Building Real-Time Full-Stack Apps with Antigravity and Supabase: A Practical Guide

Why Antigravity and Supabase Make a Great Pair

Building a full-stack application usually means juggling a lot of moving parts: database design, authentication, real-time communication, and file storage. Each of these can take days to implement from scratch.

Supabase has quickly become one of the most popular open-source alternatives to Firebase. It offers a managed PostgreSQL database, built-in authentication, real-time subscriptions, and edge functions — everything you need for a modern app, powered by standard SQL instead of a proprietary NoSQL system.

When you combine Supabase with Antigravity IDE's agent capabilities, you get an incredibly productive workflow. The AI agent can help you design schemas, generate type-safe client code, implement real-time subscriptions, and debug RLS policies — all from within your editor. In this guide, we'll walk through building a real-time task management app using this powerful stack.

Understanding Supabase's Core Architecture

Supabase is built on top of several open-source technologies, each serving a distinct purpose:

PostgreSQL Database: A fully managed PostgreSQL instance with Row Level Security (RLS) for granular access control at the database level
Auth: Authentication supporting email/password, OAuth providers (Google, GitHub, etc.), and magic links
Realtime: A WebSocket engine that broadcasts PostgreSQL changes to connected clients instantly
Storage: S3-compatible file storage for images, documents, and other assets
Edge Functions: Deno-based serverless functions for handling webhooks and background tasks

The biggest advantage over Firebase is that you get standard SQL. If you already know SQL, you can model your data intuitively. Supabase is also open-source, which means less vendor lock-in and the option to self-host when you outgrow the managed service.

Setting Up Your Antigravity Project

Start by creating a new Next.js project in Antigravity and installing the Supabase client libraries. You can ask the agent to scaffold the entire setup with a single prompt.

# Ask the Antigravity agent:
# "Create a Next.js 15 + TypeScript + Supabase project"
 
# The agent will run commands like:
npx create-next-app@latest task-app --typescript --tailwind --app
cd task-app
 
# Install Supabase client libraries
npm install @supabase/supabase-js @supabase/ssr

Next, create a Supabase project through the dashboard and configure your environment variables.

# .env.local
NEXT_PUBLIC_SUPABASE_URL=https://your-project.supabase.co
NEXT_PUBLIC_SUPABASE_ANON_KEY=YOUR_SUPABASE_ANON_KEY
SUPABASE_SERVICE_ROLE_KEY=YOUR_SERVICE_ROLE_KEY

The key best practice is to create separate Supabase client instances for server and client components.

// src/lib/supabase/client.ts — Browser client
import { createBrowserClient } from "@supabase/ssr";
 
export function createClient() {
  return createBrowserClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!
  );
}

// src/lib/supabase/server.ts — Server client
import { createServerClient } from "@supabase/ssr";
import { cookies } from "next/headers";
 
export async function createClient() {
  const cookieStore = await cookies();
  return createServerClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!,
    {
      cookies: {
        getAll() {
          return cookieStore.getAll();
        },
        setAll(cookiesToSet) {
          cookiesToSet.forEach(({ name, value, options }) =>
            cookieStore.set(name, value, options)
          );
        },
      },
    }
  );
}

Just tell the Antigravity agent "Set up Supabase SSR clients" and it will generate this configuration automatically. For a broader look at authentication patterns, our Auth.js v5 authentication guide covers similar concepts, though Supabase Auth is simpler when you're already using the Supabase ecosystem.

Database Schema Design with Row Level Security

Use the Supabase SQL Editor or have the Antigravity agent generate your schema. Here's a practical task management schema.

-- Create tasks table
create table public.tasks (
  id uuid default gen_random_uuid() primary key,
  user_id uuid references auth.users(id) on delete cascade not null,
  title text not null,
  description text,
  status text default 'todo' check (status in ('todo', 'in_progress', 'done')),
  priority integer default 0 check (priority between 0 and 3),
  due_date timestamptz,
  created_at timestamptz default now(),
  updated_at timestamptz default now()
);
 
-- Enable Row Level Security
alter table public.tasks enable row level security;
 
-- Policies: users can only access their own tasks
create policy "Users can view own tasks"
  on public.tasks for select
  using (auth.uid() = user_id);
 
create policy "Users can insert own tasks"
  on public.tasks for insert
  with check (auth.uid() = user_id);
 
create policy "Users can update own tasks"
  on public.tasks for update
  using (auth.uid() = user_id);
 
create policy "Users can delete own tasks"
  on public.tasks for delete
  using (auth.uid() = user_id);
 
-- Auto-update the updated_at timestamp
create or replace function update_updated_at()
returns trigger as $$
begin
  new.updated_at = now();
  return new;
end;
$$ language plpgsql;
 
create trigger tasks_updated_at
  before update on public.tasks
  for each row execute function update_updated_at();

Row Level Security is one of Supabase's most powerful features. It lets you enforce authorization rules at the database level, eliminating the need for server-side middleware to filter data. Ask the Antigravity agent to "add RLS policies for this table" and it will analyze the schema and suggest appropriate policies.

Auto-Generating TypeScript Types

For TypeScript projects, generating types from your Supabase schema dramatically improves the agent's code quality and your development experience.

# Install the Supabase CLI
npm install -D supabase
 
# Generate TypeScript types
npx supabase gen types typescript --project-id your-project-id > src/types/database.ts

These generated types make every query type-safe.

// Convenient type aliases from the generated file
export type Task = Database["public"]["Tables"]["tasks"]["Row"];
export type InsertTask = Database["public"]["Tables"]["tasks"]["Insert"];
export type UpdateTask = Database["public"]["Tables"]["tasks"]["Update"];

Implementing Real-Time Sync

Supabase Realtime broadcasts PostgreSQL changes over WebSocket connections. This is perfect for collaborative features or syncing data across multiple devices.

// src/hooks/useRealtimeTasks.ts
"use client";
 
import { useEffect, useState } from "react";
import { createClient } from "@/lib/supabase/client";
import type { Task } from "@/types/database";
 
export function useRealtimeTasks(userId: string) {
  const [tasks, setTasks] = useState<Task[]>([]);
  const supabase = createClient();
 
  useEffect(() => {
    // Fetch initial data
    const fetchTasks = async () => {
      const { data, error } = await supabase
        .from("tasks")
        .select("*")
        .eq("user_id", userId)
        .order("created_at", { ascending: false });
 
      if (!error && data) {
        setTasks(data);
      }
    };
 
    fetchTasks();
 
    // Subscribe to real-time changes
    const channel = supabase
      .channel("tasks-realtime")
      .on(
        "postgres_changes",
        {
          event: "*", // Listen to INSERT, UPDATE, and DELETE
          schema: "public",
          table: "tasks",
          filter: `user_id=eq.${userId}`,
        },
        (payload) => {
          switch (payload.eventType) {
            case "INSERT":
              setTasks((prev) => [payload.new as Task, ...prev]);
              break;
            case "UPDATE":
              setTasks((prev) =>
                prev.map((t) =>
                  t.id === (payload.new as Task).id
                    ? (payload.new as Task)
                    : t
                )
              );
              break;
            case "DELETE":
              setTasks((prev) =>
                prev.filter((t) => t.id !== payload.old.id)
              );
              break;
          }
        }
      )
      .subscribe();
 
    return () => {
      supabase.removeChannel(channel);
    };
  }, [userId, supabase]);
 
  return tasks;
}

Tell the Antigravity agent "Create a real-time sync hook for the tasks table" and it will generate a hook like this. Notice the filter parameter that restricts events to the current user's tasks — this optimizes performance by reducing unnecessary WebSocket traffic.

Remember to enable Realtime for your table in the Supabase dashboard (Database → Tables → tasks → Realtime toggle).

Building the Authentication Flow

Supabase Auth makes it straightforward to implement both email authentication and OAuth sign-in.

// src/app/auth/login/page.tsx
"use client";
 
import { useState } from "react";
import { createClient } from "@/lib/supabase/client";
import { useRouter } from "next/navigation";
 
export default function LoginPage() {
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const supabase = createClient();
  const router = useRouter();
 
  const handleLogin = async (e: React.FormEvent) => {
    e.preventDefault();
    setLoading(true);
    setError(null);
 
    const { error } = await supabase.auth.signInWithPassword({
      email,
      password,
    });
 
    if (error) {
      setError(error.message);
    } else {
      router.push("/dashboard");
      router.refresh();
    }
    setLoading(false);
  };
 
  const handleGoogleLogin = async () => {
    await supabase.auth.signInWithOAuth({
      provider: "google",
      options: {
        redirectTo: `${window.location.origin}/auth/callback`,
      },
    });
  };
 
  return (
    <form onSubmit={handleLogin}>
      <input
        type="email"
        value={email}
        onChange={(e) => setEmail(e.target.value)}
        placeholder="Email address"
        required
      />
      <input
        type="password"
        value={password}
        onChange={(e) => setPassword(e.target.value)}
        placeholder="Password"
        required
      />
      {error && <p className="text-red-500">{error}</p>}
      <button type="submit" disabled={loading}>
        {loading ? "Signing in..." : "Sign in"}
      </button>
      <button type="button" onClick={handleGoogleLogin}>
        Sign in with Google
      </button>
    </form>
  );
}

Don't forget to handle the OAuth callback route as well.

// src/app/auth/callback/route.ts
import { createClient } from "@/lib/supabase/server";
import { NextResponse } from "next/server";
 
export async function GET(request: Request) {
  const { searchParams, origin } = new URL(request.url);
  const code = searchParams.get("code");
 
  if (code) {
    const supabase = await createClient();
    const { error } = await supabase.auth.exchangeCodeForSession(code);
    if (!error) {
      return NextResponse.redirect(`${origin}/dashboard`);
    }
  }
 
  return NextResponse.redirect(`${origin}/auth/error`);
}

Common Errors and How to Fix Them

Here are the most frequent issues you'll encounter when developing with Supabase in Antigravity, along with their solutions.

Data returns empty despite existing rows

This is almost always caused by missing RLS policies. When RLS is enabled but no policies are defined, Supabase returns zero rows for safety. Tell the agent "I can't fetch data from the tasks table" and it will check your RLS configuration.

-- Debug: temporarily disable RLS to verify data exists
-- WARNING: never do this in production
alter table public.tasks disable row level security;

Real-time events not arriving

Verify that Realtime is enabled for your table in the Supabase dashboard. Also note that RLS policies apply to Realtime channels too — your subscription will only receive events for rows the user has permission to read.

Environment variables not accessible

Variables without the NEXT_PUBLIC_ prefix are only available server-side. The SUPABASE_SERVICE_ROLE_KEY intentionally lacks this prefix since it should never be exposed to the browser.

Looking back

The combination of Antigravity and Supabase represents a modern approach to full-stack development that dramatically reduces time-to-production. With PostgreSQL's reliability, built-in authentication, real-time sync, and Antigravity's AI-powered coding assistance, you can build features in hours that used to take days.

The key takeaways from this guide are: separate your Supabase clients for server and browser contexts, leverage Row Level Security for secure data access at the database level, and use real-time subscriptions to keep your UI in sync without manual polling.

For production-level security patterns and validation strategies, check out Building Secure API Backends with Antigravity Agents for a deeper dive. If you're planning to add a payment system, the Antigravity SaaS Stripe Full-Stack Guide is an excellent next step.