Discoverly 🍽✨

Swipe. Match. Order. Pay with Stellar.

Discoverly is a Tinder-style food ordering app where users swipe through food items, match with their cravings, and pay seamlessly using the Stellar blockchain.

Built with:

• ⚛️ Expo (React Native) – Mobile app
• 🟢 Express.js – Backend API
• ⭐ Stellar – On-chain payment processing
• 🍃 MongoDB – Data persistence

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🚀 Overview

Discoverly reimagines food ordering with a swipe-based discovery experience.

Instead of scrolling through long menus:

• Users swipe right to like a dish
• Swipe left to skip
• Matched dishes go into their cart
• Payments are processed via Stellar blockchain

This allows:

• Fast crypto-native checkout
• Low transaction fees
• Borderless payments
• Transparent transaction tracking

---

🏗 Architecture

discoverly/
│
├── mobile/          → Expo (React Native) app
├── backend/         → Express.js API
├── stellar/         → Stellar payment utilities & services
└── README.md

Mobile (Expo)

• Swipe UI (card stack)
• User authentication
• Wallet connection
• Order flow
• Payment confirmation

Backend (Express)

• Auth & session management
• Restaurant & food listing APIs
• Match & cart management
• Order creation
• Stellar payment verification
• Webhook/event listeners

Stellar Layer

• Wallet creation (optional custodial)
• Payment intent generation
• Transaction submission
• Transaction verification
• Payment status tracking

---

⚙️ Tech Stack

Mobile

• Expo
• React Native
• React Navigation
• Axios
• Zustand (or preferred state manager)

Backend

• Node.js
• Express.js
• MongoDB + Mongoose
• Stellar SDK
• JWT Authentication

Blockchain

• Stellar Network
• Stellar SDK (JavaScript)
• Horizon API

---

🔑 Key Features

👤 User

• Register / Login
• Swipe-based food discovery
• Add to cart via match
• Checkout with Stellar
• View order history
• Track payment status

🍔 Restaurant

• Create food listings
• Manage availability
• Receive on-chain payments

💳 Payments (Stellar)

• Create payment request
• User signs transaction
• Submit to Stellar network
• Verify on backend
• Confirm order after verification

---

⭐ Stellar Integration

Network Configuration

import { Horizon, Networks } from "stellar-sdk";

const server = new Horizon.Server("https://horizon-testnet.stellar.org");

const networkPassphrase = Networks.TESTNET; 

---

💰 Payment Flow

1. User taps Checkout

2. Backend creates a payment intent

3. Backend returns:

   • Destination address
   • Amount
   • Memo (order ID)

4. User signs transaction

5. Transaction submitted to Stellar

6. Backend verifies:

   • Transaction hash
   • Destination
   • Memo
   • Amount

7. Order marked as PAID

---

🔄 Example Payment Verification

const tx = await server.transactions().transaction(txHash).call();

if (
  tx.memo === orderId &&
  tx.successful
) {
  // Mark order as paid
}

---

📦 Installation

1️⃣ Clone Repo

git clone https://github.com/your-username/discoverly.git
cd discoverly

---

2️⃣ Backend Setup

cd backend
npm install

Create .env:

PORT=5000
MONGO_URI=
JWT_SECRET=
STELLAR_SECRET_KEY=
STELLAR_NETWORK=testnet

Run:

npm run dev

---

3️⃣ Mobile Setup

cd mobile
npm install
npx expo start

Update API base URL inside config.

---

🔐 Environment Variables

Backend

Variable	Description
PORT	API port
DATABASE_URL	PostgreSQL connection URL
JWT_SECRET	Auth signing secret
STELLAR_NETWORK	testnet / public
STELLAR_HORIZON_URL	Optional Horizon override
STELLAR_DESTINATION_ADDRESS	Merchant receiving wallet
PAYMENT_RECONCILIATION_INTERVAL_MS	Reconciliation interval
PAYMENT_RECONCILIATION_BATCH_SIZE	Reconciliation batch size
PAYMENT_RECONCILIATION_STALE_MS	Reconciliation staleness threshold
PAYMENT_LISTENER_INTERVAL_MS	Listener polling interval
PAYMENT_LISTENER_BATCH_SIZE	Listener page size
STELLAR_PAYMENTS_START_CURSOR	Initial cursor (now recommended)
PAYMENT_EVENT_PROCESSOR_INTERVAL_MS	Event worker interval
PAYMENT_EVENT_PROCESSOR_BATCH_SIZE	Event worker batch size
PAYMENT_EVENT_RETRY_BASE_MS	Retry base delay
PAYMENT_EVENT_RETRY_MAX_MS	Retry max delay

---

📲 Swipe Logic

Food cards are fetched from:

GET /api/foods/discover

Swipe Right:

POST /api/match

Creates:

• Match record
• Adds to cart

Swipe Left:

• No persistence (optional tracking)

---

🧠 Order Flow

Swipe → Match → Cart → Checkout → Stellar Payment → Verification → Order Confirmed

Order statuses:

• PENDING
• AWAITING_PAYMENT
• PAID
• PREPARING
• COMPLETED
• CANCELLED

---

🔎 Security Considerations

• Never expose server secret key
• Verify all Stellar transactions on backend
• Validate memo & amount
• Use HTTPS in production
• Use rate limiting on payment endpoints
• Consider multi-sig for restaurant wallets (future improvement)

---

🌍 Deployment

Backend

• AWS / Railway / Render / DigitalOcean
• Use production Stellar network
• Secure environment variables

Stellar Cutover Runbook

1. Deploy the backend with PAYMENT_PROVIDER removed and Stellar env vars populated.
2. Set STELLAR_NETWORK=testnet and verify one end-to-end payment in staging.
3. Confirm async processors are running:
   • Listener inserts rows into payment_events
   • Event processor moves rows to processed
   • Reconciliation updates payment_transactions from submitted/pending to terminal status
4. Run duplicate-event test by posting the same webhook payload twice to /payments/webhooks/stellar; ensure only one event record is created.
5. Promote to production by switching STELLAR_NETWORK=public and (optionally) STELLAR_HORIZON_URL=https://horizon.stellar.org.

Rollback Plan

1. Pause payment traffic at the API gateway/load balancer.
2. Revert the backend deployment to the previous release artifact.
3. Keep payment_transactions and payment_events tables intact for audit continuity.
4. Re-enable traffic and reconcile any in-flight orders manually from persisted tx hashes.

Mobile

• Expo EAS build
• App Store / Play Store deployment

---

🔮 Future Improvements

• Non-custodial wallet integration
• QR payment support
• Restaurant analytics dashboard
• Stablecoin support (USDC on Stellar)
• Subscription meal plans
• On-chain loyalty points

---

🧪 Testing

Use Stellar Testnet:

• Fund accounts via Friendbot
• Switch to PUBLIC only in production

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🤝 Contributing

1. Fork the repo
2. Create feature branch
3. Commit changes
4. Open PR

Please follow:

• Clean commit messages
• Consistent code style
• Proper API documentation

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📜 License

MIT License

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💡 Vision

Discoverly combines the addictive swipe UX of modern dating apps with the power of blockchain-based payments to create a frictionless, borderless food discovery experience.

Food meets finance. Discovery meets decentralization.