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/data/models/ag_ui_event.dart

@@ -1,3 +1,5 @@
+import 'dart:convert';
+
 import 'package:json_annotation/json_annotation.dart';
 import 'tool_result.dart';
 
@@ -15,6 +17,7 @@ class AgUiEventTypeWire {
   static const toolCallEnd = 'TOOL_CALL_END';
   static const toolCallResult = 'TOOL_CALL_RESULT';
   static const toolCallError = 'TOOL_CALL_ERROR';
+  static const stateSnapshot = 'STATE_SNAPSHOT';
   static const messagesSnapshot = 'MESSAGES_SNAPSHOT';
 }
 
@@ -30,6 +33,7 @@ enum AgUiEventType {
   toolCallEnd,
   toolCallResult,
   toolCallError,
+  stateSnapshot,
   messagesSnapshot,
   unknown,
 }
@@ -47,6 +51,7 @@ const _wireToTypeMap = {
   AgUiEventTypeWire.toolCallEnd: AgUiEventType.toolCallEnd,
   AgUiEventTypeWire.toolCallResult: AgUiEventType.toolCallResult,
   AgUiEventTypeWire.toolCallError: AgUiEventType.toolCallError,
+  AgUiEventTypeWire.stateSnapshot: AgUiEventType.stateSnapshot,
   AgUiEventTypeWire.messagesSnapshot: AgUiEventType.messagesSnapshot,
 };
 
@@ -63,6 +68,7 @@ const _typeToWireMap = {
   AgUiEventType.toolCallEnd: AgUiEventTypeWire.toolCallEnd,
   AgUiEventType.toolCallResult: AgUiEventTypeWire.toolCallResult,
   AgUiEventType.toolCallError: AgUiEventTypeWire.toolCallError,
+  AgUiEventType.stateSnapshot: AgUiEventTypeWire.stateSnapshot,
   AgUiEventType.messagesSnapshot: AgUiEventTypeWire.messagesSnapshot,
   AgUiEventType.unknown: '',
 };
@@ -85,6 +91,7 @@ final _typeToFactory = {
   AgUiEventType.toolCallEnd: ToolCallEndEvent.fromJson,
   AgUiEventType.toolCallResult: ToolCallResultEvent.fromJson,
   AgUiEventType.toolCallError: ToolCallErrorEvent.fromJson,
+  AgUiEventType.stateSnapshot: StateSnapshotEvent.fromJson,
   AgUiEventType.messagesSnapshot: MessagesSnapshotEvent.fromJson,
   AgUiEventType.unknown: UnknownAgUiEvent.fromJson,
 };
@@ -255,25 +262,61 @@ class ToolCallEndEvent extends AgUiEvent {
   Map<String, dynamic> toJson() => _$ToolCallEndEventToJson(this);
 }
 
-@JsonSerializable()
+@JsonSerializable(createFactory: false, createToJson: false)
 class ToolCallResultEvent extends AgUiEvent {
   final String messageId;
   final String toolCallId;
-  final Map<String, dynamic> result;
-  final UiCard? ui;
+  final String content;
 
   ToolCallResultEvent({
     required this.messageId,
     required this.toolCallId,
-    required this.result,
-    this.ui,
+    required this.content,
   }) : super(type: AgUiEventType.toolCallResult);
 
-  factory ToolCallResultEvent.fromJson(Map<String, dynamic> json) =>
-      _$ToolCallResultEventFromJson(json);
+  Map<String, dynamic> get payload {
+    try {
+      final decoded = jsonDecode(content);
+      if (decoded is Map<String, dynamic>) {
+        return decoded;
+      }
+    } catch (_) {}
+    return {'content': content};
+  }
+
+  Map<String, dynamic> get result {
+    final rawResult = payload['result'];
+    if (rawResult is Map<String, dynamic>) {
+      return rawResult;
+    }
+    return payload;
+  }
+
+  UiCard? get ui {
+    final rawUi = payload['ui'];
+    if (rawUi is Map<String, dynamic>) {
+      return UiCard.fromJson(rawUi);
+    }
+    return null;
+  }
+
+  factory ToolCallResultEvent.fromJson(Map<String, dynamic> json) {
+    final rawContent = json['content'];
+    final content = rawContent is String ? rawContent : '';
+    return ToolCallResultEvent(
+      messageId: json['messageId'] as String,
+      toolCallId: json['toolCallId'] as String,
+      content: content,
+    );
+  }
 
   @override
-  Map<String, dynamic> toJson() => _$ToolCallResultEventToJson(this);
+  Map<String, dynamic> toJson() => {
+    'type': agUiEventTypeToWire(type),
+    'messageId': messageId,
+    'toolCallId': toolCallId,
+    'content': content,
+  };
 }
 
 @JsonSerializable()
@@ -292,6 +335,29 @@ class ToolCallErrorEvent extends AgUiEvent {
   Map<String, dynamic> toJson() => _$ToolCallErrorEventToJson(this);
 }
 
+@JsonSerializable(createFactory: false, createToJson: false)
+class StateSnapshotEvent extends AgUiEvent {
+  final Map<String, dynamic> snapshot;
+
+  StateSnapshotEvent({required this.snapshot})
+    : super(type: AgUiEventType.stateSnapshot);
+
+  factory StateSnapshotEvent.fromJson(Map<String, dynamic> json) {
+    final rawSnapshot = json['snapshot'];
+    return StateSnapshotEvent(
+      snapshot: rawSnapshot is Map<String, dynamic>
+          ? rawSnapshot
+          : <String, dynamic>{},
+    );
+  }
+
+  @override
+  Map<String, dynamic> toJson() => {
+    'type': agUiEventTypeToWire(type),
+    'snapshot': snapshot,
+  };
+}
+
 @JsonSerializable()
 class MessagesSnapshotEvent extends AgUiEvent {
   final List<SnapshotMessage> messages;

apps/lib/features/chat/data/models/ag_ui_event.g.dart

@@ -121,10 +121,7 @@ ToolCallResultEvent _$ToolCallResultEventFromJson(Map<String, dynamic> json) =>
     ToolCallResultEvent(
       messageId: json['messageId'] as String,
       toolCallId: json['toolCallId'] as String,
-      result: json['result'] as Map<String, dynamic>,
-      ui: json['ui'] == null
-          ? null
-          : UiCard.fromJson(json['ui'] as Map<String, dynamic>),
+      content: json['content'] as String,
     );
 
 Map<String, dynamic> _$ToolCallResultEventToJson(
@@ -132,8 +129,7 @@ Map<String, dynamic> _$ToolCallResultEventToJson(
 ) => <String, dynamic>{
   'messageId': instance.messageId,
   'toolCallId': instance.toolCallId,
-  'result': instance.result,
-  'ui': instance.ui,
+  'content': instance.content,
 };
 
 ToolCallErrorEvent _$ToolCallErrorEventFromJson(Map<String, dynamic> json) =>