feat(n8n-runner): support async response handling (#2487)

* feat(n8n-runner): support async response handling

* fix(n8n-runner): expose response handling in form

* fix(n8n-runner): preserve async response semantics

---------

Co-authored-by: dadachann <185672915+dadachann@users.noreply.github.com>

src/langbot/pkg/provider/runners/n8nsvapi.py

@@ -39,6 +39,9 @@ class N8nServiceAPIRunner(runner.RequestRunner):
 
         # 获取输出键名，默认为response
         self.output_key = self.pipeline_config['ai']['n8n-service-api'].get('output-key', 'response')
+        self.response_handling = self.pipeline_config['ai']['n8n-service-api'].get('response-handling', 'reply')
+        if self.response_handling not in {'reply', 'ignore'}:
+            raise ValueError(f'Invalid n8n response-handling: {self.response_handling}')
 
         # 获取认证类型，默认为none
         self.auth_type = self.pipeline_config['ai']['n8n-service-api'].get('auth-type', 'none')
@@ -262,7 +265,11 @@ class N8nServiceAPIRunner(runner.RequestRunner):
             async with session.post(
                 self.webhook_url, json=payload, headers=headers, auth=auth, timeout=self.timeout
             ) as response:
-                if response.status != 200:
+                if self.response_handling == 'ignore':
+                    status_ok = 200 <= response.status < 300
+                else:
+                    status_ok = response.status == 200
+                if not status_ok:
                     error_text = (
                         await httpclient.read_limited(
                             response,
@@ -272,6 +279,11 @@ class N8nServiceAPIRunner(runner.RequestRunner):
                     self.ap.logger.error(f'n8n webhook call failed: {response.status}, {error_text}')
                     raise Exception(f'n8n webhook call failed: {response.status}, {error_text}')
 
+                if self.response_handling == 'ignore':
+                    response.release()
+                    self.ap.logger.debug('n8n async webhook accepted; response body ignored')
+                    return
+
                 async for chunk in self._process_response(response):
                     if is_stream:
                         yield chunk

src/langbot/templates/default-pipeline-config.json

@@ -80,7 +80,8 @@
             "header-name": "",
             "header-value": "",
             "timeout": 120,
-            "output-key": "response"
+            "output-key": "response",
+            "response-handling": "reply"
         },
         "langflow-api": {
             "base-url": "http://localhost:7860",

src/langbot/templates/metadata/pipeline/ai.yaml

@@ -475,6 +475,25 @@ stages:
         type: string
         required: false
         default: 'response'
+      - name: response-handling
+        label:
+          en_US: Webhook Response Handling
+          zh_Hans: Webhook 响应处理方式
+        description:
+          en_US: Choose whether LangBot forwards the n8n webhook response to the chat user. Ignore mode requires the n8n Webhook node to use Respond Immediately.
+          zh_Hans: 选择是否将 n8n Webhook 响应转发给聊天用户。忽略模式要求 n8n Webhook 节点使用“立即响应”。
+        type: select
+        required: false
+        default: 'reply'
+        options:
+          - name: reply
+            label:
+              en_US: Forward as chat reply
+              zh_Hans: 转发为聊天回复
+          - name: ignore
+            label:
+              en_US: Ignore response body (asynchronous workflow)
+              zh_Hans: 忽略响应正文（异步工作流）
   - name: coze-api
     label:
       en_US: coze API