Add CrossPlanCorrectionService that implements the four child-plan-state-
dependent behaviours from the specification when a correction's affected
subtree includes child plans:
- Not yet started → cancel the child plan
- In progress → cancel + rollback sandbox to pre-child-plan state
- Completed but not applied → cancel + rollback sandbox
- Already applied → reject the correction (CorrectionRejection)
Key additions:
- ChildPlanState enum classifying child plans into 4 states
- CorrectionRejection result type with reason and affected applied plan IDs
- CascadeAction/CascadeResult models for cascade operation tracking
- CorrectionStatus.REJECTED for rejected corrections
- Atomic cascade-or-rollback: all child plan actions succeed or the
entire cascade is rolled back
- Protocol-based dependency injection (ChildPlanLookup, ChildPlanCanceller,
SandboxRollbacker) for testability
- execute_correction_with_cascade() integrates with CorrectionService flow
Testing:
- 24 Behave BDD scenarios in cross_plan_correction.feature
- 8 Robot Framework end-to-end smoke tests
- ASV benchmarks for cascade performance with varying child plan counts
ISSUES CLOSED: #547
