Don't switch in one step
A new prompt or model goes live the way other production code does: behind a feature flag, canaried at low traffic, monitored, then ramped up. Atomic switches are how regressions ship.
Rollout pattern
- Internal canary — your team and select power users.
- Canary traffic — 1–5% of production. Watch the dashboards.
- Ramp — 10% → 25% → 50% → 100% over hours or days, depending on stakes.
- Hold — at 100%, leave the previous version reachable for instant rollback.
- Cleanup — once stable for ≥1 week, retire the previous version.
What you watch during ramp
- Quality dashboards (eval flags, complaint rate).
- Cost spikes per call.
- Latency p95.
- Refusal rate.
- Specific failure modes you flagged in pre-ship review.