  We formulate and prove a generalized Albanese property for families of maps
from a smooth curve over an arbitrary field into a commutative group stack. Our
proof, which is mostly self-contained, employs local-to-global techniques and
some new Ext-vanishing results to reduce to the local Cartier self-duality
theorem of Contou-Carrere. As a corollary, we reprove local and global
geometric class field theory with arbitrary ramification.
