Examine source code of Gmail Reply Attach Helper

{
  "manifest_version": 3,
  "name": "Gmail Reply Attach Helper",
  "version": "1.0.1",
  "description": "Automatically include original email attachments when replying in Gmail.",
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "host_permissions": [
    "https://mail.google.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    },
    "default_title": "Gmail Reply Attach Helper"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "gmailmemo@memoli.com",
      "strict_min_version": "109.0"
    }
  }
}