Examine source code of FL Identica

{
  "name": "FL Identica",
  "description": "Show corresponding item ID in its tooltip.",
  "version": "1.2.3",
  "manifest_version": 3,
  "permissions": [],
  "content_scripts": [
    {
      "matches": [
        "https://www.fallenlondon.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "action": {
    "default_icon": {
      "16": "/images/fl-wiki-icon-16.png",
      "32": "/images/fl-wiki-icon-32.png",
      "48": "/images/fl-wiki-icon-48.png",
      "128": "/images/fl-wiki-icon-128.png"
    }
  },
  "icons": {
    "16": "/images/fl-wiki-icon-16.png",
    "32": "/images/fl-wiki-icon-32.png",
    "48": "/images/fl-wiki-icon-48.png",
    "128": "/images/fl-wiki-icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a37fe7aa-999c-4982-8eb0-aaee91a2ca15}"
    }
  },
  "web_accessible_resources": [
    {
      "resources": [
        "inject.js"
      ],
      "matches": [
        "https://www.fallenlondon.com/*"
      ]
    }
  ]
}