# Implement Domain Models

## Summary

Implement all domain model entities for the JDE Scoping Tool as defined in the domain-models specification. This establishes the core business entity layer for the .NET 10 migration, providing strongly-typed classes for JDE/CMS data representation, search criteria, and data transfer.

## Scope

### In Scope

- **Core entities** (4): Search, SearchCriteria, SearchStatus, SearchUpdate
- **Work order entities** (5): WorkOrder, WorkOrderStep, WorkOrderTime, WorkOrderComponent, WorkOrderRouting
- **Lot entities** (3): Lot, LotUsage, LotLocation
- **Reference entities** (8): Item, WorkCenter, ProfitCenter, Branch, JdeUser, StatusCode, FunctionCode, IBusinessUnit
- **Config entities** (3): DataUpdate, OrgHierarchy, RouteMaster
- **CMS entities** (1): MisData
- **Auth entities** (1): UserInfo
- **Support entities** (5): QueryTypes, TableSpec, ColumnSpec, UpdateTypes, StatusUpdate
- **Additional types** (4): POReceiver, POInspect, DcsLot, CamstarMO
- **ViewModels** for projections
- **Extension methods** for ToViewModel() conversions
- **JdeDateConverter** static helper for JDE date/time conversion

### Out of Scope

- Database repository implementations (covered by data-access spec)
- Service layer validation logic
- SignalR hub implementations (web-api-auth spec)
- Database schema (separate migrate-database-schema change)

## Motivation

The domain models are foundational to all other migration work. They provide:
- Type-safe representation of JDE/CMS manufacturing data
- Nullable reference type annotations for improved null safety
- System.Text.Json serialization compatibility for modern API communication
- Extension method projections for clean DTO separation

## Acceptance Criteria

1. All 52 requirements from `domain-models/spec.md` are implemented
2. Solution builds successfully with `dotnet build`
3. Nullable reference types enabled and all annotations applied per spec
4. All enums use `[JsonConverter(typeof(JsonStringEnumConverter))]`
5. JdeDateConverter handles edge cases (zero/invalid dates return null)
6. ToViewModel() extension methods exist for entities that require them
7. IBusinessUnit interface implemented by WorkCenter and ProfitCenter
8. `openspec validate implement-domain-models --strict` passes

## Dependencies

- Phase 1 (Solution Structure) - completed
- Phase 2 (Database Schema) - in progress, but domain models are independent

## Risks

| Risk | Mitigation |
|------|------------|
| Property name mismatch with legacy | Cross-reference spec against OLD/DataModel/Models/*.cs |
| Missing nullable annotations | Use spec's explicit nullable annotation list |
| JDE date conversion errors | Unit tests for edge cases (zero dates, invalid formats) |
| Serialization incompatibility | Test JSON round-trip for all entities |

## Related Specs

- `domain-models` - Primary specification for this change
- `database-schema` - Table definitions that entities map to
- `data-access` - Repositories that consume these entities