fix: resolve CodeQL complex-condition alert and PerformanceView MVVM violation

CHANGELOG.md

@@ -7,11 +7,23 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 ## [Unreleased]
 
 ### Fixed
+- **ProcessManagerViewModel** — resolved CodeQL `cs/complex-condition` alert (#302)
+  by replacing chained null-conditional `||` expression with a `ReadOnlySpan` loop
+  in `MatchesDescription`.
+- **PerformanceView** — eliminated MVVM violation: removed `PropertyChanged`
+  subscription and `Checked` event handler from code-behind; radio buttons now use
+  two-way `EqualityConverter` binding to `SelectedPlan` (pure XAML, no code-behind
+  logic).
 - **OperationLockServiceTests** — replaced flaky `Barrier` + `Thread.Sleep`
   thread-safety test with deterministic `CountdownEvent` + `ManualResetEventSlim`
   synchronization; asserts exactly 1 acquisition instead of `>= 1`.
 
 ### Added
+- **EqualityConverter** — reusable two-way `IValueConverter` that compares a bound
+  value to `ConverterParameter`; ideal for radio button groups bound to a string
+  property.
+- **EqualityConverterTests** — 10 unit tests covering Convert/ConvertBack, null
+  handling, and case sensitivity.
 - **FormatHelperTests** — 14 unit tests covering `FormatSize` at all boundaries
   (bytes, KB, MB, GB) with exact boundary and mid-range values.
 

SysManager/SysManager.Tests/EqualityConverterTests.cs

@@ -0,0 +1,82 @@
+// SysManager · EqualityConverterTests
+// Author: laurentiu021 · https://github.com/laurentiu021/SystemManager
+// License: MIT
+
+using System.Globalization;
+using System.Windows.Data;
+using SysManager.Helpers;
+
+namespace SysManager.Tests;
+
+/// <summary>
+/// Tests for <see cref="EqualityConverter"/>.
+/// </summary>
+public class EqualityConverterTests
+{
+    private readonly EqualityConverter _sut = new();
+
+    [Theory]
+    [InlineData("balanced", "balanced", true)]
+    [InlineData("high", "high", true)]
+    [InlineData("ultimate", "ultimate", true)]
+    [InlineData("balanced", "high", false)]
+    [InlineData("high", "ultimate", false)]
+    [InlineData("", "balanced", false)]
+    public void Convert_ComparesValueToParameter(string value, string parameter, bool expected)
+    {
+        var result = _sut.Convert(value, typeof(bool), parameter, CultureInfo.InvariantCulture);
+        Assert.Equal(expected, result);
+    }
+
+    [Fact]
+    public void Convert_NullValue_ReturnsFalse()
+    {
+        var result = _sut.Convert(null, typeof(bool), "balanced", CultureInfo.InvariantCulture);
+        Assert.Equal(false, result);
+    }
+
+    [Fact]
+    public void Convert_NullParameter_ReturnsFalse()
+    {
+        var result = _sut.Convert("balanced", typeof(bool), null, CultureInfo.InvariantCulture);
+        Assert.Equal(false, result);
+    }
+
+    [Fact]
+    public void Convert_BothNull_ReturnsFalse()
+    {
+        var result = _sut.Convert(null, typeof(bool), null, CultureInfo.InvariantCulture);
+        Assert.Equal(false, result);
+    }
+
+    [Theory]
+    [InlineData("balanced")]
+    [InlineData("high")]
+    [InlineData("ultimate")]
+    public void ConvertBack_WhenTrue_ReturnsParameter(string parameter)
+    {
+        var result = _sut.ConvertBack(true, typeof(string), parameter, CultureInfo.InvariantCulture);
+        Assert.Equal(parameter, result);
+    }
+
+    [Fact]
+    public void ConvertBack_WhenFalse_ReturnsDoNothing()
+    {
+        var result = _sut.ConvertBack(false, typeof(string), "balanced", CultureInfo.InvariantCulture);
+        Assert.Equal(Binding.DoNothing, result);
+    }
+
+    [Fact]
+    public void ConvertBack_WhenNull_ReturnsDoNothing()
+    {
+        var result = _sut.ConvertBack(null, typeof(string), "balanced", CultureInfo.InvariantCulture);
+        Assert.Equal(Binding.DoNothing, result);
+    }
+
+    [Fact]
+    public void Convert_IsCaseSensitive()
+    {
+        var result = _sut.Convert("Balanced", typeof(bool), "balanced", CultureInfo.InvariantCulture);
+        Assert.Equal(false, result);
+    }
+}

SysManager/SysManager/App.xaml

@@ -22,6 +22,7 @@
             <h:OutputKindToBrushConverter x:Key="KindBrush"/>
             <h:ProcessStatusToBrushConverter x:Key="StatusBrush"/>
             <h:IntGreaterThanZeroConverter x:Key="GreaterThanZero"/>
+            <h:EqualityConverter x:Key="IsEqual"/>
 
             <sys:Boolean xmlns:sys="clr-namespace:System;assembly=mscorlib" x:Key="TrueValue">True</sys:Boolean>
             <sys:Boolean xmlns:sys="clr-namespace:System;assembly=mscorlib" x:Key="FalseValue">False</sys:Boolean>

SysManager/SysManager/Helpers/EqualityConverter.cs

@@ -0,0 +1,31 @@
+// SysManager · EqualityConverter — two-way value equality for radio buttons
+// Author: laurentiu021 · https://github.com/laurentiu021/SystemManager
+// License: MIT
+
+using System.Globalization;
+using System.Windows.Data;
+
+namespace SysManager.Helpers;
+
+/// <summary>
+/// Two-way converter that compares a bound value to ConverterParameter.
+/// Convert: returns true when value equals parameter (for IsChecked).
+/// ConvertBack: returns the parameter when IsChecked becomes true.
+/// Usage: IsChecked="{Binding SelectedPlan, Converter={StaticResource IsEqual}, ConverterParameter=balanced}"
+/// </summary>
+public sealed class EqualityConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        if (value == null || parameter == null)
+            return false;
+        return string.Equals(value.ToString(), parameter.ToString(), StringComparison.Ordinal);
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        if (value is true)
+            return parameter?.ToString();
+        return Binding.DoNothing;
+    }
+}

SysManager/SysManager/ViewModels/ProcessManagerViewModel.cs

@@ -165,10 +165,16 @@ private static bool MatchesFilter(ProcessEntry p, string filter) =>
     private static bool MatchesName(ProcessEntry p, string filter) =>
         p.Name.Contains(filter, StringComparison.OrdinalIgnoreCase);
 
-    private static bool MatchesDescription(ProcessEntry p, string filter) =>
-        (p.Description?.Contains(filter, StringComparison.OrdinalIgnoreCase) ?? false) ||
-        (p.PlainDescription?.Contains(filter, StringComparison.OrdinalIgnoreCase) ?? false) ||
-        (p.Category?.Contains(filter, StringComparison.OrdinalIgnoreCase) ?? false);
+    private static bool MatchesDescription(ProcessEntry p, string filter)
+    {
+        ReadOnlySpan<string?> fields = [p.Description, p.PlainDescription, p.Category];
+        foreach (var field in fields)
+        {
+            if (field?.Contains(filter, StringComparison.OrdinalIgnoreCase) == true)
+                return true;
+        }
+        return false;
+    }
 
     private static bool MatchesPid(ProcessEntry p, string filter) =>
         p.Pid.ToString().Contains(filter);

SysManager/SysManager/Views/PerformanceView.xaml

@@ -61,15 +61,15 @@
                             <RadioButton x:Name="RbBalanced"
                                          Content="Balanced (default — recommended for laptops)"
                                          GroupName="PowerPlan" Margin="0,0,0,8"
-                                         Tag="balanced" Checked="PowerPlan_Checked"/>
+                                         IsChecked="{Binding SelectedPlan, Converter={StaticResource IsEqual}, ConverterParameter=balanced}"/>
                             <RadioButton x:Name="RbHigh"
                                          Content="High Performance"
                                          GroupName="PowerPlan" Margin="0,0,0,8"
-                                         Tag="high" Checked="PowerPlan_Checked"/>
+                                         IsChecked="{Binding SelectedPlan, Converter={StaticResource IsEqual}, ConverterParameter=high}"/>
                             <RadioButton x:Name="RbUltimate"
                                          Content="Ultimate Performance (max clocks, no throttling)"
                                          GroupName="PowerPlan" Margin="0,0,0,12"
-                                         Tag="ultimate" Checked="PowerPlan_Checked"/>
+                                         IsChecked="{Binding SelectedPlan, Converter={StaticResource IsEqual}, ConverterParameter=ultimate}"/>
                             <Button Content="Apply Power Plan" Command="{Binding ApplyPowerPlanCommand}"
                                     Style="{StaticResource SecondaryButton}" HorizontalAlignment="Left"/>
                         </StackPanel>

SysManager/SysManager/Views/PerformanceView.xaml.cs

@@ -2,55 +2,14 @@
 // Author: laurentiu021 · https://github.com/laurentiu021/SystemManager
 // License: MIT
 
-using System.Windows;
 using System.Windows.Controls;
-using SysManager.ViewModels;
 
 namespace SysManager.Views;
 
 public partial class PerformanceView : UserControl
 {
-    private System.ComponentModel.PropertyChangedEventHandler? _propertyHandler;
-
     public PerformanceView()
     {
         InitializeComponent();
-        DataContextChanged += OnDataContextChanged;
-    }
-
-    private void OnDataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
-    {
-        // MEM-004: unsubscribe from previous VM to prevent leak
-        if (e.OldValue is PerformanceViewModel oldVm && _propertyHandler != null)
-            oldVm.PropertyChanged -= _propertyHandler;
-
-        if (e.NewValue is PerformanceViewModel vm)
-        {
-            _propertyHandler = (_, args) =>
-            {
-                if (args.PropertyName == nameof(PerformanceViewModel.SelectedPlan))
-                    SyncRadioButtons(vm.SelectedPlan);
-            };
-            vm.PropertyChanged += _propertyHandler;
-            SyncRadioButtons(vm.SelectedPlan);
-        }
-    }
-
-    private void SyncRadioButtons(string plan)
-    {
-        if (!Dispatcher.CheckAccess())
-        {
-            Dispatcher.BeginInvoke(() => SyncRadioButtons(plan));
-            return;
-        }
-        RbBalanced.IsChecked = plan == "balanced";
-        RbHigh.IsChecked = plan == "high";
-        RbUltimate.IsChecked = plan == "ultimate";
-    }
-
-    private void PowerPlan_Checked(object sender, RoutedEventArgs e)
-    {
-        if (sender is RadioButton rb && DataContext is PerformanceViewModel vm)
-            vm.SelectedPlan = rb.Tag?.ToString() ?? "balanced";
     }
 }