iter(g11): 浮层空间不足时自动翻转

packages/skin/ui/src/select.ts

@@ -1,10 +1,12 @@
 import { effect, h, signal } from '@ui-arch/frame';
 import type { SelectProps } from './types.js';
+import { flip } from './position.js';
 
 /*** 下拉选择：自绘弹层替代原生 select，value 信号双向绑定；支持 ↑↓/Home/End 键盘导航，点选项 / 点外部 / Esc 关闭 ***/
 export function select(props: SelectProps): HTMLElement {
   // —— 状态集中声明 ——
   const open = signal(false);              // 弹层开合
+  const place = signal<'top' | 'bottom'>('bottom'); // 实际生效方位：打开时按视口空间自动翻转
   const value = props.value ?? signal(''); // 选中值；未传信号则内部持有
 
   const labelOf = (v: string) => props.options.find((o) => o.value === v)?.label ?? '';
@@ -45,7 +47,7 @@ export function select(props: SelectProps): HTMLElement {
       opt.label,
     ),
   );
-  const pop = h('div', { class: () => `ua-select-pop${open() ? ' ua-open' : ''}`, role: 'listbox' }, ...options);
+  const pop = h('div', { class: () => `ua-select-pop${open() ? ' ua-open' : ''}${place() === 'top' ? ' is-flip' : ''}`, role: 'listbox' }, ...options);
 
   const root = h('div', { class: () => `ua-select${open() ? ' ua-open' : ''}` }, trigger, pop); // 根带开合类，供箭头旋转
 
@@ -68,5 +70,6 @@ export function select(props: SelectProps): HTMLElement {
     open(false); // 点外部关闭
   });
   effect(() => open()); // 建立依赖，保证开合信号生效
+  effect(() => { if (open()) place(flip(trigger, pop, 'bottom')); }); // 每次打开重算方位：空间不足自动翻转
   return root;
 }