BREAKING:

GPT-5.6 Sol is out—AND Codex has been merged into ChatGPT Desktop as ChatGPT Codex. This combo model and desktop app harness are the gold-standard for knowledge work in AI.

5.6 is powerful, fast, half the price of Fable, and my default for almost everything.

We’ve been testing it internally @every for about a month across coding, writing, design, and knowledge work.

Here’s our day-zero vibe check:

• An A-tier coder—but it’s not Fable. Sol scored 56/100 on our Senior Engineer benchmark compared to a 91 for Fable. I think the 56/100 undersells it, it’s an excellent implementor, and very smart. But Fable just writes conceptually cleaner code and works better at the top end of task complexity.

PRO-TIP: Use GPT-5.6 as Fable’s subagent for the most goated combo in AI coding.

• The best writer of the frontier models. It’s clearer and more concise than Fable or Opus 4.8, without the overexplaining or weird private language. It can one-shot marketing emails, help you workshop taglines, and explain complex concepts clearly. It’s also super fast, which makes it easy to collaborate with.

• Design is better, but not top-tier. It has noticeably more taste than 5.5, but Fable and Opus 4.8 are still playing at a different level. See examples in the video and vibe check below.

• The real leap is knowledge work. Sol is the first model I’ve trusted to run whole loops of knowledge work—not just help with individual tasks. I use it to process email, surface decisions from meetings and Slack, find job candidates, scan Facebook Marketplace for furniture, and log my meals. It has shifted my job from doing the work to tending the system that does it.

• The merged app is fine. I was extremely worried about this because I love the Codex app. OpenAI was caught in an interesting position: How to make an agent orchestration app for regular ChatGPT consumers, coders, and businesses all in one app. They now split the interface between ChatGPT Work and ChatGPT Codex. They’re basically the same except Work hides code. And “Chat” has been demoted to 2nd tier status for quick questions in either one.

It’s not a big leap, but it’s not a huge setback either. And it remains my favorite of the desktop agent orchestration apps.

Verdict: If I really had to put my finger on it, I’d say Fable has way more big model smell. But that means it’s a skill in itself to get value out of it—99% of people are still not there yet.

GPT-5.6 is almost as powerful, but is easy to use, fast, and relatively cheap. It should give you an early sense of where model work is going.

Full @every Vibe Check: https://every.to/vibe-check/gpt-5-6…

Vibe Check: GPT-5.6 Sol Is Our Favorite Model to Collaborate With

Source: https://every.to/vibe-check/gpt-5-6 We missed GPT-5.6 Sol while it was gone.

For about a month, Sol had been everywhere in our work. It keptDan Shipperat inbox zero and tracked decisions across meetings and Slack that he might otherwise have missed. It kept up withAustin Tedescoas he moved from campaign idea to email to landing page to experiment without making him repeat himself or lose focus. It retrieved files and context for me (Katie Parrott) so quickly that it completely rewired how I work with models day to day.

Then, at the end of June, we lost access while Sol went throughgovernment review. Dan said returning to other models—even with Fable available—felt like going back to the Stone Age. Austin compared using GPT-5.5 to “trying to shoot a basketball that’s twice as heavy as the one I’m used to using.” In ourSonnet 5 Vibe Check, we talked about the revolution of rising expectations. Our time without Sol underscored just how quickly you can get used to a higher standard of living—and how much it hurts when that progress rolls back.

GPT-5.6 Sol is a serious step change in model capability for day-to-day knowledge work. It’s fast enough to keep up with you, resourceful enough to find the context it needs to do good work, persistent when the first approach fails, and responsive when you change direction.

For months now, we’ve been tracking a split in the way we work with AI. Sometimes, you want to delegate—give the model an assignment, send it off, and come back to something you can work with. Other times, like when you’re working on a long complex report or a big writing project, you want to collaborate—stay close to the work, see options quickly, and make decisions that guide the outcome as the work evolves. Sol’s mix of speed, intelligence, and steerability make it a delight for that second kind of work.

Fablestill gets the biggest, most ambiguous assignments—the ones where planning and making decisions about the work is a large part of the task. Austin uses it for long-running, go-to-market engineering tasks, like setting up new user journeys, testing them end to end as different audience types, and working in a loop to continue to improve the flow. Dan goes to it for benchmarking projects that involve a lot of synthesis, dataset development, and experimentation. But once we’re done delegating and ready to dig in, GPT-5.6 Sol is where we want to spend our time.

New model releases seldom come unaccompanied these days, and today is no exception. In addition to GPT-5.6, OpenAI is merging the ChatGPT and Codex desktop experiences into one unified app. The move appears to be a bid to build a bigger tent for agentic work—one that pulls in more of ChatGPT’s 800 million-plus users.

Our time with the new app experience has been limited, but so far, likeCodexbefore it, it’s an app we want to spend time in. Which is great news, because GPT-5.6 Sol is a model we want to spend time with. Dan’s analogy is that Sol is a Porsche and Fable is a warp drive. Fable can take you across the galaxy, sure. But most of the time, you’re not going to space—you’re just trying to get around town. Sol is the model that lets you travel in style.

More on our experience driving it below.

What OpenAI is saying

OpenAI calls Solits “strongest model yet,” but the evidence it released is concentrated in a particular kind of work: difficult assignments that require an agent to plan, use tools, and keep working. The company says Sol sets a new state of the art on Terminal-Bench 2.1, which tests command-line tasks that require planning, iteration, and tool use. It also reports stronger results thanGPT-5.5on a long-running biology benchmark and the company’s best cybersecurity performance.

A newmaxreasoning setting gives one Sol agent more time to work, while anultramode coordinates several agents on the same assignment. OpenAI is also debuting new model tiers below the Sol tier: Terra is the lower-cost model for everyday work, and Luna is the fastest and least expensive. OpenAI says those names will persist as capability tiers even as the models within them advance.

OpenAI is debuting GPT-5.6 alongside another major product update: merging the ChatGPT and Codex desktop experiences into one app. ChatGPT Work is geared to take on the majority of knowledge work tasks, while Codex gets its own dedicated tab for technical work.

On the pricing front, OpenAI’s three tiers map closely onto Anthropic’s trio of models. Sol costs $5 per million input tokens and $30 per million output tokens, matchingOpus 4.8on input but costing $5 more on output. Terra costs $2.50 and $15, compared withSonnet 5’s introductory $2 and $10 through August 31; Sonnet then rises to $3 and $15. Luna costs $1 and $6, matchingHaiku 4.5on input and costing $1 more on output.

Sol

$5 input / $30 output

per million tokens

Terra

$2.50 input / $15 output

per million tokens

Luna

$1 input / $6 output

per million tokens

The Reach Test

Dan ShipperThe multi-threaded CEO

“GPT-5.6 Sol in ChatGPT Codex and Work is obviously the gold standard for knowledge work. I reach for it first as my daily driver for pretty much every task. It’s not Fable-level—I flip back to Fable for my hardest tasks—but for everything else 5.6 is my go-to.”

Kieran KlaassenFather of compound engineering

“Sol is a workhorse model. I trust it more as a collaborator than previous GPT models: It’s thorough and helpful, doesn’t do stupid things, and is creative enough to just get shit done. Fable is still better at complex, long-horizon tasks, but Sol can do about 90 percent of what Fable can do.”

Austin TedescoHead of growth with an agentic edge

“Sol is the best knowledge-work model I’ve used, inside the best app for knowledge work. It now handles at least 80 percent of my day-to-day tasks and can take on basically anything my brain naturally thinks to try. I still want Fable running in the background for the work I have to push myself to consider possible.”

Mike TaylorChief PowerPoint engineer

“Sol has turned into my daily driver. I still prefer Fable’s sharp spiky intelligence and use of context but GPT-5.6 is the best and most cost-effective all round model that I would use every day.”

Katie ParrottAI-pilled writer by day, vibe coder by night

“The combination of 5.6 and Codex has seriously transformed the way I approach work from day to day, and for that alone, I consider this to be a paradigm-shifting model. For writing specifically, I’ve found Sol to be stronger than Claude models at using context like style guides and samples to inform its work, and its speed and ability to take direction make it great for collaborative writing. But truly human-level prose remains an elusive target for frontier models in a way that makes me wonder whether we’ve reached a plateau in what AI is capable of on the writing front.”

Andrey GalkoEngineering co-lead

“Sol is making me trust GPT models for coding again. It does less random stuff, needs fewer follow-ups, and carries more work end to end than GPT-5.5. I still prefer Fable, and sometimes Opus, partly because Codex hides too much of the process and I don’t always understand how it got there.”

Naveen NaiduVoice-pilled engineer

“GPT-5.6 Sol has been my go-to model for the past month—and the most reliable one I’ve used. Since Fable launched, my workflow has settled into a powerful split: Fable acts as the orchestrator, shaping the plan, and Sol executes it. That combination has helped me ship a remarkable amount for Monologue, from major improvements to Notes to building the entire Monologue web app in a day. Sol remains the model I trust most for day-to-day development of Monologue’s native apps.”

Arielle ShipperLover of CSVs and spend reports

“So far, I prefer Sol for knowledge work because it gives me granular control without making me manage every small decision. It can take initiative, ask useful questions, and still let me see where the work is going. Early testing felt truly magical with its abilities compared to 5.5, but a late-testing calculation error gave me whiplash. I’ve been using Codex as my primary work surface for awhile, so if I can rebuild trust, Sol will be a game-changer for me.”

Jack ChengSenior editor and expert dabbler

“Sol is faster and more meticulous than Fable; the GPT model is my new go-to for helping me with spot edits that involve dejargonifying overly technical language or rewriting lines that, even if human-written, sound too much like AI. If I could only pick one model for collaborative work, it would be Sol. That said, Fable has better, dare I say,taste; I trust its judgment more on large architectural decisions and UI design. And I don’thaveto pick one model. I can have Fable tell Sol or Opus/Sonnet to execute, or have Sonnet 5 ask Fable to consult on tough problems. I don’t use these models in isolation, and I don’t think others should either.”

Legend:

Paradigm shift

Psyched about this release

It’s okay, but I wouldn’t use it every day

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