Graphical languages of various sorts are increasingly used for the specification and the design of high-integrity real-time systems. Their coverage however does not extend with as much success to automated source code generation. Several hurdles cause the model-to-code translation to often lapse in the preservation of the desired semantics. This paper illustrates the choices we have made to provide the HRT-UML design method with an automated Ravenscar-compliant source code generation engine. Compliance with the Ravenscar computational model warrants static analysability of the source code and predictability of execution. By elevating this compliance to the design stage, we earn semantic preservation across the whole development process.