schema
  @link(url: "https://specs.apollo.dev/link/v1.0")
  @link(url: "https://specs.apollo.dev/join/v0.3", for: EXECUTION) {
  query: Query
}

directive @join__enumValue(graph: join__Graph!) repeatable on ENUM_VALUE

directive @join__field(
  graph: join__Graph
  requires: join__FieldSet
  provides: join__FieldSet
  type: String
  external: Boolean
  override: String
  usedOverridden: Boolean
) repeatable on FIELD_DEFINITION | INPUT_FIELD_DEFINITION

directive @join__graph(name: String!, url: String!) on ENUM_VALUE

directive @join__implements(
  graph: join__Graph!
  interface: String!
) repeatable on OBJECT | INTERFACE

directive @join__type(
  graph: join__Graph!
  key: join__FieldSet
  extension: Boolean! = false
  resolvable: Boolean! = true
  isInterfaceObject: Boolean! = false
) repeatable on OBJECT | INTERFACE | UNION | ENUM | INPUT_OBJECT | SCALAR

directive @join__unionMember(
  graph: join__Graph!
  member: String!
) repeatable on UNION

directive @link(
  url: String
  as: String
  for: link__Purpose
  import: [link__Import]
) repeatable on SCHEMA

scalar join__FieldSet

enum join__Graph {
  A @join__graph(name: "a", url: "http://0.0.0.0:4200/a")
  B @join__graph(name: "b", url: "http://0.0.0.0:4200/b")
}

scalar link__Import

enum link__Purpose {
  SECURITY
  EXECUTION
}

type Query @join__type(graph: A) {
  # Non-null element: distributed happy-path resolution.
  feed: [Media!]! @join__field(graph: A)
  # Nullable element: a collapsed member survives as `null`, siblings remain.
  feedNullable: [Media]! @join__field(graph: A)
}

# `__typename` + key are resolved in subgraph A; the type-specific fields below
# come from subgraph B via per-concrete-type `_entities` fetches.
union Media
  @join__type(graph: A)
  @join__unionMember(graph: A, member: "Photo")
  @join__unionMember(graph: A, member: "Video") =
  | Photo
  | Video

type Photo
  @join__type(graph: A, key: "id")
  @join__type(graph: B, key: "id") {
  id: ID!
  caption: String! @join__field(graph: B)
}

type Video
  @join__type(graph: A, key: "id")
  @join__type(graph: B, key: "id") {
  id: ID!
  duration: Int! @join__field(graph: B)
}
