Y Combinator’s famed CEO Garry Tan told a SXSW audience that he’s got “cyber psychosis” and is barely sleeping because he’s so excited to be working with AI agents.
“I sleep, like, four hours a night right now,” he told his interviewer, fellow VC Bill Gurley, during an on-stage interview Saturday. “I have cyber psychosis, but I think a third of the CEOs that I know have it as well,” he joked about his current AI obsession. (Tan’s representative confirmed that it was a joke. True AI-induced psychosis can actually be a dangerous condition. )
“Once you try it, you’ll realize: it’s like I was able to recreate my startup that took $10 million in VC capital and 10 people, and I worked on that for two years, and I took anti-narcoleptics — I remember, you know, sort of being on modafinil,” he described, referencing the sleep-preventing drug that’s popular with the startup hustle-culture crowd.
(Tan sold his Y Combinator-backed blogging startup Posterous, to Twitter back in 2012. His current projects involved reworking the Posterous concept, as well as his other startup Posthaven and his issues-oriented site, Garry’s List, his representative tells us.)
But now, his psyche is so amped working with AI agents, it’s a natural insomnia.
“I don’t need modafinil with this revolution. Like, I’m up. I slept at 4 a.m. I woke up at 8 a.m,” he said. “I wanted to sleep more, but I couldn’t because: let’s see what’s going on with the 10 workers. I’ve got like three different projects going right now.”
He’s so excited about his agents that on March 12, just two days before the interview, he proudly, freely shared his Claude Code (CC) setup on Github under an open source license. The setup included six “opinionated” Claude Code skills he developed. Skills are reusable prompts stored in special “skill.md” files that instruct the AI how to behave in specific roles or tasks.
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“I’ve been having such an amazing time with Claude Code, I wanted you to be able to have my *exact* skill setup,” he posted on X. He called his Claude Code setup “gstack.”
gstack is available now at https://t.co/VPvWDzV5c0
Open source, MIT license, let me know if it works for you. It’s just one paste to install it on your local Claude Code, and it’s a 2nd one to install it in your repo for your teammates.
— Garry Tan (@garrytan) March 12, 2026
Since then he’s added several more skills. The gstack GitHub repository currently lists 13, but it seems like every hour Tan tweets about something new.
In one post, he gave an example of how his setup works. First, he gets Claude’s opinion on whether a startup idea or feature is a good idea using a skill where Claude acts like CEO. He uses another skill to have Claude write the feature as an engineer, and another to review its own work for bugs and security issues as a code reviewer. Other skills cover design, documentation, and so on.
The love for gstack began immediately: His tweet went viral on X and trended on Product Hunt. It’s accumulated nearly 20,000 stars on GitHub with 2,200 “forks,” meaning people who have taken the files to modify for themselves.
But shortly after releasing gstack, Tan posted a tweet that caused a heap of hate, too.
He wrote that a CTO friend told him gstack was “god mode” that instantly found a security flaw in his company’s code and predicted it will be widely used.
My CTO friend texted me: “Your gstack is crazy. This is like god mode. Your eng review discovered a subtle cross site scripting attack that I don’t even think my team is aware of. I will make a bet that over 90% of new repos from today forward will use gstack.” https://t.co/P7aOFu5wFM
— Garry Tan (@garrytan) March 12, 2026
To quote just a few of the many hater comments that followed: One founder posted to X, “1) Garry should be embarrassed for tweeting this. (2) If it’s true, that CTO should be fired immediately.”
Vlogger Mo Bitar did a take on gstack called “AI is making CEOs delusional” in which he pointed out that the project was essentially “a bunch of prompts” in a text file. The vlogger summarized the common complaint: developers who use Claude Code already have their own versions of this.
Added one person on Product Hunt, “Garry, let’s be clear and honest: if you weren’t the CEO of YC, this wouldn’t be on PH.”
So who’s right? Is gstack a uniquely useful way to work with Claude Code? Or unremarkable? To find out, I asked the experts, including Claude (which, not surprisingly absolutely loved it). I also queried ChatGPT and Gemini, both of which were surprisingly positive.
Gstack is a group of “reasonably sophisticated prompt workflows, but they’re not ‘magical,’” ChatGPT opined. “The real insight here is that AI coding works best when you simulate an engineering org structure. Not when you just ask: ‘build this feature.’”
Gemini called the setup “sophisticated” adding that “gstack is essentially a ‘Pro’ configuration. It is less about making coding easier and more about making it correct.”
Claude called gstack “a mature, opinionated system built by someone who actually uses it heavily,” adding, “It’s one of the better examples of Claude Code skill design out there.”
We’ll take that as a thumbs up from an expert on the topic.
On Monday, Tan explained in another X post, “I took modafinil just to stay awake longer to be able to turn the momentary crystalline structures I had in my brain into lines of code before sleep or human distraction turned it to grains of sand. I love coding but I love coding with AI even more. I speak it listens and we create. I see the structure and it is built. There is no more powerful an experience to me than that.”
