Theme Builder: accordion panels across the full config surface, vertical-tab nav, reflective gallery

src/core/custom-theme.test.ts

@@ -155,4 +155,34 @@ describe('THEME_PREVIEW_SPECS', () => {
     );
     expect(colors.some((c) => c?.scale?.domainMid !== undefined)).toBe(true);
   });
+
+  it('uses bare marks so config controls are not shadowed in the preview', () => {
+    // A visual mark property hard-coded in a card overrides the same key in the
+    // injected config, making the matching Marks control a no-op in the gallery.
+    // Mark styling belongs in the config (a theme), never inline here.
+    const SHADOWING = [
+      'size',
+      'filled',
+      'point',
+      'innerRadius',
+      'outerRadius',
+      'cornerRadius',
+      'cornerRadiusEnd',
+      'opacity',
+      'interpolate',
+      'shape',
+      'strokeWidth',
+      'padAngle',
+      'discreteBandSize',
+      'continuousBandSize',
+    ];
+    for (const card of THEME_PREVIEW_SPECS) {
+      const mark: unknown = card.spec.mark;
+      if (mark && typeof mark === 'object') {
+        for (const key of SHADOWING) {
+          expect(mark, `${card.id} hard-codes mark.${key}`).not.toHaveProperty(key);
+        }
+      }
+    }
+  });
 });