Examine source code of SwitchSearch

{
  "manifest_version": 3,
  "name": "SwitchSearch",
  "version": "1.8",
  "description": "Switch Search Engines Without Losing Your Query",
  "permissions": [
    "storage",
    "tabs",
    "contextMenus"
  ],
  "action": {
    "default_popup": "popup/popup.html",
    "default_icon": "images/icon48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "options_page": "settings/settings.html",
  "icons": {
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "switchsearch@thedmdim.github"
    }
  }
}