Phase 5 of Context Management Engine - Model Adapters:
- Add ModelAdapter abstract base class with model matching
- Add DefaultAdapter for unknown models (plain text)
- Add ClaudeAdapter with XML-based formatting:
- <system_instructions> for system context
- <reference_documents>/<document> for knowledge
- <conversation_history>/<message> for chat
- <tool_results>/<tool_result> for tool outputs
- XML escaping for special characters
- Add OpenAIAdapter with markdown formatting:
- ## headers for sections
- ### Source headers for documents
- **ROLE** bold labels for conversation
- Code blocks for tool outputs
- Add get_adapter() factory function for model selection
Tests: 33 new tests, 256 total context tests passing
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
