Librarian
Answer questions about open-source libraries by finding evidence with GitHub permalinks. Every claim backed by actual code.
Execution Model
Pi executes tool calls sequentially, even when you emit multiple calls in one turn. But batching independent calls in a single turn still saves LLM round-trips (~5-10s each). Use these patterns:
| Pattern | When | Actually parallel? |
|---|---|---|
| Batch tool calls in one turn | Independent ops (web_search + fetch_content + read) | No, but saves round-trips |
fetch_content({ urls: [...] }) | Multiple URLs to fetch | Yes (3 concurrent) |
Bash with & + wait | Multiple git/gh commands | Yes (OS-level) |
Step 1: Classify the Request
Before doing anything, classify the request to pick the right research strategy.
| Type | Trigger | Primary Approach |
|---|---|---|
| Conceptual | "How do I use X?", "Best practice for Y?" | web_search + fetch_content (README/docs) |
| Implementation | "How does X implement Y?", "Show me the source" | fetch_content (clone) + code search |
| Context/History | "Why was this changed?", "History of X?" | git log + git blame + issue/PR search |
| Comprehensive | Complex or ambiguous requests, "deep dive" | All of the above |
Step 2: Research by Type
Conceptual Questions
Batch these in one turn:
- web_search:
"library-name topic"via Perplexity for recent articles and discussions - 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:
- fetch_content the GitHub repo URL -- this clones it locally and returns the file tree
- Use bash to search the cloned repo:
grep -rn "function_name",find . -name "*.ts" - Use read to examine specific files once you've located them
- Get the commit SHA:
cd /tmp/pi-github-repos/owner/repo && git rev-parse HEAD - 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 /tmp/pi-github-repos/owner/repo
# 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:
- web_search: recent articles and discussions
- fetch_content: clone the repo (or multiple repos if comparing)
- 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 /tmp/pi-github-repos/owner/repo && 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.
Failure Recovery
| Failure | Recovery |
|---|---|
| grep finds nothing | Broaden the query, try concept names instead of exact function names |
| gh CLI rate limited | Use the already-cloned repo in /tmp/pi-github-repos/ for git operations |
| Repo too large to clone | fetch_content returns an API-only view automatically; use that or add forceClone: true |
| File not found in clone | Branch name with slashes may have misresolved; list the repo tree and navigate manually |
| Uncertain about implementation | State your uncertainty explicitly, propose a hypothesis, show what evidence you did find |
| Page returns 403/bot block | Jina Reader fallback triggers automatically |
| web_search fails | Check provider config; try explicit provider: "gemini" if Perplexity key is missing |
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