IMPORT_FIXES.md

Langchain 0.3.27 Import Fixes - Complete Reference

Last Updated: After multiple iterations of import corrections
Status: ✅ All critical imports validated for langchain 0.3.27

Problem Summary

The web3-research-agent uses LangChain. Version 0.3.27 underwent major restructuring where:

1. Memory classes were moved to langchain_classic namespace
2. Tool base classes are in langchain_core.tools
3. LLM integrations remained in their respective packages

Final Correct Imports (VERIFIED)

1. Memory Imports ✅

# CORRECT (langchain_classic.memory):
from langchain_classic.memory import ConversationBufferWindowMemory

# WRONG (these don't exist in 0.3.27):
# ❌ from langchain.memory import ConversationBufferWindowMemory
# ❌ from langchain_community.memory import ConversationBufferWindowMemory

Files Fixed:

• src/agent/memory_manager.py (line 1)
• src/agent/research_agent.py (line 3)

2. Tool Base Class ✅

# CORRECT (langchain_core.tools):
from langchain_core.tools import BaseTool

# WRONG:
# ❌ from langchain_community.tools import BaseTool
# ❌ from langchain.tools import BaseTool

Files Using This:

• src/tools/base_tool.py (line 3)
• src/tools/chart_data_tool.py (line 1)
• src/tools/chart_creator_tool.py (line 1)

3. LLM Integrations ✅ (Also Correct)

# Google Generative AI (Gemini):
from langchain_google_genai import ChatGoogleGenerativeAI

# Ollama (Local):
from langchain_community.llms import Ollama

4. Pydantic Models ✅

# All are correct Pydantic v2:
from pydantic import BaseModel, Field, PrivateAttr, field_validator

All Langchain Imports in Codebase

File	Import	Status
src/agent/memory_manager.py	from langchain_classic.memory import ConversationBufferWindowMemory	✅
src/agent/research_agent.py (L1)	from langchain_google_genai import ChatGoogleGenerativeAI	✅
src/agent/research_agent.py (L2)	from langchain_community.llms import Ollama	✅
src/agent/research_agent.py (L3)	from langchain_classic.memory import ConversationBufferWindowMemory	✅
src/tools/base_tool.py	from langchain_core.tools import BaseTool	✅
src/tools/chart_data_tool.py	from langchain_core.tools import BaseTool	✅
src/tools/chart_creator_tool.py	from langchain_core.tools import BaseTool	✅
debug_gemini.py	from langchain_google_genai import ChatGoogleGenerativeAI	✅

Requirements.txt Dependencies

All packages confirmed in requirements.txt:

langchain                    # Main package (includes langchain_classic)
langchain-google-genai      # Google Generative AI (Gemini)
langchain-community         # Community integrations (Ollama, etc.)
google-generativeai         # Google AI API
pydantic                    # Data validation
... (other dependencies)

Why Langchain_classic?

In langchain 0.3.27:

• Memory classes moved to langchain_classic (backwards compatibility layer)
• These are marked @deprecated(since="0.3.1", removal="1.0.0")
• langchain_classic serves as a compatibility bridge
• Full migration would require replacing with RunnableWithMessageHistory (future work)

Prevention Checklist

✅ No imports from non-existent modules
✅ All BaseTool imports from langchain_core.tools
✅ All memory imports from langchain_classic.memory
✅ All LLM integrations from correct packages
✅ No circular imports detected
✅ Pydantic v2 syntax used consistently

Next Error Discovery Method

If new import errors occur:

1. Check error message for module path
2. Verify in langchain GitHub - libs/langchain/ folder
3. Look for __init__.py exports to find actual location
4. Never assume module is available under base langchain package - check langchain_classic or langchain_core

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Last Fix Commit: ac70217 - Fixed memory imports to use langchain_classic