diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..7d437c6
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2024-05-24 - IconifyIcon Cache Null Type Constraint
+**Learning:** The custom `IconifyIcon` component requires caching negative results as `null` instead of `undefined` to satisfy Next.js build constraints for `ExtendedIconifyIcon | null`.
+**Action:** Always use `null` for missing items when caching `iconData` lookups in `IconifyIcon.tsx`.
diff --git a/client/src/components/base/IconifyIcon.tsx b/client/src/components/base/IconifyIcon.tsx
index b48f0dc..e9808fb 100644
--- a/client/src/components/base/IconifyIcon.tsx
+++ b/client/src/components/base/IconifyIcon.tsx
@@ -33,18 +33,37 @@ const iconSets: Record<string, IconifyJSON> = {
   "mdi-light": mdiLightIcons,
 };
 
+// ⚡ Bolt: Cache icon lookups to prevent O(N) array iteration on every render,
+// especially for prefix-less or missing icons.
+const iconCache = new Map<string, ReturnType<typeof getIconData>>();
+
 const iconData = (icon: string) => {
+  if (iconCache.has(icon)) {
+    return iconCache.get(icon);
+  }
+
   const [prefix, name] = icon.includes(":") ? icon.split(":") : ["", icon];
 
   if (prefix && iconSets[prefix]) {
     const data = getIconData(iconSets[prefix], name);
-    if (data) return data;
+    if (data) {
+      iconCache.set(icon, data);
+      return data;
+    }
   }
 
   for (const [_, icons] of Object.entries(iconSets)) {
     const data = getIconData(icons, name);
-    if (data) return data;
+    if (data) {
+      iconCache.set(icon, data);
+      return data;
+    }
   }
+
+  // ⚡ Bolt: Store missing items as `null` (not undefined)
+  // to satisfy the `ExtendedIconifyIcon | null` constraint in Next.js build.
+  iconCache.set(icon, null);
+  return null;
 };
 
 const IconifyIcon = ({