The Client is always right

- Fixed edge points getting wiped near where two graphs just merged
- Fixed edge points not migrating to modified edges properly
- Graph edge points are now synched by netcode (signals, stations)
- Fixed incorrect stopping position when approaching station manually while the train is still moving backwards
- Fixed single-group edges not being deserialised correctly
- Edge data is now synched by netcode
- Signal edge groups are now synched by netcode
- Signal block indication can now get necessary information client-side

src/main/java/com/simibubi/create/content/logistics/trains/GlobalRailwayManager.java

@@ -46,6 +46,7 @@ public class GlobalRailwayManager {
 			loadTrackData(serverPlayer.getServer());
 			trackNetworks.values()
 				.forEach(g -> sync.sendFullGraphTo(g, serverPlayer));
+			sync.sendEdgeGroups(signalEdgeGroups.keySet(), serverPlayer);
 		}
 	}
 
@@ -150,21 +151,21 @@ public class GlobalRailwayManager {
 		for (Train train : trains.values())
 			train.tick(level);
 
-		if (AllKeys.isKeyDown(GLFW.GLFW_KEY_H)) {
+		if (AllKeys.isKeyDown(GLFW.GLFW_KEY_H) && AllKeys.altDown())
 			trackNetworks.values()
 				.forEach(TrackGraph::debugViewSignalData);
-		}
-		if (AllKeys.isKeyDown(GLFW.GLFW_KEY_J) && AllKeys.altDown()) {
+		if (AllKeys.isKeyDown(GLFW.GLFW_KEY_J) && AllKeys.altDown())
 			trackNetworks.values()
 				.forEach(TrackGraph::debugViewNodes);
-		}
 	}
 
 	public void clientTick() {
-		if (AllKeys.isKeyDown(GLFW.GLFW_KEY_J) && !AllKeys.altDown()) {
+		if (AllKeys.isKeyDown(GLFW.GLFW_KEY_H) && !AllKeys.altDown())
+			trackNetworks.values()
+				.forEach(TrackGraph::debugViewSignalData);
+		if (AllKeys.isKeyDown(GLFW.GLFW_KEY_J) && !AllKeys.altDown())
 			trackNetworks.values()
 				.forEach(TrackGraph::debugViewNodes);
-		}
 	}
 
 }

src/main/java/com/simibubi/create/content/logistics/trains/TrackGraph.java

@@ -75,6 +75,7 @@ public class TrackGraph {
 	public <T extends TrackEdgePoint> void addPoint(EdgePointType<T> type, T point) {
 		edgePoints.put(type, point);
 		EdgePointManager.onEdgePointAdded(this, point, type);
+		Create.RAILWAYS.sync.pointAdded(this, point);
 		markDirty();
 	}
 
@@ -91,6 +92,7 @@ public class TrackGraph {
 		if (removed == null)
 			return null;
 		EdgePointManager.onEdgePointRemoved(this, removed, type);
+		Create.RAILWAYS.sync.pointRemoved(this, removed);
 		markDirty();
 		return removed;
 	}
@@ -197,12 +199,13 @@ public class TrackGraph {
 			TrackNode n2 = toOther.locateNode(node2.location);
 			if (n1 == null || n2 == null)
 				return;
-			toOther.putConnection(n1, n2, edge);
-			Create.RAILWAYS.sync.edgeAdded(toOther, n1, n2, edge);
+			if (toOther.putConnection(n1, n2, edge)) {
+				Create.RAILWAYS.sync.edgeAdded(toOther, n1, n2, edge);
+				Create.RAILWAYS.sync.edgeDataChanged(toOther, n1, n2, edge);
+			}
 		}));
 
-		edgePoints.transferAll(toOther.edgePoints);
-
+		edgePoints.transferAll(toOther, toOther.edgePoints);
 		nodes.clear();
 		connectionsByNode.clear();
 
@@ -325,9 +328,13 @@ public class TrackGraph {
 			map2.remove(node1);
 	}
 
-	public void putConnection(TrackNode node1, TrackNode node2, TrackEdge edge) {
-		connectionsByNode.computeIfAbsent(node1, n -> new IdentityHashMap<>())
-			.put(node2, edge);
+	public boolean putConnection(TrackNode node1, TrackNode node2, TrackEdge edge) {
+		Map<TrackNode, TrackEdge> connections = connectionsByNode.computeIfAbsent(node1, n -> new IdentityHashMap<>());
+		if (connections.containsKey(node2) && connections.get(node2)
+			.getEdgeData()
+			.hasPoints())
+			return false;
+		return connections.put(node2, edge) == null;
 	}
 
 	public void markDirty() {

src/main/java/com/simibubi/create/content/logistics/trains/TrackGraphPacket.java

@@ -0,0 +1,26 @@
+package com.simibubi.create.content.logistics.trains;
+
+import java.util.UUID;
+import java.util.function.Supplier;
+
+import com.simibubi.create.CreateClient;
+import com.simibubi.create.foundation.networking.SimplePacketBase;
+
+import net.minecraftforge.network.NetworkEvent.Context;
+
+public abstract class TrackGraphPacket extends SimplePacketBase {
+
+	public UUID graphId;
+	public boolean packetDeletesGraph;
+
+	@Override
+	public void handle(Supplier<Context> context) {
+		context.get()
+			.enqueueWork(() -> handle(CreateClient.RAILWAYS, CreateClient.RAILWAYS.getOrCreateGraph(graphId)));
+		context.get()
+			.setPacketHandled(true);
+	}
+
+	protected abstract void handle(GlobalRailwayManager manager, TrackGraph graph);
+
+}

src/main/java/com/simibubi/create/content/logistics/trains/TrackGraphSync.java

@@ -1,43 +1,37 @@
 package com.simibubi.create.content.logistics.trains;
 
 import java.util.ArrayList;
-import java.util.HashMap;
+import java.util.Collection;
 import java.util.List;
-import java.util.Map;
-import java.util.Map.Entry;
 import java.util.Set;
 import java.util.UUID;
-import java.util.function.Supplier;
 
 import javax.annotation.Nullable;
 
+import com.google.common.collect.ImmutableList;
 import com.simibubi.create.Create;
-import com.simibubi.create.CreateClient;
+import com.simibubi.create.content.logistics.trains.management.edgePoint.EdgePointType;
+import com.simibubi.create.content.logistics.trains.management.signal.SignalEdgeGroupPacket;
+import com.simibubi.create.content.logistics.trains.management.signal.TrackEdgePoint;
 import com.simibubi.create.foundation.networking.AllPackets;
-import com.simibubi.create.foundation.networking.SimplePacketBase;
 import com.simibubi.create.foundation.utility.Couple;
 import com.simibubi.create.foundation.utility.Pair;
-import com.simibubi.create.foundation.utility.VecHelper;
 
-import net.minecraft.core.BlockPos;
-import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.world.phys.Vec3;
-import net.minecraftforge.network.NetworkEvent.Context;
 import net.minecraftforge.network.PacketDistributor;
 
 public class TrackGraphSync {
 
-	List<RailGraphSyncPacket> queuedPackets = new ArrayList<>();
+	List<TrackGraphPacket> queuedPackets = new ArrayList<>();
 
 	public void serverTick() {
-		finish();
+		flushGraphPacket(null);
 		if (queuedPackets.isEmpty())
 			return;
-		for (RailGraphSyncPacket packet : queuedPackets) {
-			if (packet.delete || Create.RAILWAYS.trackNetworks.containsKey(packet.graphId)) {
-				AllPackets.channel.send(PacketDistributor.ALL.noArg(), packet);
-			}
+		for (TrackGraphPacket packet : queuedPackets) {
+			if (!packet.packetDeletesGraph && !Create.RAILWAYS.trackNetworks.containsKey(packet.graphId))
+				continue;
+			AllPackets.channel.send(PacketDistributor.ALL.noArg(), packet);
 		}
 		queuedPackets.clear();
 	}
@@ -45,21 +39,31 @@ public class TrackGraphSync {
 	//
 
 	public void nodeAdded(TrackGraph graph, TrackNode node) {
-		flushPacket(graph.id);
-		currentPacket.addedNodes.put(node.getNetId(), Pair.of(node.getLocation(), node.getNormal()));
+		flushGraphPacket(graph.id);
+		currentGraphSyncPacket.addedNodes.put(node.getNetId(), Pair.of(node.getLocation(), node.getNormal()));
 	}
 
 	public void edgeAdded(TrackGraph graph, TrackNode node1, TrackNode node2, TrackEdge edge) {
-		flushPacket(graph.id);
-		currentPacket.addedEdges.add(Pair.of(Couple.create(node1.getNetId(), node2.getNetId()), edge));
+		flushGraphPacket(graph.id);
+		currentGraphSyncPacket.addedEdges.add(Pair.of(Couple.create(node1.getNetId(), node2.getNetId()), edge));
+	}
+
+	public void pointAdded(TrackGraph graph, TrackEdgePoint point) {
+		flushGraphPacket(graph.id);
+		currentGraphSyncPacket.addedEdgePoints.add(point);
+	}
+
+	public void pointRemoved(TrackGraph graph, TrackEdgePoint point) {
+		flushGraphPacket(graph.id);
+		currentGraphSyncPacket.removedEdgePoints.add(point.getId());
 	}
 
 	public void nodeRemoved(TrackGraph graph, TrackNode node) {
-		flushPacket(graph.id);
+		flushGraphPacket(graph.id);
 		int nodeId = node.getNetId();
-		if (currentPacket.addedNodes.remove(nodeId) == null)
-			currentPacket.removedNodes.add(nodeId);
-		currentPacket.addedEdges.removeIf(pair -> {
+		if (currentGraphSyncPacket.addedNodes.remove(nodeId) == null)
+			currentGraphSyncPacket.removedNodes.add(nodeId);
+		currentGraphSyncPacket.addedEdges.removeIf(pair -> {
 			Couple<Integer> ids = pair.getFirst();
 			return ids.getFirst()
 				.intValue() == nodeId
@@ -69,183 +73,104 @@ public class TrackGraphSync {
 	}
 
 	public void graphSplit(TrackGraph graph, Set<TrackGraph> additional) {
-		flushPacket(graph.id);
-		additional.forEach(rg -> currentPacket.splitSubGraphs.put(rg.nodesById.keySet()
+		flushGraphPacket(graph.id);
+		additional.forEach(rg -> currentGraphSyncPacket.splitSubGraphs.put(rg.nodesById.keySet()
 			.stream()
 			.findFirst()
 			.get(), rg.id));
 	}
 
 	public void graphRemoved(TrackGraph graph) {
-		flushPacket(graph.id);
-		currentPacket.delete = true;
-	}
-
-	public void finish() {
-		flushPacket(null);
+		flushGraphPacket(graph.id);
+		currentGraphSyncPacket.packetDeletesGraph = true;
 	}
 
 	//
 
+	public void sendEdgeGroups(Collection<UUID> ids, ServerPlayer player) {
+		AllPackets.channel.send(PacketDistributor.PLAYER.with(() -> player), new SignalEdgeGroupPacket(ids, true));
+	}
+
+	public void edgeGroupCreated(UUID id) {
+		AllPackets.channel.send(PacketDistributor.ALL.noArg(), new SignalEdgeGroupPacket(ImmutableList.of(id), true));
+	}
+
+	public void edgeGroupRemoved(UUID id) {
+		AllPackets.channel.send(PacketDistributor.ALL.noArg(), new SignalEdgeGroupPacket(ImmutableList.of(id), false));
+	}
+
+	//
+
+	public void edgeDataChanged(TrackGraph graph, TrackNode node1, TrackNode node2, TrackEdge edge) {
+		flushGraphPacket(graph.id);
+		currentGraphSyncPacket.syncEdgeData(node1, node2, edge);
+	}
+
+	public void edgeDataChanged(TrackGraph graph, TrackNode node1, TrackNode node2, TrackEdge edge, TrackEdge edge2) {
+		flushGraphPacket(graph.id);
+		currentGraphSyncPacket.syncEdgeData(node1, node2, edge);
+		currentGraphSyncPacket.syncEdgeData(node2, node1, edge2);
+	}
+
 	public void sendFullGraphTo(TrackGraph graph, ServerPlayer player) {
-		RailGraphSyncPacket packet = new RailGraphSyncPacket(graph.id);
+		TrackGraphSyncPacket packet = new TrackGraphSyncPacket(graph.id);
 		int sent = 0;
+
 		for (TrackNode node : graph.nodes.values()) {
-			RailGraphSyncPacket currentPacket = packet;
+			TrackGraphSyncPacket currentPacket = packet;
 			currentPacket.addedNodes.put(node.getNetId(), Pair.of(node.getLocation(), node.getNormal()));
 			if (!graph.connectionsByNode.containsKey(node))
 				continue;
 			graph.connectionsByNode.get(node)
-				.forEach((node2, edge) -> currentPacket.addedEdges
-					.add(Pair.of(Couple.create(node.getNetId(), node2.getNetId()), edge)));
+				.forEach((node2, edge) -> {
+					Couple<Integer> key = Couple.create(node.getNetId(), node2.getNetId());
+					currentPacket.addedEdges.add(Pair.of(key, edge));
+					currentPacket.syncEdgeData(node, node2, edge);
+				});
+
+			if (sent++ < 1000)
+				continue;
+
+			sent = 0;
+			packet = flushAndCreateNew(graph, player, packet);
+		}
+
+		for (EdgePointType<?> type : EdgePointType.TYPES.values()) {
+			for (TrackEdgePoint point : graph.getPoints(type)) {
+				packet.addedEdgePoints.add(point);
+
+				if (sent++ < 1000)
+					continue;
 
-			if (sent++ > 1000) {
 				sent = 0;
-				AllPackets.channel.send(PacketDistributor.PLAYER.with(() -> player), packet);
-				packet = new RailGraphSyncPacket(graph.id);
+				packet = flushAndCreateNew(graph, player, packet);
 			}
 		}
+
 		if (sent > 0)
-			AllPackets.channel.send(PacketDistributor.PLAYER.with(() -> player), packet);
+			flushAndCreateNew(graph, player, packet);
 	}
 
-	private RailGraphSyncPacket currentPacket;
+	private TrackGraphSyncPacket flushAndCreateNew(TrackGraph graph, ServerPlayer player, TrackGraphSyncPacket packet) {
+		AllPackets.channel.send(PacketDistributor.PLAYER.with(() -> player), packet);
+		packet = new TrackGraphSyncPacket(graph.id);
+		return packet;
+	}
 
-	private void flushPacket(@Nullable UUID graphId) {
-		if (currentPacket != null) {
-			if (currentPacket.graphId.equals(graphId))
+	//
+
+	private TrackGraphSyncPacket currentGraphSyncPacket;
+
+	private void flushGraphPacket(@Nullable UUID graphId) {
+		if (currentGraphSyncPacket != null) {
+			if (currentGraphSyncPacket.graphId.equals(graphId))
 				return;
-			queuedPackets.add(currentPacket);
-			currentPacket = null;
+			queuedPackets.add(currentGraphSyncPacket);
+			currentGraphSyncPacket = null;
 		}
 
 		if (graphId != null)
-			currentPacket = new RailGraphSyncPacket(graphId);
-	}
-
-	public static class RailGraphSyncPacket extends SimplePacketBase {
-
-		UUID graphId;
-		Map<Integer, Pair<TrackNodeLocation, Vec3>> addedNodes;
-		List<Pair<Couple<Integer>, TrackEdge>> addedEdges;
-		List<Integer> removedNodes;
-		Map<Integer, UUID> splitSubGraphs;
-		boolean delete;
-
-		public RailGraphSyncPacket(UUID graphId) {
-			this.graphId = graphId;
-			addedNodes = new HashMap<>();
-			addedEdges = new ArrayList<>();
-			removedNodes = new ArrayList<>();
-			splitSubGraphs = new HashMap<>();
-			delete = false;
-		}
-
-		public RailGraphSyncPacket(FriendlyByteBuf buffer) {
-			int size;
-
-			graphId = buffer.readUUID();
-			delete = buffer.readBoolean();
-
-			if (delete)
-				return;
-
-			addedNodes = new HashMap<>();
-			addedEdges = new ArrayList<>();
-			removedNodes = new ArrayList<>();
-			splitSubGraphs = new HashMap<>();
-
-			size = buffer.readVarInt();
-			for (int i = 0; i < size; i++)
-				removedNodes.add(buffer.readVarInt());
-
-			size = buffer.readVarInt();
-			for (int i = 0; i < size; i++)
-				addedNodes.put(buffer.readVarInt(),
-					Pair.of(TrackNodeLocation.fromPackedPos(buffer.readBlockPos()), VecHelper.read(buffer)));
-
-			size = buffer.readVarInt();
-			for (int i = 0; i < size; i++)
-				addedEdges.add(Pair.of(Couple.create(buffer::readVarInt), TrackEdge.read(buffer)));
-
-			size = buffer.readVarInt();
-			for (int i = 0; i < size; i++)
-				splitSubGraphs.put(buffer.readVarInt(), buffer.readUUID());
-		}
-
-		@Override
-		public void write(FriendlyByteBuf buffer) {
-
-			buffer.writeUUID(graphId);
-			buffer.writeBoolean(delete);
-			if (delete)
-				return;
-
-			buffer.writeVarInt(removedNodes.size());
-			removedNodes.forEach(buffer::writeVarInt);
-
-			buffer.writeVarInt(addedNodes.size());
-			addedNodes.forEach((node, loc) -> {
-				buffer.writeVarInt(node);
-				buffer.writeBlockPos(new BlockPos(loc.getFirst()));
-				VecHelper.write(loc.getSecond(), buffer);
-			});
-
-			buffer.writeVarInt(addedEdges.size());
-			addedEdges.forEach(pair -> {
-				pair.getFirst()
-					.forEach(buffer::writeVarInt);
-				pair.getSecond()
-					.write(buffer);
-			});
-
-			buffer.writeVarInt(splitSubGraphs.size());
-			splitSubGraphs.forEach((node, uuid) -> {
-				buffer.writeVarInt(node);
-				buffer.writeUUID(uuid);
-			});
-		}
-
-		@Override
-		public void handle(Supplier<Context> context) {
-			context.get()
-				.enqueueWork(() -> {
-					GlobalRailwayManager manager = CreateClient.RAILWAYS;
-					TrackGraph railGraph = manager.getOrCreateGraph(graphId);
-
-					if (delete) {
-						manager.removeGraph(railGraph);
-						return;
-					}
-
-					for (int nodeId : removedNodes) {
-						TrackNode node = railGraph.getNode(nodeId);
-						if (node != null)
-							railGraph.removeNode(null, node.getLocation());
-					}
-
-					for (Entry<Integer, Pair<TrackNodeLocation, Vec3>> entry : addedNodes.entrySet()) {
-						Integer nodeId = entry.getKey();
-						Pair<TrackNodeLocation, Vec3> nodeLocation = entry.getValue();
-						railGraph.loadNode(nodeLocation.getFirst(), nodeId, nodeLocation.getSecond());
-					}
-
-					for (Pair<Couple<Integer>, TrackEdge> pair : addedEdges) {
-						Couple<TrackNode> nodes = pair.getFirst()
-							.map(railGraph::getNode);
-						if (nodes.getFirst() != null && nodes.getSecond() != null)
-							railGraph.putConnection(nodes.getFirst(), nodes.getSecond(), pair.getSecond());
-					}
-
-					if (!splitSubGraphs.isEmpty())
-						railGraph.findDisconnectedGraphs(splitSubGraphs)
-							.forEach(manager::putGraph);
-
-				});
-			context.get()
-				.setPacketHandled(true);
-		}
-
+			currentGraphSyncPacket = new TrackGraphSyncPacket(graphId);
 	}
 
 }

src/main/java/com/simibubi/create/content/logistics/trains/TrackGraphSyncPacket.java

@@ -0,0 +1,243 @@
+package com.simibubi.create.content.logistics.trains;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Objects;
+import java.util.UUID;
+
+import com.simibubi.create.content.logistics.trains.management.edgePoint.EdgePointType;
+import com.simibubi.create.content.logistics.trains.management.signal.EdgeData;
+import com.simibubi.create.content.logistics.trains.management.signal.TrackEdgePoint;
+import com.simibubi.create.foundation.utility.Couple;
+import com.simibubi.create.foundation.utility.Pair;
+import com.simibubi.create.foundation.utility.VecHelper;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.network.FriendlyByteBuf;
+import net.minecraft.world.phys.Vec3;
+
+public class TrackGraphSyncPacket extends TrackGraphPacket {
+
+	Map<Integer, Pair<TrackNodeLocation, Vec3>> addedNodes;
+	List<Pair<Couple<Integer>, TrackEdge>> addedEdges;
+	List<Integer> removedNodes;
+	List<TrackEdgePoint> addedEdgePoints;
+	List<UUID> removedEdgePoints;
+	Map<Integer, UUID> splitSubGraphs;
+	Map<Couple<Integer>, Pair<Integer, List<UUID>>> updatedEdgeData;
+
+	static final int NULL_GROUP = 0, PASSIVE_GROUP = 1, GROUP = 2;
+
+	public TrackGraphSyncPacket(UUID graphId) {
+		this.graphId = graphId;
+		addedNodes = new HashMap<>();
+		addedEdges = new ArrayList<>();
+		removedNodes = new ArrayList<>();
+		addedEdgePoints = new ArrayList<>();
+		removedEdgePoints = new ArrayList<>();
+		updatedEdgeData = new HashMap<>();
+		splitSubGraphs = new HashMap<>();
+		packetDeletesGraph = false;
+	}
+
+	public TrackGraphSyncPacket(FriendlyByteBuf buffer) {
+		int size;
+
+		graphId = buffer.readUUID();
+		packetDeletesGraph = buffer.readBoolean();
+
+		if (packetDeletesGraph)
+			return;
+
+		addedNodes = new HashMap<>();
+		addedEdges = new ArrayList<>();
+		addedEdgePoints = new ArrayList<>();
+		removedEdgePoints = new ArrayList<>();
+		removedNodes = new ArrayList<>();
+		splitSubGraphs = new HashMap<>();
+		updatedEdgeData = new HashMap<>();
+
+		size = buffer.readVarInt();
+		for (int i = 0; i < size; i++)
+			removedNodes.add(buffer.readVarInt());
+
+		size = buffer.readVarInt();
+		for (int i = 0; i < size; i++)
+			addedNodes.put(buffer.readVarInt(),
+				Pair.of(TrackNodeLocation.fromPackedPos(buffer.readBlockPos()), VecHelper.read(buffer)));
+
+		size = buffer.readVarInt();
+		for (int i = 0; i < size; i++)
+			addedEdges.add(Pair.of(Couple.create(buffer::readVarInt), TrackEdge.read(buffer)));
+
+		size = buffer.readVarInt();
+		for (int i = 0; i < size; i++)
+			addedEdgePoints.add(EdgePointType.read(buffer));
+
+		size = buffer.readVarInt();
+		for (int i = 0; i < size; i++)
+			removedEdgePoints.add(buffer.readUUID());
+
+		size = buffer.readVarInt();
+		for (int i = 0; i < size; i++) {
+			ArrayList<UUID> list = new ArrayList<>();
+			Couple<Integer> key = Couple.create(buffer::readInt);
+			Pair<Integer, List<UUID>> entry = Pair.of(buffer.readVarInt(), list);
+			int size2 = buffer.readVarInt();
+			for (int j = 0; j < size2; j++)
+				list.add(buffer.readUUID());
+			updatedEdgeData.put(key, entry);
+		}
+
+		size = buffer.readVarInt();
+		for (int i = 0; i < size; i++)
+			splitSubGraphs.put(buffer.readVarInt(), buffer.readUUID());
+	}
+
+	@Override
+	public void write(FriendlyByteBuf buffer) {
+
+		buffer.writeUUID(graphId);
+		buffer.writeBoolean(packetDeletesGraph);
+		if (packetDeletesGraph)
+			return;
+
+		buffer.writeVarInt(removedNodes.size());
+		removedNodes.forEach(buffer::writeVarInt);
+
+		buffer.writeVarInt(addedNodes.size());
+		addedNodes.forEach((node, loc) -> {
+			buffer.writeVarInt(node);
+			buffer.writeBlockPos(new BlockPos(loc.getFirst()));
+			VecHelper.write(loc.getSecond(), buffer);
+		});
+
+		buffer.writeVarInt(addedEdges.size());
+		addedEdges.forEach(pair -> {
+			pair.getFirst()
+				.forEach(buffer::writeVarInt);
+			pair.getSecond()
+				.write(buffer);
+		});
+
+		buffer.writeVarInt(addedEdgePoints.size());
+		addedEdgePoints.forEach(ep -> ep.write(buffer));
+
+		buffer.writeVarInt(removedEdgePoints.size());
+		removedEdgePoints.forEach(buffer::writeUUID);
+
+		buffer.writeVarInt(updatedEdgeData.size());
+		for (Entry<Couple<Integer>, Pair<Integer, List<UUID>>> entry : updatedEdgeData.entrySet()) {
+			entry.getKey()
+				.forEach(buffer::writeInt);
+			Pair<Integer, List<UUID>> pair = entry.getValue();
+			buffer.writeVarInt(pair.getFirst());
+			List<UUID> list = pair.getSecond();
+			buffer.writeVarInt(list.size());
+			list.forEach(buffer::writeUUID);
+		}
+
+		buffer.writeVarInt(splitSubGraphs.size());
+		splitSubGraphs.forEach((node, uuid) -> {
+			buffer.writeVarInt(node);
+			buffer.writeUUID(uuid);
+		});
+	}
+
+	@Override
+	protected void handle(GlobalRailwayManager manager, TrackGraph graph) {
+		if (packetDeletesGraph) {
+			manager.removeGraph(graph);
+			return;
+		}
+
+		for (int nodeId : removedNodes) {
+			TrackNode node = graph.getNode(nodeId);
+			if (node != null)
+				graph.removeNode(null, node.getLocation());
+		}
+
+		for (Entry<Integer, Pair<TrackNodeLocation, Vec3>> entry : addedNodes.entrySet()) {
+			Integer nodeId = entry.getKey();
+			Pair<TrackNodeLocation, Vec3> nodeLocation = entry.getValue();
+			graph.loadNode(nodeLocation.getFirst(), nodeId, nodeLocation.getSecond());
+		}
+
+		for (Pair<Couple<Integer>, TrackEdge> pair : addedEdges) {
+			Couple<TrackNode> nodes = pair.getFirst()
+				.map(graph::getNode);
+			if (nodes.getFirst() != null && nodes.getSecond() != null)
+				graph.putConnection(nodes.getFirst(), nodes.getSecond(), pair.getSecond());
+		}
+
+		for (TrackEdgePoint edgePoint : addedEdgePoints)
+			graph.edgePoints.put(edgePoint.getType(), edgePoint);
+
+		for (UUID uuid : removedEdgePoints)
+			for (EdgePointType<?> type : EdgePointType.TYPES.values())
+				graph.edgePoints.remove(type, uuid);
+
+		handleEdgeData(manager, graph);
+
+		if (!splitSubGraphs.isEmpty())
+			graph.findDisconnectedGraphs(splitSubGraphs)
+				.forEach(manager::putGraph);
+	}
+
+	protected void handleEdgeData(GlobalRailwayManager manager, TrackGraph graph) {
+		for (Entry<Couple<Integer>, Pair<Integer, List<UUID>>> entry : updatedEdgeData.entrySet()) {
+			List<UUID> idList = entry.getValue()
+				.getSecond();
+			int groupType = entry.getValue()
+				.getFirst();
+
+			Couple<TrackNode> nodes = entry.getKey()
+				.map(graph::getNode);
+			if (nodes.either(Objects::isNull))
+				continue;
+			TrackEdge edge = graph.getConnectionsFrom(nodes.getFirst())
+				.get(nodes.getSecond());
+			if (edge == null)
+				continue;
+
+			EdgeData edgeData = new EdgeData();
+			if (groupType == NULL_GROUP)
+				edgeData.singleSignalGroup = null;
+			else if (groupType == PASSIVE_GROUP)
+				edgeData.singleSignalGroup = EdgeData.passiveGroup;
+			else
+				edgeData.singleSignalGroup = idList.get(0);
+
+			List<TrackEdgePoint> points = edgeData.getPoints();
+			edge.edgeData = edgeData;
+
+			for (int i = groupType == GROUP ? 1 : 0; i < idList.size(); i++) {
+				UUID uuid = idList.get(i);
+				for (EdgePointType<?> type : EdgePointType.TYPES.values()) {
+					TrackEdgePoint point = graph.edgePoints.get(type, uuid);
+					if (point == null)
+						continue;
+					points.add(point);
+					break;
+				}
+			}
+		}
+	}
+
+	public void syncEdgeData(TrackNode node1, TrackNode node2, TrackEdge edge) {
+		Couple<Integer> key = Couple.create(node1.getNetId(), node2.getNetId());
+		List<UUID> list = new ArrayList<>();
+		EdgeData edgeData = edge.getEdgeData();
+		int groupType = edgeData.hasSignalBoundaries() ? NULL_GROUP
+			: EdgeData.passiveGroup.equals(edgeData.singleSignalGroup) ? PASSIVE_GROUP : GROUP;
+		if (groupType == GROUP)
+			list.add(edgeData.singleSignalGroup);
+		for (TrackEdgePoint point : edgeData.getPoints())
+			list.add(point.getId());
+		updatedEdgeData.put(key, Pair.of(groupType, list));
+	}
+
+}

src/main/java/com/simibubi/create/content/logistics/trains/TrackSavedData.java

@@ -27,7 +27,7 @@ public class TrackSavedData extends SavedData {
 	}
 
 	private static TrackSavedData load(CompoundTag nbt) {
-		TrackSavedData sd = new TrackSavedData();
+		TrackSavedData sd = new TrackSavedData();//TODO load trains before everything else
 		sd.trackNetworks = new HashMap<>();
 		sd.signalEdgeGroups = new HashMap<>();
 		NBTHelper.iterateCompoundList(nbt.getList("RailGraphs", Tag.TAG_COMPOUND), c -> {

src/main/java/com/simibubi/create/content/logistics/trains/entity/Navigation.java

@@ -94,11 +94,6 @@ public class Navigation {
 			if (waitingForSignal == null)
 				distanceToSignal = Double.MAX_VALUE;
 
-			if (train.getCurrentStation() != null) {
-				int i = 0;
-				i++;
-			}
-
 			if (distanceToSignal > 1 / 16f) {
 				signalScout.node1 = leadingPoint.node1;
 				signalScout.node2 = leadingPoint.node2;

src/main/java/com/simibubi/create/content/logistics/trains/entity/Train.java

@@ -241,10 +241,11 @@ public class Train {
 		if (navigation.destination != null) {
 			boolean recalculate = navigation.distanceToDestination % 100 > 20;
 			boolean imminentRecalculate = navigation.distanceToDestination > 5;
-			navigation.distanceToDestination -= Math.abs(distance);
+			double toSubstract = navigation.destinationBehindTrain ? -distance : distance;
+			navigation.distanceToDestination -= toSubstract;
 			boolean signalMode = navigation.waitingForSignal != null;
 			if (signalMode) {
-				navigation.distanceToSignal -= Math.abs(distance);
+				navigation.distanceToSignal -= toSubstract;
 				recalculate = navigation.distanceToSignal % 100 > 20;
 			}
 			if (recalculate && (signalMode ? navigation.distanceToSignal : navigation.distanceToDestination) % 100 <= 20

src/main/java/com/simibubi/create/content/logistics/trains/management/GlobalStation.java

@@ -9,6 +9,7 @@ import com.simibubi.create.content.logistics.trains.entity.Train;
 import com.simibubi.create.content.logistics.trains.management.signal.SingleTileEdgePoint;
 
 import net.minecraft.nbt.CompoundTag;
+import net.minecraft.network.FriendlyByteBuf;
 
 public class GlobalStation extends SingleTileEdgePoint {
 
@@ -26,6 +27,12 @@ public class GlobalStation extends SingleTileEdgePoint {
 		name = nbt.getString("Name");
 		nearestTrain = new WeakReference<Train>(null);
 	}
+	
+	@Override
+	public void read(FriendlyByteBuf buffer) {
+		super.read(buffer);
+		name = buffer.readUtf();
+	}
 
 	@Override
 	public void write(CompoundTag nbt) {
@@ -33,6 +40,12 @@ public class GlobalStation extends SingleTileEdgePoint {
 		nbt.putString("Name", name);
 	}
 	
+	@Override
+	public void write(FriendlyByteBuf buffer) {
+		super.write(buffer);
+		buffer.writeUtf(name);
+	}
+	
 	public boolean canApproachFrom(TrackNode side) {
 		return isPrimary(side);
 	}

src/main/java/com/simibubi/create/content/logistics/trains/management/StationEditPacket.java

@@ -74,8 +74,11 @@ public class StationEditPacket extends TileEntityConfigurationPacket<StationTile
 
 		if (!name.isBlank()) {
 			GlobalStation station = te.getStation();
-			if (station != null)
+			GraphLocation graphLocation = te.edgePoint.determineGraphLocation();
+			if (station != null && graphLocation != null) {
 				station.name = name;
+				Create.RAILWAYS.sync.pointAdded(graphLocation.graph, station);
+			}
 			Create.RAILWAYS.markTracksDirty();
 		}
 

src/main/java/com/simibubi/create/content/logistics/trains/management/StationScreen.java

@@ -144,6 +144,8 @@ public class StationScreen extends AbstractStationScreen {
 				int trainIconWidth = getTrainIconWidth(imminentTrain);
 				int targetPos = background.width / 2 - trainIconWidth / 2;
 				float f = (float) (imminentTrain.navigation.distanceToDestination / 15f);
+				if (imminentTrain.currentStation.equals(station.getId()))
+					f = 0;
 				trainPosition.startWithValue(targetPos - (targetPos + 5) * f);
 			}
 			return;
@@ -167,15 +169,16 @@ public class StationScreen extends AbstractStationScreen {
 			return;
 		}
 
-		if (train.navigation.destination != station && train.getCurrentStation() != station) {
+		boolean trainAtStation = train.currentStation != null && train.currentStation.equals(station.getId());
+		if (train.navigation.destination != station && !trainAtStation) {
 			leavingAnimation = 80;
 			return;
 		}
 
-		disassembleTrainButton.active = train.getCurrentStation() == station; // TODO te.canAssemble
+		disassembleTrainButton.active = trainAtStation; // TODO te.canAssemble
 		openScheduleButton.active = train.runtime.schedule != null;
 
-		float f = (float) (train.navigation.distanceToDestination / 30f);
+		float f = trainAtStation ? 0 : (float) (train.navigation.distanceToDestination / 30f);
 		trainPosition.setValue(targetPos - (targetPos + trainIconWidth) * f);
 	}
 

src/main/java/com/simibubi/create/content/logistics/trains/management/TrackTargetingBehaviour.java

@@ -68,13 +68,12 @@ public class TrackTargetingBehaviour<T extends TrackEdgePoint> extends TileEntit
 
 	@Override
 	public void read(CompoundTag nbt, boolean clientPacket) {
-		UUID prevId = id;
 		id = nbt.getUUID("Id");
 		targetTrack = NbtUtils.readBlockPos(nbt.getCompound("TargetTrack"));
 		targetDirection = nbt.getBoolean("TargetDirection") ? AxisDirection.POSITIVE : AxisDirection.NEGATIVE;
 		if (nbt.contains("Migrate"))
 			migrationData = nbt.getCompound("Migrate");
-		if (clientPacket && !prevId.equals(id))
+		if (clientPacket)
 			edgePoint = null;
 		super.read(nbt, clientPacket);
 	}
@@ -86,7 +85,6 @@ public class TrackTargetingBehaviour<T extends TrackEdgePoint> extends TileEntit
 
 	public void invalidateEdgePoint(CompoundTag migrationData) {
 		this.migrationData = migrationData;
-		id = UUID.randomUUID();
 		edgePoint = null;
 		tileEntity.sendData();
 	}
@@ -100,14 +98,16 @@ public class TrackTargetingBehaviour<T extends TrackEdgePoint> extends TileEntit
 
 	@SuppressWarnings("unchecked")
 	public T createEdgePoint() {
-		for (TrackGraph trackGraph : Create.RAILWAYS.trackNetworks.values()) { // TODO thread breach
-			T point = trackGraph.getPoint(edgePointType, id);
-			if (point == null)
-				continue;
-			return point;
-		}
+		boolean isClientSide = getWorld().isClientSide;
+		if (migrationData == null || isClientSide)
+			for (TrackGraph trackGraph : Create.RAILWAYS.trackNetworks.values()) { // TODO thread breach
+				T point = trackGraph.getPoint(edgePointType, id);
+				if (point == null)
+					continue;
+				return point;
+			}
 
-		if (getWorld().isClientSide)
+		if (isClientSide)
 			return null;
 		if (!hasValidTrack())
 			return null;
@@ -126,6 +126,10 @@ public class TrackTargetingBehaviour<T extends TrackEdgePoint> extends TileEntit
 		if (edge == null)
 			return null;
 
+		double length = edge.getLength(node1, node2);
+		CompoundTag data = migrationData;
+		migrationData = null;
+
 		EdgeData signalData = edge.getEdgeData();
 		if (signalData.hasPoints()) {
 			for (EdgePointType<?> otherType : EdgePointType.TYPES.values()) {
@@ -147,19 +151,13 @@ public class TrackTargetingBehaviour<T extends TrackEdgePoint> extends TileEntit
 		}
 
 		T point = edgePointType.create();
+		boolean reverseEdge = front || point instanceof SingleTileEdgePoint;
+
+		if (data != null)
+			point.read(data, true);
+
 		point.setId(id);
-
-		if (point instanceof SingleTileEdgePoint step) {
-			point.setLocation(loc.edge, loc.position);
-			if (migrationData != null) {
-				step.read(migrationData, true);
-				migrationData = null;
-				tileEntity.setChanged();
-			}
-		} else
-			point.setLocation(front ? loc.edge : loc.edge.swap(),
-				front ? loc.position : edge.getLength(node1, node2) - loc.position);
-
+		point.setLocation(reverseEdge ? loc.edge : loc.edge.swap(), reverseEdge ? loc.position : length - loc.position);
 		point.tileAdded(getPos(), front);
 		loc.graph.addPoint(edgePointType, point);
 		return point;

src/main/java/com/simibubi/create/content/logistics/trains/management/edgePoint/EdgePointManager.java

@@ -1,5 +1,6 @@
 package com.simibubi.create.content.logistics.trains.management.edgePoint;
 
+import com.simibubi.create.Create;
 import com.simibubi.create.content.logistics.trains.TrackEdge;
 import com.simibubi.create.content.logistics.trains.TrackGraph;
 import com.simibubi.create.content.logistics.trains.TrackNode;
@@ -22,6 +23,7 @@ public class EdgePointManager {
 			TrackEdge startEdge = startEdges.get(front);
 			startEdge.getEdgeData()
 				.addPoint(node1, node2, startEdge, point);
+			Create.RAILWAYS.sync.edgeDataChanged(graph, node1, node2, startEdge);
 		}
 	}
 
@@ -32,8 +34,11 @@ public class EdgePointManager {
 		startNodes.forEachWithParams((l1, l2) -> {
 			TrackEdge trackEdge = graph.getConnectionsFrom(l1)
 				.get(l2);
+			if (trackEdge == null)
+				return;
 			trackEdge.getEdgeData()
 				.removePoint(l1, l2, trackEdge, point);
+			Create.RAILWAYS.sync.edgeDataChanged(graph, l1, l2, trackEdge);
 		}, startNodes.swap());
 	}
 

src/main/java/com/simibubi/create/content/logistics/trains/management/edgePoint/EdgePointStorage.java

@@ -6,6 +6,7 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.UUID;
 
+import com.simibubi.create.Create;
 import com.simibubi.create.content.logistics.trains.TrackGraph;
 import com.simibubi.create.content.logistics.trains.management.signal.TrackEdgePoint;
 import com.simibubi.create.foundation.utility.NBTHelper;
@@ -54,9 +55,13 @@ public class EdgePointStorage {
 				.forEach(p -> p.tick(graph)));
 	}
 
-	public void transferAll(EdgePointStorage other) {
-		pointsByType.forEach((type, map) -> other.getMap(type)
-			.putAll(map));
+	public void transferAll(TrackGraph target, EdgePointStorage other) {
+		pointsByType.forEach((type, map) -> {
+			other.getMap(type)
+				.putAll(map);
+			map.values()
+				.forEach(ep -> Create.RAILWAYS.sync.pointAdded(target, ep));
+		});
 		pointsByType.clear();
 	}
 
@@ -83,7 +88,7 @@ public class EdgePointStorage {
 			Map<UUID, TrackEdgePoint> map = getMap(type);
 			NBTHelper.iterateCompoundList(list, tag -> {
 				TrackEdgePoint edgePoint = type.create();
-				edgePoint.read(tag);
+				edgePoint.read(tag, false);
 				map.put(edgePoint.getId(), edgePoint);
 			});
 		}

src/main/java/com/simibubi/create/content/logistics/trains/management/edgePoint/EdgePointType.java

@@ -9,6 +9,7 @@ import com.simibubi.create.content.logistics.trains.management.GlobalStation;
 import com.simibubi.create.content.logistics.trains.management.signal.SignalBoundary;
 import com.simibubi.create.content.logistics.trains.management.signal.TrackEdgePoint;
 
+import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.resources.ResourceLocation;
 
 public class EdgePointType<T extends TrackEdgePoint> {
@@ -42,5 +43,13 @@ public class EdgePointType<T extends TrackEdgePoint> {
 	public ResourceLocation getId() {
 		return id;
 	}
+	
+	public static TrackEdgePoint read(FriendlyByteBuf buffer) {
+		ResourceLocation type = buffer.readResourceLocation();
+		EdgePointType<?> edgePointType = TYPES.get(type);
+		TrackEdgePoint point = edgePointType.create();
+		point.read(buffer);
+		return point;
+	}
 
 }

src/main/java/com/simibubi/create/content/logistics/trains/management/signal/EdgeData.java

@@ -101,7 +101,7 @@ public class EdgeData {
 	public static EdgeData read(CompoundTag nbt, TrackGraph graph) {
 		EdgeData data = new EdgeData();
 		if (nbt.contains("SignalGroup"))
-			data.singleSignalGroup = nbt.getUUID("Group");
+			data.singleSignalGroup = nbt.getUUID("SignalGroup");
 		else if (!nbt.contains("PassiveGroup"))
 			data.singleSignalGroup = null;
 

src/main/java/com/simibubi/create/content/logistics/trains/management/signal/SignalBoundary.java

@@ -19,6 +19,7 @@ import net.minecraft.core.BlockPos;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.NbtUtils;
 import net.minecraft.nbt.Tag;
+import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.world.level.LevelAccessor;
 
 public class SignalBoundary extends TrackEdgePoint {
@@ -124,8 +125,11 @@ public class SignalBoundary extends TrackEdgePoint {
 	}
 
 	@Override
-	public void read(CompoundTag nbt) {
-		super.read(nbt);
+	public void read(CompoundTag nbt, boolean migration) {
+		super.read(nbt, migration);
+		
+		if (migration)
+			return;
 
 		sidesToUpdate = Couple.create(true, true);
 		signals = Couple.create(HashSet::new);
@@ -143,6 +147,15 @@ public class SignalBoundary extends TrackEdgePoint {
 		for (int i = 1; i <= 2; i++)
 			sidesToUpdate.set(i == 1, nbt.contains("Update" + i));
 	}
+	
+	@Override
+	public void read(FriendlyByteBuf buffer) {
+		super.read(buffer);
+		for (int i = 1; i <= 2; i++) {
+			if (buffer.readBoolean())
+				groups.set(i == 1, buffer.readUUID());
+		}
+	}
 
 	@Override
 	public void write(CompoundTag nbt) {
@@ -158,5 +171,16 @@ public class SignalBoundary extends TrackEdgePoint {
 			if (sidesToUpdate.get(i == 1))
 				nbt.putBoolean("Update" + i, true);
 	}
+	
+	@Override
+	public void write(FriendlyByteBuf buffer) {
+		super.write(buffer);
+		for (int i = 1; i <= 2; i++) {
+			boolean hasGroup = groups.get(i == 1) != null;
+			buffer.writeBoolean(hasGroup);
+			if (hasGroup)
+				buffer.writeUUID(groups.get(i == 1));
+		}
+	}
 
 }

src/main/java/com/simibubi/create/content/logistics/trains/management/signal/SignalEdgeGroupPacket.java

@@ -0,0 +1,56 @@
+package com.simibubi.create.content.logistics.trains.management.signal;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Map;
+import java.util.UUID;
+import java.util.function.Supplier;
+
+import com.simibubi.create.CreateClient;
+import com.simibubi.create.foundation.networking.SimplePacketBase;
+
+import net.minecraft.network.FriendlyByteBuf;
+import net.minecraftforge.network.NetworkEvent.Context;
+
+public class SignalEdgeGroupPacket extends SimplePacketBase {
+
+	Collection<UUID> ids;
+	boolean add;
+
+	public SignalEdgeGroupPacket(Collection<UUID> ids, boolean add) {
+		this.ids = ids;
+		this.add = add;
+	}
+
+	public SignalEdgeGroupPacket(FriendlyByteBuf buffer) {
+		ids = new ArrayList<>();
+		add = buffer.readBoolean();
+		int size = buffer.readVarInt();
+		for (int i = 0; i < size; i++)
+			ids.add(buffer.readUUID());
+	}
+
+	@Override
+	public void write(FriendlyByteBuf buffer) {
+		buffer.writeBoolean(add);
+		buffer.writeVarInt(ids.size());
+		ids.forEach(buffer::writeUUID);
+	}
+
+	@Override
+	public void handle(Supplier<Context> context) {
+		context.get()
+			.enqueueWork(() -> {
+				Map<UUID, SignalEdgeGroup> signalEdgeGroups = CreateClient.RAILWAYS.signalEdgeGroups;
+				for (UUID id : ids) {
+					if (add)
+						signalEdgeGroups.put(id, new SignalEdgeGroup(id));
+					else
+						signalEdgeGroups.remove(id);
+				}
+			});
+		context.get()
+			.setPacketHandled(true);
+	}
+
+}

src/main/java/com/simibubi/create/content/logistics/trains/management/signal/SignalPropagator.java

@@ -13,6 +13,7 @@ import com.google.common.base.Predicates;
 import com.simibubi.create.Create;
 import com.simibubi.create.content.logistics.trains.TrackEdge;
 import com.simibubi.create.content.logistics.trains.TrackGraph;
+import com.simibubi.create.content.logistics.trains.TrackGraphSync;
 import com.simibubi.create.content.logistics.trains.TrackNode;
 import com.simibubi.create.content.logistics.trains.TrackNodeLocation;
 import com.simibubi.create.content.logistics.trains.entity.Train;
@@ -28,7 +29,9 @@ public class SignalPropagator {
 		for (boolean front : Iterate.trueAndFalse) {
 			if (signal.sidesToUpdate.get(front))
 				continue;
-			Create.RAILWAYS.signalEdgeGroups.remove(signal.groups.get(front));
+			UUID id = signal.groups.get(front);
+			if (Create.RAILWAYS.signalEdgeGroups.remove(id) != null)
+				Create.RAILWAYS.sync.edgeGroupRemoved(id);
 			walkSignals(graph, signal, front, pair -> {
 				TrackNode node1 = pair.getFirst();
 				SignalBoundary boundary = pair.getSecond();
@@ -51,23 +54,30 @@ public class SignalPropagator {
 
 	public static void propagateSignalGroup(TrackGraph graph, SignalBoundary signal, boolean front) {
 		Map<UUID, SignalEdgeGroup> globalGroups = Create.RAILWAYS.signalEdgeGroups;
+		TrackGraphSync sync = Create.RAILWAYS.sync;
+
 		SignalEdgeGroup group = new SignalEdgeGroup(UUID.randomUUID());
 		UUID groupId = group.id;
 		globalGroups.put(groupId, group);
+		sync.edgeGroupCreated(groupId);
 		signal.groups.set(front, groupId);
+		sync.pointAdded(graph, signal);
 
 		walkSignals(graph, signal, front, pair -> {
 			TrackNode node1 = pair.getFirst();
 			SignalBoundary boundary = pair.getSecond();
 			UUID currentGroup = boundary.getGroup(node1);
 			if (currentGroup != null)
-				globalGroups.remove(currentGroup);
+				if (globalGroups.remove(currentGroup) != null)
+					sync.edgeGroupRemoved(currentGroup);
 			boundary.setGroup(node1, groupId);
+			sync.pointAdded(graph, boundary);
 			return true;
 
 		}, signalData -> {
 			if (signalData.singleSignalGroup != null)
-				globalGroups.remove(signalData.singleSignalGroup);
+				if (globalGroups.remove(signalData.singleSignalGroup) != null)
+					sync.edgeGroupRemoved(signalData.singleSignalGroup);
 			signalData.singleSignalGroup = groupId;
 			return true;
 
@@ -85,16 +95,19 @@ public class SignalPropagator {
 		TrackNode node1 = startNodes.get(front);
 		TrackNode node2 = startNodes.get(!front);
 		TrackEdge startEdge = startEdges.get(front);
+		TrackEdge oppositeEdge = startEdges.get(!front);
 
 		if (startEdge == null)
 			return;
 
+		Create.RAILWAYS.sync.edgeDataChanged(graph, node1, node2, startEdge, oppositeEdge);
+
 		// Check for signal on the same edge
 		SignalBoundary immediateBoundary = startEdge.getEdgeData()
 			.next(EdgePointType.SIGNAL, node1, node2, startEdge, signal.getLocationOn(node1, node2, startEdge));
 		if (immediateBoundary != null) {
 			if (boundaryCallback.test(Pair.of(node1, immediateBoundary)))
-				notifyTrains(graph, startEdge, startEdges.get(!front));
+				notifyTrains(graph, startEdge, oppositeEdge);
 			return;
 		}
 
@@ -134,16 +147,20 @@ public class SignalPropagator {
 
 					// no boundary- update group of edge
 					if (!signalData.hasSignalBoundaries()) {
-						if (nonBoundaryCallback.test(signalData))
-							notifyTrains(graph, currentEdge);
+						if (!nonBoundaryCallback.test(signalData))
+							continue;
+						notifyTrains(graph, currentEdge);
+						Create.RAILWAYS.sync.edgeDataChanged(graph, currentNode, nextNode, edge, oppositeEdge);
 						continue;
 					}
 
 					// other/own boundary found
 					SignalBoundary nextBoundary =
 						signalData.next(EdgePointType.SIGNAL, currentNode, nextNode, currentEdge, 0);
-					if (boundaryCallback.test(Pair.of(currentNode, nextBoundary)))
+					if (boundaryCallback.test(Pair.of(currentNode, nextBoundary))) {
 						notifyTrains(graph, edge, oppositeEdge);
+						Create.RAILWAYS.sync.edgeDataChanged(graph, currentNode, nextNode, edge, oppositeEdge);
+					}
 					continue EdgeWalk;
 				}
 

src/main/java/com/simibubi/create/content/logistics/trains/management/signal/SingleTileEdgePoint.java

@@ -34,15 +34,10 @@ public abstract class SingleTileEdgePoint extends TrackEdgePoint {
 	}
 
 	@Override
-	public final void read(CompoundTag nbt) {
-		read(nbt, false);
-	}
-
 	public void read(CompoundTag nbt, boolean migration) {
+		super.read(nbt, migration);
 		if (migration)
 			return;
-
-		super.read(nbt);
 		tilePos = NbtUtils.readBlockPos(nbt.getCompound("TilePos"));
 	}
 

src/main/java/com/simibubi/create/content/logistics/trains/management/signal/TrackEdgePoint.java

@@ -16,6 +16,7 @@ import net.minecraft.core.BlockPos;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.NbtUtils;
 import net.minecraft.nbt.Tag;
+import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.world.level.LevelAccessor;
 
 public abstract class TrackEdgePoint {
@@ -82,19 +83,35 @@ public abstract class TrackEdgePoint {
 			.equals(node1.getLocation());
 	}
 
-	public void read(CompoundTag nbt) {
+	public void read(CompoundTag nbt, boolean migration) {
+		if (migration)
+			return;
+
 		id = nbt.getUUID("Id");
 		position = nbt.getDouble("Position");
 		edgeLocation = Couple.deserializeEach(nbt.getList("Edge", Tag.TAG_COMPOUND),
 			tag -> TrackNodeLocation.fromPackedPos(NbtUtils.readBlockPos(tag)));
 	}
 
+	public void read(FriendlyByteBuf buffer) {
+		id = buffer.readUUID();
+		edgeLocation = Couple.create(() -> TrackNodeLocation.fromPackedPos(buffer.readBlockPos()));
+		position = buffer.readDouble();
+	}
+
 	public void write(CompoundTag nbt) {
 		nbt.putUUID("Id", id);
 		nbt.putDouble("Position", position);
 		nbt.put("Edge", edgeLocation.serializeEach(loc -> NbtUtils.writeBlockPos(new BlockPos(loc))));
 	}
 
+	public void write(FriendlyByteBuf buffer) {
+		buffer.writeResourceLocation(type.getId());
+		buffer.writeUUID(id);
+		edgeLocation.forEach(loc -> buffer.writeBlockPos(new BlockPos(loc)));
+		buffer.writeDouble(position);
+	}
+
 	public void tick(TrackGraph graph) {}
 
 	protected void removeFromAllGraphs() {

src/main/java/com/simibubi/create/foundation/command/DumpRailwaysCommand.java

@@ -6,7 +6,7 @@ import java.util.UUID;
 import java.util.function.BiConsumer;
 
 import com.mojang.brigadier.builder.ArgumentBuilder;
-import com.simibubi.create.Create;
+import com.simibubi.create.CreateClient;
 import com.simibubi.create.content.logistics.trains.GlobalRailwayManager;
 import com.simibubi.create.content.logistics.trains.TrackGraph;
 import com.simibubi.create.content.logistics.trains.entity.Train;
@@ -40,7 +40,7 @@ public class DumpRailwaysCommand {
 	}
 
 	static void fillReport(ServerLevel level, BiConsumer<String, Integer> chat) {
-		GlobalRailwayManager railways = Create.RAILWAYS;
+		GlobalRailwayManager railways = CreateClient.RAILWAYS;
 		int white = ChatFormatting.WHITE.getColor();
 		int blue = 0xD3DEDC;
 		int darkBlue = 0x92A9BD;
@@ -68,6 +68,8 @@ public class DumpRailwaysCommand {
 				chat.accept(" -> " + signals.size() + " registered Signals", blue);
 			for (GlobalStation globalStation : graph.getPoints(EdgePointType.STATION)) {
 				BlockPos pos = globalStation.getTilePos();
+				if (pos == null)
+					pos = BlockPos.ZERO;
 				chat.accept(" -> " + globalStation.name + " (" + globalStation.id.toString()
 					.substring(0, 5) + ") [" + pos.getX() + "," + pos.getY() + "," + pos.getZ() + "]", darkBlue);
 				if (globalStation.getPresentTrain() != null) {

src/main/java/com/simibubi/create/foundation/networking/AllPackets.java

@@ -43,10 +43,11 @@ import com.simibubi.create.content.logistics.item.filter.FilterScreenPacket;
 import com.simibubi.create.content.logistics.packet.ConfigureStockswitchPacket;
 import com.simibubi.create.content.logistics.packet.FunnelFlapPacket;
 import com.simibubi.create.content.logistics.packet.TunnelFlapPacket;
-import com.simibubi.create.content.logistics.trains.TrackGraphSync.RailGraphSyncPacket;
+import com.simibubi.create.content.logistics.trains.TrackGraphSyncPacket;
 import com.simibubi.create.content.logistics.trains.management.StationEditPacket;
 import com.simibubi.create.content.logistics.trains.management.TrainEditPacket;
 import com.simibubi.create.content.logistics.trains.management.schedule.ScheduleEditPacket;
+import com.simibubi.create.content.logistics.trains.management.signal.SignalEdgeGroupPacket;
 import com.simibubi.create.content.schematics.packet.ConfigureSchematicannonPacket;
 import com.simibubi.create.content.schematics.packet.InstantSchematicPacket;
 import com.simibubi.create.content.schematics.packet.SchematicPlacePacket;
@@ -132,7 +133,8 @@ public enum AllPackets {
 	SOUL_PULSE(SoulPulseEffectPacket.class, SoulPulseEffectPacket::new, PLAY_TO_CLIENT),
 	PERSISTENT_DATA(ISyncPersistentData.PersistentDataPacket.class, ISyncPersistentData.PersistentDataPacket::new, PLAY_TO_CLIENT),
 	SYNC_POTATO_PROJECTILE_TYPES(PotatoProjectileTypeManager.SyncPacket.class, PotatoProjectileTypeManager.SyncPacket::new, PLAY_TO_CLIENT),
-	SYNC_RAIL_GRAPH(RailGraphSyncPacket.class, RailGraphSyncPacket::new, PLAY_TO_CLIENT),
+	SYNC_RAIL_GRAPH(TrackGraphSyncPacket.class, TrackGraphSyncPacket::new, PLAY_TO_CLIENT),
+	SYNC_EDGE_GROUP(SignalEdgeGroupPacket.class, SignalEdgeGroupPacket::new, PLAY_TO_CLIENT),
 	REMOVE_TE(RemoveTileEntityPacket.class, RemoveTileEntityPacket::new, PLAY_TO_CLIENT),
 
 	;