square.onLaborTimecardCreated subscribes to labor.timecard.created for the selected seller. It requires TIMECARDS_READ.
Example
automations/square-on-labor-timecard-created.automation.ts
Event
A timecard was created at the start of a shift. The event data contains the complete Timecard object. The signal resolves to the officialSquare.LaborTimecardCreatedEvent payload with type narrowed to labor.timecard.created.