Constant BOARD_FIELDS 

pub const BOARD_FIELDS: &str = r#"query($owner:String!,$number:Int!,$nestedFirst:Int!){
      boardFields:repositoryOwner(login:$owner){
        ... on ProjectV2Owner{projectV2(number:$number){id
          fields(first:$nestedFirst){nodes{
            ... on ProjectV2SingleSelectField{__typename id name options{id name}}
            ... on ProjectV2Field{__typename id name}
          }pageInfo{hasNextPage}}
        }}
      }
    }"#;

The board’s own id and field definitions, and not one of its items.

What a write needs of the board when the item it writes does not say: the id a field write and addProjectV2ItemById address, and the definitions of the Status and origin fields. It selects no items, so what it costs is the board’s field list however many items the board holds — and it decides nothing about which items those are, which is the question a read of one item by its own id answers instead.

The root is aliased boardFields rather than owner, so nothing counting the board’s item reads by their root counts this one among them.