feat: 优化 Agent 运行时与聊天设置体验

apps/test/features/chat/ag_ui_event_test.dart

@@ -87,5 +87,32 @@ void main() {
       expect(snapshot.messages, hasLength(1));
       expect(snapshot.messages.first.uiSchema, isNotNull);
     });
+
+    test('parses history user attachments list', () {
+      final snapshot = HistorySnapshot.fromJson({
+        'scope': 'history_day',
+        'threadId': 'thread_1',
+        'day': '2026-03-16',
+        'hasMore': false,
+        'messages': [
+          {
+            'id': 'm1',
+            'seq': 1,
+            'role': 'user',
+            'content': '请看图',
+            'attachments': [
+              {'url': 'https://signed.example/a.png', 'mimeType': 'image/png'},
+              {'url': 'https://signed.example/b.jpg', 'mimeType': 'image/jpeg'},
+            ],
+            'timestamp': '2026-03-16T10:00:00Z',
+          },
+        ],
+      });
+
+      final userMessage = snapshot.messages.first;
+      expect(userMessage.attachments, hasLength(2));
+      expect(userMessage.attachments.first.url, 'https://signed.example/a.png');
+      expect(userMessage.attachments.last.mimeType, 'image/jpeg');
+    });
   });
 }

apps/test/features/chat/presentation/agent_stage_mapping_test.dart

@@ -0,0 +1,27 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:social_app/features/chat/presentation/bloc/agent_stage.dart';
+
+void main() {
+  group('agent stage mapping', () {
+    test('maps protocol step router to intent stage label', () {
+      final stage = stageFromStepName('router');
+
+      expect(stage, AgentStage.intent);
+      expect(stageLabel(stage), '意图识别中');
+    });
+
+    test('maps protocol step worker to execution stage label', () {
+      final stage = stageFromStepName('worker');
+
+      expect(stage, AgentStage.execution);
+      expect(stageLabel(stage), '任务执行中');
+    });
+
+    test('uses processing label when step is unknown', () {
+      final stage = stageFromStepName('unexpected');
+
+      expect(stage, isNull);
+      expect(stageLabel(stage), '任务处理中');
+    });
+  });
+}