Steamworks SDK 1.64 vendored at extern/steamworks_sdk_164 (headers +
win32 redistributables only; .gitignore trims the rest). Both projects
build with RP412_STEAM; activation stays behind the RP412STEAM=1
environment switch, so plain desktop runs never touch Steam.
L4STEAMTRANSPORT.cpp implements NetTransport on ISteamNetworkingSockets
with FakeIP: SteamNetTransport_Install brings up SteamAPI, relay
network access, and a two-port FakeIP identity (fake port 0 = console
channel, 1 = game mesh), then swaps the process wire; any failure logs
the reason and the game carries on over TCP. Addressing keeps the
engine untouched: all pods share the -net port convention, eggs carry
fakeip:engineport, and the transport alone translates engine ports to
Steam fake ports via the lobby-fed peer table (RegisterPeer). Connect
mirrors the TCP retry-while-refused loop; Receive normalizes message
lanes back into the stream semantics CheckBuffers expects.
Runtime verified on this box: RP412STEAM=1 under AppID 480 came up as
169.254.59.52 (fake ports 32256/32257); without Steam credentials it
falls back to TCP cleanly; default boot logs no Steam lines at all.
steam_api.dll ships in the dist.
Next: the lobby layer (ISteamMatchmaking member data -> RegisterPeer +
egg build + RPL4CONSOLE marshal), which needs a second account to test.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
CydandClaude Fable 5
ff6ec8c56a