PyDev.Debugger

Not in that sense. The VSCode extension didn't fork the debugger in question - it took the original code verbatim, and simply wrapped it into a DAP adapter. Ironically, when we rewrote the Python debugger later, we did the same exact thing with pydevd (https://github.com/fabioz/PyDev.Debugger), and for the same reasons - why reinvent the wheel when you can take an existing one that's already better than anything you have? It's also better for the ecosystem, since improvements all flow upstream.

Ha, I'm just working on integrating the `pydev.debugger` code reloading into `debugpy` (so that the code reloading from the PyDev debugger will be available for Python-VSCode debugger users too). The in-memory reloading (which may be seen at: https://github.com/fabioz/PyDev.Debugger/blob/main/_pydevd_b...) unfortunately doesn't work all the time (fixing the references at runtime in Python is difficult), but it works well enough for the cases where you have a simple function and change it (that file does explain some of the issues that the reloading faces). One major issue is that after doing the reload, you need to get out of the function and then back into it to see the difference -- so, if you're stopped in the function in a breakpoint, it's not possible to simply drop the function and restart it as Python itself doesn't support that...