engine: memory
db: todomvc

Todo as Node {
  id: ID<Todo>
  listId: ID<TodoList>
  text: string
  completed: bool
}

TodoList as Node {
  id: ID<TodoList>
  filter: Enumeration<all | active | completed>
  editing: ID<Todo> | null
} & OutboundEdges {
  todos: Edge<Todo.listId>
}