From 5a6199b3b146c74663e8cb64529bbc7b160333e6 Mon Sep 17 00:00:00 2001
From: William Godbe <wigodbe@microsoft.com>
Date: Wed, 19 Aug 2026 09:15:51 -0700
Subject: [PATCH 1/3] Avoid duplicate framework builds from E2E publishes

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 src/Components/Directory.Build.targets                   | 9 +++++++++
 .../Microsoft.AspNetCore.Components.Testing.targets      | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/src/Components/Directory.Build.targets b/src/Components/Directory.Build.targets
index 4f109dbc2782..df854ba16fb1 100644
--- a/src/Components/Directory.Build.targets
+++ b/src/Components/Directory.Build.targets
@@ -11,6 +11,15 @@
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory)..\, Directory.Build.targets))\Directory.Build.targets" />
 
+  <!-- E2E app publishes use app-specific global properties while their framework dependencies
+       share the repository's normal build outputs. Do not create property-distinct dependency
+       builds that can concurrently rewrite those shared outputs. -->
+  <ItemDefinitionGroup Condition="'$(IsTestAssetProject)' == 'true'">
+    <ProjectReference>
+      <UndefineProperties>%(UndefineProperties);E2ECompileTestHarness;E2EAppMode;PublishDir;_E2EIsPublishing</UndefineProperties>
+    </ProjectReference>
+  </ItemDefinitionGroup>
+
   <!-- After ResolveReferences.targets (imported above) converts Reference to ProjectReference
        at evaluation time (which drops all custom metadata), re-apply metadata at evaluation
        time so it is always in effect for every build phase (Build, Publish, Razor, etc.):
diff --git a/src/Components/Testing/eng/targets/Microsoft.AspNetCore.Components.Testing.targets b/src/Components/Testing/eng/targets/Microsoft.AspNetCore.Components.Testing.targets
index 458727a0b307..01299f62d6e5 100644
--- a/src/Components/Testing/eng/targets/Microsoft.AspNetCore.Components.Testing.targets
+++ b/src/Components/Testing/eng/targets/Microsoft.AspNetCore.Components.Testing.targets
@@ -103,6 +103,10 @@
       <_E2EAppProjects Condition="'%(_E2EAppProjects.E2EAppMode)' == ''">
         <E2EAppMode>$(E2EAppMode)</E2EAppMode>
       </_E2EAppProjects>
+      <!-- These properties control test-host packaging and must not distinguish the app build. -->
+      <_E2EAppProjects>
+        <UndefineProperties>%(_E2EAppProjects.UndefineProperties);_E2EIsPublishing;E2EAppMode</UndefineProperties>
+      </_E2EAppProjects>
       <_E2ESourceAppProjects Include="@(_E2EAppProjects)" Condition="'%(_E2EAppProjects.E2EAppMode)' == 'build' or '%(_E2EAppProjects.E2EAppMode)' == 'all'" />
       <_E2EPublishPrimaryAppProjects Include="@(_E2EAppProjects)" Condition="'%(_E2EAppProjects.E2EAppMode)' == 'publish'" />
       <_E2EPublishSecondaryAppProjects Include="@(_E2EAppProjects)" Condition="'%(_E2EAppProjects.E2EAppMode)' == 'all' and '%(_E2EAppProjects.E2ENativeAot)' != 'true'" />

From 5bebd5bfa13414106dcae7b32b34688e1d85071e Mon Sep 17 00:00:00 2001
From: William Godbe <wigodbe@microsoft.com>
Date: Wed, 19 Aug 2026 09:50:04 -0700
Subject: [PATCH 2/3] Keep the E2E race workaround repo-local

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../targets/Microsoft.AspNetCore.Components.Testing.targets   | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/src/Components/Testing/eng/targets/Microsoft.AspNetCore.Components.Testing.targets b/src/Components/Testing/eng/targets/Microsoft.AspNetCore.Components.Testing.targets
index 01299f62d6e5..458727a0b307 100644
--- a/src/Components/Testing/eng/targets/Microsoft.AspNetCore.Components.Testing.targets
+++ b/src/Components/Testing/eng/targets/Microsoft.AspNetCore.Components.Testing.targets
@@ -103,10 +103,6 @@
       <_E2EAppProjects Condition="'%(_E2EAppProjects.E2EAppMode)' == ''">
         <E2EAppMode>$(E2EAppMode)</E2EAppMode>
       </_E2EAppProjects>
-      <!-- These properties control test-host packaging and must not distinguish the app build. -->
-      <_E2EAppProjects>
-        <UndefineProperties>%(_E2EAppProjects.UndefineProperties);_E2EIsPublishing;E2EAppMode</UndefineProperties>
-      </_E2EAppProjects>
       <_E2ESourceAppProjects Include="@(_E2EAppProjects)" Condition="'%(_E2EAppProjects.E2EAppMode)' == 'build' or '%(_E2EAppProjects.E2EAppMode)' == 'all'" />
       <_E2EPublishPrimaryAppProjects Include="@(_E2EAppProjects)" Condition="'%(_E2EAppProjects.E2EAppMode)' == 'publish'" />
       <_E2EPublishSecondaryAppProjects Include="@(_E2EAppProjects)" Condition="'%(_E2EAppProjects.E2EAppMode)' == 'all' and '%(_E2EAppProjects.E2ENativeAot)' != 'true'" />

From 8cb30b39679b848d8c68a1ebd4efecb019674a37 Mon Sep 17 00:00:00 2001
From: William Godbe <wigodbe@microsoft.com>
Date: Wed, 19 Aug 2026 10:17:09 -0700
Subject: [PATCH 3/3] Preserve E2E app publish properties

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 src/Components/Directory.Build.targets | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/Components/Directory.Build.targets b/src/Components/Directory.Build.targets
index df854ba16fb1..403e3f482bda 100644
--- a/src/Components/Directory.Build.targets
+++ b/src/Components/Directory.Build.targets
@@ -20,6 +20,14 @@
     </ProjectReference>
   </ItemDefinitionGroup>
 
+  <!-- PrepareE2EApps supplies these properties to the app itself. Preserve them on that edge,
+       then remove them when the app traverses its own project references. -->
+  <ItemGroup Condition="'$(IsTestAssetProject)' == 'true'">
+    <ProjectReference Update="@(ProjectReference->WithMetadataValue('E2EApp', 'true'))">
+      <UndefineProperties />
+    </ProjectReference>
+  </ItemGroup>
+
   <!-- After ResolveReferences.targets (imported above) converts Reference to ProjectReference
        at evaluation time (which drops all custom metadata), re-apply metadata at evaluation
        time so it is always in effect for every build phase (Build, Publish, Razor, etc.):