# Semantic Scholar Server Refactoring

This document describes the refactoring of the Semantic Scholar server from a single monolithic file to a modular package structure.

## Motivation

The original implementation consisted of a single 2,200+ line Python file (`semantic_scholar_server.py`), which made it difficult to:

- Understand the overall structure
- Locate specific functionality
- Debug issues
- Make focused changes
- Test individual components

## Refactoring Approach

We used a modular package approach, separating concerns into logical components:

```
semantic-scholar-server/
├── semantic_scholar/            # Main package
│   ├── __init__.py             # Package initialization
│   ├── server.py               # Server setup and main functionality
│   ├── mcp.py                  # Centralized FastMCP instance definition
│   ├── config.py               # Configuration classes
│   ├── utils/                  # Utility modules
│   │   ├── __init__.py
│   │   ├── errors.py           # Error handling
│   │   └── http.py             # HTTP client and rate limiting
│   ├── api/                    # API endpoints
│       ├── __init__.py
│       ├── papers.py           # Paper-related endpoints
│       ├── authors.py          # Author-related endpoints
│       └── recommendations.py  # Recommendation endpoints
├── run.py                      # Entry point script
```

## Key Improvements

1. **Separation of Concerns**

   - Config classes in their own module
   - Utilities separated from business logic
   - API endpoints grouped by domain (papers, authors, recommendations)
   - Server infrastructure code isolated
   - FastMCP instance centralized in its own module

2. **Improved Maintainability**

   - Each file has a single responsibility
   - Files are much smaller and easier to understand
   - Clear imports show dependencies between modules
   - Better docstrings and code organization
   - No circular dependencies between modules

3. **Enhanced Extensibility**

   - Adding new endpoints only requires changes to the relevant module
   - Utilities can be reused across the codebase
   - Configuration is centralized
   - Testing individual components is much easier
   - Each module imports the FastMCP instance from a central location

4. **Clearer Entry Point**
   - `run.py` provides a simple way to start the server
   - Server initialization is separated from the API logic
   - All modules consistently import the FastMCP instance from mcp.py

## Migration Guide

The refactored code maintains the same functionality and API as the original implementation. To migrate:

1. Replace the original `semantic_scholar_server.py` with the new package structure
2. Update any import statements that referenced the original file
3. Use `run.py` as the new entry point

No changes to API usage are required - all tool functions maintain the same signatures and behavior.

## Future Improvements

The modular structure enables several future improvements:

1. **Testing**: Add unit tests for individual components
2. **Caching**: Implement caching layer for improved performance
3. **Logging**: Enhanced logging throughout the application
4. **Metrics**: Add performance monitoring
5. **Documentation**: Generate API documentation from docstrings
