Add assets to .csproj during win app init (#461)

fixes #444 

This pull request makes it so that all files in the Assets directory are
added as content items to the csproj during `winapp init`.

Uses a glob pattern `Assets/**` instead of individual references.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Nikola Metulev <nmetulev@users.noreply.github.com>

Author: 4 people

src/winapp-CLI/WinApp.Cli.Tests/DotNetServiceTests.cs

@@ -1062,4 +1062,88 @@ await File.WriteAllTextAsync(csprojPath, """
     }
 
     #endregion
+
+    #region EnsureAssetContentItemsAsync
+
+    [TestMethod]
+    public async Task EnsureAssetContentItems_AddsMissingAssetsGlob()
+    {
+        // Arrange
+        var csprojPath = Path.Combine(_testTempDirectory, "Test.csproj");
+        File.WriteAllText(csprojPath, @"<Project Sdk=""Microsoft.NET.Sdk"">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+  </PropertyGroup>
+</Project>
+");
+
+        // Act
+        var result = await _dotNetService.EnsureAssetContentItemsAsync(
+            new FileInfo(csprojPath), TestContext.CancellationToken);
+
+        // Assert
+        Assert.IsTrue(result, "Should modify csproj when no asset Content items exist");
+        var content = File.ReadAllText(csprojPath);
+        Assert.IsTrue(content.Contains(@"<Content Include=""Assets\**\*"" />"),
+            "Should add Assets glob Content item");
+        Assert.IsTrue(content.Contains("</Project>"),
+            "Should preserve </Project> closing tag");
+    }
+
+    [TestMethod]
+    public async Task EnsureAssetContentItems_SkipsWhenAlreadyPresent()
+    {
+        // Arrange
+        var csprojPath = Path.Combine(_testTempDirectory, "Test.csproj");
+        File.WriteAllText(csprojPath, @"<Project Sdk=""Microsoft.NET.Sdk"">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <Content Include=""Assets\**\*"" />
+  </ItemGroup>
+</Project>
+");
+
+        // Act
+        var result = await _dotNetService.EnsureAssetContentItemsAsync(
+            new FileInfo(csprojPath), TestContext.CancellationToken);
+
+        // Assert
+        Assert.IsFalse(result, "Should not modify csproj when asset Content items already exist");
+    }
+
+    [TestMethod]
+    public async Task EnsureAssetContentItems_SkipsWhenIndividualAssetPresent()
+    {
+        // Arrange
+        var csprojPath = Path.Combine(_testTempDirectory, "Test.csproj");
+        File.WriteAllText(csprojPath, @"<Project Sdk=""Microsoft.NET.Sdk"">
+  <ItemGroup>
+    <Content Include=""Assets\StoreLogo.png"" />
+  </ItemGroup>
+</Project>
+");
+
+        // Act
+        var result = await _dotNetService.EnsureAssetContentItemsAsync(
+            new FileInfo(csprojPath), TestContext.CancellationToken);
+
+        // Assert
+        Assert.IsFalse(result, "Should not modify csproj when individual asset Content items exist");
+    }
+
+    [TestMethod]
+    public async Task EnsureAssetContentItems_ReturnsFalseForMissingFile()
+    {
+        // Act
+        var result = await _dotNetService.EnsureAssetContentItemsAsync(
+            new FileInfo(Path.Combine(_testTempDirectory, "NonExistent.csproj")),
+            TestContext.CancellationToken);
+
+        // Assert
+        Assert.IsFalse(result);
+    }
+
+    #endregion
 }

src/winapp-CLI/WinApp.Cli.Tests/FakeDotNetService.cs

@@ -76,4 +76,7 @@ public Task<bool> RemoveWindowsPackageTypeNoneAsync(FileInfo csprojPath, Cancell
 
     public Task<bool> AnnotatePackageReferencesAsync(FileInfo csprojPath, IReadOnlyDictionary<string, string> packageComments, CancellationToken cancellationToken = default)
         => _real.AnnotatePackageReferencesAsync(csprojPath, packageComments, cancellationToken);
+
+    public Task<bool> EnsureAssetContentItemsAsync(FileInfo csprojPath, CancellationToken cancellationToken = default)
+        => _real.EnsureAssetContentItemsAsync(csprojPath, cancellationToken);
 }

src/winapp-CLI/WinApp.Cli/Services/DotNetService.cs

@@ -675,6 +675,41 @@ public async Task<bool> AnnotatePackageReferencesAsync(FileInfo csprojPath, IRea
 
         return modified;
     }
+
+    public async Task<bool> EnsureAssetContentItemsAsync(FileInfo csprojPath, CancellationToken cancellationToken = default)
+    {
+        if (!csprojPath.Exists)
+        {
+            return false;
+        }
+
+        var content = await File.ReadAllTextAsync(csprojPath.FullName, cancellationToken);
+
+        // Skip if the csproj already includes Assets content (glob or individual entries)
+        if (AssetsContentItemRegex().IsMatch(content))
+        {
+            return false;
+        }
+
+        // Insert a new ItemGroup with the Assets glob before </Project>
+        var closeProjectIdx = content.LastIndexOf("</Project>", StringComparison.OrdinalIgnoreCase);
+        if (closeProjectIdx < 0)
+        {
+            return false;
+        }
+
+        var itemGroup =
+            "  <ItemGroup>" + Environment.NewLine
+            + "    <Content Include=\"Assets\\**\\*\" />" + Environment.NewLine
+            + "  </ItemGroup>" + Environment.NewLine + Environment.NewLine;
+
+        content = content[..closeProjectIdx] + itemGroup + content[closeProjectIdx..];
+        await File.WriteAllTextAsync(csprojPath.FullName, content, cancellationToken);
+        return true;
+    }
+
+    [GeneratedRegex(@"<Content\s[^>]*Include\s*=\s*""Assets\\", RegexOptions.IgnoreCase)]
+    private static partial Regex AssetsContentItemRegex();
 }
 
 [JsonSerializable(typeof(DotNetPackageListJson))]

src/winapp-CLI/WinApp.Cli/Services/IDotNetService.cs

@@ -121,4 +121,14 @@ internal interface IDotNetService
     /// <param name="cancellationToken">Cancellation token.</param>
     /// <returns>True if any comments were added, false if all packages already had comments or were not found.</returns>
     Task<bool> AnnotatePackageReferencesAsync(FileInfo csprojPath, IReadOnlyDictionary<string, string> packageComments, CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Ensures the .csproj contains a <c>&lt;Content Include="Assets\**\*" /&gt;</c> item so that
+    /// generated visual assets (StoreLogo, AppList, etc.) are included in the MSIX package layout.
+    /// Without this, non-WinUI projects exclude the assets from the .build.appxrecipe.
+    /// </summary>
+    /// <param name="csprojPath">The project file to update.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>True if the .csproj was modified, false if it already had asset content items.</returns>
+    Task<bool> EnsureAssetContentItemsAsync(FileInfo csprojPath, CancellationToken cancellationToken = default);
 }

src/winapp-CLI/WinApp.Cli/Services/WorkspaceSetupService.cs

@@ -652,6 +652,15 @@ await taskContext.AddSubTaskAsync("Installing Windows App SDK Runtime", async (t
                     await SetupManifestSubTaskAsync(options, shouldGenerateManifest, manifestGenerationInfo, taskContext, cancellationToken);
                 }
 
+                // Add generated assets as Content items so MSIX tooling includes them in the package layout
+                if (isDotNetProject && csprojFile != null && shouldGenerateManifest)
+                {
+                    if (await dotNetService.EnsureAssetContentItemsAsync(csprojFile, cancellationToken))
+                    {
+                        taskContext.AddDebugMessage($"{UiSymbols.Check} Added asset Content items to .csproj");
+                    }
+                }
+
                 // Save configuration (native/C++ projects only — .NET uses .csproj PackageReferences)
                 if (!isDotNetProject && !options.RequireExistingConfig && options.SdkInstallMode != SdkInstallMode.None && usedVersions != null)
                 {