refactor(apps): 主题系统迁移至 ColorScheme + 扩展架构并支持 Dark Mode

apps/lib/core/chat/agent_stage.dart

@@ -0,0 +1,25 @@
+import '../l10n/l10n.dart';
+
+enum AgentStage { routing, execution, memory }
+
+AgentStage? stageFromStepName(String value) {
+  switch (value) {
+    case 'router':
+      return AgentStage.routing;
+    case 'worker':
+      return AgentStage.execution;
+    case 'memory':
+      return AgentStage.memory;
+    default:
+      return null;
+  }
+}
+
+String stageLabel(AgentStage? stage) {
+  return switch (stage) {
+    AgentStage.routing => L10n.current.agentStageRouting,
+    AgentStage.execution => L10n.current.agentStageExecution,
+    AgentStage.memory => L10n.current.agentStageMemory,
+    null => L10n.current.agentStageProcessing,
+  };
+}

apps/lib/core/chat/chat_list_item.dart

@@ -0,0 +1,122 @@
+enum ChatItemType { message, toolCall, toolResult }
+
+enum MessageSender { user, ai }
+
+enum ToolCallStatus { pending, executing, completed, error }
+
+abstract class ChatListItem {
+  String get id;
+  DateTime get timestamp;
+  ChatItemType get type;
+  MessageSender get sender;
+}
+
+class TextMessageItem extends ChatListItem {
+  @override
+  final String id;
+  final String content;
+  @override
+  final DateTime timestamp;
+  @override
+  final MessageSender sender;
+  final bool isStreaming;
+  final List<Map<String, dynamic>> attachments;
+
+  TextMessageItem({
+    required this.id,
+    required this.content,
+    required this.timestamp,
+    required this.sender,
+    this.isStreaming = false,
+    this.attachments = const [],
+  });
+
+  @override
+  ChatItemType get type => ChatItemType.message;
+
+  TextMessageItem copyWith({
+    String? id,
+    String? content,
+    DateTime? timestamp,
+    MessageSender? sender,
+    bool? isStreaming,
+    List<Map<String, dynamic>>? attachments,
+  }) => TextMessageItem(
+    id: id ?? this.id,
+    content: content ?? this.content,
+    timestamp: timestamp ?? this.timestamp,
+    sender: sender ?? this.sender,
+    isStreaming: isStreaming ?? this.isStreaming,
+    attachments: attachments ?? this.attachments,
+  );
+}
+
+class ToolCallItem extends ChatListItem {
+  @override
+  final String id;
+  final String callId;
+  final String toolName;
+  final Map<String, dynamic> args;
+  final ToolCallStatus status;
+  final String? errorMessage;
+  @override
+  final DateTime timestamp;
+  @override
+  final MessageSender sender;
+
+  ToolCallItem({
+    required this.id,
+    required this.callId,
+    required this.toolName,
+    required this.args,
+    required this.status,
+    this.errorMessage,
+    required this.timestamp,
+    required this.sender,
+  });
+
+  @override
+  ChatItemType get type => ChatItemType.toolCall;
+
+  ToolCallItem copyWith({
+    String? id,
+    String? callId,
+    String? toolName,
+    Map<String, dynamic>? args,
+    ToolCallStatus? status,
+    String? errorMessage,
+    DateTime? timestamp,
+    MessageSender? sender,
+  }) => ToolCallItem(
+    id: id ?? this.id,
+    callId: callId ?? this.callId,
+    toolName: toolName ?? this.toolName,
+    args: args ?? this.args,
+    status: status ?? this.status,
+    errorMessage: errorMessage ?? this.errorMessage,
+    timestamp: timestamp ?? this.timestamp,
+    sender: sender ?? this.sender,
+  );
+}
+
+class ToolResultItem extends ChatListItem {
+  @override
+  final String id;
+  final String callId;
+  final Map<String, dynamic> uiSchema;
+  @override
+  final DateTime timestamp;
+  @override
+  final MessageSender sender;
+
+  ToolResultItem({
+    required this.id,
+    required this.callId,
+    required this.uiSchema,
+    required this.timestamp,
+    required this.sender,
+  });
+
+  @override
+  ChatItemType get type => ChatItemType.toolResult;
+}

apps/lib/core/chat/chat_orchestrator.dart

@@ -0,0 +1,31 @@
+import 'package:image_picker/image_picker.dart';
+
+import 'agent_stage.dart';
+import 'chat_list_item.dart';
+
+abstract class ChatOrchestratorState {
+  List<ChatListItem> get items;
+  bool get isSending;
+  bool get isWaitingFirstToken;
+  bool get isStreaming;
+  bool get isCancelling;
+  bool get isLoadingHistory;
+  String? get currentMessageId;
+  String? get error;
+  DateTime? get oldestLoadedDate;
+  bool get hasEarlierHistory;
+  AgentStage? get currentStage;
+  bool get isLoading;
+}
+
+abstract class ChatOrchestrator {
+  ChatOrchestratorState get state;
+  Stream<ChatOrchestratorState> get stream;
+
+  Future<void> sendMessage(String content, {List<XFile>? images});
+  Future<void> loadHistory();
+  Future<void> loadMoreHistory();
+  Future<String> transcribeAudioFile(String filePath);
+  Future<bool> cancelCurrentRun();
+  void clearError();
+}