Examine source code of FixVX Link

{
  "manifest_version": 3,
  "name": "FixVX Link Copier",
  "browser_specific_settings": {
    "gecko": {
      "id": "@fixvxlinkcopier.steffen",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "version": "1.0",
  "description": "Automatically replaces x.com with fixvx.com when copying links.",
  "permissions": [],
  "host_permissions": [
    "*://twitter.com/*",
    "*://x.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://twitter.com/*",
        "*://x.com/*"
      ],
      "js": [
        "inject.js"
      ],
      "run_at": "document_start",
      "world": "MAIN"
    }
  ]
}