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Spec

Spec is an agent skill (a SKILL.md file) from JuliusBrussee/cavekit. Create, amend, or backprop bugs into SPEC.md at repo root. It works with Claude Code and Codex and has 1,148 GitHub stars across a repository of 2 listed skills. Install it by copying the skill folder into your agent's skills directory.

github.com/JuliusBrussee/cavekit/skills/spec (opens in a new tab)

  • Multi-skill repo
  • Plugin marketplace
  • Testing & QA
  • Actively maintained
View on GitHub (opens in a new tab)

Add this skill

Claude

This repository is a Claude Code plugin marketplace. In Claude Code:

/plugin marketplace add JuliusBrussee/cavekit
/plugin install ck@cavekit-marketplace

In the Claude apps, zip the spec folder and upload it under Customize > Skills > + > Upload a skill (code execution must be on).

ChatGPT / Codex

Codex reads skills from .agents/skills/ in a repo or ~/.agents/skills/ for every project:

git clone --depth 1 https://github.com/JuliusBrussee/cavekit.git
cp -r cavekit/skills/spec .agents/skills/spec   # repo; ~/.agents/skills for all projects

Standalone skills also load in the ChatGPT desktop app.

Cursor

Cursor loads skills from .cursor/skills/ (or ~/.cursor/skills/) and also reads .claude/skills/:

git clone --depth 1 https://github.com/JuliusBrussee/cavekit.git
cp -r cavekit/skills/spec .cursor/skills/spec   # project; ~/.cursor/skills for all projects

Source (checked Oct 7, 2026): code.claude.com/docs/en/skills (opens in a new tab), code.claude.com/docs/en/plugin-marketplaces (opens in a new tab), support.claude.com/en/articles/12512180-using-skills-in-claude (opens in a new tab), learn.chatgpt.com/docs/build-skills (opens in a new tab), cursor.com/docs/context/skills (opens in a new tab)

What this skill does

Create, amend, or backprop bugs into SPEC.md at repo root. Sole mutator of the project spec. Triggers when the user asks to write a spec, start a new spec, distill a spec from existing code, add invariants, amend sections (§G, §C, §I, §V, §T, §B), or record a bug via backprop. Common phrasings: "write the spec for...", "new spec", "bug: ...", "amend §V.3", "distill spec from code", "spec this idea". Reads and follows FORMAT.md for the caveman encoding rules and pipe-table shape of §T and §B.

When it triggers

  • Triggers when the user asks to write a spec, start a new spec, distill a spec from existing code, add invariants, amend sections (§G, §C, §I, §V, §T, §B), or record a bug via backprop.
  • "write the spec for..."
  • "new spec"
  • "bug: ..."
  • "amend §V.3"
  • "distill spec from code"
  • "spec this idea"

More skills in JuliusBrussee/cavekit

2 skills are listed from this repository.

Similar skills

More testing & qa skills

All Testing & QA

FAQ

Spec FAQ

Still curious? Email info@appsgit.com.

What is the Spec skill?

Spec is an agent skill (a SKILL.md file) from JuliusBrussee/cavekit. Create, amend, or backprop bugs into SPEC.md at repo root. It works with Claude Code and Codex and has 1,148 GitHub stars across a repository of 2 listed skills. Install it by copying the skill folder into your agent's skills directory. Its SKILL.md lives at github.com/JuliusBrussee/cavekit/skills/spec.

How do I install the Spec skill?

In Claude Code, run /plugin marketplace add JuliusBrussee/cavekit and then /plugin install ck@cavekit-marketplace. For Codex or Cursor, copy the spec folder into .agents/skills/ or .cursor/skills/.

Is the Spec skill free?

Yes. The repository is open source under the MIT license.

Is Spec maintained?

The repository's most recent commit was on Aug 14, 2026. Its latest release is v3.1.0. appsgit only lists skills from repositories with a commit in the last six months.