
Co-founder of @Recursive_SI. ex-Meta FAIR Director. ex-Google. Reasoning, Optimization and Understanding LLM. Novelist in spare time. PhD in @CMU_Robotics.
California, USA
Joined December 2009
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Today, we release our first model, Flint-40B-A2B, a fast local coding model built with our automated research system. huggingface.co/RecursiveSI/f…
1. Strong performance. 54.9% on Terminal-Bench 2.1, 89.7% on SWE-bench Pro v2, and 74.2% on SWE-bench Verified.
2. It is trained from scratch (tokenizer->Pretrain->Midtrain->SFT->RL).
3. Fast in your local laptop. Up to 2x faster than comparable models: 125+ tokens/sec on a MacBook Pro, 150+ on RTX Spark.
4. We build the complete model training pipeline in 4 month!
Introducing Flint, @Recursive_SI’s first model: a fast local coding model built with our automated research system, the Eureka Machine.
• Best-in-class fast local coding
• Up to 2x faster than comparable models: 125+ tokens/sec on a MacBook Pro, 150+ on RTX Spark
• Built from scratch in under 4 months
Private, unmetered intelligence on your own machine. Open weights available now on @huggingface, run it locally on your favorite framework or try it for free on @opencode or @pidotdev.
Yuandong Tian retweeted
apparently Flint is "scary good"
Recursive makes the case that the benefits of using AI to build AI outweigh the risks. buff.ly/xsPUDpl
We’re about to see a breakout in local model capabilities.
Flint scores 54.9% on Terminal-Bench 2.1 with ~2B active parameters. That’s ahead of every other small MoE and two of the three dense ~30B models.
It only needs about 24GB and runs at 125+ tok/s on a MacBook Pro.
Yuandong Tian retweeted
Recursive Flint is here: our first model, built with the Eureka Machine. Fast, local coding. Open weights available on Hugging Face.
Introducing Flint, @Recursive_SI’s first model: a fast local coding model built with our automated research system, the Eureka Machine.
• Best-in-class fast local coding
• Up to 2x faster than comparable models: 125+ tokens/sec on a MacBook Pro, 150+ on RTX Spark
• Built from scratch in under 4 months
Private, unmetered intelligence on your own machine. Open weights available now on @huggingface, run it locally on your favorite framework or try it for free on @opencode or @pidotdev.
👉👉 AI Scientific Discovery Demos with our Recursive Flint-40B-A2B 🪨🪨!
A great read. The blog post captures years of progress in mechanistic interpretability and offers an optimistic vision: perhaps we really can open the black box and understand how neural networks work.
I share that optimism, but with some reservations.
I'm skeptical of explanations that stop at individual neurons, accompanied by compelling visualizations that seem to "explain everything."
Humans are remarkably good at convincing themselves. It's easy to cherry-pick evidence that supports a hypothesis, especially when the visualizations look convincing.
I'm also not convinced that "Recursive Generalization" is fundamentally different from hierarchical representation learning. As representations become more abstract, they discard details while preserving invariances. Isn't that essentially what hierarchical representations have always been about?
IMHO, we need to move beyond a largely descriptive, behavioral approach toward a principled mathematical framework. And we have a natural starting point: gradient descent.
Rather than just asking what a network has learned, we should understand why learning dynamics produce these structures in the first place.
Of course, this is extraordinarily difficult. Look at OpenAI's 719 mathematical proofs. We see plausible proofs tackling problems at the Fields Medal level, yet no comparable breakthrough that cracks deep learning theory. That contrast is striking.
Part of the difficulty is that there are countless plausible theories of how deep networks work. Proving even one can be mathematically formidable. And a proof alone isn't enough. Each theory needs empirical validation, often requiring substantial GPU compute. It's a daunting combination of mathematical and experimental challenges.
Still, I believe this is the way forward. Interpretability gives us observations and hypotheses. But ultimately, we need a theory that explains why these phenomena emerge from the learning process itself.
That's how we turn compelling stories about neural networks into actual understanding. And hopefully recursive self-improvement can help with that 😀
interpretability might be the most important scientific problem in the world right now, as I don't think we can solve alignment if we don't know what we're building. I think I have good news about it. I co-authored early work in mechanistic interpretability at OpenAI and came away pessimistic, because neural networks appeared to fold into arbitrary tangled knots. years later, I started openai's first large-scale automated interpretability project, finding about 2% of neurons legible with the primitive tools we had
with modern agentic tools and a much closer look, the picture looks totally different. the vast majority in models up to trillions of parameters are legible, and their circuits beautiful. many famous examples of tangled neurons turned out to be misunderstood. The roadblocks I expected mostly aren't there. I now think ambitious interpretability will be solved by the time we need it most, and possibly quite soon, as automated scientists keep improving. it may be a bitter lesson for interpretability: the simple thing, at absurd scale, works
already-clean.goodfire.com/
Thanks for the interview @ziv_ravid! It is a fun discussion 😀
New episode on The Information Bottleneck, with Yuandong Tian @tydsh (previously at Meta and now a co-founder of Recursive Superintelligence).
He told us that after writing his last paper at Meta with GPT-5, he realized his job could be replaced in five years. "Instead of losing my job involuntarily, I think it's good to start a company."
But he also says the models still can't come up with good ideas. You ask for one, and you get something mediocre that everyone already thought of.
We also talked a lot about RL, Go, Continuous Latent Space CoT reasoning (Coconut), and the calls to restrict self-improving AI.
I’m sure you will enjoy it. You can find the episode on our website, YouTube, and all the apps
Will be in CoLM conference this Friday afternoon. Won't be able to give a talk (too busy!) but will still join the panel in wdlctc.github.io/efficient-r…. See you all~
We got exact the same comments when we published Coconut😀. However, even with explicit CoTs, the model can still learn to hide the true thinking process. The ultimate solution is always to understand how the model works.
😅 so our StreamingLLM (the original attention sink paper) strikes back again? 😅 -- Caveat: it is in post-training setting.
Simple beats complicated:
We show that switching to a sliding-window attention mask with attention sinks (at no cost) beats linear attention post-training.
Huge thanks to my collaborators @RheaSukthanker, @CameronPashmina, and @Emy_Aze.
Paper: arxiv.org/abs/2608.28444
Interesting findings by our automatic system😆 It finds that some FlashInfer kernels have numerical issues, provides a PR and accepted by human experts🤓
A fun small win for automated research:
We found and helped fix some edge cases that could affect inference performance in vLLM and SGLang.
In our last blog post, we described a reward hacking judge we developed for performance optimization tasks.
While applying the judge to some new autoresearch work, it discovered that some FlashInfer (a library underpinning vLLM and SGLang) kernels used a hard coded value of -50,000 as a masked-attention sentinel -- even though valid QK values can be smaller.
Corner cases like this that are numerically wrong but silent can cause a huge amount of headache to find and fix, e.g., the historical debate around flash attention (arxiv.org/abs/2405.02803).
Great use case for AI.
github.com/flashinfer-ai/fla…
赠Zeyuan Allen-Zhu🫡
世言大模惟精调,君执初心问真章。
动力学中观涨落,表达性里辨行藏。
万里独征云和月,所慕岂在功与赏。
他年若问登临处,格物致理照新航。
突き破れ、扉の向こうへ!
(source: 鋼の錬金術師 ED,《扉の向こうへ》)
I've decided it's time to resign from FAIR. 🫡
I'm especially grateful for the compute that made much of my research possible: 400 H100/200 GPUs allocated to me by FAIR; over a thousand H100s borrowed from FAIR Europe's CodeGen team led by Gabriel (@syhw ); thousands more borrowed from a legacy cluster in early 2025; and access to thousands of idle and low-prio GPUs across FAIR.
For clarity, since joining FAIR four years ago, I've been on FAIR-level pay throughout. I mention this simply to avoid any confusion in any media coverage.
Many thanks to @ylecun for founding FAIR, and to Joelle (@jpineau1 ) for steering FAIR through the later years of its golden age.
じゃあね — so long, FAIR.















