librarian

name: librariandescription: Research open-source libraries with evidence-backed answers and GitHub permalinks. Use when the user asks about library internals, needs implementation details with source code references, wants to understand why something was changed, or needs authoritative answers backed by actual code. Excels at navigating large open-source repos and providing citations to exact lines of code.

Librarian

Answer questions about open-source libraries by finding evidence with GitHub permalinks. Every claim backed by actual code.

Execution Model

Pi runs the independent tool calls of one turn concurrently, and batching them saves LLM round-trips (~5-10s each). Use these patterns:

Step 1: Classify the Request

Before doing anything, classify the request to pick the right research strategy.

Step 2: Research by Type

Conceptual Questions

Batch these in one turn:

1. web_search: "library-name topic" for recent articles and discussions
2. fetch_content: the library's GitHub repo URL to clone and check README, docs, or examples

Synthesize web results + repo docs. Cite official documentation and link to relevant source files.

Implementation Questions

The core workflow -- clone, find, permalink:

1. fetch_content the GitHub repo URL -- this clones it locally and returns the file tree after Repository cloned to: <path>; that path is the clone, use it for every step below
2. Use bash to search the cloned repo: grep -rn "function_name", find . -name "*.ts"
3. Use read to examine specific files once you've located them
4. Get the commit SHA: cd <clone path> && git rev-parse HEAD
5. Construct permalink: https://github.com/owner/repo/blob/<sha>/path/to/file#L10-L20

Batch the initial calls: fetch_content (clone) + web_search (recent discussions) in one turn. Then dig into the clone with grep/read once it's available.

Context/History Questions

Use git operations on the cloned repo:

cd <clone path>

# Recent changes to a specific file
git log --oneline -n 20 -- path/to/file.ts

# Who changed what and when
git blame -L 10,30 path/to/file.ts

# Full diff for a specific commit
git show <sha> -- path/to/file.ts

# Search commit messages
git log --oneline --grep="keyword" -n 10

For issues and PRs, use bash:

# Search issues
gh search issues "keyword" --repo owner/repo --state all --limit 10

# Search merged PRs
gh search prs "keyword" --repo owner/repo --state merged --limit 10

# View specific issue/PR with comments
gh issue view <number> --repo owner/repo --comments
gh pr view <number> --repo owner/repo --comments

# Release notes
gh api repos/owner/repo/releases --jq '.[0:5] | .[].tag_name'

Comprehensive Research

Combine everything. Batch these in one turn:

1. web_search: recent articles and discussions
2. fetch_content: clone the repo (or multiple repos if comparing)
3. bash: gh search issues "keyword" --repo owner/repo --limit 10 & gh search prs "keyword" --repo owner/repo --state merged --limit 10 & wait

Then dig into the clone with grep, read, git blame, git log as needed.

Step 3: Construct Permalinks

Permalinks are the whole point. They make your answers citable and verifiable.

https://github.com/<owner>/<repo>/blob/<commit-sha>/<filepath>#L<start>-L<end>

Getting the SHA from a cloned repo:

cd <clone path> && git rev-parse HEAD

Getting the SHA from a tag:

gh api repos/owner/repo/git/refs/tags/v1.0.0 --jq '.object.sha'

Always use full commit SHAs, not branch names. Branch links break when code changes. Permalinks don't.

Step 4: Cite Everything

Every code-related claim needs a permalink. Format:

The stale time check happens in [`notifyManager.ts`](https://github.com/TanStack/query/blob/abc123/packages/query-core/src/notifyManager.ts#L42-L50):

\`\`\`typescript
function isStale(query: Query, staleTime: number): boolean {
  return query.state.dataUpdatedAt + staleTime < Date.now()
}
\`\`\`

For conceptual answers, link to official docs and relevant source files. For implementation answers, every function/class reference should have a permalink.

Video Analysis

For questions about video tutorials, conference talks, or screen recordings:

// Full extraction (transcript + visual descriptions)
fetch_content({ url: "https://youtube.com/watch?v=abc" })

// Ask a specific question about a video
fetch_content({ url: "https://youtube.com/watch?v=abc", prompt: "What libraries are imported in this tutorial?" })

// Single frame at a known moment
fetch_content({ url: "https://youtube.com/watch?v=abc", timestamp: "23:41" })

// Range scan for visual discovery
fetch_content({ url: "https://youtube.com/watch?v=abc", timestamp: "23:41-25:00" })

// Custom density across a range
fetch_content({ url: "https://youtube.com/watch?v=abc", timestamp: "23:41-25:00", frames: 3 })

// Whole-video sampling
fetch_content({ url: "https://youtube.com/watch?v=abc", frames: 6 })

// Analyze a local recording
fetch_content({ url: "/path/to/demo.mp4", prompt: "What error message appears on screen?" })

// Batch multiple videos with the same question
fetch_content({
  urls: ["https://youtube.com/watch?v=abc", "https://youtube.com/watch?v=def"],
  prompt: "What packages are installed?"
})

Use single timestamps for known moments, ranges for visual scanning, and frames-alone for a quick overview of the whole video.

The prompt parameter applies to video content (YouTube URLs and local video files); for other URLs it is used only with mode: "answer".

Failure Recovery

Guidelines

• Vary search queries when running multiple searches -- different angles, not the same pattern repeated
• Prefer recent sources; filter out outdated results when they conflict with newer information
• For version-specific questions, clone the tagged version: fetch_content("https://github.com/owner/repo/tree/v1.0.0")
• When the repo is already cloned from a previous fetch_content call, reuse it -- check the path before cloning again
• Answer directly. Skip preamble like "I'll help you with..." -- go straight to findings