PARTIAL: Phase 2 infrastructure complete, full migration requires substantial additional work

COMPLETED:
- Error propagation preprocessor (pkg/preprocessor/error_prop.go) - WORKING
- Preprocessor framework tests
- Basic transformation logic for simple cases

CHALLENGES IDENTIFIED:
1. The existing codebase uses old plugin-based architecture throughout
2. CLI, tests, and all integration points need complete rewiring
3. Each feature (lambdas, sum types, pattern matching, etc.) needs both preprocessor AND transformer
4. Scope is 6-8 full development sessions (~16-24 hours) as estimated in plan
5. Cannot complete entire migration in single session

REALISTIC PATH FORWARD:
- Current session achieved: Phase 2.1 (error prop preprocessor working)
- Remaining: Phases 2.2-7 (transformer, lambdas, sum types, patterns, operators, integration)
- Recommendation: Continue incrementally over multiple sessions as originally planned
