edunteman
edunteman on Hacker News
Nice work! Had to do similar serverside for stripping named entities and ended up burning way too much LLM cash
I hate to be that guy, but you can just choose to do these things. Learn to set SMART goals. Then set just one, so there's no excuses around priorities. Obviously, choose well. Make that goal your life.
I’ve been a big fan of “what’s the thinnest this could be” interpretations of sandboxes. This is a great example of that. On the other end of the spectrum there’s just-bash from the Vercel folks.
The llm detector in my brain went off too
Your repo was actually a major point of reference! Thank you for open sourcing it. Ironically when I first got into zig I built a similar generator for python bridging which your project reminded me of
https://github.com/erik-dunteman/zigpyUltimate decision for not using a bindings generator was primarily to deeply understand NAPI.
Exactly, that’d be the intention. For compute-heavy or long running jobs you’d still probably want a dedicated VM like on E2B but for quick stuff, bVisor
Correct, your PATH resolves to your local tools as if it was unprotected bash, but syscalls are filtered/virtualized
Hell yeah, love to hear it! Happy to answer any questions or issues you run into
Posted by
edunteman on Monday February 23, 2026 @12:56PM
from the show-hn dept.
https://github.com/butter-dot-dev/bVisor
bVisor is an SDK and runtime for safely executing bash commands directly on your host machine. We built it on the belief that "sandbox" doesn't need to mean shipping off to remote sandbox products, or spinning up local VMs / containers. Sometimes, you just want to run that bash command locally.bVisor boots a sandbox from user-space without special permissions, powered by seccomp user notifier....
The part that most resonates with me is the lingering feeling of “oh but it must be my fault for underspecifying” which blocks the outright belief that models are just still sloppy at certain things
Posted by
edunteman on Thursday November 27, 2025 @02:23PM
from the cookwithbutter.com dept.
Good question, I imagine you’d need to set up an ngrok endpoint to tunnel to local LLMs.
In those cases perhaps an open source (maybe even local) version would make more sense. For our hosted version we’d need to charge something, given storage requirements to run such a service, but especially for local models that feels wrong. I’ve been considering open source for this reason.
Ah yes that makes sense, have heard of those cases too but hadn’t put much thought into it. Thanks for pointing it out!
I’d love your opinion here!
Right now, we assume first call is correct, and will eagerly take the first match we find while traversing the tree.
One of the worst things that could currently happen is we cache a bad run, and now instead of occasional failures you’re given 100% failures.
A few approaches we’ve considered
- maintain a staging tree, and only promote to live if multiple sibling nodes (messages) look similar enough. Decision to promote could be via tempting, regex, fuzzy, semantic, or LLM-judged
- add some feedback APIs for a client to score end-to-end runs so that path could develop some reputation
Awesome to hear you’ve done similar. JSON artifacts from runs seem to be a common approach for building this in house, similar to what we did with the muscle mem. Detecting cache misses is a bit hard without seeing what the model sees, part of what inspired this proxy direction.
Thanks for the nice words!
I feel the same - we’ll use it as long as we can since it’s customer aligned but I wouldn’t be surprised if competitive or COGs costs force us to change in the future.
It’s bring-your-own-key, so any calls proxied to OpenAI just end up billing directly to your account as normal.
You’d only pay Butter for calls that don’t go to the provider. That’d be a separate billing account with butter.
I couldn’t see how it wouldn’t be, as it’s a free market opt-in decision to use Butter
Posted by
edunteman on Tuesday October 28, 2025 @03:39PM
from the show-hn dept.
https://www.butter.dev/
Hi HN! I'm Erik. We built Butter, an LLM proxy that makes agent systems deterministic by caching and replaying responses, so automations behave consistently across runs.- It’s a chat completions compatible endpoint, making it easy to drop into existing agents with a custom base_url- The cache is template-aware, meaning lookups can treat dynamic content (names, addresses, etc.) as variablesYou...
Posted by
edunteman on Thursday October 23, 2025 @04:44PM
from the blog.butter.dev dept.
I've got a blog on this from the launch of Muscle Mem, which should paint a better picture
https://erikdunteman.com/blog/muscle-memComputer use agents (as an RPA alternative) is the easiest example to reach to: UIs change but not often, so the "trajectory" of click and key entry tool calls is mostly fixed over time and worth feeding to the agent as a canned trajectory. I discuss the flaws of computer use and RPA in the blog above.
A counterexample is coding agents: it's a deeply user-interractive workflow reading from a codebase that's evolving. So the set of things the model is inferencing on is always different, and trajectories are never repeated.
Hope this helps
Thanks! For langchain you can repoint your base_url in the client. Autogpt I'm not as familiar with. Closed loop robotics using LLMs may be a stretch for now, especially since vision is a heavy component, but theoretically the patterns baked into small language models running on-device or hosted LLMs at higher level planning loops, could be emulated by a butter cache if observed in high enough volume.
An interesting alternative product to offer is injecting prompt cache tokens into requests where they could be helpful; not bypassing generations but at least low hanging fruit for cost savings
Posted by
edunteman on Wednesday October 01, 2025 @03:29PM
from the show-hn dept.
https://docs.butter.dev
Hi HN, Erik here. Today we launch Butter, an OpenAI-compatible API proxy that caches LLM generations and serves them deterministically on revisit.Since April, we’ve been working on this concept of “muscle memory,” or deterministic replay, for agent systems performing automations. You may recall our first post in May, launching a python package called Muscle...
I'd argue that understanding disassembled assembly could be considered reverse engineering, which would logically extend to source code unless we draw the line at compilation
Love your sleep time stuff! It's an inspiration for Muscle Mem
Great to see you here :) thanks for the kind words!
totally follows! thanks for sharing, will noodle on it
Definitely, but there's lots of API surface area to figure out first, so will stick strictly to python for now. I can see a future where this ends up with a native storage/query core and with python/js bindings on top.