Work · Mobile product · APP/08 / since 2026
A simple interface, rules that hold
An iOS and Android application for proposing or joining an activity nearby: a public place, a duration, two participants, no photos and no biographies. Behind this reduced format, a system that guarantees a single seat, respects the server’s clock, survives network drops and has privacy enforced by the API. A Scopes product, in development.
The context
Having a coffee, going for a walk, visiting an exhibition: one person proposes, another joins, they meet in person. The journey must stay legible while handling the invisible situations: two bookings at the same instant, a network response arriving after a disconnection, an appointment expiring while a request waits. These situations shape the architecture as much as the screens do.
The work
Design of the journey, React Native and Expo application with a native map, Fastify and PostgreSQL API as a modular monolith, PostGIS for search, a support interface with its own server and its own SQL role, a static presentation site in 24 languages. The lifecycle of a proposal is a TypeScript module of states and transitions, verified without launching the application; the single seat is decided in a transaction that locks the proposal and rechecks the time after the lock.
What remains
A creation and participation journey implemented, a geographic search, testable privacy rules and a support tool. Notifications, qualification of external integrations and trials on physical devices come before mobile distribution. The product name is shared on request.
- Business rules isolated from the network and the database, tested to the millisecond
- Single seat guaranteed by a PostgreSQL lock, idempotent creations
- PostGIS geographic search on demand, no background tracking
- Privacy enforced in the API’s responses, not on screen