Verify one model's hand-off artifact with a different model family before downstream agents execute it — same-model authoring, cross-model verification — catching gaps and contradictions that same-family review shares blind spots with. Use this when rework loops trace back to incomplete hand-offs (execution prompts, blueprints, specs), when self-review keeps grading its own work too kindly, when you want a second opinion that can never block the pipeline while it's being evaluated, or when wiring an external verifier that must fail soft.
