Examine source code of Gmailto

{
  "manifest_version": 3,
  "name": "Gmailto",
  "version": "1.0",
  "description": "Intercepts mailto links, copies address to clipboard, and opens Gmail compose window.",
  "permissions": [
    "clipboardWrite",
    "scripting",
    "tabs"
  ],
  "icons": {
    "48": "icon-48.png",
    "96": "icon-96.png",
    "128": "icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "host_permissions": [
    "*://*/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "gmailto@example.com",
      "strict_min_version": "102.0"
    }
  }
}