Founding AI Engineer, Developer Relations @Wandb @Coreweave 🐝✨ Content on Serverless Inference, Evals, Sandbox the stuff that’s actually moving right now

Joined January 2025
During @reflection_ai’s private preview of Beam, I built a haunted escape room to put its coding and reasoning to the test. I created a game called “Code Your Way Out”, and it's one room with three linked puzzles. Beam has to repair a brass orrery by lining its rings up with a constellation, route the light, then program its escape through a sealed hatch. Beam never sees the room. Each turn, it gets text observations and writes Python; the code runs in a @CoreWeave Sandbox, and the game engine validates every action before the explorer robot moves. Beam was out in about 30 seconds. Super bullish on this model and really excited to see builders get this model in their hands.
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Not ARC pleaseeee 2026 is rough enough as it is..
We've decided to sunset Arc on December 22, 2026. That's not an easy sentence to write. We spent years building Arc and celebrating each and every release along the way: we have so much pride and love for what we made alongside the Arc community. Our priority is to deliver best-in-class security for our members. Keeping a browser secure takes constant, dedicated work that is only increasing in the age of AI. Dia was built from the ground up to meet today’s security standards, so that's where our engineering and security teams will focus moving forward. We've worked to make switching to @diabrowser as easy as possible for Arc members. Here's how: · Your passwords, bookmarks, extensions and history come over to Dia seamlessly. · Spaces, Folders, and Tab Groups are in Dia and import over with your data intact. · Dia now surpasses Arc benchmarks in stability, speed, and security. · The browser features you use in Arc are free in Dia, and the AI is optional. Thank you for using Arc, for pushing us to make it better, and for building alongside us. The team that made Arc is the same team behind Dia, and some of our most ambitious work is just ahead. We'd love for you to be there with us when it lands.
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Lorenzo Porras retweeted
We've decided to sunset Arc on December 22, 2026. That's not an easy sentence to write. We spent years building Arc and celebrating each and every release along the way: we have so much pride and love for what we made alongside the Arc community. Our priority is to deliver best-in-class security for our members. Keeping a browser secure takes constant, dedicated work that is only increasing in the age of AI. Dia was built from the ground up to meet today’s security standards, so that's where our engineering and security teams will focus moving forward. We've worked to make switching to @diabrowser as easy as possible for Arc members. Here's how: · Your passwords, bookmarks, extensions and history come over to Dia seamlessly. · Spaces, Folders, and Tab Groups are in Dia and import over with your data intact. · Dia now surpasses Arc benchmarks in stability, speed, and security. · The browser features you use in Arc are free in Dia, and the AI is optional. Thank you for using Arc, for pushing us to make it better, and for building alongside us. The team that made Arc is the same team behind Dia, and some of our most ambitious work is just ahead. We'd love for you to be there with us when it lands.
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Ugh… i’ve used arc since the beginning… now i have to move.. ughhhh
We've decided to sunset Arc on December 22, 2026. That's not an easy sentence to write. We spent years building Arc and celebrating each and every release along the way: we have so much pride and love for what we made alongside the Arc community. Our priority is to deliver best-in-class security for our members. Keeping a browser secure takes constant, dedicated work that is only increasing in the age of AI. Dia was built from the ground up to meet today’s security standards, so that's where our engineering and security teams will focus moving forward. We've worked to make switching to @diabrowser as easy as possible for Arc members. Here's how: · Your passwords, bookmarks, extensions and history come over to Dia seamlessly. · Spaces, Folders, and Tab Groups are in Dia and import over with your data intact. · Dia now surpasses Arc benchmarks in stability, speed, and security. · The browser features you use in Arc are free in Dia, and the AI is optional. Thank you for using Arc, for pushing us to make it better, and for building alongside us. The team that made Arc is the same team behind Dia, and some of our most ambitious work is just ahead. We'd love for you to be there with us when it lands.
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Lorenzo Porras retweeted
We formally announced Mirendil less than 4 months ago. Today, I'm excited to share an important milestone for: Pretraining at scale without a pretraining team. Mirendil's mission is to solve Recursive Self-Improvement (RSI) and use it to democratize frontier AI development, ultimately accelerating science and technology. At Mirendil, when we think about RSI, we think holistically about the company as an intelligent entity that self-improves toward its goal. From that perspective, the most powerful notion of acceleration is reducing the time and resources (number of human experts, compute, and other costs) needed to achieve ambitious goals. Given that pretraining is perhaps the most important yet most challenging part of frontier AI development, we decided to run an ambitious controlled experiment: Starting fully from scratch, can we significantly reduce the time, number of human experts, and compute resources needed to go all the way to successfully pretraining a strong coding model at scale? Mirendil-Base is the result of this experiment. Our first pretrained model was built by one researcher in 3.5 months, with less than $10M in compute. This includes all the research and small-scale experiments it took to get there, as well as the final training run. The recipe holds up as the models get bigger. For reference, Mirendil-Base is in the 100B-500B parameter range, Mirendil-Base-Large in the 500B-2T range, and Mirendil-Base-XL in the 2T-10T range. We're beginning to see a world where a single researcher, empowered by AI, can take on work that once required an entire research organization. As these systems improve, the bottleneck shifts from the size of a team to the ambition and judgment of the people directing them. This has profound implications for who gets to build AI and, ultimately, who gets to push the frontiers of science and technology forward. We’ll share independent evaluations, post-training benchmarks and API-access sooner than you think so stay tuned!
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Lorenzo Porras retweeted
Auto-research on idle GPU capacity Every idle GPU is spice that isn't flowing. And the spice must flow. One idea to keep your GPUs busy is an auto-research pipeline: a queue of different ideas for agents to try whenever the GPUs are not doing higher priority work. On @CoreWeave you can build this from: - SUNK (Slurm on Kubernetes) to share nodes between priority jobs and agents, with preemption so priority work gets done
- GPU sandboxes to run agent-written code in isolation
- Spot capacity for cheap extra capacity 
- Dedicated inference plus Dynamo agent_hints to rank the agents' own model calls below production traffic And you can see what the agents are doing: traces, evals and training runs in one place.
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Lorenzo Porras retweeted
🔦 Beam, Reflection's first model with open weights, is live today on CoreWeave Serverless Inference. Call it through an API and leave the GPUs to us. We are also proud to share that @reflection_ai used @wandb in CoreWeave Forge during Beam's training. Developers in the private preview have been calling it fast and accurate, and they like that it doesn't ramble. See what @TheCodingSoup on our team built with private preview access below. Get started with Beam here: crwv.co/utuxk
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Its out! Try @reflection_ai Beam on @CoreWeave serverless inference! If you also get a chance check out the demo I built that is on the launch page, and pinned on my X as well!
🔦 Beam, Reflection's first model with open weights, is live today on CoreWeave Serverless Inference. Call it through an API and leave the GPUs to us. We are also proud to share that @reflection_ai used @wandb in CoreWeave Forge during Beam's training. Developers in the private preview have been calling it fast and accurate, and they like that it doesn't ramble. See what @TheCodingSoup on our team built with private preview access below. Get started with Beam here: crwv.co/utuxk
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👀👀👀
New model dropping soon on @CoreWeave Serverless Inference 👀 CoreWeave Agent Lens (@weave_wb) tracing built in.
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Interesting rundown of where benchmarking stands and what benchmaxxing actually looks like in practice.
Moritz Hardt thinks that OpenAI and Anthropic’s claims about benchmarks, which are used to test AI models’ capabilities, are misleading. But if the tests aren’t accurate, then how do we know how good the models really are? Read the interview: quantamagazine.org/he-wants-…
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Beam is a lot of fun to work with. Checkout my pinned post on how I used it for an escape room!
Beam is now available across platforms, with open weights under the Apache 2.0 license - in collaboration with an ecosystem of 40+ partners. We're releasing: - Weights, tokenizer, and reference implementation - BF16, FP8 and NVFP4 weights and a DFlash2 drafter - The open source harness we built and trained Beam on: Mirror CLI Weights and model card on Hugging Face: huggingface.co/reflection
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Beam is now available across platforms, with open weights under the Apache 2.0 license - in collaboration with an ecosystem of 40+ partners. We're releasing: - Weights, tokenizer, and reference implementation - BF16, FP8 and NVFP4 weights and a DFlash2 drafter - The open source harness we built and trained Beam on: Mirror CLI Weights and model card on Hugging Face: huggingface.co/reflection
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Lorenzo Porras retweeted
Beam is now available across platforms, with open weights under the Apache 2.0 license - in collaboration with an ecosystem of 40+ partners. We're releasing: - Weights, tokenizer, and reference implementation - BF16, FP8 and NVFP4 weights and a DFlash2 drafter - The open source harness we built and trained Beam on: Mirror CLI Weights and model card on Hugging Face: huggingface.co/reflection
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Lorenzo Porras retweeted
Beam weights have dropped along with incredible ecosystem support! What are you going to build with Beam! Lessgo! 🚀🚀🚀🚀
Beam is now available across platforms, with open weights under the Apache 2.0 license - in collaboration with an ecosystem of 40+ partners. We're releasing: - Weights, tokenizer, and reference implementation - BF16, FP8 and NVFP4 weights and a DFlash2 drafter - The open source harness we built and trained Beam on: Mirror CLI Weights and model card on Hugging Face: huggingface.co/reflection
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Lorenzo Porras retweeted
Today we’re releasing Muse Spark Open, the most capable US open-weight model to date. Built for coding and agentic work, it excels at long-horizon tasks, complex software engineering, and multi-step reasoning. Key Model Specs: → 816B total / 42B active parameters → 1M token context window → Natively multimodal across text, image, video, audio
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Finally... 😭😭😭 I'm so sick of juggling sessions across 10 terminal tabs with zero idea what's running where side by side might actually make the desktop app usable.
We've been working hard on making the Claude Code desktop app great for running lots of sessions side by side. It's now much quicker to start sessions, easier to split work across a few, and you can always see what each of them is doing. Here’s what's new:
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And yet another model releases 👀
We are releasing Ultramarine 1 Flash, a frontier-class model built for knowledge work. It is open-source and achieves similar performance to Fable 5, while being 60x cheaper. It was post-trained by a team of 5 for ~$300k all-in. Available on API now, with weights releasing in 2 weeks.
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Gave an AI five functions and a tiny island. It walked into a hole. Now it has to collect the gems, build the bridge, and reach the portal. Running on @CoreWeave Sandbox: one deploy script, a public endpoint, set to stay up for 30 days. 8765-aec58cb9-9d65-4e5e-ace7… Which model would you try? 👇
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Lorenzo Porras retweeted
Just handoff all your agent sessions to a cloud sandbox with 'cws-agent handoff'. This has saved me many times on long sessions that I wanted to continue working on as I left the house. Close that laptop!
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Trying out @Meta @Muse for the first time. I’ve not had an AI personal assistant before and heard great things. Really enjoying it so far, setting up goals, prepping content, fitness goals as well. I need to find more ways to make this useful! Any suggestions??
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