Add UI features, alarm ack, historian UTC fix, and Client.UI documentation

Major changes across the client stack:
- Settings persistence (connection, subscriptions, alarm source)
- Deferred OPC UA SDK init for instant startup
- Array/status code formatting, write value popup, alarm acknowledgment
- Severity-colored alarm rows, condition dedup on server side
- DateTimeRangePicker control with preset buttons and UTC text input
- Historian queries use wwTimezone=UTC and OPCQuality column
- Recursive subscribe from tree, multi-select remove
- Connection panel with expander, folder chooser for cert path
- Dynamic tab headers showing subscription/alarm counts
- Client.UI.md documentation with headless-rendered screenshots

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

src/ZB.MOM.WW.LmxOpcUa.Client.Shared/Adapters/DefaultSessionAdapter.cs

@@ -220,4 +220,27 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
 
         _session.Dispose();
     }
+
+    public async Task<IList<object>?> CallMethodAsync(NodeId objectId, NodeId methodId, object[] inputArguments,
+        CancellationToken ct = default)
+    {
+        var result = await _session.CallAsync(
+            null,
+            new CallMethodRequestCollection
+            {
+                new()
+                {
+                    ObjectId = objectId,
+                    MethodId = methodId,
+                    InputArguments = new VariantCollection(inputArguments.Select(a => new Variant(a)))
+                }
+            },
+            ct);
+
+        var callResult = result.Results[0];
+        if (StatusCode.IsBad(callResult.StatusCode))
+            throw new ServiceResultException(callResult.StatusCode);
+
+        return callResult.OutputArguments?.Select(v => v.Value).ToList();
+    }
 }

src/ZB.MOM.WW.LmxOpcUa.Client.Shared/Adapters/ISessionAdapter.cs

@@ -59,5 +59,7 @@ internal interface ISessionAdapter : IDisposable
     /// </summary>
     Task<ISubscriptionAdapter> CreateSubscriptionAsync(int publishingIntervalMs, CancellationToken ct = default);
 
+    Task<IList<object>?> CallMethodAsync(NodeId objectId, NodeId methodId, object[] inputArguments, CancellationToken ct = default);
+
     Task CloseAsync(CancellationToken ct = default);
 }

src/ZB.MOM.WW.LmxOpcUa.Client.Shared/IOpcUaClientService.cs

@@ -25,6 +25,7 @@ public interface IOpcUaClientService : IDisposable
     Task SubscribeAlarmsAsync(NodeId? sourceNodeId = null, int intervalMs = 1000, CancellationToken ct = default);
     Task UnsubscribeAlarmsAsync(CancellationToken ct = default);
     Task RequestConditionRefreshAsync(CancellationToken ct = default);
+    Task<StatusCode> AcknowledgeAlarmAsync(string conditionNodeId, byte[] eventId, string comment, CancellationToken ct = default);
 
     Task<IReadOnlyList<DataValue>> HistoryReadRawAsync(NodeId nodeId, DateTime startTime, DateTime endTime,
         int maxValues = 1000, CancellationToken ct = default);

src/ZB.MOM.WW.LmxOpcUa.Client.Shared/Models/AlarmEventArgs.cs

@@ -13,7 +13,9 @@ public sealed class AlarmEventArgs : EventArgs
         bool retain,
         bool activeState,
         bool ackedState,
-        DateTime time)
+        DateTime time,
+        byte[]? eventId = null,
+        string? conditionNodeId = null)
     {
         SourceName = sourceName;
         ConditionName = conditionName;
@@ -23,6 +25,8 @@ public sealed class AlarmEventArgs : EventArgs
         ActiveState = activeState;
         AckedState = ackedState;
         Time = time;
+        EventId = eventId;
+        ConditionNodeId = conditionNodeId;
     }
 
     /// <summary>The name of the source object that raised the alarm.</summary>
@@ -48,4 +52,10 @@ public sealed class AlarmEventArgs : EventArgs
 
     /// <summary>The time the event occurred.</summary>
     public DateTime Time { get; }
+
+    /// <summary>The EventId used for alarm acknowledgment.</summary>
+    public byte[]? EventId { get; }
+
+    /// <summary>The NodeId of the condition instance (SourceNode), used for acknowledgment.</summary>
+    public string? ConditionNodeId { get; }
 }

src/ZB.MOM.WW.LmxOpcUa.Client.Shared/OpcUaClientService.cs

@@ -277,6 +277,28 @@ public sealed class OpcUaClientService : IOpcUaClientService
         Logger.Debug("Condition refresh requested");
     }
 
+    public async Task<StatusCode> AcknowledgeAlarmAsync(string conditionNodeId, byte[] eventId, string comment,
+        CancellationToken ct = default)
+    {
+        ThrowIfDisposed();
+        ThrowIfNotConnected();
+
+        // The Acknowledge method lives on the .Condition child node, not the source node itself
+        var conditionObjId = conditionNodeId.EndsWith(".Condition")
+            ? NodeId.Parse(conditionNodeId)
+            : NodeId.Parse(conditionNodeId + ".Condition");
+        var acknowledgeMethodId = MethodIds.AcknowledgeableConditionType_Acknowledge;
+
+        await _session!.CallMethodAsync(
+            conditionObjId,
+            acknowledgeMethodId,
+            [eventId, new LocalizedText(comment)],
+            ct);
+
+        Logger.Debug("Acknowledged alarm on {ConditionId}", conditionNodeId);
+        return StatusCodes.Good;
+    }
+
     public async Task<IReadOnlyList<DataValue>> HistoryReadRawAsync(
         NodeId nodeId, DateTime startTime, DateTime endTime, int maxValues = 1000, CancellationToken ct = default)
     {
@@ -502,17 +524,86 @@ public sealed class OpcUaClientService : IOpcUaClientService
         if (fields == null || fields.Count < 6)
             return;
 
+        var eventId = fields.Count > 0 ? fields[0].Value as byte[] : null;
         var sourceName = fields.Count > 2 ? fields[2].Value as string ?? string.Empty : string.Empty;
-        var time = fields.Count > 3 ? fields[3].Value as DateTime? ?? DateTime.MinValue : DateTime.MinValue;
+        var time = DateTime.MinValue;
+        if (fields.Count > 3 && fields[3].Value != null)
+        {
+            if (fields[3].Value is DateTime dt)
+                time = dt;
+            else if (DateTime.TryParse(fields[3].Value.ToString(), out var parsed))
+                time = parsed;
+        }
         var message = fields.Count > 4 ? (fields[4].Value as LocalizedText)?.Text ?? string.Empty : string.Empty;
         var severity = fields.Count > 5 ? Convert.ToUInt16(fields[5].Value) : (ushort)0;
         var conditionName = fields.Count > 6 ? fields[6].Value as string ?? string.Empty : string.Empty;
-        var retain = fields.Count > 7 ? fields[7].Value as bool? ?? false : false;
-        var ackedState = fields.Count > 8 ? fields[8].Value as bool? ?? false : false;
-        var activeState = fields.Count > 9 ? fields[9].Value as bool? ?? false : false;
+        var retain = fields.Count > 7 && ParseBool(fields[7].Value);
+        var conditionNodeId = fields.Count > 12 ? fields[12].Value?.ToString() : null;
+
+        // Try standard OPC UA ActiveState/AckedState fields first
+        bool? ackedField = fields.Count > 8 && fields[8].Value != null ? ParseBool(fields[8].Value) : null;
+        bool? activeField = fields.Count > 9 && fields[9].Value != null ? ParseBool(fields[9].Value) : null;
+
+        var ackedState = ackedField ?? false;
+        var activeState = activeField ?? false;
+
+        // Fallback: read InAlarm/Acked from condition node Galaxy attributes
+        // when the server doesn't populate standard event fields.
+        // Must run on a background thread to avoid deadlocking the notification thread.
+        if (ackedField == null && activeField == null && conditionNodeId != null && _session != null)
+        {
+            var session = _session;
+            var capturedConditionNodeId = conditionNodeId;
+            var capturedMessage = message;
+            _ = Task.Run(async () =>
+            {
+                try
+                {
+                    var inAlarmValue = await session.ReadValueAsync(NodeId.Parse($"{capturedConditionNodeId}.InAlarm"));
+                    if (inAlarmValue.Value is bool inAlarm) activeState = inAlarm;
+
+                    var ackedValue = await session.ReadValueAsync(NodeId.Parse($"{capturedConditionNodeId}.Acked"));
+                    if (ackedValue.Value is bool acked) ackedState = acked;
+
+                    if (time == DateTime.MinValue && activeState)
+                    {
+                        var timeValue = await session.ReadValueAsync(NodeId.Parse($"{capturedConditionNodeId}.TimeAlarmOn"));
+                        if (timeValue.Value is DateTime alarmTime && alarmTime != DateTime.MinValue)
+                            time = alarmTime;
+                    }
+
+                    // Read alarm description to use as message
+                    try
+                    {
+                        var descValue = await session.ReadValueAsync(NodeId.Parse($"{capturedConditionNodeId}.DescAttrName"));
+                        if (descValue.Value is string desc && !string.IsNullOrEmpty(desc))
+                            capturedMessage = desc;
+                    }
+                    catch { /* DescAttrName may not exist */ }
+                }
+                catch
+                {
+                    // Supplemental read failed; use defaults
+                }
+
+                AlarmEvent?.Invoke(this, new AlarmEventArgs(
+                    sourceName, conditionName, severity, capturedMessage, retain, activeState, ackedState, time,
+                    eventId, capturedConditionNodeId));
+            });
+            return;
+        }
 
         AlarmEvent?.Invoke(this, new AlarmEventArgs(
-            sourceName, conditionName, severity, message, retain, activeState, ackedState, time));
+            sourceName, conditionName, severity, message, retain, activeState, ackedState, time,
+            eventId, conditionNodeId));
+    }
+
+    private static bool ParseBool(object? value)
+    {
+        if (value == null) return false;
+        if (value is bool b) return b;
+        try { return Convert.ToBoolean(value); }
+        catch { return false; }
     }
 
     private static EventFilter CreateAlarmEventFilter()
@@ -542,6 +633,8 @@ public sealed class OpcUaClientService : IOpcUaClientService
         filter.AddSelectClause(ObjectTypeIds.AlarmConditionType, "EnabledState/Id");
         // 11: SuppressedOrShelved
         filter.AddSelectClause(ObjectTypeIds.AlarmConditionType, "SuppressedOrShelved");
+        // 12: SourceNode (ConditionId for acknowledgment)
+        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.SourceNode);
         return filter;
     }
 

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Assets/app-icon.svg

@@ -0,0 +1,18 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" width="64" height="64">
+  <!-- Server/network icon for OPC UA -->
+  <rect x="8" y="6" width="48" height="36" rx="4" fill="#2563eb" stroke="#1d4ed8" stroke-width="2"/>
+  <rect x="14" y="12" width="36" height="24" rx="2" fill="#dbeafe"/>
+  <!-- Network nodes -->
+  <circle cx="24" cy="24" r="4" fill="#2563eb"/>
+  <circle cx="40" cy="20" r="3" fill="#3b82f6"/>
+  <circle cx="36" cy="30" r="3" fill="#3b82f6"/>
+  <!-- Connection lines -->
+  <line x1="24" y1="24" x2="40" y2="20" stroke="#60a5fa" stroke-width="1.5"/>
+  <line x1="24" y1="24" x2="36" y2="30" stroke="#60a5fa" stroke-width="1.5"/>
+  <line x1="40" y1="20" x2="36" y2="30" stroke="#60a5fa" stroke-width="1.5"/>
+  <!-- Base stand -->
+  <rect x="24" y="42" width="16" height="4" rx="1" fill="#6b7280"/>
+  <rect x="20" y="46" width="24" height="4" rx="2" fill="#9ca3af"/>
+  <!-- UA text -->
+  <text x="32" y="60" text-anchor="middle" font-family="Arial,sans-serif" font-size="8" font-weight="bold" fill="#1d4ed8">UA</text>
+</svg>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Controls/DateTimePicker.axaml

@@ -0,0 +1,11 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="ZB.MOM.WW.LmxOpcUa.Client.UI.Controls.DateTimePicker">
+    <StackPanel Orientation="Horizontal" Spacing="6">
+        <CalendarDatePicker Name="DatePart" Width="130" />
+        <TimePicker Name="TimePart"
+                    ClockIdentifier="24HourClock"
+                    MinuteIncrement="1"
+                    Width="100" />
+    </StackPanel>
+</UserControl>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Controls/DateTimePicker.axaml.cs

@@ -0,0 +1,169 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Controls;
+
+/// <summary>
+/// A combined date + time picker that exposes a single DateTimeOffset value.
+/// Bridges between CalendarDatePicker (DateTime?) and TimePicker (TimeSpan?)
+/// and the public SelectedDateTime (DateTimeOffset?) property.
+/// </summary>
+public partial class DateTimePicker : UserControl
+{
+    public static readonly StyledProperty<DateTimeOffset?> SelectedDateTimeProperty =
+        AvaloniaProperty.Register<DateTimePicker, DateTimeOffset?>(
+            nameof(SelectedDateTime), defaultValue: DateTimeOffset.Now);
+
+    public static readonly StyledProperty<DateTimeOffset?> MinDateTimeProperty =
+        AvaloniaProperty.Register<DateTimePicker, DateTimeOffset?>(
+            nameof(MinDateTime));
+
+    public static readonly StyledProperty<DateTimeOffset?> MaxDateTimeProperty =
+        AvaloniaProperty.Register<DateTimePicker, DateTimeOffset?>(
+            nameof(MaxDateTime));
+
+    private bool _isUpdating;
+
+    public DateTimePicker()
+    {
+        InitializeComponent();
+    }
+
+    /// <summary>The combined date and time value.</summary>
+    public DateTimeOffset? SelectedDateTime
+    {
+        get => GetValue(SelectedDateTimeProperty);
+        set => SetValue(SelectedDateTimeProperty, value);
+    }
+
+    /// <summary>Optional minimum allowed date/time.</summary>
+    public DateTimeOffset? MinDateTime
+    {
+        get => GetValue(MinDateTimeProperty);
+        set => SetValue(MinDateTimeProperty, value);
+    }
+
+    /// <summary>Optional maximum allowed date/time.</summary>
+    public DateTimeOffset? MaxDateTime
+    {
+        get => GetValue(MaxDateTimeProperty);
+        set => SetValue(MaxDateTimeProperty, value);
+    }
+
+    protected override void OnLoaded(RoutedEventArgs e)
+    {
+        base.OnLoaded(e);
+
+        var datePart = this.FindControl<CalendarDatePicker>("DatePart");
+        var timePart = this.FindControl<TimePicker>("TimePart");
+
+        if (datePart != null)
+            datePart.SelectedDateChanged += OnDatePartChanged;
+        if (timePart != null)
+            timePart.SelectedTimeChanged += OnTimePartChanged;
+
+        // Push initial value to the sub-controls
+        SyncFromDateTime();
+    }
+
+    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+    {
+        base.OnPropertyChanged(change);
+
+        if (_isUpdating) return;
+
+        if (change.Property == SelectedDateTimeProperty)
+            SyncFromDateTime();
+        else if (change.Property == MinDateTimeProperty || change.Property == MaxDateTimeProperty)
+        {
+            ClampDateTime();
+            UpdateCalendarBounds();
+        }
+    }
+
+    private void OnDatePartChanged(object? sender, SelectionChangedEventArgs e)
+    {
+        if (_isUpdating) return;
+        SyncToDateTime();
+    }
+
+    private void OnTimePartChanged(object? sender, TimePickerSelectedValueChangedEventArgs e)
+    {
+        if (_isUpdating) return;
+        SyncToDateTime();
+    }
+
+    private void SyncFromDateTime()
+    {
+        var dt = SelectedDateTime;
+        if (dt == null) return;
+
+        _isUpdating = true;
+        try
+        {
+            var datePart = this.FindControl<CalendarDatePicker>("DatePart");
+            var timePart = this.FindControl<TimePicker>("TimePart");
+
+            if (datePart != null)
+                datePart.SelectedDate = dt.Value.DateTime.Date;
+            if (timePart != null)
+                timePart.SelectedTime = dt.Value.TimeOfDay;
+        }
+        finally
+        {
+            _isUpdating = false;
+        }
+    }
+
+    private void SyncToDateTime()
+    {
+        var datePart = this.FindControl<CalendarDatePicker>("DatePart");
+        var timePart = this.FindControl<TimePicker>("TimePart");
+
+        var date = datePart?.SelectedDate ?? DateTime.Now.Date;
+        var time = timePart?.SelectedTime ?? TimeSpan.Zero;
+
+        _isUpdating = true;
+        try
+        {
+            var combined = new DateTimeOffset(
+                date.Year, date.Month, date.Day,
+                time.Hours, time.Minutes, time.Seconds,
+                DateTimeOffset.Now.Offset);
+            SelectedDateTime = Clamp(combined);
+        }
+        finally
+        {
+            _isUpdating = false;
+        }
+    }
+
+    private void ClampDateTime()
+    {
+        if (SelectedDateTime == null) return;
+
+        var clamped = Clamp(SelectedDateTime.Value);
+        if (clamped != SelectedDateTime)
+            SelectedDateTime = clamped;
+    }
+
+    private DateTimeOffset Clamp(DateTimeOffset value)
+    {
+        if (MinDateTime.HasValue && value < MinDateTime.Value)
+            return MinDateTime.Value;
+        if (MaxDateTime.HasValue && value > MaxDateTime.Value)
+            return MaxDateTime.Value;
+        return value;
+    }
+
+    private void UpdateCalendarBounds()
+    {
+        var datePart = this.FindControl<CalendarDatePicker>("DatePart");
+        if (datePart == null) return;
+
+        datePart.DisplayDateStart = MinDateTime?.DateTime;
+        datePart.DisplayDateEnd = MaxDateTime?.DateTime;
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Controls/DateTimeRangePicker.axaml

@@ -0,0 +1,27 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="ZB.MOM.WW.LmxOpcUa.Client.UI.Controls.DateTimeRangePicker">
+    <StackPanel Orientation="Horizontal" Spacing="8">
+        <StackPanel Spacing="2">
+            <TextBlock Text="Start (UTC)" FontSize="11" Foreground="Gray" />
+            <TextBox Name="StartInput" Width="170" FontFamily="Consolas,monospace" FontSize="13"
+                     Watermark="yyyy-MM-dd HH:mm:ss (UTC)"
+                     Text="{Binding StartText, RelativeSource={RelativeSource AncestorType=UserControl}}" />
+        </StackPanel>
+        <TextBlock Text="to" VerticalAlignment="Bottom" Margin="0,0,0,6" />
+        <StackPanel Spacing="2">
+            <TextBlock Text="End (UTC)" FontSize="11" Foreground="Gray" />
+            <TextBox Name="EndInput" Width="170" FontFamily="Consolas,monospace" FontSize="13"
+                     Watermark="yyyy-MM-dd HH:mm:ss (UTC)"
+                     Text="{Binding EndText, RelativeSource={RelativeSource AncestorType=UserControl}}" />
+        </StackPanel>
+        <Border Background="#F0F0F0" CornerRadius="4" Padding="4,2" VerticalAlignment="Bottom" Margin="0,0,0,2">
+            <StackPanel Orientation="Horizontal" Spacing="4">
+                <Button Name="Last5MinBtn" Content="5m" Padding="8,3" FontSize="11" />
+                <Button Name="LastHourBtn" Content="1h" Padding="8,3" FontSize="11" />
+                <Button Name="LastDayBtn" Content="1d" Padding="8,3" FontSize="11" />
+                <Button Name="LastWeekBtn" Content="1w" Padding="8,3" FontSize="11" />
+            </StackPanel>
+        </Border>
+    </StackPanel>
+</UserControl>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Controls/DateTimeRangePicker.axaml.cs

@@ -0,0 +1,187 @@
+using System;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Media;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Controls;
+
+/// <summary>
+/// A date/time range picker using formatted text boxes and preset duration buttons.
+/// Text properties are two-way bound to TextBoxes via XAML; DateTime properties
+/// are synced in code-behind.
+/// </summary>
+public partial class DateTimeRangePicker : UserControl
+{
+    private const string Format = "yyyy-MM-dd HH:mm:ss";
+
+    public static readonly StyledProperty<DateTimeOffset?> StartDateTimeProperty =
+        AvaloniaProperty.Register<DateTimeRangePicker, DateTimeOffset?>(
+            nameof(StartDateTime), defaultBindingMode: Avalonia.Data.BindingMode.TwoWay);
+
+    public static readonly StyledProperty<DateTimeOffset?> EndDateTimeProperty =
+        AvaloniaProperty.Register<DateTimeRangePicker, DateTimeOffset?>(
+            nameof(EndDateTime), defaultBindingMode: Avalonia.Data.BindingMode.TwoWay);
+
+    public static readonly StyledProperty<string> StartTextProperty =
+        AvaloniaProperty.Register<DateTimeRangePicker, string>(nameof(StartText), defaultValue: "");
+
+    public static readonly StyledProperty<string> EndTextProperty =
+        AvaloniaProperty.Register<DateTimeRangePicker, string>(nameof(EndText), defaultValue: "");
+
+    public static readonly StyledProperty<DateTimeOffset?> MinDateTimeProperty =
+        AvaloniaProperty.Register<DateTimeRangePicker, DateTimeOffset?>(nameof(MinDateTime));
+
+    public static readonly StyledProperty<DateTimeOffset?> MaxDateTimeProperty =
+        AvaloniaProperty.Register<DateTimeRangePicker, DateTimeOffset?>(nameof(MaxDateTime));
+
+    private bool _isUpdating;
+
+    public DateTimeRangePicker()
+    {
+        InitializeComponent();
+    }
+
+    public DateTimeOffset? StartDateTime
+    {
+        get => GetValue(StartDateTimeProperty);
+        set => SetValue(StartDateTimeProperty, value);
+    }
+
+    public DateTimeOffset? EndDateTime
+    {
+        get => GetValue(EndDateTimeProperty);
+        set => SetValue(EndDateTimeProperty, value);
+    }
+
+    public string StartText
+    {
+        get => GetValue(StartTextProperty);
+        set => SetValue(StartTextProperty, value);
+    }
+
+    public string EndText
+    {
+        get => GetValue(EndTextProperty);
+        set => SetValue(EndTextProperty, value);
+    }
+
+    public DateTimeOffset? MinDateTime
+    {
+        get => GetValue(MinDateTimeProperty);
+        set => SetValue(MinDateTimeProperty, value);
+    }
+
+    public DateTimeOffset? MaxDateTime
+    {
+        get => GetValue(MaxDateTimeProperty);
+        set => SetValue(MaxDateTimeProperty, value);
+    }
+
+    protected override void OnLoaded(RoutedEventArgs e)
+    {
+        base.OnLoaded(e);
+
+        var startInput = this.FindControl<TextBox>("StartInput");
+        var endInput = this.FindControl<TextBox>("EndInput");
+
+        if (startInput != null) startInput.LostFocus += OnStartLostFocus;
+        if (endInput != null) endInput.LostFocus += OnEndLostFocus;
+
+        var last5Min = this.FindControl<Button>("Last5MinBtn");
+        var lastHour = this.FindControl<Button>("LastHourBtn");
+        var lastDay = this.FindControl<Button>("LastDayBtn");
+        var lastWeek = this.FindControl<Button>("LastWeekBtn");
+
+        if (last5Min != null) last5Min.Click += (_, _) => ApplyPreset(TimeSpan.FromMinutes(5));
+        if (lastHour != null) lastHour.Click += (_, _) => ApplyPreset(TimeSpan.FromHours(1));
+        if (lastDay != null) lastDay.Click += (_, _) => ApplyPreset(TimeSpan.FromDays(1));
+        if (lastWeek != null) lastWeek.Click += (_, _) => ApplyPreset(TimeSpan.FromDays(7));
+    }
+
+    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+    {
+        base.OnPropertyChanged(change);
+        if (_isUpdating) return;
+
+        if (change.Property == StartDateTimeProperty)
+        {
+            _isUpdating = true;
+            StartText = StartDateTime?.UtcDateTime.ToString(Format) ?? "";
+            _isUpdating = false;
+        }
+        else if (change.Property == EndDateTimeProperty)
+        {
+            _isUpdating = true;
+            EndText = EndDateTime?.UtcDateTime.ToString(Format) ?? "";
+            _isUpdating = false;
+        }
+    }
+
+    private void OnStartLostFocus(object? sender, RoutedEventArgs e)
+    {
+        var startInput = this.FindControl<TextBox>("StartInput");
+        if (startInput == null) return;
+
+        if (TryParseDateTime(startInput.Text, out var dt))
+        {
+            _isUpdating = true;
+            StartDateTime = dt;
+            _isUpdating = false;
+            startInput.Foreground = null;
+        }
+        else if (!string.IsNullOrWhiteSpace(startInput.Text))
+        {
+            startInput.Foreground = Brushes.Red;
+        }
+    }
+
+    private void OnEndLostFocus(object? sender, RoutedEventArgs e)
+    {
+        var endInput = this.FindControl<TextBox>("EndInput");
+        if (endInput == null) return;
+
+        if (TryParseDateTime(endInput.Text, out var dt))
+        {
+            _isUpdating = true;
+            EndDateTime = dt;
+            _isUpdating = false;
+            endInput.Foreground = null;
+        }
+        else if (!string.IsNullOrWhiteSpace(endInput.Text))
+        {
+            endInput.Foreground = Brushes.Red;
+        }
+    }
+
+    private void ApplyPreset(TimeSpan span)
+    {
+        _isUpdating = true;
+        try
+        {
+            var now = DateTimeOffset.UtcNow;
+            StartDateTime = now - span;
+            EndDateTime = now;
+            StartText = StartDateTime.Value.UtcDateTime.ToString(Format);
+            EndText = EndDateTime.Value.UtcDateTime.ToString(Format);
+        }
+        finally
+        {
+            _isUpdating = false;
+        }
+    }
+
+    private static bool TryParseDateTime(string? text, out DateTimeOffset result)
+    {
+        result = default;
+        if (string.IsNullOrWhiteSpace(text)) return false;
+
+        if (DateTimeOffset.TryParseExact(text, Format, CultureInfo.InvariantCulture,
+                DateTimeStyles.AssumeUniversal, out result))
+            return true;
+
+        return DateTimeOffset.TryParse(text, CultureInfo.InvariantCulture,
+            DateTimeStyles.AssumeUniversal, out result);
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Helpers/StatusCodeFormatter.cs

@@ -0,0 +1,36 @@
+using Opc.Ua;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Helpers;
+
+/// <summary>
+/// Formats OPC UA status codes as "0xHEX (description)".
+/// </summary>
+internal static class StatusCodeFormatter
+{
+    public static string Format(StatusCode statusCode)
+    {
+        var code = statusCode.Code;
+        var hex = $"0x{code:X8}";
+
+        // Try the SDK's browse name lookup first
+        var name = StatusCodes.GetBrowseName(code);
+        if (!string.IsNullOrEmpty(name))
+            return $"{hex} ({name})";
+
+        // Try masking to just the main code (top 16 bits) for sub-status codes
+        var mainCode = code & 0xFFFF0000;
+        if (mainCode != code)
+        {
+            name = StatusCodes.GetBrowseName(mainCode);
+            if (!string.IsNullOrEmpty(name))
+                return $"{hex} ({name})";
+        }
+
+        // Fallback to severity category
+        if (StatusCode.IsGood(statusCode))
+            return $"{hex} (Good)";
+        if (StatusCode.IsBad(statusCode))
+            return $"{hex} (Bad)";
+        return $"{hex} (Uncertain)";
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Helpers/ValueFormatter.cs

@@ -0,0 +1,33 @@
+using System.Collections;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Helpers;
+
+/// <summary>
+/// Formats OPC UA values for display, with array support.
+/// </summary>
+internal static class ValueFormatter
+{
+    public static string Format(object? value)
+    {
+        if (value is null) return "(null)";
+        if (value is Array array) return FormatArray(array);
+        if (value is IEnumerable enumerable and not string) return FormatEnumerable(enumerable);
+        return value.ToString() ?? "(null)";
+    }
+
+    private static string FormatArray(Array array)
+    {
+        var elements = new string[array.Length];
+        for (var i = 0; i < array.Length; i++)
+            elements[i] = array.GetValue(i)?.ToString() ?? "null";
+        return $"[{string.Join(",", elements)}]";
+    }
+
+    private static string FormatEnumerable(IEnumerable enumerable)
+    {
+        var items = new List<string>();
+        foreach (var item in enumerable)
+            items.Add(item?.ToString() ?? "null");
+        return $"[{string.Join(",", items)}]";
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Program.cs

@@ -2,7 +2,7 @@ using Avalonia;
 
 namespace ZB.MOM.WW.LmxOpcUa.Client.UI;
 
-internal class Program
+public class Program
 {
     [STAThread]
     public static void Main(string[] args)

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Services/ISettingsService.cs

@@ -0,0 +1,10 @@
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Services;
+
+/// <summary>
+/// Loads and saves user settings.
+/// </summary>
+public interface ISettingsService
+{
+    UserSettings Load();
+    void Save(UserSettings settings);
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Services/JsonSettingsService.cs

@@ -0,0 +1,50 @@
+using System.Text.Json;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Services;
+
+/// <summary>
+/// Persists user settings to a JSON file under LocalApplicationData.
+/// </summary>
+public sealed class JsonSettingsService : ISettingsService
+{
+    private static readonly string SettingsDir = Path.Combine(
+        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+        "LmxOpcUaClient");
+
+    private static readonly string SettingsPath = Path.Combine(SettingsDir, "settings.json");
+
+    private static readonly JsonSerializerOptions JsonOptions = new()
+    {
+        WriteIndented = true
+    };
+
+    public UserSettings Load()
+    {
+        try
+        {
+            if (!File.Exists(SettingsPath))
+                return new UserSettings();
+
+            var json = File.ReadAllText(SettingsPath);
+            return JsonSerializer.Deserialize<UserSettings>(json, JsonOptions) ?? new UserSettings();
+        }
+        catch
+        {
+            return new UserSettings();
+        }
+    }
+
+    public void Save(UserSettings settings)
+    {
+        try
+        {
+            Directory.CreateDirectory(SettingsDir);
+            var json = JsonSerializer.Serialize(settings, JsonOptions);
+            File.WriteAllText(SettingsPath, json);
+        }
+        catch
+        {
+            // Best-effort save; don't crash the app
+        }
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Services/UserSettings.cs

@@ -0,0 +1,20 @@
+using ZB.MOM.WW.LmxOpcUa.Client.Shared.Models;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Services;
+
+/// <summary>
+/// Persisted user connection settings.
+/// </summary>
+public sealed class UserSettings
+{
+    public string EndpointUrl { get; set; } = "opc.tcp://localhost:4840";
+    public string? Username { get; set; }
+    public string? Password { get; set; }
+    public SecurityMode SecurityMode { get; set; } = SecurityMode.None;
+    public string? FailoverUrls { get; set; }
+    public int SessionTimeoutSeconds { get; set; } = 60;
+    public bool AutoAcceptCertificates { get; set; } = true;
+    public string? CertificateStorePath { get; set; }
+    public List<string> SubscribedNodes { get; set; } = [];
+    public string? AlarmSourceNodeId { get; set; }
+}

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

@@ -15,7 +15,9 @@ public class AlarmEventViewModel : ObservableObject
         bool retain,
         bool activeState,
         bool ackedState,
-        DateTime time)
+        DateTime time,
+        byte[]? eventId = null,
+        string? conditionNodeId = null)
     {
         SourceName = sourceName;
         ConditionName = conditionName;
@@ -25,6 +27,8 @@ public class AlarmEventViewModel : ObservableObject
         ActiveState = activeState;
         AckedState = ackedState;
         Time = time;
+        EventId = eventId;
+        ConditionNodeId = conditionNodeId;
     }
 
     public string SourceName { get; }
@@ -35,4 +39,9 @@ public class AlarmEventViewModel : ObservableObject
     public bool ActiveState { get; }
     public bool AckedState { get; }
     public DateTime Time { get; }
-}
+    public byte[]? EventId { get; }
+    public string? ConditionNodeId { get; }
+
+    /// <summary>Whether this alarm can be acknowledged (active, not yet acked, has EventId).</summary>
+    public bool CanAcknowledge => ActiveState && !AckedState && EventId != null && ConditionNodeId != null;
+}

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

@@ -32,6 +32,8 @@ public partial class AlarmsViewModel : ObservableObject
 
     [ObservableProperty] private string? _monitoredNodeIdText;
 
+    [ObservableProperty] private int _activeAlarmCount;
+
     public AlarmsViewModel(IOpcUaClientService service, IUiDispatcher dispatcher)
     {
         _service = service;
@@ -44,17 +46,36 @@ public partial class AlarmsViewModel : ObservableObject
 
     private void OnAlarmEvent(object? sender, AlarmEventArgs e)
     {
+        // Only display alarm/condition events (those with a ConditionName), not generic events
+        if (string.IsNullOrEmpty(e.ConditionName)) return;
+
         _dispatcher.Post(() =>
         {
-            AlarmEvents.Add(new AlarmEventViewModel(
-                e.SourceName,
-                e.ConditionName,
-                e.Severity,
-                e.Message,
-                e.Retain,
-                e.ActiveState,
-                e.AckedState,
-                e.Time));
+            // Find existing row by source + condition and update it, or add new
+            var existing = AlarmEvents.FirstOrDefault(a =>
+                a.SourceName == e.SourceName && a.ConditionName == e.ConditionName);
+
+            if (existing != null)
+            {
+                var index = AlarmEvents.IndexOf(existing);
+                AlarmEvents[index] = new AlarmEventViewModel(
+                    e.SourceName, e.ConditionName, e.Severity, e.Message,
+                    e.Retain, e.ActiveState, e.AckedState, e.Time,
+                    e.EventId, e.ConditionNodeId);
+
+                // Remove alarms that are no longer retained
+                if (!e.Retain)
+                    AlarmEvents.RemoveAt(index);
+            }
+            else if (e.Retain)
+            {
+                AlarmEvents.Add(new AlarmEventViewModel(
+                    e.SourceName, e.ConditionName, e.Severity, e.Message,
+                    e.Retain, e.ActiveState, e.AckedState, e.Time,
+                    e.EventId, e.ConditionNodeId));
+            }
+
+            ActiveAlarmCount = AlarmEvents.Count(a => a.ActiveState && !a.AckedState);
         });
     }
 
@@ -74,6 +95,15 @@ public partial class AlarmsViewModel : ObservableObject
 
             await _service.SubscribeAlarmsAsync(sourceNodeId, Interval);
             IsSubscribed = true;
+
+            try
+            {
+                await _service.RequestConditionRefreshAsync();
+            }
+            catch
+            {
+                // Refresh not supported
+            }
         }
         catch
         {
@@ -113,6 +143,68 @@ public partial class AlarmsViewModel : ObservableObject
         }
     }
 
+    /// <summary>
+    ///     Acknowledges an alarm and returns (success, message).
+    /// </summary>
+    public async Task<(bool Success, string Message)> AcknowledgeAlarmAsync(AlarmEventViewModel alarm, string comment)
+    {
+        if (!IsConnected || alarm.EventId == null || alarm.ConditionNodeId == null)
+            return (false, "Alarm cannot be acknowledged (missing EventId or ConditionId).");
+
+        try
+        {
+            var result = await _service.AcknowledgeAlarmAsync(alarm.ConditionNodeId, alarm.EventId, comment);
+            if (Opc.Ua.StatusCode.IsGood(result))
+                return (true, "Alarm acknowledged successfully.");
+            return (false, $"Acknowledge failed: {Helpers.StatusCodeFormatter.Format(result)}");
+        }
+        catch (Exception ex)
+        {
+            return (false, $"Error: {ex.Message}");
+        }
+    }
+
+    /// <summary>
+    ///     Returns the monitored node ID for persistence, or null if not subscribed.
+    /// </summary>
+    public string? GetAlarmSourceNodeId()
+    {
+        return IsSubscribed ? MonitoredNodeIdText : null;
+    }
+
+    /// <summary>
+    ///     Restores an alarm subscription and requests a condition refresh.
+    /// </summary>
+    public async Task RestoreAlarmSubscriptionAsync(string? sourceNodeId)
+    {
+        if (!IsConnected || string.IsNullOrWhiteSpace(sourceNodeId)) return;
+
+        MonitoredNodeIdText = sourceNodeId;
+
+        try
+        {
+            var nodeId = string.IsNullOrWhiteSpace(sourceNodeId)
+                ? null
+                : NodeId.Parse(sourceNodeId);
+
+            await _service.SubscribeAlarmsAsync(nodeId, Interval);
+            IsSubscribed = true;
+
+            try
+            {
+                await _service.RequestConditionRefreshAsync();
+            }
+            catch
+            {
+                // Refresh not supported
+            }
+        }
+        catch
+        {
+            // Subscribe failed
+        }
+    }
+
     /// <summary>
     ///     Clears alarm events and resets state.
     /// </summary>
@@ -120,6 +212,7 @@ public partial class AlarmsViewModel : ObservableObject
     {
         AlarmEvents.Clear();
         IsSubscribed = false;
+        ActiveAlarmCount = 0;
     }
 
     /// <summary>

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

@@ -16,7 +16,7 @@ public partial class HistoryViewModel : ObservableObject
     private readonly IUiDispatcher _dispatcher;
     private readonly IOpcUaClientService _service;
 
-    [ObservableProperty] private DateTimeOffset _endTime = DateTimeOffset.UtcNow;
+    [ObservableProperty] private DateTimeOffset? _endTime = DateTimeOffset.UtcNow;
 
     [ObservableProperty] private double _intervalMs = 3600000;
 
@@ -32,7 +32,7 @@ public partial class HistoryViewModel : ObservableObject
     [ObservableProperty] [NotifyCanExecuteChangedFor(nameof(ReadHistoryCommand))]
     private string? _selectedNodeId;
 
-    [ObservableProperty] private DateTimeOffset _startTime = DateTimeOffset.UtcNow.AddHours(-1);
+    [ObservableProperty] private DateTimeOffset? _startTime = DateTimeOffset.UtcNow.AddHours(-1);
 
     public HistoryViewModel(IOpcUaClientService service, IUiDispatcher dispatcher)
     {
@@ -80,26 +80,29 @@ public partial class HistoryViewModel : ObservableObject
             var nodeId = NodeId.Parse(SelectedNodeId);
             IReadOnlyList<DataValue> values;
 
+            var start = (StartTime ?? DateTimeOffset.UtcNow.AddHours(-1)).UtcDateTime;
+            var end = (EndTime ?? DateTimeOffset.UtcNow).UtcDateTime;
+
             if (SelectedAggregateType != null)
                 values = await _service.HistoryReadAggregateAsync(
                     nodeId,
-                    StartTime.UtcDateTime,
-                    EndTime.UtcDateTime,
+                    start,
+                    end,
                     SelectedAggregateType.Value,
                     IntervalMs);
             else
                 values = await _service.HistoryReadRawAsync(
                     nodeId,
-                    StartTime.UtcDateTime,
-                    EndTime.UtcDateTime,
+                    start,
+                    end,
                     MaxValues);
 
             _dispatcher.Post(() =>
             {
                 foreach (var dv in values)
                     Results.Add(new HistoryValueViewModel(
-                        dv.Value?.ToString() ?? "(null)",
-                        dv.StatusCode.ToString(),
+                        Helpers.ValueFormatter.Format(dv.Value),
+                        Helpers.StatusCodeFormatter.Format(dv.StatusCode),
                         dv.SourceTimestamp.ToString("O"),
                         dv.ServerTimestamp.ToString("O")));
             });

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

@@ -13,7 +13,11 @@ namespace ZB.MOM.WW.LmxOpcUa.Client.UI.ViewModels;
 public partial class MainWindowViewModel : ObservableObject
 {
     private readonly IUiDispatcher _dispatcher;
-    private readonly IOpcUaClientService _service;
+    private readonly IOpcUaClientServiceFactory _factory;
+    private readonly ISettingsService _settingsService;
+    private IOpcUaClientService? _service;
+    private List<string> _savedSubscribedNodes = [];
+    private string? _savedAlarmSourceNodeId;
 
     [ObservableProperty] private bool _autoAcceptCertificates = true;
 
@@ -50,20 +54,18 @@ public partial class MainWindowViewModel : ObservableObject
 
     [ObservableProperty] private int _subscriptionCount;
 
+    [ObservableProperty] private int _activeAlarmCount;
+
     [ObservableProperty] private string? _username;
 
-    public MainWindowViewModel(IOpcUaClientServiceFactory factory, IUiDispatcher dispatcher)
+    public MainWindowViewModel(IOpcUaClientServiceFactory factory, IUiDispatcher dispatcher,
+        ISettingsService? settingsService = null)
     {
-        _service = factory.Create();
+        _factory = factory;
         _dispatcher = dispatcher;
+        _settingsService = settingsService ?? new JsonSettingsService();
 
-        BrowseTree = new BrowseTreeViewModel(_service, dispatcher);
-        ReadWrite = new ReadWriteViewModel(_service, dispatcher);
-        Subscriptions = new SubscriptionsViewModel(_service, dispatcher);
-        Alarms = new AlarmsViewModel(_service, dispatcher);
-        History = new HistoryViewModel(_service, dispatcher);
-
-        _service.ConnectionStateChanged += OnConnectionStateChanged;
+        LoadSettings();
     }
 
     /// <summary>All available security modes.</summary>
@@ -74,11 +76,44 @@ public partial class MainWindowViewModel : ObservableObject
     /// <summary>The currently selected tree nodes (supports multi-select).</summary>
     public ObservableCollection<TreeNodeViewModel> SelectedTreeNodes { get; } = [];
 
-    public BrowseTreeViewModel BrowseTree { get; }
-    public ReadWriteViewModel ReadWrite { get; }
-    public SubscriptionsViewModel Subscriptions { get; }
-    public AlarmsViewModel Alarms { get; }
-    public HistoryViewModel History { get; }
+    public BrowseTreeViewModel? BrowseTree { get; private set; }
+    public ReadWriteViewModel? ReadWrite { get; private set; }
+    public SubscriptionsViewModel? Subscriptions { get; private set; }
+    public AlarmsViewModel? Alarms { get; private set; }
+    public HistoryViewModel? History { get; private set; }
+
+    public string SubscriptionsTabHeader => SubscriptionCount > 0
+        ? $"Subscriptions ({SubscriptionCount})"
+        : "Subscriptions";
+
+    public string AlarmsTabHeader => ActiveAlarmCount > 0
+        ? $"Alarms ({ActiveAlarmCount})"
+        : "Alarms";
+
+    private void InitializeService()
+    {
+        if (_service != null) return;
+
+        _service = _factory.Create();
+        _service.ConnectionStateChanged += OnConnectionStateChanged;
+
+        BrowseTree = new BrowseTreeViewModel(_service, _dispatcher);
+        ReadWrite = new ReadWriteViewModel(_service, _dispatcher);
+        Subscriptions = new SubscriptionsViewModel(_service, _dispatcher);
+        Alarms = new AlarmsViewModel(_service, _dispatcher);
+        Alarms.PropertyChanged += (_, args) =>
+        {
+            if (args.PropertyName == nameof(AlarmsViewModel.ActiveAlarmCount))
+                _dispatcher.Post(() => ActiveAlarmCount = Alarms.ActiveAlarmCount);
+        };
+        History = new HistoryViewModel(_service, _dispatcher);
+
+        OnPropertyChanged(nameof(BrowseTree));
+        OnPropertyChanged(nameof(ReadWrite));
+        OnPropertyChanged(nameof(Subscriptions));
+        OnPropertyChanged(nameof(Alarms));
+        OnPropertyChanged(nameof(History));
+    }
 
     private void OnConnectionStateChanged(object? sender, ConnectionStateChangedEventArgs e)
     {
@@ -90,10 +125,10 @@ public partial class MainWindowViewModel : ObservableObject
         OnPropertyChanged(nameof(IsConnected));
 
         var connected = value == ConnectionState.Connected;
-        ReadWrite.IsConnected = connected;
-        Subscriptions.IsConnected = connected;
-        Alarms.IsConnected = connected;
-        History.IsConnected = connected;
+        if (ReadWrite != null) ReadWrite.IsConnected = connected;
+        if (Subscriptions != null) Subscriptions.IsConnected = connected;
+        if (Alarms != null) Alarms.IsConnected = connected;
+        if (History != null) History.IsConnected = connected;
 
         switch (value)
         {
@@ -110,20 +145,31 @@ public partial class MainWindowViewModel : ObservableObject
                 StatusMessage = "Disconnected";
                 SessionLabel = string.Empty;
                 RedundancyInfo = null;
-                BrowseTree.Clear();
-                ReadWrite.Clear();
-                Subscriptions.Clear();
-                Alarms.Clear();
-                History.Clear();
+                BrowseTree?.Clear();
+                ReadWrite?.Clear();
+                Subscriptions?.Clear();
+                Alarms?.Clear();
+                History?.Clear();
                 SubscriptionCount = 0;
+                ActiveAlarmCount = 0;
                 break;
         }
     }
 
     partial void OnSelectedTreeNodeChanged(TreeNodeViewModel? value)
     {
-        ReadWrite.SelectedNodeId = value?.NodeId;
-        History.SelectedNodeId = value?.NodeId;
+        if (ReadWrite != null) ReadWrite.SelectedNodeId = value?.NodeId;
+        if (History != null) History.SelectedNodeId = value?.NodeId;
+    }
+
+    partial void OnSubscriptionCountChanged(int value)
+    {
+        OnPropertyChanged(nameof(SubscriptionsTabHeader));
+    }
+
+    partial void OnActiveAlarmCountChanged(int value)
+    {
+        OnPropertyChanged(nameof(AlarmsTabHeader));
     }
 
     private bool CanConnect()
@@ -139,6 +185,8 @@ public partial class MainWindowViewModel : ObservableObject
             ConnectionState = ConnectionState.Connecting;
             StatusMessage = "Connecting...";
 
+            InitializeService();
+
             var settings = new ConnectionSettings
             {
                 EndpointUrl = EndpointUrl,
@@ -152,7 +200,7 @@ public partial class MainWindowViewModel : ObservableObject
             };
             settings.Validate();
 
-            var info = await _service.ConnectAsync(settings);
+            var info = await _service!.ConnectAsync(settings);
 
             _dispatcher.Post(() =>
             {
@@ -163,7 +211,7 @@ public partial class MainWindowViewModel : ObservableObject
             // Load redundancy info
             try
             {
-                var redundancy = await _service.GetRedundancyInfoAsync();
+                var redundancy = await _service!.GetRedundancyInfoAsync();
                 _dispatcher.Post(() => RedundancyInfo = redundancy);
             }
             catch
@@ -173,6 +221,19 @@ public partial class MainWindowViewModel : ObservableObject
 
             // Load root nodes
             await BrowseTree.LoadRootsAsync();
+
+            // Restore saved subscriptions
+            if (_savedSubscribedNodes.Count > 0 && Subscriptions != null)
+            {
+                await Subscriptions.RestoreSubscriptionsAsync(_savedSubscribedNodes);
+                SubscriptionCount = Subscriptions.SubscriptionCount;
+            }
+
+            // Restore saved alarm subscription
+            if (!string.IsNullOrEmpty(_savedAlarmSourceNodeId) && Alarms != null)
+                await Alarms.RestoreAlarmSubscriptionAsync(_savedAlarmSourceNodeId);
+
+            SaveSettings();
         }
         catch (Exception ex)
         {
@@ -195,9 +256,10 @@ public partial class MainWindowViewModel : ObservableObject
     {
         try
         {
-            Subscriptions.Teardown();
-            Alarms.Teardown();
-            await _service.DisconnectAsync();
+            SaveSettings();
+            Subscriptions?.Teardown();
+            Alarms?.Teardown();
+            await _service!.DisconnectAsync();
         }
         catch
         {
@@ -217,8 +279,11 @@ public partial class MainWindowViewModel : ObservableObject
     {
         if (SelectedTreeNodes.Count == 0 || !IsConnected) return;
 
+        if (Subscriptions == null) return;
+
         var nodes = SelectedTreeNodes.ToList();
-        foreach (var node in nodes) await Subscriptions.AddSubscriptionForNodeAsync(node.NodeId);
+        foreach (var node in nodes)
+            await Subscriptions.AddSubscriptionRecursiveAsync(node.NodeId, node.NodeClass);
 
         SubscriptionCount = Subscriptions.SubscriptionCount;
         SelectedTabIndex = 1; // Subscriptions tab
@@ -237,6 +302,32 @@ public partial class MainWindowViewModel : ObservableObject
         SelectedTabIndex = 3; // History tab
     }
 
+    /// <summary>
+    ///     Stops any active alarm subscription, subscribes to alarms on the selected node,
+    ///     and switches to the Alarms tab.
+    /// </summary>
+    [RelayCommand]
+    private async Task MonitorAlarmsForSelectedNodeAsync()
+    {
+        if (SelectedTreeNodes.Count == 0 || !IsConnected || Alarms == null) return;
+
+        var node = SelectedTreeNodes[0];
+
+        // Stop existing alarm subscription if active
+        if (Alarms.IsSubscribed)
+        {
+            try { await _service!.UnsubscribeAlarmsAsync(); }
+            catch { /* best effort */ }
+            Alarms.Clear();
+        }
+
+        // Subscribe to the selected node
+        Alarms.MonitoredNodeIdText = node.NodeId;
+        await Alarms.SubscribeCommand.ExecuteAsync(null);
+
+        SelectedTabIndex = 2; // Alarms tab
+    }
+
     /// <summary>
     ///     Updates whether "View History" should be enabled based on the selected node's type.
     ///     Only Variable nodes can have history.
@@ -248,6 +339,39 @@ public partial class MainWindowViewModel : ObservableObject
                                        && SelectedTreeNodes[0].NodeClass == "Variable";
     }
 
+    private void LoadSettings()
+    {
+        var s = _settingsService.Load();
+        EndpointUrl = s.EndpointUrl;
+        Username = s.Username;
+        Password = s.Password;
+        SelectedSecurityMode = s.SecurityMode;
+        FailoverUrls = s.FailoverUrls;
+        SessionTimeoutSeconds = s.SessionTimeoutSeconds;
+        AutoAcceptCertificates = s.AutoAcceptCertificates;
+        if (!string.IsNullOrEmpty(s.CertificateStorePath))
+            CertificateStorePath = s.CertificateStorePath;
+        _savedSubscribedNodes = s.SubscribedNodes;
+        _savedAlarmSourceNodeId = s.AlarmSourceNodeId;
+    }
+
+    public void SaveSettings()
+    {
+        _settingsService.Save(new UserSettings
+        {
+            EndpointUrl = EndpointUrl,
+            Username = Username,
+            Password = Password,
+            SecurityMode = SelectedSecurityMode,
+            FailoverUrls = FailoverUrls,
+            SessionTimeoutSeconds = SessionTimeoutSeconds,
+            AutoAcceptCertificates = AutoAcceptCertificates,
+            CertificateStorePath = CertificateStorePath,
+            SubscribedNodes = Subscriptions?.GetSubscribedNodeIds() ?? _savedSubscribedNodes,
+            AlarmSourceNodeId = Alarms?.GetAlarmSourceNodeId() ?? _savedAlarmSourceNodeId
+        });
+    }
+
     private static string[]? ParseFailoverUrls(string? csv)
     {
         if (string.IsNullOrWhiteSpace(csv))

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

@@ -72,8 +72,8 @@ public partial class ReadWriteViewModel : ObservableObject
 
             _dispatcher.Post(() =>
             {
-                CurrentValue = dataValue.Value?.ToString() ?? "(null)";
-                CurrentStatus = dataValue.StatusCode.ToString();
+                CurrentValue = Helpers.ValueFormatter.Format(dataValue.Value);
+                CurrentStatus = Helpers.StatusCodeFormatter.Format(dataValue.StatusCode);
                 SourceTimestamp = dataValue.SourceTimestamp.ToString("O");
                 ServerTimestamp = dataValue.ServerTimestamp.ToString("O");
             });

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

@@ -41,6 +41,9 @@ public partial class SubscriptionsViewModel : ObservableObject
     /// <summary>Currently active subscriptions.</summary>
     public ObservableCollection<SubscriptionItemViewModel> ActiveSubscriptions { get; } = [];
 
+    /// <summary>Currently selected subscriptions (for multi-select remove).</summary>
+    public List<SubscriptionItemViewModel> SelectedSubscriptions { get; } = [];
+
     private void OnDataChanged(object? sender, DataChangedEventArgs e)
     {
         _dispatcher.Post(() =>
@@ -48,8 +51,8 @@ public partial class SubscriptionsViewModel : ObservableObject
             foreach (var item in ActiveSubscriptions)
                 if (item.NodeId == e.NodeId)
                 {
-                    item.Value = e.Value.Value?.ToString() ?? "(null)";
-                    item.Status = e.Value.StatusCode.ToString();
+                    item.Value = Helpers.ValueFormatter.Format(e.Value.Value);
+                    item.Status = Helpers.StatusCodeFormatter.Format(e.Value.StatusCode);
                     item.Timestamp = e.Value.SourceTimestamp.ToString("O");
                 }
         });
@@ -87,31 +90,34 @@ public partial class SubscriptionsViewModel : ObservableObject
 
     private bool CanRemoveSubscription()
     {
-        return IsConnected && SelectedSubscription != null;
+        return IsConnected && (SelectedSubscriptions.Count > 0 || SelectedSubscription != null);
     }
 
     [RelayCommand(CanExecute = nameof(CanRemoveSubscription))]
     private async Task RemoveSubscriptionAsync()
     {
-        if (SelectedSubscription == null) return;
+        var itemsToRemove = SelectedSubscriptions.Count > 0
+            ? SelectedSubscriptions.ToList()
+            : SelectedSubscription != null ? [SelectedSubscription] : [];
 
-        var item = SelectedSubscription;
+        if (itemsToRemove.Count == 0) return;
 
-        try
+        foreach (var item in itemsToRemove)
         {
-            var nodeId = NodeId.Parse(item.NodeId);
-            await _service.UnsubscribeAsync(nodeId);
-
-            _dispatcher.Post(() =>
+            try
             {
-                ActiveSubscriptions.Remove(item);
-                SubscriptionCount = ActiveSubscriptions.Count;
-            });
-        }
-        catch
-        {
-            // Unsubscribe failed
+                var nodeId = NodeId.Parse(item.NodeId);
+                await _service.UnsubscribeAsync(nodeId);
+
+                _dispatcher.Post(() => ActiveSubscriptions.Remove(item));
+            }
+            catch
+            {
+                // Unsubscribe failed for this item; continue with others
+            }
         }
+
+        _dispatcher.Post(() => SubscriptionCount = ActiveSubscriptions.Count);
     }
 
     /// <summary>
@@ -141,6 +147,102 @@ public partial class SubscriptionsViewModel : ObservableObject
         }
     }
 
+    /// <summary>
+    ///     Subscribes to a node and all its Variable descendants recursively.
+    ///     Object nodes are browsed for children; Variable nodes are subscribed directly.
+    /// </summary>
+    public Task AddSubscriptionRecursiveAsync(string nodeIdStr, string nodeClass, int intervalMs = 1000)
+    {
+        return AddSubscriptionRecursiveAsync(nodeIdStr, nodeClass, intervalMs, maxDepth: 10, currentDepth: 0);
+    }
+
+    private async Task AddSubscriptionRecursiveAsync(string nodeIdStr, string nodeClass, int intervalMs, int maxDepth, int currentDepth)
+    {
+        if (!IsConnected || string.IsNullOrWhiteSpace(nodeIdStr)) return;
+        if (currentDepth >= maxDepth) return;
+
+        if (nodeClass == "Variable")
+        {
+            await AddSubscriptionForNodeAsync(nodeIdStr, intervalMs);
+            return;
+        }
+
+        // Browse children and recurse
+        try
+        {
+            var nodeId = NodeId.Parse(nodeIdStr);
+            var children = await _service.BrowseAsync(nodeId);
+
+            foreach (var child in children)
+                await AddSubscriptionRecursiveAsync(child.NodeId, child.NodeClass, intervalMs, maxDepth, currentDepth + 1);
+        }
+        catch
+        {
+            // Browse failed for this node; skip it
+        }
+    }
+
+    /// <summary>
+    ///     Returns the node IDs of all active subscriptions for persistence.
+    /// </summary>
+    public List<string> GetSubscribedNodeIds()
+    {
+        return ActiveSubscriptions.Select(s => s.NodeId).ToList();
+    }
+
+    /// <summary>
+    ///     Restores subscriptions from a saved list of node IDs.
+    /// </summary>
+    public async Task RestoreSubscriptionsAsync(IEnumerable<string> nodeIds)
+    {
+        foreach (var nodeId in nodeIds)
+            await AddSubscriptionForNodeAsync(nodeId);
+    }
+
+    /// <summary>
+    ///     Reads the current value of a node to determine its type, validates that the raw
+    ///     input can be parsed to that type, writes the value, and returns (success, message).
+    /// </summary>
+    public async Task<(bool Success, string Message)> ValidateAndWriteAsync(string nodeIdStr, string rawValue)
+    {
+        try
+        {
+            var nodeId = NodeId.Parse(nodeIdStr);
+
+            // Read current value to determine target type
+            var currentDataValue = await _service.ReadValueAsync(nodeId);
+            var currentValue = currentDataValue.Value;
+
+            // Try parsing to the target type before writing
+            try
+            {
+                Shared.Helpers.ValueConverter.ConvertValue(rawValue, currentValue);
+            }
+            catch (FormatException ex)
+            {
+                var typeName = currentValue?.GetType().Name ?? "unknown";
+                return (false, $"Cannot parse \"{rawValue}\" as {typeName}: {ex.Message}");
+            }
+            catch (OverflowException ex)
+            {
+                var typeName = currentValue?.GetType().Name ?? "unknown";
+                return (false, $"Value \"{rawValue}\" is out of range for {typeName}: {ex.Message}");
+            }
+
+            var result = await _service.WriteValueAsync(nodeId, rawValue);
+            var statusText = Helpers.StatusCodeFormatter.Format(result);
+
+            if (Opc.Ua.StatusCode.IsGood(result))
+                return (true, statusText);
+
+            return (false, $"Write failed: {statusText}");
+        }
+        catch (Exception ex)
+        {
+            return (false, $"Error: {ex.Message}");
+        }
+    }
+
     /// <summary>
     ///     Clears all subscriptions and resets state.
     /// </summary>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/AckAlarmWindow.axaml

@@ -0,0 +1,39 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:Class="ZB.MOM.WW.LmxOpcUa.Client.UI.Views.AckAlarmWindow"
+        Title="Acknowledge Alarm"
+        Width="420"
+        SizeToContent="Height"
+        MinHeight="240"
+        WindowStartupLocation="CenterOwner"
+        CanResize="False">
+    <StackPanel Margin="16" Spacing="12">
+        <TextBlock Text="Acknowledge Alarm" FontWeight="Bold" FontSize="16" />
+
+        <StackPanel Spacing="4">
+            <TextBlock Text="Source:" FontSize="12" Foreground="Gray" />
+            <TextBlock Name="SourceText" FontWeight="SemiBold" />
+        </StackPanel>
+
+        <StackPanel Spacing="4">
+            <TextBlock Text="Condition:" FontSize="12" Foreground="Gray" />
+            <TextBlock Name="ConditionText" />
+        </StackPanel>
+
+        <StackPanel Spacing="4">
+            <TextBlock Text="Comment:" FontSize="12" Foreground="Gray" />
+            <TextBox Name="CommentInput"
+                     Watermark="Enter acknowledgment comment"
+                     AcceptsReturn="True"
+                     Height="60"
+                     TextWrapping="Wrap" />
+        </StackPanel>
+
+        <TextBlock Name="ResultText" Foreground="Gray" />
+
+        <StackPanel Orientation="Horizontal" Spacing="8" HorizontalAlignment="Right">
+            <Button Name="AckButton" Content="Acknowledge" />
+            <Button Name="CancelButton" Content="Cancel" />
+        </StackPanel>
+    </StackPanel>
+</Window>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/AckAlarmWindow.axaml.cs

@@ -0,0 +1,67 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Media;
+using ZB.MOM.WW.LmxOpcUa.Client.UI.ViewModels;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Views;
+
+public partial class AckAlarmWindow : Window
+{
+    private readonly AlarmsViewModel _alarmsVm;
+    private readonly AlarmEventViewModel _alarm;
+
+    public AckAlarmWindow()
+    {
+        InitializeComponent();
+        _alarmsVm = null!;
+        _alarm = null!;
+    }
+
+    public AckAlarmWindow(AlarmsViewModel alarmsVm, AlarmEventViewModel alarm)
+    {
+        InitializeComponent();
+        _alarmsVm = alarmsVm;
+        _alarm = alarm;
+
+        var sourceText = this.FindControl<TextBlock>("SourceText");
+        if (sourceText != null) sourceText.Text = alarm.SourceName;
+
+        var conditionText = this.FindControl<TextBlock>("ConditionText");
+        if (conditionText != null) conditionText.Text = $"{alarm.ConditionName} (Severity: {alarm.Severity})";
+
+        var ackButton = this.FindControl<Button>("AckButton");
+        if (ackButton != null) ackButton.Click += OnAckClicked;
+
+        var cancelButton = this.FindControl<Button>("CancelButton");
+        if (cancelButton != null) cancelButton.Click += OnCancelClicked;
+    }
+
+    private async void OnAckClicked(object? sender, RoutedEventArgs e)
+    {
+        var commentInput = this.FindControl<TextBox>("CommentInput");
+        var resultText = this.FindControl<TextBlock>("ResultText");
+        if (commentInput == null || resultText == null) return;
+
+        var comment = commentInput.Text ?? string.Empty;
+
+        resultText.Foreground = Brushes.Gray;
+        resultText.Text = "Acknowledging...";
+
+        var (success, message) = await _alarmsVm.AcknowledgeAlarmAsync(_alarm, comment);
+
+        if (success)
+        {
+            Close();
+        }
+        else
+        {
+            resultText.Foreground = Brushes.Red;
+            resultText.Text = message;
+        }
+    }
+
+    private void OnCancelClicked(object? sender, RoutedEventArgs e)
+    {
+        Close();
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/AlarmsView.axaml

@@ -17,20 +17,23 @@
         </StackPanel>
 
         <!-- Alarm Events -->
-        <DataGrid ItemsSource="{Binding AlarmEvents}"
+        <DataGrid Name="AlarmsGrid"
+                  ItemsSource="{Binding AlarmEvents}"
                   AutoGenerateColumns="False"
                   IsReadOnly="True"
-                  Margin="0,8,0,0">
+                  HorizontalScrollBarVisibility="Auto"
+                  Margin="0,8,0,0"
+                  LoadingRow="OnDataGridLoadingRow">
             <DataGrid.Columns>
-                <DataGridTextColumn Header="Time" Binding="{Binding Time}" Width="180" />
-                <DataGridTextColumn Header="Source" Binding="{Binding SourceName}" Width="120" />
-                <DataGridTextColumn Header="Condition" Binding="{Binding ConditionName}" Width="120" />
-                <DataGridTextColumn Header="Severity" Binding="{Binding Severity}" Width="80" />
-                <DataGridTextColumn Header="Message" Binding="{Binding Message}" Width="200" />
-                <DataGridCheckBoxColumn Header="Active" Binding="{Binding ActiveState}" Width="60" />
-                <DataGridCheckBoxColumn Header="Acked" Binding="{Binding AckedState}" Width="60" />
-                <DataGridCheckBoxColumn Header="Retain" Binding="{Binding Retain}" Width="60" />
+                <DataGridTextColumn Header="Time" Binding="{Binding Time, StringFormat='{}{0:yyyy-MM-dd HH:mm:ss}'}" Width="Auto" />
+                <DataGridTextColumn Header="Source" Binding="{Binding SourceName}" Width="Auto" />
+                <DataGridTextColumn Header="Condition" Binding="{Binding ConditionName}" Width="Auto" />
+                <DataGridTextColumn Header="Severity" Binding="{Binding Severity}" Width="Auto" />
+                <DataGridTextColumn Header="Message" Binding="{Binding Message}" Width="Auto" />
+                <DataGridCheckBoxColumn Header="Active" Binding="{Binding ActiveState}" Width="Auto" />
+                <DataGridCheckBoxColumn Header="Acked" Binding="{Binding AckedState}" Width="Auto" />
+                <DataGridCheckBoxColumn Header="Retain" Binding="{Binding Retain}" Width="Auto" />
             </DataGrid.Columns>
         </DataGrid>
     </DockPanel>
-</UserControl>
+</UserControl>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/AlarmsView.axaml.cs

@@ -1,11 +1,79 @@
+using System.ComponentModel;
 using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Media;
+using Avalonia.VisualTree;
+using ZB.MOM.WW.LmxOpcUa.Client.UI.ViewModels;
 
 namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Views;
 
 public partial class AlarmsView : UserControl
 {
+    // Severity color bands (OPC UA severity 0-1000)
+    private static readonly IBrush InactiveBrush = new SolidColorBrush(Color.Parse("#F0F0F0"));     // light grey
+    private static readonly IBrush LowBrush = new SolidColorBrush(Color.Parse("#DBEAFE"));          // light blue (1-332)
+    private static readonly IBrush MediumBrush = new SolidColorBrush(Color.Parse("#FEF3C7"));       // light yellow (333-665)
+    private static readonly IBrush HighBrush = new SolidColorBrush(Color.Parse("#FEE2E2"));         // light red (666-899)
+    private static readonly IBrush CriticalBrush = new SolidColorBrush(Color.Parse("#FECACA"));     // red (900-1000)
+
     public AlarmsView()
     {
         InitializeComponent();
     }
-}
+
+    protected override void OnLoaded(RoutedEventArgs e)
+    {
+        base.OnLoaded(e);
+
+        var grid = this.FindControl<DataGrid>("AlarmsGrid");
+        if (grid == null) return;
+
+        var contextMenu = new ContextMenu();
+        var ackItem = new MenuItem { Header = "Acknowledge..." };
+        ackItem.Click += OnAcknowledgeClicked;
+        contextMenu.Items.Add(ackItem);
+        contextMenu.Opening += OnContextMenuOpening;
+        grid.ContextMenu = contextMenu;
+    }
+
+    private void OnDataGridLoadingRow(object? sender, DataGridRowEventArgs e)
+    {
+        if (e.Row.DataContext is AlarmEventViewModel alarm)
+            e.Row.Background = GetSeverityBrush(alarm);
+    }
+
+    private static IBrush GetSeverityBrush(AlarmEventViewModel alarm)
+    {
+        if (!alarm.ActiveState)
+            return InactiveBrush;
+
+        return alarm.Severity switch
+        {
+            >= 900 => CriticalBrush,
+            >= 666 => HighBrush,
+            >= 333 => MediumBrush,
+            _ => LowBrush
+        };
+    }
+
+    private void OnContextMenuOpening(object? sender, CancelEventArgs e)
+    {
+        var grid = this.FindControl<DataGrid>("AlarmsGrid");
+        if (grid?.SelectedItem is not AlarmEventViewModel alarm || !alarm.CanAcknowledge)
+            e.Cancel = true;
+    }
+
+    private void OnAcknowledgeClicked(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is not AlarmsViewModel vm) return;
+
+        var grid = this.FindControl<DataGrid>("AlarmsGrid");
+        if (grid?.SelectedItem is not AlarmEventViewModel alarm || !alarm.CanAcknowledge) return;
+
+        var parentWindow = this.FindAncestorOfType<Window>();
+        if (parentWindow == null) return;
+
+        var ackWindow = new AckAlarmWindow(vm, alarm);
+        ackWindow.ShowDialog(parentWindow);
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/HistoryView.axaml

@@ -1,33 +1,24 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:vm="using:ZB.MOM.WW.LmxOpcUa.Client.UI.ViewModels"
+             xmlns:controls="using:ZB.MOM.WW.LmxOpcUa.Client.UI.Controls"
              x:Class="ZB.MOM.WW.LmxOpcUa.Client.UI.Views.HistoryView"
              x:DataType="vm:HistoryViewModel">
     <DockPanel Margin="8">
         <!-- Controls -->
-        <StackPanel DockPanel.Dock="Top" Spacing="8">
+        <StackPanel DockPanel.Dock="Top" Spacing="10">
             <TextBlock Text="History Read" FontWeight="Bold" />
             <TextBlock Text="{Binding SelectedNodeId, FallbackValue='(no node selected)'}"
                        Foreground="Gray" />
 
-            <StackPanel Orientation="Horizontal" Spacing="8">
-                <StackPanel Spacing="2">
-                    <TextBlock Text="Start Time" FontSize="11" />
-                    <DatePicker SelectedDate="{Binding StartTime}" />
-                </StackPanel>
-                <StackPanel Spacing="2">
-                    <TextBlock Text="End Time" FontSize="11" />
-                    <DatePicker SelectedDate="{Binding EndTime}" />
-                </StackPanel>
-                <StackPanel Spacing="2">
-                    <TextBlock Text="Max Values" FontSize="11" />
-                    <NumericUpDown Value="{Binding MaxValues}" Minimum="1" Maximum="100000" Width="120" />
-                </StackPanel>
-            </StackPanel>
+            <!-- Row 1: Time range -->
+            <controls:DateTimeRangePicker StartDateTime="{Binding StartTime, Mode=TwoWay}"
+                                          EndDateTime="{Binding EndTime, Mode=TwoWay}" />
 
-            <StackPanel Orientation="Horizontal" Spacing="8">
+            <!-- Row 2: Aggregate, Interval, Max Values, Read button -->
+            <StackPanel Orientation="Horizontal" Spacing="12">
                 <StackPanel Spacing="2">
-                    <TextBlock Text="Aggregate" FontSize="11" />
+                    <TextBlock Text="Aggregate" FontSize="11" Foreground="Gray" />
                     <ComboBox ItemsSource="{Binding AggregateTypes}"
                               SelectedItem="{Binding SelectedAggregateType}"
                               Width="150">
@@ -39,12 +30,17 @@
                     </ComboBox>
                 </StackPanel>
                 <StackPanel Spacing="2" IsVisible="{Binding IsAggregateRead}">
-                    <TextBlock Text="Interval (ms)" FontSize="11" />
+                    <TextBlock Text="Interval (ms)" FontSize="11" Foreground="Gray" />
                     <NumericUpDown Value="{Binding IntervalMs}" Minimum="1000" Maximum="86400000" Width="150" />
                 </StackPanel>
+                <StackPanel Spacing="2">
+                    <TextBlock Text="Max Values" FontSize="11" Foreground="Gray" />
+                    <NumericUpDown Value="{Binding MaxValues}" Minimum="1" Maximum="100000" Width="120" />
+                </StackPanel>
                 <Button Content="Read History"
                         Command="{Binding ReadHistoryCommand}"
-                        VerticalAlignment="Bottom" />
+                        VerticalAlignment="Bottom"
+                        Padding="16,6" />
             </StackPanel>
 
             <ProgressBar IsIndeterminate="True"
@@ -56,13 +52,14 @@
         <DataGrid ItemsSource="{Binding Results}"
                   AutoGenerateColumns="False"
                   IsReadOnly="True"
+                  HorizontalScrollBarVisibility="Auto"
                   Margin="0,8,0,0">
             <DataGrid.Columns>
-                <DataGridTextColumn Header="Value" Binding="{Binding Value}" Width="200" />
-                <DataGridTextColumn Header="Status" Binding="{Binding Status}" Width="120" />
-                <DataGridTextColumn Header="Source Timestamp" Binding="{Binding SourceTimestamp}" Width="220" />
-                <DataGridTextColumn Header="Server Timestamp" Binding="{Binding ServerTimestamp}" Width="220" />
+                <DataGridTextColumn Header="Value" Binding="{Binding Value}" Width="Auto" />
+                <DataGridTextColumn Header="Status" Binding="{Binding Status}" Width="Auto" />
+                <DataGridTextColumn Header="Source Timestamp" Binding="{Binding SourceTimestamp}" Width="Auto" />
+                <DataGridTextColumn Header="Server Timestamp" Binding="{Binding ServerTimestamp}" Width="Auto" />
             </DataGrid.Columns>
         </DataGrid>
     </DockPanel>
-</UserControl>
+</UserControl>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/MainWindow.axaml

@@ -4,59 +4,106 @@
         xmlns:views="using:ZB.MOM.WW.LmxOpcUa.Client.UI.Views"
         x:Class="ZB.MOM.WW.LmxOpcUa.Client.UI.Views.MainWindow"
         x:DataType="vm:MainWindowViewModel"
-        Title="LmxOpcUa Client"
+        Title="OPC UA Client"
         Width="1200"
         Height="800">
     <DockPanel>
         <!-- Top Connection Bar -->
-        <Border DockPanel.Dock="Top" Background="#F0F0F0" Padding="8">
-            <StackPanel Spacing="8">
+        <Border DockPanel.Dock="Top" Background="#F0F0F0" Padding="12">
+            <StackPanel Spacing="4">
+                <!-- Always visible: URL + Connect/Disconnect -->
                 <StackPanel Orientation="Horizontal" Spacing="8">
-                    <TextBox Text="{Binding EndpointUrl}"
-                             Width="300"
-                             Watermark="opc.tcp://host:port" />
-                    <TextBox Text="{Binding Username}"
-                             Width="120"
-                             Watermark="Username" />
-                    <TextBox Text="{Binding Password}"
-                             Width="120"
-                             Watermark="Password"
-                             PasswordChar="*" />
-                    <ComboBox ItemsSource="{Binding SecurityModes}"
-                              SelectedItem="{Binding SelectedSecurityMode}"
-                              Width="140" />
+                    <StackPanel Spacing="2" VerticalAlignment="Bottom">
+                        <TextBlock Text="Endpoint URL" FontSize="11" Foreground="Gray" />
+                        <TextBox Text="{Binding EndpointUrl}"
+                                 Width="400"
+                                 Watermark="opc.tcp://host:port" />
+                    </StackPanel>
                     <Button Content="Connect"
-                            Command="{Binding ConnectCommand}" />
+                            Command="{Binding ConnectCommand}"
+                            VerticalAlignment="Bottom" Padding="16,6" />
                     <Button Content="Disconnect"
-                            Command="{Binding DisconnectCommand}" />
-                </StackPanel>
-                <StackPanel Orientation="Horizontal" Spacing="8">
-                    <TextBox Text="{Binding FailoverUrls}"
-                             Width="300"
-                             Watermark="Failover URLs (comma-separated)" />
-                    <TextBlock Text="Timeout (s):" VerticalAlignment="Center" />
-                    <NumericUpDown Value="{Binding SessionTimeoutSeconds}"
-                                   Minimum="1" Maximum="3600"
-                                   Width="90"
-                                   FormatString="0" />
-                    <CheckBox IsChecked="{Binding AutoAcceptCertificates}"
-                              Content="Auto-accept certificates"
-                              VerticalAlignment="Center" />
-                    <TextBox Text="{Binding CertificateStorePath}"
-                             Width="200"
-                             Watermark="Certificate store path" />
+                            Command="{Binding DisconnectCommand}"
+                            VerticalAlignment="Bottom" Padding="16,6" />
                 </StackPanel>
 
+                <!-- Expandable settings -->
+                <Expander Header="Connection Settings" Padding="0,4">
+                    <StackPanel Spacing="10" Margin="4,8,4,4">
+                        <!-- Row 1: Authentication -->
+                        <StackPanel Orientation="Horizontal" Spacing="12">
+                            <StackPanel Spacing="2">
+                                <TextBlock Text="Username" FontSize="11" Foreground="Gray" />
+                                <TextBox Text="{Binding Username}"
+                                         Width="160"
+                                         Watermark="(anonymous)" />
+                            </StackPanel>
+                            <StackPanel Spacing="2">
+                                <TextBlock Text="Password" FontSize="11" Foreground="Gray" />
+                                <TextBox Text="{Binding Password}"
+                                         Width="160"
+                                         Watermark="(none)"
+                                         PasswordChar="*" />
+                            </StackPanel>
+                            <StackPanel Spacing="2">
+                                <TextBlock Text="Security Mode" FontSize="11" Foreground="Gray" />
+                                <ComboBox ItemsSource="{Binding SecurityModes}"
+                                          SelectedItem="{Binding SelectedSecurityMode}"
+                                          Width="160" />
+                            </StackPanel>
+                        </StackPanel>
+
+                        <!-- Row 2: Failover + Session -->
+                        <StackPanel Orientation="Horizontal" Spacing="12">
+                            <StackPanel Spacing="2">
+                                <TextBlock Text="Failover URLs (comma-separated)" FontSize="11" Foreground="Gray" />
+                                <TextBox Text="{Binding FailoverUrls}"
+                                         Width="400"
+                                         Watermark="opc.tcp://backup1:4840, opc.tcp://backup2:4840" />
+                            </StackPanel>
+                            <StackPanel Spacing="2">
+                                <TextBlock Text="Session Timeout (s)" FontSize="11" Foreground="Gray" />
+                                <NumericUpDown Value="{Binding SessionTimeoutSeconds}"
+                                               Minimum="1" Maximum="3600"
+                                               Width="120"
+                                               FormatString="0" />
+                            </StackPanel>
+                        </StackPanel>
+
+                        <!-- Row 3: Certificates -->
+                        <StackPanel Orientation="Horizontal" Spacing="12">
+                            <StackPanel Spacing="2">
+                                <TextBlock Text="Certificate Store Path" FontSize="11" Foreground="Gray" />
+                                <StackPanel Orientation="Horizontal" Spacing="4">
+                                    <TextBox Text="{Binding CertificateStorePath}"
+                                             Width="370"
+                                             IsReadOnly="True"
+                                             Watermark="(default: AppData/LmxOpcUaClient/pki)" />
+                                    <Button Name="BrowseCertPathButton"
+                                            Content="..."
+                                            Width="30"
+                                            ToolTip.Tip="Browse for folder" />
+                                </StackPanel>
+                            </StackPanel>
+                            <CheckBox IsChecked="{Binding AutoAcceptCertificates}"
+                                      Content="Auto-accept untrusted server certificates"
+                                      VerticalAlignment="Bottom"
+                                      Margin="0,0,0,4" />
+                        </StackPanel>
+                    </StackPanel>
+                </Expander>
+
                 <!-- Redundancy Info -->
                 <StackPanel Orientation="Horizontal"
-                            Spacing="12"
-                            IsVisible="{Binding RedundancyInfo, Converter={x:Static ObjectConverters.IsNotNull}}">
+                            Spacing="16"
+                            IsVisible="{Binding RedundancyInfo, Converter={x:Static ObjectConverters.IsNotNull}}"
+                            Margin="0,2,0,0">
                     <TextBlock Text="{Binding RedundancyInfo.Mode, StringFormat='Redundancy: {0}'}"
-                               FontSize="11" />
+                               FontSize="11" Foreground="Gray" />
                     <TextBlock Text="{Binding RedundancyInfo.ServiceLevel, StringFormat='Service Level: {0}'}"
-                               FontSize="11" />
+                               FontSize="11" Foreground="Gray" />
                     <TextBlock Text="{Binding RedundancyInfo.ApplicationUri, StringFormat='URI: {0}'}"
-                               FontSize="11" />
+                               FontSize="11" Foreground="Gray" />
                 </StackPanel>
             </StackPanel>
         </Border>
@@ -80,12 +127,10 @@
                                           Name="BrowseTreePanel">
                         <views:BrowseTreeView.ContextMenu>
                             <ContextMenu Name="TreeContextMenu">
-                                <MenuItem Header="Subscribe"
-                                          Command="{Binding $parent[Window].((vm:MainWindowViewModel)DataContext).SubscribeSelectedNodesCommand}"
-                                          IsEnabled="{Binding $parent[Window].((vm:MainWindowViewModel)DataContext).IsConnected}" />
-                                <MenuItem Header="View History"
-                                          Command="{Binding $parent[Window].((vm:MainWindowViewModel)DataContext).ViewHistoryForSelectedNodeCommand}"
-                                          IsEnabled="{Binding $parent[Window].((vm:MainWindowViewModel)DataContext).IsHistoryEnabledForSelection}" />
+                                <MenuItem Header="Subscribe" Name="SubscribeMenuItem" />
+                                <MenuItem Header="View History" Name="ViewHistoryMenuItem" />
+                                <Separator />
+                                <MenuItem Header="Monitor Alarms" Name="MonitorAlarmsMenuItem" />
                             </ContextMenu>
                         </views:BrowseTreeView.ContextMenu>
                     </views:BrowseTreeView>
@@ -102,10 +147,10 @@
                 <TabItem Header="Read/Write">
                     <views:ReadWriteView DataContext="{Binding ReadWrite}" />
                 </TabItem>
-                <TabItem Header="Subscriptions">
+                <TabItem Header="{Binding SubscriptionsTabHeader}">
                     <views:SubscriptionsView DataContext="{Binding Subscriptions}" />
                 </TabItem>
-                <TabItem Header="Alarms">
+                <TabItem Header="{Binding AlarmsTabHeader}">
                     <views:AlarmsView DataContext="{Binding Alarms}" />
                 </TabItem>
                 <TabItem Header="History">

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/MainWindow.axaml.cs

@@ -1,6 +1,9 @@
 using System.ComponentModel;
+using System.Reflection;
 using Avalonia.Controls;
 using Avalonia.Interactivity;
+using SkiaSharp;
+using Svg.Skia;
 using ZB.MOM.WW.LmxOpcUa.Client.UI.ViewModels;
 
 namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Views;
@@ -10,6 +13,41 @@ public partial class MainWindow : Window
     public MainWindow()
     {
         InitializeComponent();
+        LoadIcon();
+    }
+
+    private void LoadIcon()
+    {
+        try
+        {
+            var assembly = Assembly.GetExecutingAssembly();
+            using var stream = assembly.GetManifestResourceStream("ZB.MOM.WW.LmxOpcUa.Client.UI.Assets.app-icon.svg");
+            if (stream == null) return;
+
+            using var svg = new SKSvg();
+            svg.Load(stream);
+            if (svg.Picture == null) return;
+
+            var size = 64;
+            using var bitmap = new SKBitmap(size, size);
+            using var canvas = new SKCanvas(bitmap);
+            canvas.Clear(SKColors.Transparent);
+
+            var bounds = svg.Picture.CullRect;
+            var scale = Math.Min(size / bounds.Width, size / bounds.Height);
+            canvas.Translate((size - bounds.Width * scale) / 2, (size - bounds.Height * scale) / 2);
+            canvas.Scale(scale);
+            canvas.DrawPicture(svg.Picture);
+
+            using var image = SKImage.FromBitmap(bitmap);
+            using var data = image.Encode(SKEncodedImageFormat.Png, 100);
+            using var pngStream = new MemoryStream(data.ToArray());
+            Icon = new WindowIcon(pngStream);
+        }
+        catch
+        {
+            // Icon loading is best-effort
+        }
     }
 
     protected override void OnLoaded(RoutedEventArgs e)
@@ -20,19 +58,28 @@ public partial class MainWindow : Window
         var treeView = browseTreeView?.FindControl<TreeView>("BrowseTree");
         if (treeView != null) treeView.SelectionChanged += OnTreeSelectionChanged;
 
-        // Wire up context menu opening to sync selection and check history
         var contextMenu = this.FindControl<ContextMenu>("TreeContextMenu");
         if (contextMenu != null) contextMenu.Opening += OnTreeContextMenuOpening;
+
+        var subscribeItem = this.FindControl<MenuItem>("SubscribeMenuItem");
+        if (subscribeItem != null) subscribeItem.Click += OnSubscribeClicked;
+
+        var viewHistoryItem = this.FindControl<MenuItem>("ViewHistoryMenuItem");
+        if (viewHistoryItem != null) viewHistoryItem.Click += OnViewHistoryClicked;
+
+        var monitorAlarmsItem = this.FindControl<MenuItem>("MonitorAlarmsMenuItem");
+        if (monitorAlarmsItem != null) monitorAlarmsItem.Click += OnMonitorAlarmsClicked;
+
+        var browseCertPath = this.FindControl<Button>("BrowseCertPathButton");
+        if (browseCertPath != null) browseCertPath.Click += OnBrowseCertPathClicked;
     }
 
     private void OnTreeSelectionChanged(object? sender, SelectionChangedEventArgs e)
     {
         if (DataContext is not MainWindowViewModel vm || sender is not TreeView treeView) return;
 
-        // Update single selection for read/write and history panels
         vm.SelectedTreeNode = treeView.SelectedItem as TreeNodeViewModel;
 
-        // Sync multi-selection collection
         vm.SelectedTreeNodes.Clear();
         foreach (var item in treeView.SelectedItems)
             if (item is TreeNodeViewModel node)
@@ -41,6 +88,59 @@ public partial class MainWindow : Window
 
     private void OnTreeContextMenuOpening(object? sender, CancelEventArgs e)
     {
-        if (DataContext is MainWindowViewModel vm) vm.UpdateHistoryEnabledForSelection();
+        if (DataContext is not MainWindowViewModel vm) return;
+
+        vm.UpdateHistoryEnabledForSelection();
+
+        var subscribeItem = this.FindControl<MenuItem>("SubscribeMenuItem");
+        var viewHistoryItem = this.FindControl<MenuItem>("ViewHistoryMenuItem");
+        var monitorAlarmsItem = this.FindControl<MenuItem>("MonitorAlarmsMenuItem");
+
+        if (subscribeItem != null)
+            subscribeItem.IsEnabled = vm.IsConnected && vm.SelectedTreeNodes.Count > 0;
+        if (viewHistoryItem != null)
+            viewHistoryItem.IsEnabled = vm.IsHistoryEnabledForSelection;
+        if (monitorAlarmsItem != null)
+            monitorAlarmsItem.IsEnabled = vm.IsConnected && vm.SelectedTreeNodes.Count > 0;
     }
-}
+
+    private async void OnSubscribeClicked(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is MainWindowViewModel vm)
+            await vm.SubscribeSelectedNodesCommand.ExecuteAsync(null);
+    }
+
+    private void OnViewHistoryClicked(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is MainWindowViewModel vm)
+            vm.ViewHistoryForSelectedNodeCommand.Execute(null);
+    }
+
+    private async void OnMonitorAlarmsClicked(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is MainWindowViewModel vm)
+            await vm.MonitorAlarmsForSelectedNodeCommand.ExecuteAsync(null);
+    }
+
+    private async void OnBrowseCertPathClicked(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is not MainWindowViewModel vm) return;
+
+        var dialog = new OpenFolderDialog
+        {
+            Title = "Select Certificate Store Folder",
+            Directory = vm.CertificateStorePath
+        };
+
+        var result = await dialog.ShowAsync(this);
+        if (!string.IsNullOrEmpty(result))
+            vm.CertificateStorePath = result;
+    }
+
+    protected override void OnClosing(WindowClosingEventArgs e)
+    {
+        if (DataContext is MainWindowViewModel vm)
+            vm.SaveSettings();
+        base.OnClosing(e);
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/SubscriptionsView.axaml

@@ -16,16 +16,19 @@
         </StackPanel>
 
         <!-- Active Subscriptions List -->
-        <DataGrid ItemsSource="{Binding ActiveSubscriptions}"
+        <DataGrid Name="SubscriptionsGrid"
+                  ItemsSource="{Binding ActiveSubscriptions}"
                   SelectedItem="{Binding SelectedSubscription}"
+                  SelectionMode="Extended"
                   AutoGenerateColumns="False"
                   IsReadOnly="True"
+                  HorizontalScrollBarVisibility="Auto"
                   Margin="0,8,0,0">
             <DataGrid.Columns>
-                <DataGridTextColumn Header="Node ID" Binding="{Binding NodeId}" Width="250" />
-                <DataGridTextColumn Header="Value" Binding="{Binding Value}" Width="150" />
-                <DataGridTextColumn Header="Status" Binding="{Binding Status}" Width="120" />
-                <DataGridTextColumn Header="Timestamp" Binding="{Binding Timestamp}" Width="200" />
+                <DataGridTextColumn Header="Node ID" Binding="{Binding NodeId}" Width="Auto" />
+                <DataGridTextColumn Header="Value" Binding="{Binding Value}" Width="Auto" />
+                <DataGridTextColumn Header="Status" Binding="{Binding Status}" Width="Auto" />
+                <DataGridTextColumn Header="Timestamp" Binding="{Binding Timestamp}" Width="Auto" />
             </DataGrid.Columns>
         </DataGrid>
     </DockPanel>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/SubscriptionsView.axaml.cs

@@ -1,4 +1,8 @@
 using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+using Avalonia.VisualTree;
+using ZB.MOM.WW.LmxOpcUa.Client.UI.ViewModels;
 
 namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Views;
 
@@ -8,4 +12,40 @@ public partial class SubscriptionsView : UserControl
     {
         InitializeComponent();
     }
-}
+
+    protected override void OnLoaded(RoutedEventArgs e)
+    {
+        base.OnLoaded(e);
+
+        var grid = this.FindControl<DataGrid>("SubscriptionsGrid");
+        if (grid != null)
+        {
+            grid.DoubleTapped += OnGridDoubleTapped;
+            grid.SelectionChanged += OnGridSelectionChanged;
+        }
+    }
+
+    private void OnGridSelectionChanged(object? sender, SelectionChangedEventArgs e)
+    {
+        if (DataContext is not SubscriptionsViewModel vm || sender is not DataGrid grid) return;
+
+        vm.SelectedSubscriptions.Clear();
+        foreach (var item in grid.SelectedItems)
+            if (item is SubscriptionItemViewModel sub)
+                vm.SelectedSubscriptions.Add(sub);
+
+        vm.RemoveSubscriptionCommand.NotifyCanExecuteChanged();
+    }
+
+    private void OnGridDoubleTapped(object? sender, TappedEventArgs e)
+    {
+        if (DataContext is not SubscriptionsViewModel vm) return;
+        if (vm.SelectedSubscription is not { } item) return;
+
+        var parentWindow = this.FindAncestorOfType<Window>();
+        if (parentWindow == null) return;
+
+        var writeWindow = new WriteValueWindow(vm, item.NodeId, item.Value);
+        writeWindow.ShowDialog(parentWindow);
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/WriteValueWindow.axaml

@@ -0,0 +1,37 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:Class="ZB.MOM.WW.LmxOpcUa.Client.UI.Views.WriteValueWindow"
+        Title="Write Value"
+        Width="420"
+        SizeToContent="Height"
+        MinHeight="280"
+        WindowStartupLocation="CenterOwner"
+        CanResize="False">
+    <StackPanel Margin="16" Spacing="12">
+        <TextBlock Text="Write Value to Node" FontWeight="Bold" FontSize="16" />
+
+        <StackPanel Spacing="4">
+            <TextBlock Text="Node ID:" FontSize="12" Foreground="Gray" />
+            <TextBlock Name="NodeIdText" FontWeight="SemiBold" />
+        </StackPanel>
+
+        <StackPanel Spacing="4">
+            <TextBlock Text="Current Value:" FontSize="12" Foreground="Gray" />
+            <TextBlock Name="CurrentValueText" />
+        </StackPanel>
+
+        <StackPanel Spacing="4">
+            <TextBlock Text="New Value:" FontSize="12" Foreground="Gray" />
+            <TextBox Name="WriteValueInput" Watermark="Enter value to write" />
+        </StackPanel>
+
+        <StackPanel Spacing="4">
+            <TextBlock Name="ResultText" Foreground="Gray" />
+        </StackPanel>
+
+        <StackPanel Orientation="Horizontal" Spacing="8" HorizontalAlignment="Right">
+            <Button Name="WriteButton" Content="Write" />
+            <Button Name="CloseButton" Content="Close" />
+        </StackPanel>
+    </StackPanel>
+</Window>

src/ZB.MOM.WW.LmxOpcUa.Client.UI/Views/WriteValueWindow.axaml.cs

@@ -0,0 +1,77 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Media;
+using ZB.MOM.WW.LmxOpcUa.Client.UI.ViewModels;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.UI.Views;
+
+public partial class WriteValueWindow : Window
+{
+    private readonly SubscriptionsViewModel _subscriptionsVm;
+    private readonly string _nodeId;
+
+    public WriteValueWindow()
+    {
+        InitializeComponent();
+        _subscriptionsVm = null!;
+        _nodeId = string.Empty;
+    }
+
+    public WriteValueWindow(SubscriptionsViewModel subscriptionsVm, string nodeId, string? currentValue)
+    {
+        InitializeComponent();
+        _subscriptionsVm = subscriptionsVm;
+        _nodeId = nodeId;
+
+        var nodeIdText = this.FindControl<TextBlock>("NodeIdText");
+        if (nodeIdText != null) nodeIdText.Text = nodeId;
+
+        var currentValueText = this.FindControl<TextBlock>("CurrentValueText");
+        if (currentValueText != null) currentValueText.Text = currentValue ?? "(null)";
+
+        // Pre-fill the write input with the current value
+        var writeInput = this.FindControl<TextBox>("WriteValueInput");
+        if (writeInput != null) writeInput.Text = currentValue ?? "";
+
+        var writeButton = this.FindControl<Button>("WriteButton");
+        if (writeButton != null) writeButton.Click += OnWriteClicked;
+
+        var closeButton = this.FindControl<Button>("CloseButton");
+        if (closeButton != null) closeButton.Click += OnCloseClicked;
+    }
+
+    private async void OnWriteClicked(object? sender, RoutedEventArgs e)
+    {
+        var input = this.FindControl<TextBox>("WriteValueInput");
+        var resultText = this.FindControl<TextBlock>("ResultText");
+        if (input == null || resultText == null) return;
+
+        var rawValue = input.Text;
+        if (string.IsNullOrEmpty(rawValue))
+        {
+            resultText.Foreground = Brushes.Red;
+            resultText.Text = "Please enter a value.";
+            return;
+        }
+
+        resultText.Foreground = Brushes.Gray;
+        resultText.Text = "Writing...";
+
+        var (success, message) = await _subscriptionsVm.ValidateAndWriteAsync(_nodeId, rawValue);
+
+        if (success)
+        {
+            Close();
+        }
+        else
+        {
+            resultText.Foreground = Brushes.Red;
+            resultText.Text = message;
+        }
+    }
+
+    private void OnCloseClicked(object? sender, RoutedEventArgs e)
+    {
+        Close();
+    }
+}

src/ZB.MOM.WW.LmxOpcUa.Client.UI/ZB.MOM.WW.LmxOpcUa.Client.UI.csproj

@@ -11,9 +11,11 @@
     <ItemGroup>
         <PackageReference Include="Avalonia" Version="11.2.7"/>
         <PackageReference Include="Avalonia.Desktop" Version="11.2.7"/>
+        <PackageReference Include="Avalonia.Svg.Skia" Version="11.2.0.2"/>
         <PackageReference Include="Avalonia.Themes.Fluent" Version="11.2.7"/>
         <PackageReference Include="Avalonia.Fonts.Inter" Version="11.2.7"/>
         <PackageReference Include="Avalonia.Controls.DataGrid" Version="11.2.7"/>
+        <PackageReference Include="Avalonia.Diagnostics" Version="11.2.7"/>
         <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.0"/>
         <PackageReference Include="Serilog" Version="4.2.0"/>
         <PackageReference Include="Serilog.Sinks.Console" Version="6.0.0"/>
@@ -27,4 +29,9 @@
         <InternalsVisibleTo Include="ZB.MOM.WW.LmxOpcUa.Client.UI.Tests"/>
     </ItemGroup>
 
+    <ItemGroup>
+        <AvaloniaResource Include="Assets\**" Exclude="Assets\app-icon.svg" />
+        <EmbeddedResource Include="Assets\app-icon.svg" />
+    </ItemGroup>
+
 </Project>

src/ZB.MOM.WW.LmxOpcUa.Host/Historian/HistorianDataSource.cs

@@ -42,8 +42,8 @@ namespace ZB.MOM.WW.LmxOpcUa.Host.Historian
         {
             var results = new List<DataValue>();
             var sql = maxValues > 0
-                ? "SELECT TOP (@MaxValues) DateTime, Value, vValue, Quality FROM Runtime.dbo.History WHERE TagName = @TagName AND DateTime >= @StartTime AND DateTime <= @EndTime ORDER BY DateTime"
-                : "SELECT DateTime, Value, vValue, Quality FROM Runtime.dbo.History WHERE TagName = @TagName AND DateTime >= @StartTime AND DateTime <= @EndTime ORDER BY DateTime";
+                ? "SELECT TOP (@MaxValues) DateTime, Value, vValue, OPCQuality FROM Runtime.dbo.History WHERE TagName = @TagName AND wwTimezone='UTC' AND DateTime >= @StartTime AND DateTime <= @EndTime ORDER BY DateTime"
+                : "SELECT DateTime, Value, vValue, OPCQuality FROM Runtime.dbo.History WHERE TagName = @TagName AND wwTimezone='UTC' AND DateTime >= @StartTime AND DateTime <= @EndTime ORDER BY DateTime";
 
             using var conn = new SqlConnection(_config.ConnectionString);
             await conn.OpenAsync(ct);
@@ -58,7 +58,7 @@ namespace ZB.MOM.WW.LmxOpcUa.Host.Historian
             using var reader = await cmd.ExecuteReaderAsync(ct);
             while (await reader.ReadAsync(ct))
             {
-                var timestamp = reader.GetDateTime(0);
+                var timestamp = DateTime.SpecifyKind(reader.GetDateTime(0), DateTimeKind.Utc);
                 object? value;
                 if (!reader.IsDBNull(1))
                     value = reader.GetDouble(1);
@@ -99,7 +99,7 @@ namespace ZB.MOM.WW.LmxOpcUa.Host.Historian
         {
             var results = new List<DataValue>();
             var sql = $"SELECT StartDateTime, [{aggregateColumn}] FROM Runtime.dbo.AnalogSummaryHistory " +
-                      "WHERE TagName = @TagName AND StartDateTime >= @StartTime AND StartDateTime <= @EndTime " +
+                      "WHERE TagName = @TagName AND wwTimezone='UTC' AND StartDateTime >= @StartTime AND StartDateTime <= @EndTime " +
                       "AND wwResolution = @Resolution ORDER BY StartDateTime";
 
             using var conn = new SqlConnection(_config.ConnectionString);
@@ -114,7 +114,7 @@ namespace ZB.MOM.WW.LmxOpcUa.Host.Historian
             using var reader = await cmd.ExecuteReaderAsync(ct);
             while (await reader.ReadAsync(ct))
             {
-                var timestamp = reader.GetDateTime(0);
+                var timestamp = DateTime.SpecifyKind(reader.GetDateTime(0), DateTimeKind.Utc);
                 var value = reader.IsDBNull(1) ? (object?)null : reader.GetDouble(1);
 
                 results.Add(new DataValue

src/ZB.MOM.WW.LmxOpcUa.Host/OpcUa/LmxNodeManager.cs

@@ -1100,6 +1100,11 @@ namespace ZB.MOM.WW.LmxOpcUa.Host.OpcUa
             ///     Gets or sets the Galaxy tag reference for the acknowledge message that triggers acknowledgment.
             /// </summary>
             public string AckMsgTagReference { get; set; } = "";
+
+            /// <summary>
+            ///     Gets or sets the most recent acknowledged state so duplicate transitions are not reissued.
+            /// </summary>
+            public bool? LastAcked { get; set; }
         }
 
         #region Read/Write Handlers
@@ -1726,13 +1731,15 @@ namespace ZB.MOM.WW.LmxOpcUa.Host.OpcUa
                                     alarmInfo = null;
                             }
 
-                            // Check for Acked transitions
+                            // Check for Acked transitions — skip if state hasn't changed
                             if (_alarmAckedTags.TryGetValue(address, out ackedAlarmInfo))
                             {
                                 newAcked = vtq.Value is true || vtq.Value is 1 ||
                                            (vtq.Value is int ackedIntVal && ackedIntVal != 0);
-                                pendingAckedEvents.Add((ackedAlarmInfo, newAcked));
-                                ackedAlarmInfo = null; // handled
+                                if (ackedAlarmInfo.LastAcked.HasValue && newAcked == ackedAlarmInfo.LastAcked.Value)
+                                    ackedAlarmInfo = null; // No transition → skip
+                                else
+                                    pendingAckedEvents.Add((ackedAlarmInfo, newAcked));
                             }
                         }
 
@@ -1818,6 +1825,12 @@ namespace ZB.MOM.WW.LmxOpcUa.Host.OpcUa
                             // Apply Acked state changes
                             foreach (var (info, acked) in pendingAckedEvents)
                             {
+                                // Double-check dedup under lock
+                                if (info.LastAcked.HasValue && acked == info.LastAcked.Value)
+                                    continue;
+
+                                info.LastAcked = acked;
+
                                 var condition = info.ConditionNode;
                                 if (condition == null) continue;