Implements use cases across a NestJS backend with Drizzle ORM over PostgreSQL and a Next.js App Router frontend wired to that API. Use when the user asks to "implement a use case", "build the API", "create a REST endpoint", "write the data access layer", "build the page", or mentions NestJS modules, controllers, providers, Drizzle queries, repositories, or a Next.js frontend calling a NestJS backend.