perigon-backendlisted

## 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 PostgreSQL; use foreign keys within a domain; avoid string-delimited lists (use arrays/JSON). Migrations via scripts/EFMigrations.ps1; files under Definition/EntityFramework/Migrations. - Data access: DbContexts live in Definition/EntityFramework/AppDbContext; default TenantDbFactory/UniversalDbFactory for creation. Prefer Queryable with Select projections; AsNoTracking by default; use EFCore.BulkExtensions for bulk ops. - Managers: place in src/Modules/{Mod}/Managers; inherit ManagerBase (generic when tied to entity) for DI. Do not return ActionResult or touch HttpContext; avoid manager-to-manager refs. Use base ops (FindAsync, ExistAsync, ListAsync, PageListAsync, InsertAsync, UpdateAsync, DeleteAsync, BulkInsertAsync, ExecuteInTransactionAsync). Throw BusinessException for business errors; keep third-party calls/helpers in share/services. - DTOs: store under src/Modules/{Mod}/Models/{