feat: 支持 agent 运行取消功能

apps/lib/features/chat/data/services/ag_ui_service.dart

@@ -50,6 +50,8 @@ class AgUiService {
   Completer<void>? _activeSseDoneCompleter;
 
   String? _threadId;
+  String? _activeThreadIdForRun;
+  String? _activeRunId;
   bool _hasMoreHistory = false;
 
   AgUiService({EventCallback? onEvent, required IApiClient apiClient})
@@ -83,11 +85,20 @@ class AgUiService {
       throw StateError('Missing runId in /agent/runs response');
     }
     _threadId = threadId;
-    await _streamEventsFromApi(
-      threadId,
-      expectedRunId: runId,
-      streamToken: streamToken,
-    );
+    _activeThreadIdForRun = threadId;
+    _activeRunId = runId;
+    try {
+      await _streamEventsFromApi(
+        threadId,
+        expectedRunId: runId,
+        streamToken: streamToken,
+      );
+    } finally {
+      if (_activeThreadIdForRun == threadId && _activeRunId == runId) {
+        _activeThreadIdForRun = null;
+        _activeRunId = null;
+      }
+    }
     return SendMessageResult(
       uploadedAttachments: runInputPayload.uploadedAttachments,
     );
@@ -151,6 +162,19 @@ class AgUiService {
   }
 
   Future<void> cancelCurrentRun() async {
+    final activeThreadId = _activeThreadIdForRun;
+    final activeRunId = _activeRunId;
+    if (activeThreadId != null && activeRunId != null) {
+      final encodedRunId = Uri.encodeQueryComponent(activeRunId);
+      await _apiClient.post<Map<String, dynamic>>(
+        '/api/v1/agent/runs/$activeThreadId/cancel?runId=$encodedRunId',
+      );
+      _activeThreadIdForRun = null;
+      _activeRunId = null;
+      _activeStreamToken += 1;
+      await _cancelActiveSseSubscription();
+      return;
+    }
     _activeStreamToken += 1;
     await _cancelActiveSseSubscription();
   }