agent-skills-mirror

A Deno script that automatically discovers and mirrors AI agent skill repositories from GitHub.

What it does

agent-skills-mirror runs GitHub search queries to find repositories that contain AI agent skills, coding assistant instructions, Claude skills, Copilot instructions, MCP tool integrations, and related configuration files. For each discovered repository it performs a sparse checkout — pulling only the specific files relevant to skill/prompt/instruction consumption — and writes the results to a local mirrors/ directory.

Why it exists

The AI coding assistant ecosystem (Claude Code, GitHub Copilot, Cursor, Continue, Windsurf, MCP tools, etc.) has produced hundreds of high-signal skill and instruction repositories scattered across GitHub. This project aggregates them into one place so that:

• Tooling can consume skill files without cloning hundreds of repos.
• Humans can browse relevant instructions and prompts in one directory tree.
• Coverage can be measured and improved over time.

What kinds of repositories it discovers

The search queries target repositories that contain:

• Agent skills — SKILL.md, skills/**, skill/** files for Claude Code, GitHub Copilot agent mode, or custom coding agents.
• Copilot instructions — .github/instructions/**, .github/prompts/**, copilot-instructions.md.
• Claude/LLM config — CLAUDE.md, AGENTS.md, GEMINI.md, LLMs.txt.
• Cursor / Windsurf / Continue rules — .cursorrules, .cursor/rules/**, .windsurfrules, .continue/**.
• MCP integrations — .mcp/**, mcp/** directories.
• Prompt collections — prompts/**, prompt/**.

Non-GitHub sources (e.g. docs.stripe.com, open.feishu.cn, smithery.ai) are not indexed by this tool and should be consulted separately.

How to run

Prerequisites

• Deno ≥ 2.x
• Git (for sparse checkout)
• A GitHub personal access token (recommended to avoid rate-limits)

Basic run

deno run -A src/main.ts

With a GitHub token

# Using gh CLI
GH_TOKEN=$(gh auth token) deno run -A src/main.ts

# Or exporting directly
export GH_TOKEN=ghp_...
deno run -A src/main.ts

# GITHUB_TOKEN is also accepted
export GITHUB_TOKEN=ghp_...
deno run -A src/main.ts

Without a token, GitHub search is unauthenticated and heavily rate-limited (10 requests/min). With a token the limit is 30 requests/min for search.

Using the Deno task

deno task mirror

Running tests

deno task test

Controlling concurrency

MIRROR_CONCURRENCY=4 deno run -A src/main.ts

Default concurrency is 8 parallel repo checkouts.

What is mirrored and where

Mirrored files are written under mirrors/repos/<owner>@<name>/ — for example:

mirrors/repos/vercel-labs@agent-skills/
  skills/
    vercel-v0/SKILL.md
  .github/prompts/
    ...
  manifest.json

Each directory contains:

• The sparse-checked-out files matching the configured patterns.
• A manifest.json describing the repo, ref, patterns used, and file index.

The cache/ directory holds bare git clones and per-repo state files used to avoid redundant fetches between runs.

Sparse checkout patterns

Instead of cloning full repositories, the tool uses git sparse-checkout to pull only the files that match the configured include patterns. The global patterns are: