Supabase RLS and Storage Implementation Guide

Status: ✅ Fully Implemented (November 13, 2025) Impact: Critical security and cost optimization features

Table of Contents

1. Overview
2. Row Level Security (RLS)
3. Supabase Storage
4. Setup Instructions
5. Testing
6. Architecture
7. Cost Analysis

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Overview

This implementation adds two critical features to the Archety backend:

1. Row Level Security (RLS): Database-level privacy enforcement
2. Supabase Storage: Simplified photo storage with automatic RLS

Why These Features Matter

RLS Prevents Data Leaks: - Privacy violations happen in the backend database, not the frontend - Protects against bugs in FastAPI code - Even if code has a bug (missing user_id filter), RLS prevents cross-user data access - Security enforced at the database layer (defense in depth)

Supabase Storage Simplifies Photo Management: - No AWS credentials or boto3 needed - Automatic RLS for photo privacy - Built-in image transformations (thumbnails) - Cheaper than S3 + CloudFront - Integrated with existing Supabase infrastructure

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Row Level Security (RLS)

What is RLS?

Row Level Security is a PostgreSQL feature that restricts which rows users can access based on policies. Supabase makes it easy to implement RLS using JWT authentication.

Example: Preventing Data Leaks

Without RLS (vulnerable):

# Bug in code - no user_id filter!
@router.get("/messages")
async def get_messages(chat_guid: str, db: Session):
    messages = db.query(Message).filter(
        Message.chat_guid == chat_guid
    ).all()  # ❌ Any user can query any chat_guid!

With RLS (protected):

CREATE POLICY "Users see only their own messages"
ON messages FOR SELECT
USING (
  conversation_id IN (
    SELECT id FROM conversations
    WHERE participants @> jsonb_build_array(
      (SELECT phone FROM users WHERE supabase_user_id = auth.uid())
    )
  )
);

Now the bug can't leak data - database enforces privacy!

RLS Policies Implemented

1. Users Table

-- Users can only view/update their own profile
CREATE POLICY "Users can view own profile"
ON public.users FOR SELECT
USING (supabase_user_id = auth.uid());

CREATE POLICY "Users can update own profile"
ON public.users FOR UPDATE
USING (supabase_user_id = auth.uid());

2. Messages Table

-- Users can only see messages from conversations they're part of
CREATE POLICY "Users can view own messages"
ON public.messages FOR SELECT
USING (
  conversation_id IN (
    SELECT id FROM conversations
    WHERE participants @> jsonb_build_array(
      (SELECT phone FROM users WHERE supabase_user_id = auth.uid())
    )
  )
);

3. OAuth Tokens Table

-- Users can only manage their own OAuth tokens
CREATE POLICY "Users can view own oauth tokens"
ON public.oauth_tokens FOR SELECT
USING (user_id = (SELECT id FROM users WHERE supabase_user_id = auth.uid()));

4. Relationship States, Boundaries

-- Users can only see their own relationship data
CREATE POLICY "Users can view own relationship states"
ON public.relationship_states FOR SELECT
USING (user_id = (SELECT id FROM users WHERE supabase_user_id = auth.uid()));

CREATE POLICY "Users can view own group boundaries"
ON public.group_boundaries FOR SELECT
USING (user_id = (SELECT id FROM users WHERE supabase_user_id = auth.uid()));

5. Usage Events, Transactions, Notifications

-- Users can only see their own usage and billing data
CREATE POLICY "Users can view own usage events"
ON public.usage_events FOR SELECT
USING (user_id = (SELECT id FROM users WHERE supabase_user_id = auth.uid()));

CREATE POLICY "Users can view own credit transactions"
ON public.credit_transactions FOR SELECT
USING (user_id = (SELECT id FROM users WHERE supabase_user_id = auth.uid()));

CREATE POLICY "Users can view own notifications"
ON public.proactive_notifications FOR SELECT
USING (user_id = (SELECT id FROM users WHERE supabase_user_id = auth.uid()));

How RLS Works

1. User authenticates via Twilio OTP
2. Backend creates Supabase session with JWT
3. User makes API request with Authorization: Bearer <token> header
4. Backend validates JWT and extracts supabase_user_id
5. Database queries use JWT via auth.uid() function
6. RLS policies filter results automatically

Service Role Bypass

The backend uses SUPABASE_SERVICE_KEY (service role) for: - Creating users - Admin operations - Background jobs - Photo uploads on behalf of users

Service role bypasses RLS, allowing backend to perform admin operations.

---

Supabase Storage

Why Supabase Storage?

Before (S3): - AWS credentials required - boto3 client setup - Manual encryption - S3 + CloudFront costs - No automatic RLS

After (Supabase Storage): - No AWS credentials needed - Simple Python client - Automatic encryption - Free tier (5GB storage) - Automatic RLS

Storage Structure

user-photos/ (private bucket)
├── {user_id}/
│   ├── {photo_id}/
│   │   └── {filename}.jpg
│   └── ...

user-photos-thumbnails/ (public bucket)
├── {user_id}/
│   ├── {photo_id}/
│   │   └── {filename}_thumb.webp
│   └── ...

Storage RLS Policies

-- Users can only upload photos to their own folder
CREATE POLICY "Users can upload own photos"
ON storage.objects FOR INSERT
WITH CHECK (
  bucket_id = 'user-photos' AND
  (storage.foldername(name))[1] = (
    SELECT u.id::text FROM users u WHERE u.supabase_user_id = auth.uid()
  )
);

-- Users can only view photos from their own folder
CREATE POLICY "Users can view own photos"
ON storage.objects FOR SELECT
USING (
  bucket_id = 'user-photos' AND
  (storage.foldername(name))[1] = (
    SELECT u.id::text FROM users u WHERE u.supabase_user_id = auth.uid()
  )
);

-- Users can delete their own photos
CREATE POLICY "Users can delete own photos"
ON storage.objects FOR DELETE
USING (
  bucket_id = 'user-photos' AND
  (storage.foldername(name))[1] = (
    SELECT u.id::text FROM users u WHERE u.supabase_user_id = auth.uid()
  )
);

Photo Upload Flow

# 1. User uploads photo via API
POST /photo/upload
Authorization: Bearer <jwt>
Content-Type: multipart/form-data

# 2. Backend stores in Supabase Storage
from app.storage.supabase_storage import get_supabase_storage

storage = get_supabase_storage()
result = storage.upload_photo(
    user_id=str(user.id),
    photo_id=photo_id,
    photo_data=image_bytes,
    content_type="image/jpeg"
)

# 3. Returns URL and path
{
    "photo_id": "abc123",
    "url": "https://xyz.supabase.co/storage/v1/object/public/user-photos/...",
    "path": "user_id/photo_id/filename.jpg"
}

# 4. Store metadata in database
photo_memory = PhotoMemory(
    id=photo_id,
    user_id=user.id,
    photo_url=result['url'],
    meta_data={'storage_path': result['path']}
)

Image Transformations

Supabase Storage supports automatic image transformations:

# Generate thumbnail
thumbnail_url = storage.generate_thumbnail(
    user_id=user_id,
    photo_id=photo_id,
    width=200,
    height=200
)
# Returns: .../photo.jpg?width=200&height=200&resize=cover&format=webp

---

Setup Instructions

1. Database Migrations

All RLS policies are applied via migrations:

# Migrations already applied in production
supabase/migrations/
├── 20251113_add_supabase_user_id_and_rls_policies.sql
└── 20251113_add_storage_rls_policies.sql

2. Environment Variables

Add to Railway (or .env):

# Supabase (required)
SUPABASE_URL=https://your-project.supabase.co
SUPABASE_ANON_KEY=your-anon-key
SUPABASE_SERVICE_KEY=your-service-role-key

# No longer needed:
# AWS_ACCESS_KEY_ID (removed)
# AWS_SECRET_ACCESS_KEY (removed)
# PHOTO_S3_BUCKET (removed)

3. Supabase Dashboard Setup

1. Create Storage Buckets:
2. Go to Storage → Create bucket
3. Name: user-photos (private)
4. Name: user-photos-thumbnails (public)
5. Max file size: 10MB

6. Allowed MIME types: image/jpeg, image/png, image/webp, image/heic

7. Enable Image Transformations:

8. Go to Storage → Settings
9. Enable "Image transformations"

10. This allows automatic thumbnail generation

11. Verify RLS Policies:

12. Go to Authentication → Policies
13. Should see policies for all tables
14. Go to Storage → Policies
15. Should see policies for both buckets

4. Update Frontend

Frontend needs to use JWT for API calls:

// After phone verification
const { access_token } = await verifyOTP(phone, code);

// Store token in HTTP-only cookie or localStorage
localStorage.setItem('access_token', access_token);

// Use in API calls
fetch('/api/user/profile', {
  headers: {
    'Authorization': `Bearer ${access_token}`
  }
});

5. Update Mac Mini Relay

Relay needs to use webhook secret:

# Mac mini relay
import requests

response = requests.post(
    "https://backend.archety.com/orchestrator/message",
    headers={
        "Authorization": f"Bearer {RELAY_WEBHOOK_SECRET}",
        "Content-Type": "application/json"
    },
    json=message_data
)

---

Testing

Run RLS Tests

# Run test suite
pytest tests/test_rls_policies.py -v

# Run summary
python tests/test_rls_policies.py

Manual Testing

1. Create two test users:

   curl -X POST https://backend/auth/verify/start \
     -d '{"phone": "+15551111111"}'
   
   curl -X POST https://backend/auth/verify/confirm \
     -d '{"phone": "+15551111111", "code": "123456"}'
   # Save access_token_a
   
   curl -X POST https://backend/auth/verify/start \
     -d '{"phone": "+15552222222"}'
   
   curl -X POST https://backend/auth/verify/confirm \
     -d '{"phone": "+15552222222", "code": "123456"}'
   # Save access_token_b
   

2. Test cross-user data access:

   # User A creates data
   curl -X PUT https://backend/user/profile \
     -H "Authorization: Bearer $access_token_a" \
     -d '{"name": "Alice", "pronouns": "she/her"}'
   
   # User A can read their own data
   curl https://backend/user/profile \
     -H "Authorization: Bearer $access_token_a"
   # ✅ Returns Alice's profile
   
   # User B cannot read User A's data
   curl https://backend/user/profile \
     -H "Authorization: Bearer $access_token_b"
   # ✅ Returns Bob's profile, NOT Alice's
   

3. Test photo storage RLS:

   # User A uploads photo
   curl -X POST https://backend/photo/upload \
     -H "Authorization: Bearer $access_token_a" \
     -F "file=@photo.jpg" \
     -F "user_phone=+15551111111"
   # ✅ Upload succeeds, photo stored in User A's folder
   
   # User B tries to access User A's photo
   # RLS prevents this at the storage level
   

---

Architecture

Authentication Flow

┌─────────┐      ┌──────────┐      ┌───────────┐      ┌──────────┐
│ User    │─────>│ Twilio   │─────>│ Backend   │─────>│ Supabase │
│ (Phone) │ OTP  │ Verify   │ Code │ FastAPI   │ JWT  │ Auth     │
└─────────┘      └──────────┘      └───────────┘      └──────────┘
                                           │
                                           │ Link internal user_id
                                           │ with supabase_user_id
                                           ↓
                                    ┌──────────────┐
                                    │ public.users │
                                    │ ┌──────────┐ │
                                    │ │ id (UUID)│ │
                                    │ │ phone    │ │
                                    │ │ supabase_│ │
                                    │ │ user_id  │ │
                                    │ └──────────┘ │
                                    └──────────────┘

Data Access Flow

┌──────────┐      ┌──────────┐      ┌──────────┐      ┌──────────┐
│ Frontend │─────>│ Backend  │─────>│ Supabase │─────>│ Database │
│          │ JWT  │ FastAPI  │ JWT  │ PostgREST│ RLS  │ Postgres │
└──────────┘      └──────────┘      └──────────┘      └──────────┘
                                                             │
                                                             │ RLS Policy:
                                                             │ WHERE supabase_user_id = auth.uid()
                                                             ↓
                                                      ┌──────────────┐
                                                      │ Only user's  │
                                                      │ data returned│
                                                      └──────────────┘

Photo Storage Flow

┌──────────┐      ┌──────────┐      ┌──────────┐      ┌──────────┐
│ User     │─────>│ Backend  │─────>│ Supabase │─────>│ Storage  │
│          │ Photo│ FastAPI  │ Upload│ Storage  │ RLS  │ Bucket   │
└──────────┘      └──────────┘      └──────────┘      └──────────┘
                                                             │
                                                             │ Path:
                                                             │ user_id/photo_id/filename.jpg
                                                             │
                                                             │ RLS Policy:
                                                             │ foldername[1] = user.id
                                                             ↓
                                                      ┌──────────────┐
                                                      │ Photo stored │
                                                      │ in user      │
                                                      │ folder only  │
                                                      └──────────────┘

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Cost Analysis

Before (S3 + Redis)

Service	Cost/Month	Notes
S3 Storage (5GB)	$0.12	$0.023 per GB
S3 Requests	$0.50	PUT/GET requests
CloudFront (CDN)	$1.00	Data transfer
Redis (JWT storage)	$5-10	Upstash or Railway
Total	$6.62-11.62

After (Supabase)

Service	Cost/Month	Notes
Supabase Storage (5GB)	$0	Free tier: 5GB
Supabase Auth	$0	Free tier: 50K MAU
Supabase Database	$0	Already using
Total	$0

Annual Savings

• Monthly savings: $6.62-11.62
• Annual savings: $79.44-139.44
• Plus: Simplified architecture, fewer moving parts

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Security Benefits

1. Defense in Depth

Even if backend code has bugs, RLS prevents data leaks:

# Bug in code
messages = db.query(Message).all()  # ❌ Missing user filter!

# But RLS prevents leak
# Only returns messages user has access to

2. Automatic Enforcement

No need to manually add WHERE user_id = ? to every query:

# Before (error-prone)
messages = db.query(Message).filter(
    Message.user_id == user_id  # Easy to forget!
).all()

# After (automatic)
messages = db.query(Message).all()  # RLS handles filtering

3. Audit Trail

All access controlled by database policies: - Easy to audit - Easy to update - Centralized security logic

---

Troubleshooting

RLS Blocking Legitimate Access

Symptom: Backend can't query user data

Solution: Check if backend is using service role key:

# ✅ Correct - bypasses RLS
client = create_client(
    settings.supabase_url,
    settings.supabase_service_key  # Service role key
)

# ❌ Wrong - subject to RLS
client = create_client(
    settings.supabase_url,
    settings.supabase_anon_key  # Anon key
)

Photos Not Uploading

Symptom: 403 Forbidden on photo upload

Solution: Check bucket exists and RLS policies are correct:

-- Verify bucket
SELECT * FROM storage.buckets WHERE name = 'user-photos';

-- Verify policies
SELECT * FROM storage.policies WHERE bucket_id = 'user-photos';

JWT Validation Failing

Symptom: 401 Unauthorized on API calls

Solution: Check token and expiry:

# Verify token
from app.identity.supabase_client import get_supabase_auth

auth = get_supabase_auth()
user_info = auth.verify_token(token)

if not user_info:
    # Token invalid or expired
    # User needs to refresh

---

Production Checklist

• Supabase URL and keys added to Railway
• RLS migrations applied
• Storage buckets created
• Frontend updated to use JWT
• Mac mini relay updated with webhook secret
• RLS tests passing
• Manual testing with two users completed
• Photo upload/download working
• Monitor Supabase dashboard for errors

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References

• Supabase RLS Documentation
• Supabase Storage Documentation
• PostgreSQL RLS Documentation
• Archety SUPABASE_SETUP.md

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Last Updated: November 13, 2025 Status: ✅ Production Ready