forkable-shell SKILL.md skillA
forkable-shell from broomva/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add broomva/skills/forkable-shell@git:20260927.1060cb5Pins git:20260927.1060cb5 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- broomva/skills
- Path
skills/compute/forkable-shell/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260927.1060cb5, committed Sep 27, 2026
- Size
- 7,994 bytes
- Repository stars
- 5
- License
- MIT
Gives an agent session a disposable, sandboxed bash shell whose entire filesystem is a single JSON file — so the workspace can be snapshotted, forked, branched and resumed at ~0.24ms per fork instead of seconds per container. Backed by just-bash (in-process, no VM, no container, no host access). Use when you want to run agent-generated shell commands without giving them a real machine, checkpoint an agent workspace, fork one workspace into N parallel branches to try competing approaches…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# forkable-shell
A **world** is one JSON file holding an entire agent workspace: the virtual filesystem
plus shell state. Because a world is a single value, **forking is a file copy**.
Shell continuity is best-effort and self-reporting: state is replayed between calls,
and when a command exits before it can be captured, `exec()` says so rather than
pretending nothing changed.
```text
world.json ──fork──> A.json (branch A works here)
└─fork──> B.json (branch B works here)
trunk is never opened, so it cannot be mutated
```
## Setup
```bash
cd skills/compute/forkable-shell && npm install # just-bash + MCP SDK
```
Requires **Node ≥ 20.18.1**. Run it under `node`, not `bun` — see Constraints.
## CLI (`scripts/vbash.mjs`)
```bash
node scripts/vbash.mjs init <world> [--seed <hostfile>:<guestpath>]...
node scripts/vbash.mjs fork <src> <dst>
node scripts/vbash.mjs exec <world> <command...>
node scripts/vbash.mjs cat <world> <guestpath>
node scripts/vbash.mjs info <world>
node scripts/vbash.mjs mcp-config <world> [--log <path>]
node scripts/vbash.mjs drive <world> <prompt> [--log <p>] [--model m] [--max-turns n]
```
…Read the whole file at its exact version.
How to install
mdr add broomva/skills/forkable-shell@sha256:389f430a0a3528bbThe line at the top of this page pins the label git:20260927.1060cb5, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_g7vry5xckw345ivb)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Sep 27, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (7994 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
broomva/skills · 5 stars · license MIT · pushed 2026-11-07 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_g7vry5xckw345ivb GET https://markdownregistry.com/api/v1/resolve?ref=broomva/skills/forkable-shell GET https://markdownregistry.com/api/v1/blob/389f430a0a3528bbcf281acafbaa15b33cec6b67dec3a1fec0507d294efdd266
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.