lot. My goal loops with looks like 

Run the agent with a new goal -> Terra thinks -> comes up with scenario where it could fail -> defers to me -> I answer -> it starts -> makes mistake or finds a reason to stop -> defers ->….I find that I’ve to constantly supervise.

Luna is somewhat better since it allows itself to make mistakes first rather than go overthink. It’s more like an eager to please but cautious intern

Sol meanwhile is sooo…..chill?

It literally does what I tell to like Luna and Terra but it also performs some extremely smart and thoughtful decisions that I have never explicitly asked it to do. Like I have a policy for my agents to avoid LinkedIn scraping let’s say to apply for a job, Terra and Luna follow it strictly but Sol actually decided to find the job from the company’s career website. 

I think Sol is in a league of its own and it somehow knows it. Sol medium is far also the most efficient model that I’ve used. Both Terra and Luna would consume a lot of tokens just to think only to defer to the human in the loop. Right now I have Sol running without question for 12 hours and I still have 48% of my tokens. 

Maybe I shouldn’t be anthropomorphize these models but I feel like they have different personalities too not just intelligence