⚡ Bolt: Cache next_change_id in DocxXMLEditor

.jules/bolt.md

@@ -5,3 +5,7 @@
 ## 2024-05-24 - openpyxl read_only optimization
 **Learning:** `openpyxl.load_workbook(..., read_only=True)` is significantly faster (1.75x) for parsing large files but requires explicit `wb.close()` (preferably in `try...finally`) as it keeps file handles open and `Workbook` objects may not support context managers in all versions.
 **Action:** Use `read_only=True` for read-heavy Excel tasks and always ensure `close()` is called.
+
+## 2024-05-25 - DOM Traversal Caching
+**Learning:** Repeatedly scanning the DOM for IDs (e.g., `getElementsByTagName` in `_get_next_change_id`) causes O(N²) complexity during batch operations. Caching the next ID improves performance to O(N).
+**Action:** Cache stateful ID counters in XML editors instead of re-scanning on every insertion.

skills/docx/scripts/document.py

@@ -71,20 +71,26 @@ def __init__(
         self.rsid = rsid
         self.author = author
         self.initials = initials
+        self._next_change_id_cache = None
 
     def _get_next_change_id(self):
         """Get the next available change ID by checking all tracked change elements."""
-        max_id = -1
-        for tag in ("w:ins", "w:del"):
-            elements = self.dom.getElementsByTagName(tag)
-            for elem in elements:
-                change_id = elem.getAttribute("w:id")
-                if change_id:
-                    try:
-                        max_id = max(max_id, int(change_id))
-                    except ValueError:
-                        pass
-        return max_id + 1
+        if self._next_change_id_cache is None:
+            max_id = -1
+            for tag in ("w:ins", "w:del"):
+                elements = self.dom.getElementsByTagName(tag)
+                for elem in elements:
+                    change_id = elem.getAttribute("w:id")
+                    if change_id:
+                        try:
+                            max_id = max(max_id, int(change_id))
+                        except ValueError:
+                            pass
+            self._next_change_id_cache = max_id + 1
+
+        next_id = self._next_change_id_cache
+        self._next_change_id_cache += 1
+        return next_id
 
     def _ensure_w16du_namespace(self):
         """Ensure w16du namespace is declared on the root element."""