---
title: "Spec Mutator - Air Market"
description: "Your project needs a written spec, and it needs to stay one document rather than scattering. This is the only thing that edits SPEC.md at the repo root: it starts new specs, pulls one out of existing…"
canonical: "https://airmarket.ai/app/spec"
---

[Air Market](/) / [Developer Tools](/category/devtools) / Spec Mutator

Skill by [Julius Brussee](/@juliusbrussee)

# Spec Mutator

One place the project spec is written, amended and corrected

## What this does

Your project needs a written spec, and it needs to stay one document rather than scattering. This is the only thing that edits SPEC.md at the repo root: it starts new specs, pulls one out of existing code, adds invariants, amends sections, and records bugs. Reach for it any time the spec should change.

### Top 3 things it does for you

- Write a spec for a new idea
- Distill a spec out of code that already exists
- Amend one section without touching the rest

## Information

**Spec Mutator at a glance**

|  |  |
| --- | --- |
| Kind | Skill |
| Publisher | [Julius Brussee](/@juliusbrussee) |
| Category | [Developer Tools](/category/devtools) |
| Works with | Agent Skills - an open standard supported by 40+ agents |
| Size | 3 KB |
| Licence | MIT |
| Repository | [JuliusBrussee/cavekit](https://github.com/JuliusBrussee/cavekit/tree/c322f0bb6db82163041930467f3ce32754d42827/skills/spec) |
| GitHub stars | 1,142 (as of Nov 2026) |

## Security report

**Verified.** AIR scanned this exact version of Spec Mutator and flagged nothing. AIR's verdict: **safe**.

**What Spec Mutator's check was run against**

|  |  |
| --- | --- |
| Commit | c322f0bb6db82163041930467f3ce32754d42827 |
| Content hash | 7072dd41e3298b218f254c164ff2936f49e5ccff900f0bfba9055cc49b35011e |
| Files read | [Browse the files at this exact commit](https://github.com/JuliusBrussee/cavekit/blob/c322f0bb6db82163041930467f3ce32754d42827/skills/spec/SKILL.md) |

A scan is named by the exact content it read, not by a version number. A different version is a different artifact, and nothing here applies to a version AIR has not scanned.

[Read the full security report for Spec Mutator](/security/spec)

## About Spec Mutator

This creates, amends, and records bugs into SPEC.md at the repo root, and it is the sole mutator of that file - everything that changes the spec goes through here.

Ask it to write a spec, start a new one, distill a spec from code you already have, add invariants, amend a particular section, or record a bug. Phrasings like "write the spec for...", "new spec", "bug: ...", "amend §V.3", and "spec this idea" all reach it.

It reads and follows FORMAT.md for the caveman encoding rules and the pipe-table shape of the task and bug sections.

## What's inside

- SKILL.md - instructions

## Questions

### Is Spec Mutator safe to install?

AIR scanned this exact version of Spec Mutator and flagged nothing. AIR's verdict: safe. The verdict is named by the content that was read, at commit c322f0bb6db8, so it cannot drift onto a version nobody scanned. The full report is at https://airmarket.ai/security/spec.

### How do I install Spec Mutator?

Open https://airmarket.ai/app/spec on Air Market and use the install action: Air Market hands Claude a prompt naming this exact skill, and Claude sets it up. Source, pinned to the exact commit this listing describes: https://github.com/JuliusBrussee/cavekit/tree/c322f0bb6db82163041930467f3ce32754d42827/skills/spec. Install from that link, not the branch.

## Related on Air Market

- [More Developer Tools listings](/category/devtools)
- [Everything by Julius Brussee](/@juliusbrussee)

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Canonical URL: <https://airmarket.ai/app/spec>