Work with Apple Calendar events synced to ~/Documents/alto-index/calendar/.
If $ARGUMENTS is a date, show events for that date. If a query, search events for that text.
If no arguments, show upcoming events:
- check today's and tomorrow's date folders across all calendars
- show event title, time, location, and attendees
- list which calendars are synced
Always include the calshow: deep link from the link frontmatter field.
If the calendar folder doesn't exist, tell the user to enable Calendar sync in alto.index.