Add tree context menu, missing connection settings, and fix lazy-load browse

Right-click on browse tree nodes to Subscribe (multi-select) or View History
(Variable nodes only), with automatic tab switching. Add missing UI controls
for failover URLs, session timeout, auto-accept certificates, and certificate
store path. Fix tree expansion by adding two-way IsExpanded binding on
TreeViewItem.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/ViewModels/MainWindowViewModel.cs

@@ -1,3 +1,4 @@
+using System.Collections.ObjectModel;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using ZB.MOM.WW.LmxOpcUa.Client.Shared;
@@ -26,6 +27,20 @@ public partial class MainWindowViewModel : ObservableObject
     [ObservableProperty]
     private SecurityMode _selectedSecurityMode = SecurityMode.None;
 
+    [ObservableProperty]
+    private string? _failoverUrls;
+
+    [ObservableProperty]
+    private int _sessionTimeoutSeconds = 60;
+
+    [ObservableProperty]
+    private bool _autoAcceptCertificates = true;
+
+    [ObservableProperty]
+    private string _certificateStorePath = Path.Combine(
+        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+        "LmxOpcUaClient", "pki");
+
     /// <summary>All available security modes.</summary>
     public IReadOnlyList<SecurityMode> SecurityModes { get; } = Enum.GetValues<SecurityMode>();
 
@@ -51,6 +66,15 @@ public partial class MainWindowViewModel : ObservableObject
     [ObservableProperty]
     private int _subscriptionCount;
 
+    [ObservableProperty]
+    private int _selectedTabIndex;
+
+    [ObservableProperty]
+    private bool _isHistoryEnabledForSelection;
+
+    /// <summary>The currently selected tree nodes (supports multi-select).</summary>
+    public ObservableCollection<TreeNodeViewModel> SelectedTreeNodes { get; } = new();
+
     public BrowseTreeViewModel BrowseTree { get; }
     public ReadWriteViewModel ReadWrite { get; }
     public SubscriptionsViewModel Subscriptions { get; }
@@ -135,7 +159,11 @@ public partial class MainWindowViewModel : ObservableObject
                 EndpointUrl = EndpointUrl,
                 Username = Username,
                 Password = Password,
-                SecurityMode = SelectedSecurityMode
+                SecurityMode = SelectedSecurityMode,
+                FailoverUrls = ParseFailoverUrls(FailoverUrls),
+                SessionTimeoutSeconds = SessionTimeoutSeconds,
+                AutoAcceptCertificates = AutoAcceptCertificates,
+                CertificateStorePath = CertificateStorePath
             };
             settings.Validate();
 
@@ -195,4 +223,56 @@ public partial class MainWindowViewModel : ObservableObject
             });
         }
     }
+
+    /// <summary>
+    /// Subscribes all selected tree nodes and switches to the Subscriptions tab.
+    /// </summary>
+    [RelayCommand]
+    private async Task SubscribeSelectedNodesAsync()
+    {
+        if (SelectedTreeNodes.Count == 0 || !IsConnected) return;
+
+        var nodes = SelectedTreeNodes.ToList();
+        foreach (var node in nodes)
+        {
+            await Subscriptions.AddSubscriptionForNodeAsync(node.NodeId);
+        }
+
+        SubscriptionCount = Subscriptions.SubscriptionCount;
+        SelectedTabIndex = 1; // Subscriptions tab
+    }
+
+    /// <summary>
+    /// Sets the history tab's selected node and switches to the History tab.
+    /// </summary>
+    [RelayCommand]
+    private void ViewHistoryForSelectedNode()
+    {
+        if (SelectedTreeNodes.Count == 0 || !IsConnected) return;
+
+        var node = SelectedTreeNodes[0];
+        History.SelectedNodeId = node.NodeId;
+        SelectedTabIndex = 3; // History tab
+    }
+
+    /// <summary>
+    /// Updates whether "View History" should be enabled based on the selected node's type.
+    /// Only Variable nodes can have history.
+    /// </summary>
+    public void UpdateHistoryEnabledForSelection()
+    {
+        IsHistoryEnabledForSelection = IsConnected
+            && SelectedTreeNodes.Count > 0
+            && SelectedTreeNodes[0].NodeClass == "Variable";
+    }
+
+    private static string[]? ParseFailoverUrls(string? csv)
+    {
+        if (string.IsNullOrWhiteSpace(csv))
+            return null;
+
+        return csv.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
+                  .Where(u => !string.IsNullOrEmpty(u))
+                  .ToArray();
+    }
 }

src/ZB.MOM.WW.LmxOpcUa.Client.UI/ViewModels/SubscriptionsViewModel.cs

@@ -114,6 +114,33 @@ public partial class SubscriptionsViewModel : ObservableObject
         }
     }
 
+    /// <summary>
+    /// Subscribes to a node by ID (used by context menu). Skips if already subscribed.
+    /// </summary>
+    public async Task AddSubscriptionForNodeAsync(string nodeIdStr, int intervalMs = 1000)
+    {
+        if (!IsConnected || string.IsNullOrWhiteSpace(nodeIdStr)) return;
+
+        // Skip if already subscribed
+        if (ActiveSubscriptions.Any(s => s.NodeId == nodeIdStr)) return;
+
+        try
+        {
+            var nodeId = NodeId.Parse(nodeIdStr);
+            await _service.SubscribeAsync(nodeId, intervalMs);
+
+            _dispatcher.Post(() =>
+            {
+                ActiveSubscriptions.Add(new SubscriptionItemViewModel(nodeIdStr, intervalMs));
+                SubscriptionCount = ActiveSubscriptions.Count;
+            });
+        }
+        catch
+        {
+            // Subscription failed
+        }
+    }
+
     /// <summary>
     /// Clears all subscriptions and resets state.
     /// </summary>