Update lint package & rules (#869)

* Updated lints package to 6.0.0.
* New rules: `discarded_futures` & `prefer_final_locals`.
* Did some quick maintenance to some lint errors.

There's quite a few "disregarded futures" (Un-awaited Futures) we should
clean them up.

Author: hiroshihorie

analysis_options.yaml

@@ -1,4 +1,5 @@
-# Copyright 2024 LiveKit, Inc.
+#
+# Copyright 2025 LiveKit
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -12,34 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# This file configures the analyzer, which statically analyzes Dart code to
-# check for errors, warnings, and lints.
-#
-# The issues identified by the analyzer are surfaced in the UI of Dart-enabled
-# IDEs (https://dart.dev/tools#ides-and-editors). The analyzer can also be
-# invoked from the command line by running `flutter analyze`.
-
-# The following line activates a set of recommended lints for Flutter apps,
-# packages, and plugins designed to encourage good coding practices.
-
-# https://pub.dev/packages/flutter_lints
-
 include: package:lints/recommended.yaml
 
 analyzer:
   errors:
     constant_identifier_names: ignore
     no_wildcard_variable_uses: ignore
     use_super_parameters: ignore
-  #
-  # Enforce stricter type-checking
-  # https://dart.dev/guides/language/analysis-options#enabling-additional-type-checks
-  # https://dash-overflow.net/articles/getting_started/#step-3-disabling-_implicit-dynamic_--_implicit-cast_
-  #
 
-  #
-  # exclude protobuf files
-  #
+  # Exclude protobuf files
   exclude:
     - '**/*.pb.dart'
     - '**/*.pbenum.dart'
@@ -49,10 +31,11 @@ analyzer:
 
 linter:
   rules:
-    #
-    # Additional recommended rules
-    #
+    # Preference of the SDK
     prefer_single_quotes: true
+    prefer_final_locals: true
     unnecessary_brace_in_string_interps: false
+
+    # Enforce this for correct async logic
     unawaited_futures: true
-    depend_on_referenced_packages: false
+    discarded_futures: true

lib/livekit_client.dart

@@ -12,9 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-/// Flutter Client SDK to LiveKit.
-library livekit_client;
-
 export 'src/constants.dart';
 export 'src/core/room.dart';
 export 'src/data_stream/stream_reader.dart';

lib/src/core/engine.dart

@@ -336,7 +336,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
     final message =
         rtc.RTCDataChannelMessage.fromBinary(packet.writeToBuffer());
 
-    var reliabilityType =
+    final reliabilityType =
         reliability == true ? Reliability.reliable : Reliability.lossy;
 
     if (_subscriberPrimary) {
@@ -625,7 +625,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
   Future<void> _handleGettingConnectedServerAddress(
       rtc.RTCPeerConnection pc) async {
     try {
-      var remoteAddress = await getConnectedAddress(publisher!.pc);
+      final remoteAddress = await getConnectedAddress(publisher!.pc);
       logger.fine('Connected address: $remoteAddress');
       if (_connectedServerAddress == null ||
           _connectedServerAddress != remoteAddress) {
@@ -740,7 +740,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
       return;
     }
 
-    var delay = defaultRetryDelaysInMs[reconnectAttempts!];
+    final delay = defaultRetryDelaysInMs[reconnectAttempts!];
 
     events.emit(EngineAttemptReconnectEvent(
       attempt: reconnectAttempts! + 1,
@@ -965,7 +965,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
       // create peer connections
       _subscriberPrimary = event.response.subscriberPrimary;
       _serverInfo = event.response.serverInfo;
-      var iceServersFromServer =
+      final iceServersFromServer =
           event.response.iceServers.map((e) => e.toSDKType()).toList();
 
       if (iceServersFromServer.isNotEmpty) {
@@ -979,7 +979,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
           'iceServers: ${event.response.iceServers}, '
           'forceRelay: $event.response.clientConfiguration.forceRelay');
 
-      var rtcConfiguration = await _buildRtcConfiguration(
+      final rtcConfiguration = await _buildRtcConfiguration(
           serverResponseForceRelay:
               event.response.clientConfiguration.forceRelay,
           serverProvidedIceServers: _serverProvidedIceServers);
@@ -1000,7 +1000,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
       events.emit(EngineJoinResponseEvent(response: event.response));
     })
     ..on<SignalReconnectResponseEvent>((event) async {
-      var iceServersFromServer =
+      final iceServersFromServer =
           event.response.iceServers.map((e) => e.toSDKType()).toList();
 
       if (iceServersFromServer.isNotEmpty) {
@@ -1013,7 +1013,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
           'iceServers: ${event.response.iceServers}, '
           'forceRelay: $event.response.clientConfiguration.forceRelay');
 
-      var rtcConfiguration = await _buildRtcConfiguration(
+      final rtcConfiguration = await _buildRtcConfiguration(
           serverResponseForceRelay:
               event.response.clientConfiguration.forceRelay,
           serverProvidedIceServers: _serverProvidedIceServers);
@@ -1055,7 +1055,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
         logger.warning('[$objectId] subscriber is null');
         return;
       }
-      var signalingState = await subscriber!.pc.getSignalingState();
+      final signalingState = await subscriber!.pc.getSignalingState();
       logger.fine('[$objectId] Received server offer(type: ${event.sd.type}, '
           '$signalingState)');
       logger.finer('sdp: ${event.sd.sdp}');
@@ -1182,7 +1182,7 @@ extension EngineInternalMethods on Engine {
     if (track.mediaStreamTrack.kind == 'video' && opts is VideoPublishOptions) {
       track.codec = opts.videoCodec;
     }
-    var transceiverInit = rtc.RTCRtpTransceiverInit(
+    final transceiverInit = rtc.RTCRtpTransceiverInit(
       direction: rtc.TransceiverDirection.SendOnly,
     );
     if (encodings != null) {
@@ -1215,7 +1215,7 @@ extension EngineInternalMethods on Engine {
     if (publisher == null) {
       throw Exception('publisher is closed');
     }
-    var transceiverInit = rtc.RTCRtpTransceiverInit(
+    final transceiverInit = rtc.RTCRtpTransceiverInit(
       direction: rtc.TransceiverDirection.SendOnly,
     );
     if (encodings != null) {
@@ -1235,22 +1235,22 @@ extension EngineInternalMethods on Engine {
       rtc.RTCRtpTransceiver transceiver, String kind, String videoCodec) async {
     // when setting codec preferences, the capabilites need to be read from
     // the RTCRtpReceiver
-    var caps = await rtc.getRtpReceiverCapabilities(kind);
+    final caps = await rtc.getRtpReceiverCapabilities(kind);
     if (caps.codecs == null) return;
 
     logger.fine('get capabilities ${caps.codecs}');
 
-    List<rtc.RTCRtpCodecCapability> matched = [];
-    List<rtc.RTCRtpCodecCapability> partialMatched = [];
-    List<rtc.RTCRtpCodecCapability> unmatched = [];
+    final List<rtc.RTCRtpCodecCapability> matched = [];
+    final List<rtc.RTCRtpCodecCapability> partialMatched = [];
+    final List<rtc.RTCRtpCodecCapability> unmatched = [];
     for (var c in caps.codecs!) {
-      var codec = c.mimeType.toLowerCase();
+      final codec = c.mimeType.toLowerCase();
       if (codec == 'audio/opus') {
         matched.add(c);
         continue;
       }
 
-      var matchesVideoCodec = codec == 'video/$videoCodec';
+      final matchesVideoCodec = codec == 'video/$videoCodec';
       if (!matchesVideoCodec) {
         if (lkPlatformIs(PlatformType.android) && codec == 'video/vp9') {
           if (c.sdpFmtpLine != null &&

lib/src/core/room.dart

@@ -338,7 +338,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
         if (publication.track! is! LocalVideoTrack) {
           return;
         }
-        var videoTrack = publication.track as LocalVideoTrack;
+        final videoTrack = publication.track as LocalVideoTrack;
         final newCodecs = await videoTrack.setPublishingCodecs(
             event.subscribedCodecs, videoTrack);
         for (var codec in newCodecs) {
@@ -350,7 +350,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
           }
         }
       } else if (event.subscribedQualities.isNotEmpty) {
-        var videoTrack = publication.track as LocalVideoTrack;
+        final videoTrack = publication.track as LocalVideoTrack;
         await videoTrack.updatePublishingLayers(
             videoTrack, event.subscribedQualities);
       }
@@ -413,7 +413,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
     });
 
   void _setUpEngineListeners() => _engineListener
-    ..on<EngineJoinResponseEvent>((event) {
+    ..on<EngineJoinResponseEvent>((event) async {
       _roomInfo = event.response.room;
       _name = event.response.room.name;
       _metadata = event.response.room.metadata;
@@ -435,47 +435,47 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
       );
 
       if (engine.fullReconnectOnNext) {
-        _localParticipant!.updateFromInfo(event.response.participant);
+        await _localParticipant!.updateFromInfo(event.response.participant);
       }
 
       if (connectOptions.protocolVersion.index >= ProtocolVersion.v8.index &&
           engine.fastConnectOptions != null &&
           !engine.fullReconnectOnNext) {
-        var options = engine.fastConnectOptions!;
+        final options = engine.fastConnectOptions!;
 
-        var audio = options.microphone;
-        bool audioEnabled = audio.enabled == true || audio.track != null;
+        final audio = options.microphone;
+        final bool audioEnabled = audio.enabled == true || audio.track != null;
         if (audioEnabled) {
           if (audio.track != null) {
-            _localParticipant!.publishAudioTrack(audio.track as LocalAudioTrack,
+            await _localParticipant!.publishAudioTrack(audio.track as LocalAudioTrack,
                 publishOptions: roomOptions.defaultAudioPublishOptions);
           } else {
-            _localParticipant!.setMicrophoneEnabled(true,
+            await _localParticipant!.setMicrophoneEnabled(true,
                 audioCaptureOptions: roomOptions.defaultAudioCaptureOptions);
           }
         }
 
-        var video = options.camera;
-        bool videoEnabled = video.enabled == true || video.track != null;
+        final video = options.camera;
+        final bool videoEnabled = video.enabled == true || video.track != null;
         if (videoEnabled) {
           if (video.track != null) {
-            _localParticipant!.publishVideoTrack(video.track as LocalVideoTrack,
+            await _localParticipant!.publishVideoTrack(video.track as LocalVideoTrack,
                 publishOptions: roomOptions.defaultVideoPublishOptions);
           } else {
-            _localParticipant!.setCameraEnabled(true,
+            await _localParticipant!.setCameraEnabled(true,
                 cameraCaptureOptions: roomOptions.defaultCameraCaptureOptions);
           }
         }
 
-        var screen = options.screen;
-        bool screenEnabled = screen.enabled == true || screen.track != null;
+        final screen = options.screen;
+        final bool screenEnabled = screen.enabled == true || screen.track != null;
         if (screenEnabled) {
           if (screen.track != null) {
-            _localParticipant!.publishVideoTrack(
+            await _localParticipant!.publishVideoTrack(
                 screen.track as LocalVideoTrack,
                 publishOptions: roomOptions.defaultVideoPublishOptions);
           } else {
-            _localParticipant!.setScreenShareEnabled(true,
+            await _localParticipant!.setScreenShareEnabled(true,
                 screenShareCaptureOptions:
                     roomOptions.defaultScreenShareCaptureOptions);
           }
@@ -490,7 +490,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
       }
 
       if (e2eeManager != null && event.response.sifTrailer.isNotEmpty) {
-        e2eeManager!.keyProvider
+        await e2eeManager!.keyProvider
             .setSifTrailer(Uint8List.fromList(event.response.sifTrailer));
       }
 
@@ -507,7 +507,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
       events.emit(const RoomReconnectingEvent());
 
       // clean up RemoteParticipants
-      var copy = _remoteParticipants.values.toList();
+      final copy = _remoteParticipants.values.toList();
 
       _remoteParticipants.clear();
       _sidToIdentity.clear();
@@ -581,7 +581,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
 
       final idParts = unpackStreamId(event.stream.id);
       final participantSid = idParts[0];
-      var streamId = idParts[1];
+      final streamId = idParts[1];
       var trackSid = event.track.id;
 
       // firefox will get streamId (pID|trackId) instead of (pID|streamId) as it doesn't support sync tracks by stream
@@ -624,7 +624,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
 
   /// Disconnects from the room, notifying server of disconnection.
   Future<void> disconnect() async {
-    bool isPendingReconnect = engine.isPendingReconnect;
+    final bool isPendingReconnect = engine.isPendingReconnect;
     if (engine.isClosed &&
         !isPendingReconnect &&
         engine.connectionState == ConnectionState.disconnected) {
@@ -766,7 +766,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
   // updates are sent only when there's a change to speaker ordering
   void _onEngineActiveSpeakersUpdateEvent(
       List<lk_models.SpeakerInfo> speakers) {
-    List<Participant> activeSpeakers = [];
+    final List<Participant> activeSpeakers = [];
 
     // localParticipant & remote participants
     final allParticipants = <String, Participant>{
@@ -816,7 +816,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
   void _onSignalStreamStateUpdateEvent(
       List<lk_rtc.StreamStateInfo> updates) async {
     for (final update in updates) {
-      var identity = _sidToIdentity[update.participantSid];
+      final identity = _sidToIdentity[update.participantSid];
       if (identity == null) {
         logger
             .warning('participant not found for sid ${update.participantSid}');
@@ -848,7 +848,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
     final publication =
         participant.getTrackPublicationBySid(event.transcription.trackId);
 
-    var segments = event.transcription.segments.map((segment) {
+    final segments = event.transcription.segments.map((segment) {
       return TranscriptionSegment(
         text: segment.text,
         id: segment.id,
@@ -941,7 +941,7 @@ extension RoomPrivateMethods on Room {
     logger.fine('[${objectId}] cleanUp()');
 
     // clean up RemoteParticipants
-    var participants = _remoteParticipants.values.toList();
+    final participants = _remoteParticipants.values.toList();
     for (final participant in participants) {
       await participant.removeAllPublishedTracks(notify: false);
       // RemoteParticipant is responsible for disposing resources
@@ -1153,7 +1153,7 @@ extension RoomHardwareManagementMethods on Room {
 
   Future<void> startAudio() async {
     try {
-      var audioContextRunning = await audio.startAllAudioElement();
+      final audioContextRunning = await audio.startAllAudioElement();
       if (audioContextRunning) {
         _handleAudioPlaybackStarted();
       } else {
@@ -1286,7 +1286,7 @@ extension DataStreamRoomMethods on Room {
         return;
       }
 
-      var info = ByteStreamInfo(
+      final info = ByteStreamInfo(
         id: streamHeader.streamId,
         name: streamHeader.byteHeader.name,
         mimeType: streamHeader.mimeType,
@@ -1298,7 +1298,7 @@ extension DataStreamRoomMethods on Room {
         attributes: streamHeader.attributes,
       );
 
-      var streamController = DataStreamController<lk_models.DataStream_Chunk>(
+      final streamController = DataStreamController<lk_models.DataStream_Chunk>(
         info: info,
         streamController: StreamController<lk_models.DataStream_Chunk>(),
         startTime: DateTime.timestamp().millisecondsSinceEpoch,
@@ -1320,7 +1320,7 @@ extension DataStreamRoomMethods on Room {
         return;
       }
 
-      var info = TextStreamInfo(
+      final info = TextStreamInfo(
         id: streamHeader.streamId,
         mimeType: streamHeader.mimeType,
         size: streamHeader.hasTotalLength()
@@ -1331,7 +1331,7 @@ extension DataStreamRoomMethods on Room {
         attributes: streamHeader.attributes,
       );
 
-      var streamController = DataStreamController<lk_models.DataStream_Chunk>(
+      final streamController = DataStreamController<lk_models.DataStream_Chunk>(
         info: info,
         streamController: StreamController<lk_models.DataStream_Chunk>(),
         startTime: DateTime.timestamp().millisecondsSinceEpoch,