feat(screener): useScreenerMode hook (form|canvas + localStorage)

src/pages/stock/screener/hooks/useScreenerMode.js

@@ -0,0 +1,25 @@
+import { useState } from 'react';
+
+const STORAGE_KEY = 'screener-mode-v1';
+const VALID_MODES = new Set(['form', 'canvas']);
+
+function readMode() {
+  try {
+    const v = localStorage.getItem(STORAGE_KEY);
+    return VALID_MODES.has(v) ? v : 'form';
+  } catch {
+    return 'form';
+  }
+}
+
+export function useScreenerMode() {
+  const [mode, setModeState] = useState(readMode);
+
+  const setMode = (m) => {
+    if (!VALID_MODES.has(m)) return;
+    setModeState(m);
+    try { localStorage.setItem(STORAGE_KEY, m); } catch {}
+  };
+
+  return { mode, setMode };
+}

src/pages/stock/screener/hooks/useScreenerMode.test.js

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+import { describe, it, expect } from 'vitest';
+import { renderHook, act } from '@testing-library/react';
+import { useScreenerMode } from './useScreenerMode';
+
+describe('useScreenerMode', () => {
+  it('초기값은 "form"', () => {
+    const { result } = renderHook(() => useScreenerMode());
+    expect(result.current.mode).toBe('form');
+  });
+
+  it('localStorage 에 저장된 값 복원', () => {
+    localStorage.setItem('screener-mode-v1', 'canvas');
+    const { result } = renderHook(() => useScreenerMode());
+    expect(result.current.mode).toBe('canvas');
+  });
+
+  it('손상된 localStorage 는 "form" 으로 fallback', () => {
+    localStorage.setItem('screener-mode-v1', 'INVALID_MODE');
+    const { result } = renderHook(() => useScreenerMode());
+    expect(result.current.mode).toBe('form');
+  });
+
+  it('setMode 호출 시 state 와 localStorage 모두 갱신', () => {
+    const { result } = renderHook(() => useScreenerMode());
+    act(() => result.current.setMode('canvas'));
+    expect(result.current.mode).toBe('canvas');
+    expect(localStorage.getItem('screener-mode-v1')).toBe('canvas');
+  });
+});