Snapshot the v5 hosts screen mid-restructure, with handoff notes to resume it

src/DodoSSH.Client.App/Views/MonogramBrushConverter.cs

@@ -0,0 +1,54 @@
+using System.Globalization;
+using Avalonia.Data.Converters;
+using Avalonia.Media;
+
+namespace DodoSSH.Client.App.Views;
+
+/// <summary>
+/// Turns a host card's <c>MonogramHue</c> string into the background or foreground brush the mock pairs it
+/// with.
+/// </summary>
+/// <remarks>
+/// <para>
+/// The four pairs are the design's own and are not in <c>Palette.axaml</c>: that file is another wave's, and
+/// none of the shared palette's existing keys is this hue ramp — a monogram's colour is a property of the
+/// four-way hash in <c>HostRowViewModel.MonogramHue</c>, not a fact the rest of the theme has any use for.
+/// Held here, beside the one screen that reads it, rather than invented as four new shared resources for a
+/// single card.
+/// </para>
+/// <para>
+/// Two instances rather than one converter taking a "which half" parameter, so the markup names each with a
+/// <c>StaticResource</c>-shaped reference instead of a converter parameter that means nothing without
+/// reading this file.
+/// </para>
+/// </remarks>
+internal sealed class MonogramBrushConverter(bool background) : IValueConverter
+{
+    /// <summary>The fill behind the two letters.</summary>
+    internal static MonogramBrushConverter Background { get; } = new(background: true);
+
+    /// <summary>The colour of the two letters themselves.</summary>
+    internal static MonogramBrushConverter Foreground { get; } = new(background: false);
+
+    /// <summary>violet, green, amber, gray — the four pairs the mock assigns a monogram.</summary>
+    private static readonly Dictionary<string, (string Background, string Foreground)> Pairs = new(
+        StringComparer.Ordinal)
+    {
+        ["violet"] = ("#241C4F", "#A78BFA"),
+        ["green"] = ("#103A2F", "#34D399"),
+        ["amber"] = ("#423211", "#F5B942"),
+        ["gray"] = ("#1E1E2C", "#9C9EB4"),
+    };
+
+    /// <inheritdoc />
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        var pair = value is string hue && Pairs.TryGetValue(hue, out var found) ? found : Pairs["gray"];
+
+        return new SolidColorBrush(Color.Parse(background ? pair.Background : pair.Foreground));
+    }
+
+    /// <inheritdoc />
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture) =>
+        throw new NotSupportedException("The monogram hue is read-only.");
+}