Persist sort order list across reloads

frontend/src/App.jsx

@@ -35,7 +35,17 @@ const App = () => {
   const [isManageMilestonesOpen, setIsManageMilestonesOpen] = useState(false);
   const [isManageLabelsOpen, setIsManageLabelsOpen] = useState(false);
   const [isManageSortOpen, setIsManageSortOpen] = useState(false);
-  const [sortOrder, setSortOrder] = useState([]);
+
+  // Load sort order from localStorage on mount
+  const [sortOrder, setSortOrder] = useState(() => {
+    try {
+      const saved = localStorage.getItem('issueSortOrder');
+      return saved ? JSON.parse(saved) : [];
+    } catch (error) {
+      console.error('Failed to load sort order from localStorage:', error);
+      return [];
+    }
+  });
 
   useEffect(() => {
     fetchProject()
@@ -142,6 +152,15 @@ const App = () => {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, []);
 
+  // Save sort order to localStorage whenever it changes
+  useEffect(() => {
+    try {
+      localStorage.setItem('issueSortOrder', JSON.stringify(sortOrder));
+    } catch (error) {
+      console.error('Failed to save sort order to localStorage:', error);
+    }
+  }, [sortOrder]);
+
   const loadMilestones = () => {
     setLoading(true);
     setError(null);

frontend/src/App.test.jsx

@@ -10,8 +10,29 @@ import assigneesCache from './utils/assigneesCache';
 vi.mock('./services/api');
 
 describe('App', () => {
+  // Mock localStorage
+  let store = {};
+  const localStorageMock = {
+    getItem: vi.fn((key) => store[key] || null),
+    setItem: vi.fn((key, value) => {
+      store[key] = value.toString();
+    }),
+    removeItem: vi.fn((key) => {
+      delete store[key];
+    }),
+    clear: vi.fn(() => {
+      store = {};
+    }),
+  };
+
   beforeEach(() => {
     vi.clearAllMocks();
+    // Clear localStorage mock store
+    store = {};
+    Object.defineProperty(window, 'localStorage', {
+      value: localStorageMock,
+      writable: true,
+    });
     clearMilestonesCache();
     clearLabelsCache();
     // Clear assignees cache
@@ -139,4 +160,59 @@ describe('App', () => {
       expect(screen.getByText(/No milestones found/i)).toBeInTheDocument();
     });
   });
+
+  it('loads sort order from localStorage on mount', async () => {
+    const savedSortOrder = ['label1', 'label2', 'label3'];
+    localStorageMock.setItem('issueSortOrder', JSON.stringify(savedSortOrder));
+    api.fetchMilestones.mockResolvedValue([]);
+
+    await act(async () => {
+      render(<App />);
+    });
+
+    await waitFor(() => {
+      // Verify localStorage.getItem was called
+      expect(localStorageMock.getItem).toHaveBeenCalledWith('issueSortOrder');
+    });
+  });
+
+  it('saves sort order to localStorage when changed', async () => {
+    api.fetchMilestones.mockResolvedValue([]);
+    api.fetchLabels.mockResolvedValue([
+      { name: 'label1', color: 'ff0000', description: 'Label 1' },
+      { name: 'label2', color: '00ff00', description: 'Label 2' },
+    ]);
+
+    await act(async () => {
+      render(<App />);
+    });
+
+    await waitFor(() => {
+      expect(screen.getByText('Sort')).toBeInTheDocument();
+    });
+
+    // Open the Sort modal
+    const sortButton = screen.getByText('Sort');
+    await act(async () => {
+      sortButton.click();
+    });
+
+    await waitFor(() => {
+      expect(screen.getByText(/Sort Issues by Labels/i)).toBeInTheDocument();
+    });
+
+    // Add a label to the sort order
+    const addLabelButton = screen.getByText('+ label1');
+    await act(async () => {
+      addLabelButton.click();
+    });
+
+    // Verify localStorage.setItem was called with the new sort order
+    await waitFor(() => {
+      expect(localStorageMock.setItem).toHaveBeenCalledWith(
+        'issueSortOrder',
+        JSON.stringify(['label1'])
+      );
+    });
+  });
 });