Classic blue-green gives you instant rollback, but it doesn’t tell you how the new version behaves under real production traffic. In this session I’ll show a “mirror-first” pattern with Octopus and Istio: run the new version next to the live one, copy real requests to it, watch logs/latency/auth, and only promote to the live color if it stays clean. You get safer rollouts, better signals, and you keep the simple blue → green (or back) switch.