Promotions Module

Summary

Product and category discounts for a point-of-sale system, with promotions moving through a strictly one-way lifecycle: Scheduled → Active → Finished. Modelling that as an explicit transition map rather than a status column with free-form updates is the difference between a domain rule and a convention somebody will eventually break.

The delivery is the actual point. Layered backend — routes, controllers, services — with Zod validating at the edge, unit tests against a mocked Prisma client, multi-stage Docker images, and a four-stage GitHub Actions pipeline that lints, tests, builds, and then boots the whole stack against a real PostgreSQL container for a smoke test. A green pipeline means the thing genuinely starts, not just that it compiles.