diff --git a/NEW/src/Utils/JdeScoping.ConfigManager/ViewModels/MainWindowViewModel.cs b/NEW/src/Utils/JdeScoping.ConfigManager/ViewModels/MainWindowViewModel.cs
index 8365dba..0c941a8 100644
--- a/NEW/src/Utils/JdeScoping.ConfigManager/ViewModels/MainWindowViewModel.cs
+++ b/NEW/src/Utils/JdeScoping.ConfigManager/ViewModels/MainWindowViewModel.cs
@@ -3,6 +3,7 @@ using System.Windows.Input;
 using Avalonia.Media;
 using JdeScoping.ConfigManager.Models;
 using JdeScoping.ConfigManager.Services;
+using JdeScoping.ConfigManager.ViewModels.Forms;
 using Microsoft.Extensions.Logging;
 
 namespace JdeScoping.ConfigManager.ViewModels;
@@ -12,10 +13,12 @@ namespace JdeScoping.ConfigManager.ViewModels;
 /// </summary>
 public class MainWindowViewModel : ViewModelBase
 {
+    private readonly IFileSystem _fileSystem;
     private readonly IConfigFileService _configFileService;
     private readonly IValidationService _validationService;
     private readonly IBackupService _backupService;
     private readonly IAutoDiscoveryService _autoDiscoveryService;
+    private readonly IDialogService? _dialogService;
     private readonly ILogger<MainWindowViewModel>? _logger;
 
     private string _configFolderPath = "No folder selected";
@@ -28,30 +31,45 @@ public class MainWindowViewModel : ViewModelBase
     private ConfigModel? _appSettings;
     private PipelinesConfigModel? _pipelines;
 
+    /// <summary>
+    /// Gets or sets the currently loaded configuration folder path.
+    /// </summary>
     public string ConfigFolderPath
     {
         get => _configFolderPath;
         set => SetProperty(ref _configFolderPath, value);
     }
 
+    /// <summary>
+    /// Gets or sets a value indicating whether there are unsaved configuration changes.
+    /// </summary>
     public bool HasUnsavedChanges
     {
         get => _hasUnsavedChanges;
         set => SetProperty(ref _hasUnsavedChanges, value);
     }
 
+    /// <summary>
+    /// Gets or sets the validation status message displayed to the user.
+    /// </summary>
     public string ValidationStatus
     {
         get => _validationStatus;
         set => SetProperty(ref _validationStatus, value);
     }
 
+    /// <summary>
+    /// Gets or sets the brush color for the validation status indicator.
+    /// </summary>
     public IBrush ValidationStatusColor
     {
         get => _validationStatusColor;
         set => SetProperty(ref _validationStatusColor, value);
     }
 
+    /// <summary>
+    /// Gets or sets the currently selected tree node in the configuration tree view.
+    /// </summary>
     public TreeNodeViewModel? SelectedNode
     {
         get => _selectedNode;
@@ -62,33 +80,80 @@ public class MainWindowViewModel : ViewModelBase
         }
     }
 
+    /// <summary>
+    /// Gets or sets the view model for the form displayed when a node is selected.
+    /// </summary>
     public object? SelectedFormViewModel
     {
         get => _selectedFormViewModel;
         set => SetProperty(ref _selectedFormViewModel, value);
     }
 
+    /// <summary>
+    /// Gets the collection of tree nodes representing the configuration structure.
+    /// </summary>
     public ObservableCollection<TreeNodeViewModel> TreeNodes { get; } = [];
 
+    /// <summary>
+    /// Gets the command for opening a configuration folder.
+    /// </summary>
     public ICommand OpenFolderCommand { get; }
+
+    /// <summary>
+    /// Gets the command for saving configuration changes.
+    /// </summary>
     public ICommand SaveCommand { get; }
+
+    /// <summary>
+    /// Gets the command for exiting the application.
+    /// </summary>
     public ICommand ExitCommand { get; }
+
+    /// <summary>
+    /// Gets the command for undoing the last configuration change.
+    /// </summary>
     public ICommand UndoCommand { get; }
+
+    /// <summary>
+    /// Gets the command for redoing the last undone configuration change.
+    /// </summary>
     public ICommand RedoCommand { get; }
+
+    /// <summary>
+    /// Gets the command for validating the current configuration.
+    /// </summary>
     public ICommand ValidateCommand { get; }
+
+    /// <summary>
+    /// Gets the command for testing database connections.
+    /// </summary>
     public ICommand TestConnectionCommand { get; }
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MainWindowViewModel"/> class.
+    /// </summary>
+    /// <param name="fileSystem">File system abstraction for I/O operations.</param>
+    /// <param name="configFileService">Service for loading and saving configuration files.</param>
+    /// <param name="validationService">Service for validating configuration settings.</param>
+    /// <param name="backupService">Service for creating configuration backups.</param>
+    /// <param name="autoDiscoveryService">Service for discovering configuration folder locations.</param>
+    /// <param name="dialogService">Service for showing platform dialogs.</param>
+    /// <param name="logger">Optional logger for recording view model activities.</param>
     public MainWindowViewModel(
+        IFileSystem fileSystem,
         IConfigFileService configFileService,
         IValidationService validationService,
         IBackupService backupService,
         IAutoDiscoveryService autoDiscoveryService,
+        IDialogService? dialogService,
         ILogger<MainWindowViewModel>? logger)
     {
+        _fileSystem = fileSystem;
         _configFileService = configFileService;
         _validationService = validationService;
         _backupService = backupService;
         _autoDiscoveryService = autoDiscoveryService;
+        _dialogService = dialogService;
         _logger = logger;
 
         OpenFolderCommand = new AsyncRelayCommand(OpenFolderAsync);
@@ -106,10 +171,12 @@ public class MainWindowViewModel : ViewModelBase
     /// Design-time constructor for XAML previewer.
     /// </summary>
     public MainWindowViewModel() : this(
+        new FileSystem(),
         new ConfigFileService(new FileSystem()),
         new ValidationService(),
         new BackupService(new FileSystem()),
         new AutoDiscoveryService(new FileSystem()),
+        null,
         null)
     {
     }
@@ -131,9 +198,17 @@ public class MainWindowViewModel : ViewModelBase
     /// </summary>
     private async Task OpenFolderAsync()
     {
-        // TODO: Show folder picker dialog
-        _logger?.LogInformation("Open folder requested");
-        await Task.CompletedTask;
+        if (_dialogService == null)
+        {
+            _logger?.LogWarning("Dialog service is not available");
+            return;
+        }
+
+        var folder = await _dialogService.ShowFolderPickerAsync("Select Configuration Folder");
+        if (folder != null)
+        {
+            await LoadConfigAsync(folder);
+        }
     }
 
     /// <summary>
@@ -201,8 +276,48 @@ public class MainWindowViewModel : ViewModelBase
     /// </summary>
     private void OnSelectedNodeChanged()
     {
-        // TODO: Load appropriate form ViewModel based on selected node
-        SelectedFormViewModel = null;
+        if (_selectedNode == null || _appSettings == null)
+        {
+            SelectedFormViewModel = null;
+            return;
+        }
+
+        SelectedFormViewModel = _selectedNode.SectionKey switch
+        {
+            "DataSync" => new DataSyncFormViewModel(_appSettings.DataSync, MarkAsChanged),
+            "DataAccess" => new DataAccessFormViewModel(_appSettings.DataAccess, MarkAsChanged),
+            "Auth" => new AuthFormViewModel(_appSettings.Auth, MarkAsChanged),
+            "Ldap" => new LdapFormViewModel(_appSettings.Ldap, MarkAsChanged),
+            "Search" => new SearchFormViewModel(_appSettings.Search, MarkAsChanged),
+            "ExcelExport" => new ExcelExportFormViewModel(_appSettings.ExcelExport, MarkAsChanged),
+            _ when _selectedNode.NodeType == TreeNodeType.Pipeline && _pipelines != null
+                => _pipelines.Pipelines.TryGetValue(_selectedNode.SectionKey!, out var pipeline)
+                    ? new PipelineFormViewModel(_selectedNode.SectionKey!, pipeline, MarkAsChanged)
+                    : null,
+            _ => null
+        };
+    }
+
+    /// <summary>
+    /// Marks the configuration as having unsaved changes.
+    /// </summary>
+    private void MarkAsChanged()
+    {
+        HasUnsavedChanges = true;
+        if (_selectedNode != null)
+            _selectedNode.IsModified = true;
+    }
+
+    /// <summary>
+    /// Loads configuration for testing purposes.
+    /// </summary>
+    /// <param name="appSettings">The application settings configuration model.</param>
+    /// <param name="pipelines">The pipelines configuration model.</param>
+    public void LoadConfigForTesting(ConfigModel? appSettings, PipelinesConfigModel? pipelines)
+    {
+        _appSettings = appSettings;
+        _pipelines = pipelines;
+        BuildTreeNodes();
     }
 
     /// <summary>
diff --git a/NEW/tests/JdeScoping.ConfigManager.Tests/ViewModels/MainWindowViewModelTests.cs b/NEW/tests/JdeScoping.ConfigManager.Tests/ViewModels/MainWindowViewModelTests.cs
new file mode 100644
index 0000000..7afc6c0
--- /dev/null
+++ b/NEW/tests/JdeScoping.ConfigManager.Tests/ViewModels/MainWindowViewModelTests.cs
@@ -0,0 +1,316 @@
+using JdeScoping.ConfigManager.Models;
+using JdeScoping.ConfigManager.Services;
+using JdeScoping.ConfigManager.ViewModels;
+using JdeScoping.ConfigManager.ViewModels.Forms;
+using Microsoft.Extensions.Logging;
+using NSubstitute;
+
+namespace JdeScoping.ConfigManager.Tests.ViewModels;
+
+public class MainWindowViewModelTests
+{
+    private readonly IFileSystem _fileSystem;
+    private readonly IConfigFileService _configFileService;
+    private readonly IValidationService _validationService;
+    private readonly IBackupService _backupService;
+    private readonly IAutoDiscoveryService _autoDiscoveryService;
+    private readonly IDialogService _dialogService;
+    private readonly ILogger<MainWindowViewModel> _logger;
+
+    public MainWindowViewModelTests()
+    {
+        _fileSystem = Substitute.For<IFileSystem>();
+        _configFileService = Substitute.For<IConfigFileService>();
+        _validationService = Substitute.For<IValidationService>();
+        _backupService = Substitute.For<IBackupService>();
+        _autoDiscoveryService = Substitute.For<IAutoDiscoveryService>();
+        _dialogService = Substitute.For<IDialogService>();
+        _logger = Substitute.For<ILogger<MainWindowViewModel>>();
+
+        _validationService.ValidateAppSettings(Arg.Any<ConfigModel>())
+            .Returns(new ValidationResult());
+        _validationService.ValidatePipelines(Arg.Any<PipelinesConfigModel>())
+            .Returns(new ValidationResult());
+    }
+
+    [Fact]
+    public void SelectingDataSyncNode_LoadsDataSyncFormViewModel()
+    {
+        // Arrange
+        var config = new ConfigModel { DataSync = new DataSyncSection { MaxDegreeOfParallelism = 8 } };
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var dataSyncNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "DataSync");
+
+        // Act
+        sut.SelectedNode = dataSyncNode;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeOfType<DataSyncFormViewModel>();
+        ((DataSyncFormViewModel)sut.SelectedFormViewModel!).MaxDegreeOfParallelism.ShouldBe(8);
+    }
+
+    [Fact]
+    public void SelectingDataAccessNode_LoadsDataAccessFormViewModel()
+    {
+        // Arrange
+        var config = new ConfigModel { DataAccess = new DataAccessSection { ProductionSchema = "custom" } };
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var dataAccessNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "DataAccess");
+
+        // Act
+        sut.SelectedNode = dataAccessNode;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeOfType<DataAccessFormViewModel>();
+        ((DataAccessFormViewModel)sut.SelectedFormViewModel!).ProductionSchema.ShouldBe("custom");
+    }
+
+    [Fact]
+    public void SelectingAuthNode_LoadsAuthFormViewModel()
+    {
+        // Arrange
+        var config = new ConfigModel { Auth = new AuthSection { CookieName = "TestCookie" } };
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var authNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "Auth");
+
+        // Act
+        sut.SelectedNode = authNode;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeOfType<AuthFormViewModel>();
+        ((AuthFormViewModel)sut.SelectedFormViewModel!).CookieName.ShouldBe("TestCookie");
+    }
+
+    [Fact]
+    public void SelectingLdapNode_LoadsLdapFormViewModel()
+    {
+        // Arrange
+        var config = new ConfigModel { Ldap = new LdapSection { GroupDn = "CN=TestGroup" } };
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var ldapNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "Ldap");
+
+        // Act
+        sut.SelectedNode = ldapNode;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeOfType<LdapFormViewModel>();
+        ((LdapFormViewModel)sut.SelectedFormViewModel!).GroupDn.ShouldBe("CN=TestGroup");
+    }
+
+    [Fact]
+    public void SelectingSearchNode_LoadsSearchFormViewModel()
+    {
+        // Arrange
+        var config = new ConfigModel { Search = new SearchSection { MaxResultRows = 50000 } };
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var searchNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "Search");
+
+        // Act
+        sut.SelectedNode = searchNode;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeOfType<SearchFormViewModel>();
+        ((SearchFormViewModel)sut.SelectedFormViewModel!).MaxResultRows.ShouldBe(50000);
+    }
+
+    [Fact]
+    public void SelectingExcelExportNode_LoadsExcelExportFormViewModel()
+    {
+        // Arrange
+        var config = new ConfigModel { ExcelExport = new ExcelExportSection { TimezoneId = "America/New_York" } };
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var excelNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "ExcelExport");
+
+        // Act
+        sut.SelectedNode = excelNode;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeOfType<ExcelExportFormViewModel>();
+        ((ExcelExportFormViewModel)sut.SelectedFormViewModel!).TimezoneId.ShouldBe("America/New_York");
+    }
+
+    [Fact]
+    public void SelectingPipelineNode_LoadsPipelineFormViewModel()
+    {
+        // Arrange
+        var config = new ConfigModel();
+        var pipelines = new PipelinesConfigModel
+        {
+            Pipelines = new Dictionary<string, PipelineModel>
+            {
+                ["WorkOrders"] = new PipelineModel
+                {
+                    Source = new PipelineSource { Connection = "jde", Query = "SELECT * FROM WO" },
+                    Destination = new PipelineDestination { Table = "WorkOrder_Curr" }
+                }
+            }
+        };
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, pipelines);
+
+        var pipelineNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "WorkOrders");
+
+        // Act
+        sut.SelectedNode = pipelineNode;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeOfType<PipelineFormViewModel>();
+        var pipelineForm = (PipelineFormViewModel)sut.SelectedFormViewModel!;
+        pipelineForm.Name.ShouldBe("WorkOrders");
+        pipelineForm.Connection.ShouldBe("jde");
+    }
+
+    [Fact]
+    public void ModifyingFormProperty_SetsHasUnsavedChanges()
+    {
+        // Arrange
+        var config = new ConfigModel();
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var dataSyncNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "DataSync");
+        sut.SelectedNode = dataSyncNode;
+
+        // Act
+        ((DataSyncFormViewModel)sut.SelectedFormViewModel!).BatchSize = 10000;
+
+        // Assert
+        sut.HasUnsavedChanges.ShouldBeTrue();
+    }
+
+    [Fact]
+    public void ModifyingFormProperty_MarksNodeAsModified()
+    {
+        // Arrange
+        var config = new ConfigModel();
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var dataSyncNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "DataSync");
+        sut.SelectedNode = dataSyncNode;
+
+        // Act
+        ((DataSyncFormViewModel)sut.SelectedFormViewModel!).MaxDegreeOfParallelism = 16;
+
+        // Assert
+        dataSyncNode.IsModified.ShouldBeTrue();
+    }
+
+    [Fact]
+    public void SelectingFolderNode_SetsSelectedFormViewModelToNull()
+    {
+        // Arrange
+        var config = new ConfigModel();
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var folderNode = sut.TreeNodes.First(); // Settings folder
+
+        // Act
+        sut.SelectedNode = folderNode;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeNull();
+    }
+
+    [Fact]
+    public void SelectingNull_SetsSelectedFormViewModelToNull()
+    {
+        // Arrange
+        var config = new ConfigModel();
+        var sut = CreateViewModel();
+        sut.LoadConfigForTesting(config, null);
+
+        var dataSyncNode = sut.TreeNodes
+            .SelectMany(n => n.Children)
+            .First(n => n.SectionKey == "DataSync");
+        sut.SelectedNode = dataSyncNode;
+
+        // Act
+        sut.SelectedNode = null;
+
+        // Assert
+        sut.SelectedFormViewModel.ShouldBeNull();
+    }
+
+    [Fact]
+    public void LoadConfigForTesting_BuildsTreeNodes()
+    {
+        // Arrange
+        var config = new ConfigModel();
+        var sut = CreateViewModel();
+
+        // Act
+        sut.LoadConfigForTesting(config, null);
+
+        // Assert
+        sut.TreeNodes.Count.ShouldBe(2); // Settings and Pipelines folders
+        sut.TreeNodes[0].Name.ShouldBe("Settings");
+        sut.TreeNodes[0].Children.Count.ShouldBe(6); // DataSync, DataAccess, Auth, Ldap, Search, ExcelExport
+    }
+
+    [Fact]
+    public void LoadConfigForTesting_WithPipelines_BuildsPipelineNodes()
+    {
+        // Arrange
+        var config = new ConfigModel();
+        var pipelines = new PipelinesConfigModel
+        {
+            Pipelines = new Dictionary<string, PipelineModel>
+            {
+                ["Pipeline1"] = new PipelineModel(),
+                ["Pipeline2"] = new PipelineModel()
+            }
+        };
+        var sut = CreateViewModel();
+
+        // Act
+        sut.LoadConfigForTesting(config, pipelines);
+
+        // Assert
+        sut.TreeNodes[1].Name.ShouldBe("Pipelines");
+        sut.TreeNodes[1].Children.Count.ShouldBe(2);
+    }
+
+    private MainWindowViewModel CreateViewModel()
+    {
+        return new MainWindowViewModel(
+            _fileSystem,
+            _configFileService,
+            _validationService,
+            _backupService,
+            _autoDiscoveryService,
+            _dialogService,
+            _logger);
+    }
+}