I have a net461 console project using non-SDK tooling that references a netstandard1.4 library project that uses SDK tooling.

If I build the solution, then call ResolveReferences on the console project, the ImplicitlyExpandDesignTimeFacades target detects that the referenced netstandard project references System.Runtime, and injects all the net461 facades.

However, if I clean the solution, then call ResolveReferences again, ImplicitlyExpandDesignTimeFacades does not detect the System.Runtime reference, as the referenced project has not yet been built and there is no assembly to inspect.

However, if I do the same thing with a PCL instead of netstandard, ResolveReferences works correctly regardless of whether the project has been built or not.

This is because the logic for injecting the facades checks whether any of the project references have a TargetPlatformIdentifier value of Portable. This is true for PCL projects, not NOT for netstandard. For netstandard projects, the value is Windows, which is clearly incorrect.