refactor: fethcer interface & download flow (#1229)

ui/flutter/lib/api/model/resolve_task.dart

@@ -0,0 +1,21 @@
+import 'package:json_annotation/json_annotation.dart';
+
+import 'options.dart';
+import 'request.dart';
+
+part 'resolve_task.g.dart';
+
+@JsonSerializable()
+class ResolveTask {
+  Request? req;
+  Options? opts;
+
+  ResolveTask({
+    this.req,
+    this.opts,
+  });
+
+  factory ResolveTask.fromJson(Map<String, dynamic> json) =>
+      _$ResolveTaskFromJson(json);
+  Map<String, dynamic> toJson() => _$ResolveTaskToJson(this);
+}