The lists carry two occurrences because they answer "what ends soonest";
the board exists to show rhythm, so it draws every occurrence in view.
expand is called with the settled window rather than returning rows up
front, and the ordering is the point: boardWindow takes its max from the
ends it is handed, so feeding expanded occurrences back into it would widen
the window, generate more, and widen it again — a rule with no until would
never terminate. Compute the range from the base rows, then expand into it.
Merged rows are re-sorted only when there is something to merge, so a
reader with no repeating events sees identical behaviour.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
