🚀 Enterprise Next.js Boilerplate (Antigravity Edition)

FOR AI AGENTS & DEVELOPERS: This documentation is structured to provide deep context, architectural decisions, and operational details to ensure seamless handover to any AI coding assistant (like Antigravity) or human developer.

---

🧠 Project Context & Architecture (Read Me First)

This is an opinionated, production-ready frontend boilerplate built with Next.js 16 App Router. It is designed to work seamlessly with the companion typescript-boilerplate-be NestJS backend.

🏗️ Core Philosophy

• Type Safety First: Strict TypeScript configuration. DTOs and typed API responses connect frontend to backend.
• App Router Native: Built entirely on Next.js App Router with Server Components and React Server Actions support.
• i18n Native: Localization is baked into routing, API calls, and UI components via next-intl.
• Theme-First Design: Chakra UI v3 with custom theme system for consistent, accessible UI.
• Auth by Default: NextAuth.js integration with JWT token management and automatic session handling.

📐 Architectural Decision Records (ADR)

To understand WHY things are the way they are:

1. Locale-Based Routing:

   • Mechanism: All routes are prefixed with locale (e.g., /tr/dashboard, /en/login).
   • Implementation: next-intl plugin with [locale] dynamic segment in app/ directory.
   • Config: localePrefix: 'always' ensures consistent URL structure.

2. API Client with Auto-Auth & Locale:

   • Location: src/lib/api/create-api-client.ts
   • Feature: Automatically injects JWT Authorization header from NextAuth session.
   • Feature: Automatically sets Accept-Language header based on current locale (cookie or URL path).
   • Auto-Logout: 401 responses trigger automatic signOut and redirect.

3. Backend Proxy (CORS Solution):

   • Problem: Local development CORS issues when frontend (port 3001) calls backend (port 3000).
   • Solution: Next.js rewrites in next.config.ts proxies /api/backend/* → http://localhost:3000/api/*.
   • Usage: API clients use /api/backend/... paths in development.

4. Provider Composition:

   • Location: src/components/ui/provider.tsx
   • Stack: SessionProvider (NextAuth) → ChakraProvider (UI) → ColorModeProvider (Dark/Light) → Toaster (Notifications)
   • Why: Single import in layout provides all necessary contexts.

---

🚀 Quick Start for AI & Humans

1. Prerequisites

• Node.js: v20.19+ (LTS)
• Package Manager: npm (Lockfile: package-lock.json)
• Backend: Companion NestJS backend running on port 3000 (see typescript-boilerplate-be)

2. Environment Setup

cp .env.example .env.local
# Edit .env.local with your configuration

Required Environment Variables:

Variable	Description	Example
NEXTAUTH_URL	NextAuth callback URL	http://localhost:3001
NEXTAUTH_SECRET	Authentication secret (generate with openssl rand -base64 32)	abc123...
NEXT_PUBLIC_API_URL	Backend API base URL	http://localhost:3001/api
NEXT_PUBLIC_AUTH_REQUIRED	Require login for all pages	true or false

3. Installation & Running

# Install dependencies
npm ci

# Development Mode (HTTPS enabled, port 3001)
npm run dev

# Production Build
npm run build
npm run start

Note: Dev server runs on port 3001 with experimental HTTPS for secure cookie handling.

---

🌍 Internationalization (i18n) Guide

Deep integration with next-intl provides locale-aware routing and translations.

Configuration

• Supported Locales: ['en', 'tr']
• Default Locale: tr
• Locale Detection: Cookie (NEXT_LOCALE) → URL path → Default

File Structure

messages/
├── en.json       # English translations
└── tr.json       # Turkish translations

src/i18n/
├── routing.ts    # Locale routing configuration
├── navigation.ts # Typed navigation helpers (Link, useRouter)
└── request.ts    # Server-side i18n setup

Usage in Components

// Client Component
"use client";
import { useTranslations } from "next-intl";

export function MyComponent() {
  const t = useTranslations("common");
  return <h1>{t("welcome")}</h1>;
}

// Navigation with Locale
import { Link } from "@/i18n/navigation";

<Link href="/dashboard">Dashboard</Link>; // Auto-prefixes with current locale

Adding a New Locale

1. Add locale code to src/i18n/routing.ts:

   export const locales = ["en", "tr", "de"]; // Add 'de'
   

2. Create messages/de.json with translations.
3. Update getLocale() in create-api-client.ts if needed.

---

🔐 Authentication System

Built on NextAuth.js with JWT strategy for seamless backend integration.

How It Works

1. Login: User submits credentials → /api/auth/[...nextauth] → Backend validates → JWT returned.
2. Session: JWT stored in encrypted cookie, accessible via useSession() hook.
3. API Calls: createApiClient() automatically adds Authorization: Bearer {token} header.
4. Auto-Refresh: Token refreshed before expiry (managed by NextAuth).

Protected Routes

// Use middleware.ts or check session in layout
import { getServerSession } from "next-auth";

export default async function ProtectedLayout({ children }) {
  const session = await getServerSession();
  if (!session) redirect("/login");
  return <>{children}</>;
}

Auth Mode Toggle

Set NEXT_PUBLIC_AUTH_REQUIRED=true for mandatory authentication across all pages.

---

🎨 UI System (Chakra UI v3)

Theme Configuration

• Location: src/theme/theme.ts
• Font: Bricolage Grotesque (Google Fonts, variable font)
• Color Mode: Light/Dark with system preference detection

Component Organization

src/components/
├── ui/                 # Chakra UI wrapper components
│   ├── provider.tsx    # Root provider (Session + Chakra + Theme)
│   ├── color-mode.tsx  # Dark/Light mode toggle
│   ├── feedback/       # Toaster, alerts, etc.
│   └── ...
├── layout/             # Page layout components (Header, Sidebar, Footer)
├── auth/               # Authentication forms and guards
└── site/               # Site-specific feature components

Toast Notifications

import { toaster } from "@/components/ui/feedback/toaster";

// Success toast
toaster.success({
  title: "Saved!",
  description: "Changes saved successfully.",
});

// Error toast
toaster.error({ title: "Error", description: "Something went wrong." });

---

📡 API Integration

Creating API Clients

// src/lib/api/auth/login/queries.ts
import { createApiClient } from "../create-api-client";

const api = createApiClient("/api/backend/auth");

export const loginUser = async (data: LoginDto) => {
  const response = await api.post("/login", data);
  return response.data;
};

React Query Integration

import { useQuery, useMutation } from "@tanstack/react-query";

// Query hook
export const useUsers = () =>
  useQuery({
    queryKey: ["users"],
    queryFn: () => apiClient.get("/users"),
  });

// Mutation hook
export const useCreateUser = () =>
  useMutation({
    mutationFn: (data: CreateUserDto) => apiClient.post("/users", data),
  });

---

📂 System Map (Directory Structure)

src/
├── app/                    # Next.js App Router
│   ├── [locale]/           # Locale-prefixed routes
│   │   ├── (auth)/         # Auth pages (login, register)
│   │   ├── (site)/         # Main site pages
│   │   ├── (error)/        # Error pages
│   │   ├── layout.tsx      # Root layout with providers
│   │   └── page.tsx        # Home page
│   └── api/                # Next.js API routes
│       └── auth/           # NextAuth endpoints
├── components/             # React components
│   ├── ui/                 # Chakra UI wrappers & base components
│   ├── layout/             # Layout components (Header, Sidebar)
│   ├── auth/               # Auth-related components
│   └── site/               # Feature-specific components
├── config/                 # App configuration
├── hooks/                  # Custom React hooks
├── i18n/                   # Internationalization setup
├── lib/                    # Utilities & services
│   ├── api/                # API clients (organized by module)
│   │   ├── auth/           # Auth API (login, register)
│   │   ├── admin/          # Admin API (roles, users)
│   │   └── create-api-client.ts  # Axios factory with interceptors
│   ├── services/           # Business logic services
│   └── utils/              # Helper functions
├── theme/                  # Chakra UI theme configuration
├── types/                  # TypeScript type definitions
└── proxy.ts                # API proxy utilities

messages/                   # Translation JSON files
public/                     # Static assets

---

🧪 Testing & Development

Available Scripts

npm run dev      # Start dev server (HTTPS, port 3001)
npm run build    # Production build
npm run start    # Start production server
npm run lint     # Run ESLint

Development Tools

• React Compiler: Enabled for automatic optimization.
• Top Loader: Visual loading indicator for route transitions.
• ESLint + Prettier: Consistent code formatting.

---

🛠️ Troubleshooting (Known Issues)

1. HTTPS Certificate Warnings in Development

• Context: Dev server uses --experimental-https for secure cookies.
• Fix: Accept the self-signed certificate warning in your browser.

2. Backend Connection Refused

• Fix: Ensure NestJS backend is running on port 3000.
• Check: Run curl http://localhost:3000/api/health to verify.

3. Session Not Persisting

• Fix: Ensure NEXTAUTH_SECRET is set and consistent between restarts.
• Fix: Check that cookies are not blocked by browser settings.

4. Locale Not Detected

• Context: Default falls back to tr if cookie/URL detection fails.
• Fix: Clear NEXT_LOCALE cookie and refresh.

---

🔗 Related Projects

• Backend: typescript-boilerplate-be - NestJS backend with Prisma, JWT auth, and i18n.

---

📃 License

This project is proprietary and confidential.