Project engagement rollup

Sends, delivery, opens, clicks, bounces and unsubscribes for the whole project over a window, with the previous window alongside for comparison and a gap-free daily series for charting.

Test and live are separate populations, and which one you get is decided by the key you authenticate with rather than by a parameter — a sk_test_… key can never report production figures. This matters more than it sounds: in a project that has been integrated against, more than half the rows in the send log can be test sends, and totalling GET /v1/emails without filtering them produces a delivery rate that is wrong by tens of points.

Rates compare in points, sends compare in percent. An open rate moving 35% → 38% is reported as openPoints: 3, because "open rate up 8%" is ambiguous and "up 3 points" is not. sentPercent is a true percentage change, and is null rather than 0 when the previous window had no sends at all — those are different facts.

delivered counts every message that reached the mailbox, so it includes the ones that went on to be opened and clicked. Statuses only move forward, so each stage necessarily contains the ones past it.