OpenAI Announces GPT-5.6 Sol, Terra, and Luna Launch This Thursday
GPT-5.6 Sol, along with Terra and Luna, will launch publicly this Thursday

We are thrilled to announce that GPT-5.6 Sol, alongside Terra and Luna, will launch publicly this Thursday. As part of this major update, we are immediately expanding preview access globally, inviting users worldwide to experience these new capabilities firsthand.
GPT-5.6 Sol, along with Terra and Luna, will launch publicly this Thursday.
- laurels-marts
Damn this is exciting. I love that gpt models are much faster, efficient and cheaper than Claude models. They are so fast even on high/xhigh that I don’t find myself using the parallel agent setup anymore much since its cognitively less demanding to just follow along what the model is doing and most tasks it will complete in <5-<10mins anyway.
- aarvin_roshin
Thoughts[^0] from Theo, who had early access:
> It's a damn good model. Not quite as "smart" as Fable, but it is incredibly capable. Fixed all the problems I had with GPT-5.5.
> It is incredibly determined. Will run for a day without even using a /goal. It understands subagents incredibly well and is great at orchestrating. It's super pleasant in use cases like OpenClaw and Hermes Agent. It knows iOS dev incredibly well.
> It has rough edges too, but FAR fewer than 5.5 did.
> For many things, gpt-5.6-sol will become my obvious defaults.
> It is better about [following instructions] than 5.5 was. Understands intent well and hammers until it gets there. Sometimes a bit too hard.
Also[^1]:
> gpt-5.6-sol is world leading in computer use. It made me use it 100x more. When we lost access to 5.6, I quickly started to go insane without it
- reassess_blind
I’m bouncing back between Codex and Claude like a ping-pong ball. I much prefer the experience using Codex, less verbose and to-the-point I’ve found. But Fable, being as strong as it is, is a big draw for Claude right now. I’ll likely switch back to Codex if 5.6 Sol is comparable.
- elAhmo
I know a few of my comments are related to this, but these new names are horrible. Why introduce ANOTHER layer of confusion and drop the mini, nano suffixes that people got used to?
How does this go through so many layers of management at a trillion dollar company without who has a say raising this? I simply can't believe how stupid the naming scheme from OpenAI was and continues to be even after they acknowledged it earlier.
- bottlepalm
Coding with AI it feels like if you're not using the best model then you're possibly missing out - creating less capable, maintainable, just plain 'good' code. Why waste time using anything less than the best and cleaning up the mess later on. This is why I feel like local models and Chinese models aren't taking off (and Gemini/Grok) - they work, but they're plain just not as good as OpenAI/Anthropic. If you have the money then it doesn't make sense to code with anything else.
- mhrmsn
Is this the reason Anthropic extended use of Fable 5 via subscriptions until July 12? Seems a bit like it
- jorisw
Mirror: https://xcancel.com/OpenAI/status/2074704958419792299
- small_model
Fable 5 for the planning, thinking, reasoning part, then GPT 5.5 to implement is an almost perfect combo, with Fable then reviewing GPT's code.
Codex CLI just seems faster at coding than Claude Code but Fable is just a level above intelligence wise, it's truly like taking to very very very smart human.
With GPT 5.6 though will be interesting to see if things flip, to have Codex speed (or faster) with Fable level intelligence is a game changer.