Simplify model conversions with factory pattern

[jonpspri]

Problem

Complex conversions between internal models and Pydantic models (e.g., AutoSaveConfig) are currently handled through ad-hoc conversion methods scattered across the codebase. This creates maintainability issues and potential inconsistencies.

Proposed Solution

Implement a factory pattern to standardize and simplify conversions between:

• Internal data models and Pydantic models
• TypedDict structures and Pydantic models
• Configuration objects and their various representations

Benefits

• Consistency: Centralized conversion logic reduces code duplication
• Maintainability: Single location for conversion rules makes updates easier
• Type Safety: Factory pattern can ensure proper type validation during conversions
• Extensibility: Easy to add new model types and conversion rules

Implementation Ideas

1. Create a ModelFactory class with methods like:

   • from_dict() - Convert dict/TypedDict to Pydantic model
   • to_dict() - Convert Pydantic model to dict
   • convert() - Convert between different model types

2. Use generic typing to maintain type safety

3. Consider using protocols/interfaces for consistent conversion behavior

Examples of Current Complex Conversions

• AutoSaveConfig conversions in session management
• FilterCondition/FilterConditionDict handling in transformation server
• Result model conversions across server boundaries

Acceptance Criteria

• Design factory pattern interface
• Implement factory for AutoSaveConfig conversions
• Migrate existing ad-hoc conversions to use factory
• Add comprehensive tests for factory pattern
• Update documentation with conversion guidelines

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Originally identified in PR review for type safety improvements and test coverage enhancements.