A manager declines a pending claim. The claim stays listed as declined with the resolution reason manager_denied, and that employee cannot claim the shift again. Declining runs no evaluation and needs no open spot, so it works on a shift that is full, started, or no longer published. A claim the caller cannot see answers 404 exactly as a claim that does not exist, and a caller who can see it but may not edit the shift gets 403. Declining fails with open_shifts_disabled while Open Shifts is off.

OAuth Scopes: scheduling:shifts.write