just-bash

The back and forth between writing tools in javascript and go or rust seems like it's in an unstable equilibrium right now: - Go / Rust: It's easier than ever to rewrite existing tools in more performand languages - Javascript: The v8 runtime for vercel or cloudflare workers is a much cheaper way to run certain workloads (e.g. conversational agents) than running a heavy weight vm. See just bash as another example project for taking advantage of this (https://github.com/vercel-labs/just-bash) I'm curious to see what happens!

I thought it would be bash+fuse but it's actually running in the matrix: simulated bash in Elixir ported from Vercel's just-bash: > A virtual bash environment with an in-memory filesystem, written in TypeScript and designed for AI agents. >Broad support for standard unix commands and bash syntax with optional curl, Python, JS/TS, and sqlite support. https://github.com/vercel-labs/just-bash/tree/main/packages/... See also (credited by TFA): https://vercel.com/blog/how-to-build-agents-with-filesystems...

Does it work in just-bash? https://github.com/vercel-labs/just-bash/blob/main/packages/...

Coding agents spend a lot of time in the shell. When exploring a codebase, they usually reach for the same handful of tools: grep, find, ls, cat. We built a public SSH server that hosts Supabase docs as markdown files so that agents can explore them the same way they explore code: ssh supabase.sh grep -rl 'RLS' docs ssh supabase.sh cat docs/guides/database/postgres/row-level-security.md | head -10 Under the hood commands run inside Vercel's just-bash [1] library - an emulated bash shell sandboxed within the JS runtime. It uses a VFS where the docs are mounted as markdown files. SSH is handled by ssh2 [2]. Next step is evals to confirm whether or not this truly performs better than other knowledge retrieval methods (like skills, web search, MCP tools), but we were too excited not to share something now. [1] https://github.com/vercel-labs/j

> Well, there it is, the dumbest thing I'll read on the internet all week. Rude. In case you're open to learning, here's why I think this is useful. The big lesson we've learned from Claude Code, Codex CLI et al over the past twelve months is that the most useful tool you can provide to an LLM is Bash. Last year there was enormous buzz around MCP - Model Context Protocol. The idea was to provide a standard for wiring tools into LLMs, then thousands of such tools could bloom. Claude Code demonstrated that a single tool - Bash - is actually much more interesting than dozens of specialized tools. Want to edit files without rewriting the whole thing every time? Tell the agent to use sed or perl -e or python -c. Look at the whole Skills idea. The way Skills work is you tell the LLM "if you need to create an Excel spreadsheet, go read this mark

I somehow agree with this but want to add my two cents here. Cloudflare's Codemode[0] is a great "replacement" for MCP because AI is trained for writing code and handling errors. But it also doesn't fix security and sandboxing. For CLI and file operations we have Vercel's just-bash[1] but for everything else there is no safe solution. Therefore MCP still makes sense until somebody sandboxes this part as well without needing to use Cloudflare or something. [0]: https://developers.cloudflare.com/agents/api-reference/codem... [1]: https://github.com/vercel-labs/just-bash

https://github.com/vercel-labs/just-bash/blob/main/src/spec-... That's a lot of incompatibilities. LLMs like to use the shell because it's stable and virtually unchanged for decades. It doesn't need to worry much about versions or whether something is supported or not, it can just assume it is. Re-implementing bash is a herculean effort. I wish good luck.

If it's a coding agent, it will need to be able to write scripts and run them. I haven't tried just-bash, but it seems interesting for comparison: https://github.com/vercel-labs/just-bash

Sounds like just-bash: https://github.com/vercel-labs/just-bash