Document DefaultItemExcludes for dotnet watch file exclusion

[Copilot]

Summary

.NET 10 SDK introduced support for using DefaultItemExcludes to exclude files from dotnet watch, preventing unwanted restarts. The existing documentation only covered the Watch="false" attribute approach.

Added new section documenting:

• DefaultItemExcludes property usage for folder/pattern exclusion
• App_Data folder example addressing unwanted page reloads in ASP.NET Core apps
• Multiple pattern exclusion syntax
• Comparison with Watch="false" attribute for choosing the right approach
• Cross-reference to MSBuild properties documentation

Example from the new section:

<PropertyGroup>
  <DefaultItemExcludes>$(DefaultItemExcludes);**/App_Data/**</DefaultItemExcludes>
</PropertyGroup>

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Mention use of DefaultItemExcludes to exclude items from dotnet watch</issue_title>
<issue_description>### Type of issue

Missing information

Description

In .NET 10, dotnet watch was improved to optionally exclude items from watch that are not relevant to the compilation.

As an example, this could include files in the App_Data folder of an ASP.NET Core application. If these files are updated as the app runs the developer will experience unwanted page reloads under .NET 9.

Under the .NET 10 SDK, something like this could be added to the project to prevent this behavior.

<PropertyGroup>
    <DefaultItemExcludes>$(DefaultItemExcludes);**/App_Data/**</DefaultItemExcludes>
</PropertyGroup>

The current documentation only details how to ignore Compile and EmbeddedResource items.

Page URL

https://learn.microsoft.com/en-us/dotnet/core/tools/dotnet-watch

Content source URL

https://github.com/dotnet/docs/blob/main/docs/core/tools/dotnet-watch.md

Document Version Independent Id

218d2a4d-2ff3-8e4d-1f06-bbb3710878fe

Platform Id

2254bd0c-661a-635e-3711-7e40a13c787d

Article author

@meaghanlewis

Metadata

• ID: 16f49f1b-261c-8cd0-a024-32c2535d0a0f
• PlatformId: 2254bd0c-661a-635e-3711-7e40a13c787d
• Service: dotnet-fundamentals

Related Issues

---

Associated WorkItem - 509069</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Mention use of DefaultItemExcludes to exclude items from dotnet watch #49904

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

---

Internal previews

📄 File	🔗 Preview link
docs/core/project-sdk/msbuild-props.md	MSBuild reference for .NET SDK projects
docs/core/tools/dotnet-watch.md	dotnet watch command

[Copilot]

Pull request overview

This PR adds documentation for the .NET 10 SDK feature that allows using DefaultItemExcludes property to exclude files and folders from dotnet watch monitoring. This addresses a gap where previously only the Watch="false" attribute approach was documented.

Key Changes:

• Added new section explaining DefaultItemExcludes property usage for excluding folders and file patterns
• Included practical example addressing the App_Data folder reload issue in ASP.NET Core apps
• Provided comparison between DefaultItemExcludes and Watch="false" attribute approaches