  This note derives the stochastic differential equations and partial
differential equation of general hybrid quantum--classical dynamics from the
theory of continuous measurement and general (non-Markovian) feedback. The
advantage of this approach is an explicit parameterization, without additional
positivity constraints. The construction also neatly separates the different
effects: how the quantum influences the classical and how the classical
influences the quantum. This modular presentation gives a better intuition of
what to expect from hybrid dynamics, especially when used to construct possibly
fundamental theories.
