Fix/Incomplete JSON data returned by N8N streaming data causes the loss of chunks. (#1880)

* fix: Incomplete JSON data returned by N8N streaming data causes the loss of chunks.

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

@@ -70,24 +70,78 @@ class N8nServiceAPIRunner(runner.RequestRunner):
 
     async def _process_stream_response(self, response: aiohttp.ClientResponse) -> typing.AsyncGenerator[
         provider_message.Message, None]:
-        """处理流式响应"""
+        """处理流式响应——支持部分 JSON 和多个 JSON 对象在同一 chunk 的情况"""
         full_content = ""
         chunk_idx = 0
         is_final = False
         message_idx = 0
-        async for chunk in response.content.iter_chunked(1024):
-            if not chunk:
+
+        buffer = ""
+        decoder = json.JSONDecoder()
+
+        async for raw_chunk in response.content.iter_chunked(1024):
+            if not raw_chunk:
                 continue
 
             try:
-                data = json.loads(chunk)
-                if data.get('type') == 'item' and 'content' in data:
-                    chunk_idx += 1
-                    content = data['content']
-                    full_content += content
-                elif data.get('type') == 'end':
-                    is_final = True
-                if is_final or chunk_idx % 8 == 0:
+                # 将 bytes 解码为字符串（容忍错误）
+                if isinstance(raw_chunk, (bytes, bytearray)):
+                    chunk_str = raw_chunk.decode('utf-8', errors='replace')
+                else:
+                    chunk_str = str(raw_chunk)
+
+                buffer += chunk_str
+
+                # 尝试从 buffer 中循环解析出 JSON 对象（处理多个对象或部分对象）
+                while buffer:
+                    buffer = buffer.lstrip()
+                    if not buffer:
+                        break
+                    try:
+                        obj, idx = decoder.raw_decode(buffer)
+                        buffer = buffer[idx:]
+
+                        if not isinstance(obj, dict):
+                            # 忽略非字典类型的顶级 JSON
+                            continue
+
+                        if obj.get('type') == 'item' and 'content' in obj:
+                            chunk_idx += 1
+                            content = obj['content']
+                            full_content += content
+                        elif obj.get('type') == 'end':
+                            is_final = True
+
+                        if is_final or chunk_idx % 8 == 0:
+                            message_idx += 1
+                            yield provider_message.MessageChunk(
+                                role='assistant',
+                                content=full_content,
+                                is_final=is_final,
+                                msg_sequence=message_idx,
+                            )
+                    except json.JSONDecodeError:
+                        # buffer 末尾可能是一个不完整的 JSON，等待更多数据
+                        break
+            except Exception as e:
+                # 记录解析失败并继续接收后续 chunk
+                try:
+                    preview = chunk_str[:200]
+                except Exception:
+                    preview = '<unavailable>'
+                self.ap.logger.warning(f"Failed to process chunk: {e}; chunk preview: {preview}")
+
+        # 流结束后，尝试解析残余 buffer
+        if buffer:
+            try:
+                buffer = buffer.strip()
+                if buffer:
+                    obj, _ = decoder.raw_decode(buffer)
+                    if isinstance(obj, dict):
+                        if obj.get('type') == 'item' and 'content' in obj:
+                            full_content += obj['content']
+                        elif obj.get('type') == 'end':
+                            is_final = True
                     message_idx += 1
                     yield provider_message.MessageChunk(
                         role='assistant',
@@ -95,8 +149,9 @@ class N8nServiceAPIRunner(runner.RequestRunner):
                         is_final=is_final,
                         msg_sequence=message_idx,
                     )
-            except json.JSONDecodeError:
-                self.ap.logger.warning(f"Failed to parse final JSON line: {response.text()}")
+            except Exception as e:
+                preview = buffer[:200]
+                self.ap.logger.warning(f"Failed to parse remaining buffer: {e}; buffer preview: {preview}")
 
     async def _call_webhook(self, query: pipeline_query.Query) -> typing.AsyncGenerator[provider_message.Message, None]:
         """调用n8n webhook"""