C# SDK: Update README, docs and samples for IModel API changes

Agent-Logs-Url: https://github.com/microsoft/Foundry-Local/sessions/8082508c-1338-48b2-bdd3-6c2c8e35e195

Co-authored-by: baijumeswani <12852605+baijumeswani@users.noreply.github.com>

Author: Copilot

samples/cs/GettingStarted/src/AudioTranscriptionExample/Program.cs

@@ -23,10 +23,10 @@
 var catalog = await mgr.GetCatalogAsync();
 
 
-// Get a model using an alias and select the CPU model variant
+// Get a model using an alias and select the CPU variant
 var model = await catalog.GetModelAsync("whisper-tiny") ?? throw new System.Exception("Model not found");
-var modelVariant = model.Variants.First(v => v.Info.Runtime?.DeviceType == DeviceType.CPU);
-model.SelectVariant(modelVariant);
+var cpuVariant = model.Variants.First(v => v.Info.Runtime?.DeviceType == DeviceType.CPU);
+model.SelectVariant(cpuVariant);
 
 
 // Download the model (the method skips download if already cached)

samples/cs/GettingStarted/src/ModelManagementExample/Program.cs

@@ -67,26 +67,26 @@
 
 
 // OPTIONAL: `model` can be used directly and `model.SelectedVariant` will be used as the default.
-//           You can explicitly select or use a specific ModelVariant if you want more control
+//           You can explicitly select a specific variant if you want more control
 //           over the device and/or execution provider used.
-//           Model and ModelVariant can be used interchangeably in methods such as
+//           Model and its variants can be used interchangeably in methods such as
 //           DownloadAsync, LoadAsync, UnloadAsync and GetChatClientAsync.
 //
 // Choices:
-//   - Use a ModelVariant directly from the catalog if you know the variant Id
-//     - `var modelVariant = await catalog.GetModelVariantAsync("qwen2.5-0.5b-instruct-generic-gpu:3")`
+//   - Use a variant directly from the catalog if you know the variant Id
+//     - `var variant = await catalog.GetModelVariantAsync("qwen2.5-0.5b-instruct-generic-gpu:3")`
 //
-//   - Get the ModelVariant from Model.Variants
-//     - `var modelVariant = model.Variants.First(v => v.Id == "qwen2.5-0.5b-instruct-generic-cpu:4")`
-//     - `var modelVariant = model.Variants.First(v => v.Info.Runtime?.DeviceType == DeviceType.GPU)`
-//       - optional: update selected variant in `model` using `model.SelectVariant(modelVariant);` if you wish to use
+//   - Get the variant from Model.Variants
+//     - `var variant = model.Variants.First(v => v.Id == "qwen2.5-0.5b-instruct-generic-cpu:4")`
+//     - `var variant = model.Variants.First(v => v.Info.Runtime?.DeviceType == DeviceType.GPU)`
+//       - optional: update selected variant in `model` using `model.SelectVariant(variant);` if you wish to use
 //                   `model` in your code.
 
 // For this example we explicitly select the CPU variant, and call SelectVariant so all the following example code
 // uses the `model` instance.
 Console.WriteLine("Selecting CPU variant of model");
-var modelVariant = model.Variants.First(v => v.Info.Runtime?.DeviceType == DeviceType.CPU);
-model.SelectVariant(modelVariant);
+var cpuVariant = model.Variants.First(v => v.Info.Runtime?.DeviceType == DeviceType.CPU);
+model.SelectVariant(cpuVariant);
 
 
 // Download the model (the method skips download if already cached)

sdk/cs/README.md

@@ -9,7 +9,7 @@ The Foundry Local C# SDK provides a .NET interface for running AI models locally
 - **Chat completions** — synchronous and `IAsyncEnumerable` streaming via OpenAI-compatible types
 - **Audio transcription** — transcribe audio files with streaming support
 - **Download progress** — wire up an `Action<float>` callback for real-time download percentage
-- **Model variants** — select specific hardware/quantization variants per model alias
+- **Model variants** — select specific hardware/quantization variants per model alias via the IModel interface
 - **Optional web service** — start an OpenAI-compatible REST endpoint (`/v1/chat_completions`, `/v1/models`)
 - **WinML acceleration** — opt-in Windows hardware acceleration with automatic EP download
 - **Full async/await** — every operation supports `CancellationToken` and async patterns
@@ -138,11 +138,14 @@ var cached = await catalog.GetCachedModelsAsync();
 
 // List models currently loaded in memory
 var loaded = await catalog.GetLoadedModelsAsync();
+
+// Check for a newer version of a model
+var latest = await catalog.GetLatestVersionAsync(model);
 ```
 
 ### Model Lifecycle
 
-Each `Model` wraps one or more `ModelVariant` entries (different quantizations, hardware targets). The SDK auto-selects the best variant, or you can pick one:
+Each `Model` wraps one or more variant entries (different quantizations, hardware targets). The SDK auto-selects the best variant, or you can pick one:
 
 ```csharp
 // Check and select variants
@@ -293,8 +296,8 @@ Key types:
 | [`FoundryLocalManager`](./docs/api/microsoft.ai.foundry.local.foundrylocalmanager.md) | Singleton entry point — create, catalog, web service |
 | [`Configuration`](./docs/api/microsoft.ai.foundry.local.configuration.md) | Initialization settings |
 | [`ICatalog`](./docs/api/microsoft.ai.foundry.local.icatalog.md) | Model catalog interface |
-| [`Model`](./docs/api/microsoft.ai.foundry.local.model.md) | Model with variant selection |
-| [`ModelVariant`](./docs/api/microsoft.ai.foundry.local.modelvariant.md) | Specific model variant (hardware/quantization) |
+| [`IModel`](./docs/api/microsoft.ai.foundry.local.imodel.md) | Model interface — shared by Model and ModelVariant |
+| [`Model`](./docs/api/microsoft.ai.foundry.local.model.md) | Model with variant selection (implementation detail) |
 | [`OpenAIChatClient`](./docs/api/microsoft.ai.foundry.local.openaichatclient.md) | Chat completions (sync + streaming) |
 | [`OpenAIAudioClient`](./docs/api/microsoft.ai.foundry.local.openaiaudioclient.md) | Audio transcription (sync + streaming) |
 | [`ModelInfo`](./docs/api/microsoft.ai.foundry.local.modelinfo.md) | Full model metadata record |