Examine source code of Memento - Notes

{
  "manifest_version": 3,
  "name": "Memento",
  "description": "Simple notepad extension for Firefox",
  "version": "1.0.2",
  "browser_specific_settings": {
    "gecko": {
      "id": "memento@placidfox.org"
    }
  },
  "permissions": [
    "tabs",
    "activeTab",
    "storage"
  ],
  "action": {
    "default_icon": "images/icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}