feat: enhance request payload handling for DeepSeek API compatibility

Author: liuruibin

apps/models_provider/impl/base_chat_open_ai.py

@@ -1,13 +1,14 @@
 # coding=utf-8
 import base64
+import json
 from concurrent.futures import ThreadPoolExecutor
 from requests.exceptions import ConnectTimeout, ReadTimeout
 from typing import Dict, Optional, Any, Iterator, cast, Union, Sequence, Callable, Mapping
 
 from langchain_core.language_models import LanguageModelInput
 from langchain_core.messages import BaseMessage, get_buffer_string, BaseMessageChunk, HumanMessageChunk, AIMessageChunk, \
     SystemMessageChunk, FunctionMessageChunk, ChatMessageChunk
-from langchain_core.messages.ai import UsageMetadata
+from langchain_core.messages.ai import UsageMetadata, AIMessage
 from langchain_core.messages.tool import tool_call_chunk, ToolMessageChunk
 from langchain_core.outputs import ChatGenerationChunk
 from langchain_core.runnables import RunnableConfig, ensure_config
@@ -218,6 +219,57 @@ def invoke(
             'token_usage'] if 'token_usage' in chat_result.response_metadata else chat_result.usage_metadata
         return chat_result
 
+    def _get_request_payload(
+            self,
+            input_: LanguageModelInput,
+            *,
+            stop: list[str] | None = None,
+            **kwargs: Any,
+    ) -> dict:
+        # Get original messages to preserve reasoning_content before base conversion
+        messages = self._convert_input(input_).to_messages()
+        # Store reasoning_content for AIMessages with tool_calls
+        # According to DeepSeek API docs, reasoning_content is REQUIRED when tool_calls
+        # are present during the tool invocation process (within same question/turn).
+        # See: https://api-docs.deepseek.com/guides/thinking_mode#tool-calls
+        reasoning_content_map = {}
+        for i, msg in enumerate(messages):
+            if (
+                    isinstance(msg, AIMessage)
+                    and (msg.tool_calls or msg.invalid_tool_calls)
+                    and (reasoning := msg.additional_kwargs.get("reasoning_content"))
+            ):
+                reasoning_content_map[i] = reasoning
+
+        payload = super()._get_request_payload(input_, stop=stop, **kwargs)
+
+        # Restore reasoning_content for assistant messages with tool_calls
+        # This is required by DeepSeek API - missing it causes 400 error
+        if "messages" in payload and reasoning_content_map:
+            for i, message in enumerate(payload["messages"]):
+                if (
+                        i in reasoning_content_map
+                        and message.get("role") == "assistant"
+                        and message.get("tool_calls")
+                ):
+                    message["reasoning_content"] = reasoning_content_map[i]
+
+        # Apply DeepSeek-specific message formatting
+        for message in payload["messages"]:
+            if message["role"] == "tool" and isinstance(message["content"], list):
+                message["content"] = json.dumps(message["content"])
+            elif message["role"] == "assistant" and isinstance(
+                    message["content"], list
+            ):
+                # DeepSeek API expects assistant content to be a string, not a list.
+                # Extract text blocks and join them, or use empty string if none exist.
+                text_parts = [
+                    block.get("text", "")
+                    for block in message["content"]
+                    if isinstance(block, dict) and block.get("type") == "text"
+                ]
+                message["content"] = "".join(text_parts) if text_parts else ""
+        return payload
 
     def upload_file_and_get_url(self, file_stream, file_name):
         """上传文件并获取文件URL"""