speckit-extension

speckit-extension is a skill for Claude Code from github/spec-kit-copilot. It costs 100 tokens per session (777 once invoked), scanned A, original, MIT.

An extension manager for Spec Kit, a toolkit for planning software through written specifications. Extensions add reusable commands or hooks to a Spec Kit project.

In plain words
What is it for?
Use it to search extension catalogs, install extensions from a catalog or local directory, update them, and control their priority.
Why use it?
It provides one place to find, install, update, enable, disable, and remove project extensions.

Skill for Claude Code ✓ vendor

Written for Claude Code: argument-hint in frontmatter.

Good fit Use it to search extension catalogs, install extensions from a catalog or local directory, update them, and control their priority.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/github/spec-kit-copilot/speckit-extension
About the project

github/spec-kit-copilot is a repository of GitHub Copilot integrations for Spec Kit, a toolkit for developing software through a structured specification-first workflow. It provides Copilot-specific commands, skills, canvases, and related workflow components for users of the Copilot CLI, Copilot App, and VS Code.

github/spec-kit-copilot · 18 stars · on GitHub

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.

Any agent
npx skills add github/spec-kit-copilot --skill speckit-extension
Clone the repo
git clone --depth 1 https://github.com/github/spec-kit-copilot

Made for: Claude Code.

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 speckit-extension

README.md
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Your own site
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agentmods 80×15 button for speckit-extension

Your own site · 80×15
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Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 777 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00100 $0.00777
Opus 5.5 $0.00040 $0.00311
Sonnet 5.5 $0.00020 $0.00155
Haiku 4.5 $0.00010 $0.00078

Measured 1mo ago against content hash 528c9e9d8193, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

speckit-extension 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 1mo 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.

skills/speckit-extension/SKILL.md · 69 lines

How it starts

The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec Kit — extensions

Manage spec-kit extensions with the Specify CLI specify extension command group. Extensions add reusable commands/hooks to a spec-kit project.

Prerequisite: needs the specify CLI. If specify --version fails, install it with the speckit-cli-setup skill first.

When to use

  • Find, install, update, or remove a spec-kit extension.
  • Temporarily enable/disable an extension or adjust its resolution priority.
  • Add or manage extension catalog sources.

How to invoke

# Discover
specify extension list
specify extension list --json                 # machine-readable installed inventory (CLI >= 1.0.7)
specify extension search <query>
specify extension info <name>

# Install
specify extension add <name>
specify extension add <name> --force            # overwrite if already installed
specify extension add <path> --dev              # install from a local directory
specify extension add <name> --from <url>       # install from a custom URL
specify extension add <name> --priority <n>     # lower number = higher precedence

# Lifecycle
specify extension update [<name>]               # update one or all extensions
specify extension enable <name>
specify extension disable <name>
specify extension set-priority <name> <n>
specify extension remove <name>

# Catalogs (sources extensions are resolved from)
specify extension catalog list
specify extension catalog add <https-url> --name <name> [--install-allowed] [--priority <n>] [--description <text>]
specify extension catalog remove <name>

Extension catalog URLs must use HTTPS. New catalogs are not install-allowed by default — pass --install-allowed to permit installing extensions from them.

Notes

  • Resolution priority: lower number = higher precedence (default 10).
  • specify extension list --json requires Specify CLI >= 1.0.7 and returns installed extensions only, even when combined with --available or --all. Each item includes id, name, description, version, nullable author, priority, enabled, normalized source, and provides counts for commands, templates, scripts, and hooks.
  • Prefer specify extension search first so you install the correct extension ID.
  • --dev is for local development of an extension; point it at the extension's source directory.
  • When the project was initialized in skills mode (see the speckit-init skill), an installed extension's commands land as .github/skills/speckit-<cmd>/SKILL.md. To make Copilot pick up the new skills in the current session, run /skills reload (no restart needed). They are also loaded automatically on the next session start.

Read the full file on GitHub · 69 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. 1mo ago Changed · +6 lines · +17 tokens per session 528c9e9d8193
  2. 1mo ago First seen · 63 lines · 83 tokens per session scan A aba1330e6128

Subscribe to this mod's changes

speckit-extension is a skill published in the GitHub repository github/spec-kit-copilot (18 stars, last pushed today), licensed MIT. It adds 100 tokens to every session and 777 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-08-30.

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