Files
AI-Trader/agent/chat_model_wrapper.py
Bill 5c73f30583 fix: patch parse_tool_call bug that returns string args instead of dict
Root cause identified: langchain_core's parse_tool_call() sometimes returns
tool_calls with 'args' as a JSON string instead of parsed dict object.

This violates AIMessage's Pydantic schema which expects args to be dict.

Solution: Wrapper now detects when parse_tool_call returns string args
and immediately converts them to dict using json.loads().

This is a workaround for what appears to be a LangChain bug where
parse_tool_call's json.loads() call either:
1. Fails silently without raising exception, or
2. Succeeds but result is not being assigned to args field

The fix ensures AIMessage always receives properly parsed dict args,
resolving Pydantic validation errors for all DeepSeek tool calls.
2025-11-06 17:58:41 -05:00

184 lines
9.6 KiB
Python

"""
Chat model wrapper to fix tool_calls args parsing issues.
DeepSeek and other providers return tool_calls.args as JSON strings, which need
to be parsed to dicts before AIMessage construction.
"""
import json
from typing import Any, Optional, Dict
from functools import wraps
class ToolCallArgsParsingWrapper:
"""
Wrapper that adds diagnostic logging and fixes tool_calls args if needed.
"""
def __init__(self, model: Any, **kwargs):
"""
Initialize wrapper around a chat model.
Args:
model: The chat model to wrap
**kwargs: Additional parameters (ignored, for compatibility)
"""
self.wrapped_model = model
self._patch_model()
def _patch_model(self):
"""Monkey-patch the model's _create_chat_result to add diagnostics"""
if not hasattr(self.wrapped_model, '_create_chat_result'):
# Model doesn't have this method (e.g., MockChatModel), skip patching
return
# CRITICAL: Patch parse_tool_call in base.py's namespace (not in openai_tools module!)
from langchain_openai.chat_models import base as langchain_base
original_parse_tool_call = langchain_base.parse_tool_call
def patched_parse_tool_call(raw_tool_call, *, partial=False, strict=False, return_id=True):
"""Patched parse_tool_call to fix string args bug and add logging"""
result = original_parse_tool_call(raw_tool_call, partial=partial, strict=strict, return_id=return_id)
if result:
args_type = type(result.get('args', None)).__name__
print(f"[DIAGNOSTIC] parse_tool_call returned: args type = {args_type}")
if args_type == 'str':
print(f"[DIAGNOSTIC] ⚠️ BUG FOUND! parse_tool_call returned STRING args, fixing...")
# FIX: parse_tool_call sometimes returns string args instead of dict
# This happens when it fails to parse but doesn't raise an exception
try:
result['args'] = json.loads(result['args'])
print(f"[DIAGNOSTIC] ✓ Fixed! Converted string args to dict")
except (json.JSONDecodeError, TypeError) as e:
print(f"[DIAGNOSTIC] ❌ Failed to parse args: {e}")
# Leave as string if we can't parse it
return result
# Replace in base.py's namespace (where _convert_dict_to_message uses it)
langchain_base.parse_tool_call = patched_parse_tool_call
original_create_chat_result = self.wrapped_model._create_chat_result
@wraps(original_create_chat_result)
def patched_create_chat_result(response: Any, generation_info: Optional[Dict] = None):
"""Patched version with diagnostic logging and args parsing"""
import traceback
response_dict = response if isinstance(response, dict) else response.model_dump()
# DIAGNOSTIC: Log response structure for debugging
print(f"\n[DIAGNOSTIC] _create_chat_result called")
print(f" Response type: {type(response)}")
print(f" Call stack:")
for line in traceback.format_stack()[-5:-1]: # Show last 4 stack frames
print(f" {line.strip()}")
print(f"\n[DIAGNOSTIC] Response structure:")
print(f" Response keys: {list(response_dict.keys())}")
if 'choices' in response_dict and response_dict['choices']:
choice = response_dict['choices'][0]
print(f" Choice keys: {list(choice.keys())}")
if 'message' in choice:
message = choice['message']
print(f" Message keys: {list(message.keys())}")
# Check for raw tool_calls in message (before parse_tool_call processing)
if 'tool_calls' in message:
tool_calls_value = message['tool_calls']
print(f" message['tool_calls'] type: {type(tool_calls_value)}")
if tool_calls_value:
print(f" tool_calls count: {len(tool_calls_value)}")
for i, tc in enumerate(tool_calls_value): # Show ALL
print(f" tool_calls[{i}] type: {type(tc)}")
print(f" tool_calls[{i}] keys: {list(tc.keys()) if isinstance(tc, dict) else 'N/A'}")
if isinstance(tc, dict):
if 'function' in tc:
print(f" function keys: {list(tc['function'].keys())}")
if 'arguments' in tc['function']:
args = tc['function']['arguments']
print(f" function.arguments type: {type(args).__name__}")
print(f" function.arguments value: {str(args)[:100]}")
if 'args' in tc:
print(f" ALSO HAS 'args' KEY: type={type(tc['args']).__name__}")
print(f" args value: {str(tc['args'])[:100]}")
# Fix tool_calls: Normalize to OpenAI format if needed
if 'choices' in response_dict:
for choice in response_dict['choices']:
if 'message' not in choice:
continue
message = choice['message']
# Fix tool_calls: Ensure standard OpenAI format
if 'tool_calls' in message and message['tool_calls']:
print(f"[DIAGNOSTIC] Processing {len(message['tool_calls'])} tool_calls...")
for idx, tool_call in enumerate(message['tool_calls']):
# Check if this is non-standard format (has 'args' directly)
if 'args' in tool_call and 'function' not in tool_call:
print(f"[DIAGNOSTIC] tool_calls[{idx}] has non-standard format (direct args)")
# Convert to standard OpenAI format
args = tool_call['args']
tool_call['function'] = {
'name': tool_call.get('name', ''),
'arguments': args if isinstance(args, str) else json.dumps(args)
}
# Remove non-standard fields
if 'name' in tool_call:
del tool_call['name']
if 'args' in tool_call:
del tool_call['args']
print(f"[DIAGNOSTIC] Converted tool_calls[{idx}] to standard OpenAI format")
# Fix invalid_tool_calls: dict args -> string
if 'invalid_tool_calls' in message and message['invalid_tool_calls']:
print(f"[DIAGNOSTIC] Checking invalid_tool_calls for dict-to-string conversion...")
for idx, invalid_call in enumerate(message['invalid_tool_calls']):
if 'args' in invalid_call:
args = invalid_call['args']
# Convert dict arguments to JSON string
if isinstance(args, dict):
try:
invalid_call['args'] = json.dumps(args)
print(f"[DIAGNOSTIC] Converted invalid_tool_calls[{idx}].args from dict to string")
except (TypeError, ValueError) as e:
print(f"[DIAGNOSTIC] Failed to serialize invalid_tool_calls[{idx}].args: {e}")
# Keep as-is if serialization fails
# Call original method with fixed response
print(f"[DIAGNOSTIC] Calling original_create_chat_result...")
result = original_create_chat_result(response_dict, generation_info)
print(f"[DIAGNOSTIC] original_create_chat_result returned successfully")
print(f"[DIAGNOSTIC] Result type: {type(result)}")
if hasattr(result, 'generations') and result.generations:
gen = result.generations[0]
if hasattr(gen, 'message') and hasattr(gen.message, 'tool_calls'):
print(f"[DIAGNOSTIC] Result has {len(gen.message.tool_calls)} tool_calls")
if gen.message.tool_calls:
tc = gen.message.tool_calls[0]
print(f"[DIAGNOSTIC] tool_calls[0]['args'] type in result: {type(tc['args'])}")
return result
# Replace the method
self.wrapped_model._create_chat_result = patched_create_chat_result
@property
def _llm_type(self) -> str:
"""Return identifier for this LLM type"""
if hasattr(self.wrapped_model, '_llm_type'):
return f"wrapped-{self.wrapped_model._llm_type}"
return "wrapped-chat-model"
def __getattr__(self, name: str):
"""Proxy all attributes/methods to the wrapped model"""
return getattr(self.wrapped_model, name)
def bind_tools(self, tools: Any, **kwargs):
"""Bind tools to the wrapped model"""
return self.wrapped_model.bind_tools(tools, **kwargs)
def bind(self, **kwargs):
"""Bind settings to the wrapped model"""
return self.wrapped_model.bind(**kwargs)