feat(frontend): collapsible group headers; resume/delete integration tests; English test name

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/shell/AppShell.session-mgmt.test.tsx

@@ -3,6 +3,7 @@ import userEvent from "@testing-library/user-event";
 import { http, HttpResponse } from "msw";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import { server } from "../test/msw";
+import { FakeEventSource } from "../test/fakeEventSource";
 import { AppShell } from "./AppShell";
 
 function wrap() {
@@ -16,6 +17,8 @@ const LIST = [
 ];
 
 beforeEach(() => {
+  FakeEventSource.instances = [];
+  (globalThis as any).EventSource = FakeEventSource;
   server.use(
     http.get("http://localhost:8787/sessions", () => HttpResponse.json(LIST)),
     http.get("http://localhost:8787/sessions/:id/documents", () => HttpResponse.json([
@@ -43,3 +46,19 @@ test("Archive toggle reveals archived sessions", async () => {
   await userEvent.click(await screen.findByRole("button", { name: /archive/i }));
   expect(await screen.findByText("Archiviata due")).toBeInTheDocument();
 });
+
+test("Resume from the panel activates the session and closes the panel", async () => {
+  let resumed: string | null = null;
+  server.use(
+    http.post("http://localhost:8787/sessions/:id/resume", ({ params }) => {
+      resumed = params.id as string;
+      return new HttpResponse(null, { status: 204 });
+    }),
+  );
+  wrap();
+  await userEvent.click(await screen.findByText("Attiva uno"));
+  await screen.findByText("Domanda originale"); // panel open
+  await userEvent.click(screen.getByRole("button", { name: /resume/i }));
+  await waitFor(() => expect(resumed).toBe("s1"));
+  await waitFor(() => expect(screen.queryByText("Domanda originale")).not.toBeInTheDocument()); // panel closed
+});