重构(会员弹层)：抽取 resolveRovingIndex 复用方向键索引

- 页签列表与泥点档位网格共用同一个 roving index 解析函数
- 用 switch 取代深层嵌套三元，Home/End/左右键语义保持不变

packages/shared/src/components/PlatformProfileRechargeModal/index.tsx

@@ -36,6 +36,32 @@ import { resolveMembershipProductId } from './membershipProduct';
 
 const WECHAT_NATIVE_PAY_QR_IMAGE_SIZE = 180;
 
+/**
+ * roving tabindex / radiogroup 的方向键索引解析：`Home` / `End` 跳首尾，左右键循环，
+ * 其余按键返回 `null`（调用方据此忽略事件）。`currentIndex` 允许为 `-1`（未选中）。
+ */
+function resolveRovingIndex(
+  key: string,
+  currentIndex: number,
+  length: number,
+): number | null {
+  if (length <= 0) {
+    return null;
+  }
+  switch (key) {
+    case 'Home':
+      return 0;
+    case 'End':
+      return length - 1;
+    case 'ArrowLeft':
+      return (currentIndex - 1 + length) % length;
+    case 'ArrowRight':
+      return (currentIndex + 1) % length;
+    default:
+      return null;
+  }
+}
+
 type PlatformProfileRechargeTab = 'subscription' | 'recharge';
 
 export type PlatformProfileRechargeNativePaymentState = {
@@ -511,20 +537,16 @@ function PlatformRechargeTabNav({
       aria-label="会员与泥点"
       className="platform-subpanel flex gap-1 rounded-full p-1"
       onKeyDown={(event) => {
-        if (!['ArrowLeft', 'ArrowRight', 'Home', 'End'].includes(event.key)) {
+        const currentIndex = tabs.findIndex((tab) => tab.id === activeTab);
+        const nextIndex = resolveRovingIndex(
+          event.key,
+          currentIndex,
+          tabs.length,
+        );
+        if (nextIndex === null) {
           return;
         }
         event.preventDefault();
-        const currentIndex = tabs.findIndex((tab) => tab.id === activeTab);
-        const nextIndex =
-          event.key === 'Home'
-            ? 0
-            : event.key === 'End'
-              ? tabs.length - 1
-              : (currentIndex +
-                  (event.key === 'ArrowRight' ? 1 : -1) +
-                  tabs.length) %
-                tabs.length;
         const nextTab = tabs[nextIndex];
         if (nextTab) {
           onChange(nextTab.id);
@@ -851,22 +873,18 @@ function PlatformPointProductGrid({
       aria-label="泥点充值档位"
       className="grid grid-cols-2 gap-2 sm:grid-cols-3"
       onKeyDown={(event) => {
-        if (!['ArrowLeft', 'ArrowRight', 'Home', 'End'].includes(event.key)) {
-          return;
-        }
-        event.preventDefault();
         const currentIndex = products.findIndex(
           (product) => product.productId === selectedProductId,
         );
-        const nextIndex =
-          event.key === 'Home'
-            ? 0
-            : event.key === 'End'
-              ? products.length - 1
-              : (currentIndex +
-                  (event.key === 'ArrowRight' ? 1 : -1) +
-                  products.length) %
-                products.length;
+        const nextIndex = resolveRovingIndex(
+          event.key,
+          currentIndex,
+          products.length,
+        );
+        if (nextIndex === null) {
+          return;
+        }
+        event.preventDefault();
         const nextProduct = products[nextIndex];
         if (nextProduct) {
           onSelect(nextProduct);