App Builder

App Builder — Application Building Orchestrator

> Analyzes requirements, determines tech stack, plans structure, and coordinates agents.

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🎯 Process Overview

User Request → Analyze → Select Stack → Plan → Scaffold → Coordinate → Verify

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📦 Recommended Default Stack

| Layer | Technology | Alternative | | ---------------- | ----------------------------- | ----------- | | Web Frontend | Next.js 14+ | Nuxt 3 | | Mobile | Expo (React Native) | Flutter | | Backend | NestJS | FastAPI | | Database | PostgreSQL + Prisma | Supabase | | Auth | NextAuth / Firebase Auth | Clerk | | Hosting | Vercel | Firebase | | Storage | Cloudinary / Firebase Storage | S3 |

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🔗 Agent Coordination

| Agent | Role | When to Invoke | | ------------------- | ---------------------------- | ---------------------------- | | planner | Task breakdown, dependencies | Starting any project | | architect | System design, patterns | Architecture decisions | | code-reviewer | Quality, patterns | After implementation | | security-reviewer | Security posture | Auth, payment features | | tdd-guide | Test specifications | Before/during implementation |

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📋 Project Type Detection

| Keywords | Project Type | Default Stack | | --------------------------------- | ----------------- | ----------------------- | | "web app", "website", "dashboard" | Web Application | Next.js + Prisma | | "mobile app", "iOS", "Android" | Mobile App | Expo + NestJS API | | "API", "backend", "server" | API Service | NestJS + Prisma | | "landing page", "marketing" | Static Site | Next.js (static export) | | "CLI", "command line" | CLI Tool | Node.js + Commander | | "extension", "plugin" | Browser Extension | Chrome MV3 |

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🏗️ Scaffolding Process

Step 1: Clarify Requirements

Before scaffolding, confirm:

1. Project type (web/mobile/API/etc.)
2. Core features (3-5 max for MVP)
3. Auth requirements (none/social/email)
4. Database needs (none/simple/complex)

Step 2: Create Plan

## Project Plan: [Name]

### Core Features

1. [Feature 1]
2. [Feature 2]
3. [Feature 3]

### Tech Stack

- Frontend: [choice]
- Backend: [choice]
- Database: [choice]

### File Structure

[directory tree]

### Implementation Order

1. Setup & configuration
2. Database schema
3. API endpoints
4. Frontend pages
5. Authentication
6. Testing

Step 3: Scaffold

# Example: Next.js project
npx create-next-app@latest ./project-name \
  --typescript \
  --eslint \
  --tailwind \
  --app \
  --src-dir

Step 4: Coordinate Agents

1. Invoke planner → Task breakdown
2. Invoke architect → Design decisions
3. Execute tasks sequentially
4. Invoke tdd-guide → Add tests
5. Invoke code-reviewer → Final review

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📁 Standard Directory Structures

Next.js Full-Stack

src/
├── app/              # Pages & routes
│   ├── api/          # API routes
│   └── (auth)/       # Auth pages
├── components/       # React components
├── lib/              # Utilities
├── server/           # Server-side logic
│   ├── db/           # Prisma client
│   └── services/     # Business logic
└── types/            # TypeScript types

NestJS API

src/
├── modules/          # Feature modules
│   ├── auth/
│   ├── users/
│   └── [feature]/
├── common/           # Shared utilities
│   ├── decorators/
│   ├── guards/
│   └── interceptors/
└── config/           # Configuration

Expo Mobile

src/
├── app/              # Expo Router screens
├── components/       # UI components
├── hooks/            # Custom hooks
├── services/         # API clients
├── stores/           # Zustand stores
└── utils/            # Helpers

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✅ Post-Scaffold Checklist

• [ ] Dependencies installed
• [ ] Environment variables documented
• [ ] README updated
• [ ] Git initialized
• [ ] Basic tests passing
• [ ] Development server runs

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Usage Example

User: "Create a task management app with user auth"

App Builder Process:
1. Project type: Web Application
2. Tech stack: Next.js + Prisma + NextAuth
3. Create plan:
   ├─ Database schema (users, tasks, lists)
   ├─ API routes (CRUD for tasks)
   ├─ Pages (dashboard, tasks, settings)
   └─ Components (TaskCard, TaskList, etc.)
4. Scaffold project
5. Coordinate agents for implementation
6. Run verification loop

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: besync-labs
• Source: besync-labs/antigravity-ai-kit
• License: MIT
• Homepage: https://besync-labs.github.io/antigravity-ai-kit/

Install and usage instructions live in the source repository linked above.