Address review: cache WireframePalette per theme, fix namespace ref, fix inline badge whitespace edge case

Co-authored-by: jongalloway <68539+jongalloway@users.noreply.github.com>
Agent-Logs-Url: https://github.com/jongalloway/DiagramForge/sessions/04fdb593-36fa-43ae-a853-641cef1743a0

Author: Copilot

src/DiagramForge/Layout/DefaultLayoutEngine.Wireframe.cs

@@ -1,4 +1,5 @@
 using DiagramForge.Models;
+using DiagramForge.Parsers.Wireframe;
 using DiagramForge.Rendering;
 
 namespace DiagramForge.Layout;
@@ -50,7 +51,7 @@ private static void LayoutWireframeDiagram(Diagram diagram, Theme theme, double
         if (diagram.Nodes.Count == 0)
             return;
 
-        if (!diagram.Nodes.TryGetValue(Parsers.Wireframe.WireframeDslParser.RootNodeId, out var root))
+        if (!diagram.Nodes.TryGetValue(WireframeDslParser.RootNodeId, out var root))
             return;
 
         // Build parent→children map from wireframe:containment edges.

src/DiagramForge/Parsers/Wireframe/WireframeDslParser.cs

@@ -511,7 +511,9 @@ private static bool TrySplitInlineBadge(string line, out string badgeLabel, out
 
         badgeLabel = line[2..closeIdx].Trim();
         trailingText = line[(closeIdx + 2)..].Trim();
-        return badgeLabel.Length > 0;
+        // Require non-empty trailing text so a standalone badge with only trailing
+        // whitespace (e.g. "(( Info )) ") is not treated as an inline badge row.
+        return badgeLabel.Length > 0 && trailingText.Length > 0;
     }
 
     private static Node? ParseTabBar(string line, string nodeId)

src/DiagramForge/Rendering/SvgNodeWriter.cs

@@ -1,3 +1,4 @@
+using System.Runtime.CompilerServices;
 using System.Text;
 using DiagramForge.Models;
 
@@ -747,7 +748,7 @@ private static void AppendClassNode(
     /// <see cref="Theme.BackgroundColor"/>, <see cref="Theme.TextColor"/>,
     /// <see cref="Theme.AccentColor"/>, and <see cref="Theme.SubtleTextColor"/>.
     /// </summary>
-    private readonly record struct WireframePalette
+    private sealed record WireframePalette
     {
         public string CardFill { get; init; }
         public string CardBorder { get; init; }
@@ -825,9 +826,17 @@ public static WireframePalette FromTheme(Theme theme)
         }
     }
 
+    /// <summary>
+    /// Cache keyed by <see cref="Theme"/> identity so that <see cref="WireframePalette.FromTheme"/>
+    /// is computed at most once per distinct theme per process lifetime.
+    /// <see cref="ConditionalWeakTable{TKey,TValue}"/> is used so cached entries are automatically
+    /// discarded when the theme object is GC-collected.
+    /// </summary>
+    private static readonly ConditionalWeakTable<Theme, WireframePalette> s_paletteCache = new();
+
     private static void AppendWireframeNode(StringBuilder sb, Node node, string kind, Theme theme)
     {
-        var p = WireframePalette.FromTheme(theme);
+        var p = s_paletteCache.GetValue(theme, static t => WireframePalette.FromTheme(t));
 
         switch (kind)
         {

tests/DiagramForge.Tests/Parsers/WireframeDslParserTests.cs

@@ -577,4 +577,23 @@ public void Parse_StandaloneBadge_StillWorks()
         Assert.NotNull(badge);
         Assert.Equal("Info", badge!.Label.Text);
     }
+
+    [Fact]
+    public void Parse_StandaloneBadge_WithTrailingWhitespace_IsNotTreatedAsInline()
+    {
+        // A badge followed only by whitespace should NOT create an implicit row.
+        var diagram = _parser.Parse("wireframe\n(( Info )) ");
+
+        // No implicit row node should be created.
+        var row = diagram.Nodes.Values.FirstOrDefault(n =>
+            n.Metadata.TryGetValue("wireframe:kind", out var k) && k is "row"
+            && !n.Metadata.ContainsKey("wireframe:isRoot"));
+        Assert.Null(row);
+
+        // The badge should still be parsed as a standalone badge.
+        var badge = diagram.Nodes.Values.FirstOrDefault(n =>
+            n.Metadata.TryGetValue("wireframe:kind", out var k) && k is "badge");
+        Assert.NotNull(badge);
+        Assert.Equal("Info", badge!.Label.Text);
+    }
 }