I really like your unbounded retention feature, I was waiting for this for years! Great to see it has been build.
I have one problem with it though. We are a travel app with an annual summer peak. For us to do proper analysis, we need to group our cohorts by year and then look at the year-on-year retention. However in Mixpanel it's only possible to group by day/week/month.
Would it be possible for you to add a "quarter" and "year" option here? Without it I can't do any analysis that makes sense, because the monthly cohorts are too much affected by seasonality. Also for non-travel apps I guess it would make sense to be able to see year-on-year retention rather than the cluttered month view below.