# Pydantic V2 Migration Fixes

## Summary
This PR completes the Pydantic V2 migration by fixing the remaining issues discovered during comprehensive testing and resolves all mypy type errors.

## Issues Fixed

### 1. Missing Type Annotations for Private Attributes
- Added type annotations to private attributes in `XMLToolMessage`, `ArangoDBTool`, and test files
- Example: `_allow_llm_use: bool = True`

### 2. DoneTool Content Field Type Strictness
- Added field validator to handle Pydantic V2's stricter type validation
- Automatically converts any input type to string for backward compatibility

### 3. GlobalState Singleton Pattern
- Fixed ModelPrivateAttr handling when accessing class-level private attributes
- Added proper type checking for PydanticUndefined values

### 4. ParsingConfig chunk_size Float Coercion
- Added field validators to maintain backward compatibility with float inputs
- Applied to both ParsingConfig and MarkdownChunkConfig

### 5. Crawl4aiConfig Forward Reference Resolution
- Replaced deprecated `update_forward_refs()` with `model_rebuild()`
- Moved resolution to module level after class definition

### 6. Mypy Type Errors
- Fixed return type annotations in field validators
- Added explicit exports to `langroid.pydantic_v1.__init__.py`
- Corrected type handling in various modules

## Testing
- Tested all 83 test files in tests/main/
- Tested all 11 test files in tests/extras/ (with dependencies)
- All Pydantic V2 related issues resolved
- No regressions introduced

## Documentation
- Created comprehensive migration log documenting all findings
- Organized documentation under `issues/pydantic-v2-migration/`