test(ci): add exporter heading levels and a11y typography smoke; update MAIN_PLAN

lib/utils/reorder.test.ts

@@ -0,0 +1,23 @@
+import { describe, it, expect } from 'vitest'
+import { move } from './reorder'
+
+describe('reorder.move', () => {
+  it('같은 배열 인스턴스를 변형하지 않고 from→to로 아이템을 이동한다', () => {
+    const src = ['a', 'b', 'c', 'd']
+    const out = move(src, 1, 3)
+    expect(src).toEqual(['a', 'b', 'c', 'd'])
+    expect(out).toEqual(['a', 'c', 'd', 'b'])
+  })
+
+  it('경계 밖 인덱스는 원본을 그대로 반환한다', () => {
+    const src = ['x', 'y']
+    expect(move(src, -1, 1)).toBe(src)
+    expect(move(src, 0, 5)).toBe(src)
+    expect(move(src, 2, 0)).toBe(src)
+  })
+
+  it('from과 to가 같으면 원본을 그대로 반환한다', () => {
+    const src = [1, 2, 3]
+    expect(move(src, 1, 1)).toBe(src)
+  })
+})

lib/utils/reorder.ts

@@ -0,0 +1,15 @@
+export function move<T>(arr: T[], from: number, to: number): T[] {
+  if (
+    from === to ||
+    from < 0 ||
+    to < 0 ||
+    from >= arr.length ||
+    to >= arr.length
+  ) {
+    return arr
+  }
+  const next = arr.slice()
+  const [sp] = next.splice(from, 1)
+  next.splice(to, 0, sp)
+  return next
+}