PR-D: Replicate building and tree fire starts

CS2MultiplayerMod/Core/Protocol/ProtocolConstants.cs

@@ -4,6 +4,11 @@ public static class ProtocolConstants
     {
         /// <summary>
         /// Wire-format version. Bump when message layout changes to refuse handshake on mismatch.
+        /// v69 adds command id 33, fire ignition: one command per building or tree
+        /// fire start, carrying the target's prefab and position plus the ignition intensity.
+        /// Only starts travel; the burn, the spread and the extinguish run locally on every
+        /// machine, the same start-only shape as disaster events. A v68 peer does not know
+        /// id 33, so the bump refuses it at the handshake instead of dropping its fires silently.
         /// v65 adds the barrier-only Begin stage: a join streams its world only to whoever joined,
         /// and every other peer crosses the same barrier without being sent or installing one.
         /// v65 also widens the accepted range of a course endpoint's split position. A
@@ -221,7 +226,7 @@ public static class ProtocolConstants
         // v66 adds bounded display-only hover geometry to player presence updates.
         // v68 batches one brush frame so dense tree strokes do not overflow or trickle in.
         // Object-brush display markers are also excluded from terrain synchronization.
-        public const int ProtocolVersion = 68;
+        public const int ProtocolVersion = 69;
 
         /// <summary>
         /// Hard cap on a single payload, guarding against corrupt length prefixes.

CS2MultiplayerMod/Game/MultiplayerService/GameplayCommandRegistry.cs

@@ -27,6 +27,7 @@ internal static class GameplayCommandRegistry
             GrowableLifecycleCommand.Id,
             ModTypeTableCommand.Id, ModStateCommand.Id,
             ObjectPlacementBatchCommand.Id, ObjectDeleteBatchCommand.Id,
+            FireIgniteCommand.Id,
         };
 
         internal static void Register(MultiplayerSession session)
@@ -73,6 +74,7 @@ internal static string Name(ushort id)
                 case ModStateCommand.Id: return "mod-state";
                 case ObjectPlacementBatchCommand.Id: return "object-place-batch";
                 case ObjectDeleteBatchCommand.Id: return "object-delete-batch";
+                case FireIgniteCommand.Id: return "fire-ignite";
                 default: return "unknown";
             }
         }

CS2MultiplayerMod/Game/Sync/Commands/Simulation/FireIgniteCommand.cs

@@ -0,0 +1,114 @@
+using CS2MultiplayerMod.Core.Protocol;
+using CS2MultiplayerMod.Core.Sync;
+
+namespace CS2MultiplayerMod.Game.Sync.Commands
+{
+    /// <summary>
+    /// "Something caught fire, here, this strongly." Carries a fire start the receiving
+    /// game cannot derive for itself - which building or tree ignited and how hard -
+    /// and never the burn itself. Each machine then runs the fire with its own
+    /// simulation (escalation, spread, rescue, extinguish), so one small message covers
+    /// a fire of any length. Same start-only shape as <see cref="DisasterEventCommand"/>.
+    ///
+    /// Only starts travel, in both directions: every machine rolls its own ignitions
+    /// and reports them, so both cities converge on the union of fires. Ends stay local:
+    /// each simulation extinguishes on its own clock, and the damage left behind is
+    /// already host-authoritative through the growable condition sync.
+    /// </summary>
+    public sealed class FireIgniteCommand : ISimulationCommand
+    {
+        public const ushort Id = 33;
+        public const int MaxEncodedBytes = 256;
+
+        /// <summary>
+        /// Ceiling on the ignition intensity. The game's own range is small; this only
+        /// stops a forged unsurvivable inferno, it never constrains a real fire.
+        /// </summary>
+        public const float MaxIntensityValue = 1000f;
+
+        /// <summary>Name of the ignited building or tree prefab, resolved locally by the receiver.</summary>
+        public string PrefabName;
+
+        /// <summary>World position of the ignited target (buildings do not move).</summary>
+        public float X, Y, Z;
+
+        /// <summary>Ignition strength as the sender's simulation rolled it.</summary>
+        public float Intensity;
+
+        public ushort CommandId => Id;
+
+        public void Write(NetworkWriter writer)
+        {
+            ValidateForWrite();
+            writer.WriteString(PrefabName);
+            writer.WriteFloat(X); writer.WriteFloat(Y); writer.WriteFloat(Z);
+            writer.WriteFloat(Intensity);
+        }
+
+        public void Read(NetworkReader reader)
+        {
+            PrefabName = WireGuard.ReadName(reader);
+            X = WireGuard.ReadCoordinate(reader);
+            Y = WireGuard.ReadCoordinate(reader);
+            Z = WireGuard.ReadCoordinate(reader);
+            Intensity = ReadIntensity(reader);
+
+            if (reader.Remaining != 0)
+                throw new ProtocolException("Trailing bytes in fire ignite: " + reader.Remaining + ".");
+        }
+
+        public byte[] Encode()
+        {
+            var writer = new NetworkWriter(96);
+            Write(writer);
+            if (writer.Length > MaxEncodedBytes)
+                throw new ProtocolException("Fire ignite exceeds the " + MaxEncodedBytes + "-byte cap.");
+            return writer.ToArray();
+        }
+
+        public static FireIgniteCommand Decode(byte[] body)
+        {
+            if (body == null)
+                throw new ProtocolException("Missing fire ignite body.");
+            if (body.Length > MaxEncodedBytes)
+                throw new ProtocolException("Fire ignite exceeds the " + MaxEncodedBytes + "-byte cap.");
+            var command = new FireIgniteCommand();
+            command.Read(new NetworkReader(body));
+            return command;
+        }
+
+        private void ValidateForWrite()
+        {
+            if (string.IsNullOrEmpty(PrefabName) || PrefabName.Length > WireGuard.MaxNameLength)
+                throw new ProtocolException("Invalid fire target prefab name.");
+            for (int i = 0; i < PrefabName.Length; i++)
+                if (char.IsControl(PrefabName[i]))
+                    throw new ProtocolException("Control character in fire target prefab name.");
+            ValidateCoordinate(X, "X");
+            ValidateCoordinate(Y, "Y");
+            ValidateCoordinate(Z, "Z");
+            ValidateIntensity(Intensity);
+        }
+
+        private static float ReadIntensity(NetworkReader reader)
+        {
+            float value = WireGuard.ReadFinite(reader);
+            ValidateIntensity(value);
+            return value;
+        }
+
+        private static void ValidateIntensity(float value)
+        {
+            if (float.IsNaN(value) || float.IsInfinity(value) ||
+                value < 0f || value > MaxIntensityValue)
+                throw new ProtocolException("Implausible fire intensity: " + value + ".");
+        }
+
+        private static void ValidateCoordinate(float value, string label)
+        {
+            if (float.IsNaN(value) || float.IsInfinity(value) ||
+                value < -WireGuard.MaxCoordinate || value > WireGuard.MaxCoordinate)
+                throw new ProtocolException("Invalid fire coordinate " + label + ".");
+        }
+    }
+}

CS2MultiplayerMod/Game/Sync/Systems/Pipeline/SyncRealizeSystem.cs

@@ -26,6 +26,7 @@ public partial class SyncRealizeSystem : GameSystemBase
         private RouteSyncSystem _routeSync;
         private TilePurchaseSyncSystem _tileSync;
         private DisasterSyncSystem _disasterSync;
+        private FireSyncSystem _fireSync;
         private GrowableSyncSystem _growableSync;
         private Mods.ModStateSyncSystem _modStateSync;
 
@@ -45,6 +46,7 @@ protected override void OnCreate()
             _routeSync = World.GetOrCreateSystemManaged<RouteSyncSystem>();
             _tileSync = World.GetOrCreateSystemManaged<TilePurchaseSyncSystem>();
             _disasterSync = World.GetOrCreateSystemManaged<DisasterSyncSystem>();
+            _fireSync = World.GetOrCreateSystemManaged<FireSyncSystem>();
             _growableSync = World.GetOrCreateSystemManaged<GrowableSyncSystem>();
             _modStateSync = World.GetOrCreateSystemManaged<Mods.ModStateSyncSystem>();
         }
@@ -179,6 +181,9 @@ protected override void OnUpdate()
                 // dependency - but they must still be created here: the game's event initialization
                 // runs later this frame and only ever looks at freshly Created events.
                 Step("DisasterSync", _disasterSync.RealizePending);
+                // A realized ignition only sets OnFire on an existing building or tree -
+                // no definitions, no terrain - so it rides the same slot as disasters.
+                Step("FireSync", _fireSync.RealizePending);
                 // Last: what another mod stores is stored against a road, a junction or a building,
                 // so everything that could still be creating one this frame has to have run. A
                 // closure whose carrier is genuinely still in the backlog waits in its own hold