Add .NET 10 validation package documentation to validation articles (#36015)

* Initial plan

* Add .NET 10 validation package documentation

Co-authored-by: wadepickett <[email protected]>

* Add comment to validation package include file

Co-authored-by: wadepickett <[email protected]>

* Fix copilot instructions violations: add frontmatter to include file and update ms.date

Co-authored-by: wadepickett <[email protected]>

* Update aspnetcore/includes/validation-package-net10.md

Removed extra space in include file.

* Fix nested moniker ranges in validation articles

Co-authored-by: wadepickett <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: wadepickett <[email protected]>
Co-authored-by: Wade Pickett <[email protected]>

Author: Copilot

aspnetcore/includes/validation-package-net10.md

@@ -0,0 +1,27 @@
+---
+title: .NET 10 validation package information
+ai-usage: ai-assisted
+ms.author: wpickett
+ms.date: 08/28/2025
+---
+<!-- USED in validation docs for .NET 10 -->
+
+## Validation in .NET 10
+
+In .NET 10, the unified validation APIs have been moved to the `Microsoft.Extensions.Validation` NuGet package. This change makes the validation APIs available outside of ASP.NET Core HTTP scenarios.
+
+To use the `Microsoft.Extensions.Validation` APIs:
+
+* Add the following package reference:
+
+  ```xml
+  <PackageReference Include="Microsoft.Extensions.Validation" Version="10.0.0" />
+  ```
+
+  The functionality remains the same but now requires an explicit package reference.
+
+* Register validation services with dependency injection:
+
+    ```csharp
+    builder.Services.AddValidation();
+    ```

aspnetcore/mvc/models/validation.md

@@ -5,7 +5,7 @@ description: Learn about model validation in ASP.NET Core MVC and Razor Pages.
 monikerRange: '>= aspnetcore-3.1'
 ms.author: tdykstra
 ms.custom: mvc
-ms.date: 05/7/2023
+ms.date: 08/28/2025
 uid: mvc/models/validation
 ---
 # Model validation in ASP.NET Core MVC and Razor Pages
@@ -16,6 +16,14 @@ This article explains how to validate user input in an ASP.NET Core MVC or Razor
 
 [View or download sample code](https://github.com/dotnet/AspNetCore.Docs/tree/main/aspnetcore/mvc/models/validation/samples) ([how to download](xref:fundamentals/index#how-to-download-a-sample)).
 
+:::moniker-end
+
+:::moniker range=">= aspnetcore-10.0"
+[!INCLUDE[](~/includes/validation-package-net10.md)]
+:::moniker-end
+
+:::moniker range=">= aspnetcore-7.0"
+
 ## Model state
 
 Model state represents errors that come from two subsystems: model binding and model validation. Errors that originate from [model binding](xref:mvc/models/model-binding) are generally data conversion errors. For example, an "x" is entered in an integer field. Model validation occurs after model binding and reports errors where data doesn't conform to business rules. For example, a 0 is entered in a field that expects a rating between 1 and 5.

aspnetcore/tutorials/first-mvc-app/validation.md

@@ -26,6 +26,13 @@ In this section:
 One of the design tenets of MVC is [DRY](https://wikipedia.org/wiki/Don%27t_repeat_yourself) ("Don't Repeat Yourself"). ASP.NET Core MVC encourages you to specify functionality or behavior only once, and then have it be reflected everywhere in an app. This reduces the amount of code you need to write and makes the code you do write less error prone, easier to test, and easier to maintain.
 
 The validation support provided by MVC and Entity Framework Core is a good example of the DRY principle in action. You can declaratively specify validation rules in one place (in the model class) and the rules are enforced everywhere in the app.
+:::moniker-end
+
+:::moniker range=">= aspnetcore-10.0"
+[!INCLUDE[](~/includes/validation-package-net10.md)]
+:::moniker-end
+
+:::moniker range=">= aspnetcore-9.0"
 
 ## Delete the previously edited data
 

aspnetcore/tutorials/razor-pages/validation.md

@@ -3,7 +3,7 @@ title: Part 8, add validation
 author: wadepickett
 description: Part 8 of tutorial series on Razor Pages.
 ms.author: wpickett
-ms.date: 06/23/2024
+ms.date: 08/28/2025
 uid: tutorials/razor-pages/validation
 ---
 # Part 8 of tutorial series on Razor Pages
@@ -27,6 +27,13 @@ The validation support provided by Razor Pages and Entity Framework is a good ex
 
 * Validation rules are declaratively specified in one place, in the model class.
 * Rules are enforced everywhere in the app.
+:::moniker-end
+
+:::moniker range=">= aspnetcore-10.0"
+[!INCLUDE[](~/includes/validation-package-net10.md)]
+:::moniker-end
+
+:::moniker range=">= aspnetcore-9.0"
 
 ## Add validation rules to the movie model