Three things stood in the way of two people sharing a cab and of a client not
being able to reach past its own vehicle.
Vehicle commands were addressed by TTrain::id(), which every peer hands out
locally from its own counter, so the same number means a different vehicle on
a different peer. Commands now travel with the session wide NetworkEntityId
and are translated back to the local cab on arrival; outside of multiplayer
the registry is empty and both directions are a no-op, so singleplayer is
untouched.
A client could send any command it liked, including setweather, queueevent or
spawntrainset. The server now validates every incoming command: a player may
work the controls of the vehicle whose crew they are on and nothing else, and
world wide commands stay with the host until dispatcher roles exist. The
source is stamped by the server, never taken from what the peer sent, and
rejections are logged once per peer/command instead of every frame. Host input
runs through the very same validation, just without the transport.
Continuous commands were tracked per command and recipient only, so with two
people in one cab the release sent by one of them cancelled the other one's
hold. command_data now carries the source peer and the active set is keyed by
{source, recipient, command}.
Also: a client asking to quit no longer replicates quitsimulation, which would
have shut down everybody else's session.
A vehicle is not owned by one player: two people share a cab, so the session
needs a crew relation rather than an owner field. The server keeps it and is
the only one allowed to change it.
- network/session: vehicle_crew { entity_id, crew, ai_before_claim } and a
crew_registry holding the roster. the host goes through exactly the same
path as a remote peer (claim -> crew -> grant), only without transport
- CLAIM_VEHICLE / CLAIM_GRANTED / CLAIM_DENIED / LEAVE_VEHICLE / CREW_UPDATE;
the server validates the vehicle exists, is present in the scenario and has
room in the crew, and answers a refusal with a reason the lobby shows
- the cab of a claimed vehicle is created by the authority posting the
ordinary replicated entervehicle, so every peer builds it and the vehicle is
never moved. the claiming peer only walks in once the cab appears locally
- AI transitions follow the crew size: 0 -> 1 remembers whether an AI was
really driving and takes the vehicle over, 1 -> 2 and 2 -> 1 change nothing,
1 -> 0 hands the vehicle back but only if there was an AI driver to begin
with. driver mode no longer fires aidriverdisable of its own in multiplayer
- losing a connection removes that peer from every crew it was on; a vehicle
with somebody still on board carries on untouched
- the lobby lists who is on board, offers "join crew" for a vehicle another
player already occupies, and lets a player step off
The AI and cab handling runs as a reconciliation pass rather than as edge
triggered actions, so a request that has not taken effect yet (the cab needs a
frame to appear) is simply repeated, with a cooldown to keep it off the wire.
