CS PhD @UCBerkeley Sky Lab 🐻 Systems & AI & Sustainability 🌍 Prev: @google, @ibm, @CarnegieMellon🐕‍🦺, @UofT🇨🇦

Berkeley
Does your Claude model really need Claude Code…? 🤔 We evaluate 7 models on Claude Code, Codex, and Pi. Three surprising findings emerge: 1️⃣Harness choice has little effect on task success rate, but can significantly affect the cost 2️⃣A simple harness can be competitive 3️⃣The native harness isn’t always the best. Millions of people are using coding agents, but the impact of harness choice remains unclear. (1/n) More details in the thread. 🧵
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SkyDiscover // @shulynnliu, @mertcemri, @shagarw21, @AlexKrentsel (@UCBerkeley) — An open-source framework that uses AI to discover better algorithms and assemble complete systems from a specification.
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Superintelligence should benefit human intelligence. Mathematics is our starting point. We’re launching Readable Intelligence, and we invite the math and AI communities to build it with us. 📄 Pick a paper. 💬 Flag an unclear step. 🙌 Contribute a more readable version.... readable-intelligence.com/
OpenAI released 722 math manuscripts in a day. Will mathematicians read them? A proof can settle a question. Understanding it can open up a thousand more. Introducing Readable Intelligence: making AI-generated math easier to understand and build on. readable-intelligence.com/
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Got a free 5080 from Nvidia’s BAIR & SKY research panel today!!! THANK YOU @nvidia! First time in my life to win in a raffle 🥹 Time to setup an always-on FreeToken server on this 5080 😁🫶🙌
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unironically i wore a leather jacket today, maybe that's why i got blessed by the god of leather jacket 🫡🫡🫡
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While exploring diffusion language models (DLMs), we kept asking ourselves: given speculative decoding, a lossless acceleration technique, why do we still need DLMs? 🤔 Our latest work, ORL, tries to answer this question: AR optimizes intelligence 👆, speculative decoding optimizes speed 👉, and DLMs optimize the Pareto frontier of speed and intelligence 🚀. Through co-design across the algorithms, the training and inference engine, and the kernels, ORL pushes out a new Pareto frontier of intelligence and speed. Similar performance, much faster than speculative decoding. You say lossy spec? ORL-DLM is better too! 😎 🌐 Project + live demos: introspective-diffusion.gith…
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🚀 Excited to introduce 𝐃𝐮𝐨𝐃𝐢𝐬𝐜𝐨𝐯𝐞𝐫! This isn’t benchmark gaming. It’s AI agents shipping real PRs and beating human-expert hardware baselines. 🔥 𝐓𝐡𝐞 𝐛𝐫𝐞𝐚𝐤𝐭𝐡𝐫𝐨𝐮𝐠𝐡𝐬 🚀 🛠️ Real optimizations merged into main branches (e.g., FreeToken #619) 🧠 First superhuman CPU prefetcher: +3.93% | +6.31% overall, outperforming AlphaEvolve ⚡ 2.68× TPU kernel speedup | 1.92× faster vLLM serving | 🏆 #1 on NVIDIA SOL-ExecBench (B200) 💡 𝐓𝐡𝐞 𝐬𝐞𝐜𝐫𝐞𝐭 𝐬𝐚𝐮𝐜𝐞? Agents co-discover fast evaluation proxies (“yardsticks”) to slash slow eval bottlenecks and compound real performance gains at scale. 🤝 Incredible collaboration across @GoogleCloud, @BerkeleySky & @StanfordAILab! 🔥 We’re pushing the frontier of AI-driven systems optimization. And we’re just getting started. 🚀
AI is cracking math problems. What's holding it back in engineering? The cost of evaluation. Agents can generate ideas in seconds, but testing them can take hours or days. 💡 Meet DuoDiscover: where evaluation is part of what agents discover 👇🧵 Some highlights: 🏆 #1 on NVIDIA's SOL-ExecBench 🐍 2× the experts on SWE-fficiency 🚀 1.92× on vLLM; 1.44× on FreeToken 🔥 2.68× over production TPU kernels 🖥️ Beats the best human and AI-designed CPU prefetchers

ALT Alt text: Animated explainer. Opens with the DuoDiscover title card, authors and institutions. The task: make a big codebase run faster. Shows why true evaluations are slow, about 85 minutes for vLLM, then DuoDiscover's three mechanisms. Mechanism 1, co-discover a target and its yardstick: an agent picks what to optimize and builds a yardstick, a fast proxy evaluator that scores edits in seconds. Mechanism 2, keep the yardstick honest: a drifting yardstick is caught by a fidelity test and invalidated. Mechanism 3, scale as a bottom-up fleet: agents each pick their own target while a lightweight orchestrator spawns, terminates, briefs and seeds agents with confirmed work. Ends with results highlights, the DuoDiscover logo and a QR code linking to the paper, with Google, UC Berkeley and Stanford.

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Do AI harnesses matter? Yes, KISS Sorcar outperforms three coding harnesses on Terminal-Bench 2.0. On Terminal-Bench 2.0, KISS Sorcar (github.com/ksenxx/kiss_ai) solved 75.6% of attempts across seven models, the best rate on every model against Pi (70.0%), Codex CLI (65.7%), and Claude Code (65.1%), and in a paired rerun against Pi on Claude Fable 5, it won 80.0% to 68.9% at about the same cost per attempt. The three harness numbers come from the study below by @melissapan et al. We ran KISS Sorcar on the same 30 tasks and seven models, three attempts per task. We reran the Pi experiments: same tasks and prices, no turn cap for either agent, Pi at high effort with no budget cap. Pi cost $1.45 per attempt and KISS Sorcar $1.50; the gap was 11 points, paired with p = 0.016. On the 59 tasks the study didn't sample, KISS Sorcar solved 79.1%, and a second Pi rerun on 57 of them (two sat out because a dead package mirror broke the verifier) came out to 82.5% vs. 71.9%, a 10.5-point gap with p = 0.008, at 63 cents more per attempt. Two reruns on one model don't settle it, but on this benchmark the harness seems to matter more than the study's three harnesses showed. Full table and intervals: kisssorcar.github.io/blog/ha…
Does your Claude model really need Claude Code…? 🤔 We evaluate 7 models on Claude Code, Codex, and Pi. Three surprising findings emerge: 1️⃣Harness choice has little effect on task success rate, but can significantly affect the cost 2️⃣A simple harness can be competitive 3️⃣The native harness isn’t always the best. Millions of people are using coding agents, but the impact of harness choice remains unclear. (1/n) More details in the thread. 🧵
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Releasing FLAT: Flash Linear Attention on TPUs 🚀 Pallas training kernels for Linear Attention, Mamba-2 and GLA. On one TPU v6e, forward + backward is up to 3x faster than FLA on an H100 for GLA, and 1.5x faster for Mamba-2. 🧵
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Test time recovery 🤩 Glad to see community’s work in agent failures inspired by MAST! Congrats for the cool work!
Excited to share our latest work on LLM agent failure recovery, led by @Changxiu_leo_ji and @Amylzx0828! 🧵 Core insight: Failure knowledge is conditional knowledge. Injecting it unconditionally can backfire. How and when it reaches the agent matters just as much as what it contains. 💡 This work is inspired by research in failure analysis (e.g. MAST from @mertcemri @melissapan) and in agent memory/learning from experience (e.g. ACE). Paper & details below 👇
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Video generation now runs right on your laptop. 🎬 Introducing FreeVideo — bringing MiniMax H3 + Video DeltaNet to the hardware you already own. As little as 8GB VRAM + 16GB RAM. ComfyUI integration, LoRAs & custom workflows. Code: github.com/FlashML-org/FreeV…
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AI systems should be designed for AI. If prefix caching gets in the way of free context access, we can fix the caching. This is the idea behind our Suffix Cache Reuse (SCR) for CLR serving. Check out our blogpost for details (fun visuals included)! wai-org.com/blog/clm/ Maybe the next step is to give CLMs direct agency over the cache itself. I’m excited to see what more creative and adaptive cache-aware context management could look like. It's also a good time to follow our account @waiorg , a student org we created to share our work on agents. Currently covering: TMax, CLM.
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🧵 More stable PPO for LLM post-training. Introducing EasyPPO: just fix the critic. ❌ No new actor loss ❌ No new policy algorithm ✅ Actor update unchanged EasyPPO delivers better results with zero training collapse across all our experiments.
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Quick intro video on 💰HarnessTax💰 is out!! I also shared some thoughts on what it means for our community to be aware of such cost in coding agents at the end!
Claude Code vs Codex vs Pi: which coding agent wins? @melissapan, PhD candidate at UC Berkeley’s Sky Computing Lab and previous @arena intern, explored the hidden “harness tax”: how the system surrounding an AI model affects its cost and performance. She reports three surprising findings. One: harness choice impacts cost more than accuracy. To learn about all three findings, and what they mean for building useful coding agents on realistic budgets, check out the full video here: piped.video/4R8qZGtEnAE
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Check out the blog post for full details -
Replying to @melissapan
More details in the blog post. 📄 harnesstax.github.io/ We as the community should evaluate and select the model AND the harness together. (6/n)
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Melissa Pan retweeted
Claude Code vs Codex vs Pi: which coding agent wins? @melissapan, PhD candidate at UC Berkeley’s Sky Computing Lab and previous @arena intern, explored the hidden “harness tax”: how the system surrounding an AI model affects its cost and performance. She reports three surprising findings. One: harness choice impacts cost more than accuracy. To learn about all three findings, and what they mean for building useful coding agents on realistic budgets, check out the full video here: piped.video/4R8qZGtEnAE
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Wrote a short blog about the "shape" of language models, and the tradeoffs they may present in the future. I genuinely think it's a valuable research direction to start thinking about now, especially w.r.t. harness design. alexzhang13.github.io/blog/2…
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yayy I can finally use dashes again - I love to write with dashes pre llm 😛
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Formal verification × agents 🚀 Our IDS paper was accepted as a NeurIPS oral! We study how agents can co-evolve code + proofs, achieving 3x the success rate of Claude Code on distributed systems specs. IDS Paper: arxiv.org/abs/2605.23109 Code: github.com/skydiscover-ai/sk… And also check out our recent work on the next challenge: ensuring the spec itself captures human intent. 👇 nitter.siddz.com/istoica05/status/21009…
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jev for semantic operators is a great example of how LLM data processing at scale requires rethinking across the stack, model architecture and learning algs included new work and many more thoughts on this coming soon 👀 in the meantime, check out lotus, star and stay tuned (link below)
Replying to @ericmao
I borrowed a ton of concepts from the lotus paper. The idea was well ahead of its time. Credit to the core contributors: @lianapatel_ @sid_jha1 @pgasawa @melissapan Harshit Gupta
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