When to use - Backend work across src/Definition, src/Modules, src/Services, and src/AppHost (entities, DTOs, managers, controllers, EF, hosting). Usage - Architecture: Definition (entities/EF/Share/ServiceDefaults) - Modules (Managers + DTOs) - Services (controllers). Use Code First with <Nullable enable. - Entities: inherit EntityBase (Id, CreatedAt, UpdatedAt, IsDeleted); Id uses Guid v7 client-generated. Strings need max length; decimals set precision (10,2 or 18,6); enums require [Description]; prefer DateTimeOffset/DateOnly/TimeOnly. - Database: favor SQL Server (commercial) or PostgreS…