zammad/app/frontend/shared/entities/online-notification/graphql/mutations/markAllAsSeen.graphql

mutation onlineNotificationMarkAllAsSeen($onlineNotificationIds: [ID!]!) {
  onlineNotificationMarkAllAsSeen(
    onlineNotificationIds: $onlineNotificationIds
  ) {
    onlineNotifications {
      id
      seen
    }
    errors {
      ...errors
    }
  }
}