It looks like _contextvars has both its own project and is also built as part of pythoncore.vcxproj.

However, _contextvars.vcxproj is not in PCbuild.sln, which means when you build through Visual Studio (rather than with build.bat via pcbuild.proj), you don't get the separate extension module.

And even though it's built into pythoncore.vcxproj, it hasn't been added to PC/config.c, and so it isn't initialised as a regular builtin module.

Yury - is there a specific reason for it to be a standalone module? How much do you think it hurts to have it always loaded into memory, even if it hasn't truly been imported or used?