Examine source code of Substack Notification Filter

{
  "manifest_version": 3,
  "name": "Substack Notification Filter",
  "version": "0.3.3",
  "description": "Filter Substack notifications by keywords, engagement, and follow status",
  "browser_specific_settings": {
    "gecko": {
      "id": "substack-filter@mythra.local",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "permissions": [
    "storage",
    "activeTab"
  ],
  "commands": {
    "toggle-filter": {
      "suggested_key": {
        "default": "Ctrl+Shift+F"
      },
      "description": "Toggle filtering on/off"
    },
    "show-filtered": {
      "suggested_key": {
        "default": "Ctrl+Shift+H"
      },
      "description": "Show/hide filtered notifications"
    }
  },
  "host_permissions": [
    "https://*.substack.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://substack.com/*",
        "https://*.substack.com/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "styles.css"
      ],
      "run_at": "document_end"
    }
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "developer": {
    "name": "mythraps",
    "url": "https://patreon.com/mythraps"
  }
}