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Composer: Building a fast frontier model with RL

cursor.com

61–70 of 169 posts

Re: Composer: Building a fast frontier model with RL

#61
post #50

Earlier quoted context omitted.

We did a lot of internal testing and thought this model was already quite useful for release.

Makes sense! I like that you guys are more open about it. The other labs just drop stuff from the ivory tower. I think your style matches better with engineers who are used to datasheets etc. and usually don't like poking a black box

Thanks! I do like the labs blog posts as well though, OpenAI and Anthropic have some classics.

Re: Composer: Building a fast frontier model with RL

#62
post #48
post #45

Earlier quoted context omitted.

Is it true that Cheetah is Grok Code Fast 2? Does this mean that the new Cursor model is also based on Grok?

Cheetah was an earlier (and dumber) version of this model that we used to test production speed. They are both developed in-house. If you liked Cheetah, give this model a try.

Awesome, thanks for the clarification. So are the rumors around Cheetah being based on a Grok model just straight up untrue? I want to try Composer but have a pretty strict no X/Grok policy.

Re: Composer: Building a fast frontier model with RL

#63
post #56
post #51

Earlier quoted context omitted.

is Composer a fine tune of an existing open source base model?

Our primary focus is on RL post-training. We think that is the best way to get the model to be a strong interactive agent.

So, yes, but you won’t say what the base model is? :)

Re: Composer: Building a fast frontier model with RL

#64
post #16

Hi everyone, I am an ML researcher at Cursor, and worked on this project. Would love to hear any feedback you may have on the model, and can answer question about the blog post.

Which model did you distill it from? Great work! PS getting a few scenarios where it doesn't follow rules as well as sonnet 4.5

The blog talks about the training process. Specifically we trained with RL post-training on coding examples.

Re: Composer: Building a fast frontier model with RL

#66

Could anyone explain how to use multiple agents and subagents in Cursor, Claude Code, or others? It is already challenging to me taming one model doing work, let alone synchronizing multiple parallel workers. Do you have to split the plan in parallelizable tasks that could be worked in parallel in one codebase without breaking and confusing the other agents?

you can use git worktrees and just have multiple Claude Code terminal instances working on each worktree. That way they don't clash, just delete the worktree when the task is done.

Re: Composer: Building a fast frontier model with RL

#67

People on here love to be contrarian about Cursor, but I’ve tried all the popular alternatives (Copilot, Claude Code, Codex, Gemini CLI, Cline) and found Cursor’s overall experience to just be unmatched. A big part of that is its speed, another its reliability. It’s the only coding agent I’m actually really motivated to use out of the box because it really does make me feel more productive while the others keep messi…

You tried Claude and still prefer cursor?

Absolutely. I actually don’t understand the preference folks have for Claude code. I don’t find it that powerful. That said, I think some of it comes down to preference and work context.

Re: Composer: Building a fast frontier model with RL

#68

Earlier quoted context omitted.

You tried Claude and still prefer cursor?

Absolutely. CC can be tuned to not do too much crap on its own, but even with the new extension its IDE integration and multi thread management are still significantly worse, as is its status reporting, which I find to be very important. Also, somehow magically, I’ve found Cursor’s Auto mode to be significantly faster than the specific models I’ve tried, Claude being among them.

Auto is pretty amazing and I think most folks that have issues or complain about cost are simply not using Auto.

Re: Composer: Building a fast frontier model with RL

#69
post #47

Maybe I'm an outlier but Sonnet 4.5 quality is about as low as I'm willing to go. It's generation speed is not the problem or the time sink. It's wrestling with it to get the right output. --- And just to clarify as maybe I misunderstood again but people are comparing cursor to Claude Code and codex etc here- isn't this whole article all cursor just using different models?

There’s two different kinds of users, on one side people are more hands off and want the model to autonomously handle longer tasks on its own with minimal guidance, and on the other side is users who want to interactively collaborate with the model to produce desired results. Speed matters much more for the second case, where you know what you want and just want the model to implement whatever you had in mind as quic…

I'm very solidly in the second group - but I review all the code. If it writes faster than I can read, that's fast enough.

Re: Composer: Building a fast frontier model with RL

#70

People on here love to be contrarian about Cursor, but I’ve tried all the popular alternatives (Copilot, Claude Code, Codex, Gemini CLI, Cline) and found Cursor’s overall experience to just be unmatched. A big part of that is its speed, another its reliability. It’s the only coding agent I’m actually really motivated to use out of the box because it really does make me feel more productive while the others keep messi…

I too have tried them all and have settled with Cursor being the best. That said I see the current space split between folks like me who know generally what I want built and appreciate a tool that helps me get to goal quicker and on the otherwise of the spectrum, folks who want the tool to orchestrate most of the engineering. I have no opinion on which is better but for me I sit on the first camp. In that camp Cursor is by far the best tool.
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