Examine source code of Nabereco Pocket

{
  "manifest_version": 3,
  "name": "Nabereco Pocket",
  "version": "1.0.4",
  "description": "ツイートをNabereco Pocketに保存",
  "browser_specific_settings": {
    "gecko": {
      "id": "nabereco-pocket@yaminaberecords.com",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "websiteContent"
        ]
      }
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "96": "icons/icon96.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "activeTab",
    "scripting",
    "tabs"
  ],
  "host_permissions": [
    "https://twitter.com/*",
    "https://x.com/*",
    "https://www.youtube.com/*",
    "https://nabereco-pocket-worker.nabereco.workers.dev/*"
  ],
  "optional_host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "96": "icons/icon96.png",
      "128": "icons/icon128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://twitter.com/*",
        "https://x.com/*",
        "https://www.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    },
    {
      "matches": [
        "https://pocket.yaminabe-records.com/*",
        "https://nabereco-pocket-igm3.vercel.app/*",
        "http://localhost/*"
      ],
      "js": [
        "bridge.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "externally_connectable": {
    "matches": [
      "https://pocket.yaminabe-records.com/*",
      "https://nabereco-pocket-igm3.vercel.app/*",
      "http://localhost/*"
    ]
  }
}