Ding Payments — Server

Backend API for Ding Payments: peer-to-peer NFC payments on the Stellar network (testnet MVP).

The server validates NFC payment requests against the payment-request.v1 contract, orchestrates the payment lifecycle, relays signed transactions to Stellar, and exposes transaction history.

Mobile client: The Expo app lives in a separate repository — Ding-Payments/ding-payments.

Tech stack

Layer	Technology
Framework	NestJS 11
Language	TypeScript 5.7 (strict)
ORM	Prisma + PostgreSQL
Database hosting	Supabase
Session auth	Supabase Auth (JWT)
Payment auth	WebAuthn (passkeys)
Blockchain	@stellar/stellar-sdk (Horizon + RPC)
Validation	class-validator, class-transformer
Config	@nestjs/config + Joi
API docs	@nestjs/swagger
Tests	Jest + Supertest

Prerequisites

• Node.js 20+ and npm
• A Supabase project with PostgreSQL (DATABASE_URL and DIRECT_URL)
• Stellar testnet access (default URLs are provided in .env.example)

Project setup

# Install dependencies
npm install

# Configure environment (Windows: copy .env.example .env)
cp .env.example .env
# Edit .env with your Supabase credentials and secrets

npm run prisma:generate
npm run prisma:migrate

# Start development server
npm run start:dev

The API is versioned under /v1. Swagger UI is available at /docs when the server is running.

Scripts

Command	Description
npm run start:dev	Start with hot reload
npm run start:prod	Run compiled build
npm run build	Compile TypeScript
npm run lint	Run ESLint
npm test	Unit tests
npm run test:e2e	End-to-end tests
npm run test:cov	Coverage report
npm run prisma:generate	Generate Prisma client
npm run prisma:migrate	Create/apply migrations
npm run prisma:studio	Open Prisma Studio
npm run prisma:seed	Seed development data

Project structure

Project structure:

ding-server/
├── prisma/                 # Schema, migrations, seed
├── docs/                   # Architecture, build plan, contracts
├── src/
│   ├── main.ts
│   ├── app.module.ts
│   ├── config/             # ConfigModule + env validation
│   ├── common/             # Filters, interceptors, decorators
│   ├── database/           # PrismaService (global)
│   ├── auth/               # Supabase JWT guards
│   ├── stellar/            # Horizon/RPC integration
│   ├── webauthn/           # Passkey verification
│   ├── contracts/          # payment-request.v1 contract
│   └── modules/
│       ├── users/
│       ├── payment-requests/
│       ├── payments/
│       └── transactions/
└── test/                   # E2E tests

Documentation

Document	Description
docs/ding-payments.md	Product vision and UX flows
docs/server-build-plan.md	Full server build plan (SRV tasks)
docs/server-build-plan-consolidated.md	Consolidated task reference

Supported assets (MVP)

Asset	Network	Notes
XLM	Stellar testnet	Native asset
USDC	Stellar testnet	Issuer via STELLAR_USDC_ISSUER in .env

Environment variables

Copy .env.example to .env and replace placeholders with your values. Variable groups:

• App — NODE_ENV, PORT, API_PREFIX, CORS_ORIGINS
• Database — DATABASE_URL, DIRECT_URL (Supabase PostgreSQL)
• Supabase Auth — SUPABASE_URL, SUPABASE_JWT_SECRET, SUPABASE_SERVICE_ROLE_KEY
• Stellar — network, Horizon/RPC URLs, USDC issuer, network passphrase
• WebAuthn — RP ID, name, and origin (must match the Expo client)
• Payments / rate limiting — submit timeouts, poll intervals, throttle settings

See .env.example for the full list with placeholder values.

Security notes

• Never commit .env or real secrets to the repository.
• Do not log JWTs, service role keys, or raw WebAuthn challenges.
• Hybrid auth model: Supabase session for API access + WebAuthn for payment approval.