Feature: Dependency Injection & Keyed Registrations

Purpose

Make storage wiring predictable and scalable for .NET apps by supporting both a single default IStorage and multiple keyed storage registrations (multi-tenant, multi-region, mirroring):

register a single IStorage as the default storage for the app
register multiple storages side-by-side using keyed DI (multi-tenant, multi-region, mirroring, per-workload routing)
keep provider construction consistent via provider-specific Add*Storage...(...) extensions

Main Flows

Default registration

flowchart LR
  App --> DI[ServiceCollection]
  DI --> Default["IStorage (default)"]
  Default --> Provider[Concrete provider storage]

Keyed registration (multi-storage)

flowchart LR
  App --> DI[ServiceCollection]
  DI --> A["IStorage keyed: tenant-a"]
  DI --> B["IStorage keyed: tenant-b"]
  A --> ProviderA[Provider instance A]
  B --> ProviderB[Provider instance B]

Components

Core factory abstractions:

ManagedCode.Storage.Core/Providers/IStorageProvider.cs — provider contract used by the factory
ManagedCode.Storage.Core/Providers/IStorageFactory.cs — creates storages from options
ManagedCode.Storage.Core/Providers/StorageFactory.cs — resolves provider by options type and instantiates storages
ManagedCode.Storage.Core/Extensions/ServiceCollectionExtensions.cs — AddStorageFactory()

Provider registrations:

Each provider exposes Add*Storage(...) and Add*StorageAsDefault(...) (and keyed overloads).
Examples:

Keyed DI:

Uses built-in .NET keyed services:
- AddKeyedSingleton<T>(key, factory)
- resolve via GetRequiredKeyedService<T>(key) or [FromKeyedServices("key")]

Current Behavior

Default registrations bind IStorage to the provider-specific typed storage.
Keyed registrations allow multiple independent options sets and storage instances.
For cloud-drive providers, a “swap point” interface exists for testability:
- OneDrive: IOneDriveClient
- Google Drive: IGoogleDriveClient
- Dropbox: IDropboxClientWrapper

Tests

Definition of Done

README includes default + keyed DI examples.
Provider docs show minimal DI wiring.
Tests prove keyed/default registrations resolve the expected services.