"""Service layer for business logic (ADR-006).

Services are framework-agnostic and handle:
- Data aggregation and transformation
- Cache management
- Business rule validation
- Exception handling

Services do NOT handle:
- MCP protocol formatting
- HTTP transport concerns
- User-facing error messages

This separation enables:
- Testing without MCP framework
- Future reuse in REST API, CLI, webhooks
- Clear boundaries between transport and logic
"""
