
Building SkyRL at @BerkeleySky Join the Slack community: https://xitter.cf/t.co/mSO97T61vR
Berkeley, California
Joined January 2025
- Tweets179
- Following18
- Followers2.9K
- Likes302
Great to see @modal launch this! You can also deploy a Tinker endpoint directly on AWS EC2 with SkyRL @NovaSkyAI for the same cost and flexibility benefits, and start agentic RL training with our AgentCore RL Toolkit! github.com/awslabs/agentcore…
Tinker changed how people do post-training. We're big fans, and so are many of the teams we work with. But as those teams scale up, they keep raising the same two problems: per-token pricing gets expensive quickly, and you’re limited to the models and features the provider decides to support.
We think a good API deserves more than one implementation.
Today we're releasing Spindle, an open-source, Tinker-compatible training server that runs in your Modal workspace. Your existing Tinker scripts run unchanged, and because you own the server, you pay for GPU time instead of tokens.
NovaSky retweeted

Qiuyang Mang@MangQiuyang11h
United States
United StatesConnected via China App StoreAccount-level information, not a live location or per-post device.
FrontierCS 2 is our new benchmark for CS research & development.
Each task is based on a paper: we delete the contribution from the released code, and ask agents to outdo the original method, as judged by the authors' chosen metrics. Agents don't have access to the paper or web.
NovaSky retweeted
Post-training a 4B model with RL to fly Tesla Roadster. It outperforms recent open models and even GPT-6 Astra in a storm.
The key: have the model learn from the teachers first and then learn itself in practice.
Trained with SkyRL (@NovaSkyAI) and vLLM (@vllm_project), orchestrated by SkyPilot's Job Group (@skypilot_org).
Check it out ⬇️
Tesla's flying Roadster went viral. The real demo had been delayed two weeks "due to high winds."
We asked: could the latest LLMs sit in the pilot's seat and fly the car through that wind?
We built an RL environment for LLMs to fly it. In real time, GPT-6 Astra, DeepSeek, Muse Spark Open, Beam and Nemotron 3.5 Super VL landed 0% of kickflips.
Even with unlimited time to think for each decision, they still did worse than a Qwen 4B model we post-trained with RL in a storm.
NovaSky retweeted
Super excited to share some of the work I’ve been doing on supporting 1M token context training on SkyRL for GLM 5.3 Flash, 64x higher than the out of the box Megatron baseline! 🚀
This work was done in collaboration with the amazing folks at @LilaSciences! 🤩
Getting there took key algorithmic and systems optimizations in four main areas:
1) DeepSeek Sparse Attention: run DSA on a sparse kernel; chunk and shard its quadratic indexer.
2) Activation recompute and offloading: recompute activations in backward and offload saved inputs to CPU.
3) Context parallelism: split each sequence across GPUs, with new CP support for KDA and a fix for DSA.
4) Avoiding unnecessary precision upcasts: keep FP32 copies out of memory and off the network.
For more details on our implementations and our results, check out our full technical blog here: blog.skyrl.ai/blog/1m-contex…!
This work benefited from the contributions of many people along the way. Big thanks to @pcmoritz, @erictang000, @sumanthrh, @CyrusHakha, @richliaw from @anyscalecompute and Keith Truongcao, Tushar Khot, Vivek Subramanian, Semih Kara from Lila Sciences for all the help and guidance!
NovaSky retweeted
Check our blog: skypilot.ai/blog/flying-road…
Trained with SkyRL (@NovaSkyAI), served with vLLM (@vllm_project), and orchestrated with SkyPilot (@skypilot_org)
NovaSky retweeted
Tesla's flying Roadster went viral. The real demo had been delayed two weeks "due to high winds."
We asked: could the latest LLMs sit in the pilot's seat and fly the car through that wind?
We built an RL environment for LLMs to fly it. In real time, GPT-6 Astra, DeepSeek, Muse Spark Open, Beam and Nemotron 3.5 Super VL landed 0% of kickflips.
Even with unlimited time to think for each decision, they still did worse than a Qwen 4B model we post-trained with RL in a storm.
NovaSky retweeted

Reflection@reflection_aiOct 21
United States
United StatesConnected via WebAccount-level information, not a live location or per-post device.
Model customization recipes are live on our website and in the cookbook repo.
Beam is now supported across RL and SFT stacks including @axolotl_ai, NeMo RL, NeMo AutoModel, Megatron Bridge (@NVIDIAAI), Miles (@radixark), SkyRL (@NovaSkyAI), and TRL (@huggingface).
Get cooking 🧑🍳
developers.reflection.ai/cus…
NovaSky retweeted
First day 0 model support on SkyRL. Great work from @sumanthrh !
NovaSky retweeted
🎉 Day-0 RL support for Beam in SkyRL @NovaSkyAI.
LoRA, BF16 full fine-tuning and MXFP8 RL, with vLLM rollouts and Reflection’s Megatron-Bridge implementation.
SkyRL reports +62% LoRA decode throughput from right-sizing expert adapters in vLLM: 276 → 447 tok/s/GPU at 32 concurrent requests, PP2×TP8. This is a decode result, not an end-to-end training speedup.
R3 works with pipeline parallelism, and FP32 router weights are preserved during weight sync. Thanks to Sumanth Hegde and the SkyRL team!
docs.skyrl.ai
NovaSky retweeted
Great to see this out!
Datadog's new SOTA model for investigating production incidents. Their in-house training stack builds on top of SkyRL! 🚀🚀🚀
Meet Scout 1.0, our first AI model built for investigating production incidents.
Scout matches frontier-model investigation quality at a fraction of the cost, which makes it practical to investigate more issues, earlier.
We trained Scout on realistic simulations built from real-world incidents and production telemetry, using reinforcement learning to reward accurate root causes backed by evidence.
Learn more and sign up for the preview: bit.ly/3TJknGO
NovaSky retweeted
datadog ai research used SkyRL to post-train GLM 5.3 Flash to perform at the pareto frontier for their SRE eval
@bthecohen and team were some of the earliest users of SkyRL at scale, really cool to see these results finally out! great tech report as well
Meet Scout 1.0, our first AI model built for investigating production incidents.
Scout matches frontier-model investigation quality at a fraction of the cost, which makes it practical to investigate more issues, earlier.
We trained Scout on realistic simulations built from real-world incidents and production telemetry, using reinforcement learning to reward accurate root causes backed by evidence.
Learn more and sign up for the preview: bit.ly/3TJknGO
NovaSky retweeted
Datadog post-trained GLM-5.3 Flash via RL on real-incident sims. Matches frontier SRE performance at much lower cost.
Their RL stack is built on top of SkyRL! Check out the technical report web-assets.dd-static.net/425…
Meet Scout 1.0, our first AI model built for investigating production incidents.
Scout matches frontier-model investigation quality at a fraction of the cost, which makes it practical to investigate more issues, earlier.
We trained Scout on realistic simulations built from real-world incidents and production telemetry, using reinforcement learning to reward accurate root causes backed by evidence.
Learn more and sign up for the preview: bit.ly/3TJknGO
NovaSky retweeted
Post-trained with SkyRL!
We were able to fine tune an open weight model (Qwen3.5-9B) on proprietary internal data at @coinbase, and it out performed frontier models, at much lower cost and speed, for a specialized task (fraud prevention in this case).
I think we'll see more of this pattern inside companies. The frontier models are amazing generalists. But increasingly you'll see specialist models out perform on more narrow tasks, either working on teams, or by themselves.
We're making it easy to fine tune models internally for our employees. We even have a skill for it in our internal harness that makes it easy to spin these up and start training them:
"/fine-tune-and-serve-llm I want to fine-tune Qwen for payments risk review. help me get started"
I imagine we'll have some backend services that could be replaced entirely by this new architecture.
NovaSky retweeted
Post-trained with SkyRL @NovaSkyAI
Served on Ray Serve LLM @raydistributed
all on Anyscale Platform @anyscalecompute
We were able to fine tune an open weight model (Qwen3.5-9B) on proprietary internal data at @coinbase, and it out performed frontier models, at much lower cost and speed, for a specialized task (fraud prevention in this case).
I think we'll see more of this pattern inside companies. The frontier models are amazing generalists. But increasingly you'll see specialist models out perform on more narrow tasks, either working on teams, or by themselves.
We're making it easy to fine tune models internally for our employees. We even have a skill for it in our internal harness that makes it easy to spin these up and start training them:
"/fine-tune-and-serve-llm I want to fine-tune Qwen for payments risk review. help me get started"
I imagine we'll have some backend services that could be replaced entirely by this new architecture.
NovaSky retweeted
Read more about our experiment using SkyRL here: afterquery.com/blog/improvin…
To learn more about our tasks and reward design, reach out to us at [email protected]
NovaSky retweeted
Kimi K2.5-2.7 can be trained with RL on just 16 B300 GPUs (yes, just 2 nodes!) with full context
Most post-training frameworks out there will tell you that you need 16 full nodes, and might not even give you full context
Thanks to SkyRL maintainers for collab
Excited to announce the release of SkyRL v0.4.0!
Some highlights:
- Support for GLM 5.3 Flash, GLM 5.3, and Kimi K2.7
- Top-P sampler replay and optimized R3 data transfer
- Full FP8/MXFP8 RL
- Sharded P2P weight transfer
Blog: blog.skyrl.ai/blog/skyrl-v0-…
Details in 🧵
NovaSky retweeted
Excited to announce the release of SkyRL v0.4.0!
Some highlights:
- Support for GLM 5.3 Flash, GLM 5.3, and Kimi K2.7
- Top-P sampler replay and optimized R3 data transfer
- Full FP8/MXFP8 RL
- Sharded P2P weight transfer
Blog: blog.skyrl.ai/blog/skyrl-v0-…
Details in 🧵
NovaSky retweeted
How does one RL post-train a 397B model for long-horizon knowledge work? 👩💼
We share every step we took to bring Qwen 3.5 397B from 16.1% Pass@1 to 27.3% on APEX-Agents using DPPO, including final models weights and the full training script🚀 This is the first of many works from Mercor Research on open model training research.
Full blog: mercor.com/blog/training-fro…
Source code: github.com/Mercor-Intelligen…
NovaSky retweeted
Worked with Mercor Research and the SkyRL team, training Qwen3.5-397B-A17B on APEX-Agents (long-horizon office work) off-the-shelf data with SkyRL, improving Pass@1 from 16% to 27%.
The post is more of a practical field guide for what to do given an RL dataset, de-risking step by step: environment infra, harness fixes/optimizations, token-in-token-out, an overfitting run, small-model ablations, then the hero run.
We were also delighted to see the gains transfer to OpenCode despite training on an MCP-based harness, and even to Terminal-Bench 2.1.
Code, models, and eval traces are all open source. Hope it helps your next hillclimb!

























