1a1b5cc5ed
- StageCheckpointPassed/FailedEvent (registered + serialization test): per-stage reconciliation of produced artifacts vs the locked plan's produces-slots - StageCheckpointReconciler (pure) + tests - emitStageCheckpoint wired in after verifyProduces, runs regardless of its pass/fail (verifyProduces still owns the halt); gated on an ExecutionPlanLocked in the session log so non-plan workflows are unaffected Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>