Choosing a Rollout Strategy and Rollback Triggers

All 40 prompts pass their golden sets on the rewritten, new-model version. You need to move from "passes offline evals" to "fully serving production traffic" for a high-criticality prompt in the checkout path.

1. Compare shadow, canary, and interleaved A/B rollout: what each one catches that offline evals cannot, and what each costs.
2. Design the rollout sequence for this specific prompt, in order, and justify why you would not skip a stage.
3. Give three concrete, automatable rollback triggers — not "roll back if it looks bad."