copilot-instructions: Instructions file for GitHub Copilot

Domain

• Business rules in domain (not in repositories)
• POCO classes without infra deps
• Invariants in constructor/factories
• Restricted setters
• Singular descriptive names (e.g., Invoice)
• Guid or long IDs
• Consider value objects (e.g., Cnpj, Email) and owned types

// Value object Email with validation
// Aggregate Order exposes AddItem() enforcing invariants
// Entity IDs as Guid
// No EF attributes in Domain

Mapping

• Centralized mapping (per entity/aggregate)
• Avoid persistence annotations in domain
• No lazy loading
• Prefer projections and explicit loading
• Concurrency control
• Soft-delete only with clear requirement
• Explicit constraints/indexes
• Auditing outside domain

// Fluent mapping class OrderMapping configures keys/indexes and relationships
// Use HasIndex(o => new { o.CustomerId, o.CreatedAt }).IncludeProperties(...)

Repositories/use cases

• Repositories per aggregate
• No business rules in repositories
• UoW/transactions in use case
• For read-heavy paths use projections and optimized queries when sensible

// IOrderRepository.GetRecentAsync returns DTOs via projection
// Application UseCase wraps Save changes in a transaction with retry on deadlock
// Batch operations use bulk APIs

Queries/DTOs

• Never return entities to the API
• Map to DTOs
• Paginate large lists
• Safe sortable filters

// Query projects to OrderListItemDto { Id, Number, Total, CreatedAt }
// Keyset pagination using (CreatedAt,Id)
// Allow sort by CreatedAt only

Security/observability

• No secrets in connection strings
• Minimal DB roles
• Structured logs with correlationId
• Metrics for pool/timeout/retries

// Connection string from secure vault
// DbContext logs include correlationId
// Metrics: connection pool usage, command timeouts, retries count