Reject non-finite range values

Lessons.md

@@ -22,6 +22,7 @@
 - Treat screenshot-reported UI precision bugs as shared geometry suspects first. Hit testing, caret placement, slider bounds, and popup placement usually belong in shared measurement, transform, bounds, or z-layer code rather than one-off component fixes.
 - Keep the UI A/B sample useful as a validation tool, not just a showcase. Add visible state, labels, and layout previews when controls otherwise look inert or ambiguous.
 - For retained text input, caret, selection, and scrolling should share measured text advances. Any fallback heuristic must be treated as a temporary approximation and tested against proportional text.
+- Numeric UI controls should reject non-finite `Minimum`, `Maximum`, `Value`, and step values before clamping or render math runs. Letting `NaN` or infinities enter range state can poison slider/progress geometry.
 - For retained UI controls that render text with measured glyph widths, auto-size measurement should use the same measured text path. Character-count heuristics are only safe as fallbacks when no render measurement context is available.
 
 ## PR Review And Triage

src/ModernOverlay.UI/AdvancedControls.cs

@@ -54,6 +54,7 @@ public double Minimum
         get => minimum;
         set
         {
+            ValidateFinite(value, nameof(value));
             minimum = value;
             if (maximum < minimum)
             {
@@ -72,6 +73,7 @@ public double Maximum
         get => maximum;
         set
         {
+            ValidateFinite(value, nameof(value));
             maximum = Math.Max(value, Minimum);
             Value = this.value;
         }
@@ -102,6 +104,7 @@ public double Value
         get => value;
         set
         {
+            ValidateFinite(value, nameof(value));
             double next = Math.Clamp(value, Minimum, Maximum);
             if (this.value.Equals(next))
             {
@@ -185,6 +188,14 @@ private void RevertText()
 
     private static bool IsPartialNumberText(string text)
         => text.Length == 0 || text is "-" or "+" or "." or "-." or "+.";
+
+    private static void ValidateFinite(double value, string parameterName)
+    {
+        if (!double.IsFinite(value))
+        {
+            throw new ArgumentOutOfRangeException(parameterName, "Numeric values must be finite.");
+        }
+    }
 }
 
 /// <summary>

src/ModernOverlay.UI/Controls.cs

@@ -994,6 +994,7 @@ public float Minimum
         get => minimum;
         set
         {
+            ValidateFinite(value, nameof(value));
             SetProperty(ref minimum, value, UiInvalidation.Render);
             if (maximum < minimum)
             {
@@ -1012,6 +1013,7 @@ public float Maximum
         get => maximum;
         set
         {
+            ValidateFinite(value, nameof(value));
             SetProperty(ref maximum, MathF.Max(value, minimum), UiInvalidation.Render);
             Value = this.value;
         }
@@ -1025,6 +1027,7 @@ public float Value
         get => value;
         set
         {
+            ValidateFinite(value, nameof(value));
             if (SetProperty(ref this.value, Math.Clamp(value, Minimum, Maximum), UiInvalidation.Render))
             {
                 ValueChanged?.Invoke(this, EventArgs.Empty);
@@ -1076,6 +1079,14 @@ protected float ValueRatio
     }
 
     protected void ChangeValueBy(float delta) => Value += delta;
+
+    private static void ValidateFinite(float value, string parameterName)
+    {
+        if (!float.IsFinite(value))
+        {
+            throw new ArgumentOutOfRangeException(parameterName, "Range values must be finite.");
+        }
+    }
 }
 
 /// <summary>

tests/ModernOverlay.Tests/OverlayUiRangeNumericTests.cs

@@ -136,6 +136,22 @@ public async Task NumberBoxParsesInvariantTextRejectsInvalidInputAndUsesStepButt
         }
     }
 
+    [TestMethod]
+    public void RangeControlsRejectNonFiniteNumericValues()
+    {
+        Slider slider = new();
+
+        Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => slider.Minimum = float.NaN);
+        Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => slider.Maximum = float.PositiveInfinity);
+        Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => slider.Value = float.NegativeInfinity);
+
+        NumberBox number = new();
+
+        Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => number.Minimum = double.NaN);
+        Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => number.Maximum = double.PositiveInfinity);
+        Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => number.Value = double.NegativeInfinity);
+    }
+
     private static async ValueTask<OverlayWindow> CreateOverlayAsync()
         => await OverlayWindow.CreateAsync(new OverlayWindowOptions
         {