command-guard SKILL.md skillA
command-guard from jkheadley/instar is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add jkheadley/instar/command-guard@v1.0Pins v1.0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- jkheadley/instar
- Path
skills/command-guard/SKILL.md- Versions recorded
- 1
- Latest version
- v1.0, committed Feb 21, 2026
- Size
- 8,217 bytes
- Repository stars
- 84
- License
- MIT
Set up a PreToolUse hook in .claude/settings.json that blocks dangerous commands — rm -rf, force push, database drops, and others — before they execute. Teaches the pattern of safety hooks for any Claude Code project. Trigger words: safety, guard, block dangerous, protect, prevent destructive, safe mode, dangerous commands, risky operations.
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
# command-guard — Block Dangerous Commands Before They Execute Claude Code runs shell commands, edits files, and manages infrastructure with real consequences. Without guardrails, a misunderstood instruction or a hallucinated flag can delete data, corrupt history, or expose credentials. This skill installs a PreToolUse hook that blocks the most dangerous operations before they run. No external tools required — this uses Claude Code's built-in hook system. --- ## What Gets Blocked The guard intercepts `Bash` tool calls and checks the command against a blocklist before execution. By default it blocks: **Irreversible deletions** - `rm -rf` on non-temporary paths - `git clean -f` (untracked file deletion) **Git history destruction** - `git push --force` / `git push -f` (without explicit user confirmation) - `git reset --hard` on shared branches - `git rebase` on pushed branches **Database operations** - `DROP TABLE`, `DROP DATABASE`, `TRUNCATE` in SQL - `db:reset`, `db:drop` npm/prisma scripts **Credential exposure** - Commands that `cat`, `echo`, or `curl` files containing `SECRET`, `KEY`, `TOKEN`, `PASSWORD` to stdout --- ## Installation …
Read the whole file at its exact version.
How to install
mdr add jkheadley/instar/command-guard@sha256:a2cc8ab468afaa29The line at the top of this page pins the label v1.0, 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_pz7gtwqzcs6ewz2f)
5 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Feb 21, 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 (8217 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
jkheadley/instar · 84 stars · license MIT · pushed 2026-10-21 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_pz7gtwqzcs6ewz2f GET https://markdownregistry.com/api/v1/resolve?ref=jkheadley/instar/command-guard GET https://markdownregistry.com/api/v1/blob/a2cc8ab468afaa2990bd8540cc05c49e8dafef525dd34987db355c618ee8de16
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.