End date of this segment (exclusive).
Total count of events (for display when collapsed).
Events within this time segment.
Current expansion state of the segment.
Human-readable label for the segment.
"December 2025", "Week of Nov 25", "Q4 2025"
Start date of this segment (inclusive).
Represents a collapsible time segment (e.g., "December 2025"). Contains a collection of events within the time period.