  ```yaml
  # Ruchy Compiler Refactoring Report
  # Critical Path to v1.0 Production Readiness
  # Generated: 2025-01-17

  project_health_assessment:
    critical_metrics:
      - parser_complexity: "1575 LoC in single file - architectural emergency"
      - transpiler_complexity: "897 LoC monolith - violates single responsibility"
      - test_coverage: "65% - unacceptable for compiler infrastructure"
      - technical_debt: "158 SATD markers - normalized corner-cutting"
      - defect_probability: "70% in CLI entry point - systemic quality issues"

    root_cause_analysis:
      primary_failure: "Feature velocity prioritized over foundational quality"
      secondary_failures:
        - "Insufficient modularization boundaries"
        - "Absent intermediate representation layer"
        - "Missing property-based invariant testing"
        - "Coupling between parsing and code generation"

  execution_phases:
    phase_1_fortification:
      freeze_directive: "NO NEW FEATURES until completion"
      duration: "2 weeks"
      success_criteria: "80% test coverage, zero SATD comments"

      tasks:
        test_coverage_improvement:
          priority: P0
          current: "65%"
          target: "85%"
          focus_areas:
            - transpiler_edge_cases: "Pattern exhaustiveness, type lowering"
            - parser_precedence: "Operator associativity, error recovery"
            - type_inference: "Polymorphic instantiation, constraint solving"
          implementation:
            - property_tests: "QuickCheck invariants for AST transformations"
            - mutation_testing: "Verify test effectiveness with cargo-mutants"
            - coverage_enforcement: "CI gate at 80% minimum"

        repl_technical_debt:
          priority: P0
          satd_count: 158
          actions:
            - replace_println_with_structured_errors: "Use thiserror crate"
            - implement_result_types: "No unwrap() in production paths"
            - add_integration_tests: "Full REPL session property tests"

        parser_modularization:
          priority: P0
          current_complexity: 1575
          target_per_module: "<300"
          decomposition:
            - expression_parser: "src/frontend/expr_parser.rs"
            - statement_parser: "src/frontend/stmt_parser.rs"
            - pattern_parser: "src/frontend/pattern_parser.rs"
            - precedence_climber: "src/frontend/precedence.rs"
            - error_recovery: "src/frontend/recovery.rs"

    phase_2_architectural_rebirth:
      duration: "3 weeks"
      success_criteria: "MIR pipeline operational, <5% performance regression"

      tasks:
        mir_implementation:
          priority: P0
          description: "Decouple frontend from backend via intermediate representation"

          core_types:
            location: "src/middleend/mir/mod.rs"
            structures:
              - BasicBlock: "Label, statements, terminator"
              - Statement: "Assignment, StorageLive, StorageDead"
              - Terminator: "Return, Jump, Switch, Call"
              - Rvalue: "Use, BinaryOp, UnaryOp, Aggregate"
              - Place: "Local variable or projection"

          lowering_pipeline:
            location: "src/middleend/lower.rs"
            phases:
              - name_resolution: "Resolve all identifiers to De Bruijn indices"
              - pattern_compilation: "Decision trees from match arms"
              - closure_conversion: "Lambda lifting with explicit captures"
              - control_flow_graph: "Linear code to basic blocks"

          optimization_passes:
            location: "src/middleend/optimize/"
            mandatory:
              - dead_code_elimination: "Mark-and-sweep on CFG"
              - constant_propagation: "SCCP algorithm"
              - common_subexpression: "Value numbering"
            optional:
              - inline_expansion: "Cost model based on IR size"
              - loop_invariant_motion: "LICM with alias analysis"

          backend_trait:
            location: "src/backend/codegen.rs"
            interface: |
              trait CodeGenerator {
                type Output;
                fn generate(&mut self, mir: &Mir) -> Result<Self::Output>;
              }
            implementations:
              - RustBackend: "MIR -> syn::File"
              - CraneliftBackend: "MIR -> cranelift_codegen::ir::Function"
              - InterpreterBackend: "MIR -> runtime::Value"

    phase_3_controlled_innovation:
      duration: "4 weeks"
      success_criteria: "Feature parity with specification"

      tasks:
        actor_system:
          priority: P0
          architecture: "Erlang OTP principles with Rust ownership"

          supervision_tree:
            location: "src/runtime/actors/supervisor.rs"
            strategies:
              - one_for_one: "Restart failed child only"
              - one_for_all: "Restart all children on any failure"
              - rest_for_one: "Restart failed child and younger siblings"
            implementation:
              - "Arc<Mutex<SupervisorState>> for shared state"
              - "tokio::select! for concurrent child monitoring"
              - "Exponential backoff with jitter for restarts"

          message_passing:
            location: "src/runtime/actors/mailbox.rs"
            design:
              - bounded_mpsc: "tokio::sync::mpsc with backpressure"
              - selective_receive: "Pattern guards on message queue"
              - priority_queue: "Binary heap for message ordering"

          lifecycle_hooks:
            - pre_start: "Resource acquisition"
            - post_stop: "Cleanup handlers"
            - pre_restart: "State preservation"

        mcp_integration:
          priority: P0
          description: "Compiler-aware Model Context Protocol"

          type_system_integration:
            location: "src/middleend/mcp_types.rs"
            features:
              - tool_signatures: "Function types map to MCP tools"
              - context_types: "Conversation state as refinement types"
              - capability_types: "Static verification of protocol adherence"

          code_generation:
            location: "src/backend/mcp_codegen.rs"
            outputs:
              - client_stubs: "Async trait implementations"
              - server_scaffolding: "Handler registration boilerplate"
              - transport_adapters: "stdio/WebSocket/pipe abstractions"

  quality_gates:
    phase_transitions:
      phase_1_to_2:
        - "Test coverage >= 80%"
        - "Zero SATD comments"
        - "Parser complexity < 300 per module"

      phase_2_to_3:
        - "MIR pipeline passes all tests"
        - "Performance regression < 5%"
        - "Clean architecture validation via cargo-deny"

      release_1_0:
        - "Test coverage >= 85%"
        - "Zero known defects > P2"
        - "Benchmark parity with handwritten Rust"
        - "Property tests for all invariants"

  risk_mitigation:
    complexity_creep:
      monitoring: "Weekly complexity metrics via rust-code-analysis"
      threshold: "Alert if any module > 300 LoC complexity"
      action: "Immediate refactoring sprint"

    performance_regression:
      monitoring: "Continuous benchmarking via criterion"
      threshold: "5% degradation blocks merge"
      action: "Profile with perf, optimize hot paths"

    test_quality:
      monitoring: "Mutation testing coverage"
      threshold: "80% mutant kill rate"
      action: "Strengthen test assertions"

  success_metrics:
    technical:
      - startup_time: "< 10ms"
      - repl_latency: "< 15ms"
      - transpilation_overhead: "< 5% vs handwritten"
      - binary_size: "< 5MB minimal runtime"

    quality:
      - test_coverage: "> 85%"
      - cyclomatic_complexity: "< 10 per function"
      - cognitive_complexity: "< 15 per function"
      - defect_density: "< 0.1 per KLOC"

  conclusion:
    status: "Project at critical inflection point"
    prescription: "Disciplined execution of three-phase plan"
    timeline: "9 weeks to stable v1.0 foundation"
    outcome: "Transform from fragile prototype to industrial-strength compiler"
    ```