refactor: improve type safety for isolates

common/lib/src/isolate/child/main.dart

@@ -22,7 +22,11 @@ class InitialData {
   });
 }
 
-/// A helper to setup the child isolate.
+/// A helper to setup the child isolate,
+/// constructing an endless running task that listens to [receiveFromMain]
+/// and calls [handler] for each message (usually calling [sendToMain] in the [handler]).
+///
+/// An optional [init] function can be provided to run before the endless loop.
 @internal
 Future<void> setupChildIsolateHelper<S, R>({
   required String debugLabel,

common/lib/src/isolate/child/multicast_discovery_isolate.dart

@@ -4,9 +4,17 @@ import 'package:common/src/isolate/child/main.dart';
 import 'package:common/src/isolate/dto/send_to_isolate_data.dart';
 import 'package:meta/meta.dart';
 
+/// Sends an announcement to all devices to all network interfaces.
+/// They will respond with their device information.
+class MulticastAnnouncementTask {
+  static const instance = MulticastAnnouncementTask._();
+
+  const MulticastAnnouncementTask._();
+}
+
 @internal
 Future<void> setupMulticastDiscoveryIsolate(
-  Stream<SendToIsolateData<void>> receiveFromMain,
+  Stream<SendToIsolateData<MulticastAnnouncementTask>> receiveFromMain,
   void Function(Device) sendToMain,
   InitialData initialData,
 ) async {

common/lib/src/isolate/parent/actions.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:common/model/device.dart';
 import 'package:common/src/isolate/child/http_scan_discovery_isolate.dart';
 import 'package:common/src/isolate/child/http_target_discovery_isolate.dart';
+import 'package:common/src/isolate/child/multicast_discovery_isolate.dart';
 import 'package:common/src/isolate/dto/isolate_task.dart';
 import 'package:common/src/isolate/dto/isolate_task_stream_result.dart';
 import 'package:common/src/isolate/dto/send_to_isolate_data.dart';
@@ -141,13 +142,15 @@ class IsolateSendMulticastAnnouncementAction extends ReduxAction<IsolateControll
 
     connection.sendToIsolate(SendToIsolateData(
       syncState: null,
-      data: const Object(),
+      data: MulticastAnnouncementTask.instance,
     ));
 
     return state;
   }
 }
 
+/// Sends the task to the isolate
+/// and transforms [IsolateTaskStreamResult] into a proper stream making it easier to work with.
 Stream<R> _sendTaskAndListenStream<R, T>({
   required IsolateTask<T> task,
   required IsolateConnector<IsolateTaskStreamResult<R>, SendToIsolateData<IsolateTask<T>>> connection,

common/lib/src/isolate/parent/parent_isolate_provider.dart

@@ -23,7 +23,7 @@ class ParentIsolateState with ParentIsolateStateMappable {
   final SyncState syncState;
   final IsolateConnector<IsolateTaskStreamResult<Device>, SendToIsolateData<IsolateTask<HttpScanTask>>>? httpScanDiscovery;
   final IsolateConnector<IsolateTaskResult<Device?>, SendToIsolateData<IsolateTask<HttpTargetTask>>>? httpTargetDiscovery;
-  final IsolateConnector<Device, SendToIsolateData<Object>>? multicastDiscovery;
+  final IsolateConnector<Device, SendToIsolateData<MulticastAnnouncementTask>>? multicastDiscovery;
 
   ParentIsolateState({
     required this.syncState,
@@ -81,7 +81,7 @@ class IsolateSetupAction extends AsyncReduxAction<IsolateController, ParentIsola
       ),
     );
 
-    final multicastDiscovery = await startIsolate<Device, SendToIsolateData<Object>, InitialData>(
+    final multicastDiscovery = await startIsolate<Device, SendToIsolateData<MulticastAnnouncementTask>, InitialData>(
       task: setupMulticastDiscoveryIsolate,
       param: InitialData(
         syncState: state.syncState,

common/lib/src/isolate/parent/parent_isolate_provider.mapper.dart

@@ -32,8 +32,8 @@ class ParentIsolateStateMapper extends ClassMapperBase<ParentIsolateState> {
       v.httpTargetDiscovery;
   static const Field<ParentIsolateState, IsolateConnector<IsolateTaskResult<Device?>, SendToIsolateData<IsolateTask<HttpTargetTask>>>>
       _f$httpTargetDiscovery = Field('httpTargetDiscovery', _$httpTargetDiscovery);
-  static IsolateConnector<Device, SendToIsolateData<Object>>? _$multicastDiscovery(ParentIsolateState v) => v.multicastDiscovery;
-  static const Field<ParentIsolateState, IsolateConnector<Device, SendToIsolateData<Object>>> _f$multicastDiscovery =
+  static IsolateConnector<Device, SendToIsolateData<MulticastAnnouncementTask>>? _$multicastDiscovery(ParentIsolateState v) => v.multicastDiscovery;
+  static const Field<ParentIsolateState, IsolateConnector<Device, SendToIsolateData<MulticastAnnouncementTask>>> _f$multicastDiscovery =
       Field('multicastDiscovery', _$multicastDiscovery);
 
   @override
@@ -102,7 +102,7 @@ abstract class ParentIsolateStateCopyWith<$R, $In extends ParentIsolateState, $O
       {SyncState? syncState,
       IsolateConnector<IsolateTaskStreamResult<Device>, SendToIsolateData<IsolateTask<HttpScanTask>>>? httpScanDiscovery,
       IsolateConnector<IsolateTaskResult<Device?>, SendToIsolateData<IsolateTask<HttpTargetTask>>>? httpTargetDiscovery,
-      IsolateConnector<Device, SendToIsolateData<Object>>? multicastDiscovery});
+      IsolateConnector<Device, SendToIsolateData<MulticastAnnouncementTask>>? multicastDiscovery});
   ParentIsolateStateCopyWith<$R2, $In, $Out2> $chain<$R2, $Out2>(Then<$Out2, $R2> t);
 }
 

common/lib/src/util/id_provider.dart

@@ -3,6 +3,7 @@ class IdProvider {
   int _id = 0;
 
   /// Returns the next id.
+  /// This is an atomic operation because Dart's event loop is single-threaded.
   int getNextId() => _id++;
 
   /// Resets the id to 0.

common/pubspec.yaml

@@ -4,7 +4,7 @@ version: 1.0.0
 publish_to: "none"
 
 environment:
-  sdk: ^3.1.1
+  sdk: ^3.5.0
 
 dependencies:
   collection: ^1.17.2 # allow newer versions, so it can compile with newer Flutter versions