feat(dees-table): add opt-in flash highlighting for updated table cells

ts_web/elements/00group-dataview/dees-table/dees-table.demo.ts

@@ -1,6 +1,7 @@
 import { type ITableAction } from './dees-table.js';
 import * as plugins from '../../00plugins.js';
 import { html, css, cssManager } from '@design.estate/dees-element';
+import '@design.estate/dees-wcctools/demotools';
 
 interface ITableDemoData {
   date: string;
@@ -742,6 +743,71 @@ export const demoFunc = () => html`
           ] as ITableAction[]}
         ></dees-table>
       </div>
+
+      <dees-demowrapper .runAfterRender=${async (elementArg: HTMLElement) => {
+        const tableEl = elementArg.querySelector('#demoLiveFlash') as any;
+        if (!tableEl) return;
+        // Guard against double-start if runAfterRender fires more than once
+        // (e.g. across hot-reload cycles).
+        if (tableEl.__liveFlashTimerId) {
+          window.clearInterval(tableEl.__liveFlashTimerId);
+        }
+        const tick = () => {
+          if (!Array.isArray(tableEl.data) || tableEl.data.length === 0) return;
+          const next = tableEl.data.map((r: any) => ({ ...r }));
+          const count = 1 + Math.floor(Math.random() * 3);
+          for (let i = 0; i < count; i++) {
+            const idx = Math.floor(Math.random() * next.length);
+            const delta = +((Math.random() * 2 - 1) * 3).toFixed(2);
+            const newPrice = Math.max(1, +(next[idx].price + delta).toFixed(2));
+            next[idx] = {
+              ...next[idx],
+              price: newPrice,
+              change: delta,
+              updatedAt: new Date().toLocaleTimeString(),
+            };
+          }
+          tableEl.data = next;
+        };
+        tableEl.__liveFlashTimerId = window.setInterval(tick, 1500);
+      }}>
+        <div class="demo-section">
+          <h2 class="demo-title">Live Updates with Flash Highlighting</h2>
+          <p class="demo-description">
+            Opt-in cell-flash via <code>highlight-updates="flash"</code>. The ticker below mutates
+            random rows every 1.5s and reassigns <code>.data</code>. Updated cells briefly flash
+            amber and fade out. Requires <code>rowKey</code> (here <code>"symbol"</code>). Honors
+            <code>prefers-reduced-motion</code>. Row selection persists across updates — click a
+            row, then watch it stay selected as the data churns.
+          </p>
+          <dees-table
+            id="demoLiveFlash"
+            .rowKey=${'symbol'}
+            highlight-updates="flash"
+            .selectionMode=${'multi'}
+            heading1="Live Market Feed"
+            heading2="Flashing cells indicate updated values"
+            .columns=${[
+              { key: 'symbol', header: 'Symbol', sortable: true },
+              { key: 'price', header: 'Price', sortable: true },
+              { key: 'change', header: 'Δ', sortable: true },
+              { key: 'updatedAt', header: 'Updated' },
+            ]}
+            .data=${[
+              { symbol: 'AAPL', price: 182.52, change: 0, updatedAt: '—' },
+              { symbol: 'MSFT', price: 414.18, change: 0, updatedAt: '—' },
+              { symbol: 'GOOG', price: 168.74, change: 0, updatedAt: '—' },
+              { symbol: 'AMZN', price: 186.13, change: 0, updatedAt: '—' },
+              { symbol: 'TSLA', price: 248.50, change: 0, updatedAt: '—' },
+              { symbol: 'NVDA', price: 877.35, change: 0, updatedAt: '—' },
+              { symbol: 'META', price: 492.96, change: 0, updatedAt: '—' },
+              { symbol: 'NFLX', price: 605.88, change: 0, updatedAt: '—' },
+              { symbol: 'AMD',  price: 165.24, change: 0, updatedAt: '—' },
+              { symbol: 'INTC', price:  42.15, change: 0, updatedAt: '—' },
+            ]}
+          ></dees-table>
+        </div>
+      </dees-demowrapper>
     </div>
   </div>
 `;