TICK script compute tag values over window

Hi there,
I think this is not possible but would like to know if there are any workaround.
I have a sensor network that streams sensor readings periodically every say 15 minutes, the sensors are not aligned e.g. same period but different offsets.

I want to calculate for every time window of 1 hour how many sensors are reporting doing the equivalent of a SHOW TAG VALUES ON in InfluxQL but for each time window. Then count the distinct values and then trigger an alert if there are less than the expected number.

I believe this is possible in Flux but I don't see a way to achieve it via a Tick Script.
Any suggestions are welcome.

Begin with TICKscript's windowing and tag-value capabilities; the issue names no file, test, or code entry point to inspect. Done would be a supported way to count distinct reporting sensors in each one-hour window and trigger the requested alert, or a clear documented limitation and workaround.

Written by the indexing model from the issue text.