Stable Recurring Event ID

[Joe Allan Muharsky]

TL;DR: How do I get a stable recurring event ID for a "get next instance in series" query?

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Good morning,

I am trying to write an App Script that invites users to the "next" event in a recurring series.  I have used both the calendar API (via the Google Web UI and AppScript), and the Calendar UI (snowman) to find valid event ID's, and use Events.instances() to iterate through the available items.

The trouble I'm experiencing is that any given EventId (or RecurringEventId) doesn't seem to work for more than a week or two, and then I'm having to use the API and/or UI to hunt down "new" Event IDs to make the script work.

Is there a clear, canonical example of how to get the "next instance" in a recurring series, in a reliable/stable way?

Joe Allan