Type Alias VariableRequirement
VariableRequirement:
| { kind: "one"; message: string }
| { kind: "all"; message: string; names: readonly string[] }
| { kind: "any"; message: string; names: readonly string[] }
| { kind: "notOnly"; message: string; names: readonly string[] }
A single variable-presence requirement declared by an operation.
Mirrors the requirement shapes accepted by requireVariables, with the operation's error
messageattached so an operation can declare its whole validation contract as data.