  Red supergiants (RSG) are key objects for the evolution of massive stars and
their endpoints, but uncertainties in their underlying mass-loss mechanism have
thus far prevented an appropriate framework for massive star evolution. We
analyse an empirical mass loss"kink" feature uncovered by Yang et al., and we
highlight its similarity to hot star radiation-driven wind models and
observations at the optically thin/thick transition point. We motivate a new
RSG mass-loss prescription that depends on the Eddington factor Gamma
(including both a steep L dependence and an inverse steep M dependence). We
subsequently implement this new RSG mass-loss prescription in the stellar
evolution code MESA. We find that our physically motivated mass-loss behaviour
naturally reproduces the Humphreys-Davidson limit without a need for any ad-hoc
tweaks. It also resolves the RSG supernova "problem". We argue that a universal
behaviour of radiation-driven winds across the HR diagram, independent of the
exact source of opacity, is a key feature of the evolution of the most massive
stars.
