iter(g141): 通知支持四角停靠

packages/skin/ui/src/notification.ts

@@ -1,15 +1,17 @@
 import { h } from '@ui-arch/frame';
 import type { NotificationProps } from './types.js';
 
-let host: HTMLElement | null = null; // 右下角堆叠容器：首条通知出现时懒创建
-const MAX_STACK = 3; // 同屏最多条数，超出挤掉最早一条
+const hosts = new Map<string, HTMLElement>(); // 每个角落一个堆叠容器，首次用到该角落时懒创建
+const MAX_STACK = 3; // 同一角落最多条数，超出挤掉最早一条
 
-/*** 确保堆叠容器存在：fixed 挂 body 末尾，与右上角 toast 分区不打架 ***/
-function ensureHost(): HTMLElement {
-  if (host) return host;
-  host = h('div', { class: 'ua-notice-host' });
-  document.body.appendChild(host);
-  return host;
+/*** 确保指定角落的堆叠容器存在：fixed 挂 body 末尾，与 toast 的右上角分区不打架 ***/
+function ensureHost(place: string): HTMLElement {
+  const hit = hosts.get(place);
+  if (hit) return hit;
+  const el = h('div', { class: `ua-notice-host is-${place}` });
+  document.body.appendChild(el);
+  hosts.set(place, el);
+  return el;
 }
 
 /*** 退场并移除：摘 ua-open 触发过渡，transitionend 与 320ms 超时二选一兜底 ***/
@@ -61,7 +63,7 @@ export function notification(props: NotificationProps): { el: HTMLElement; close
   el.addEventListener('focusin', pause); // 键盘聚焦到关闭/操作按钮同样暂停
   el.addEventListener('focusout', resume);
 
-  const stack = ensureHost();
+  const stack = ensureHost(props.placement ?? 'bottom-right'); // 缺省右下，与右上角 toast 错开
   if (stack.childElementCount >= MAX_STACK) stack.firstElementChild?.remove(); // 超出上限挤掉最早一条
   stack.appendChild(el);
   requestAnimationFrame(() => el.classList.add('ua-open')); // 下一帧入场，保证过渡生效