feat(themes): default-fill missing colour/layout slots on theme load

HellionChat/Themes/ThemeJsonLoader.cs

@@ -1,5 +1,7 @@
 using System.Text.Json;
+using HellionChat.Themes.Builtin;
 using HellionChat.Util;
+using Microsoft.Extensions.Logging;
 
 namespace HellionChat.Themes;
 
@@ -11,7 +13,8 @@ internal static class ThemeJsonLoader
     // policy from the v2.x style refactor: v1 user themes are not migrated,
     // they're silently ignored so the loader stays free of legacy mapping
     // code. Any other malformed input still throws FormatException.
-    public static Theme? LoadFromString(string json)
+    // B4b-2: callers must pass the logger or the default-fill warnings go silent.
+    public static Theme? LoadFromString(string json, ILogger? logger = null)
     {
         if (string.IsNullOrWhiteSpace(json))
             throw new FormatException("Theme JSON is empty");
@@ -43,8 +46,22 @@ internal static class ThemeJsonLoader
             var author = ReadString(root, "author");
             var description = ReadString(root, "description");
 
-            var colors = ReadColors(root.GetProperty("colors"));
+            // Missing colours/layout object stays fatal, but as FormatException so the
-            var layout = ReadLayout(root.GetProperty("layout"));
+            // import path catches it — GetProperty's KeyNotFoundException would crash.
+            if (
+                !root.TryGetProperty("colors", out var colorsEl)
+                || colorsEl.ValueKind != JsonValueKind.Object
+            )
+                throw new FormatException("Theme JSON missing 'colors' object");
+            if (
+                !root.TryGetProperty("layout", out var layoutEl)
+                || layoutEl.ValueKind != JsonValueKind.Object
+            )
+                throw new FormatException("Theme JSON missing 'layout' object");
+
+            var fallback = HellionArctic.Build();
+            var colors = ReadColors(colorsEl, fallback.Colors, logger);
+            var layout = ReadLayout(layoutEl, fallback.Layout, logger);
             var typography = ReadTypography(root);
 
             ThemeChatColors? chatColors = null;
@@ -93,52 +110,72 @@ internal static class ThemeJsonLoader
         return new ThemeChatColors(dict);
     }
 
-    public static Theme? LoadFromFile(string path)
+    public static Theme? LoadFromFile(string path, ILogger? logger = null)
     {
         // FileShare.Read lets concurrent readers and well-behaved editors share
         // the handle; atomic-replace editors still raise IOException, caught upstream.
         using var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
         using var reader = new StreamReader(stream);
         var json = reader.ReadToEnd();
-        return LoadFromString(json);
+        return LoadFromString(json, logger);
     }
 
-    private static ThemeColors ReadColors(JsonElement el) =>
+    private static ThemeColors ReadColors(JsonElement el, ThemeColors fallback, ILogger? logger) =>
         new(
-            PrimaryDark: ColourUtil.HexToRgba(ReadString(el, "primaryDark")),
+            PrimaryDark: ReadColorOrDefault(el, "primaryDark", fallback.PrimaryDark, logger),
-            Primary: ColourUtil.HexToRgba(ReadString(el, "primary")),
+            Primary: ReadColorOrDefault(el, "primary", fallback.Primary, logger),
-            PrimaryLight: ColourUtil.HexToRgba(ReadString(el, "primaryLight")),
+            PrimaryLight: ReadColorOrDefault(el, "primaryLight", fallback.PrimaryLight, logger),
-            PrimaryGlow: ColourUtil.HexToRgba(ReadString(el, "primaryGlow")),
+            PrimaryGlow: ReadColorOrDefault(el, "primaryGlow", fallback.PrimaryGlow, logger),
-            AccentDark: ColourUtil.HexToRgba(ReadString(el, "accentDark")),
+            AccentDark: ReadColorOrDefault(el, "accentDark", fallback.AccentDark, logger),
-            Accent: ColourUtil.HexToRgba(ReadString(el, "accent")),
+            Accent: ReadColorOrDefault(el, "accent", fallback.Accent, logger),
-            AccentLight: ColourUtil.HexToRgba(ReadString(el, "accentLight")),
+            AccentLight: ReadColorOrDefault(el, "accentLight", fallback.AccentLight, logger),
-            Identity: ColourUtil.HexToRgba(ReadString(el, "identity")),
+            Identity: ReadColorOrDefault(el, "identity", fallback.Identity, logger),
-            WindowBg: ColourUtil.HexToRgba(ReadString(el, "windowBg")),
+            WindowBg: ReadColorOrDefault(el, "windowBg", fallback.WindowBg, logger),
-            ChildBg: ColourUtil.HexToRgba(ReadString(el, "childBg")),
+            ChildBg: ReadColorOrDefault(el, "childBg", fallback.ChildBg, logger),
-            FrameBg: ColourUtil.HexToRgba(ReadString(el, "frameBg")),
+            FrameBg: ReadColorOrDefault(el, "frameBg", fallback.FrameBg, logger),
-            Surface: ColourUtil.HexToRgba(ReadString(el, "surface")),
+            Surface: ReadColorOrDefault(el, "surface", fallback.Surface, logger),
-            SurfaceHover: ColourUtil.HexToRgba(ReadString(el, "surfaceHover")),
+            SurfaceHover: ReadColorOrDefault(el, "surfaceHover", fallback.SurfaceHover, logger),
-            Border: ColourUtil.HexToRgba(ReadString(el, "border")),
+            Border: ReadColorOrDefault(el, "border", fallback.Border, logger),
-            TextPrimary: ColourUtil.HexToRgba(ReadString(el, "textPrimary")),
+            TextPrimary: ReadColorOrDefault(el, "textPrimary", fallback.TextPrimary, logger),
-            TextMuted: ColourUtil.HexToRgba(ReadString(el, "textMuted")),
+            TextMuted: ReadColorOrDefault(el, "textMuted", fallback.TextMuted, logger),
-            TextDim: ColourUtil.HexToRgba(ReadString(el, "textDim")),
+            TextDim: ReadColorOrDefault(el, "textDim", fallback.TextDim, logger),
-            StatusSuccess: ColourUtil.HexToRgba(ReadString(el, "statusSuccess")),
+            StatusSuccess: ReadColorOrDefault(el, "statusSuccess", fallback.StatusSuccess, logger),
-            StatusDanger: ColourUtil.HexToRgba(ReadString(el, "statusDanger")),
+            StatusDanger: ReadColorOrDefault(el, "statusDanger", fallback.StatusDanger, logger),
-            StatusWarning: ColourUtil.HexToRgba(ReadString(el, "statusWarning")),
+            StatusWarning: ReadColorOrDefault(el, "statusWarning", fallback.StatusWarning, logger),
-            StatusInfo: ColourUtil.HexToRgba(ReadString(el, "statusInfo"))
+            StatusInfo: ReadColorOrDefault(el, "statusInfo", fallback.StatusInfo, logger)
         );
 
-    private static ThemeLayout ReadLayout(JsonElement el) =>
+    private static ThemeLayout ReadLayout(JsonElement el, ThemeLayout fallback, ILogger? logger) =>
         new(
-            WindowRounding: ReadFloat(el, "windowRounding"),
+            WindowRounding: ReadFloatOrDefault(
-            ChildRounding: ReadFloat(el, "childRounding"),
+                el,
-            PopupRounding: ReadFloat(el, "popupRounding"),
+                "windowRounding",
-            FrameRounding: ReadFloat(el, "frameRounding"),
+                fallback.WindowRounding,
-            GrabRounding: ReadFloat(el, "grabRounding"),
+                logger
-            TabRounding: ReadFloat(el, "tabRounding"),
+            ),
-            ScrollbarRounding: ReadFloat(el, "scrollbarRounding"),
+            ChildRounding: ReadFloatOrDefault(el, "childRounding", fallback.ChildRounding, logger),
-            WindowBorderSize: ReadFloat(el, "windowBorderSize"),
+            PopupRounding: ReadFloatOrDefault(el, "popupRounding", fallback.PopupRounding, logger),
-            FrameBorderSize: ReadFloat(el, "frameBorderSize")
+            FrameRounding: ReadFloatOrDefault(el, "frameRounding", fallback.FrameRounding, logger),
+            GrabRounding: ReadFloatOrDefault(el, "grabRounding", fallback.GrabRounding, logger),
+            TabRounding: ReadFloatOrDefault(el, "tabRounding", fallback.TabRounding, logger),
+            ScrollbarRounding: ReadFloatOrDefault(
+                el,
+                "scrollbarRounding",
+                fallback.ScrollbarRounding,
+                logger
+            ),
+            WindowBorderSize: ReadFloatOrDefault(
+                el,
+                "windowBorderSize",
+                fallback.WindowBorderSize,
+                logger
+            ),
+            FrameBorderSize: ReadFloatOrDefault(
+                el,
+                "frameBorderSize",
+                fallback.FrameBorderSize,
+                logger
+            )
         );
 
     // Optional in v2 — themes without a typography block default to the
@@ -186,4 +223,54 @@ internal static class ThemeJsonLoader
             throw new FormatException($"Theme JSON property '{name}' must be a number or null");
         return (float)v.GetDouble();
     }
+
+    // Missing / wrong-typed / unparseable colour slot -> built-in default + one warning.
+    private static uint ReadColorOrDefault(
+        JsonElement el,
+        string name,
+        uint fallback,
+        ILogger? logger
+    )
+    {
+        if (!el.TryGetProperty(name, out var v) || v.ValueKind != JsonValueKind.String)
+        {
+            logger?.LogWarning(
+                "Theme JSON colour slot '{Slot}' missing or not a string, using built-in default",
+                name
+            );
+            return fallback;
+        }
+
+        try
+        {
+            return ColourUtil.HexToRgba(v.GetString()!);
+        }
+        catch (FormatException)
+        {
+            logger?.LogWarning(
+                "Theme JSON colour slot '{Slot}' has an invalid hex value, using built-in default",
+                name
+            );
+            return fallback;
+        }
+    }
+
+    private static float ReadFloatOrDefault(
+        JsonElement el,
+        string name,
+        float fallback,
+        ILogger? logger
+    )
+    {
+        if (!el.TryGetProperty(name, out var v) || v.ValueKind != JsonValueKind.Number)
+        {
+            logger?.LogWarning(
+                "Theme JSON layout slot '{Slot}' missing or not a number, using built-in default",
+                name
+            );
+            return fallback;
+        }
+
+        return (float)v.GetDouble();
+    }
 }

HellionChat/Themes/ThemeRegistry.cs

@@ -626,7 +626,7 @@ public sealed class ThemeRegistry
             {
                 try
                 {
-                    theme = ThemeJsonLoader.LoadFromFile(path);
+                    theme = ThemeJsonLoader.LoadFromFile(path, _logger);
                     // null = hard-cut policy skipped a legacy v1 file. Leave
                     // theme null so the yield-guard below drops the entry.
                     if (theme is not null)

HellionChat/Ui/Components/Settings/ThemeImportExportRow.cs

@@ -150,7 +150,7 @@ internal sealed class ThemeImportExportRow
             Theme? theme;
             try
             {
-                theme = ThemeJsonLoader.LoadFromString(json);
+                theme = ThemeJsonLoader.LoadFromString(json, _logger);
             }
             catch (FormatException)
             {