supabase

A set of guidelines for Supabase, a hosted service that provides user accounts, a PostgreSQL database, file storage, server-side functions, and live data updates.

In plain words
What is it for?
Use it when setting up Supabase in Next.js or React apps, adding authentication, defining database policies, uploading files, writing serverless functions, or subscribing to live changes.
Why use it?
It helps keep authentication and database access organized and protects records with row-level security, which controls which users can see or change each row.

Cursor rule

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/renvia-code/best-cursor-rules/supabase
Clone the repo
git clone --depth 1 https://github.com/Renvia-code/best-cursor-rules
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 1,982 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.01982
Opus 5 $0.00000 $0.00991
Sonnet 5 $0.00000 $0.00396
Haiku 4.5 $0.00000 $0.00198

Measured yesterday against content hash 6d721a76df31, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

supabase scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

rules/backends/supabase.mdc · 390 lines

How it starts

The opening of the file, as written. The whole thing — 390 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Supabase Best Practices

Overview

Feature Use Case
Auth User authentication and authorization
Database PostgreSQL with instant APIs
RLS Row Level Security for data protection
Edge Functions Serverless functions (Deno)
Realtime Live data subscriptions
Storage File uploads and management

Client Setup

Next.js / React

// lib/supabase/client.ts
import { createBrowserClient } from '@supabase/ssr'

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

Server-Side (Next.js App Router)

// lib/supabase/server.ts
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)
          )
        },
      },
    }
  )
}

Authentication

Sign Up / Sign In

const supabase = createClient()

// Sign up
const { data, error } = await supabase.auth.signUp({
  email: '[email protected]',
  password: 'secure-password',
})

// Sign in
const { data, error } = await supabase.auth.signInWithPassword({
  email: '[email protected]',
  password: 'secure-password',
})

// Sign in with OAuth
const { data, error } = await supabase.auth.signInWithOAuth({
  provider: 'google',
  options: {
    redirectTo: `${window.location.origin}/auth/callback`,
  },
})

// Sign out
await supabase.auth.signOut()

Get Current User

// Client-side
const { data: { user } } = await supabase.auth.getUser()

// Server-side (recommended for security)
const supabase = await createClient()
const { data: { user } } = await supabase.auth.getUser()

if (!user) {
  redirect('/login')
}

Read the full file on GitHub · 390 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 390 lines · 0 tokens per session scan A 6d721a76df31

Subscribe to this mod's changes

supabase is a cursor rule published in the GitHub repository Renvia-code/best-cursor-rules (12 stars, last pushed 9mo ago), licensed CC0-1.0. It costs nothing until one of its globs matches a file; then it loads 1,982 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.