Module runner 

Core pipeline execution engine.

Implements the lifecycle: PARSE → VALIDATE → INITIALIZE → EXECUTE → FINALIZE. The core loop follows the spec Section 3.2 exactly:

1. Execute node handler → get Outcome
2. Apply context_updates from Outcome
3. Save checkpoint
4. Select next edge (5-step algorithm)
5. At terminal nodes: check goal gates → retry_target if unsatisfied
6. Retry logic with exponential backoff + jitter

Structs

PipelineRunner

The pipeline execution engine.