feat: 优化 Agent 运行时与聊天设置体验

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

@@ -308,7 +308,7 @@ class HistoryMessage {
     required this.role,
     required this.content,
     required this.timestamp,
-    this.url,
+    this.attachments = const <HistoryAttachment>[],
     this.uiSchema,
   });
 
@@ -317,7 +317,7 @@ class HistoryMessage {
   final String role;
   final String content;
   final DateTime timestamp;
-  final String? url;
+  final List<HistoryAttachment> attachments;
   final Map<String, dynamic>? uiSchema;
 
   factory HistoryMessage.fromJson(Map<String, dynamic> json) => HistoryMessage(
@@ -327,11 +327,25 @@ class HistoryMessage {
     content: _asString(json['content']),
     timestamp:
         DateTime.tryParse(_asString(json['timestamp'])) ?? DateTime.now(),
-    url: json['url'] as String?,
+    attachments: _parseHistoryAttachments(json['attachments']),
     uiSchema: _asMap(json['ui_schema']) ?? _asMap(json['uiSchema']),
   );
 }
 
+class HistoryAttachment {
+  const HistoryAttachment({required this.url, required this.mimeType});
+
+  final String url;
+  final String mimeType;
+
+  factory HistoryAttachment.fromJson(Map<String, dynamic> json) {
+    return HistoryAttachment(
+      url: _asString(json['url']),
+      mimeType: _asString(json['mimeType']),
+    );
+  }
+}
+
 String _asString(Object? value, {String fallback = ''}) {
   if (value is String) {
     return value;
@@ -368,3 +382,17 @@ Map<String, dynamic>? _asMap(Object? value) {
   }
   return null;
 }
+
+List<HistoryAttachment> _parseHistoryAttachments(Object? value) {
+  if (value is! List) {
+    return const <HistoryAttachment>[];
+  }
+  return value
+      .whereType<Map<String, dynamic>>()
+      .map(HistoryAttachment.fromJson)
+      .where(
+        (attachment) =>
+            attachment.url.isNotEmpty && attachment.mimeType.isNotEmpty,
+      )
+      .toList();
+}