Time Utilities

The Time Utilities module (lib/time.ts) provides standardized date and time helper functions used across the application.

Core Functions

Function	Purpose
formatTimeRange(start, end)	Formats an epoch range into “6:00 AM - 8:00 AM” display string
toLocalEpoch(date)	Converts a Date object to epoch milliseconds in the local timezone
fromEpoch(ms)	Converts epoch milliseconds to a dayjs object
isToday(epoch)	Checks if an epoch timestamp falls on the current calendar day
getRelativeDay(epoch)	Returns “Today”, “Tomorrow”, or the formatted date string

Timezone Safety

All time operations use dayjs with timezone awareness. Epoch timestamps stored in SQLite and Convex are always in UTC. Display formatting always converts to the device’s local timezone.