---

name: code-reference-finder description: Find useful code references during development. Use when developer needs implementation examples, patterns, or wants to see how others solved similar problems. Triggers on "find examples of", "how do others implement", "show me similar projects", "find reference implementations", "what's the best practice for", or when external references would help.

Code Reference Finder

Help developers find useful code references. Show them options, let them choose.

Core Philosophy

• Inform, don't gatekeep — Note characteristics, don't hide results
• More options = more control — Show 5-10 results, not just 3
• Simple can be better — A clear 50-line example beats a 5000-line "proper" implementation for learning
• "Old" doesn't mean bad — Stable code that works is still useful
• User knows their context — They'll pick what fits

Workflow

Step 1: Understand the Request

Need Type	Signs	Approach
Quick snippet	"how do I...", specific function	Code search, show multiple files
Pattern/structure	"best way to...", architecture	Repo search, show directory layouts
Integration	"connect X with Y"	Search both terms, focus on config
Learning example	"example of...", student context	Include tutorials, demos, small repos
Production reference	"production-grade", scale concerns	Note which repos have tests/CI

If unclear, ask: "Looking for a quick snippet or a fuller example to study?"

Step 2: Search Effectively

Query formula: [what] + [technology] + [context]

Examples:

• "nextauth session callback typescript"
• "express middleware error handling"
• "react useEffect cleanup async"

Don't over-filter. Skip these unless user specifically wants production code:

• stars:>100 — cuts out useful small projects
• pushed:>2024-01-01 — old code can still be perfect
• -example -demo -tutorial — these are often exactly what learners need

Do use:

• language:typescript or language:python — match their stack
• path:src or path:lib — find implementation, not tests
• extension:tsx or extension:py — file type filtering

Step 3: Present Results with Context

Show 5-10 results with honest notes. Let user pick.

Template for each result:

**[Repo/File Name]** — [one-line description]
[stars] | Last updated: [date] | [size/complexity note]

[Why it might be useful for their specific question]

[Link to specific file/line]

Notes: [Any relevant context - old but clean, complex but complete, simple but limited, etc.]

Priority ordering (not filtering):

1. Best for learning — Clean, small, focused, well-commented
2. Best for copying — Modern stack match, working code, minimal dependencies
3. Best for understanding patterns — Good structure, clear separation
4. Production references — Has tests, CI, active maintenance
5. Historical/educational — Older but pedagogically valuable

Step 4: Add Useful Context (Not Judgments)

Note these characteristics, don't use them to exclude:

Characteristic	What to say
Last commit 2+ years ago	"Older codebase, but the pattern still applies"
No tests	"No test files visible" (neutral, not negative)
Small/simple	"Minimal implementation, good for understanding the core idea"
Large/complex	"Full-featured, might be more than you need"
Tutorial repo	"Explicitly educational, has explanations"
Few stars	"Lesser known but solves the problem"
Many stars	"Popular, well-documented"
Uses older syntax	"Uses [older pattern], you'd adapt to [newer equivalent]"

Step 5: Help Them Use What They Found

After showing options:

• Offer to explain any of the results in detail
• Offer to extract the specific relevant code
• Offer to adapt the pattern to their stack
• Answer follow-up questions

---

Search Patterns by Scenario

Authentication & Authorization

OAuth/Social Login:

grep.app: "NextAuth" "providers" path:auth language:typescript
github: topic:nextauth topic:prisma stars:>50 pushed:>2024-01-01

JWT Implementation:

grep.app: "jsonwebtoken" "verify" "sign" language:typescript -test
github: topic:jwt topic:express stars:>100

Session Management:

grep.app: "express-session" "cookie" "secure" path:middleware
grep.app: "iron-session" path:lib language:typescript

Database Patterns

Prisma Patterns:

grep.app: "prisma.client" "$transaction" language:typescript
grep.app: "PrismaClient" "middleware" path:lib

Drizzle ORM:

grep.app: "drizzle-orm" "pgTable" language:typescript
github: topic:drizzle topic:postgres stars:>30

MongoDB/Mongoose:

grep.app: "mongoose.Schema" "pre" "post" path:models
grep.app: "mongoose" "aggregate" "$lookup" language:typescript

API Design

REST with Express:

grep.app: "express.Router" "async" path:routes language:typescript
grep.app: "express" "middleware" "error" "next" path:src

tRPC:

grep.app: "createTRPCRouter" "procedure" language:typescript

GraphQL:

grep.app: "@Resolver" "Query" "Mutation" language:typescript
grep.app: "makeExecutableSchema" "typeDefs" "resolvers"

React Patterns

Server Components (App Router):

grep.app: "use server" "async" path:app language:typescript
grep.app: "cookies()" "headers()" path:app/api

State Management:

grep.app: "zustand" "create" "persist" language:typescript
grep.app: "useReducer" "dispatch" path:hooks

Custom Hooks:

grep.app: "export function use" path:hooks language:typescript -test
grep.app: "useState" "useEffect" "useCallback" path:hooks

Form Handling:

grep.app: "react-hook-form" "useForm" "register" language:tsx
grep.app: "zod" "zodResolver" "useForm" language:typescript

Testing

Unit Tests (Vitest/Jest):

grep.app: "describe" "it" "expect" "vi.mock" language:typescript path:test
grep.app: "beforeEach" "afterEach" "mock" path:__tests__

E2E (Playwright):

grep.app: "test" "page" "expect" "locator" path:e2e language:typescript

API Testing:

grep.app: "supertest" "request" "expect" path:test language:typescript

DevOps & Infrastructure

Docker:

grep.app: "FROM node" "WORKDIR" "COPY" extension:dockerfile
grep.app: "docker-compose" "services" "volumes" extension:yml path:docker

GitHub Actions:

grep.app: "uses:" "run:" path:.github/workflows extension:yml
grep.app: "actions/checkout" "pnpm" "test" path:.github

Error Handling & Logging

Error Boundaries:

grep.app: "ErrorBoundary" "componentDidCatch" language:tsx
grep.app: "error.tsx" "reset" path:app

Structured Logging:

grep.app: "pino" "logger" "child" language:typescript
grep.app: "winston" "createLogger" "transports"

File Handling

Upload/Download:

grep.app: "multer" "upload" "single" language:typescript
grep.app: "@uploadthing" path:src language:typescript

S3/Cloud Storage:

grep.app: "S3Client" "PutObjectCommand" language:typescript
grep.app: "@aws-sdk/client-s3" "getSignedUrl"

Real-time Features

WebSockets:

grep.app: "socket.io" "emit" "on" path:server language:typescript
grep.app: "ws" "WebSocket" "onmessage" language:typescript

Server-Sent Events:

grep.app: "ReadableStream" "TextEncoder" "event:" path:api
grep.app: "EventSource" path:hooks language:typescript

---

Pattern Extraction Guide

Directory Structure Reading

Next.js App Router:

app/
├── (auth)/              # Route groups
│   ├── login/page.tsx
│   └── register/page.tsx
├── api/                 # API routes
│   └── [resource]/route.ts
├── layout.tsx           # Root layout
└── page.tsx             # Home page

Key files: layout.tsx, page.tsx, route.ts

Express/Node Backend:

src/
├── routes/              # HTTP handlers
├── controllers/         # Business logic
├── middleware/          # Request processing
├── services/            # External integrations
├── models/              # Data models
└── utils/               # Helpers

Key files: routes/index.ts, middleware/*.ts

Where to Look First

User Needs	Look In
API endpoint logic	routes/, api/, handlers/
React component	components/, app/, pages/
Database queries	services/, repositories/, db/
Configuration	Root config files, config/
Custom hooks	hooks/, lib/hooks/
Utilities	utils/, lib/, helpers/
Types/interfaces	types/, *.d.ts, co-located with features

Extraction Templates

Snippet Extraction (< 50 lines):

## [What this does]

From: [repo/file:line-range]

[code block]

**Key points:**
- [Explain non-obvious line 1]
- [Explain non-obvious line 2]

**Adapt for your use:**
- Change [X] to [your equivalent]

Pattern Extraction (50-200 lines across files):

## [Pattern name]

Demonstrates: [what pattern solves]

### File structure needed:
[directory tree]

### Key file 1: [path]
[code]

### Key file 2: [path]
[code]

### How it connects:
[1-2 sentences on data flow]

### To adapt:
1. [First change]
2. [Second change]

---

Context Matching Guide

React Ecosystem

Era	Patterns	Key Indicators
React 16-17	Class components, HOCs, renderProps	Component, componentDidMount
React 18	Concurrent features, Suspense, transitions	startTransition, useDeferredValue
React 19	Server components default, use(), Actions	"use server", useActionState

Next.js Versions

Version	Router	Key Patterns
12 and below	Pages Router	pages/, getServerSideProps
13.0-13.3	App Router (beta)	app/ with limitations
13.4+	App Router (stable)	app/, server components
14+	Stable + improvements	app/, partial prerendering
15	Async request APIs	await cookies(), await headers()

Node.js Runtime

Runtime	Module System	Indicators
Node CJS	require/module.exports	"type": "commonjs" or absent
Node ESM	import/export	"type": "module"
Bun	ESM native, Bun APIs	Bun.serve, bun.lockb
Deno	ESM, URL imports	deps.ts, mod.ts

---

Quality Signals Reference

Understanding what repo characteristics mean — for context, not filtering.

Activity Signals

Signal	What it might mean	Don't assume
Last commit: this week	Actively developed	Code is stable or good
Last commit: months ago	Stable or slow development	It's abandoned or broken
Last commit: 2+ years	Project is "done" or truly abandoned	The code doesn't work

Reality: Some of the best learning code is in "finished" projects that haven't needed updates.

Star Count Context

Stars	Typical profile
0-10	Personal project, new project, niche solution
10-100	Useful to some people, might be exactly what you need
100-1000	Established solution, likely has docs
1000-10000	Popular tool/library, might be overkill for learning
10000+	Major project, probably a framework or tool itself

Hidden gems live in the 10-500 range. Not famous enough to be over-engineered, popular enough to be validated.

Describing Repos to Users

Instead of filtering, describe what you see:

• "Last updated 2021 — older but the auth pattern is still valid"
• "Smaller project (15 stars) but exactly solves the S3 upload case you asked about"
• "No test files — the code looks clean but you'd want to verify it works"
• "Full production setup (~80 files) — I can extract just the rate limiting middleware if you want simpler"

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Tool Integration

Works with:

• mcp.grep.app — Code search across millions of repos
• gitmcp.io/docs — Documentation for any GitHub repo
• GitHub MCP server — Repo search and metadata
• WebSearch — General web search for repos and examples

Without tools: Construct GitHub search URLs for user to explore.