Domain, Structure & DDD

Lean Vertical Slice Architecture

InventoryAlert uses a Lean Vertical Slice approach. Business logic is co-located with the layer that owns the side effect — not forced into a generic Application layer.

Project Structure

Project	Responsibility	Key Namespaces
InventoryAlert.Domain	Pure entities, repository interfaces, DTOs, events, enums, and validators. Zero external dependencies.	Domain.Entities, Domain.Interfaces, Domain.DTOs, Domain.Events, Domain.Validators
InventoryAlert.Infrastructure	EF Core (PostgreSQL), DynamoDB, FinnhubClient, SQS queue, Redis, and UnitOfWork.	Infrastructure.Persistence, Infrastructure.External, Infrastructure.Messaging
InventoryAlert.Api	Thin REST controllers, service layer, FluentValidation, middleware, JWT auth, DI root.	Api.Controllers, Api.Services, Api.Configuration, Api.Middleware
InventoryAlert.Worker	Hangfire jobs, SQS listener, SQS event handlers.	Worker.ScheduledJobs, Worker.IntegrationEvents
InventoryAlert.UnitTests	xUnit + Moq + FluentAssertions. Covers all services, repositories.	-
InventoryAlert.IntegrationTests	EF Core InMemory repository tests.	-
InventoryAlert.E2ETests	Full HTTP roundtrip via RestSharp against running Docker stack.	-
InventoryAlert.ArchitectureTests	NetArchTest: Domain must have zero imports from Infrastructure/Api/Worker.	-

Dependency Direction

Rule: Domain must never reference Api, Infrastructure, or Worker. Enforced by InventoryAlert.ArchitectureTests on every build.

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Solution Folder Structure

InventoryManagementSystem/
├── InventoryAlert.Api/              ← Web layer
│   ├── Controllers/
│   │   ├── AuthController.cs
│   │   ├── PortfolioController.cs
│   │   ├── StocksController.cs
│   │   ├── MarketController.cs
│   │   ├── WatchlistController.cs
│   │   ├── AlertRulesController.cs
│   │   ├── NotificationsController.cs
│   │   └── EventsController.cs
│   ├── Services/
│   │   ├── AuthService.cs
│   │   ├── PortfolioService.cs
│   │   ├── StockDataService.cs
│   │   ├── AlertRuleService.cs
│   │   ├── WatchlistService.cs
│   │   ├── NotificationService.cs
│   │   └── EventService.cs
│   ├── Configuration/
│   │   └── ApiSettings.cs           ← Extends AppSettings with JwtSettings
│   ├── Middleware/
│   └── Program.cs
│
├── InventoryAlert.Domain/           ← Core (zero dependencies)
│   ├── Entities/Postgres/
│   │   ├── User.cs
│   │   ├── StockListing.cs          ← was Product.cs — global ticker catalog
│   │   ├── WatchlistItem.cs         ← Composite PK: (UserId, TickerSymbol)
│   │   ├── AlertRule.cs             ← AlertCondition enum
│   │   ├── Trade.cs                 ← was StockTransaction.cs — TradeType enum
│   │   ├── PriceHistory.cs
│   │   ├── StockMetric.cs           ← Cached basic financials (PK = TickerSymbol)
│   │   ├── EarningsSurprise.cs
│   │   ├── RecommendationTrend.cs
│   │   ├── InsiderTransaction.cs
│   │   └── Notification.cs
│   ├── Entities/Dynamodb/
│   │   ├── MarketNewsDynamoEntry.cs
│   │   └── CompanyNewsDynamoEntry.cs
│   ├── Events/
│   │   ├── EventEnvelope.cs
│   │   ├── EventTypes.cs
│   │   └── Payloads/
│   ├── Interfaces/
│   │   ├── IUnitOfWork.cs
│   │   ├── IStockListingRepository.cs
│   │   ├── ITradeRepository.cs
│   │   ├── IWatchlistItemRepository.cs
│   │   ├── IAlertRuleRepository.cs
│   │   ├── IPriceHistoryRepository.cs
│   │   ├── IStockMetricRepository.cs
│   │   ├── IEarningsSurpriseRepository.cs
│   │   ├── IRecommendationTrendRepository.cs
│   │   ├── IInsiderTransactionRepository.cs
│   │   ├── INotificationRepository.cs
│   │   ├── IFinnhubClient.cs
│   │   ├── IStockDataService.cs
│   │   ├── IPortfolioService.cs
│   │   ├── IAlertRuleService.cs
│   │   ├── IWatchlistService.cs
│   │   ├── INotificationService.cs
│   │   └── IAuthService.cs
│   ├── Configuration/
│   │   └── AppSettings.cs           ← Shared base settings
│   └── DTOs/
│       ├── AuthDTOs.cs
│       ├── PortfolioDTOs.cs
│       ├── AlertRuleDTOs.cs
│       ├── StockDTOs.cs
│       ├── MarketDTOs.cs
│       ├── CalendarDTOs.cs
│       ├── NotificationDTOs.cs
│       ├── EventDTOs.cs
│       ├── PagedResult.cs
│       └── PaginationParams.cs
│
├── InventoryAlert.Infrastructure/   ← Data access + external clients
│   ├── Persistence/Postgres/
│   │   ├── AppDbContext.cs
│   │   ├── DatabaseSeeder.cs
│   │   ├── Migrations/
│   │   ├── Configurations/          ← EF Core entity configs
│   │   └── Repositories/
│   │       ├── GenericRepository.cs
│   │       ├── UnitOfWork.cs
│   │       ├── StockListingRepository.cs
│   │       ├── TradeRepository.cs
│   │       ├── AlertRuleRepository.cs
│   │       ├── PriceHistoryRepository.cs
│   │       ├── StockMetricRepository.cs
│   │       ├── EarningsSurpriseRepository.cs
│   │       ├── RecommendationTrendRepository.cs
│   │       ├── InsiderTransactionRepository.cs
│   │       ├── NotificationRepository.cs
│   │       ├── UserRepository.cs
│   │       └── WatchlistItemRepository.cs
│   ├── Persistence/DynamoDb/
│   │   └── Repositories/
│   │       ├── MarketNewsDynamoRepository.cs
│   │       └── CompanyNewsDynamoRepository.cs
│   ├── External/Finnhub/
│   │   └── FinnhubClient.cs
│   ├── Messaging/
│   │   └── SqsService.cs
│   ├── Caching/
│   │   └── RedisHelper.cs
│   └── DependencyInjection.cs
│
├── InventoryAlert.Worker/           ← Background job engine
│   ├── ScheduledJobs/
│   │   ├── SyncPricesJob.cs
│   │   ├── SyncMetricsJob.cs
│   │   ├── SyncEarningsJob.cs
│   │   ├── SyncRecommendationsJob.cs
│   │   ├── SyncInsidersJob.cs
│   │   ├── NewsSyncJob.cs
│   │   ├── CleanupPriceHistoryJob.cs
│   │   ├── ProcessQueueJob.cs
│   └── IntegrationEvents/
│       ├── Routing/IntegrationMessageRouter.cs
│       └── Handlers/
│           ├── MarketPriceAlertHandler.cs
│           ├── LowHoldingsHandler.cs
│           └── DefaultHandler.cs
│
├── InventoryAlert.UnitTests/
├── InventoryAlert.IntegrationTests/
├── InventoryAlert.E2ETests/
└── InventoryAlert.ArchitectureTests/

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Placement Decision Reference

Type	Belongs In
Entity class	Domain/Entities/
Repository interface	Domain/Interfaces/
Service interface (shared)	Domain/Interfaces/
Request/Response DTO	Domain/DTOs/
FluentValidation validator	Domain/Validators/
SQS event payload	Domain/Events/Payloads/
EF Core configuration	Infrastructure/Persistence/Configurations/
Repository implementation	Infrastructure/Persistence/Repositories/
Caching / Messaging impl	Infrastructure/Caching/ or Infrastructure/Messaging/
Controller	Api/Controllers/
API-level service	Api/Services/
Scheduled job	Worker/ScheduledJobs/
SQS event handler	Worker/IntegrationEvents/Handlers/