fixed a hydratioin issue

app/(app)/(builder)/builder/page.tsx

@@ -419,34 +419,36 @@ export default function GunbuilderPage() {
         if (!res.ok) throw new Error(`Failed to hydrate parts (${res.status})`);
   
         const data: GunbuilderProductFromApi[] = await res.json();
-  
-        const hydrated: Part[] = data
-        .map((p): Part | null => {
-          const normalizedRole = (p.partRole ?? "")
-            .trim()
-            .toLowerCase()
-            .replace(/_/g, "-");
-      
-          const categoryId = resolveCategoryId(normalizedRole);
-          if (!categoryId) return null;
-      
-          const buyUrl = p.buyUrl ?? undefined;
-      
-          return {
-            id: String(p.id),
-            categoryId,
-            name: p.name,
-            brand: p.brand,
-            price: p.price ?? 0,
-            imageUrl: p.imageUrl ?? undefined,
-            affiliateUrl: buyUrl,
-            url: buyUrl,
-            notes: undefined,
-          };
-        })
-        .filter((p): p is Part => p !== null);
-  
+
+        // Map products by id for quick lookup
+        const byId = new Map<string, GunbuilderProductFromApi>();
+        for (const p of data) byId.set(String(p.id), p);
+        
+        // Build the hydrated parts by iterating the BUILD STATE (slot -> id)
+        const hydrated: Part[] = Object.entries(build)
+          .filter(([, id]) => Boolean(id))
+          .map(([slot, id]) => {
+            const p = byId.get(String(id));
+            if (!p) return null;
+        
+            const buyUrl = p.buyUrl ?? undefined;
+        
+            return {
+              id: String(p.id),
+              categoryId: slot as any, // ✅ slot is the source of truth
+              name: p.name,
+              brand: p.brand,
+              price: p.price ?? 0,
+              imageUrl: p.imageUrl ?? undefined,
+              affiliateUrl: buyUrl,
+              url: buyUrl,
+              notes: undefined,
+            } as Part;
+          })
+          .filter((x): x is Part => x !== null);
+        
         setParts(hydrated);
+        
       } catch (err: any) {
         if (err?.name === "AbortError") return;
         setError(err?.message ?? "Failed to hydrate selected parts");