Examine source code of ToDoTube

{
  "manifest_version": 3,
  "name": "ToDoTube",
  "description": "Replace YouTube recommendations with your to-do list.",
  "version": "0.2.3",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "storage",
    "alarms"
  ],
  "host_permissions": [
    "*://*.youtube.com/*",
    "*://*.tiktok.com/*",
    "*://*.facebook.com/*",
    "*://*.threads.net/*",
    "*://*.threads.com/*",
    "*://*.x.com/*",
    "*://*.instagram.com/*",
    "https://api.ticktick.com/*",
    "https://ticktick.com/*"
  ],
  "optional_host_permissions": [
    "http://127.0.0.1:8765/*",
    "http://127.0.0.1:8930/*",
    "https://*/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "todotube@todotube.app",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_title": "ToDoTube",
    "default_popup": "popup.html"
  },
  "options_ui": {
    "open_in_tab": false,
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/*",
        "*://*.instagram.com/*",
        "*://*.threads.com/*",
        "*://*.threads.net/*",
        "*://*.tiktok.com/*",
        "*://*.x.com/*",
        "*://*.youtube.com/*"
      ],
      "exclude_matches": [
        "*://*.business.facebook.com/*",
        "*://*.music.youtube.com/*"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/blocked-sites.js"
      ]
    },
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "run_at": "document_idle",
      "js": [
        "content-scripts/youtube-watch.js"
      ]
    }
  ]
}