While reading this I was thinking about how it would integrate with the OS calendar implementations, I my primary thought was to have it connect use the description field as a text document with all the additional metadata about each event. Possibly as YAML, JSON, or some custom human readable format
I've had similar ideas and have tried little scripts that do this. It's a start but I think the crucial issue is the format and ui of calendar apps. It doesn't feel durable or easily searchable. And they've been seemingly stagnant for years.
