part cards

components/CategoryColumn.tsx

@@ -17,10 +17,10 @@ export function CategoryColumn({
   selectedPartId,
   onSelectPart,
 }: CategoryColumnProps) {
-  // Show selected part if available, otherwise show first part
+  // Show selected part if available, otherwise show placeholder
   const displayedPart = selectedPartId
-    ? parts.find((p) => p.id === selectedPartId) || parts[0]
-    : parts[0];
+    ? parts.find((p) => p.id === selectedPartId)
+    : null;
 
   return (
     <div className="flex flex-col h-full">
@@ -33,6 +33,11 @@ export function CategoryColumn({
         {parts.length === 0 && (
           <p className="text-xs text-zinc-500">No parts yet for this category.</p>
         )}
+        {!displayedPart && parts.length > 0 && (
+          <div className="w-full border border-zinc-700 rounded-md p-3 mb-2 text-center">
+            <p className="text-sm text-zinc-500">Choose a Part</p>
+          </div>
+        )}
         {displayedPart && (
           <PartCard
             key={displayedPart.id}