PyQGIS Composer Map Extends in layer

map_extends.py

from qgis.core import *
from PyQt5.QtCore import QVariant

project = QgsProject.instance()
projectLayoutManager = project.layoutManager()
layout = projectLayoutManager.layoutByName('KIERUNKI_A0+')
treeRoot = project.layerTreeRoot()

temp = QgsVectorLayer("Polygon?crs=epsg:2180", "map_extends", "memory")
temp_data = temp.dataProvider()
temp.startEditing()

temp_data.addAttributes([QgsField('ID', QVariant.String)])
temp.updateFields()

for item in layout.items():
  if type(item) == QgsLayoutItemMap:
    feat = QgsFeature()
    feat.setGeometry(QgsGeometry.fromRect(item.extent()))
    feat.initAttributes(1)
    feat.setAttribute(0,item.id())
    temp.addFeature(feat)
    temp.updateExtents()

temp.commitChanges()
treeRoot.addLayer(temp)