Retention cohorts group your contacts by the week they signed up, then track how many of each week’s cohort are still engaging in the weeks that follow. It’s the classic triangle chart for spotting whether newer cohorts stick around better or worse than older ones.
Endpoint
Session-authenticated, org-scoped. Any role.
Query parameters
How many weeks of the retention curve to compute per cohort. Clamped to 1–26.
Response
Cohorts are derived from each contact’s signup week (created_at) versus its last engagement (last_engaged_at).
Powers
The Retention cohort triangle on the analytics dashboard, each row a signup week, each column a week-offset retention percentage. 
