test(examples/ag-ui): interrupt-approval e2e over the AG-UI transport

Ports examples/chat's interrupt spec: request_approval pauses the run via
on_interrupt, and the app shell's <chat-interrupt-panel> (#649) renders the
captured reason + Accept/Edit/Respond/Ignore. The interrupt-approval.json
aimock fixture already shipped with the harness — only the spec was missing.
10/10 suite green locally.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: blove

examples/ag-ui/angular/e2e/interrupt-approval.spec.ts

@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: MIT
+import { test, expect } from '@playwright/test';
+import { openDemo } from './test-helpers';
+
+const PROMPT =
+  'I want to clean up old database backups older than 90 days. Walk me through ' +
+  'what you would delete, and call request_approval before doing anything ' +
+  'destructive so I can review your plan.';
+
+// Mirrors examples/chat's interrupt-approval spec over the AG-UI transport:
+// the langgraph node calls interrupt({...}), ag-ui-langgraph emits the
+// on_interrupt CUSTOM event, the adapter populates agent.interrupt(), and the
+// app shell renders <chat-interrupt-panel> (added for parity in #649).
+test('interrupt approval: pause renders the interrupt panel with the captured reason', async ({
+  page,
+}) => {
+  await openDemo(page);
+
+  const input = page.getByRole('textbox', { name: /message|prompt/i });
+  await input.fill(PROMPT);
+  await page.getByRole('button', { name: /send/i }).click();
+
+  // The run stays paused until a human responds — the interrupt panel is the
+  // durable signal, so don't wait on streaming-complete.
+  const panel = page.locator('chat-interrupt-panel');
+  await expect(panel).toBeAttached({ timeout: 45_000 });
+
+  await expect(panel).toContainText(/agent paused/i);
+
+  // The captured reason mentions the destructive plan — assert it plumbed
+  // through the on_interrupt payload to the panel body.
+  await expect.poll(
+    async () => (await panel.innerText()).toLowerCase(),
+    { timeout: 30_000 },
+  ).toMatch(/approval|delete|backup/i);
+
+  await expect(panel.getByRole('button', { name: /accept/i })).toBeVisible();
+  await expect(panel.getByRole('button', { name: /edit|respond/i }).first()).toBeVisible();
+  await expect(panel.getByRole('button', { name: /ignore/i })).toBeVisible();
+  await expect(page.locator('chat-message').filter({ has: panel })).toHaveCount(0);
+});