feat: 支持 agent 运行取消功能

apps/lib/features/chat/presentation/bloc/chat_bloc.dart

@@ -123,10 +123,16 @@ class ChatBloc extends Cubit<ChatState> {
         );
       case AgUiEventType.runError:
         final errorEvent = event as RunErrorEvent;
+        final isCanceledByUser = errorEvent.code == 'RUN_CANCELED';
         emit(
           _resetRunState(
-            error: errorEvent.message,
-          ).copyWith(items: _markActiveToolCallsFailed(state.items)),
+            error: isCanceledByUser ? null : errorEvent.message,
+          ).copyWith(
+            items: _markActiveToolCallsFailed(
+              state.items,
+              reason: isCanceledByUser ? '本次运行已取消' : '本次运行已失败',
+            ),
+          ),
         );
       case AgUiEventType.stepStarted:
         _handleStepStarted(event as StepStartedEvent);
@@ -286,7 +292,10 @@ class ChatBloc extends Cubit<ChatState> {
     return items.where((item) => item is! ToolCallItem).toList();
   }
 
-  List<ChatListItem> _markActiveToolCallsFailed(List<ChatListItem> items) {
+  List<ChatListItem> _markActiveToolCallsFailed(
+    List<ChatListItem> items, {
+    required String reason,
+  }) {
     return items.map((item) {
       if (item is! ToolCallItem) {
         return item;
@@ -297,10 +306,7 @@ class ChatBloc extends Cubit<ChatState> {
       if (item.status == ToolCallStatus.completed) {
         return item;
       }
-      return item.copyWith(
-        status: ToolCallStatus.error,
-        errorMessage: '本次运行已失败',
-      );
+      return item.copyWith(status: ToolCallStatus.error, errorMessage: reason);
     }).toList();
   }