Turn XAML Incremental Hot Reload (XIHR) off by default

[StephaneDelcroix]

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Description

XAML Incremental Hot Reload (XIHR) was enabled by default for Debug builds on the net11.0 branch, which is causing issues. This PR makes XIHR opt-in instead of on-by-default.

Changes

• Microsoft.Maui.Controls.targets: EnableMauiIncrementalHotReload now defaults to false unless the developer explicitly sets it to true. Removed the Configuration == 'Debug' branch that defaulted it to true.
• Legacy XAML Hot Reload remains the default fallback (MauiXamlHotReload stays Legacy when XIHR is off).
• Updated a stale comment in MSBuildTests.cs that described XIHR as "on by default in Debug".

Notes

• The runtime feature switch default (IsIncrementalHotReloadEnabledByDefault) is already false, so this change makes the MSBuild default coherent with the runtime default end-to-end.
• To opt back in, set <EnableMauiIncrementalHotReload>true</EnableMauiIncrementalHotReload> in the project.
• Existing XIHR unit tests set the flag explicitly and are unaffected.

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 36832

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 36832"

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).
There may be pipelines that require an authorized user to comment /azp run to run.

[Copilot]

Pull request overview

This PR makes XAML Incremental Hot Reload (XIHR) opt-in by default by changing the MAUI Controls transitive targets to default EnableMauiIncrementalHotReload to false (instead of implicitly enabling it in Debug). This aligns the MSBuild-side default with the runtime feature switch default and preserves legacy XAML Hot Reload as the default fallback behavior.

Changes:

• Updated Microsoft.Maui.Controls.targets to default EnableMauiIncrementalHotReload to false when unset, removing the Debug-only implicit enablement.
• Kept legacy hot reload as the default fallback (MauiXamlHotReload defaults to Legacy unless XIHR is explicitly enabled).
• Updated the MSBuildTests.cs comment to reflect XIHR being off by default and explicitly pinned off in the test.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/Controls/tests/Xaml.UnitTests/MSBuild/MSBuildTests.cs	Updates a test comment to match the new XIHR default (opt-in) while continuing to pin XIHR off for the legacy fallback scenario.
src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets	Changes the default EnableMauiIncrementalHotReload behavior to false when unset and updates the explanatory comment; preserves MauiXamlHotReload default fallback to Legacy.

[rmarinho]

The samples builds seem to be failing

We will also need to backport to net11 preview7 branch

[kubaflo]

/backport to release/11.0.1xx-preview7

[github-actions]

Started backporting to release/11.0.1xx-preview7 (link to workflow run)