airlock

airlock is a skill for Claude Code, Codex from ByJH/airlock. It costs 36 tokens per session (579 once invoked), scanned A, original, MIT.

A security gate for checking an agent extension before installation. It can inspect a skill, MCP server, or tool repository and return allow, quarantine, or block with evidence.

In plain words
What is it for?
Use it to audit an extension path or cloned repository, then use its exit code or JSON report in an installation script.
Why use it?
It helps identify dangerous behavior before untrusted code becomes part of an agent setup.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/byjh/airlock/skill
Any agent
npx skills add ByJH/airlock --skill skill
Clone the repo
git clone --depth 1 https://github.com/ByJH/airlock

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for airlock

README.md
[![agentmods](https://agentmods.dev/badge/skills/byjh/airlock/skill.svg)](https://agentmods.dev/skills/byjh/airlock/skill)
Your own site
<a href="https://agentmods.dev/skills/byjh/airlock/skill"><img src="https://agentmods.dev/badge/skills/byjh/airlock/skill.svg" alt="Measured on agentmods" height="20"></a>
Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 579 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00036 $0.00579
Opus 5 $0.00018 $0.00290
Sonnet 5 $0.00007 $0.00116
Haiku 4.5 $0.00004 $0.00058

Measured 3d ago against content hash cb4bc69322cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

airlock scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skill/SKILL.md · 58 lines

How it starts

The opening of the file, as written. The whole thing — 58 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Airlock

A gate for the things an agent installs. Use it before adding any skill, MCP server, or tool repo that came from a source you have not fully vetted. It works out what the artifact is, scans it for dangerous shapes, reads it adversarially with a model, detonates it once in a sealed sandbox, and returns one verdict.

When to run it

Run Airlock on an extension before the install step, not after. Good moments:

  • Someone shares a SKILL.md folder or a repo URL and asks you to install it.
  • You are about to add an MCP server you found in a public registry.
  • A dependency wants to run a lifecycle hook on install.

How to run it

Airlock is a Python command line tool. Install it once, then point it at a path or a cloned repo:

pip install -e ".[sandbox]"     # from the Airlock repo
airlock audit path/to/extension

The exit code is the gate, so a script or a hook can branch on it:

  • 0 allow. No known-bad shape, a clean or skipped judgment, no canary touch.
  • 1 quarantine. Something needs a human to look before it goes in.
  • 2 block. A critical finding, a canary touch, or a judged exfiltration.

Add --json for a machine-readable scorecard, --no-llm to run the deterministic core with no API key, and --no-sandbox to skip the container trial. The deterministic core always produces a verdict, even offline.

How to act on the verdict

  • On block, do not install the extension. Read the cited findings and tell the user which line drove the decision.
  • On quarantine, hold the install for a human review. Summarize what the scan and the judge flagged.
  • On allow, it is safe to proceed. A clean scan means no known-bad shape matched, not a proof of safety, so still prefer trusted sources.

What it looks at

The scorecard lists every finding with a file and line: credential-file reads, environment exfiltration, reverse shells, remote installers that pipe a downloaded script into a shell, package lifecycle hooks, and prompt-injection phrasing aimed at the agent reading the skill. The final gate is deterministic, so the same artifact always grades the same way and a model is never the last word on what gets in.

Read the full file on GitHub · 58 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 58 lines · 36 tokens per session scan A cb4bc69322cd

Subscribe to this mod's changes

airlock is a skill published in the GitHub repository ByJH/airlock (0 stars, last pushed 1mo ago), licensed MIT. It adds 36 tokens to every session and 579 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

brainstorming

You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.

obra/superpowers · 37 tokens

auto-perf-optimize

Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.

microsoft/vscode · 62 tokens

chat-perf

Run chat perf benchmarks and memory leak checks against the local dev build or any published VS Code version. Use when investigating chat rendering regressions, validating perf-sensitive changes to chat UI, or checking for memory leaks in the chat response pipeline.

microsoft/vscode · 51 tokens

chat-pet-sprite-creation

Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.

microsoft/vscode · 53 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens