Interactions

The game's interaction rules — THE plug-in point of this piece. The framework has already validated existence, zone, and range; the policy decides what actually happens: can this door open, what does looting this chest yield, is this button on cooldown. State changes (despawning a pickup via IServerEntities, flipping game state) belong in the implementation. The default accepts everything — the piece works out of the box as a pure "X used Y" event relay. How to implement. Register your policy in DI BEFORE AddCrossplayInteractions (it is a TryAdd seam). Branch on actionId (your verb: open/loot/press/talk) and inspect the target to decide the outcome; do any state change yourself (despawn a pickup, flip a switch, grant loot) and return Accept (optionally with a private result payload for the actor) or Reject with a reason code. The framework has ALREADY checked existence, same-zone, range and payload size, so a policy only implements game rules.

public sealed class DoorAndChestPolicy : IInteractionPolicy
{
    private readonly ILootService _loot;
    public DoorAndChestPolicy(ILootService loot) => _loot = loot;

    public InteractionDecision Decide(
        ISession actor, WorldEntity self, WorldEntity target, ushort actionId, byte[]? data)
    {
        if (actionId == Verbs.Loot && _loot.TryClaim(target.Id, out var item, out _))
            return InteractionDecision.Accept(item);   // private payload back to the actor
        if (actionId == Verbs.Open)
            return InteractionDecision.Accept();        // the EntityInteraction broadcast animates it
        return InteractionDecision.Reject(InteractionNotificationCodes.Rejected);
    }
}

• InteractionDecision Decide(ISession actor, WorldEntity actorEntity, WorldEntity target, ushort actionId, byte[] data)

  Decides an interaction attempt (called on the poll thread, after the framework's gates).