Examine source code of Crossword Pencil

{
  "manifest_version": 3,
  "name": "Crossword Pencil",
  "version": "1.1",
  "description": "Activate NYT crossword pencil mode using Shift or Caps Lock.",
  "developer": {
    "name": "Max Gilmour",
    "url": "https://github.com/maxgmr/crosswordpencil"
  },
  "icons": {
    "32": "icons/icon.svg",
    "48": "icons/icon.svg",
    "64": "icons/icon.svg"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "crosswordpencil@maxgmr.ca",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.nytimes.com/crosswords/game/*"
      ],
      "js": [
        "src/pencil.js"
      ],
      "run_at": "document_idle"
    }
  ]
}