github-codebase-search Skill

github-codebase-search

Semantic search for public GitHub repositories powered by MorphLLM — an RL-trained subagent that runs parallel grep+read calls against the GitHub API to answer natural language questions about code. No cloning required.

Requires MORPH_API_KEY environment variable.

When to Use

Understanding how a library or framework works internally (e.g., "how does Next.js resolve middleware?")
Investigating upstream bugs or behavior in open-source dependencies
Learning from reference implementations in well-known repos
Tracing code paths in a repo you haven't cloned locally
Exploring how an OSS project is structured or architected

When NOT to Use

Questions about the local codebase — use codebase-search
Private repositories (GitHub API access required)
Simple documentation lookup — use context7
Simple GitHub UI browsing (viewing READMEs, issues, PRs)

Decision Rule

Is the code on GitHub and not cloned locally? Use github-codebase-search. Is it in the local repo? Use codebase-search.

| Task | Tool | |------|------| | How does Next.js resolve API routes? | github-codebase-search | | How does our auth middleware work? | codebase-search | | How does Prisma handle migrations internally? | github-codebase-search | | Where is the database config in our repo? | codebase-search | | What does React's reconciler do with fibers? | github-codebase-search | | What does the React docs say about useEffect? | context7 |

Workflow

DO NOT read script source code. Run scripts directly and use --help for usage.

Run a Semantic Search

python3 scripts/github-codebase-search.py search "<natural language query>" --repo <owner/repo>

query — a natural language question about the code
--repo — GitHub repository in owner/repo format (e.g., vercel/next.js)
--url — alternative: full GitHub URL (e.g., https://github.com/vercel/next.js)
Must provide either --repo or --url

# Search by owner/repo
python3 scripts/github-codebase-search.py search "how does the router resolve middleware" --repo vercel/next.js

# Search by GitHub URL
python3 scripts/github-codebase-search.py search "how does the router resolve middleware" --url https://github.com/vercel/next.js

# Search a specific branch
python3 scripts/github-codebase-search.py search "how are migrations handled" --repo prisma/prisma --branch main

# Increase timeout for large repos
python3 scripts/github-codebase-search.py search "trace the build pipeline" --repo facebook/react --timeout 180

Run python3 scripts/github-codebase-search.py --help for full usage.

Example Output

Morph Fast Context subagent performed search on repository:

Relevant context found:
- src/routes/middleware.ts:*
- src/core/router.ts:50-120

Here is the content of files:

<file path="src/routes/middleware.ts">
1| import { NextRequest } from 'next/server';
2| export function middleware(request: NextRequest) {
...
</file>

<file path="src/core/router.ts">
50| function resolveMiddleware(chain: MiddlewareChain) {
...
120| }
</file>

The output lists relevant files and their content from the GitHub repo. If a file path is wrong, you may see Error: File not found — retry with a more specific query.

Rules

Write queries as natural language questions — "How does the router resolve middleware chains?" works far better than "router middleware", because the search agent plans its own strategy based on your question.
Be specific about what you want to know — "How does Prisma handle relation loading in findMany?" beats "Prisma relations".
Provide the owner/repo or URL — the tool needs to know which GitHub repo to search.
Default timeout is 120s — for large repos, increase with --timeout 180 or higher.

Agent Skills: github-codebase-search

Install this agent skill to your local

Skill Files