What I wrote with Claude is basically everything else: custom LLVM passes, a hand-written runtime that replaces the Windows calls, a Direct3D 11 to Metal layer and the shader translation! Plus fixing the crashes one by one by iterating and playing. All details are in the Pipeline section of the README if you're interested: https://github.com/adrbn/bo2-mac#pipeline
This is very confusing to read, though:
What I wrote with Claude: [...] a hand-written runtime
To me you have to pick one or the other. Claude has no hands.