修复: op 引擎 undo 逆操作 z序/越界缺陷,补 14 项核心测试

src/core/op.ts

@@ -40,6 +40,8 @@ export interface Op {
 export interface HistoryEntry {
   forward: Op
   backward: Op
+  /** 批次标记：同批多条（如一次导入 N 张图）undo/redo 时整组一起回滚 */
+  group?: string
 }
 
 /* ---------- 工具 ---------- */
@@ -107,8 +109,12 @@ export function applyOp(inputDeck: Deck, op: Op): Deck {
     case 'add_element': {
       const slideIdx = op.slideIdx as number
       const element = op.element as SlideElement
+      const atIndex = op.atIndex as number | undefined
       const s = deck.slides[slideIdx]
-      if (s) s.elements.push(element)
+      if (s) {
+        if (atIndex != null) s.elements.splice(atIndex, 0, element)  // 指定位置插入（撤销删除时回到原 z 序）
+        else s.elements.push(element)
+      }
       break
     }
 
@@ -244,18 +250,34 @@ export function invertOp(inputDeck: Deck, op: Op): Op {
     }
 
     case 'del_element': {
-      // 逆：把删掉的元素加回去
+      // 逆：把删掉的元素加回原位置（保持 z 序）
       const slideIdx = op.slideIdx as number
       const deletedElement = op.deletedElement as SlideElement | undefined
       if (deletedElement) {
-        return { type: 'add_element', slideIdx, element: deletedElement }
+        const s = deck.slides[slideIdx]
+        const at = s ? s.elements.findIndex(e => e.id === deletedElement.id) : -1
+        // 已删状态里找不到 → 原位置 = 删除后第一个"本应在其后"的元素处；用 indexOf 拿不到，
+        // 所以在执行前由 invertOp 拿到 index：这里 s.elements 已无该元素，取其后继位置
+        const insertAt = at >= 0 ? at : (s ? s.elements.length : 0)
+        return { type: 'add_element', slideIdx, element: deletedElement, atIndex: insertAt }
       }
       return { type: 'replace_deck', deck: clone(deck) }
     }
 
     case 'move_element_z': {
-      // 逆：方向反过来
-      return { type: 'move_element_z', slideIdx: op.slideIdx, elementId: op.elementId, dir: -(op.dir as number) }
+      // 逆：方向反过来。正向若越界是 no-op（applyOp break），
+      // 此时逆必须也是 no-op（空 patch 的 update_element 无副作用）——
+      // 否则撤销会移动一个从未移动过的元素
+      const slideIdx = op.slideIdx as number
+      const elementId = op.elementId as string
+      const s = deck.slides[slideIdx]
+      const i = s ? s.elements.findIndex(e => e.id === elementId) : -1
+      const j = i >= 0 ? ((op.dir as number) > 0 ? i + 1 : i - 1) : -1
+      const outOfRange = i < 0 || j < 0 || j >= (s ? s.elements.length : 0)
+      if (outOfRange) {
+        return { type: 'update_element', slideIdx, elementId, patch: {} }
+      }
+      return { type: 'move_element_z', slideIdx, elementId, dir: -(op.dir as number) }
     }
 
     case 'set_theme': {