Building Full-Stack Apps with Antigravity Agent Mode: From Prompt to Production (2025)
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Nick
December 27, 2025
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Building Full-Stack Apps with Antigravity Agent Mode: From Prompt to Production
Agent Mode: Your Autonomous AI Development Partner
Agent Mode is Google Antigravity's most powerful feature—and the one that changes everything about how we build software. Unlike traditional AI assistants that respond to individual prompts, Agent Mode operates autonomously. Give it a goal, and it plans, codes, debugs, and iterates until the job is done.
In this comprehensive tutorial, we'll build a complete full-stack SaaS application from scratch using Agent Mode. By the end, you'll have a deployed production app with user authentication, database integration, subscription payments, and a professional UI.
What we're building: BookShelf—a personal reading tracker where users can log books, track reading progress, set goals, and share their reading history.
Notice the production-ready features: loading states, error handling, proper TypeScript types, and clean component structure.
Part 3: Database Schema and Data Layer
Now let's build the core functionality:
"Design and implement the database schema and data layer for BookShelf:
Database Tables:
profiles - user profile info (linked to auth.users)
books - book entries with title, author, cover_url, isbn
reading_entries - tracks reading sessions
reading_goals - annual/monthly reading goals
shelves - custom shelves for organizing books
Requirements:
Create Supabase migration files
Implement Row Level Security policies
Create TypeScript types for all tables
Build a data access layer with typed functions for CRUD operations"
Generated Migration File
Agent Mode creates a proper SQL migration with tables, RLS policies, indexes, and triggers.
Generated Data Access Layer
// src/lib/data/books.ts
import { createClient } from '@/lib/supabase/server'
import { Book, NewBook, UpdateBook } from '@/types'
export async function getBooks(shelf?: Book['shelf']) {
const supabase = await createClient()
let query = supabase
.from('books')
.select('*')
.order('created_at', { ascending: false })
if (shelf) {
query = query.eq('shelf', shelf)
}
const { data, error } = await query
if (error) {
throw new Error(`Failed to fetch books: ${error.message}`)
}
return data as Book[]
}
Part 4: Building the User Interface
Create the main application UI with:
Dashboard with reading stats
Book grid with shelf filtering
Add/edit book forms
Reading progress tracking
Goals management
Part 5: Adding Stripe Payments
Implement subscription payments:
Free tier (10 books)
Premium ($5/month) - unlimited books
Annual ($48/year) - 20% discount
Agent Mode creates checkout sessions, webhook handlers, and feature gating.
Part 6: Deployment to Production
Prepare for deployment with:
Environment variables checklist
Vercel configuration
Error monitoring (Sentry)
Health check endpoints
SEO optimization
Agent Mode Best Practices
1. Be Specific About Requirements
Weak prompt: "Add user profiles"
Strong prompt: "Add user profiles with username, avatar upload to Supabase Storage, bio (max 500 chars), and social links. Include profile edit page and public profile view."
2. Break Complex Features into Phases
Phase 1: Data model and database schema
Phase 2: Backend API and data layer
Phase 3: UI components
Phase 4: Integration and polish
3. Review Each Step
Don't blindly accept all changes. Agent Mode shows you what it's doing—take time to review.
4. Use .antigravity Rules
# .antigravity rules
## Code Style
- Use TypeScript strict mode
- Prefer async/await over .then()
- Use named exports over default exports
- Add JSDoc comments for public functions
## Architecture
- Use Server Components by default
- Client components only when necessary
- Keep components small and focused
5. Handle Agent Mistakes
When the Agent makes an error, give specific feedback instead of starting over.
Complete Project Stats
Metric
Value
Total Files Generated
~60 files
Lines of Code
~4,000 lines
Time Spent
2-3 hours
Traditional Dev Time
20-30 hours
Time Saved
~90%
FAQs
How does Agent Mode handle existing code?
Agent Mode can work with existing projects. It analyzes your current code structure and integrates new features accordingly.
What if Agent Mode generates buggy code?
Describe the bug in follow-up prompts. Agent Mode can diagnose and fix issues.
Can I use Agent Mode for any language/framework?
Agent Mode works best with popular frameworks (Next.js, React, Python, etc.).
Is the generated code production-ready?
For most cases, yes. The code includes proper error handling, types, and security practices.
Conclusion
Agent Mode transforms software development from typing code to directing an AI developer. In this tutorial, we built a complete full-stack SaaS application in 2-3 hours instead of 20-30.
This isn't about replacing developers; it's about amplifying what we can accomplish. The ideas, architecture decisions, and quality standards are still yours. Agent Mode just handles the implementation at superhuman speed.