[simonrozsival]

Context: #13481
Context: #13484

GetAndroidActivityName is a custom MSBuild task. It loads the merged AndroidManifest.xml through AndroidAppManifest (which also needs ReferenceAssemblyPaths to build a version resolver) just to return the first launchable user activity. Every custom task has to be hosted, loaded and kept multithreading-ready, and this one does nothing a single XPath query can't. This continues the effort to replace small tasks with plain MSBuild.

This adds a shared _GetAndroidLaunchableActivity target to Xamarin.Android.Common.targets. It reads $(IntermediateOutputPath)android\AndroidManifest.xml with the built-in <XmlPeek ProhibitDtd="true"/> and sets $(_AndroidLaunchableActivity). It keeps the selection order of AndroidAppManifest.GetLaunchableUserActivityName():

• Look only at the first <application>.
• Return the first <activity> whose <intent-filter> has the android.intent.category.LAUNCHER category.
• If there is none, fall back to the first matching <activity-alias>.
• Skip empty names and mono.android.__FastDevLauncher.

The query uses the (…)[1]/@android:name form because XmlPeek evaluates its query with XPathNavigator.Select(), so a scalar string(…) expression isn't allowed.

_AndroidComputeRunArguments (dotnet run), RunWithLogging and RunTests now depend on this target and copy its value into $(AndroidLaunchActivity) or $(TargetTestActivity) under the same conditions as before.

The target deliberately has no Inputs/Outputs. It produces only a property, and MSBuild can't infer an XmlPeek result for a skipped target, so the property would come back empty.

Removed: the GetAndroidActivityName task, both of its <UsingTask/> registrations (in Microsoft.Android.Sdk.Application.targets and Xamarin.Android.Common.Debugging.targets), and its two unit tests.

Behavior differences:

• If the merged manifest is missing, the activity is now empty instead of the task throwing.
• Like the C# implementation, the query checks only the LAUNCHER category and not the MAIN action.

Testing: not built or tested locally, because of disk-space constraints for this batch; CI validates this PR. The dotnet run/ComputeRunArguments, RunWithLogging and RunTests paths, including the activity-alias and instrumentation fallbacks, need CI coverage.

[Copilot]

🟡 Changes recommended

The new dependency causes all three device-selection test cases to fail with MSB4057 because their generated project does not define _GetAndroidLaunchableActivity.

2 open issues

• Stub the missing launcher-discovery target in the test fixture · New
• Restore coverage for launcher selection and project paths · New

What changed in this PR

Replaces the custom GetAndroidActivityName task with shared MSBuild XmlPeek queries, continuing the effort to simplify small build tasks and reduce task-hosting overhead.

Changes:

• Adds launcher discovery with activity-over-alias precedence and filtering for empty and FastDev launcher names.
• Routes run-argument computation, logging, and test launching through the shared target.
• Removes the custom task, its registrations, and its task-specific tests.

File	Description
src/​Xamarin.Android.Build.Tasks/​Xamarin.Android.Common.targets	Adds shared XPath-based launcher discovery.
src/​Xamarin.Android.Build.Tasks/​Tests/​Xamarin.Android.Build.Tests/​Tasks/​ResolveSdksTaskTests.cs	Removes the task’s parallel project-path tests.
src/​Xamarin.Android.Build.Tasks/​Tests/​Xamarin.Android.Build.Tests/​Tasks/​MultiThreadedMigrationTests.cs	Removes the task’s launcher-selection tests and unused import.
src/​Xamarin.Android.Build.Tasks/​Tasks/​GetAndroidActivityName.cs	Deletes the custom manifest-reading task.
src/​Xamarin.Android.Build.Tasks/​Microsoft.Android.Sdk/​targets/​Microsoft.Android.Sdk.Application.targets	Uses shared discovery for run arguments and logging.
src/​Xamarin.Android.Build.Debugging.Tasks/​Xamarin.Android.Common.Debugging.targets	Uses shared discovery for RunTests and removes task registration.

_{Review effort: Balanced}