Rabbehni

Rabbehni is a loyalty SaaS that lets any business — a café, a barber, a retail chain — run a real loyalty programme without building one: customers scan a QR code at the counter, the visit is recorded, and rewards or a game unlock instantly.

Context and problem. Loyalty is a solved problem for large chains with custom software and unsolved for everyone else. Building it as a SaaS raises three distinct hard problems at once. Tenancy: dozens of merchants share one database and must never see each other's customers. Trust: a check-in grants real economic value, so it cannot be something a client app can simply claim. Surface sprawl: the merchant needs a dashboard, the counter staff needs a fast scanner, and the customer needs a wallet — and the customer who just scanned a QR will not install an app, while the regular who returns weekly wants one.

Solution. A monorepo with a single NestJS 11 API and five client surfaces, none of which touches the database directly. The API is split by domain — checkin, games, rewards, redemptions, campaigns, billing, tenant, analytics, audit, localization — each a Nest module with a strict controller/service/Prisma split: controllers declare routes and validate DTOs, services hold all business logic, Prisma does data access and decides nothing. Shared concerns live in common as guards: authentication, tenant scoping, and subscription plan limits are enforced before a request reaches a service. Prisma models 26 entities across 9 versioned migrations against PostgreSQL 16. The web app is Next.js 16 with route groups per audience, and the customer app deliberately exists twice — as web for the just-scanned visitor and as an Expo app for the regular — both consuming exactly the same /api/me endpoints. A Socket.IO gateway pushes check-ins to merchant dashboards live.

Engineering and quality focus. The three-layer rule is the invariant the codebase is built around: no business logic in controllers, no req/res in services, no decisions in the data layer — which keeps services unit-testable without HTTP. Tenant isolation and plan enforcement are guards rather than per-endpoint checks, so a new module inherits them instead of re-implementing them and forgetting an edge case. Check-in validation is entirely server-side; the staff scanner submits a code and the API decides. The repository ships twelve chapters of technical documentation covering architecture, the data model, security, and functional journeys — plus seed scripts that bring up a complete demo dataset from an empty database.