Supabase Expert

Overview

Comprehensive guidance for working with Supabase including database operations, authentication, storage, edge functions, and Next.js integration. Enforces security patterns, performance optimizations, and modern best practices.

Critical Rules

API Keys (New System)

Supabase now offers two key types with improved security:

Key Type	Prefix	Safety	Use Case
Publishable	sb_publishable_...	Safe for client	Browser, mobile, CLI
Secret	sb_secret_...	Backend only	Servers, Edge Functions
Legacy anon	JWT-based	Safe for client	Being deprecated
Legacy service_role	JWT-based	Backend only	Being deprecated

Key Rules:

• Secret keys return HTTP 401 if used in browser
• New keys support independent rotation without downtime
• Migrate from legacy keys when possible

See references/api-keys.md for migration guide and security practices.

Authentication SSR Rules

NEVER USE (DEPRECATED):

• Individual cookie methods: get(), set(), remove()
• Package: @supabase/auth-helpers-nextjs

ALWAYS USE:

• Package: @supabase/ssr
• Cookie methods: getAll() and setAll() ONLY
• Proxy (formerly Middleware) MUST call getUser() to refresh session
• Proxy MUST return supabaseResponse object

Important: As of Next.js 16+, use proxy.ts instead of middleware.ts. See https://nextjs.org/docs/app/api-reference/file-conventions/proxy

See references/auth-ssr-patterns.md for complete patterns.

RLS Policy Rules

• Always wrap functions in SELECT: (SELECT auth.uid()) not auth.uid()
• SELECT: USING only (no WITH CHECK)
• INSERT: WITH CHECK only (no USING)
• UPDATE: Both USING and WITH CHECK
• DELETE: USING only (no WITH CHECK)
• Always specify TO authenticated or TO anon
• Create indexes on ALL columns used in policies
• NEVER use FOR ALL - create 4 separate policies

See references/rls-policy-patterns.md for performance-optimized templates.

Database Function Rules

• DEFAULT: Use SECURITY INVOKER (safer than DEFINER)
• ALWAYS: Set search_path = '' for security
• USE: Fully qualified names (public.table_name)
• SPECIFY: Correct volatility (IMMUTABLE/STABLE/VOLATILE)
• AVOID: SECURITY DEFINER unless absolutely required

Edge Function Rules

• USE: Deno.serve (not old serve import)
• IMPORTS: Always use npm:/jsr:/node: prefix with version numbers
• SHARED: Place shared code in _shared/ folder
• FILES: Write only to /tmp directory
• NEVER: Use bare specifiers or cross-function dependencies

See references/edge-function-templates.md for complete templates.

Storage Rules

• Enable RLS on storage buckets
• Use signed URLs for private content
• Apply image transformations via URL parameters
• Leverage CDN for public assets

See references/storage-patterns.md for setup and patterns.

Workflow Decision Tree

User mentions database/Supabase work?
├─> Creating new tables?
│   └─> Use: Table Creation Workflow
├─> Creating RLS policies?
│   └─> Use: RLS Policy Workflow (references/rls-policy-patterns.md)
├─> Creating database function?
│   └─> Use: Database Function Workflow (references/sql-templates.md)
├─> Setting up Auth?
│   └─> Use: Auth SSR Workflow (references/auth-ssr-patterns.md)
├─> Creating Edge Function?
│   └─> Use: Edge Function Workflow (references/edge-function-templates.md)
├─> Setting up Storage?
│   └─> Use: Storage Workflow (references/storage-patterns.md)
├─> Next.js integration?
│   └─> Use: Next.js Patterns (references/nextjs-caveats.md)
└─> API key questions?
    └─> Use: API Keys Guide (references/api-keys.md)

Table Creation Workflow

When to use: Creating new database tables.

1. Design table structure:

   • id (UUID PRIMARY KEY)
   • created_at, updated_at (TIMESTAMPTZ)
   • created_by (UUID reference to auth.users or profiles)
   • Use snake_case for all identifiers
   • Add comments on all tables

2. Follow template:

   CREATE TABLE IF NOT EXISTS public.table_name (
       id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
       name TEXT NOT NULL,
       status TEXT DEFAULT 'active',
       created_by UUID REFERENCES auth.users(id),
       created_at TIMESTAMPTZ DEFAULT NOW(),
       updated_at TIMESTAMPTZ DEFAULT NOW()
   );
   
   COMMENT ON TABLE public.table_name IS 'Description';
   ALTER TABLE public.table_name ENABLE ROW LEVEL SECURITY;
   
   CREATE INDEX idx_table_name_status ON public.table_name(status);
   

3. Enable RLS and create policies

4. Create TypeScript types for type safety

See references/sql-templates.md for complete templates.

Auth SSR Quick Reference

Browser Client:

import { createBrowserClient } from '@supabase/ssr'

export function createClient() {
  return createBrowserClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_PUBLISHABLE_KEY!
  )
}

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_PUBLISHABLE_KEY!,
    {
      cookies: {
        getAll() { return cookieStore.getAll() },
        setAll(cookiesToSet) {
          try {
            cookiesToSet.forEach(({ name, value, options }) =>
              cookieStore.set(name, value, options)
            )
          } catch { /* Ignore in Server Components */ }
        },
      },
    }
  )
}

Proxy (Critical) - replaces middleware.ts:

// proxy.ts (at root or src/ directory)
import { createServerClient } from '@supabase/ssr'
import { NextResponse, type NextRequest } from 'next/server'

export async function proxy(request: NextRequest) {
  let supabaseResponse = NextResponse.next({ request })

  const supabase = createServerClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_PUBLISHABLE_KEY!,
    {
      cookies: {
        getAll() { return request.cookies.getAll() },
        setAll(cookiesToSet) {
          cookiesToSet.forEach(({ name, value }) =>
            request.cookies.set(name, value)
          )
          supabaseResponse = NextResponse.next({ request })
          cookiesToSet.forEach(({ name, value, options }) =>
            supabaseResponse.cookies.set(name, value, options)
          )
        },
      },
    }
  )

  // CRITICAL: Must call getUser() to refresh session
  await supabase.auth.getUser()

  return supabaseResponse  // MUST return supabaseResponse
}

RLS Policy Quick Reference

Operation	USING	WITH CHECK
SELECT	Required	Ignored
INSERT	Ignored	Required
UPDATE	Required	Required
DELETE	Required	Ignored

Example Policy:

CREATE POLICY "Users view own records"
ON public.table_name
FOR SELECT
TO authenticated
USING ((SELECT auth.uid()) = user_id);

Storage Quick Reference

Create bucket:

INSERT INTO storage.buckets (id, name, public)
VALUES ('avatars', 'avatars', false);

Storage policy:

CREATE POLICY "Users upload own avatar"
ON storage.objects
FOR INSERT
TO authenticated
WITH CHECK (
  bucket_id = 'avatars' AND
  (SELECT auth.uid())::text = (storage.foldername(name))[1]
);

Image transformation URL:

/storage/v1/object/public/bucket/image.jpg?width=200&height=200&resize=cover

Edge Function Quick Reference

import { createClient } from 'npm:@supabase/supabase-js@2'

Deno.serve(async (req: Request) => {
  if (req.method === 'OPTIONS') {
    return new Response('ok', {
      headers: {
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Headers': 'authorization, content-type',
      }
    })
  }

  // User-scoped client (respects RLS)
  const supabase = createClient(
    Deno.env.get('SUPABASE_URL')!,
    Deno.env.get('SUPABASE_PUBLISHABLE_KEY')!,
    { global: { headers: { Authorization: req.headers.get('Authorization')! } } }
  )

  // Admin client (bypasses RLS) - use SUPABASE_SECRET_KEY for admin operations
  // const adminClient = createClient(
  //   Deno.env.get('SUPABASE_URL')!,
  //   Deno.env.get('SUPABASE_SECRET_KEY')!
  // )

  // Your logic here

  return new Response(JSON.stringify({ success: true }), {
    headers: { 'Content-Type': 'application/json' }
  })
})

PostgreSQL Style Guide

• lowercase for SQL keywords
• snake_case for tables and columns
• Plural table names (users, orders)
• Singular column names (user_id, order_date)
• Schema prefix in queries (public.users)
• Comments on all tables
• ISO 8601 dates

Pre-Flight Checklist

Before ANY Supabase work:

• Using publishable key (sb_publishable_...) for client code
• Using secret key (sb_secret_...) only in secure backend
• Following table naming conventions
• Enabled RLS on tables
• Created indexes for policy columns
• Wrapped auth functions in SELECT
• Using @supabase/ssr with getAll/setAll
• Edge Functions using Deno.serve
• Imports have version numbers

Resources

Reference Files (Load as needed)

• references/api-keys.md - New API key system, migration guide
• references/storage-patterns.md - Storage setup, RLS, transformations
• references/nextjs-caveats.md - Next.js specific patterns and gotchas
• references/sql-templates.md - Complete SQL templates
• references/rls-policy-patterns.md - Performance-optimized RLS patterns
• references/auth-ssr-patterns.md - Complete Auth SSR implementation
• references/edge-function-templates.md - Edge function templates

Common Mistakes to Avoid

1. Using auth.uid() without wrapping in SELECT
2. Forgetting to create indexes on policy columns
3. Using SECURITY DEFINER by default
4. Mixing individual cookie methods (get/set/remove)
5. Using bare import specifiers in Edge Functions
6. Using secret keys in browser code
7. Not calling getUser() in proxy
8. Not returning supabaseResponse from proxy
9. Using middleware.ts instead of proxy.ts (deprecated in Next.js 16+)

Auth Providers Supported

Supabase Auth supports 20+ OAuth providers:

• Google, GitHub, GitLab, Bitbucket
• Apple, Microsoft, Facebook, Twitter
• Discord, Slack, Spotify, Twitch
• LinkedIn, Notion, Figma, Zoom
• Phone auth (Twilio, MessageBird, Vonage)
• Anonymous sign-ins
• Enterprise SSO (SAML)

See references/auth-ssr-patterns.md for provider setup.

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Skill Version: 2.0.0 Last Updated: 2025-01-01 Documentation: https://supabase.com/docs