perf(themes): add pre-computed ABGR cache on theme records

HellionChat/Themes/Theme.cs

@@ -1,3 +1,5 @@
+using HellionChat.Util;
+
 namespace HellionChat.Themes;
 
 public sealed record Theme(
@@ -10,4 +12,47 @@ public sealed record Theme(
     ThemeTypography Typography,
     bool IsBuiltIn,
     ThemeChatColors? ChatColors = null
+)
+{
+    // Pre-computed ABGR mirror of ThemeColors so PushGlobal can skip the
+    // RgbaToAbgr conversion per slot per frame.
+    public ThemeAbgrCache AbgrCache { get; private set; }
+
+    public void RecomputeAbgrCache()
+    {
+        AbgrCache = new ThemeAbgrCache(
+            PrimaryDark:   ColourUtil.RgbaToAbgr(Colors.PrimaryDark),
+            Primary:       ColourUtil.RgbaToAbgr(Colors.Primary),
+            PrimaryLight:  ColourUtil.RgbaToAbgr(Colors.PrimaryLight),
+            PrimaryGlow:   ColourUtil.RgbaToAbgr(Colors.PrimaryGlow),
+            AccentDark:    ColourUtil.RgbaToAbgr(Colors.AccentDark),
+            Accent:        ColourUtil.RgbaToAbgr(Colors.Accent),
+            AccentLight:   ColourUtil.RgbaToAbgr(Colors.AccentLight),
+            Identity:      ColourUtil.RgbaToAbgr(Colors.Identity),
+            WindowBg:      ColourUtil.RgbaToAbgr(Colors.WindowBg),
+            ChildBg:       ColourUtil.RgbaToAbgr(Colors.ChildBg),
+            FrameBg:       ColourUtil.RgbaToAbgr(Colors.FrameBg),
+            Surface:       ColourUtil.RgbaToAbgr(Colors.Surface),
+            SurfaceHover:  ColourUtil.RgbaToAbgr(Colors.SurfaceHover),
+            Border:        ColourUtil.RgbaToAbgr(Colors.Border),
+            TextPrimary:   ColourUtil.RgbaToAbgr(Colors.TextPrimary),
+            TextMuted:     ColourUtil.RgbaToAbgr(Colors.TextMuted),
+            TextDim:       ColourUtil.RgbaToAbgr(Colors.TextDim),
+            StatusSuccess: ColourUtil.RgbaToAbgr(Colors.StatusSuccess),
+            StatusDanger:  ColourUtil.RgbaToAbgr(Colors.StatusDanger),
+            StatusWarning: ColourUtil.RgbaToAbgr(Colors.StatusWarning),
+            StatusInfo:    ColourUtil.RgbaToAbgr(Colors.StatusInfo));
+    }
+}
+
+// Mirrors ThemeColors slot-for-slot. The FillsAll21Slots test pins the
+// contract — a new slot without its mirror fails the build.
+public readonly record struct ThemeAbgrCache(
+    uint PrimaryDark, uint Primary, uint PrimaryLight, uint PrimaryGlow,
+    uint AccentDark, uint Accent, uint AccentLight,
+    uint Identity,
+    uint WindowBg, uint ChildBg, uint FrameBg,
+    uint Surface, uint SurfaceHover, uint Border,
+    uint TextPrimary, uint TextMuted, uint TextDim,
+    uint StatusSuccess, uint StatusDanger, uint StatusWarning, uint StatusInfo
 );

HellionChat/Themes/ThemeRegistry.cs

@@ -25,6 +25,11 @@ public sealed class ThemeRegistry
             { ForgeMerchantman.Slug,  ForgeMerchantman.Build() },
             { MintGrove.Slug,         MintGrove.Build() },
         };
+
+        // Centralised so the nine .Build() factories stay free of cache plumbing.
+        foreach (var theme in _builtIns.Values)
+            theme.RecomputeAbgrCache();
+
         _active = _builtIns[DefaultSlug];
         _customThemesDir = customThemesDir;
     }
@@ -81,6 +86,7 @@ public sealed class ThemeRegistry
                 try
                 {
                     theme = ThemeJsonLoader.LoadFromFile(path);
+                    theme.RecomputeAbgrCache();
                     _customCache[key] = (theme, stamp);
                 }
                 catch (Exception ex)