I know you can use GET /tags/tag-id/tasks
and get all the tasks for a given tag
then I could do it again with a different tag-id and get the intersection of the two lists...
but is there anyway to get all the tasks with both the tags in a single query?
or would I have to group the tags into a single tag, something like the example below
tags = ["Software","Web"] ===> tag = "Software-Web"
You are correct in your assumptions. There is no way to get the intersection or the union of multiple tags in one call
Currently you can only query tasks using one tag per call. I will add this to the list of requested features.
For now you can follow API changes at https://www.apichangelog.com/api/asana and we are hoping to have a public API roadmap on our docs soon.