tmux.Session.SetUpdateEnvironment

SetUpdateEnvironment replaces the complete "update-environment" session option array with SparseArraystring, preserving holes and empty values (tmux 3.2a or later). Read it with SessionOptionValues.UpdateEnvironment from Session.Options ; Session.UnsetOption restores inheritance or the global default. Replacement is not atomic: the result reports confirmed writes, and failures stop without rollback. Serialize concurrent replacement of the same target and option.