iter: b02 新增 toast 消息提示组件（四语义工厂 + 右上角堆叠 + 3s 自动消失）

packages/skin/ui/src/toast.ts

@@ -0,0 +1,37 @@
+import { h } from '@ui-arch/frame';
+import type { ToastProps } from './types.js';
+
+let host: HTMLElement | null = null; // 全局右上角堆叠容器：首条消息出现时懒创建
+let seq = 0; // 自增序号：为每条 toast 生成唯一 id，辅助无障碍定位
+
+/*** 确保堆叠容器存在：fixed 挂在 body 末尾，后续消息依次向上堆叠 ***/
+function ensureHost(): HTMLElement {
+  if (host) return host;
+  host = h('div', { class: 'ua-toast-host' });
+  document.body.appendChild(host);
+  return host;
+}
+
+/*** 弹出一条 toast：语义色由 variant 决定，duration 毫秒后自动淡出并移除节点 ***/
+export function showToast(props: ToastProps): HTMLElement {
+  // —— 状态集中声明 ——
+  const item = h('div', { class: `ua-toast ua-toast-${props.variant ?? 'info'}`, role: 'status', id: `ua-toast-${++seq}` }, props.message);
+  const duration = props.duration ?? 3000; // 停留时长毫秒
+
+  ensureHost().appendChild(item);
+  requestAnimationFrame(() => item.classList.add('ua-open')); // 下一帧入场，保证过渡生效
+  window.setTimeout(() => {
+    item.classList.remove('ua-open'); // 先退场再摘除，退场动画与 reduced-motion 兜底都安全
+    item.addEventListener('transitionend', () => item.remove(), { once: true });
+    window.setTimeout(() => item.isConnected && item.remove(), 320); // transition 不触发时的兜底移除
+  }, duration);
+  return item;
+}
+
+/*** toast 语义快捷工厂：toast.info / success / warning / error(message, duration?) ***/
+export const toast = {
+  info: (message: string, duration?: number): HTMLElement => showToast({ message, duration, variant: 'info' }),     // 中性信息
+  success: (message: string, duration?: number): HTMLElement => showToast({ message, duration, variant: 'success' }), // 成功反馈
+  warning: (message: string, duration?: number): HTMLElement => showToast({ message, duration, variant: 'warning' }), // 警告
+  error: (message: string, duration?: number): HTMLElement => showToast({ message, duration, variant: 'danger' }),    // 错误
+};