Examine source code of MacCal

{
  "description": "Generate an .ics (calendar) file using the details on your MyTimetable page!",
  "name": "MacCal",
  "version": "1.0.6",
  "manifest_version": 3,
  "background": {
    "scripts": [
      "background/background.js"
    ]
  },
  "icons": {
    "16": "static/icons/maccal_icon16.png",
    "32": "static/icons/maccal_icon32.png",
    "64": "static/icons/maccal_icon64.png",
    "128": "static/icons/maccal_icon128.png"
  },
  "action": {
    "default_icon": {
      "16": "static/icons/maccal_icon16.png",
      "32": "static/icons/maccal_icon32.png",
      "64": "static/icons/maccal_icon64.png",
      "128": "static/icons/maccal_icon128.png"
    },
    "default_title": "MacCal",
    "default_popup": "static/index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0d3fc01c-cb46-4a21-8c6d-9bf7ebe8e765}",
      "strict_min_version": "109.0"
    }
  },
  "content_security_policy": {
    "extension_pages": "default-src 'self'"
  },
  "permissions": [
    "activeTab",
    "scripting"
  ]
}