 //
 //===----------------------------------------------------------------------===//
 
+import Swift
+
 // TODO(distributed): not thread safe...
 public final class LocalTestingDistributedActorSystem: DistributedActorSystem, @unchecked Sendable {
   public typealias ActorID = ActorAddress
-  public typealias InvocationEncoder = LocalInvocationEncoder
-  public typealias InvocationDecoder = LocalInvocationDecoder
+  public typealias InvocationEncoder = LocalTestingInvocationEncoder
+  public typealias InvocationDecoder = LocalTestingInvocationDecoder
   public typealias SerializationRequirement = Codable
 
   private var activeActors: [ActorID: any DistributedActor] = [:]

  }
}

public struct LocalInvocationEncoder: DistributedTargetInvocationEncoder {
  public typealias SerializationRequirement = Codable

  public mutating func recordGenericSubstitution<T>(_ type: T.Type) throws {

  }
}

public class LocalTestingInvocationDecoder : DistributedTargetInvocationDecoder {
  public typealias SerializationRequirement = Codable

  public func decodeGenericSubstitutions() throws -> [Any.Type] {
