opensrc — Agent skill by vercel-labs

Downloads the actual source code of a library your project depends on, at the exact version your project uses, so you can read how it really works instead of guessing.

WHEN TO USE

SCOPE

USE FOR

Understand internal behavior of a dependency that its type definitions don't reveal.
Debug unexpected library behavior by reading its actual implementation.
Learn coding patterns from a well-known package's real source, like Zod or React.
Verify exactly how a function handles an edge case before relying on it.
Fetch the exact source version matching a project's lockfile automatically.

NOT FOR

Simple API usage questions that documentation or types already answer.

This is a saved copy of the skill's SKILL.md instructions. It may differ from the upstream file or the version you install.

In this document (5)

Source Code Fetching with opensrc

Fetches dependency source code so agents can read implementations, not just types. Clones repositories at the correct version tag and caches them globally at ~/.opensrc/.

Core Pattern

rg "parse" $(opensrc path zod)
cat $(opensrc path zod)/src/types.ts
find $(opensrc path zod) -name "*.test.ts"

opensrc path <pkg> prints the absolute path to cached source. If not cached, it fetches automatically. Progress goes to stderr, path to stdout, so $(opensrc path ...) works in subshells.

Fetching Source Code

opensrc path zod
opensrc path pypi:requests
opensrc path crates:serde
opensrc path facebook/react

# Multiple packages at once
opensrc path zod react next
opensrc path pypi:requests pypi:flask
opensrc path crates:serde crates:tokio

# Specific versions
opensrc path zod@3.22.0
opensrc path pypi:flask@3.0.0
opensrc path owner/repo@v1.0.0
opensrc path owner/repo#main

Version Resolution

For npm packages, opensrc auto-detects the installed version from lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock). Use --cwd to resolve from a different project:

opensrc path zod --cwd /path/to/project

For PyPI and crates.io, explicit versions or latest are used. For repos, use @ref or #ref to pin a branch, tag, or commit.

Managing the Cache

Source is cached globally at ~/.opensrc/ (override with OPENSRC_HOME).

opensrc list                     # show all cached sources
opensrc list --json              # JSON output

opensrc remove zod               # remove a package
opensrc remove facebook/react    # remove a repo

opensrc clean                    # remove everything
opensrc clean --npm              # only npm packages
opensrc clean --pypi             # only PyPI packages
opensrc clean --crates           # only crates.io packages
opensrc clean --packages         # all packages, keep repos
opensrc clean --repos            # all repos, keep packages

When to Fetch Source

Fetch source when you need to:

Understand internal behavior that types don't reveal
Debug unexpected library behavior
Learn patterns from well-known implementations
Verify how a function handles edge cases

Don't fetch source for simple API usage questions that docs or types can answer.

Local tool required

1 FOR YOU

01
Install the opensrc CLI
Install the opensrc command-line tool locally (it clones and caches dependency source code at ~/.opensrc/); the skill runs opensrc path <package> to fetch source before reading it.

Listed as free: Connected services may require an account or charge fees.
Installation: One command — usually under 2 minutes.

Not standalone. This skill ships with vercel-labs/opensrc and only works together with that tool — install the tool first, then add this skill.

Run this outside your AI tool, using Node.js 22.20.0 or newer. Skills CLI 1.7.2 skips skill selection; prompts cancel installation without an interactive terminal. If choosing Project when asked about installation scope, open your project's folder before running this.

Install checklist

Check selected tools if a picker appears; Claude Code may be unchecked under Additional agents. ↑/↓ moves, Space toggles selections, Enter confirms.
Without a tool picker, check Installing to: for your intended tool. Stop if it names a different tool.
If asked, choose Symlink (Recommended) for shared files or Copy to all agents for separate copies; review the summary before confirming installation.
Install the find-skills skill? defaults to Yes, adding another skill for all projects. Choose No if you don't want that extra installation.

Skills CLI 1.7.2 sends install data to skills.sh by default, including the source, skill names, target tools and file details; GitHub sources are reported only when GitHub confirms the repository is public, while other remote sources can also be reported. Confirmed-public GitHub sources also trigger a security-audit request. Before installing, set the environment variable DO_NOT_TRACK=1 or DISABLE_TELEMETRY=1 to disable both.

npx skills add vercel-labs/opensrc --skill "opensrc" --full-depth

After installing for Claude Code, open it in the installation project if you chose Project; Global makes the skill available across projects on this computer. Once Claude Code loads the skill, its description helps Claude decide when to use it.

If installation created a top-level skills folder that did not exist when your Claude Code session started, run /reload-skills in that session. Run it again after later changes in that folder.

What's inside

Files included with this skill.

View on GitHub

The repository is licensed under Apache-2.0 — use, modification, and redistribution are allowed under that license’s terms.

View the repository’s license file on GitHub →