Document .NET Tool packaging breaking change for .NET 10 Preview 6 (#47925)

Author: Copilot

docs/core/compatibility/10.0.md

@@ -102,6 +102,7 @@ If you're migrating an app to .NET 10, the breaking changes listed here might af
 | Title | Type of change    | Introduced version |
 |-------|-------------------|--------------------|
 | [.NET CLI `--interactive` defaults to `true` in user scenarios](sdk/10.0/dotnet-cli-interactive.md) | Behavioral change | Preview 3 |
+| [.NET tool packaging invokes Publish instead of Build](sdk/10.0/dotnet-tool-pack-publish.md) | Behavioral change | Preview 6 |
 | [Default workload configuration from 'loose manifests' to 'workload sets' mode](sdk/10.0/default-workload-config.md) | Behavioral change | Preview 2 |
 | [`dotnet package list` performs restore](sdk/10.0/dotnet-package-list-restore.md) | Behavioral change | Preview 4 |
 | [`dotnet restore` audits transitive packages](sdk/10.0/nugetaudit-transitive-packages.md) | Behavioral change | Preview 3 |

docs/core/compatibility/sdk/10.0/dotnet-tool-pack-publish.md

@@ -0,0 +1,43 @@
+---
+title: "Breaking change: .NET tool packaging invokes Publish instead of Build"
+description: "Learn about the breaking change in the .NET 10 SDK where .NET tool packaging changed from invoking Build to Publish, affecting included assets."
+ms.date: 08/11/2025
+ai-usage: ai-assisted
+ms.custom: https://github.com/dotnet/docs/issues/47916
+---
+
+# .NET tool packaging invokes Publish instead of Build
+
+The .NET tool packaging process changed from invoking the MSBuild `Build` target to the `Publish` target (logically, not precisely). This means that assets that are included in `Publish` but not in `Build`, like WebSDK StaticWebAssets, now appear in tool packages by default. If you explicitly copied those files into place, you might begin to receive build diagnostics warning of duplicate copies.
+
+## Version introduced
+
+.NET 10 Preview 6
+
+## Previous behavior
+
+Previously when you ran `dotnet pack` on a project with `PackAsTool` set to `true`, it invoked the `Build` target, and only `Build`-created assets were included in the package.
+
+## New behavior
+
+Starting in .NET 10, the tool packaging process invokes the `Publish` target, which means `Publish`-created assets are included in the package. This includes StaticWebAssets and minified and trimmed application assets.
+
+## Type of breaking change
+
+This is a [behavioral change](../../categories.md#behavioral-change).
+
+## Reason for change
+
+This change enables the creation of optimized, platform-specific .NET Tool packages, and supports use cases like:
+
+- Self-contained tools.
+- Trimmed and AOT tools.
+- Tools that can eventually be used on platforms without an SDK or runtime installed.
+
+## Recommended action
+
+If your project is impacted, remove any explicit file copy customizations.
+
+## Affected APIs
+
+None.

docs/core/compatibility/toc.yml

@@ -108,6 +108,8 @@ items:
             items:
               - name: .NET CLI `--interactive` defaults to `true` in user scenarios
                 href: sdk/10.0/dotnet-cli-interactive.md
+              - name: .NET tool packaging invokes Publish instead of Build
+                href: sdk/10.0/dotnet-tool-pack-publish.md
               - name: "`dotnet restore` audits transitive packages"
                 href: sdk/10.0/nugetaudit-transitive-packages.md
               - name: Default workload configuration from 'loose manifests' to 'workload sets' mode