feat: AG-UI 协议对齐与路由导航功能

- 前端: 添加 SSE 流式支持、stateSnapshot 事件、路由导航工具
- 前端: 实现工具调用审批流程，支持 pending 状态展示
- 后端: Agent 状态管理与会话持久化相关重构
- 文档: 新增 agent-agui-full-alignance 设计文档
- 测试: 补充相关单元测试和集成测试

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

@@ -1,6 +1,8 @@
 import 'dart:convert';
 
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:social_app/core/api/i_api_client.dart';
+import 'package:social_app/core/di/injection.dart';
 
 import '../../data/models/ag_ui_event.dart';
 import '../../data/models/chat_list_item.dart';
@@ -53,8 +55,9 @@ class ChatBloc extends Cubit<ChatState> {
   final AgUiService _service;
   final Map<String, String> _toolCallArgsBuffer = {};
 
-  ChatBloc({AgUiService? service})
-    : _service = service ?? AgUiService(),
+  ChatBloc({AgUiService? service, IApiClient? apiClient})
+    : _service =
+          service ?? AgUiService(apiClient: apiClient ?? sl<IApiClient>()),
       super(const ChatState()) {
     _service.onEvent = _handleEvent;
   }
@@ -84,6 +87,8 @@ class ChatBloc extends Cubit<ChatState> {
         _handleToolCallResult(event as ToolCallResultEvent);
       case AgUiEventType.toolCallError:
         _handleToolCallError(event as ToolCallErrorEvent);
+      case AgUiEventType.stateSnapshot:
+        _handleStateSnapshot(event as StateSnapshotEvent);
       case AgUiEventType.messagesSnapshot:
         _handleMessagesSnapshot(event as MessagesSnapshotEvent);
       case AgUiEventType.unknown:
@@ -157,9 +162,12 @@ class ChatBloc extends Cubit<ChatState> {
     _toolCallArgsBuffer.remove(endEvent.toolCallId);
     final updatedItems = state.items.map((item) {
       if (item.id == endEvent.toolCallId && item is ToolCallItem) {
+        final nextStatus = item.toolName == 'navigate_to_route'
+            ? ToolCallStatus.pending
+            : ToolCallStatus.executing;
         return item.copyWith(
           args: parsedArgs,
-          status: ToolCallStatus.executing,
+          status: nextStatus,
         );
       }
       return item;
@@ -174,10 +182,15 @@ class ChatBloc extends Cubit<ChatState> {
       }
       return true;
     }).toList();
+    final uiCard = resultEvent.ui;
+    if (uiCard == null) {
+      emit(state.copyWith(items: filteredItems));
+      return;
+    }
     final resultItem = ToolResultItem(
       id: resultEvent.messageId,
       callId: resultEvent.toolCallId,
-      uiCard: resultEvent.ui ?? UiCard(cardType: 'empty', data: {}),
+      uiCard: uiCard,
       timestamp: DateTime.now(),
       sender: MessageSender.ai,
     );
@@ -224,6 +237,26 @@ class ChatBloc extends Cubit<ChatState> {
     );
   }
 
+  void _handleStateSnapshot(StateSnapshotEvent stateSnapshotEvent) {
+    final snapshot = stateSnapshotEvent.snapshot;
+    if (snapshot['scope'] != 'history_day') {
+      return;
+    }
+    final rawMessages = snapshot['messages'];
+    if (rawMessages is! List<dynamic>) {
+      _handleMessagesSnapshot(MessagesSnapshotEvent(messages: const []));
+      return;
+    }
+    final parsed = <SnapshotMessage>[];
+    for (final raw in rawMessages) {
+      if (raw is! Map<String, dynamic>) {
+        continue;
+      }
+      parsed.add(SnapshotMessage.fromJson(raw));
+    }
+    _handleMessagesSnapshot(MessagesSnapshotEvent(messages: parsed));
+  }
+
   List<ChatListItem> _convertSnapshotMessages(List<SnapshotMessage> messages) {
     return messages.map((msg) {
       final timestamp = msg.timestamp ?? DateTime.now();
@@ -298,6 +331,44 @@ class ChatBloc extends Cubit<ChatState> {
     await _service.loadHistory(beforeDate: state.oldestLoadedDate);
   }
 
+  Future<void> approveToolCall(String toolCallId) async {
+    ToolCallItem? target;
+    for (final item in state.items) {
+      if (item is ToolCallItem && item.callId == toolCallId) {
+        target = item;
+        break;
+      }
+    }
+    if (target == null) {
+      return;
+    }
+    final updatedItems = state.items.map((item) {
+      if (item is ToolCallItem && item.callId == toolCallId) {
+        return item.copyWith(status: ToolCallStatus.executing, errorMessage: null);
+      }
+      return item;
+    }).toList();
+    emit(state.copyWith(items: updatedItems, isLoading: true, error: null));
+    try {
+      await _service.approveToolCall(
+        toolCallId: target.callId,
+        toolName: target.toolName,
+        args: target.args,
+      );
+    } catch (error) {
+      final failedItems = state.items.map((item) {
+        if (item is ToolCallItem && item.callId == toolCallId) {
+          return item.copyWith(
+            status: ToolCallStatus.error,
+            errorMessage: error.toString(),
+          );
+        }
+        return item;
+      }).toList();
+      emit(state.copyWith(items: failedItems, isLoading: false, error: error.toString()));
+    }
+  }
+
   void clearError() {
     emit(state.copyWith(error: null));
   }