The "Repeat Task" feature and RRULE

[ReduxST]

I was exploring the task repeat feature with the goal of improving it, #4195 in particular right now. While thinking about how to best implement this, it occurred to me that using the iCalendar Recurrence Rule standard (RRULE) would provide a more elegant solution for implementing it and probably many other features.

Adopting RRULE, which is the standard used in nearly all modern calendar applications, could solve the single-instance deletion issue cleanly. It might also make the entire "repeat task" feature more powerful and customizable. Future additions could become easier to implement, and we could potentially even allow users to write their own rules directly via an "advanced" option.

While researching, I found that the original rrule.js library is no longer actively maintained. However, a new library, rrule-temporal, was created to succeed it. It's built on the modern Temporal API and seems pretty solid.

I'm sure there may have been good reasons RRULE wasn't used initially, so I wanted to start a discussion to understand the history and potential challenges. The main challenge I foresee would be creating a migration path to convert existing repeat configurations to the RRULE format for users updating the app.

What are your thoughts on this? Are there any major roadblocks or concerns I might be missing?

[johannesjo]

Thanks for your suggestion! I certainly will have a look once I tackle the issue!