package fdk:extension@0.1.0;

interface engine {
  /// Calls an engine statement and waits for its result.
  ///
  /// `path` is the full gRPC method path, such as `/spatialengine.v1.std.Std/Print`.
  /// `payload` is the serialized protobuf request message, without gRPC framing.
  /// Obtain request and response definitions from the engine's exported protobuf schema.
  ///
  /// `transaction-id` joins an existing transaction when present. Its value is a UUID string.
  /// Omit it for calls outside a transaction. Transaction rules also apply to extension calls.
  ///
  /// Success contains the serialized protobuf response message. Failure contains the serialized
  /// `spatialengine.v1.std.StatementError` message. Generate protobuf bindings to decode either arm.
  execute-statement: func(
    path: string,
    payload: list<u8>,
    transaction-id: option<string>,
  ) -> result<list<u8>, list<u8>>;
}

world extension {
  /// The host provides this interface when it instantiates the component.
  import engine;
  /// The engine invokes this entrypoint to execute the extension's workflow.
  export run: func();
}