monday-code-dev

name	monday-code-dev
description	Start development servers and local environment for monday code apps. Use when user says "start dev server", "run frontend", "run backend", "npm run dev", "start local environment", "set up local dev", or "run the app locally".
argument-hint	[frontend|backend|all]
user-invocable	true
allowed-tools	["Bash","Read","Write","Glob","Grep"]

monday-dev

Start development servers and set up the local environment for monday code apps.

When to Use

• User wants to start the development server
• User wants to run frontend dev server (Vite)
• User wants to run backend dev server (Express with watch mode)
• User wants to run both frontend and backend
• User wants to set up local MongoDB for Document DB

Instructions

Step 1: Detect Project Structure

Check which directories exist:

ls -d frontend/ backend/ 2>/dev/null

• frontend/ exists → Frontend app
• backend/ exists → Backend app
• Both exist → Fullstack app

Step 2: Pre-Flight Checks

Check dependencies are installed:

# Frontend
[ -d "frontend/node_modules" ] || (cd frontend && npm install)

# Backend
[ -d "backend/node_modules" ] || (cd backend && npm install)

Check environment files:

For backend, verify .env exists. If not, check for .env.example:

[ -f "backend/.env" ] || echo "WARNING: No .env file found in backend/"

Required backend env vars:

• MONDAY_CLIENT_SECRET - For JWT verification (set in Developer Center > OAuth)
• MNDY_MONGODB_CONNECTION_STRING - For Document DB (local: mongodb://localhost:27017/appname)

Step 3: Start Local MongoDB (if backend uses Document DB)

Check if the backend uses MongoDB:

grep -r "MNDY_MONGODB_CONNECTION_STRING\|mongodb\|MongoClient" backend/src/ 2>/dev/null

If it does, ensure a local MongoDB is running:

# Check if MongoDB is already running
docker ps --filter name=monday-app-mongo --format "{{.Names}}" 2>/dev/null

# If not running, start one:
docker run -d --name monday-app-mongo -p 27017:27017 mongo:7

Set in backend/.env:

MNDY_MONGODB_CONNECTION_STRING=mongodb://localhost:27017/monday-app

Step 4: Start Dev Servers

Frontend only:

cd frontend && npm run dev

Starts Vite on port 3000 with HMR. Access at http://localhost:3000.

Backend only:

cd backend && npm run dev

Starts Express with tsx watch mode on port 8080 (or PORT env var). Auto-reloads on file changes.

Fullstack (both servers):

Run each in a separate background process:

# Start backend first (frontend may depend on it)
cd backend && npm run dev &

# Then frontend
cd frontend && npm run dev

Or suggest the user to open two terminal tabs.

Step 5: Local Dev Detection

The frontend MondayContext should auto-detect local development. It works by checking:

const isLocalDev =
  !window.location.ancestorOrigins?.length &&  // Not inside monday.com iframe
  import.meta.env.DEV;                         // Vite dev mode

When in local dev mode:

• Monday SDK calls return mock data (test-user-1, test-account-1)
• API calls use VITE_DEV_TOKEN for authentication
• No real monday.com connection needed

Step 6: Testing with monday.com

To test the app inside monday.com, you will need to create the app and the desired app feature in the monday.com Developer Center. You can use the local dev server for the frontend and a tunnel for the backend.

If building a backend for automations/integrations on monday.com production with real monday.com webhooks/integrations, the user needs a tunnel:

# Using ngrok (or similar)
mapps tunnel:create -p 8080

Then set the tunnel URL in monday.com Developer Center go to: Your app > Features > your app feature > Deployment > External hosting

And put in the fielsd the tunnel URL (e.g. https://548f50475f79.apps-tunnel.monday.app)

For frontend testing inside monday.com:

• Use the local dev server URL (http://localhost:3000) as the feature's Deployment URL in Developer Center

Troubleshooting

Problem	Solution
Port 3000/8080 already in use	Kill the existing process: lsof -ti:3000 | xargs kill or change the port
node_modules missing	Run npm install in the relevant directory
Docker not running (MongoDB)	Start Docker Desktop, then re-run the docker run command
.env file missing	Copy from .env.example if available, or create manually with required vars
MONDAY_CLIENT_SECRET not set	Get it from Developer Center > Your App > OAuth and add to backend/.env
Frontend shows blank page	Check browser console; ensure Vite dev server is running on port 3000

Example

User says: "Start the dev server for my fullstack app"

Actions:

1. Detect frontend/ and backend/ directories exist (fullstack)
2. Run npm install in both if node_modules missing
3. Check if backend uses MongoDB; start local container if needed
4. Start backend with cd backend && npm run dev
5. Start frontend with cd frontend && npm run dev

Result: Backend running on http://localhost:8080, frontend on http://localhost:3000 with HMR