fix: finalize session after memory promotion

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

@@ -125,6 +125,31 @@ test("WIP icon toggles the Model activity panel and shows the streamed text", as
   expect(screen.getByText(/FIRSTLINE/)).toBeInTheDocument();
 });
 
+test("session finalization shows the completion banner and returns to landing", async () => {
+  useSessionStore.getState().resetSession();
+  let finalized = false;
+  server.use(
+    http.post("http://localhost:8787/sessions/:id/resume", () => new HttpResponse(null, { status: 204 })),
+    http.get("http://localhost:8787/sessions", () =>
+      HttpResponse.json(finalized ? [{ ...LIST[0], status: "finalized" }] : LIST)),
+  );
+  wrap();
+  await userEvent.click(await screen.findByText("Attiva uno"));
+  await userEvent.click(await screen.findByRole("button", { name: /resume/i }));
+  // The final turn ends: the session is now finalized on disk and agent_end
+  // arrives — the shell must refetch immediately (not wait for the 10s poll)
+  // and surface the new-session invite.
+  finalized = true;
+  act(() => {
+    useSessionStore.getState().applyEvent({ type: "system_event", event: "agent_end" } as any);
+  });
+  const cta = await screen.findByRole("button", { name: /start a new question/i });
+  expect(screen.getByText(/session completed and finalized/i)).toBeInTheDocument();
+  await userEvent.click(cta);
+  // Landing state: the composer invites a brand-new question.
+  expect(await screen.findByText(/type your question/i)).toBeInTheDocument();
+});
+
 test("renaming a group reassigns its members via setSessionGroup", async () => {
   const groupSets: Array<{ id: string; group: string }> = [];
   server.use(