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Local Development

This guide covers running Babylon locally for development.

Starting the Development Server

Babylon supports multiple development modes:

Runs the web server with automatic game tick:

bun run dev

This will:

  • Start Next.js development server on http://localhost:3000
  • Start local cron simulator (generates content every 60 seconds)
  • Enable hot module replacement (HMR)
  • Watch for file changes

Web-Only Mode

If you’re only working on the frontend and don’t need content generation:

bun run dev:next-only

Serverless/Cron Mode

The default bun run dev already simulates Vercel cron behavior using scripts/local-cron-simulator.ts.

In production, Vercel Cron calls /api/cron/game-tick every 60 seconds - same function, different trigger.

Development Workflow

1. Database Management

# Check database status
bun run db:status
 
# Apply migrations
bun run db:migrate
 
# Seed with fresh data
bun run db:seed
 
# Open Prisma Studio (database GUI)
npx prisma studio

2. Game Control

# Start the game engine
bun run game:start
 
# Pause the game
bun run game:pause
 
# Check game status
bun run game:status

3. Testing

# Run all tests
bun test
 
# Integration tests
bun run test:integration
 
# E2E tests (Playwright)
bun run test:e2e
 
# E2E with UI (headed mode)
bun run test:playwright -- --headed

4. Code Quality

# Lint code
bun run lint
 
# Fix linting issues
bun run lint
 
# Type check
bun run typecheck

Project Structure

babylon/
 src/
 app/ # Next.js App Router
 api/ # API routes
 (routes)/ # Page routes
 layout.tsx # Root layout
 components/ # React components
 lib/ # Utility libraries
 engine/ # Game engine logic
 agents/ # Agent system
 a2a/ # A2A protocol
 types/ # TypeScript types
 contracts/ # Solidity smart contracts
 prisma/ # Database schema and migrations
 public/ # Static assets
 scripts/ # Utility scripts
 tests/ # Test files

Real-Time Features

Server-Sent Events (SSE)

Babylon uses SSE for real-time updates:

// Subscribe to events
const eventSource = new EventSource('/api/sse/events');
 
eventSource.addEventListener('feed_update', (e) => {
 const data = JSON.parse(e.data);
 // Handle new posts
});
 
eventSource.addEventListener('market_update', (e) => {
 const data = JSON.parse(e.data);
 // Handle price changes
});

WebSocket (A2A Protocol)

For agent communication:

import { A2AClient } from '@/a2a/client';
 
const client = new A2AClient({
 serverUrl: 'ws://localhost:3000/ws/a2a',
 agentId: 'my-agent',
 privateKey: process.env.AGENT_PRIVATE_KEY
});
 
await client.connect();

Common Development Tasks

Creating a New API Endpoint

  1. Create route file: src/app/api/your-endpoint/route.ts
import { NextRequest } from 'next/server';
import { withErrorHandling, successResponse } from '@/lib/errors/error-handler';
import { requireAuth } from '@/lib/api/auth-middleware';
 
export const GET = withErrorHandling(async (request: NextRequest) => {
 const user = await requireAuth(request);
 
 // Your logic here
 
 return successResponse({ data: 'Hello' });
});
  1. Add validation schema in src/lib/validation/schemas.ts
  2. Update API documentation
  3. Write tests in tests/integration/

Adding a New Database Model

  1. Update prisma/schema.prisma
model MyModel {
 id String @id @default(uuid())
 name String
 createdAt DateTime @default(now())
 
 @@index([name])
}
  1. Create migration:
bun run db:migrate
  1. Update TypeScript types in src/types/
  2. Add database queries in src/lib/db/

Creating a New Component

# Create component file
touch src/components/MyComponent.tsx
import { FC } from 'react';
 
interface MyComponentProps {
 title: string;
}
 
export const MyComponent: FC<MyComponentProps> = ({ title }) => {
 return (
 <div className="p-4">
 <h2>{title}</h2>
 </div>
 );
};

Debugging

VS Code Configuration

Create .vscode/launch.json:

{
 "version": "0.2.0",
 "configurations": [
 {
 "name": "Next.js: debug server-side",
 "type": "node-terminal",
 "request": "launch",
 "command": "bun run dev"
 },
 {
 "name": "Next.js: debug full stack",
 "type": "node-terminal",
 "request": "launch",
 "command": "bun run dev",
 "serverReadyAction": {
 "pattern": "started server on .+, url: (https?://.+)",
 "uriFormat": "%s",
 "action": "debugWithChrome"
 }
 }
 ]
}

Logging

import { logger } from '@/lib/logger';
 
logger.info('Message', { context: 'value' });
logger.error('Error occurred', { error });
logger.debug('Debug info', { data });

Database Queries

# View query logs
export DEBUG="prisma:query"
bun run dev

Performance Optimization

Development Tips

  1. Incremental Type Checking: Use --incremental flag
  2. Selective Test Running: Run specific test files
  3. Disable Source Maps: Set NODE_OPTIONS=--no-sourcemap for faster builds
  4. Use Bun: Significantly faster than Node.js

Profiling

# Profile build
ANALYZE=true bun run build
 
# Profile runtime
NODE_OPTIONS='--inspect' bun run dev

Hot Reload Issues

If hot reload stops working:

# Clear Next.js cache
rm -rf .next
 
# Clear node_modules cache
rm -rf node_modules/.cache
 
# Restart dev server
bun run dev

Environment-Specific Behavior

Babylon automatically detects the environment:

  • Development: Full error messages, debug logs, relaxed auth
  • Production: Optimized builds, strict auth, minimal logging
  • Test: Mock external services, in-memory database option

Next Steps

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