Two weeks advance notice, or you get paid more.
San Francisco is the latest American jurisdiction to find an answer to what are called, here in Britain, “zero hours contracts”. As reported by Claire Zillman in Fortune:
[San Francisco’s Board of Supervisors, which is also the city council of that city+county] voted unanimously on Tuesday [25 November] afternoon in favor of measures aimed at giving retail staffers more predictable schedules and access to extra hours. The ordinances will require businesses to post workers’ schedules at least two weeks in advance. Workers will receive compensation for last-minute schedule changes, “on-call” hours, and instances in which they’re sent home before completing their assigned shifts.