Calendar Filter
Subscribe to the calendars you are given; publish the calendar you actually want.
Calendar Filter sits between a calendar you subscribe to and the app you read it in. It fetches the feeds you point it at, drops the events you do not care about, fixes titles, locations and times that come through wrong, merges several sources into one, and publishes the result as a new feed. Your calendar app subscribes to that.
Two calendars in, filtered and tidied, merged by priority, one clean feed out.
Everything is a rule you wrote, so a feed gives the same answer every time it is fetched — nothing is guessed, and nothing changes behind your back.
Please contact dev@delichon.no if you want to try it out.