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.
TTrain::id() numbers cabs with a local counter, in the order each peer happens
to create them, so it cannot address a vehicle across the session. Neither was
there any way for a player to see what is available to drive.
- network/entities: PeerId (the host is peer 1, remote peers are numbered from
2, so it is a participant rather than a special case) and NetworkEntityId,
plus a registry that numbers the drivable vehicles of the loaded scenario in
name order and resolves ids back to TDynamicObject
- the server owns the numbering and publishes it as VEHICLE_LIST - name, crew
occupancy, crew capacity, AI state, availability - on every change and at
least every 120 frames, out of band so it stays out of the replay backbuffer;
a client binds the received ids to its own copy of the scenario by name
- SERVER_HELLO hands the joining peer its PeerId
- a multiplayer lobby listing that roster, with vehicles taken by other players
shown as such rather than hidden; entering one goes through the existing
entervehicle command, the vehicle is never moved
The lobby lives inside the driver mode instead of a mode of its own: the world
has to keep running while somebody is choosing (a client stops consuming the
server's frames the moment its mode is not a command processor), and the same
screen is what a player needs to change vehicles later on.
Crew occupancy is still derived from the presence of a cab instance; the real
crew model, claim handshake and AI takeover follow in stage 3.
