It is possible to debug Cython with mixed-mode debugger, but experience is basically the same as debugging C/C++. You do get the Cython source view when breaking/stepping if C output was generated with --line-directives, but that's the extent of integration.
"Step in" will step into various C utility functions, stack frame will show mangled C function names, and locals will show the actual C locals. It would be nice to support true Cython debugging, that would by default show Cython frames filtered/unmangled
such that you see the original function and variable names, and none of the generated gunk getting in the way.
This is related but orthogonal to project system and editing support: