What Must the Off-Policy Gate Show Before Launch?

You have a candidate surge policy trained on two weeks of logs from the incumbent rule with 20 percent uniform exploration. Offline, its estimated value is higher than the rule's. A colleague says "ship it to the switchback".

1. List what the logs must contain for off-policy evaluation to be possible at all.
2. List what the gate must show, beyond a higher point estimate.
3. Explain what the gate cannot tell you, and what you do about that.