Document breaking change: ToolCommandName no longer set for non-tool packages

[Copilot]

Summary

Adds breaking change documentation for .NET 10 RC 1 where ToolCommandName is only set when PackAsTool is true, not for all projects.

Fixes #51739

Changes:

• Created breaking change article at docs/core/compatibility/sdk/10.0/toolcommandname-not-set.md
• Updated TOC and version index (10.0.md) under SDK and MSBuild section
• Classified as source-incompatible change

Recommended actions documented:

<!-- Option 1: Set explicitly -->
<PropertyGroup>
  <ToolCommandName>your-command-name</ToolCommandName>
</PropertyGroup>

<!-- Option 2: Convert to tool -->
<PropertyGroup>
  <PackAsTool>true</PackAsTool>
</PropertyGroup>

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Breaking change]: ToolCommandName is not set for non tool packages</issue_title>
<issue_description>### Description

We used to always set ToolCommandName for projects when packaged or built, regardless of whether or not they were a tool package. Now we only set it if PackAsTool is true and the package is a tool. Users may be surprised that this property is no longer set.

Please read the conversation in dotnet/sdk#51739

Version

.NET 10 RC 1

Previous behavior

ToolCommandName was always set.

New behavior

ToolCommandName is only set if its a tool package project.

Type of breaking change

• Binary incompatible: Existing binaries might encounter a breaking change in behavior, such as failure to load or execute, and if so, require recompilation.
• Source incompatible: When recompiled using the new SDK or component or to target the new runtime, existing source code might require source changes to compile successfully.
• Behavioral change: Existing binaries might behave differently at run time.

Reason for change

ToolCommandName does not make sense for non tool projects.

Recommended action

If you rely on this being set, please set the property explicitly or convert your project to a tool.

Feature area

SDK

Affected APIs

No response</issue_description>

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

Custom agent used: breakingchange-creator
Agent that specializes in creating breaking change articles

• Fixes [Breaking change]: ToolCommandName is not set for non tool packages #50272

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Internal previews

📄 File	🔗 Preview link
docs/core/compatibility/10.0.md	Breaking changes in .NET 10
docs/core/compatibility/sdk/10.0/toolcommandname-not-set.md	ToolCommandName not set for non-tool packages
docs/core/compatibility/toc.yml	docs/core/compatibility/toc

[Copilot]

Pull request overview

This PR documents a breaking change in .NET 10 RC 1 where the ToolCommandName MSBuild property is no longer automatically set for all projects, but only for projects that have PackAsTool set to true.

Key changes:

• Created comprehensive breaking change documentation following the standard template
• Updated TOC and version index to include the new breaking change article
• Provided clear workarounds for affected users

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docs/core/compatibility/sdk/10.0/toolcommandname-not-set.md	New breaking change article documenting the behavioral change and recommended actions
docs/core/compatibility/toc.yml	Added TOC entry for the new breaking change under SDK and MSBuild section
docs/core/compatibility/10.0.md	Added version index entry categorizing the change as source incompatible