Add attribute typings for agent and transcription (#811)

Introduces a new file `attribute-typings.dart` defining Dart classes and enums for agent and transcription attributes, including JSON serialization helpers. Also exports this new typings file from the main library entry point.

Author: hiroshihorie

lib/livekit_client.dart

@@ -44,8 +44,7 @@ export 'src/track/local/local.dart';
 export 'src/track/local/video.dart';
 export 'src/track/options.dart';
 export 'src/track/processor.dart';
-export 'src/track/processor_native.dart'
-    if (dart.library.js_interop) 'src/track/processor_web.dart';
+export 'src/track/processor_native.dart' if (dart.library.js_interop) 'src/track/processor_web.dart';
 export 'src/track/remote/audio.dart';
 export 'src/track/remote/remote.dart';
 export 'src/track/remote/video.dart';
@@ -60,3 +59,4 @@ export 'src/types/video_encoding.dart';
 export 'src/types/video_parameters.dart';
 export 'src/widgets/screen_select_dialog.dart';
 export 'src/widgets/video_track_renderer.dart';
+export 'src/types/attribute-typings.dart';

lib/src/types/attribute-typings.dart

@@ -0,0 +1,109 @@
+// To parse this JSON data, do
+//
+//     final agentAttributes = agentAttributesFromJson(jsonString);
+//     final transcriptionAttributes = transcriptionAttributesFromJson(jsonString);
+
+import 'dart:convert';
+
+AgentAttributes agentAttributesFromJson(String str) => AgentAttributes.fromJson(json.decode(str));
+
+String agentAttributesToJson(AgentAttributes data) => json.encode(data.toJson());
+
+TranscriptionAttributes transcriptionAttributesFromJson(String str) =>
+    TranscriptionAttributes.fromJson(json.decode(str));
+
+String transcriptionAttributesToJson(TranscriptionAttributes data) => json.encode(data.toJson());
+
+class AgentAttributes {
+  List<AgentInput>? lkAgentInputs;
+  List<AgentOutput>? lkAgentOutputs;
+  AgentState? lkAgentState;
+  String? lkPublishOnBehalf;
+
+  AgentAttributes({
+    this.lkAgentInputs,
+    this.lkAgentOutputs,
+    this.lkAgentState,
+    this.lkPublishOnBehalf,
+  });
+
+  factory AgentAttributes.fromJson(Map<String, dynamic> json) => AgentAttributes(
+        lkAgentInputs: json['lk.agent.inputs'] == null
+            ? []
+            : List<AgentInput>.from(json['lk.agent.inputs']!.map((x) => agentInputValues.map[x]!)),
+        lkAgentOutputs: json['lk.agent.outputs'] == null
+            ? []
+            : List<AgentOutput>.from(json['lk.agent.outputs']!.map((x) => agentOutputValues.map[x]!)),
+        lkAgentState: agentStateValues.map[json['lk.agent.state']]!,
+        lkPublishOnBehalf: json['lk.publish_on_behalf'],
+      );
+
+  Map<String, dynamic> toJson() => {
+        'lk.agent.inputs':
+            lkAgentInputs == null ? [] : List<dynamic>.from(lkAgentInputs!.map((x) => agentInputValues.reverse[x])),
+        'lk.agent.outputs':
+            lkAgentOutputs == null ? [] : List<dynamic>.from(lkAgentOutputs!.map((x) => agentOutputValues.reverse[x])),
+        'lk.agent.state': agentStateValues.reverse[lkAgentState],
+        'lk.publish_on_behalf': lkPublishOnBehalf,
+      };
+}
+
+enum AgentInput { AUDIO, TEXT, VIDEO }
+
+final agentInputValues = EnumValues({'audio': AgentInput.AUDIO, 'text': AgentInput.TEXT, 'video': AgentInput.VIDEO});
+
+enum AgentOutput { AUDIO, TRANSCRIPTION }
+
+final agentOutputValues = EnumValues({'audio': AgentOutput.AUDIO, 'transcription': AgentOutput.TRANSCRIPTION});
+
+enum AgentState { IDLE, INITIALIZING, LISTENING, SPEAKING, THINKING }
+
+final agentStateValues = EnumValues({
+  'idle': AgentState.IDLE,
+  'initializing': AgentState.INITIALIZING,
+  'listening': AgentState.LISTENING,
+  'speaking': AgentState.SPEAKING,
+  'thinking': AgentState.THINKING
+});
+
+///Schema for transcription-related attributes
+class TranscriptionAttributes {
+  ///The segment id of the transcription
+  String? lkSegmentId;
+
+  ///The associated track id of the transcription
+  String? lkTranscribedTrackId;
+
+  ///Whether the transcription is final
+  bool? lkTranscriptionFinal;
+
+  TranscriptionAttributes({
+    this.lkSegmentId,
+    this.lkTranscribedTrackId,
+    this.lkTranscriptionFinal,
+  });
+
+  factory TranscriptionAttributes.fromJson(Map<String, dynamic> json) => TranscriptionAttributes(
+        lkSegmentId: json['lk.segment_id'],
+        lkTranscribedTrackId: json['lk.transcribed_track_id'],
+        lkTranscriptionFinal: json['lk.transcription_final'],
+      );
+
+  Map<String, dynamic> toJson() => {
+        'lk.segment_id': lkSegmentId,
+        'lk.transcribed_track_id': lkTranscribedTrackId,
+        'lk.transcription_final': lkTranscriptionFinal,
+      };
+}
+
+class EnumValues<T> {
+  Map<String, T> map;
+  late Map<T, String> reverseMap;
+
+  EnumValues(this.map);
+
+  Map<T, String> get reverse {
+    reverseMap = map.map((k, v) => MapEntry(v, k));
+    return reverseMap;
+  }
+}