netlify-functions

Netlify Functions — Serverless API Patterns Plugin

Scaffold and implement production-ready Netlify Functions with built-in security, error handling, and TypeScript patterns.

The Problem

New function created → no CORS → frontend gets blocked
                     → no try/catch → unhandled errors crash silently
                     → no auth → endpoint exposed to anyone
                     → different patterns per function → codebase inconsistency

Each developer reinvents the same boilerplate. When a project has 20+ functions, conventions drift.

The Solution

┌──────────────┐     ┌──────────────┐     ┌──────────────┐     ┌──────────────┐
│ Build registry│ --> │ 27 functions │ --> │ Create new   │ --> │ Hook warns:  │
│ fn-registry.sh│     │ analyzed     │     │ function     │     │ "27/27 use   │
└──────────────┘     └──────────────┘     └──────────────┘     │ createHandler│
         │                   │                                  │ — use it too"│
         └── registry.json ──┘── patterns: supabase auth ──────┘──────────────┘
             (type, auth,         handler path,
              CORS per fn)        common imports)

Key Features

Feature	Description
4 Function Types	API endpoints, webhooks, scheduled (cron), background tasks
Pattern Detection	Scans existing functions for createHandler, auth provider, common imports
Auto-Check Hook	Warns on missing CORS, error handling, suggests project patterns
Function Registry	.netlify-fn/registry.json — inventory with type, auth, patterns
Auth Provider Detection	Auto-detects Supabase, Firebase, Auth0, Clerk usage
Convention Enforcement	"27/27 functions use createHandler() — use it here too"
History Tracking	Function count and pattern snapshots across registry builds

Installation

# From marketplace
/plugin install netlify-functions@JHyeok5

# Or clone directly
git clone https://github.com/JHyeok5/claude-plugin-netlify-functions.git
claude --plugin-dir ./claude-plugin-netlify-functions

Note: Restart Claude Code after installation to activate hooks.

Usage

/netlify-functions:netlify-functions

Or describe your need — auto-triggers on Netlify tasks:

• "Create a new API endpoint"
• "Add a Stripe webhook handler"
• "Set up a daily cron function"
• "Add authentication to my Netlify function"

Build Registry (recommended on first use)

bash scripts/fn-registry.sh /path/to/project

This scans netlify/functions/ and creates .netlify-fn/registry.json with detected patterns.

How It Works

[Registry Build — fn-registry.sh]
  1. Scan netlify/functions/*.ts|js (skip lib/ subdirectory)
  2. Classify each function: api | webhook | scheduled | background
  3. Detect per-function: hasAuth, hasCors, hasErrorHandling, usesCreateHandler
  4. Detect project patterns: auth provider, handler path, common imports
  5. Save to .netlify-fn/registry.json + append history

[Hooks (automatic on file Write)]
  New function created → check for:
    1. CORS handling (OPTIONS/Access-Control)
    2. Error handling (try/catch)
    3. TypeScript type annotations
    4. Handler wrapper usage (if project uses createHandler)
    5. Auth provider match (if project uses supabase/firebase/etc.)
  → Skip CORS/error warnings if handler wrapper detected
  → Show pattern stats: "27/27 functions use createHandler()"

Patterns Included

Pattern	Use Case	Features
Universal Handler	Any endpoint	CORS, method check, error handling, body parsing
Webhook Handler	Stripe, GitHub, Apple	Signature verification, event routing
Scheduled Function	Cron jobs	Daily cleanup, cache refresh, reports
Auth-Protected	User data endpoints	Token verification, user context
Error Codes	All functions	Consistent error response format

Supported Auth Providers

Provider	Verification Method
Supabase	supabase.auth.getUser(token)
Firebase	admin.auth().verifyIdToken(token)
Auth0	JWKS + jsonwebtoken
Clerk	clerkClient.verifyToken(token)
Custom JWT	jsonwebtoken.verify(token, secret)

Auto-Check Hook

When installed, the plugin monitors new Netlify Function files:

| Check | Without Registry | With Registry |