Tag extension

Build a contract with the @tag extension defined as:

directive @tag(
  name: String!
) repeatable on FIELD_DEFINITION | INTERFACE | OBJECT | UNION | ARGUMENT_DEFINITION | SCALAR | ENUM | ENUM_VALUE | INPUT_OBJECT | INPUT_FIELD_DEFINITION

The contract key is a JSON with two optional keys includedTags and excludedTags:

{
  "includedTags": ["a"],
  "excludedTags": ["b"]
}

If the includedTags list is empty, the contract schema includes each type and object/interface field unless it's tagged with an excluded tag.

If the includedTags list is non-empty, the contract schema excludes each union type and object/interface field unless it's tagged with an included tag.

Unreachable types can be hidden with the following configuration:

[extensions.tag.config]
hide_unreachable_types = true