progressive delivery

The loop is easy; the statistics are not. This question finds engineers who can size a traffic slice against sample noise and name the false rollback that kills trust in automation.

The interviewer does not want the three definitions. They want a decision, the number that justifies it, and what you do when the canary looks fine for nine minutes and then does not.

Deployment and release are two decisions, not one. The flag patterns that buy you instant reversibility, and the retirement discipline most teams skip.

Rings, SLI gates and Git-expressed promotion: sync waves order resources inside a cluster, but fleet sequencing is an automation you design on top.

For scheduled and stateful workloads the exposure unit is records and time, not requests: shadow runs on real input, row-level diff budgets, checkpoint compatibility, one-cycle warm standby.

The automation stopped because it could not decide, which is the correct behaviour and an incomplete design. Somebody has to decide, and the interesting question is what evidence that decision needs.