diff --git a/documentation/general/dotnet-run-file.md b/documentation/general/dotnet-run-file.md
index 3fe98605ab2b..bdaf0176fdaa 100644
--- a/documentation/general/dotnet-run-file.md
+++ b/documentation/general/dotnet-run-file.md
@@ -65,6 +65,9 @@ Additionally, the implicit project file has the following customizations:
     This avoids including files like `./**/*.resx` in simple file-based apps where users usually don't expect that.
     See [multiple files](#multiple-files) for more details.
 
+  - `AssemblyName` and `RootNamespace` are set to the entry-point file name without extension (e.g., `Program` for `Program.cs`)
+    to ensure the binary name and generated code namespaces are not affected by the virtual project file name (which includes the `.cs` extension).
+
 ## Grow up
 
 When file-based programs reach an inflection point where build customizations in a project file are needed,
diff --git a/src/Cli/dotnet/Commands/Run/Api/RunApiCommand.cs b/src/Cli/dotnet/Commands/Run/Api/RunApiCommand.cs
index 8960eabd51cc..9504d64da1dd 100644
--- a/src/Cli/dotnet/Commands/Run/Api/RunApiCommand.cs
+++ b/src/Cli/dotnet/Commands/Run/Api/RunApiCommand.cs
@@ -75,7 +75,7 @@ public override RunApiOutput Execute()
             builder.CreateProjectInstance(
                 new ProjectCollection(),
                 errorReporter,
-                out _,
+                out var project,
                 out var evaluatedDirectives,
                 validateAllDirectives: true);
 
@@ -91,6 +91,7 @@ public override RunApiOutput Execute()
             return new RunApiOutput.Project
             {
                 Content = csprojWriter.ToString(),
+                ProjectPath = project.FullPath,
                 Diagnostics = diagnostics.ToImmutableArray(),
             };
         }
@@ -163,6 +164,7 @@ public sealed class Error : RunApiOutput
     public sealed class Project : RunApiOutput
     {
         public required string Content { get; init; }
+        public required string ProjectPath { get; init; }
         public required ImmutableArray<SimpleDiagnostic> Diagnostics { get; init; }
     }
 
diff --git a/src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.Generated.cs b/src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.Generated.cs
index 94e889267f86..d32604edcfeb 100644
--- a/src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.Generated.cs
+++ b/src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.Generated.cs
@@ -7,6 +7,7 @@ namespace Microsoft.DotNet.Cli.Commands.Run;
 partial class CSharpCompilerCommand
 {
     private IEnumerable<string> GetCscArguments(
+        string fileName,
         string fileNameWithoutExtension,
         string objDir,
         string binDir)
@@ -202,7 +203,7 @@ private IEnumerable<string> GetCscArguments(
             "/deterministic+",
             "/langversion:14.0",
             "/features:FileBasedProgram",
-            $"/analyzerconfig:{objDir}/{fileNameWithoutExtension}.GeneratedMSBuildEditorConfig.editorconfig",
+            $"/analyzerconfig:{objDir}/{fileName}.GeneratedMSBuildEditorConfig.editorconfig",
             $"/analyzerconfig:{SdkPath}/Sdks/Microsoft.NET.Sdk/analyzers/build/config/analysislevel_10_default.globalconfig",
             $"/analyzer:{SdkPath}/Sdks/Microsoft.NET.Sdk/targets/../analyzers/Microsoft.CodeAnalysis.CSharp.NetAnalyzers.dll",
             $"/analyzer:{SdkPath}/Sdks/Microsoft.NET.Sdk/targets/../analyzers/Microsoft.CodeAnalysis.NetAnalyzers.dll",
@@ -215,9 +216,9 @@ private IEnumerable<string> GetCscArguments(
             $"/analyzer:{DotNetRootPath}/packs/Microsoft.NETCore.App.Ref/{RuntimeVersion}/analyzers/dotnet/cs/System.Text.Json.SourceGeneration.dll",
             $"/analyzer:{DotNetRootPath}/packs/Microsoft.NETCore.App.Ref/{RuntimeVersion}/analyzers/dotnet/cs/System.Text.RegularExpressions.Generator.dll",
             $"{EntryPointFileFullPath}",
-            $"{objDir}/{fileNameWithoutExtension}.GlobalUsings.g.cs",
+            $"{objDir}/{fileName}.GlobalUsings.g.cs",
             $"{objDir}/.NETCoreApp,Version=v10.0.AssemblyAttributes.cs",
-            $"{objDir}/{fileNameWithoutExtension}.AssemblyInfo.cs",
+            $"{objDir}/{fileName}.AssemblyInfo.cs",
             "/warnaserror+:NU1605,SYSLIB0011",
         ];
     }
diff --git a/src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.cs b/src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.cs
index 675a638def76..d1c4c0c96a68 100644
--- a/src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.cs
+++ b/src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.cs
@@ -210,6 +210,7 @@ private void PrepareAuxiliaryFiles(out string rspPath)
         }
 
         string fileDirectory = Path.GetDirectoryName(EntryPointFileFullPath) ?? string.Empty;
+        string fileName = Path.GetFileName(EntryPointFileFullPath);
         string fileNameWithoutExtension = Path.GetFileNameWithoutExtension(EntryPointFileFullPath);
 
         // Note that Release builds won't go through this optimized code path because `-c Release` translates to global property `Configuration=Release`
@@ -231,7 +232,7 @@ private void PrepareAuxiliaryFiles(out string rspPath)
                 """);
         }
 
-        string globalUsings = Path.Join(objDir, $"{fileNameWithoutExtension}.GlobalUsings.g.cs");
+        string globalUsings = Path.Join(objDir, $"{fileName}.GlobalUsings.g.cs");
         if (ShouldEmit(globalUsings))
         {
             File.WriteAllText(globalUsings, /* lang=C#-test */ """
@@ -247,7 +248,7 @@ private void PrepareAuxiliaryFiles(out string rspPath)
                 """);
         }
 
-        string assemblyInfo = Path.Join(objDir, $"{fileNameWithoutExtension}.AssemblyInfo.cs");
+        string assemblyInfo = Path.Join(objDir, $"{fileName}.AssemblyInfo.cs");
         if (ShouldEmit(assemblyInfo))
         {
             File.WriteAllText(assemblyInfo, /* lang=C#-test */ $"""
@@ -277,7 +278,7 @@ private void PrepareAuxiliaryFiles(out string rspPath)
                 """);
         }
 
-        string editorconfig = Path.Join(objDir, $"{fileNameWithoutExtension}.GeneratedMSBuildEditorConfig.editorconfig");
+        string editorconfig = Path.Join(objDir, $"{fileName}.GeneratedMSBuildEditorConfig.editorconfig");
         if (ShouldEmit(editorconfig))
         {
             File.WriteAllText(editorconfig, $"""
@@ -366,6 +367,7 @@ private void PrepareAuxiliaryFiles(out string rspPath)
         if (ShouldEmit(rspPath))
         {
             IEnumerable<string> args = GetCscArguments(
+                fileName: fileName,
                 fileNameWithoutExtension: fileNameWithoutExtension,
                 objDir: objDir,
                 binDir: binDir);
diff --git a/src/Dotnet.Watch/Watch/Build/ProjectGraphFactory.cs b/src/Dotnet.Watch/Watch/Build/ProjectGraphFactory.cs
index 79aada5750ab..71f7fc7f1b02 100644
--- a/src/Dotnet.Watch/Watch/Build/ProjectGraphFactory.cs
+++ b/src/Dotnet.Watch/Watch/Build/ProjectGraphFactory.cs
@@ -107,8 +107,9 @@ private ProjectInstance CreateProjectInstance(string projectPath, Dictionary<str
     {
         if (!File.Exists(projectPath))
         {
-            var entryPointFilePath = Path.ChangeExtension(projectPath, ".cs");
-            if (!File.Exists(entryPointFilePath))
+            // The virtual project path is the entry-point file path with ".csproj" appended (e.g., "App.cs.csproj" for "App.cs").
+            if (!projectPath.EndsWith(".csproj", StringComparison.OrdinalIgnoreCase) ||
+                !File.Exists(projectPath = projectPath[..^".csproj".Length]))
             {
                 // `dotnet build` reports a warning when the reference project is missing.
                 // However, ProjectGraph doesn't allow us to return null to skip the project so we need to be stricter.
@@ -119,7 +120,7 @@ private ProjectInstance CreateProjectInstance(string projectPath, Dictionary<str
             var anyError = false;
 
             var projectInstance = VirtualProjectBuilder.CreateProjectInstance(
-                entryPointFilePath,
+                projectPath,
                 _targetFramework,
                 projectCollection,
                 (path, line, message) =>
diff --git a/src/Microsoft.DotNet.ProjectTools/VirtualProjectBuilder.cs b/src/Microsoft.DotNet.ProjectTools/VirtualProjectBuilder.cs
index 2356b742ea2c..12d818f8eac1 100644
--- a/src/Microsoft.DotNet.ProjectTools/VirtualProjectBuilder.cs
+++ b/src/Microsoft.DotNet.ProjectTools/VirtualProjectBuilder.cs
@@ -85,7 +85,7 @@ internal static string GetArtifactsPath(string entryPointFileFullPath)
     }
 
     public static string GetVirtualProjectPath(string entryPointFilePath)
-        => Path.ChangeExtension(entryPointFilePath, ".csproj");
+        => entryPointFilePath + ".csproj";
 
     /// <summary>
     /// Obtains a temporary subdirectory for file-based app artifacts, e.g., <c>/tmp/dotnet/runfile/</c>.
@@ -375,7 +375,7 @@ ProjectRootElement CreateProjectRootElement(string projectFileText, ProjectColle
                 using var reader = new StringReader(projectFileText);
                 using var xmlReader = XmlReader.Create(reader);
                 var projectRoot = ProjectRootElement.Create(xmlReader, projectCollection);
-                projectRoot.FullPath = Path.ChangeExtension(EntryPointFileFullPath, ".csproj");
+                projectRoot.FullPath = GetVirtualProjectPath(EntryPointFileFullPath);
                 return projectRoot;
             }
         }
@@ -465,6 +465,7 @@ internal static void WriteProjectFile(
         if (isVirtualProject)
         {
             Debug.Assert(!string.IsNullOrWhiteSpace(artifactsPath));
+            Debug.Assert(entryPointFilePath is not null);
 
             // Note that ArtifactsPath needs to be specified before Sdk.props
             // (usually it's recommended to specify it in Directory.Build.props
@@ -475,8 +476,10 @@ internal static void WriteProjectFile(
                   <PropertyGroup>
                     <IncludeProjectNameInArtifactsPaths>false</IncludeProjectNameInArtifactsPaths>
                     <ArtifactsPath>{EscapeValue(artifactsPath)}</ArtifactsPath>
-                    <PublishDir>artifacts/$(MSBuildProjectName)</PublishDir>
-                    <PackageOutputPath>artifacts/$(MSBuildProjectName)</PackageOutputPath>
+                    <AssemblyName>{EscapeValue(Path.GetFileNameWithoutExtension(entryPointFilePath))}</AssemblyName>
+                    <RootNamespace>$(AssemblyName)</RootNamespace>
+                    <PublishDir>artifacts/$(AssemblyName)</PublishDir>
+                    <PackageOutputPath>artifacts/$(AssemblyName)</PackageOutputPath>
                     <FileBasedProgram>true</FileBasedProgram>
                     <FileBasedProgramsItemMapping>{CSharpDirective.IncludeOrExclude.DefaultMappingString}</FileBasedProgramsItemMapping>
                     <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.props b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.props
index ccb497097cd2..98363805e375 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.props
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.props
@@ -131,7 +131,7 @@ Copyright (c) .NET Foundation. All rights reserved.
     <!-- <WarningsAsErrors>$(WarningsAsErrors);NU1605</WarningsAsErrors> -->
 
     <!-- Implicitly set UserSecretsId for file-based apps. -->
-    <_ImplicitFileBasedProgramUserSecretsId Condition="'$(FileBasedProgram)' == 'true'">$(MSBuildProjectName)-$([MSBuild]::StableStringHash($(MSBuildProjectFullPath.ToLowerInvariant()), 'Sha256'))</_ImplicitFileBasedProgramUserSecretsId>
+    <_ImplicitFileBasedProgramUserSecretsId Condition="'$(FileBasedProgram)' == 'true'">$(AssemblyName)-$([MSBuild]::StableStringHash($(MSBuildProjectFullPath.ToLowerInvariant()), 'Sha256'))</_ImplicitFileBasedProgramUserSecretsId>
     <UserSecretsId Condition="'$(FileBasedProgram)' == 'true' and '$(UserSecretsId)' == ''">$(_ImplicitFileBasedProgramUserSecretsId)</UserSecretsId>
   </PropertyGroup>
 
diff --git a/test/dotnet-watch.Tests/Build/ProjectGraphFactoryTests.cs b/test/dotnet-watch.Tests/Build/ProjectGraphFactoryTests.cs
index 755009e2afe9..237c860329c8 100644
--- a/test/dotnet-watch.Tests/Build/ProjectGraphFactoryTests.cs
+++ b/test/dotnet-watch.Tests/Build/ProjectGraphFactoryTests.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Microsoft.DotNet.FileBasedPrograms;
+using Microsoft.DotNet.ProjectTools;
 
 namespace Microsoft.DotNet.Watch.UnitTests;
 
@@ -45,7 +46,7 @@ public void VirtualProject()
         Assert.NotNull(graph);
 
         var root = graph.Graph.GraphRoots.Single();
-        Assert.Equal(Path.ChangeExtension(entryPointFilePath, ".csproj"), root.ProjectInstance.FullPath);
+        Assert.Equal(VirtualProjectBuilder.GetVirtualProjectPath(entryPointFilePath), root.ProjectInstance.FullPath);
     }
 
     [Fact]
@@ -97,7 +98,7 @@ public void VirtualProject_ProjectDirective()
         Assert.NotNull(graph);
 
         AssertEx.SequenceEqual(
-            [projectPath, Path.ChangeExtension(entryPointFilePath, ".csproj")],
+            [projectPath, VirtualProjectBuilder.GetVirtualProjectPath(entryPointFilePath)],
             graph.Graph.ProjectNodesTopologicallySorted.Select(p => p.ProjectInstance.FullPath));
     }
 }
diff --git a/test/dotnet.Tests/CommandTests/Project/Convert/DotnetProjectConvertTests.cs b/test/dotnet.Tests/CommandTests/Project/Convert/DotnetProjectConvertTests.cs
index adcb13515a90..fc2676b8d35d 100644
--- a/test/dotnet.Tests/CommandTests/Project/Convert/DotnetProjectConvertTests.cs
+++ b/test/dotnet.Tests/CommandTests/Project/Convert/DotnetProjectConvertTests.cs
@@ -982,7 +982,7 @@ public void UserSecretsId_Overridden_ViaDirectoryBuildProps()
     [Theory, CombinatorialData]
     public void UserSecretsId_Overridden_SameAsImplicit(bool hasDirective, bool hasDirectiveBuildProps)
     {
-        const string implicitValue = "$(MSBuildProjectName)-$([MSBuild]::StableStringHash($(MSBuildProjectFullPath.ToLowerInvariant()), 'Sha256'))";
+        const string implicitValue = "$(AssemblyName)-$([MSBuild]::StableStringHash($(MSBuildProjectFullPath.ToLowerInvariant()), 'Sha256'))";
 
         var testInstance = _testAssetsManager.CreateTestDirectory();
         File.WriteAllText(Path.Join(testInstance.Path, "Program.cs"), $"""
diff --git a/test/dotnet.Tests/CommandTests/Run/RunFileTests.cs b/test/dotnet.Tests/CommandTests/Run/RunFileTests.cs
index c908a7142cf2..d16b5f8fafcf 100644
--- a/test/dotnet.Tests/CommandTests/Run/RunFileTests.cs
+++ b/test/dotnet.Tests/CommandTests/Run/RunFileTests.cs
@@ -1903,6 +1903,23 @@ public void EmbeddedResource_AlongsideProj([CombinatorialValues("sln", "slnx", "
             .And.HaveStdOut(considered ? "Resource not found" : "[MyString, TestValue]");
     }
 
+    [Fact]
+    public void Restore_NonExistentPackage()
+    {
+        var testInstance = _testAssetsManager.CreateTestDirectory();
+        var programFile = Path.Join(testInstance.Path, "Program.cs");
+        File.WriteAllText(programFile, """
+            #:package Microsoft.ThisPackageDoesNotExist@1.0.0
+            Console.WriteLine();
+            """);
+
+        new DotnetCommand(Log, "restore", "Program.cs")
+            .WithWorkingDirectory(testInstance.Path)
+            .Execute()
+            .Should().Fail()
+            .And.HaveStdOutContaining("Program.cs.csproj : error NU1101");
+    }
+
     [Fact]
     public void NoRestore_01()
     {
@@ -2121,7 +2138,7 @@ class C;
             .Execute()
             .Should().Fail()
             .And.HaveStdErr(string.Format(CliCommandStrings.RunCommandExceptionUnableToRun,
-                Path.ChangeExtension(programFile, ".csproj"),
+                VirtualProjectBuilder.GetVirtualProjectPath(programFile),
                 ToolsetInfo.CurrentTargetFrameworkVersion,
                 "Library"));
     }
@@ -2167,7 +2184,7 @@ class C;
             .Execute()
             .Should().Fail()
             .And.HaveStdErr(string.Format(CliCommandStrings.RunCommandExceptionUnableToRun,
-                Path.ChangeExtension(programFile, ".csproj"),
+                VirtualProjectBuilder.GetVirtualProjectPath(programFile),
                 ToolsetInfo.CurrentTargetFrameworkVersion,
                 "Library"));
     }
@@ -2196,7 +2213,7 @@ class C;
             .Execute()
             .Should().Fail()
             .And.HaveStdErr(string.Format(CliCommandStrings.RunCommandExceptionUnableToRun,
-                Path.ChangeExtension(programFile, ".csproj"),
+                VirtualProjectBuilder.GetVirtualProjectPath(programFile),
                 ToolsetInfo.CurrentTargetFrameworkVersion,
                 "Module"));
     }
@@ -2317,7 +2334,7 @@ public void Build_AppContainerExe()
             .Execute()
             .Should().Fail()
             .And.HaveStdErr(string.Format(CliCommandStrings.RunCommandExceptionUnableToRun,
-                Path.ChangeExtension(programFile, ".csproj"),
+                VirtualProjectBuilder.GetVirtualProjectPath(programFile),
                 ToolsetInfo.CurrentTargetFrameworkVersion,
                 "AppContainerExe"));
     }
@@ -3980,6 +3997,7 @@ namespace Microsoft.DotNet.Cli.Commands.Run;
             partial class CSharpCompilerCommand
             {
                 private IEnumerable<string> GetCscArguments(
+                    string fileName,
                     string fileNameWithoutExtension,
                     string objDir,
                     string binDir)
@@ -4062,13 +4080,20 @@ private IEnumerable<string> GetCscArguments(
                 needsInterpolation = true;
             }
 
-            // Use variable file name.
+            // Use variable file path.
             if (rewritten.Contains(entryPointPathNormalized, StringComparison.OrdinalIgnoreCase))
             {
                 rewritten = rewritten.Replace(entryPointPathNormalized, "{" + nameof(CSharpCompilerCommand.EntryPointFileFullPath) + "}", StringComparison.OrdinalIgnoreCase);
                 needsInterpolation = true;
             }
 
+            // Use variable file name.
+            if (rewritten.Contains(fileName, StringComparison.OrdinalIgnoreCase))
+            {
+                rewritten = rewritten.Replace(fileName, "{fileName}", StringComparison.OrdinalIgnoreCase);
+                needsInterpolation = true;
+            }
+
             // Use variable program name.
             if (rewritten.Contains(programName, StringComparison.OrdinalIgnoreCase))
             {
@@ -5520,6 +5545,7 @@ public void Api()
             Console.WriteLine();
             """);
 
+        var projectPath = VirtualProjectBuilder.GetVirtualProjectPath(programPath);
         new DotnetCommand(Log, "run-api")
             .WithStandardInput($$"""
                 {"$type":"GetProject","EntryPointFileFullPath":{{ToJson(programPath)}},"ArtifactsPath":"/artifacts"}
@@ -5533,8 +5559,10 @@ public void Api()
                       <PropertyGroup>
                         <IncludeProjectNameInArtifactsPaths>false</IncludeProjectNameInArtifactsPaths>
                         <ArtifactsPath>/artifacts</ArtifactsPath>
-                        <PublishDir>artifacts/$(MSBuildProjectName)</PublishDir>
-                        <PackageOutputPath>artifacts/$(MSBuildProjectName)</PackageOutputPath>
+                        <AssemblyName>Program</AssemblyName>
+                        <RootNamespace>$(AssemblyName)</RootNamespace>
+                        <PublishDir>artifacts/$(AssemblyName)</PublishDir>
+                        <PackageOutputPath>artifacts/$(AssemblyName)</PackageOutputPath>
                         <FileBasedProgram>true</FileBasedProgram>
                         <FileBasedProgramsItemMapping>.cs=Compile;.resx=EmbeddedResource;.json=None;.razor=Content</FileBasedProgramsItemMapping>
                         <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
@@ -5579,7 +5607,7 @@ public void Api()
 
                     </Project>
 
-                    """)}},"Diagnostics":[]}
+                    """)}},"ProjectPath":{{ToJson(projectPath)}},"Diagnostics":[]}
                 """);
     }
 
@@ -5609,6 +5637,7 @@ public void Api_Evaluation()
         var bPath = Path.Join(testInstance.Path, "B.cs");
         File.WriteAllText(bPath, "");
 
+        var projectPath = VirtualProjectBuilder.GetVirtualProjectPath(programPath);
         new DotnetCommand(Log, "run-api")
             .WithStandardInput($$"""
                 {"$type":"GetProject","EntryPointFileFullPath":{{ToJson(programPath)}},"ArtifactsPath":"/artifacts"}
@@ -5622,8 +5651,10 @@ public void Api_Evaluation()
                       <PropertyGroup>
                         <IncludeProjectNameInArtifactsPaths>false</IncludeProjectNameInArtifactsPaths>
                         <ArtifactsPath>/artifacts</ArtifactsPath>
-                        <PublishDir>artifacts/$(MSBuildProjectName)</PublishDir>
-                        <PackageOutputPath>artifacts/$(MSBuildProjectName)</PackageOutputPath>
+                        <AssemblyName>A</AssemblyName>
+                        <RootNamespace>$(AssemblyName)</RootNamespace>
+                        <PublishDir>artifacts/$(AssemblyName)</PublishDir>
+                        <PackageOutputPath>artifacts/$(AssemblyName)</PackageOutputPath>
                         <FileBasedProgram>true</FileBasedProgram>
                         <FileBasedProgramsItemMapping>.cs=Compile;.resx=EmbeddedResource;.json=None;.razor=Content</FileBasedProgramsItemMapping>
                         <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
@@ -5667,7 +5698,7 @@ public void Api_Evaluation()
 
                     </Project>
 
-                    """)}},"Diagnostics":[]}
+                    """)}},"ProjectPath":{{ToJson(projectPath)}},"Diagnostics":[]}
                 """);
     }
 
@@ -5681,6 +5712,7 @@ public void Api_Diagnostic_01()
             #:property LangVersion=preview
             """);
 
+        var projectPath = VirtualProjectBuilder.GetVirtualProjectPath(programPath);
         new DotnetCommand(Log, "run-api")
             .WithStandardInput($$"""
                 {"$type":"GetProject","EntryPointFileFullPath":{{ToJson(programPath)}},"ArtifactsPath":"/artifacts"}
@@ -5694,8 +5726,10 @@ public void Api_Diagnostic_01()
                       <PropertyGroup>
                         <IncludeProjectNameInArtifactsPaths>false</IncludeProjectNameInArtifactsPaths>
                         <ArtifactsPath>/artifacts</ArtifactsPath>
-                        <PublishDir>artifacts/$(MSBuildProjectName)</PublishDir>
-                        <PackageOutputPath>artifacts/$(MSBuildProjectName)</PackageOutputPath>
+                        <AssemblyName>Program</AssemblyName>
+                        <RootNamespace>$(AssemblyName)</RootNamespace>
+                        <PublishDir>artifacts/$(AssemblyName)</PublishDir>
+                        <PackageOutputPath>artifacts/$(AssemblyName)</PackageOutputPath>
                         <FileBasedProgram>true</FileBasedProgram>
                         <FileBasedProgramsItemMapping>.cs=Compile;.resx=EmbeddedResource;.json=None;.razor=Content</FileBasedProgramsItemMapping>
                         <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
@@ -5734,7 +5768,7 @@ public void Api_Diagnostic_01()
 
                     </Project>
 
-                    """)}},"Diagnostics":
+                    """)}},"ProjectPath":{{ToJson(projectPath)}},"Diagnostics":
                 [{"Location":{
                 "Path":{{ToJson(programPath)}},
                 "Span":{"Start":{"Line":1,"Character":0},"End":{"Line":1,"Character":30}{{nop}}}{{nop}}},
@@ -5752,6 +5786,7 @@ public void Api_Diagnostic_02()
             Console.WriteLine();
             """);
 
+        var projectPath = VirtualProjectBuilder.GetVirtualProjectPath(programPath);
         new DotnetCommand(Log, "run-api")
             .WithStandardInput($$"""
                 {"$type":"GetProject","EntryPointFileFullPath":{{ToJson(programPath)}},"ArtifactsPath":"/artifacts"}
@@ -5765,8 +5800,10 @@ public void Api_Diagnostic_02()
                       <PropertyGroup>
                         <IncludeProjectNameInArtifactsPaths>false</IncludeProjectNameInArtifactsPaths>
                         <ArtifactsPath>/artifacts</ArtifactsPath>
-                        <PublishDir>artifacts/$(MSBuildProjectName)</PublishDir>
-                        <PackageOutputPath>artifacts/$(MSBuildProjectName)</PackageOutputPath>
+                        <AssemblyName>Program</AssemblyName>
+                        <RootNamespace>$(AssemblyName)</RootNamespace>
+                        <PublishDir>artifacts/$(AssemblyName)</PublishDir>
+                        <PackageOutputPath>artifacts/$(AssemblyName)</PackageOutputPath>
                         <FileBasedProgram>true</FileBasedProgram>
                         <FileBasedProgramsItemMapping>.cs=Compile;.resx=EmbeddedResource;.json=None;.razor=Content</FileBasedProgramsItemMapping>
                         <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
@@ -5805,7 +5842,7 @@ public void Api_Diagnostic_02()
 
                     </Project>
 
-                    """)}},"Diagnostics":
+                    """)}},"ProjectPath":{{ToJson(projectPath)}},"Diagnostics":
                 [{"Location":{
                 "Path":{{ToJson(programPath)}},
                 "Span":{"Start":{"Line":0,"Character":0},"End":{"Line":1,"Character":0}{{nop}}}{{nop}}},
@@ -6065,7 +6102,7 @@ public void MSBuildGet_Consistent(bool success, string subcommand, params string
         var projectBasedFiles = ReadFiles();
 
         fileBasedResult.StdOut.Should().Be(projectBasedResult.StdOut);
-        fileBasedResult.StdErr.Should().Be(projectBasedResult.StdErr);
+        fileBasedResult.StdErr?.Replace("Program.cs.csproj", "Program.csproj").Should().Be(projectBasedResult.StdErr);
         fileBasedResult.ExitCode.Should().Be(projectBasedResult.ExitCode).And.Be(success ? 0 : 1);
         fileBasedFiles.Should().Equal(projectBasedFiles);