Claims a shift for the authenticated employee. There is no employee parameter: the claimant is always the caller, and a caller with no employee record gets claimant_not_an_employee. When the shift requires approval the claim is created pending and the employee is not assigned. Otherwise the claim is approved and the employee is assigned in the same request. A recurring occurrence is identified by a composite ID, <definitionUuid>_<Ymd\THis>, and can be claimed once it has a row; an occurrence that has no row yet is not claimable and returns shift_not_claimable. A success body carries the claim only, with no evaluation data. Claiming fails with open_shifts_disabled while Open Shifts is off.

OAuth Scopes: scheduling:shifts.write