From 70e3872590cfed862fbe696a4c3dab4c1fc06af8 Mon Sep 17 00:00:00 2001
From: Stephane Delcroix <stephane@delcroix.org>
Date: Thu, 12 Feb 2026 22:47:44 +0100
Subject: [PATCH 1/2] Add MauiXamlHotReload property for IDE communication

Introduces the MauiXamlHotReload MSBuild property to communicate to the IDE which
type of XAML Hot Reload implementation the application expects.

Values:
- Legacy (default): Traditional XAML Hot Reload
- SourceGen: Source generator-based XAML Hot Reload (experimental)

When SourceGen is selected, a warning (MAUI1002) is emitted indicating this
feature is experimental and not yet fully implemented.

This property exists to facilitate migration from legacy XAML Hot Reload to
the source generator-based approach. In a future release, Legacy may be
deprecated with SourceGen becoming the only supported mode.

Fixes #34027
---
 .../netstandard2.0/Microsoft.Maui.Controls.targets     | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets b/src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets
index 22d79df04b92..a0d183b7cb50 100644
--- a/src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets
+++ b/src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets
@@ -10,6 +10,9 @@
     <_MauiXamlInflator Condition="' $(MauiXamlInflator)' != '' ">$(MauiXamlInflator)</_MauiXamlInflator>
     <_MauiXamlInflator Condition=" '$(MauiXamlInflator)' == '' ">SourceGen</_MauiXamlInflator>
 
+    <!-- XAML Hot Reload mode for IDE communication (Legacy or SourceGen) -->
+    <MauiXamlHotReload Condition="'$(MauiXamlHotReload)' == ''">Legacy</MauiXamlHotReload>
+
     <EnableMauiXamlDiagnostics Condition=" '$(EnableMauiXamlDiagnostics)' == '' ">$(EnableMauiDiagnostics)</EnableMauiXamlDiagnostics>
     <EnableMauiXamlDiagnostics Condition=" '$(EnableMauiXamlDiagnostics)' == '' And '$(Configuration)' == 'Debug' ">$(EnableDiagnostics)</EnableMauiXamlDiagnostics>
     <EnableMauiXamlDiagnostics Condition=" '$(EnableMauiXamlDiagnostics)' == '' And '$(Configuration)' == 'Debug' ">true</EnableMauiXamlDiagnostics>
@@ -73,6 +76,13 @@
 			Condition="'$(_MauiTargetsImportedAgain)' == 'True'" />
 	</Target>
 
+	<!-- Warn when MauiXamlHotReload is set to SourceGen (not yet fully implemented) -->
+	<Target Name="_ValidateMauiXamlHotReload" BeforeTargets="_CheckForInvalidConfigurationAndPlatform" Condition="'$(MauiXamlHotReload)' == 'SourceGen'">
+		<Warning 
+			Code="MAUI1002"
+			Text="MauiXamlHotReload is set to 'SourceGen'. Source generator-based XAML Hot Reload is experimental and not yet fully implemented. Use at your own risk." />
+	</Target>
+
 	<Target Name="_ValidateMSBuild" BeforeTargets="_CheckForInvalidConfigurationAndPlatform">
 		<Error Code="XF003"
 			Text="Microsoft.Maui requires msbuild. xbuild is no longer supported."

From e1a31faee38454f3d2d9573e6720c351a0732c32 Mon Sep 17 00:00:00 2001
From: Stephane Delcroix <stephane@delcroix.org>
Date: Tue, 24 Feb 2026 21:05:07 +0100
Subject: [PATCH 2/2] Make MauiXamlHotReload validation case-insensitive

Add case-insensitive comparison for SourceGen/Legacy values and emit
MAUI1003 warning for unrecognized values.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../Microsoft.Maui.Controls.targets            | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets b/src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets
index a0d183b7cb50..43830be2d9aa 100644
--- a/src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets
+++ b/src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets
@@ -76,11 +76,21 @@
 			Condition="'$(_MauiTargetsImportedAgain)' == 'True'" />
 	</Target>
 
-	<!-- Warn when MauiXamlHotReload is set to SourceGen (not yet fully implemented) -->
-	<Target Name="_ValidateMauiXamlHotReload" BeforeTargets="_CheckForInvalidConfigurationAndPlatform" Condition="'$(MauiXamlHotReload)' == 'SourceGen'">
-		<Warning 
+	<!-- Validate MauiXamlHotReload values (case-insensitive) -->
+	<Target Name="_ValidateMauiXamlHotReload" BeforeTargets="_CheckForInvalidConfigurationAndPlatform">
+		<PropertyGroup>
+			<_MauiXamlHotReloadUpper>$([System.String]::Copy('$(MauiXamlHotReload)').Trim().ToUpperInvariant())</_MauiXamlHotReloadUpper>
+		</PropertyGroup>
+
+		<Warning
 			Code="MAUI1002"
-			Text="MauiXamlHotReload is set to 'SourceGen'. Source generator-based XAML Hot Reload is experimental and not yet fully implemented. Use at your own risk." />
+			Text="MauiXamlHotReload is set to 'SourceGen'. Source generator-based XAML Hot Reload is experimental and not yet fully implemented. Use at your own risk."
+			Condition="'$(_MauiXamlHotReloadUpper)' == 'SOURCEGEN'" />
+
+		<Warning
+			Code="MAUI1003"
+			Text="MauiXamlHotReload is set to an unrecognized value '$(MauiXamlHotReload)'. Supported values are 'Legacy' and 'SourceGen'."
+			Condition="'$(_MauiXamlHotReloadUpper)' != '' and '$(_MauiXamlHotReloadUpper)' != 'SOURCEGEN' and '$(_MauiXamlHotReloadUpper)' != 'LEGACY'" />
 	</Target>
 
 	<Target Name="_ValidateMSBuild" BeforeTargets="_CheckForInvalidConfigurationAndPlatform">