Planning notes
A common reference
PLANNING NOTE 01
One instant can have several local dates ↗
Use UTC as the shared anchor, then read every local date.
PLANNING NOTE 02Make overnight windows belong to the right day ↗
A checked weekday identifies the day an overnight shift starts.
PLANNING NOTE 03Recheck the date, then carry the instant into a calendar ↗
Named zones and fixed UTC events solve different parts of the task.