fix(app): handle nullable detail consumers

apps/next/tests/component/agent-workspace-shell.test.tsx

@@ -0,0 +1,31 @@
+import { render, screen } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+
+import { AgentWorkspaceShell } from '../../src/components/agent-workspace/agent-workspace-shell';
+
+const { mockUseMutation, mockUseQuery } = vi.hoisted(() => ({
+  mockUseMutation: vi.fn(() => vi.fn()),
+  mockUseQuery: vi.fn(() => null),
+}));
+
+vi.mock('convex/react', () => ({
+  useMutation: mockUseMutation,
+  useQuery: mockUseQuery,
+}));
+
+vi.mock('sonner', () => ({
+  toast: {
+    error: vi.fn(),
+    success: vi.fn(),
+  },
+}));
+
+describe('AgentWorkspaceShell', () => {
+  it('renders a missing state when the job query returns null', () => {
+    render(<AgentWorkspaceShell jobId={'job-1' as never} />);
+
+    expect(
+      screen.getByText('This workspace was not found.'),
+    ).toBeInTheDocument();
+  });
+});