This is a column about AI. My fiancé works at Anthropic. See my full ethics disclosure here.

I.

Lately, the only important question about a new large language model has been whether the Trump administration would allow anyone to use it. On Thursday, though, not one but two notable models became available for use: GPT-5.6, from OpenAI, and Muse Spark 1.1 from Meta.

As always, the worst day to evaluate new models is the day they come out. Still, there was plenty of news and relevant commentary surrounding both releases, and it’s worth checking in on both companies as their strategies and products evolve.

Start with OpenAI, which earlier in the week released an impressive new voice model alongside possibly the best ad it has done to date. After some testing, M.G. Siegler says the latest model is good enough that “we're now fully on the cusp of a true shift in computing” where voice becomes a primary method of input. Among other things, he writes, that’s good for OpenAI’s hardware ambitions: “These new GPT-Live capabilities seem like they're going to unlock the space to the point where new devices may now be not just possible, but inevitable.”

It turned out that GPT-Live was merely the prelude to a larger set of announcements today. The company (confusingly) merged Codex into the desktop app, introduced the ChatGPT Work agent, and retired its Atlas browser. Most importantly, the company released GPT-5.6 in three versions that correspond roughly to “good,” “better,” and “best”: Luna, Terra, and Sol.

In its blog post, OpenAI notes benchmarks where Sol outperformed Anthropic’s industry-leading Claude Fable model, including Agents’ Last Exam and the Artificial Analysis Coding Agent Index. People who got early access were generally enthusiastic. Every’s Katie Parrott called GPT-5.6 “our favorite model to collaborate with,” though “Fable still gets the assignments we want to hand off completely.”

On the whole, though, she said the model represents “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.”

Box CEO Aaron Levie was similarly enthusiastic, writing on X that Sol represents “a big step up from GPT-5.5, especially on complex data-oriented tasks that require deep reasoning and analysis.”

On the Sol vs. Fable question, opinions varied widely. HashiCorp founder and Ghostty creator Mitchell Hashimoto said he would use the models for different things, but expressed a general preference for Sol. “It is faster, plans/judges just as good as Fable, and I think produces better overall work,” he wrote. “I’ll reach for Fable still for highly targeted debug or performance work with clear reward functions.”

Meanwhile, Figma CEO Dylan Field discouraged making direct comparisons. “This is a mistake,” he wrote. “They are apples and oranges.” (Sol is “very good,” he added.)

To Wharton School professor Ethan Mollick, though, there was at least one comparison that matters: “My big takeaway is that both Sol & Fable represent jumps over previous models and have opened a large gap with the next-best AIs,” he wrote. “People will have preferences for one or the other, but if you [are] doing any work where better intelligence matters, those two models are your only choices.”

II.

The broad enthusiasm for GPT-5.6 will likely come as a relief to OpenAI as it weathers another news cycle about instability in its executive ranks. Fidji Simo, the company’s No. 2 executive, told staff members Thursday that she plans to step down from the company less than a year after joining it as its CEO of applications, the Wall Street Journal reported. Simo said that her chronic illness, postural orthostatic tachycardia syndrome, had worsened. She will become an adviser to the company.

Simo joins a list of other high-profile leaders to depart OpenAI this year, including its chief futurist, Joshua Achiam; vice president of research Jerry Tworek; former chief product officer Kevin Weil; recently returned head of enterprise sales Barret Zoph; model behavior lead Joanne Jang; and researcher Max Schwarzer, among others.