# DI Extension Class Standardization Design

## Purpose

Standardize the naming and location of DI extension classes across all projects to follow Microsoft best practices.

## Decisions

| Decision | Choice |
|----------|--------|
| File name | `DependencyInjection.cs` |
| Location | Project root |
| Namespace | `Microsoft.Extensions.DependencyInjection` |
| Class naming | `{ProjectName}DependencyInjection` |

## Changes By Project

### JdeScoping.Api
- **From:** `ServiceCollectionExtensions.cs` (root)
- **To:** `DependencyInjection.cs` (root)
- **Class:** `ServiceCollectionExtensions` → `ApiDependencyInjection`
- **Method:** `AddWebApi` (unchanged)

### JdeScoping.DataAccess
- **From:** `Extensions/ServiceCollectionExtensions.cs`
- **To:** `DependencyInjection.cs` (root)
- **Class:** `ServiceCollectionExtensions` → `DataAccessDependencyInjection`
- **Method:** `AddDataAccess` (unchanged)
- **Cleanup:** Delete empty `Extensions/` folder

### JdeScoping.DataSync
- **From:** `DependencyInjection/ServiceCollectionExtensions.cs`
- **To:** `DependencyInjection.cs` (root)
- **Class:** `ServiceCollectionExtensions` → `DataSyncDependencyInjection`
- **Method:** `AddDataSyncServices` (unchanged)
- **Cleanup:** Delete empty `DependencyInjection/` folder

### JdeScoping.ExcelIO
- **From:** `ServiceCollectionExtensions.cs` (root)
- **To:** `DependencyInjection.cs` (root)
- **Class:** `ServiceCollectionExtensions` → `ExcelIODependencyInjection`
- **Method:** `AddExcelIO` (unchanged)

### JdeScoping.Infrastructure
- **From:** `Extensions/InfrastructureServiceExtensions.cs`
- **To:** `DependencyInjection.cs` (root)
- **Class:** `InfrastructureServiceExtensions` → `InfrastructureDependencyInjection`
- **Method:** `AddInfrastructure` (unchanged)
- **Cleanup:** Delete empty `Extensions/` folder

## Host Project

No changes required. `Program.cs` already uses the extension methods correctly:

```csharp
builder.Services.AddDataAccess(builder.Configuration);
builder.Services.AddInfrastructure(builder.Configuration);
builder.Services.AddDataSyncServices(builder.Configuration);
builder.Services.AddExcelIO(builder.Configuration);
builder.Services.AddWebApi(builder.Configuration);
```

Since method names are unchanged and namespace is `Microsoft.Extensions.DependencyInjection`, the Host compiles without modification.

## File Template

```csharp
namespace Microsoft.Extensions.DependencyInjection;

public static class {ProjectName}DependencyInjection
{
    public static IServiceCollection Add{Feature}(
        this IServiceCollection services,
        IConfiguration configuration)
    {
        // registrations...
        return services;
    }
}
```

## Verification

After changes, run `dotnet build` to confirm all projects compile successfully.