Raise event when entity paused state changes.

FullState was getting updated before ResetPredictedEntities ran instead of after. So ResetPredictedEntities was applying data to stuff like containers that depends on entities that hadn't been made yet.

.github/workflows/test-content.yml

@@ -38,4 +38,4 @@ jobs:
     - name: Content.Tests
       run: dotnet test --no-build Content.Tests/Content.Tests.csproj -v n
     - name: Content.IntegrationTests
-      run: dotnet test --no-build Content.IntegrationTests/Content.IntegrationTests.csproj -v n
+      run: COMPlus_gcServer=1 dotnet test --no-build Content.IntegrationTests/Content.IntegrationTests.csproj -v n

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "ManagedHttpListener"]
 	path = ManagedHttpListener
 	url = https://github.com/space-wizards/ManagedHttpListener.git
+[submodule "Linguini"]
+	path = Linguini
+	url = https://github.com/space-wizards/Linguini

OpenToolkit.GraphicsLibraryFramework/GLFWNative.cs

@@ -23,12 +23,12 @@ namespace OpenToolkit.GraphicsLibraryFramework
                     return IntPtr.Zero;
                 }
 
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+                if (OperatingSystem.IsLinux())
                 {
                     return NativeLibrary.Load("libglfw.so.3", assembly, path);
                 }
 
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+                if (OperatingSystem.IsMacOS())
                 {
                     return NativeLibrary.Load("libglfw.3.dylib", assembly, path);
                 }

Resources/EngineCredits/Libraries.yml

@@ -23,6 +23,48 @@
     OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
     WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+- name: Box2D
+  license:
+    MIT License
+
+    Copyright (c) 2019 Erin Catto
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is 
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+
+- name: Bullet Physics SDK
+  license:
+    The files in this repository are licensed under the zlib license, except for the files under 'Extras' and examples/ThirdPartyLibs.
+
+    Bullet Continuous Collision Detection and Physics Library
+    http://bulletphysics.org
+
+    This software is provided 'as-is', without any express or implied warranty.
+    In no event will the authors be held liable for any damages arising from the use of this software.
+    Permission is granted to anyone to use this software for any purpose,
+    including commercial applications, and to alter it and redistribute it freely,
+    subject to the following restrictions:
+
+    1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. 
+    If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+    2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+    3. This notice may not be removed or altered from any source distribution. 
+
 - name: Castle Core
   license: |
     Copyright 2004-2016 Castle Project - http://www.castleproject.org/
@@ -317,6 +359,43 @@
     See the License for the specific language governing permissions and
     limitations under the License.
 
+- name: Farseer Physics Engine
+  license:
+    Microsoft Permissive License (Ms-PL)
+
+    This license governs use of the accompanying software.
+    If you use the software, you accept this license.
+    If you do not accept the license, do not use the software.
+
+    1. Definitions
+    The terms "reproduce," "reproduction," "derivative works," and "distribution" have the same meaning here as under U.S. copyright law.
+    A "contribution" is the original software, or any additions or changes to the software.
+    A "contributor" is any person that distributes its contribution under this license.
+    "Licensed patents" are a contributor's patent claims that read directly on its contribution.
+
+    2. Grant of Rights
+    (A) Copyright Grant- Subject to the terms of this license, including the license conditions and limitations in section 3, 
+    each contributor grants you a non-exclusive, worldwide, royalty-free copyright license to reproduce its contribution, 
+    prepare derivative works of its contribution, and distribute its contribution or any derivative works that you create.
+    (B) Patent Grant- Subject to the terms of this license, including the license conditions and limitations in section 3, 
+    each contributor grants you a non-exclusive, worldwide, royalty-free license under its licensed patents to 
+    make, have made, use, sell, offer for sale, import, and/or otherwise dispose of its contribution in the software or 
+    derivative works of the contribution in the software.
+
+    3. Conditions and Limitations
+    (A) No Trademark License- This license does not grant you rights to use any contributors' name, logo, or trademarks.
+    (B) If you bring a patent claim against any contributor over patents that you claim are infringed by the software, 
+    your patent license from such contributor to the software ends automatically.
+    (C) If you distribute any portion of the software, you must retain all copyright, patent, trademark, 
+    and attribution notices that are present in the software.
+    (D) If you distribute any portion of the software in source code form, you may do so only under this license by 
+    including a complete copy of this license with your distribution. If you distribute any portion of the software in 
+    compiled or object code form, you may only do so under a license that complies with this license.
+    (E) The software is licensed "as-is." You bear the risk of using it. The contributors give no express warranties, 
+    guarantees or conditions. You may have additional consumer rights under your local laws which this license cannot change. 
+    To the extent permitted under your local laws, the contributors exclude the implied warranties of 
+    merchantability, fitness for a particular purpose and non-infringement.
+
 - name: Mono.Cecil
   license: |
     Copyright (c) 2008 - 2015 Jb Evain

Resources/Locale/en-US/console.ftl

@@ -1 +0,0 @@
-console-line-edit-placeholder = Command Here

Resources/Locale/en-US/custom-controls.ftl

@@ -0,0 +1,7 @@
+## EntitySpawnWindow
+
+entity-spawn-window-title = Entity Spawn Panel
+entity-spawn-window-search-bar-placeholder = search
+entity-spawn-window-clear-button = Clear
+entity-spawn-window-erase-button-text = Erase Mode
+entity-spawn-window-override-menu-tooltip = Override placement

Resources/Locale/en-US/tab-container.ftl

@@ -0,0 +1 @@
+tab-container-not-tab-title-provided = No title

Resources/Locale/en-US/view-variables.ftl

@@ -0,0 +1,11 @@
+## ViewVariablesInstanceEntity
+
+view-variable-instance-entity-server-components-add-component-button-placeholder = Add Component
+view-variable-instance-entity-client-variables-tab-title = Client Variables
+view-variable-instance-entity-client-components-tab-title = Client Components
+view-variable-instance-entity-server-variables-tab-title = Server Variables
+view-variable-instance-entity-server-components-tab-title = Server Components
+view-variable-instance-entity-client-components-search-bar-placeholder = Search
+view-variable-instance-entity-server-components-search-bar-placeholder = Search
+view-variable-instance-entity-add-window-server-components = Add Component [S]
+view-variable-instance-entity-add-window-client-components = Add Component [C]

Robust.Client.NameGenerator/XamlUiPartialClassGenerator.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Text;
 using Microsoft.CodeAnalysis;
@@ -147,9 +148,10 @@ namespace {nameSpace}
             foreach (var typeSymbol in symbols)
             {
                 var xamlFileName = $"{typeSymbol.Name}.xaml";
-                var relevantXamlFile = context.AdditionalFiles.FirstOrDefault(t => t.Path.EndsWith(xamlFileName));
+                var xamlFileNameSep = $"{Path.DirectorySeparatorChar}{xamlFileName}";
+                var relevantXamlFiles = context.AdditionalFiles.Where(t => t.Path.EndsWith(xamlFileNameSep)).ToArray();
 
-                if (relevantXamlFile == null)
+                if (relevantXamlFiles.Length == 0)
                 {
                     context.ReportDiagnostic(
                         Diagnostic.Create(
@@ -165,13 +167,28 @@ namespace {nameSpace}
                     continue;
                 }
 
-                var txt = relevantXamlFile.GetText()?.ToString();
-                if (txt == null)
+                if (relevantXamlFiles.Length > 1)
                 {
                     context.ReportDiagnostic(
                         Diagnostic.Create(
                             new DiagnosticDescriptor(
                                 "RXN0002",
+                                $"Found multiple candidate XAML files for {typeSymbol}",
+                                $"Multiple files exist with name {xamlFileName}",
+                                "Usage",
+                                DiagnosticSeverity.Error,
+                                true),
+                            typeSymbol.Locations[0]));
+                    continue;
+                }
+
+                var txt = relevantXamlFiles[0].GetText()?.ToString();
+                if (txt == null)
+                {
+                    context.ReportDiagnostic(
+                        Diagnostic.Create(
+                            new DiagnosticDescriptor(
+                                "RXN0004",
                                 $"Unexpected empty Xaml-File was found at {xamlFileName}",
                                 "Expected Content due to a Class with the same name being annotated with [GenerateTypedNameReferences].",
                                 "Usage",
@@ -192,7 +209,7 @@ namespace {nameSpace}
                     context.ReportDiagnostic(
                         Diagnostic.Create(
                             new DiagnosticDescriptor(
-                                "AXN0003",
+                                "RXN0003",
                                 "Unhandled exception occured while generating typed Name references.",
                                 $"Unhandled exception occured while generating typed Name references: {e}",
                                 "Usage",

Robust.Client/Audio/Midi/MidiManager.cs

@@ -225,7 +225,7 @@ namespace Robust.Client.Audio.Midi
                 // Since the last loaded soundfont takes priority, we load the fallback soundfont before the soundfont.
                 renderer.LoadSoundfont(FallbackSoundfont);
 
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+                if (OperatingSystem.IsLinux())
                 {
                     foreach (var filepath in LinuxSoundfonts)
                     {
@@ -243,12 +243,12 @@ namespace Robust.Client.Audio.Midi
                         break;
                     }
                 }
-                else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+                else if (OperatingSystem.IsMacOS())
                 {
                     if (File.Exists(OsxSoundfont) && SoundFont.IsSoundFont(OsxSoundfont))
                         renderer.LoadSoundfont(OsxSoundfont, true);
                 }
-                else if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                else if (OperatingSystem.IsWindows())
                 {
                     if (File.Exists(WindowsSoundfont) && SoundFont.IsSoundFont(WindowsSoundfont))
                         renderer.LoadSoundfont(WindowsSoundfont, true);

Robust.Client/Audio/Midi/MidiRenderer.cs

@@ -628,10 +628,15 @@ namespace Robust.Client.Audio.Midi
         void IMidiRenderer.InternalDispose()
         {
             Source?.Dispose();
+            _driver?.Dispose();
+
+            // Do NOT dispose of the sequencer after the synth or it'll cause a segfault for some fucking reason.
+            _sequencer?.UnregisterClient(_debugRegister);
+            _sequencer?.UnregisterClient(_synthRegister);
+            _sequencer?.Dispose();
+            
             _synth?.Dispose();
             _player?.Dispose();
-            _driver?.Dispose();
-            _sequencer?.Dispose();
         }
     }
 }

Robust.Client/Console/Commands/LightBBCommand.cs

@@ -0,0 +1,19 @@
+#if DEBUG
+using Robust.Client.GameObjects;
+using Robust.Shared.Console;
+using Robust.Shared.GameObjects;
+
+namespace Robust.Client.Console.Commands
+{
+    internal sealed class LightDebugCommand : IConsoleCommand
+    {
+        public string Command => "lightbb";
+        public string Description => "Toggles whether to show light bounding boxes";
+        public string Help => $"{Command}";
+        public void Execute(IConsoleShell shell, string argStr, string[] args)
+        {
+            EntitySystem.Get<DebugLightTreeSystem>().Enabled ^= true;
+        }
+    }
+}
+#endif

Robust.Client/Console/Commands/Scripting.cs

@@ -1,6 +1,5 @@
 using Robust.Shared.Console;
 using Robust.Shared.IoC;
-using Robust.Shared.Localization;
 
 namespace Robust.Client.Console.Commands
 {
@@ -41,7 +40,7 @@ namespace Robust.Client.Console.Commands
             var mgr = IoCManager.Resolve<IScriptClient>();
             if (!mgr.CanScript)
             {
-                shell.WriteError(Loc.GetString("You do not have server side scripting permission."));
+                shell.WriteError("You do not have server side scripting permission.");
                 return;
             }
 

Robust.Client/Console/ScriptConsoleClient.cs

@@ -1,5 +1,4 @@
 #if CLIENT_SCRIPTING
-using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
@@ -14,7 +13,6 @@ using Microsoft.CodeAnalysis.Text;
 using Robust.Client.UserInterface.CustomControls;
 using Robust.Client.ViewVariables;
 using Robust.Shared.IoC;
-using Robust.Shared.Localization;
 using Robust.Shared.Maths;
 using Robust.Shared.Reflection;
 using Robust.Shared.Scripting;
@@ -43,14 +41,14 @@ namespace Robust.Client.Console
 
         public ScriptConsoleClient()
         {
-            Title = Loc.GetString("Robust C# Interactive (CLIENT)");
+            Title = "Robust C# Interactive (CLIENT)";
             ScriptInstanceShared.InitDummy();
 
             _globals = new ScriptGlobalsImpl(this);
 
             IoCManager.InjectDependencies(this);
 
-            OutputPanel.AddText(Loc.GetString(@"Robust C# interactive console (CLIENT)."));
+            OutputPanel.AddText("Robust C# interactive console (CLIENT).");
             OutputPanel.AddText(">");
         }
 

Robust.Client/Console/WatchWindow.cs

@@ -8,8 +8,6 @@ using Robust.Client.UserInterface;
 using Robust.Client.UserInterface.Controls;
 using Robust.Client.UserInterface.CustomControls;
 using Robust.Shared.IoC;
-using Robust.Shared.Localization;
-using Robust.Shared.Maths;
 using Robust.Shared.Reflection;
 using Robust.Shared.Scripting;
 using Robust.Shared.Timing;
@@ -31,7 +29,7 @@ namespace Robust.Client.Console
 
             ScriptInstanceShared.InitDummy();
 
-            Title = Loc.GetString("Watch Window");
+            Title = "Watch Window";
 
             var mainVBox = new VBoxContainer
             {
@@ -49,11 +47,11 @@ namespace Robust.Client.Console
                             (_addWatchEdit = new HistoryLineEdit
                             {
                                 HorizontalExpand = true,
-                                PlaceHolder = Loc.GetString("Add watch (C# interactive)")
+                                PlaceHolder = "Add watch (C# interactive)"
                             }),
                             (_addWatchButton = new Button
                             {
-                                Text = Loc.GetString("Add")
+                                Text = "Add"
                             })
                         }
                     }
@@ -118,7 +116,7 @@ namespace Robust.Client.Console
                         }),
                         (delButton = new Button
                         {
-                            Text = Loc.GetString("Remove")
+                            Text = "Remove"
                         }),
                     }
                 });
@@ -178,7 +176,7 @@ namespace Robust.Client.Console
                             ClipText = true,
                             HorizontalExpand = true
                         },
-                        (delButton = new Button {Text = Loc.GetString("Remove")})
+                        (delButton = new Button {Text = "Remove"})
                     }
                 });
 

Robust.Client/Debugging/DebugDrawing.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using Robust.Client.Graphics;
 using Robust.Client.Input;
@@ -130,17 +130,17 @@ namespace Robust.Client.Debugging
                 {
                     if (body != _hoverBodies[0])
                     {
-                        DrawString(screenHandle, _font, drawPos + new Vector2(0, row * lineHeight), "------");
+                        screenHandle.DrawString(_font, drawPos + new Vector2(0, row * lineHeight), "------");
                         row++;
                     }
 
-                    DrawString(screenHandle, _font, drawPos + new Vector2(0, row * lineHeight), $"Ent: {body.Owner}");
+                    screenHandle.DrawString(_font, drawPos + new Vector2(0, row * lineHeight), $"Ent: {body.Owner}");
                     row++;
-                    DrawString(screenHandle, _font, drawPos + new Vector2(0, row * lineHeight), $"Layer: {Convert.ToString(body.CollisionLayer, 2)}");
+                    screenHandle.DrawString(_font, drawPos + new Vector2(0, row * lineHeight), $"Layer: {Convert.ToString(body.CollisionLayer, 2)}");
                     row++;
-                    DrawString(screenHandle, _font, drawPos + new Vector2(0, row * lineHeight), $"Mask: {Convert.ToString(body.CollisionMask, 2)}");
+                    screenHandle.DrawString(_font, drawPos + new Vector2(0, row * lineHeight), $"Mask: {Convert.ToString(body.CollisionMask, 2)}");
                     row++;
-                    DrawString(screenHandle, _font, drawPos + new Vector2(0, row * lineHeight), $"Enabled: {body.CanCollide}, Hard: {body.Hard}, Anchored: {(body).BodyType == BodyType.Static}");
+                    screenHandle.DrawString(_font, drawPos + new Vector2(0, row * lineHeight), $"Enabled: {body.CanCollide}, Hard: {body.Hard}, Anchored: {(body).BodyType == BodyType.Static}");
                     row++;
                 }
 
@@ -199,17 +199,6 @@ namespace Robust.Client.Debugging
                 }
             }
 
-            private static void DrawString(DrawingHandleScreen handle, Font font, Vector2 pos, string str)
-            {
-                var baseLine = new Vector2(pos.X, font.GetAscent(1) + pos.Y);
-
-                foreach (var rune in str.EnumerateRunes())
-                {
-                    var advance = font.DrawChar(handle, rune, baseLine, 1, Color.White);
-                    baseLine += new Vector2(advance, 0);
-                }
-            }
-
             private class PhysDrawingAdapter : DebugDrawingHandle
             {
                 private readonly DrawingHandleWorld _handle;

Robust.Client/GameController/GameController.cs

@@ -82,7 +82,7 @@ namespace Robust.Client
             _commandLineArgs = args;
         }
 
-        private bool StartupContinue(DisplayMode displayMode)
+        internal bool StartupContinue(DisplayMode displayMode)
         {
             _clyde.InitializePostWindowing();
             _clyde.SetWindowTitle(Options.DefaultWindowTitle);
@@ -196,7 +196,7 @@ namespace Robust.Client
             return true;
         }
 
-        private bool StartupSystemSplash(Func<ILogHandler>? logHandlerFactory)
+        internal bool StartupSystemSplash(Func<ILogHandler>? logHandlerFactory)
         {
             ReadInitialLaunchState();
 
@@ -222,6 +222,8 @@ namespace Robust.Client
                 }
             }
 
+            ProgramShared.PrintRuntimeInfo(_logManager.RootSawmill);
+
             // Figure out user data directory.
             var userDataDir = GetUserDataDir();
 
@@ -469,7 +471,7 @@ namespace Robust.Client
             Clyde,
         }
 
-        private void Cleanup()
+        internal void Cleanup()
         {
             _networkManager.Shutdown("Client shutting down");
             _midiManager.Shutdown();

Robust.Client/GameObjects/ClientEntityManager.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using Prometheus;
 using Robust.Client.GameStates;
+using Robust.Client.Player;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Network;
@@ -16,6 +17,7 @@ namespace Robust.Client.GameObjects
     /// </summary>
     public sealed class ClientEntityManager : EntityManager, IClientEntityManagerInternal
     {
+        [Dependency] private readonly IPlayerManager _playerManager = default!;
         [Dependency] private readonly IClientNetManager _networkManager = default!;
         [Dependency] private readonly IClientGameStateManager _gameStateManager = default!;
         [Dependency] private readonly IGameTiming _gameTiming = default!;
@@ -143,7 +145,11 @@ namespace Robust.Client.GameObjects
                     return;
 
                 case EntityMessageType.SystemMessage:
-                    ReceivedSystemMessage?.Invoke(this, message.SystemMessage);
+                    var msg = message.SystemMessage;
+                    var sessionType = typeof(EntitySessionMessage<>).MakeGenericType(msg.GetType());
+                    var sessionMsg = Activator.CreateInstance(sessionType, new EntitySessionEventArgs(_playerManager.LocalPlayer!.Session), msg)!;
+                    ReceivedSystemMessage?.Invoke(this, msg);
+                    ReceivedSystemMessage?.Invoke(this, sessionMsg);
                     return;
             }
         }

Robust.Client/GameObjects/Components/Appearance/AppearanceComponent.cs

@@ -104,7 +104,7 @@ namespace Robust.Client.GameObjects
             _appearanceDirty = false;
         }
 
-        public override void Initialize()
+        protected override void Initialize()
         {
             base.Initialize();
 

Robust.Client/GameObjects/Components/Eye/EyeComponent.cs

@@ -116,7 +116,7 @@ namespace Robust.Client.GameObjects
         public MapCoordinates? Position => _eye?.Position;
 
         /// <inheritdoc />
-        public override void Initialize()
+        protected override void Initialize()
         {
             base.Initialize();
 
@@ -156,7 +156,7 @@ namespace Robust.Client.GameObjects
             VisibilityMask = state.VisibilityMask;
         }
 
-        public override void OnRemove()
+        protected override void OnRemove()
         {
             base.OnRemove();
 

Robust.Client/GameObjects/Components/Light/ClientOccluderComponent.cs

@@ -34,11 +34,11 @@ namespace Robust.Client.GameObjects
 
             if (Owner.Transform.Anchored)
             {
-                SnapGridOnPositionChanged();
+                AnchorStateChanged();
             }
         }
 
-        public void SnapGridOnPositionChanged()
+        public void AnchorStateChanged()
         {
             SendDirty();
 

Robust.Client/GameObjects/Components/Light/PointLightComponent.cs

@@ -1,10 +1,12 @@
-using System;
+using System;
 using System.Collections.Generic;
 using Robust.Client.Graphics;
 using Robust.Client.ResourceManagement;
 using Robust.Shared.Animations;
+using Robust.Shared.Configuration;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
+using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Serialization;
@@ -44,11 +46,29 @@ namespace Robust.Client.GameObjects
         public bool Enabled
         {
             get => _enabled;
-            set => _enabled = value;
+            set
+            {
+                if (_enabled == value) return;
+
+                _enabled = value;
+                Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new PointLightUpdateEvent());
+            }
         }
 
         [ViewVariables(VVAccess.ReadWrite)]
-        public bool ContainerOccluded { get; set; }
+        public bool ContainerOccluded
+        {
+            get => _containerOccluded;
+            set
+            {
+                if (_containerOccluded == value) return;
+
+                _containerOccluded = value;
+                Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new PointLightUpdateEvent());
+            }
+        }
+
+        private bool _containerOccluded;
 
         /// <summary>
         ///     Determines if the light mask should automatically rotate with the entity. (like a flashlight)
@@ -117,30 +137,13 @@ namespace Robust.Client.GameObjects
         public bool VisibleNested
         {
             get => _visibleNested;
-            set
-            {
-                if (_visibleNested == value) return;
-                _visibleNested = value;
-                if (value)
-                {
-                    if (Owner.Transform.Parent == null) return;
-
-                    _lightOnParent = true;
-                }
-                else
-                {
-                    if (!_lightOnParent) return;
-
-                    _lightOnParent = false;
-                }
-            }
+            set => _visibleNested = value;
         }
 
         [DataField("radius")]
         private float _radius = 5f;
         [DataField("nestedvisible")]
         private bool _visibleNested = true;
-        private bool _lightOnParent;
         [DataField("color")]
         private Color _color = Color.White;
         [DataField("offset")]
@@ -167,6 +170,8 @@ namespace Robust.Client.GameObjects
             get => _radius;
             set
             {
+                if (MathHelper.CloseTo(value, _radius)) return;
+
                 _radius = MathF.Max(value, 0.01f); // setting radius to 0 causes exceptions, so just use a value close enough to zero that it's unnoticeable.
                 Owner.EntityManager.EventBus.RaiseEvent(EventSource.Local, new PointLightRadiusChangedEvent(this));
             }
@@ -180,17 +185,8 @@ namespace Robust.Client.GameObjects
                 Mask = null;
         }
 
-        /// <summary>
-        /// What MapId we are intersecting for RenderingTreeSystem.
-        /// </summary>
         [ViewVariables]
-        internal MapId IntersectingMapId { get; set; } = MapId.Nullspace;
-
-        /// <summary>
-        /// What grids we're on for RenderingTreeSystem.
-        /// </summary>
-        [ViewVariables]
-        internal List<GridId> IntersectingGrids = new();
+        internal RenderingTreeComponent? RenderTree { get; set; }
 
         void ISerializationHooks.AfterDeserialization()
         {
@@ -200,42 +196,13 @@ namespace Robust.Client.GameObjects
             }
         }
 
-        public override void Initialize()
+        protected override void Initialize()
         {
             base.Initialize();
             UpdateMask();
         }
 
-        /// <inheritdoc />
-        public override void HandleMessage(ComponentMessage message, IComponent? component)
-        {
-            base.HandleMessage(message, component);
-
-            if (message is ParentChangedMessage msg)
-            {
-                HandleTransformParentChanged(msg);
-            }
-        }
-
-        private void HandleTransformParentChanged(ParentChangedMessage obj)
-        {
-            // TODO: this does not work for things nested multiply layers deep.
-            if (!VisibleNested)
-            {
-                return;
-            }
-
-            if (obj.NewParent != null && obj.NewParent.IsValid())
-            {
-                _lightOnParent = true;
-            }
-            else
-            {
-                _lightOnParent = false;
-            }
-        }
-
-        public override void OnRemove()
+        protected override void OnRemove()
         {
             base.OnRemove();
 
@@ -270,4 +237,9 @@ namespace Robust.Client.GameObjects
             PointLightComponent = pointLightComponent;
         }
     }
+
+    internal sealed class PointLightUpdateEvent : EntityEventArgs
+    {
+
+    }
 }

Robust.Client/GameObjects/Components/Renderable/SpriteComponent.cs

@@ -42,7 +42,13 @@ namespace Robust.Client.GameObjects
         public override bool Visible
         {
             get => _visible;
-            set => _visible = value;
+            set
+            {
+                if (_visible == value) return;
+                _visible = value;
+
+                Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new SpriteUpdateEvent());
+            }
         }
 
         [DataField("drawdepth", customTypeSerializer: typeof(ConstantSerializer<DrawDepthTag>))]
@@ -125,17 +131,8 @@ namespace Robust.Client.GameObjects
         [DataField("directional")]
         private bool _directional = true;
 
-        /// <summary>
-        /// What MapId we are intersecting for RenderingTreeSystem.
-        /// </summary>
         [ViewVariables]
-        internal MapId IntersectingMapId { get; set; } = MapId.Nullspace;
-
-        /// <summary>
-        /// What grids we're on for RenderingTreeSystem.
-        /// </summary>
-        [ViewVariables]
-        internal List<GridId> IntersectingGrids { get; } = new();
+        internal RenderingTreeComponent? RenderTree { get; set; } = null;
 
         [DataField("layerDatums")]
         private List<PrototypeLayerData> LayerDatums
@@ -152,7 +149,7 @@ namespace Robust.Client.GameObjects
             }
             set
             {
-                if(value == null) return;
+                if (value == null) return;
 
                 Layers.Clear();
                 foreach (var layerDatum in value)
@@ -162,11 +159,12 @@ namespace Robust.Client.GameObjects
                     if (!string.IsNullOrWhiteSpace(layerDatum.RsiPath))
                     {
                         var path = TextureRoot / layerDatum.RsiPath;
-                        try
+
+                        if (IoCManager.Resolve<IResourceCache>().TryGetResource(path, out RSIResource? resource))
                         {
-                            layer.RSI = IoCManager.Resolve<IResourceCache>().GetResource<RSIResource>(path).RSI;
+                            layer.RSI = resource.RSI;
                         }
-                        catch
+                        else
                         {
                             Logger.ErrorS(LogCategory, "Unable to load layer RSI '{0}'.", path);
                         }
@@ -265,7 +263,7 @@ namespace Robust.Client.GameObjects
                 }
 
                 _layerMapShared = true;
-                UpdateIsInert();
+                QueueUpdateIsInert();
             }
         }
 
@@ -308,17 +306,30 @@ namespace Robust.Client.GameObjects
         }
 
         [DataField("sprite", readOnly: true)] private string? rsi;
-        [DataField("layers", readOnly: true)] private List<PrototypeLayerData> layerDatums = new ();
+        [DataField("layers", readOnly: true)] private List<PrototypeLayerData> layerDatums = new();
 
         [DataField("state", readOnly: true)] private string? state;
         [DataField("texture", readOnly: true)] private string? texture;
 
         [ViewVariables(VVAccess.ReadWrite)]
-        public bool ContainerOccluded { get; set; }
+        public bool ContainerOccluded
+        {
+            get => _containerOccluded;
+            set
+            {
+                if (_containerOccluded == value) return;
+                _containerOccluded = value;
+                Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new SpriteUpdateEvent());
+            }
+        }
+
+        private bool _containerOccluded;
 
         [ViewVariables(VVAccess.ReadWrite)]
         public bool TreeUpdateQueued { get; set; }
 
+        [ViewVariables(VVAccess.ReadWrite)] private bool _inertUpdateQueued;
+
         [ViewVariables(VVAccess.ReadWrite)]
         public ShaderInstance? PostShader { get; set; }
 
@@ -348,13 +359,13 @@ namespace Robust.Client.GameObjects
                 if (!string.IsNullOrWhiteSpace(rsi))
                 {
                     var rsiPath = TextureRoot / rsi;
-                    try
+                    if(IoCManager.Resolve<IResourceCache>().TryGetResource(rsiPath, out RSIResource? resource))
                     {
-                        BaseRSI = IoCManager.Resolve<IResourceCache>().GetResource<RSIResource>(rsiPath).RSI;
+                        BaseRSI = resource.RSI;
                     }
-                    catch (Exception e)
+                    else
                     {
-                        Logger.ErrorS(SpriteComponent.LogCategory, "Unable to load RSI '{0}'. Trace:\n{1}", rsiPath, e);
+                        Logger.ErrorS(LogCategory, "Unable to load RSI '{0}'. Trace:\n{1}", rsiPath);
                     }
                 }
             }
@@ -482,7 +493,7 @@ namespace Robust.Client.GameObjects
 
         public int AddBlankLayer(int? newIndex = null)
         {
-            var layer = new Layer(this) {Visible = false};
+            var layer = new Layer(this) { Visible = false };
             return AddLayer(layer, newIndex);
         }
 
@@ -511,13 +522,13 @@ namespace Robust.Client.GameObjects
 
         public int AddLayer(Texture? texture, int? newIndex = null)
         {
-            var layer = new Layer(this) {Texture = texture};
+            var layer = new Layer(this) { Texture = texture };
             return AddLayer(layer, newIndex);
         }
 
         public int AddLayer(RSI.StateId stateId, int? newIndex = null)
         {
-            var layer = new Layer(this) {State = stateId};
+            var layer = new Layer(this) { State = stateId };
             if (BaseRSI != null && BaseRSI.TryGetState(stateId, out var state))
             {
                 layer.AnimationTimeLeft = state.GetDelay(0);
@@ -563,7 +574,7 @@ namespace Robust.Client.GameObjects
 
         public int AddLayer(RSI.StateId stateId, RSI? rsi, int? newIndex = null)
         {
-            var layer = new Layer(this) {State = stateId, RSI = rsi};
+            var layer = new Layer(this) { State = stateId, RSI = rsi };
             if (rsi != null && rsi.TryGetState(stateId, out var state))
             {
                 layer.AnimationTimeLeft = state.GetDelay(0);
@@ -619,7 +630,7 @@ namespace Robust.Client.GameObjects
                 index = Layers.Count - 1;
             }
 
-            UpdateIsInert();
+            QueueUpdateIsInert();
             return index;
         }
 
@@ -646,7 +657,7 @@ namespace Robust.Client.GameObjects
                 }
             }
 
-            UpdateIsInert();
+            QueueUpdateIsInert();
         }
 
         public void RemoveLayer(object layerKey)
@@ -1288,8 +1299,8 @@ namespace Robust.Client.GameObjects
 
             var layerColor = color * layer.Color;
 
-            var position = -(Vector2) texture.Size / (2f * EyeManager.PixelsPerMeter) + layer.Offset;
-            var textureSize = texture.Size / (float) EyeManager.PixelsPerMeter;
+            var position = -(Vector2)texture.Size / (2f * EyeManager.PixelsPerMeter) + layer.Offset;
+            var textureSize = texture.Size / (float)EyeManager.PixelsPerMeter;
             var quad = Box2.FromDimensions(position, textureSize);
 
             // TODO: Implement layer-specific rotation and scale.
@@ -1309,7 +1320,7 @@ namespace Robust.Client.GameObjects
         public static Angle CalcRectWorldAngle(Angle worldAngle, int numDirections)
         {
             var theta = worldAngle.Theta;
-            var segSize = (MathF.PI*2) / (numDirections * 2);
+            var segSize = (MathF.PI * 2) / (numDirections * 2);
             var segments = (int)(theta / segSize);
             var odd = segments % 2;
             var result = theta - (segments * segSize) - (odd * segSize);
@@ -1409,7 +1420,7 @@ namespace Robust.Client.GameObjects
             if (curState == null)
                 return;
 
-            var thestate = (SpriteComponentState) curState;
+            var thestate = (SpriteComponentState)curState;
 
             Visible = thestate.Visible;
             DrawDepth = thestate.DrawDepth;
@@ -1497,8 +1508,20 @@ namespace Robust.Client.GameObjects
             };
         }
 
-        private void UpdateIsInert()
+        private void QueueUpdateIsInert()
         {
+            if (_inertUpdateQueued)
+                return;
+
+            _inertUpdateQueued = true;
+            // Yes that null check is valid because of that stupid fucking dummy IEntity.
+            // Who thought that was a good idea.
+            Owner?.EntityManager?.EventBus?.RaiseEvent(EventSource.Local, new SpriteUpdateInertEvent {Sprite = this});
+        }
+
+        internal void DoUpdateIsInert()
+        {
+            _inertUpdateQueued = false;
             IsInert = true;
 
             foreach (var layer in Layers)
@@ -1848,14 +1871,14 @@ namespace Robust.Client.GameObjects
             {
                 AutoAnimated = value;
 
-                _parent.UpdateIsInert();
+                _parent.QueueUpdateIsInert();
             }
 
             public void SetVisible(bool value)
             {
                 Visible = value;
 
-                _parent.UpdateIsInert();
+                _parent.QueueUpdateIsInert();
             }
 
             public void SetRsi(RSI? rsi)
@@ -1887,7 +1910,7 @@ namespace Robust.Client.GameObjects
                     }
                 }
 
-                _parent.UpdateIsInert();
+                _parent.QueueUpdateIsInert();
             }
 
             public void SetState(RSI.StateId stateId)
@@ -1919,7 +1942,7 @@ namespace Robust.Client.GameObjects
                 AnimationTime = 0;
                 AnimationTimeLeft = state.GetDelay(0);
 
-                _parent.UpdateIsInert();
+                _parent.QueueUpdateIsInert();
             }
 
             public void SetTexture(Texture? texture)
@@ -1927,7 +1950,7 @@ namespace Robust.Client.GameObjects
                 State = default;
                 Texture = texture;
 
-                _parent.UpdateIsInert();
+                _parent.QueueUpdateIsInert();
             }
 
             public void SetOffset(Vector2 offset)
@@ -1979,13 +2002,13 @@ namespace Robust.Client.GameObjects
             switch (layerProp)
             {
                 case "texture":
-                    LayerSetTexture(index, (string) value);
+                    LayerSetTexture(index, (string)value);
                     return;
                 case "state":
-                    LayerSetState(index, (string) value);
+                    LayerSetState(index, (string)value);
                     return;
                 case "color":
-                    LayerSetColor(index, (Color) value);
+                    LayerSetColor(index, (Color)value);
                     return;
                 default:
                     throw new ArgumentException($"Unknown layer property '{layerProp}'");
@@ -2030,7 +2053,7 @@ namespace Robust.Client.GameObjects
                 yield break;
             }
 
-            var dummy = new DummyIconEntity {Prototype = prototype};
+            var dummy = new DummyIconEntity { Prototype = prototype };
             var spriteComponent = dummy.AddComponent<SpriteComponent>();
 
             if (prototype.Components.TryGetValue("Appearance", out _))
@@ -2074,7 +2097,7 @@ namespace Robust.Client.GameObjects
                 return GetFallbackState(resourceCache);
             }
 
-            var dummy = new DummyIconEntity {Prototype = prototype};
+            var dummy = new DummyIconEntity { Prototype = prototype };
             var spriteComponent = dummy.AddComponent<SpriteComponent>();
             dummy.Delete();
 
@@ -2111,7 +2134,7 @@ namespace Robust.Client.GameObjects
             {
                 var typeFactory = IoCManager.Resolve<IDynamicTypeFactoryInternal>();
                 var serializationManager = IoCManager.Resolve<ISerializationManager>();
-                var comp = (T) typeFactory.CreateInstanceUnchecked(typeof(T));
+                var comp = (T)typeFactory.CreateInstanceUnchecked(typeof(T));
                 _components[typeof(T)] = comp;
                 comp.Owner = this;
 
@@ -2145,7 +2168,7 @@ namespace Robust.Client.GameObjects
 
             public T GetComponent<T>()
             {
-                return (T) _components[typeof(T)];
+                return (T)_components[typeof(T)];
             }
 
             public IComponent GetComponent(Type type)
@@ -2157,7 +2180,7 @@ namespace Robust.Client.GameObjects
             {
                 component = null;
                 if (!_components.TryGetValue(typeof(T), out var value)) return false;
-                component = (T) value;
+                component = (T)value;
                 return true;
             }
 
@@ -2213,4 +2236,14 @@ namespace Robust.Client.GameObjects
         }
         #endregion
     }
+
+    internal sealed class SpriteUpdateEvent : EntityEventArgs
+    {
+
+    }
+
+    internal struct SpriteUpdateInertEvent
+    {
+        public SpriteComponent Sprite;
+    }
 }

Robust.Client/GameObjects/Components/RenderingTreeComponent.cs

@@ -0,0 +1,43 @@
+using Robust.Shared.GameObjects;
+using Robust.Shared.Maths;
+using Robust.Shared.Physics;
+
+namespace Robust.Client.GameObjects
+{
+    [RegisterComponent]
+    public sealed class RenderingTreeComponent : Component
+    {
+        public override string Name => "RenderingTree";
+
+        internal DynamicTree<SpriteComponent> SpriteTree { get; private set; } = new(SpriteAabbFunc);
+        internal DynamicTree<PointLightComponent> LightTree { get; private set; } = new(LightAabbFunc);
+
+        private static Box2 SpriteAabbFunc(in SpriteComponent value)
+        {
+            var worldPos = value.Owner.Transform.WorldPosition;
+            return new Box2(worldPos, worldPos);
+        }
+
+        private static Box2 LightAabbFunc(in PointLightComponent value)
+        {
+            var worldPos = value.Owner.Transform.WorldPosition;
+
+            var boxSize = value.Radius * 2;
+            return Box2.CenteredAround(worldPos, (boxSize, boxSize));
+        }
+
+        internal static Box2 SpriteAabbFunc(SpriteComponent value, Vector2? worldPos = null)
+        {
+            worldPos ??= value.Owner.Transform.WorldPosition;
+
+            return new Box2(worldPos.Value, worldPos.Value);
+        }
+
+        internal static Box2 LightAabbFunc(PointLightComponent value, Vector2? worldPos = null)
+        {
+            worldPos ??= value.Owner.Transform.WorldPosition;
+            var boxSize = value.Radius * 2;
+            return Box2.CenteredAround(worldPos.Value, (boxSize, boxSize));
+        }
+    }
+}

Robust.Client/GameObjects/EntitySystems/ClientOccluderSystem.cs

@@ -35,7 +35,7 @@ namespace Robust.Client.GameObjects
 
             SubscribeLocalEvent<OccluderDirtyEvent>(HandleDirtyEvent);
 
-            SubscribeLocalEvent<ClientOccluderComponent, SnapGridPositionChangedEvent>(HandleSnapGridMove);
+            SubscribeLocalEvent<ClientOccluderComponent, AnchorStateChangedEvent>(HandleAnchorChanged);
         }
 
         public override void FrameUpdate(float frameTime)
@@ -62,9 +62,9 @@ namespace Robust.Client.GameObjects
             }
         }
 
-        private static void HandleSnapGridMove(EntityUid uid, ClientOccluderComponent component, SnapGridPositionChangedEvent args)
+        private static void HandleAnchorChanged(EntityUid uid, ClientOccluderComponent component, AnchorStateChangedEvent args)
         {
-            component.SnapGridOnPositionChanged();
+            component.AnchorStateChanged();
         }
 
         private void HandleDirtyEvent(OccluderDirtyEvent ev)

Robust.Client/GameObjects/EntitySystems/DebugLightTreeSystem.cs

@@ -0,0 +1,84 @@
+#if DEBUG
+using Robust.Client.Graphics;
+using Robust.Shared.Enums;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+
+namespace Robust.Client.GameObjects
+{
+    internal sealed class DebugLightTreeSystem : EntitySystem
+    {
+        private DebugLightOverlay? _lightOverlay;
+
+        public bool Enabled
+        {
+            get => _enabled;
+            set
+            {
+                if (_enabled == value) return;
+
+                _enabled = value;
+                var overlayManager = IoCManager.Resolve<IOverlayManager>();
+
+                if (_enabled)
+                {
+                    _lightOverlay = new DebugLightOverlay(
+                        IoCManager.Resolve<IEntityLookup>(),
+                        IoCManager.Resolve<IEyeManager>(),
+                        IoCManager.Resolve<IMapManager>(),
+                        Get<RenderingTreeSystem>());
+
+                    overlayManager.AddOverlay(_lightOverlay);
+                }
+                else
+                {
+                    overlayManager.RemoveOverlay(_lightOverlay!);
+                    _lightOverlay = null;
+                }
+            }
+        }
+
+        private bool _enabled;
+
+        private sealed class DebugLightOverlay : Overlay
+        {
+            private IEntityLookup _lookup;
+            private IEyeManager _eyeManager;
+            private IMapManager _mapManager;
+
+            private RenderingTreeSystem _tree;
+
+            public override OverlaySpace Space => OverlaySpace.WorldSpace;
+
+            public DebugLightOverlay(IEntityLookup lookup, IEyeManager eyeManager, IMapManager mapManager, RenderingTreeSystem tree)
+            {
+                _lookup = lookup;
+                _eyeManager = eyeManager;
+                _mapManager = mapManager;
+                _tree = tree;
+            }
+
+            protected internal override void Draw(in OverlayDrawArgs args)
+            {
+                var map = _eyeManager.CurrentMap;
+                if (map == MapId.Nullspace) return;
+
+                var viewport = _eyeManager.GetWorldViewport();
+
+                foreach (var tree in _tree.GetLightTrees(map, viewport))
+                {
+                    foreach (var light in tree)
+                    {
+                        var aabb = _lookup.GetWorldAabbFromEntity(light.Owner);
+                        if (!aabb.Intersects(viewport)) continue;
+
+                        args.WorldHandle.DrawRect(aabb, Color.Green.WithAlpha(0.1f));
+                    }
+                }
+            }
+        }
+    }
+}
+#endif

Robust.Client/GameObjects/EntitySystems/InputSystem.cs

@@ -173,4 +173,24 @@ namespace Robust.Client.GameObjects
             AttachedEntity = attachedEntity;
         }
     }
+
+    public class PlayerAttachedEvent : EntityEventArgs
+    {
+        public PlayerAttachedEvent(IEntity entity)
+        {
+            Entity = entity;
+        }
+
+        public IEntity Entity { get; }
+    }
+
+    public class PlayerDetachedEvent : EntityEventArgs
+    {
+        public PlayerDetachedEvent(IEntity entity)
+        {
+            Entity = entity;
+        }
+
+        public IEntity Entity { get; }
+    }
 }

Robust.Client/GameObjects/EntitySystems/RenderingTreeSystem.cs

@@ -3,8 +3,11 @@ using System.Drawing;
 using System.Linq;
 using JetBrains.Annotations;
 using Robust.Client.Physics;
+using Robust.Shared;
+using Robust.Shared.Configuration;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
+using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Physics;
@@ -18,23 +21,58 @@ namespace Robust.Client.GameObjects
     [UsedImplicitly]
     public sealed class RenderingTreeSystem : EntitySystem
     {
+        internal const string LoggerSawmill = "rendertree";
+
         // Nullspace is not indexed. Keep that in mind.
 
-        [Dependency] private readonly IMapManagerInternal _mapManager = default!;
-
-        private readonly Dictionary<MapId, Dictionary<GridId, MapTrees>> _gridTrees = new();
+        [Dependency] private readonly IMapManager _mapManager = default!;
 
         private readonly List<SpriteComponent> _spriteQueue = new();
         private readonly List<PointLightComponent> _lightQueue = new();
 
-        internal DynamicTree<SpriteComponent> GetSpriteTreeForMap(MapId map, GridId grid)
+        private HashSet<EntityUid> _checkedChildren = new();
+
+        /// <summary>
+        /// <see cref="CVars.MaxLightRadius"/>
+        /// </summary>
+        public float MaxLightRadius { get; private set; }
+
+        internal IEnumerable<RenderingTreeComponent> GetRenderTrees(MapId mapId, Box2 worldAABB)
         {
-            return _gridTrees[map][grid].SpriteTree;
+            if (mapId == MapId.Nullspace) yield break;
+
+            var enclosed = false;
+
+            foreach (var grid in _mapManager.FindGridsIntersecting(mapId, worldAABB))
+            {
+                yield return EntityManager.GetEntity(grid.GridEntityId).GetComponent<RenderingTreeComponent>();
+
+                // if we're enclosed then we know no other grids relevant + don't need the map's rendertree
+                if (grid.WorldBounds.Encloses(in worldAABB))
+                {
+                    enclosed = true;
+                    break;
+                }
+            }
+
+            if (!enclosed)
+                yield return _mapManager.GetMapEntity(mapId).GetComponent<RenderingTreeComponent>();
         }
 
-        internal DynamicTree<PointLightComponent> GetLightTreeForMap(MapId map, GridId grid)
+        internal IEnumerable<DynamicTree<SpriteComponent>> GetSpriteTrees(MapId mapId, Box2 worldAABB)
         {
-            return _gridTrees[map][grid].LightTree;
+            foreach (var comp in GetRenderTrees(mapId, worldAABB))
+            {
+                yield return comp.SpriteTree;
+            }
+        }
+
+        internal IEnumerable<DynamicTree<PointLightComponent>> GetLightTrees(MapId mapId, Box2 worldAABB)
+        {
+            foreach (var comp in GetRenderTrees(mapId, worldAABB))
+            {
+                yield return comp.LightTree;
+            }
         }
 
         public override void Initialize()
@@ -46,23 +84,38 @@ namespace Robust.Client.GameObjects
             UpdatesAfter.Add(typeof(PhysicsSystem));
 
             _mapManager.MapCreated += MapManagerOnMapCreated;
-            _mapManager.MapDestroyed += MapManagerOnMapDestroyed;
             _mapManager.OnGridCreated += MapManagerOnGridCreated;
-            _mapManager.OnGridRemoved += MapManagerOnGridRemoved;
 
             // Due to how recursion works, this must be done.
             SubscribeLocalEvent<MoveEvent>(AnythingMoved);
 
             SubscribeLocalEvent<SpriteComponent, EntMapIdChangedMessage>(SpriteMapChanged);
-            SubscribeLocalEvent<SpriteComponent, MoveEvent>(SpriteMoved);
             SubscribeLocalEvent<SpriteComponent, EntParentChangedMessage>(SpriteParentChanged);
             SubscribeLocalEvent<SpriteComponent, ComponentRemove>(RemoveSprite);
+            SubscribeLocalEvent<SpriteComponent, SpriteUpdateEvent>(HandleSpriteUpdate);
 
             SubscribeLocalEvent<PointLightComponent, EntMapIdChangedMessage>(LightMapChanged);
-            SubscribeLocalEvent<PointLightComponent, MoveEvent>(LightMoved);
             SubscribeLocalEvent<PointLightComponent, EntParentChangedMessage>(LightParentChanged);
             SubscribeLocalEvent<PointLightComponent, PointLightRadiusChangedEvent>(PointLightRadiusChanged);
             SubscribeLocalEvent<PointLightComponent, RenderTreeRemoveLightEvent>(RemoveLight);
+            SubscribeLocalEvent<PointLightComponent, PointLightUpdateEvent>(HandleLightUpdate);
+
+            SubscribeLocalEvent<RenderingTreeComponent, ComponentRemove>(HandleTreeRemove);
+
+            var configManager = IoCManager.Resolve<IConfigurationManager>();
+            configManager.OnValueChanged(CVars.MaxLightRadius, value => MaxLightRadius = value, true);
+        }
+
+        private void HandleLightUpdate(EntityUid uid, PointLightComponent component, PointLightUpdateEvent args)
+        {
+            if (component.TreeUpdateQueued) return;
+            QueueLightUpdate(component);
+        }
+
+        private void HandleSpriteUpdate(EntityUid uid, SpriteComponent component, SpriteUpdateEvent args)
+        {
+            if (component.TreeUpdateQueued) return;
+            QueueSpriteUpdate(component);
         }
 
         private void AnythingMoved(MoveEvent args)
@@ -72,13 +125,20 @@ namespace Robust.Client.GameObjects
 
         private void AnythingMovedSubHandler(ITransformComponent sender)
         {
+            // To avoid doing redundant updates (and we don't need to update a grid's children ever)
+            if (!_checkedChildren.Add(sender.Owner.Uid) ||
+                sender.Owner.HasComponent<RenderingTreeComponent>()) return;
+
             // This recursive search is needed, as MoveEvent is defined to not care about indirect events like children.
             // WHATEVER YOU DO, DON'T REPLACE THIS WITH SPAMMING EVENTS UNLESS YOU HAVE A GUARANTEE IT WON'T LAG THE GC.
             // (Struct-based events ok though)
+            // Ironically this was lagging the GC lolz
             if (sender.Owner.TryGetComponent(out SpriteComponent? sprite))
                 QueueSpriteUpdate(sprite);
+
             if (sender.Owner.TryGetComponent(out PointLightComponent? light))
                 QueueLightUpdate(light);
+
             foreach (ITransformComponent child in sender.Children)
             {
                 AnythingMovedSubHandler(child);
@@ -96,11 +156,6 @@ namespace Robust.Client.GameObjects
             QueueSpriteUpdate(component);
         }
 
-        private void SpriteMoved(EntityUid uid, SpriteComponent component, MoveEvent args)
-        {
-            QueueSpriteUpdate(component);
-        }
-
         private void SpriteParentChanged(EntityUid uid, SpriteComponent component, EntParentChangedMessage args)
         {
             QueueSpriteUpdate(component);
@@ -113,16 +168,10 @@ namespace Robust.Client.GameObjects
 
         private void ClearSprite(SpriteComponent component)
         {
-            if (_gridTrees.TryGetValue(component.IntersectingMapId, out var gridTrees))
-            {
-                foreach (var gridId in component.IntersectingGrids)
-                {
-                    if (!gridTrees.TryGetValue(gridId, out var tree)) continue;
-                    tree.SpriteTree.Remove(component);
-                }
-            }
+            if (component.RenderTree == null) return;
 
-            component.IntersectingGrids.Clear();
+            component.RenderTree.SpriteTree.Remove(component);
+            component.RenderTree = null;
         }
 
         private void QueueSpriteUpdate(SpriteComponent component)
@@ -131,22 +180,6 @@ namespace Robust.Client.GameObjects
 
             component.TreeUpdateQueued = true;
             _spriteQueue.Add(component);
-
-            foreach (var child in component.Owner.Transform.Children)
-            {
-                QueueSpriteUpdate(child.Owner);
-            }
-        }
-
-        private void QueueSpriteUpdate(IEntity entity)
-        {
-            if (!entity.TryGetComponent(out SpriteComponent? spriteComponent)) return;
-            QueueSpriteUpdate(spriteComponent);
-
-            foreach (var child in entity.Transform.Children)
-            {
-                QueueSpriteUpdate(child.Owner);
-            }
         }
         #endregion
 
@@ -156,11 +189,6 @@ namespace Robust.Client.GameObjects
             QueueLightUpdate(component);
         }
 
-        private void LightMoved(EntityUid uid, PointLightComponent component, MoveEvent args)
-        {
-            QueueLightUpdate(component);
-        }
-
         private void LightParentChanged(EntityUid uid, PointLightComponent component, EntParentChangedMessage args)
         {
             QueueLightUpdate(component);
@@ -178,16 +206,10 @@ namespace Robust.Client.GameObjects
 
         private void ClearLight(PointLightComponent component)
         {
-            if (_gridTrees.TryGetValue(component.IntersectingMapId, out var gridTrees))
-            {
-                foreach (var gridId in component.IntersectingGrids)
-                {
-                    if (!gridTrees.TryGetValue(gridId, out var tree)) continue;
-                    tree.LightTree.Remove(component);
-                }
-            }
+            if (component.RenderTree == null) return;
 
-            component.IntersectingGrids.Clear();
+            component.RenderTree.LightTree.Remove(component);
+            component.RenderTree = null;
         }
 
         private void QueueLightUpdate(PointLightComponent component)
@@ -196,22 +218,6 @@ namespace Robust.Client.GameObjects
 
             component.TreeUpdateQueued = true;
             _lightQueue.Add(component);
-
-            foreach (var child in component.Owner.Transform.Children)
-            {
-                QueueLightUpdate(child.Owner);
-            }
-        }
-
-        private void QueueLightUpdate(IEntity entity)
-        {
-            if (!entity.TryGetComponent(out PointLightComponent? lightComponent)) return;
-            QueueLightUpdate(lightComponent);
-
-            foreach (var child in entity.Transform.Children)
-            {
-                QueueLightUpdate(child.Owner);
-            }
         }
         #endregion
 
@@ -219,31 +225,23 @@ namespace Robust.Client.GameObjects
         {
             base.Shutdown();
             _mapManager.MapCreated -= MapManagerOnMapCreated;
-            _mapManager.MapDestroyed -= MapManagerOnMapDestroyed;
             _mapManager.OnGridCreated -= MapManagerOnGridCreated;
-            _mapManager.OnGridRemoved -= MapManagerOnGridRemoved;
         }
 
-        private void MapManagerOnMapDestroyed(object? sender, MapEventArgs e)
+        private void HandleTreeRemove(EntityUid uid, RenderingTreeComponent component, ComponentRemove args)
         {
-            foreach (var (_, gridTree) in _gridTrees[e.Map])
+            foreach (var sprite in component.SpriteTree)
             {
-                foreach (var comp in gridTree.LightTree)
-                {
-                    comp.IntersectingGrids.Clear();
-                }
-
-                foreach (var comp in gridTree.SpriteTree)
-                {
-                    comp.IntersectingGrids.Clear();
-                }
-
-                // Just in case?
-                gridTree.LightTree.Clear();
-                gridTree.SpriteTree.Clear();
+                sprite.RenderTree = null;
             }
 
-            _gridTrees.Remove(e.Map);
+            foreach (var light in component.LightTree)
+            {
+                light.RenderTree = null;
+            }
+
+            component.SpriteTree.Clear();
+            component.LightTree.Clear();
         }
 
         private void MapManagerOnMapCreated(object? sender, MapEventArgs e)
@@ -253,154 +251,122 @@ namespace Robust.Client.GameObjects
                 return;
             }
 
-            _gridTrees.Add(e.Map, new Dictionary<GridId, MapTrees>
-            {
-                {GridId.Invalid, new MapTrees()}
-            });
+            _mapManager.GetMapEntity(e.Map).EnsureComponent<RenderingTreeComponent>();
         }
 
         private void MapManagerOnGridCreated(MapId mapId, GridId gridId)
         {
-            _gridTrees[mapId].Add(gridId, new MapTrees());
+            EntityManager.GetEntity(_mapManager.GetGrid(gridId).GridEntityId).EnsureComponent<RenderingTreeComponent>();
         }
 
-        private void MapManagerOnGridRemoved(MapId mapId, GridId gridId)
+        private RenderingTreeComponent? GetRenderTree(IEntity entity)
         {
-            var gridTree = _gridTrees[mapId][gridId];
 
-            foreach (var sprite in gridTree.SpriteTree)
+            if (entity.Transform.MapID == MapId.Nullspace ||
+                entity.HasComponent<RenderingTreeComponent>()) return null;
+
+            var parent = entity.Transform.Parent?.Owner;
+
+            while (true)
             {
-                sprite.IntersectingGrids.Remove(gridId);
+                if (parent == null) break;
+
+                if (parent.TryGetComponent(out RenderingTreeComponent? comp)) return comp;
+                parent = parent.Transform.Parent?.Owner;
             }
 
-            foreach (var light in gridTree.LightTree)
-            {
-                light.IntersectingGrids.Remove(gridId);
-            }
-
-            // Clear in case
-            gridTree.LightTree.Clear();
-            gridTree.SpriteTree.Clear();
-            _gridTrees[mapId].Remove(gridId);
+            return null;
         }
 
         public override void FrameUpdate(float frameTime)
         {
+            _checkedChildren.Clear();
+
             foreach (var sprite in _spriteQueue)
             {
-                var mapId = sprite.Owner.Transform.MapID;
-
-                // If we're on a new map then clear the old one.
-                if (sprite.IntersectingMapId != mapId)
+                sprite.TreeUpdateQueued = false;
+                if (!sprite.Visible || sprite.ContainerOccluded)
                 {
                     ClearSprite(sprite);
+                    continue;
                 }
 
-                sprite.IntersectingMapId = mapId;
+                var oldMapTree = sprite.RenderTree;
+                var newMapTree = GetRenderTree(sprite.Owner);
+                // TODO: Temp PVS guard
+                var worldPos = sprite.Owner.Transform.WorldPosition;
 
-                if (mapId == MapId.Nullspace) continue;
-
-                var mapTree = _gridTrees[mapId];
-                var aabb = MapTrees.SpriteAabbFunc(sprite);
-                var intersectingGrids = _mapManager.FindGridIdsIntersecting(mapId, aabb, true).ToList();
-
-                // Remove from old
-                foreach (var gridId in sprite.IntersectingGrids)
+                if (float.IsNaN(worldPos.X) || float.IsNaN(worldPos.Y))
                 {
-                    if (intersectingGrids.Contains(gridId)) continue;
-                    mapTree[gridId].SpriteTree.Remove(sprite);
+                    ClearSprite(sprite);
+                    continue;
                 }
 
-                // Rebuild in the update below
-                sprite.IntersectingGrids.Clear();
+                var treePos = newMapTree?.Owner.Transform.WorldPosition ?? Vector2.Zero;
+                var aabb = RenderingTreeComponent.SpriteAabbFunc(sprite, worldPos).Translated(-treePos);
 
-                // Update / add to new
-                foreach (var gridId in intersectingGrids)
+                // If we're on a new map then clear the old one.
+                if (oldMapTree != newMapTree)
                 {
-                    var translated = aabb.Translated(gridId == GridId.Invalid
-                        ? Vector2.Zero
-                        : -_mapManager.GetGrid(gridId).WorldPosition);
-
-                    mapTree[gridId].SpriteTree.AddOrUpdate(sprite, translated);
-
-                    sprite.IntersectingGrids.Add(gridId);
+                    ClearSprite(sprite);
+                    newMapTree?.SpriteTree.Add(sprite, aabb);
+                }
+                else
+                {
+                    newMapTree?.SpriteTree.Update(sprite, aabb);
                 }
 
-                sprite.TreeUpdateQueued = false;
+                sprite.RenderTree = newMapTree;
             }
 
             foreach (var light in _lightQueue)
             {
-                var mapId = light.Owner.Transform.MapID;
+                light.TreeUpdateQueued = false;
 
-                // If we're on a new map then clear the old one.
-                if (light.IntersectingMapId != mapId)
+                if (!light.Enabled || light.ContainerOccluded)
                 {
                     ClearLight(light);
+                    continue;
                 }
 
-                light.IntersectingMapId = mapId;
+                var oldMapTree = light.RenderTree;
+                var newMapTree = GetRenderTree(light.Owner);
+                // TODO: Temp PVS guard
+                var worldPos = light.Owner.Transform.WorldPosition;
 
-                if (mapId == MapId.Nullspace) continue;
-
-                var mapTree = _gridTrees[mapId];
-                var aabb = MapTrees.LightAabbFunc(light);
-                var intersectingGrids = _mapManager.FindGridIdsIntersecting(mapId, aabb, true).ToList();
-
-                // Remove from old
-                foreach (var gridId in intersectingGrids)
+                if (float.IsNaN(worldPos.X) || float.IsNaN(worldPos.Y))
                 {
-                    if (intersectingGrids.Contains(gridId)) continue;
-                    mapTree[gridId].LightTree.Remove(light);
+                    ClearLight(light);
+                    continue;
                 }
 
-                // Rebuild in the update below
-                light.IntersectingGrids.Clear();
-
-                // Update / add to new
-                foreach (var gridId in intersectingGrids)
+                // TODO: Events need a bit of cleanup so we only validate this on initialize and radius changed events
+                // this is fine for now IMO as it's 1 float check for every light that moves
+                if (light.Radius > MaxLightRadius)
                 {
-                    var translated = aabb.Translated(gridId == GridId.Invalid
-                        ? Vector2.Zero
-                        : -_mapManager.GetGrid(gridId).WorldPosition);
-
-                    mapTree[gridId].LightTree.AddOrUpdate(light, translated);
-                    light.IntersectingGrids.Add(gridId);
+                    Logger.WarningS(LoggerSawmill, $"Light radius for {light.Owner} set above max radius of {MaxLightRadius}. This may lead to pop-in.");
                 }
 
-                light.TreeUpdateQueued = false;
+                var treePos = newMapTree?.Owner.Transform.WorldPosition ?? Vector2.Zero;
+                var aabb = RenderingTreeComponent.LightAabbFunc(light, worldPos).Translated(-treePos);
+
+                // If we're on a new map then clear the old one.
+                if (oldMapTree != newMapTree)
+                {
+                    ClearLight(light);
+                    newMapTree?.LightTree.Add(light, aabb);
+                }
+                else
+                {
+                    newMapTree?.LightTree.Update(light, aabb);
+                }
+
+                light.RenderTree = newMapTree;
             }
 
             _spriteQueue.Clear();
             _lightQueue.Clear();
         }
-
-        private sealed class MapTrees
-        {
-            public readonly DynamicTree<SpriteComponent> SpriteTree;
-            public readonly DynamicTree<PointLightComponent> LightTree;
-
-            public MapTrees()
-            {
-                SpriteTree = new DynamicTree<SpriteComponent>(SpriteAabbFunc);
-                LightTree = new DynamicTree<PointLightComponent>(LightAabbFunc);
-            }
-
-            internal static Box2 SpriteAabbFunc(in SpriteComponent value)
-            {
-                var worldPos = value.Owner.Transform.WorldPosition;
-
-                return new Box2(worldPos, worldPos);
-            }
-
-            internal static Box2 LightAabbFunc(in PointLightComponent value)
-            {
-                var worldPos = value.Owner.Transform.WorldPosition;
-
-                var boxSize = value.Radius * 2;
-                return Box2.CenteredAround(worldPos, (boxSize, boxSize));
-            }
-        }
     }
 
     internal class RenderTreeRemoveLightEvent : EntityEventArgs

Robust.Client/GameObjects/EntitySystems/SpriteSystem.cs

@@ -1,9 +1,9 @@
-using JetBrains.Annotations;
+using System.Collections.Generic;
+using JetBrains.Annotations;
 using Robust.Client.Graphics;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
-using Robust.Shared.Maths;
 
 namespace Robust.Client.GameObjects
 {
@@ -17,16 +17,29 @@ namespace Robust.Client.GameObjects
         [Dependency] private readonly IMapManager _mapManager = default!;
 
         private RenderingTreeSystem _treeSystem = default!;
+        private readonly Queue<SpriteComponent> _inertUpdateQueue = new();
 
         public override void Initialize()
         {
             base.Initialize();
+
             _treeSystem = Get<RenderingTreeSystem>();
+            SubscribeLocalEvent<SpriteUpdateInertEvent>(QueueUpdateInert);
+        }
+
+        private void QueueUpdateInert(SpriteUpdateInertEvent ev)
+        {
+            _inertUpdateQueue.Enqueue(ev.Sprite);
         }
 
         /// <inheritdoc />
         public override void FrameUpdate(float frameTime)
         {
+            while (_inertUpdateQueue.TryDequeue(out var sprite))
+            {
+                sprite.DoUpdateIsInert();
+            }
+
             // So we could calculate the correct size of the entities based on the contents of their sprite...
             // Or we can just assume that no entity is larger than 10x10 and get a stupid easy check.
             var pvsBounds = _eyeManager.GetWorldViewport().Enlarged(5);
@@ -37,13 +50,11 @@ namespace Robust.Client.GameObjects
                 return;
             }
 
-            foreach (var gridId in _mapManager.FindGridIdsIntersecting(currentMap, pvsBounds, true))
+            foreach (var comp in _treeSystem.GetRenderTrees(currentMap, pvsBounds))
             {
-                var gridBounds = gridId == GridId.Invalid ? pvsBounds : pvsBounds.Translated(-_mapManager.GetGrid(gridId).WorldPosition);
+                var bounds = pvsBounds.Translated(-comp.Owner.Transform.WorldPosition);
 
-                var mapTree = _treeSystem.GetSpriteTreeForMap(currentMap, gridId);
-
-                mapTree.QueryAabb(ref frameTime, (ref float state, in SpriteComponent value) =>
+                comp.SpriteTree.QueryAabb(ref frameTime, (ref float state, in SpriteComponent value) =>
                 {
                     if (value.IsInert)
                     {
@@ -52,7 +63,7 @@ namespace Robust.Client.GameObjects
 
                     value.FrameUpdate(state);
                     return true;
-                }, gridBounds, approx: true);
+                }, bounds, true);
             }
         }
     }

Robust.Client/GameObjects/IClientEntityManager.cs

@@ -1,4 +1,3 @@
-using System.Collections.Generic;
 using Robust.Shared.GameObjects;
 
 namespace Robust.Client.GameObjects

Robust.Client/GameObjects/PlayerMessages.cs

@@ -1,17 +0,0 @@
-using System;
-using Robust.Shared.GameObjects;
-
-namespace Robust.Client.GameObjects
-{
-    [Obsolete("Component Messages are deprecated, use Entity Events instead.")]
-    public class PlayerAttachedMsg : ComponentMessage
-    {
-
-    }
-
-    [Obsolete("Component Messages are deprecated, use Entity Events instead.")]
-    public class PlayerDetachedMsg : ComponentMessage
-    {
-
-    }
-}

Robust.Client/GameStates/ClientGameStateManager.cs

@@ -210,6 +210,11 @@ namespace Robust.Client.GameStates
                     ResetPredictedEntities(_timing.CurTick);
                 }
 
+                if (!curState.Extrapolated)
+                {
+                    _processor.UpdateFullRep(curState);
+                }
+
                 // Store last tick we got from the GameStateProcessor.
                 _lastProcessedTick = _timing.CurTick;
 
@@ -319,6 +324,8 @@ namespace Robust.Client.GameStates
 
         private void ResetPredictedEntities(GameTick curTick)
         {
+            var bus = (EntityEventBus) _entities.EventBus;
+
             foreach (var entity in _entities.GetEntities())
             {
                 // TODO: 99% there's an off-by-one here.
@@ -347,6 +354,7 @@ namespace Robust.Client.GameStates
 
                     Logger.DebugS(CVars.NetPredict.Name, $"  And also its component {comp.Name}");
                     // TODO: Handle interpolation.
+                    bus.RaiseComponentEvent(comp, new ComponentHandleState(compState, null));
                     comp.HandleComponentState(compState, null);
                 }
             }
@@ -394,7 +402,7 @@ namespace Robust.Client.GameStates
         private List<EntityUid> ApplyGameState(GameState curState, GameState? nextState)
         {
             _config.TickProcessMessages();
-            _mapManager.ApplyGameStatePre(curState.MapData);
+            _mapManager.ApplyGameStatePre(curState.MapData, curState.EntityStates);
             var createdEntities = ApplyEntityStates(curState.EntityStates, curState.EntityDeletions,
                 nextState?.EntityStates);
             _players.ApplyPlayerStates(curState.PlayerStates);
@@ -419,6 +427,7 @@ namespace Robust.Client.GameStates
                     //Known entities
                     if (_entities.TryGetEntity(es.Uid, out var entity))
                     {
+                        // Logger.Debug($"[{IGameTiming.TickStampStatic}] MOD {es.Uid}");
                         toApply.Add(entity, (es, null));
                     }
                     else //Unknown entities
@@ -429,6 +438,7 @@ namespace Robust.Client.GameStates
                         {
                             throw new InvalidOperationException($"Server sent new entity state for {es.Uid} without metadata component!");
                         }
+                        // Logger.Debug($"[{IGameTiming.TickStampStatic}] CREATE {es.Uid} {metaState.PrototypeId}");
                         var newEntity = (Entity)_entities.CreateEntity(metaState.PrototypeId, es.Uid);
                         toApply.Add(newEntity, (es, null));
                         toInitialize.Add(newEntity);
@@ -455,17 +465,20 @@ namespace Robust.Client.GameStates
                 }
             }
 
+            var bus = (EntityEventBus) _entities.EventBus;
+
             // Make sure this is done after all entities have been instantiated.
             foreach (var kvStates in toApply)
             {
                 var ent = kvStates.Key;
                 var entity = (Entity) ent;
-                HandleEntityState(entity.EntityManager.ComponentManager, entity, kvStates.Value.Item1,
+                HandleEntityState(entity.EntityManager.ComponentManager, entity, bus, kvStates.Value.Item1,
                     kvStates.Value.Item2);
             }
 
             foreach (var id in deletions)
             {
+                // Logger.Debug($"[{IGameTiming.TickStampStatic}] DELETE {id}");
                 _entities.DeleteEntity(id);
             }
 
@@ -527,7 +540,7 @@ namespace Robust.Client.GameStates
             return created;
         }
 
-        private void HandleEntityState(IComponentManager compMan, IEntity entity, EntityState? curState,
+        private void HandleEntityState(IComponentManager compMan, IEntity entity, EntityEventBus bus, EntityState? curState,
             EntityState? nextState)
         {
             var compStateWork = new Dictionary<uint, (ComponentState? curState, ComponentState? nextState)>();
@@ -585,6 +598,7 @@ namespace Robust.Client.GameStates
                 {
                     try
                     {
+                        bus.RaiseComponentEvent(component, new ComponentHandleState(cur, next));
                         component.HandleComponentState(cur, next);
                     }
                     catch (Exception e)

Robust.Client/GameStates/GameStateProcessor.cs

@@ -149,11 +149,6 @@ namespace Robust.Client.GameStates
                 {
                     Logger.DebugS("net.state", $"Applying State:  ext={curState!.Extrapolated}, cTick={_timing.CurTick}, fSeq={curState.FromSequence}, tSeq={curState.ToSequence}, buf={_stateBuffer.Count}");
                 }
-
-                if (!curState!.Extrapolated)
-                {
-                    UpdateFullRep(curState);
-                }
             }
 
             var cState = curState!;
@@ -162,8 +157,10 @@ namespace Robust.Client.GameStates
             return applyNextState;
         }
 
-        private void UpdateFullRep(GameState state)
+        public void UpdateFullRep(GameState state)
         {
+            // Logger.Debug($"UPDATE FULL REP: {string.Join(", ", state.EntityStates?.Select(e => e.Uid) ?? Enumerable.Empty<EntityUid>())}");
+
             if (state.FromSequence == GameTick.Zero)
             {
                 // Full state.

Robust.Client/GameStates/NetEntityOverlay.cs

@@ -178,7 +178,7 @@ namespace Robust.Client.GameStates
                 var yPos = 10 + _lineHeight * i;
                 var name = $"({netEnt.Id}) {ent.Prototype?.ID}";
                 var color = CalcTextColor(ref netEnt);
-                DrawString(screenHandle, _font, new Vector2(xPos + (TrafficHistorySize + 4), yPos), name, color);
+                screenHandle.DrawString(_font, new Vector2(xPos + (TrafficHistorySize + 4), yPos), name, color);
                 DrawTrafficBox(screenHandle, ref netEnt, xPos, yPos);
             }
         }
@@ -223,17 +223,6 @@ namespace Robust.Client.GameStates
             base.DisposeBehavior();
         }
 
-        private static void DrawString(DrawingHandleScreen handle, Font font, Vector2 pos, string str, Color textColor)
-        {
-            var baseLine = new Vector2(pos.X, font.GetAscent(1) + pos.Y);
-
-            foreach (var rune in str.EnumerateRunes())
-            {
-                var advance = font.DrawChar(handle, rune, baseLine, 1, textColor);
-                baseLine += new Vector2(advance, 0);
-            }
-        }
-
         private struct NetEntity
         {
             public GameTick LastUpdate;

Robust.Client/GameStates/NetGraphOverlay.cs

@@ -184,7 +184,7 @@ namespace Robust.Client.GameStates
                 // Draw size if above average
                 if (drawSizeThreshold * 1.5 < state.Payload)
                 {
-                    DrawString(handle, _font, new Vector2(xOff, yoff - _font.GetLineHeight(1)), state.Payload.ToString());
+                    handle.DrawString(_font, new Vector2(xOff, yoff - _font.GetLineHeight(1)), state.Payload.ToString());
                 }
 
                 // second tick marks
@@ -224,14 +224,14 @@ namespace Robust.Client.GameStates
             handle.DrawLine(new Vector2(leftMargin, midYoff), new Vector2(leftMargin + width, midYoff), Color.DarkGray.WithAlpha(0.8f));
 
             // payload text
-            DrawString(handle, _font, new Vector2(leftMargin + width, warnYoff), "56K");
-            DrawString(handle, _font, new Vector2(leftMargin + width, midYoff), "33.6K");
+            handle.DrawString(_font, new Vector2(leftMargin + width, warnYoff), "56K");
+            handle.DrawString(_font, new Vector2(leftMargin + width, midYoff), "33.6K");
 
             // interp text info
             if(lastLagY != -1)
-                DrawString(handle, _font, new Vector2(leftMargin + width, lastLagY), $"{lastLagMs.ToString()}ms");
+                handle.DrawString(_font, new Vector2(leftMargin + width, lastLagY), $"{lastLagMs.ToString()}ms");
 
-            DrawString(handle, _font, new Vector2(leftMargin, height + LowerGraphOffset), $"{_gameStateManager.CurrentBufferSize.ToString()} states");
+            handle.DrawString(_font, new Vector2(leftMargin, height + LowerGraphOffset), $"{_gameStateManager.CurrentBufferSize.ToString()} states");
         }
 
         protected override void DisposeBehavior()
@@ -241,17 +241,6 @@ namespace Robust.Client.GameStates
             base.DisposeBehavior();
         }
 
-        private void DrawString(DrawingHandleScreen handle, Font font, Vector2 pos, string str)
-        {
-            var baseLine = new Vector2(pos.X, font.GetAscent(1) + pos.Y);
-
-            foreach (var rune in str.EnumerateRunes())
-            {
-                var advance = font.DrawChar(handle, rune, baseLine, 1, Color.White);
-                baseLine += new Vector2(advance, 0);
-            }
-        }
-
         private class NetShowGraphCommand : IConsoleCommand
         {
             public string Command => "net_graph";

Robust.Client/Graphics/Clyde/Clyde.DllMap.cs

@@ -11,7 +11,7 @@ namespace Robust.Client.Graphics.Clyde
     {
         static Clyde()
         {
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) &&
+            if (OperatingSystem.IsWindows() &&
                 RuntimeInformation.ProcessArchitecture == Architecture.X64 &&
                 Environment.GetEnvironmentVariable("ROBUST_INTEGRATED_GPU") != "1")
             {
@@ -28,20 +28,20 @@ namespace Robust.Client.Graphics.Clyde
                 }
             }
 
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (OperatingSystem.IsWindows())
             {
                 return;
             }
 
             NativeLibrary.SetDllImportResolver(typeof(GL).Assembly, (name, assembly, path) =>
             {
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux)
+                if (OperatingSystem.IsLinux()
                     && _dllMapLinux.TryGetValue(name, out var mappedName))
                 {
                     return NativeLibrary.Load(mappedName);
                 }
 
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX)
+                if (OperatingSystem.IsMacOS()
                     && _dllMapMacOS.TryGetValue(name, out mappedName))
                 {
                     return NativeLibrary.Load(mappedName);

Robust.Client/Graphics/Clyde/Clyde.HLR.cs

@@ -366,33 +366,14 @@ namespace Robust.Client.Graphics.Clyde
         private void ProcessSpriteEntities(MapId map, Box2 worldBounds,
             RefList<(SpriteComponent sprite, Matrix3 matrix, Angle worldRot, float yWorldPos)> list)
         {
-            var spriteSystem = _entitySystemManager.GetEntitySystem<RenderingTreeSystem>();
-
-            foreach (var gridId in _mapManager.FindGridIdsIntersecting(map, worldBounds, true))
+            foreach (var comp in _entitySystemManager.GetEntitySystem<RenderingTreeSystem>().GetRenderTrees(map, worldBounds))
             {
-                Box2 gridBounds;
+                var bounds = worldBounds.Translated(-comp.Owner.Transform.WorldPosition);
 
-                if (gridId == GridId.Invalid)
-                {
-                    gridBounds = worldBounds;
-                }
-                else
-                {
-                    gridBounds = worldBounds.Translated(-_mapManager.GetGrid(gridId).WorldPosition);
-                }
-
-                var tree = spriteSystem.GetSpriteTreeForMap(map, gridId);
-
-                tree.QueryAabb(ref list, ((
+                comp.SpriteTree.QueryAabb(ref list, ((
                     ref RefList<(SpriteComponent sprite, Matrix3 matrix, Angle worldRot, float yWorldPos)> state,
                     in SpriteComponent value) =>
                 {
-                    // TODO: Probably value in storing this as its own DynamicTree
-                    if (value.ContainerOccluded || !value.Visible)
-                    {
-                        return true;
-                    }
-
                     var entity = value.Owner;
                     var transform = entity.Transform;
 
@@ -404,7 +385,7 @@ namespace Robust.Client.Graphics.Clyde
                     entry.yWorldPos = worldPos.Y;
                     return true;
 
-                }), gridBounds, approx: true);
+                }), bounds, true);
             }
         }
 

Robust.Client/Graphics/Clyde/Clyde.LightRendering.cs

@@ -149,16 +149,16 @@ namespace Robust.Client.Graphics.Clyde
             // FOV FBO.
             _fovRenderTarget = CreateRenderTarget((FovMapSize, 2),
                 new RenderTargetFormatParameters(_hasGLFloatFramebuffers ? RenderTargetColorFormat.RG32F : RenderTargetColorFormat.Rgba8, true),
-                new TextureSampleParameters {WrapMode = TextureWrapMode.Repeat},
+                new TextureSampleParameters { WrapMode = TextureWrapMode.Repeat },
                 nameof(_fovRenderTarget));
 
             if (_hasGLSamplerObjects)
             {
                 _fovFilterSampler = new GLHandle(GL.GenSampler());
-                GL.SamplerParameter(_fovFilterSampler.Handle, SamplerParameterName.TextureMagFilter, (int) All.Linear);
-                GL.SamplerParameter(_fovFilterSampler.Handle, SamplerParameterName.TextureMinFilter, (int) All.Linear);
-                GL.SamplerParameter(_fovFilterSampler.Handle, SamplerParameterName.TextureWrapS, (int) All.Repeat);
-                GL.SamplerParameter(_fovFilterSampler.Handle, SamplerParameterName.TextureWrapT, (int) All.Repeat);
+                GL.SamplerParameter(_fovFilterSampler.Handle, SamplerParameterName.TextureMagFilter, (int)All.Linear);
+                GL.SamplerParameter(_fovFilterSampler.Handle, SamplerParameterName.TextureMinFilter, (int)All.Linear);
+                GL.SamplerParameter(_fovFilterSampler.Handle, SamplerParameterName.TextureWrapS, (int)All.Repeat);
+                GL.SamplerParameter(_fovFilterSampler.Handle, SamplerParameterName.TextureWrapT, (int)All.Repeat);
                 CheckGlError();
             }
 
@@ -180,20 +180,17 @@ namespace Robust.Client.Graphics.Clyde
             _fovCalculationProgram = _compileProgram(depthVert, depthFrag, attribLocations, "Shadow Depth Program");
 
             var debugShader = _resourceCache.GetResource<ShaderSourceResource>("/Shaders/Internal/depth-debug.swsl");
-            _fovDebugShaderInstance = (ClydeShaderInstance) InstanceShader(debugShader.ClydeHandle);
+            _fovDebugShaderInstance = (ClydeShaderInstance)InstanceShader(debugShader.ClydeHandle);
 
             ClydeHandle LoadShaderHandle(string path)
             {
-                try
+                if (_resourceCache.TryGetResource(path, out ShaderSourceResource? resource))
                 {
-                    var shaderSource = _resourceCache.GetResource<ShaderSourceResource>(path);
-                    return shaderSource.ClydeHandle;
-                }
-                catch (Exception ex)
-                {
-                    Logger.Warning($"Can't load shader {path}\n{ex.GetType().Name}: {ex.Message}");
-                    return default;
+                    return resource.ClydeHandle;
                 }
+
+                Logger.Warning($"Can't load shader {path}\n");
+                return default;
             }
 
             _lightSoftShaderHandle = LoadShaderHandle("/Shaders/Internal/light-soft.swsl");
@@ -214,7 +211,7 @@ namespace Robust.Client.Graphics.Clyde
             {
                 // Calculate maximum distance for the projection based on screen size.
                 var screenSizeCut = viewport.Size / EyeManager.PixelsPerMeter;
-                var maxDist = (float) Math.Max(screenSizeCut.X, screenSizeCut.Y);
+                var maxDist = (float)Math.Max(screenSizeCut.X, screenSizeCut.Y);
 
                 // FOV is rendered twice.
                 // Once with back face culling like regular lighting.
@@ -497,24 +494,16 @@ namespace Robust.Client.Graphics.Clyde
             GetLightsToRender(MapId map, in Box2 worldBounds)
         {
             var renderingTreeSystem = _entitySystemManager.GetEntitySystem<RenderingTreeSystem>();
+            var enlargedBounds = worldBounds.Enlarged(renderingTreeSystem.MaxLightRadius);
+
+            // Use worldbounds for this one as we only care if the light intersects our actual bounds
             var state = (this, worldBounds, count: 0);
 
-            foreach (var gridId in _mapManager.FindGridIdsIntersecting(map, worldBounds, true))
+            foreach (var comp in renderingTreeSystem.GetRenderTrees(map, enlargedBounds))
             {
-                Box2 gridBounds;
+                var bounds = worldBounds.Translated(-comp.Owner.Transform.WorldPosition);
 
-                if (gridId == GridId.Invalid)
-                {
-                    gridBounds = worldBounds;
-                }
-                else
-                {
-                    gridBounds = worldBounds.Translated(-_mapManager.GetGrid(gridId).WorldPosition);
-                }
-
-                var lightTree = renderingTreeSystem.GetLightTreeForMap(map, gridId);
-
-                lightTree.QueryAabb(ref state, (ref (Clyde clyde, Box2 worldBounds, int count) state, in PointLightComponent light) =>
+                comp.LightTree.QueryAabb(ref state, (ref (Clyde clyde, Box2 worldBounds, int count) state, in PointLightComponent light) =>
                 {
                     var transform = light.Owner.Transform;
 
@@ -524,12 +513,6 @@ namespace Robust.Client.Graphics.Clyde
                         return false;
                     }
 
-                    // TODO: Don't insert into trees for these, same as sprites.
-                    if (!light.Enabled || light.ContainerOccluded)
-                    {
-                        return true;
-                    }
-
                     var lightPos = transform.WorldMatrix.Transform(light.Offset);
 
                     var circle = new Circle(lightPos, light.Radius);
@@ -544,7 +527,7 @@ namespace Robust.Client.Graphics.Clyde
                     state.clyde._lightsToRenderList[state.count++] = (light, lightPos, distanceSquared);
 
                     return true;
-                }, gridBounds);
+                }, bounds);
             }
 
             if (state.count > _maxLightsPerScene)
@@ -590,7 +573,7 @@ namespace Robust.Client.Graphics.Clyde
 
             SetupGlobalUniformsImmediate(shader, viewport.LightRenderTarget.Texture);
 
-            shader.SetUniformMaybe("size", (Vector2) viewport.WallBleedIntermediateRenderTarget1.Size);
+            shader.SetUniformMaybe("size", (Vector2)viewport.WallBleedIntermediateRenderTarget1.Size);
             shader.SetUniformTextureMaybe(UniIMainTexture, TextureUnit.Texture0);
 
             var size = viewport.WallBleedIntermediateRenderTarget1.Size;
@@ -809,7 +792,7 @@ namespace Robust.Client.Graphics.Clyde
 
                     occluderTree.QueryAabb((in OccluderComponent sOccluder) =>
                     {
-                        var occluder = (ClientOccluderComponent) sOccluder;
+                        var occluder = (ClientOccluderComponent)sOccluder;
                         var transform = occluder.Owner.Transform;
                         if (!occluder.Enabled)
                         {
@@ -893,11 +876,11 @@ namespace Robust.Client.Graphics.Clyde
                                 // DddD
                                 // HHhh
                                 // deflection
-                                arrayVIBuffer[avi++] = (byte) ((((vi + 1) & 2) != 0) ? 0 : 255);
+                                arrayVIBuffer[avi++] = (byte)((((vi + 1) & 2) != 0) ? 0 : 255);
                                 // height
-                                arrayVIBuffer[avi++] = (byte) (((vi & 2) != 0) ? 0 : 255);
+                                arrayVIBuffer[avi++] = (byte)(((vi & 2) != 0) ? 0 : 255);
                             }
-                            QuadBatchIndexWrite(indexBuffer, ref ii, (ushort) aiBase);
+                            QuadBatchIndexWrite(indexBuffer, ref ii, (ushort)aiBase);
                         }
 
                         // North face (TL/TR)
@@ -931,7 +914,7 @@ namespace Robust.Client.Graphics.Clyde
                         arrayMaskBuffer[ami + 3] = new Vector2(blX, blY);
 
                         // Generate mask indices.
-                        QuadBatchIndexWrite(indexMaskBuffer, ref imi, (ushort) ami);
+                        QuadBatchIndexWrite(indexMaskBuffer, ref imi, (ushort)ami);
 
                         ami += 4;
 
@@ -973,7 +956,7 @@ namespace Robust.Client.Graphics.Clyde
             var lightMapSize = GetLightMapSize(viewport.Size);
             var lightMapSizeQuart = GetLightMapSize(viewport.Size, true);
             var lightMapColorFormat = _hasGLFloatFramebuffers ? RenderTargetColorFormat.R11FG11FB10F : RenderTargetColorFormat.Rgba8;
-            var lightMapSampleParameters = new TextureSampleParameters {Filter = true};
+            var lightMapSampleParameters = new TextureSampleParameters { Filter = true };
 
             viewport.LightRenderTarget?.Dispose();
             viewport.WallMaskRenderTarget?.Dispose();
@@ -1010,14 +993,14 @@ namespace Robust.Client.Graphics.Clyde
 
         private Vector2i GetLightMapSize(Vector2i screenSize, bool furtherDivide = false)
         {
-            var divider = (float) _lightmapDivider;
+            var divider = (float)_lightmapDivider;
             if (furtherDivide)
             {
                 divider *= 2;
             }
 
-            var w = (int) Math.Ceiling(screenSize.X / divider);
-            var h = (int) Math.Ceiling(screenSize.Y / divider);
+            var w = (int)Math.Ceiling(screenSize.X / divider);
+            var h = (int)Math.Ceiling(screenSize.Y / divider);
 
             return (w, h);
         }
@@ -1043,7 +1026,7 @@ namespace Robust.Client.Graphics.Clyde
             // Shadow FBO.
             _shadowRenderTarget = CreateRenderTarget((ShadowMapSize, _maxLightsPerScene),
                 new RenderTargetFormatParameters(_hasGLFloatFramebuffers ? RenderTargetColorFormat.RG32F : RenderTargetColorFormat.Rgba8, true),
-                new TextureSampleParameters {WrapMode = TextureWrapMode.Repeat, Filter = true},
+                new TextureSampleParameters { WrapMode = TextureWrapMode.Repeat, Filter = true },
                 nameof(_shadowRenderTarget));
         }
 

Robust.Client/Graphics/Clyde/Clyde.Windowing.cs

@@ -131,7 +131,7 @@ namespace Robust.Client.Graphics.Clyde
 
             if (!succeeded)
             {
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                if (OperatingSystem.IsWindows())
                 {
                     var msgBoxContent = "Failed to create the game window. " +
                                         "This probably means your GPU is too old to play the game. " +
@@ -164,7 +164,7 @@ namespace Robust.Client.Graphics.Clyde
 
         private IEnumerable<Image<Rgba32>> LoadWindowIcons()
         {
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            if (OperatingSystem.IsMacOS())
             {
                 // Does nothing on macOS so don't bother.
                 yield break;

Robust.Client/Graphics/Clyde/Windowing/Glfw.WindowThread.cs

@@ -1,4 +1,4 @@
-using System.Runtime.InteropServices;
+using System;
 using System.Threading.Channels;
 using System.Threading.Tasks;
 using OpenToolkit.GraphicsLibraryFramework;
@@ -13,11 +13,6 @@ namespace Robust.Client.Graphics.Clyde
     {
         private sealed partial class GlfwWindowingImpl
         {
-            // glfwPostEmptyEvent is broken on macOS and crashes when not called from the main thread
-            // (despite what the docs claim, and yes this makes it useless).
-            // Because of this, we just forego it and use glfwWaitEventsTimeout on macOS instead.
-            private static readonly bool IsMacOS = RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
-
             private bool _windowingRunning;
             private ChannelWriter<CmdBase> _cmdWriter = default!;
             private ChannelReader<CmdBase> _cmdReader = default!;
@@ -53,7 +48,10 @@ namespace Robust.Client.Graphics.Clyde
 
                 while (_windowingRunning)
                 {
-                    if (IsMacOS)
+                    // glfwPostEmptyEvent is broken on macOS and crashes when not called from the main thread
+                    // (despite what the docs claim, and yes this makes it useless).
+                    // Because of this, we just forego it and use glfwWaitEventsTimeout on macOS instead.
+                    if (OperatingSystem.IsMacOS())
                         GLFW.WaitEventsTimeout(0.008);
                     else
                         GLFW.WaitEvents();
@@ -157,7 +155,7 @@ namespace Robust.Client.Graphics.Clyde
                 _cmdWriter.TryWrite(cmd);
 
                 // Post empty event to unstuck WaitEvents if necessary.
-                if (!IsMacOS)
+                if (!OperatingSystem.IsMacOS())
                     GLFW.PostEmptyEvent();
             }
 

Robust.Client/Graphics/Clyde/Windowing/Glfw.Windows.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Runtime.InteropServices;
+using System.Runtime.Loader;
 using System.Threading.Tasks;
 using OpenToolkit;
 using OpenToolkit.Graphics.OpenGL4;
@@ -33,6 +34,7 @@ namespace Robust.Client.Graphics.Clyde
             private GlfwWindowReg? _mainWindow;
             private GlfwBindingsContext _mainGraphicsContext = default!;
             private int _nextWindowId = 1;
+            private static bool _eglLoaded;
 
             public async Task<WindowHandle> WindowCreate(WindowCreateParameters parameters)
             {
@@ -474,6 +476,20 @@ namespace Robust.Client.Graphics.Clyde
                     GLFW.WindowHint(WindowHintContextApi.ContextCreationApi, ContextApi.EglContextApi);
                     GLFW.WindowHint(WindowHintOpenGlProfile.OpenGlProfile, OpenGlProfile.Any);
                     GLFW.WindowHint(WindowHintBool.SrgbCapable, false);
+
+                    if (!_eglLoaded && OperatingSystem.IsWindows())
+                    {
+                        // On non-published builds (so, development), GLFW can't find libEGL.dll
+                        // because it'll be in runtimes/<rid>/native/ instead of next to the actual executable.
+                        // We manually preload the library here so that GLFW will find it when it does its thing.
+                        NativeLibrary.TryLoad(
+                            "libEGL.dll",
+                            typeof(Clyde).Assembly,
+                            DllImportSearchPath.SafeDirectories,
+                            out _);
+
+                        _eglLoaded = true;
+                    }
                 }
 
 

Robust.Client/Graphics/Drawing/DrawingHandleScreen.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Text;
 using Robust.Shared.Maths;
 
 namespace Robust.Client.Graphics
@@ -39,5 +40,57 @@ namespace Robust.Client.Graphics
             DrawPrimitiveTopology type = filled ? DrawPrimitiveTopology.TriangleFan : DrawPrimitiveTopology.LineStrip;
             DrawPrimitives(type, buffer, color);
         }
+
+        /// <summary>
+        ///     Draw a simple string to the screen at the specified position.
+        /// </summary>
+        /// <remarks>
+        ///     This method is primarily intended for debug purposes and does not handle things like UI scaling.
+        /// </remarks>
+        /// <returns>
+        ///     The space taken up (horizontal and vertical) by the text.
+        /// </returns>
+        /// <param name="font">The font to render with.</param>
+        /// <param name="pos">The top-left corner to start drawing text at.</param>
+        /// <param name="str">The text to draw.</param>
+        /// <param name="color">The color of text to draw.</param>
+        public Vector2 DrawString(Font font, Vector2 pos, string str, Color color)
+        {
+            var advanceTotal = Vector2.Zero;
+            var baseLine = new Vector2(pos.X, font.GetAscent(1) + pos.Y);
+            var lineHeight = font.GetLineHeight(1);
+
+            foreach (var rune in str.EnumerateRunes())
+            {
+                if (rune == new Rune('\n'))
+                {
+                    baseLine.X = pos.X;
+                    baseLine.Y += lineHeight;
+                    advanceTotal.Y += lineHeight;
+                    continue;
+                }
+
+                var advance = font.DrawChar(this, rune, baseLine, 1, color);
+                advanceTotal.X += advance;
+                baseLine += new Vector2(advance, 0);
+            }
+
+            return advanceTotal;
+        }
+
+        /// <summary>
+        ///     Draw a simple string to the screen at the specified position.
+        /// </summary>
+        /// <remarks>
+        ///     This method is primarily intended for debug purposes and does not handle things like UI scaling.
+        /// </remarks>
+        /// <returns>
+        ///     The space taken up (horizontal and vertical) by the text.
+        /// </returns>
+        /// <param name="font">The font to render with.</param>
+        /// <param name="pos">The top-left corner to start drawing text at.</param>
+        /// <param name="str">The text to draw.</param>
+        public Vector2 DrawString(Font font, Vector2 pos, string str)
+            => DrawString(font, pos, str, Color.White);
     }
 }

Robust.Client/Input/InputDevices.cs

@@ -1,7 +1,6 @@
-using System.Collections.Generic;
-using System.Runtime.InteropServices;
+using System;
+using System.Collections.Generic;
 using Robust.Shared.Localization;
-using Robust.Shared.Map;
 
 namespace Robust.Client.Input
 {
@@ -179,9 +178,9 @@ namespace Robust.Client.Input
             var locId = $"input-key-{key}";
             if (key == Key.LSystem || key == Key.RSystem)
             {
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                if (OperatingSystem.IsWindows())
                     locId += "-win";
-                else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+                else if (OperatingSystem.IsMacOS())
                     locId += "-mac";
                 else
                     locId += "-linux";

Robust.Client/Map/ClientMapManager.cs

@@ -1,72 +1,111 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameStates;
-using Robust.Shared.IoC;
-using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
-using Robust.Shared.Network;
 using Robust.Shared.Utility;
 
 namespace Robust.Client.Map
 {
     internal class ClientMapManager : MapManager, IClientMapManager
     {
-        [Dependency] private readonly INetManager _netManager = default!;
-
-        public void ApplyGameStatePre(GameStateMapData? data)
+        public void ApplyGameStatePre(GameStateMapData? data, EntityState[]? entityStates)
         {
             // There was no map data this tick, so nothing to do.
             if(data == null)
                 return;
 
-            var createdGrids = data.CreatedGrids != null
-                ? new Dictionary<GridId, GameStateMapData.GridCreationDatum>(data.CreatedGrids)
-                : null;
-
             // First we need to figure out all the NEW MAPS.
             if(data.CreatedMaps != null)
             {
+                DebugTools.Assert(entityStates is not null, "Received new maps, but no entity state.");
+
                 foreach (var mapId in data.CreatedMaps)
                 {
+                    // map already exists from a previous state.
                     if (_maps.Contains(mapId))
-                    {
                         continue;
-                    }
 
-                    CreateMap(mapId);
+                    EntityUid mapEuid = default;
+
+                    //get shared euid of map comp entity
+                    foreach (var entityState in entityStates!)
+                    {
+                        if(entityState.ComponentStates is null)
+                            continue;
+
+                        foreach (var compState in entityState.ComponentStates)
+                        {
+                            if (compState is not MapComponentState mapCompState || mapCompState.MapId != mapId)
+                                continue;
+
+                            mapEuid = entityState.Uid;
+                            goto BreakMapEntSearch;
+                        }
+                    }
+                    BreakMapEntSearch:
+
+                    DebugTools.Assert(mapEuid != default, $"Could not find corresponding entity state for new map {mapId}.");
+
+                    CreateMap(mapId, mapEuid);
                 }
             }
 
             // Then make all the grids.
             if(data.CreatedGrids != null)
             {
-                var gridData = data.GridData != null
-                    ? new Dictionary<GridId, GameStateMapData.GridDatum>(data.GridData)
-                    : null;
-
-                DebugTools.AssertNotNull(createdGrids);
+                DebugTools.Assert(data.GridData is not null, "Received new grids, but GridData was null.");
 
                 foreach (var (gridId, creationDatum) in data.CreatedGrids)
                 {
                     if (_grids.ContainsKey(gridId))
-                    {
                         continue;
+
+                    EntityUid gridEuid = default;
+
+                    //get shared euid of map comp entity
+                    foreach (var entityState in entityStates!)
+                    {
+                        if(entityState.ComponentStates is null)
+                            continue;
+
+                        foreach (var compState in entityState.ComponentStates)
+                        {
+                            if (compState is not MapGridComponentState gridCompState || gridCompState.GridIndex != gridId)
+                                continue;
+
+                            gridEuid = entityState.Uid;
+                            goto BreakGridEntSearch;
+                        }
+                    }
+                    BreakGridEntSearch:
+
+                    DebugTools.Assert(gridEuid != default, $"Could not find corresponding entity state for new grid {gridId}.");
+
+                    MapId gridMapId = default;
+                    foreach (var kvData in data.GridData!)
+                    {
+                        if (kvData.Key != gridId)
+                            continue;
+
+                        gridMapId = kvData.Value.Coordinates.MapId;
+                        break;
                     }
 
-                    CreateGrid(gridData![gridId].Coordinates.MapId, gridId, creationDatum.ChunkSize);
+                    DebugTools.Assert(gridMapId != default, $"Could not find corresponding gridData for new grid {gridId}.");
+
+                    CreateGrid(gridMapId, gridId, creationDatum.ChunkSize, gridEuid);
                 }
             }
 
+            // Process all grid updates.
             if(data.GridData != null)
             {
                 SuppressOnTileChanged = true;
                 // Ok good all the grids and maps exist now.
                 foreach (var (gridId, gridDatum) in data.GridData)
                 {
-
                     var grid = _grids[gridId];
                     if (grid.ParentMapId != gridDatum.Coordinates.MapId)
                     {
@@ -112,99 +151,9 @@ namespace Robust.Client.Map
 
         public void ApplyGameStatePost(GameStateMapData? data)
         {
-            DebugTools.Assert(_netManager.IsClient, "Only the client should call this.");
-
             if(data == null) // if there is no data, there is nothing to do!
                 return;
 
-            // maps created on the client in pre-state are linked to client entities
-            // resolve new maps with their shared component that the server just gave us
-            // and delete the client entities
-            if (data.CreatedMaps != null)
-            {
-                foreach (var mapId in data.CreatedMaps)
-                {
-                    // CreateMap should have set this
-                    DebugTools.Assert(_mapEntities.ContainsKey(mapId));
-
-                    // this was already linked in a previous state.
-                    if(!_mapEntities[mapId].IsClientSide())
-                        continue;
-
-                    // get the existing client entity for the map.
-                    var cEntity = EntityManager.GetEntity(_mapEntities[mapId]);
-
-                    // locate the entity that represents this map that was just sent to us
-                    IEntity? sharedMapEntity = null;
-                    var mapComps = EntityManager.ComponentManager.EntityQuery<IMapComponent>(true);
-                    foreach (var mapComp in mapComps)
-                    {
-                        if (!mapComp.Owner.Uid.IsClientSide() && mapComp.WorldMap == mapId)
-                        {
-                            sharedMapEntity = mapComp.Owner;
-                            _mapEntities[mapId] = mapComp.Owner.Uid;
-                            Logger.DebugS("map", $"Map {mapId} pivoted bound entity from {cEntity.Uid} to {mapComp.Owner.Uid}.");
-                            break;
-                        }
-                    }
-
-                    // verify shared entity was found (the server sent us one)
-                    DebugTools.AssertNotNull(sharedMapEntity);
-                    DebugTools.Assert(!_mapEntities[mapId].IsClientSide());
-
-                    // Transfer client child grids made in GameStatePre to the shared component
-                    // so they are not deleted
-                    foreach (var childGridTrans in cEntity.Transform.Children.ToList())
-                    {
-                        childGridTrans.AttachParent(sharedMapEntity!);
-                    }
-
-                    // remove client entity
-                    var cGridComp = cEntity.GetComponent<IMapComponent>();
-                    cGridComp.ClearMapId();
-                    cEntity.Delete();
-                }
-            }
-
-
-            // grids created on the client in pre-state are linked to client entities
-            // resolve new grids with their shared component that the server just gave us
-            // and delete the client entities
-            if (data.CreatedGrids != null)
-            {
-                foreach (var kvNewGrid in data.CreatedGrids)
-                {
-                    var grid = _grids[kvNewGrid.Key];
-
-                    // this was already linked in a previous state.
-                    if(!grid.GridEntityId.IsClientSide())
-                        continue;
-
-                    // remove the existing client entity.
-                    var cEntity = EntityManager.GetEntity(grid.GridEntityId);
-                    var cGridComp = cEntity.GetComponent<IMapGridComponent>();
-
-                    // prevents us from deleting the grid when deleting the grid entity
-                    if(cEntity.Uid.IsClientSide())
-                        cGridComp.ClearGridId();
-
-                    cEntity.Delete(); // normal entities are already parented to the shared comp, client comp has no children
-
-                    var gridComps = EntityManager.ComponentManager.EntityQuery<IMapGridComponent>(true);
-                    foreach (var gridComp in gridComps)
-                    {
-                        if (gridComp.GridIndex == kvNewGrid.Key)
-                        {
-                            grid.GridEntityId = gridComp.Owner.Uid;
-                            Logger.DebugS("map", $"Grid {grid.Index} pivoted bound entity from {cEntity.Uid} to {grid.GridEntityId}.");
-                            break;
-                        }
-                    }
-
-                    DebugTools.Assert(!grid.GridEntityId.IsClientSide());
-                }
-            }
-
             if(data.DeletedGrids != null)
             {
                 foreach (var grid in data.DeletedGrids)

Robust.Client/Map/IClientMapManager.cs

@@ -1,3 +1,4 @@
+using Robust.Shared.GameObjects;
 using Robust.Shared.GameStates;
 using Robust.Shared.Map;
 
@@ -7,7 +8,7 @@ namespace Robust.Client.Map
     {
         // Two methods here, so that new grids etc can be made BEFORE entities get states applied,
         // but old ones can be deleted after.
-        void ApplyGameStatePre(GameStateMapData? data);
+        void ApplyGameStatePre(GameStateMapData? data, EntityState[]? entityStates);
         void ApplyGameStatePost(GameStateMapData? data);
     }
 }

Robust.Client/Placement/PlacementManager.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using Robust.Client.GameObjects;
@@ -25,7 +25,6 @@ namespace Robust.Client.Placement
 {
     public partial class PlacementManager : IPlacementManager, IDisposable
     {
-        [Dependency] public readonly IPhysicsManager PhysicsManager = default!;
         [Dependency] private readonly IClientNetManager NetworkManager = default!;
         [Dependency] public readonly IPlayerManager PlayerManager = default!;
         [Dependency] public readonly IResourceCache ResourceCache = default!;

Robust.Client/Player/LocalPlayer.cs

@@ -1,6 +1,5 @@
-using System;
+using System;
 using Robust.Client.GameObjects;
-using Robust.Shared.Configuration;
 using Robust.Shared.Enums;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Network;
@@ -71,10 +70,10 @@ namespace Robust.Client.Player
             eye.Current = true;
 
             EntityAttached?.Invoke(new EntityAttachedEventArgs(entity));
-            entity.SendMessage(null, new PlayerAttachedMsg());
 
             // notify ECS Systems
             ControlledEntity.EntityManager.EventBus.RaiseEvent(EventSource.Local, new PlayerAttachSysMessage(ControlledEntity));
+            ControlledEntity.EntityManager.EventBus.RaiseLocalEvent(ControlledEntity.Uid, new PlayerAttachedEvent(ControlledEntity));
         }
 
         /// <summary>
@@ -83,13 +82,13 @@ namespace Robust.Client.Player
         public void DetachEntity()
         {
             var previous = ControlledEntity;
-            if (previous != null && previous.Initialized && !previous.Deleted)
+            if (previous is {Initialized: true, Deleted: false})
             {
                 previous.GetComponent<EyeComponent>().Current = false;
-                previous.SendMessage(null, new PlayerDetachedMsg());
 
                 // notify ECS Systems
                 previous.EntityManager.EventBus.RaiseEvent(EventSource.Local, new PlayerAttachSysMessage(null));
+                previous.EntityManager.EventBus.RaiseLocalEvent(previous.Uid, new PlayerDetachedEvent(previous));
             }
 
             ControlledEntity = null;

Robust.Client/UserInterface/Controls/ItemList.cs

@@ -318,6 +318,8 @@ namespace Robust.Client.UserInterface.Controls
         {
             base.Draw(handle);
 
+            var sizeBox = PixelSizeBox;
+
             var font = ActualFont;
             var listBg = ActualBackground;
             var iconBg = ActualItemBackground;
@@ -346,31 +348,38 @@ namespace Robust.Client.UserInterface.Controls
                     itemHeight = item.IconSize.Y;
                 }
 
-                itemHeight = Math.Max(itemHeight, ActualFont.GetHeight(UIScale));
+                itemHeight = Math.Max(itemHeight, font.GetHeight(UIScale));
                 itemHeight += ActualItemBackground.MinimumSize.Y;
 
-                item.Region = UIBox2.FromDimensions(0, offset, PixelWidth, itemHeight);
+                var region = UIBox2.FromDimensions(0, offset, PixelWidth, itemHeight);
+                item.Region = region;
 
-                bg.Draw(handle, item.Region.Value);
-
-                var contentBox = bg.GetContentBox(item.Region.Value);
-                var drawOffset = contentBox.TopLeft;
-                if (item.Icon != null)
+                if (region.Intersects(sizeBox))
                 {
-                    if (item.IconRegion.Size == Vector2.Zero)
-                    {
-                        handle.DrawTextureRect(item.Icon, UIBox2.FromDimensions(drawOffset, item.Icon.Size), item.IconModulate);
-                    }
-                    else
-                    {
-                        handle.DrawTextureRectRegion(item.Icon, UIBox2.FromDimensions(drawOffset, item.Icon.Size), item.IconRegion, item.IconModulate);
-                    }
-                }
+                    bg.Draw(handle, item.Region.Value);
 
-                if (item.Text != null)
-                {
-                    var textBox = new UIBox2(contentBox.Left + item.IconSize.X, contentBox.Top, contentBox.Right, contentBox.Bottom);
-                    DrawTextInternal(handle, item.Text, textBox);
+                    var contentBox = bg.GetContentBox(item.Region.Value);
+                    var drawOffset = contentBox.TopLeft;
+                    if (item.Icon != null)
+                    {
+                        if (item.IconRegion.Size == Vector2.Zero)
+                        {
+                            handle.DrawTextureRect(item.Icon, UIBox2.FromDimensions(drawOffset, item.Icon.Size),
+                                item.IconModulate);
+                        }
+                        else
+                        {
+                            handle.DrawTextureRectRegion(item.Icon, UIBox2.FromDimensions(drawOffset, item.Icon.Size),
+                                item.IconRegion, item.IconModulate);
+                        }
+                    }
+
+                    if (item.Text != null)
+                    {
+                        var textBox = new UIBox2(contentBox.Left + item.IconSize.X, contentBox.Top, contentBox.Right,
+                            contentBox.Bottom);
+                        DrawTextInternal(handle, item.Text, textBox);
+                    }
                 }
 
                 offset += itemHeight;

Robust.Client/UserInterface/Controls/SpriteView.cs

@@ -1,4 +1,4 @@
-using Robust.Client.GameObjects;
+using Robust.Client.GameObjects;
 using Robust.Client.Graphics;
 using Robust.Shared.Maths;
 
@@ -48,7 +48,7 @@ namespace Robust.Client.UserInterface.Controls
                 return;
             }
 
-            renderHandle.DrawEntity(Sprite.Owner, GlobalPixelPosition + PixelSize / 2, Scale, OverrideDirection);
+            renderHandle.DrawEntity(Sprite.Owner, GlobalPixelPosition + PixelSize / 2, Scale * UIScale, OverrideDirection);
         }
     }
 }

Robust.Client/UserInterface/Controls/TabContainer.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using Robust.Client.Graphics;
 using Robust.Shared.Input;
 using Robust.Shared.Localization;
@@ -75,7 +75,7 @@ namespace Robust.Client.UserInterface.Controls
             var control = GetChild(tab);
             var title = control.GetValue(TabTitleProperty);
 
-            return title ?? control.Name ?? Loc.GetString("No title");
+            return title ?? control.Name ?? Loc.GetString("tab-container-not-tab-title-provided");
         }
 
         public static string? GetTabTitle(Control control)

Robust.Client/UserInterface/CustomControls/BaseWindow.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using Robust.Client.UserInterface.Controls;
 using Robust.Shared.Input;
 using Robust.Shared.IoC;
@@ -165,6 +165,8 @@ namespace Robust.Client.UserInterface.CustomControls
 
         protected internal override void MouseExited()
         {
+            base.MouseExited();
+
             if (Resizable && CurrentDrag == DragMode.None)
             {
                 DefaultCursorShape = CursorShape.Arrow;

Robust.Client/UserInterface/CustomControls/EntitySpawnWindow.cs

@@ -65,7 +65,7 @@ namespace Robust.Client.UserInterface.CustomControls
             this.prototypeManager = prototypeManager;
             this.resourceCache = resourceCache;
 
-            Title = Loc.GetString("Entity Spawn Panel");
+            Title = Loc.GetString("entity-spawn-window-title");
 
 
             SetSize = (250, 300);
@@ -83,13 +83,13 @@ namespace Robust.Client.UserInterface.CustomControls
                             (SearchBar = new LineEdit
                             {
                                 HorizontalExpand = true,
-                                PlaceHolder = Loc.GetString("Search")
+                                PlaceHolder = Loc.GetString("entity-spawn-window-search-bar-placeholder")
                             }),
 
                             (ClearButton = new Button
                             {
                                 Disabled = true,
-                                Text = Loc.GetString("Clear"),
+                                Text = Loc.GetString("entity-spawn-window-clear-button"),
                             })
                         }
                     },
@@ -109,13 +109,13 @@ namespace Robust.Client.UserInterface.CustomControls
                             (EraseButton = new Button
                             {
                                 ToggleMode = true,
-                                Text = Loc.GetString("Erase Mode")
+                                Text = Loc.GetString("entity-spawn-window-erase-button-text")
                             }),
 
                             (OverrideMenu = new OptionButton
                             {
                                 HorizontalExpand = true,
-                                ToolTip = Loc.GetString("Override placement")
+                                ToolTip = Loc.GetString("entity-spawn-window-override-menu-tooltip")
                             })
                         }
                     },

Robust.Client/UserInterface/CustomControls/ScriptConsole.cs

@@ -1,6 +1,5 @@
 using Robust.Client.Graphics;
 using Robust.Client.UserInterface.Controls;
-using Robust.Shared.Localization;
 using Robust.Shared.Maths;
 
 namespace Robust.Client.UserInterface.CustomControls
@@ -37,9 +36,9 @@ namespace Robust.Client.UserInterface.CustomControls
                             (InputBar = new HistoryLineEdit
                             {
                                 HorizontalExpand = true,
-                                PlaceHolder = Loc.GetString("Your C# code here.")
+                                PlaceHolder = "Your C# code here."
                             }),
-                            (RunButton = new Button {Text = Loc.GetString("Run")})
+                            (RunButton = new Button {Text = "Run"})
                         }
                     },
                 }

Robust.Client/UserInterface/FileDialogManager.cs

@@ -148,7 +148,7 @@ namespace Robust.Client.UserInterface
         // ReSharper disable once MemberCanBeMadeStatic.Local
         private Task<string?> RunAsyncMaybe(Func<string?> action)
         {
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            if (OperatingSystem.IsMacOS())
             {
                 // macOS seems pretty annoying about having the file dialog opened from the main thread.
                 // So we are forced to execute this synchronously on the main thread.
@@ -326,7 +326,7 @@ namespace Robust.Client.UserInterface
 
         private async Task<bool> IsKDialogAvailable()
         {
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+            if (!OperatingSystem.IsLinux())
                 return false;
 
             if (!_checkedKDialogAvailable)

Robust.Client/ViewVariables/Instances/ViewVariablesInstanceEntity.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
@@ -120,7 +120,7 @@ namespace Robust.Client.ViewVariables.Instances
 
             var clientVBox = new VBoxContainer {SeparationOverride = 0};
             _tabs.AddChild(clientVBox);
-            _tabs.SetTabTitle(TabClientVars, "Client Variables");
+            _tabs.SetTabTitle(TabClientVars, Loc.GetString("view-variable-instance-entity-client-variables-tab-title"));
 
             var first = true;
             foreach (var group in LocalPropertyList(obj, ViewVariablesManager, _robustSerializer))
@@ -138,7 +138,7 @@ namespace Robust.Client.ViewVariables.Instances
 
             _clientComponents = new VBoxContainer {SeparationOverride = 0};
             _tabs.AddChild(_clientComponents);
-            _tabs.SetTabTitle(TabClientComponents, "Client Components");
+            _tabs.SetTabTitle(TabClientComponents, Loc.GetString("view-variable-instance-entity-client-components-tab-title"));
 
             PopulateClientComponents();
 
@@ -146,11 +146,11 @@ namespace Robust.Client.ViewVariables.Instances
             {
                 _serverVariables = new VBoxContainer {SeparationOverride = 0};
                 _tabs.AddChild(_serverVariables);
-                _tabs.SetTabTitle(TabServerVars, "Server Variables");
+                _tabs.SetTabTitle(TabServerVars, Loc.GetString("view-variable-instance-entity-server-variables-tab-title"));
 
                 _serverComponents = new VBoxContainer {SeparationOverride = 0};
                 _tabs.AddChild(_serverComponents);
-                _tabs.SetTabTitle(TabServerComponents, "Server Components");
+                _tabs.SetTabTitle(TabServerComponents, Loc.GetString("view-variable-instance-entity-server-components-tab-title"));
 
                 PopulateServerComponents(false);
             }
@@ -162,13 +162,13 @@ namespace Robust.Client.ViewVariables.Instances
 
             _clientComponents.AddChild(_clientComponentsSearchBar = new LineEdit
             {
-                PlaceHolder = Loc.GetString("Search"),
+                PlaceHolder = Loc.GetString("view-variable-instance-entity-client-components-search-bar-placeholder"),
                 HorizontalExpand = true,
             });
 
             _clientComponents.AddChild(_clientComponentsAddButton = new Button()
             {
-                Text = Loc.GetString("Add Component"),
+                Text = Loc.GetString("view-variable-instance-entity-server-components-add-component-button-placeholder"),
                 HorizontalExpand = true,
             });
 
@@ -198,13 +198,13 @@ namespace Robust.Client.ViewVariables.Instances
 
             _serverComponents.AddChild(_serverComponentsSearchBar = new LineEdit
             {
-                PlaceHolder = Loc.GetString("Search"),
+                PlaceHolder = Loc.GetString("view-variable-instance-entity-server-components-search-bar-placeholder"),
                 HorizontalExpand = true,
             });
 
             _serverComponents.AddChild(_serverComponentsAddButton = new Button()
             {
-                Text = Loc.GetString("Add Component"),
+                Text = Loc.GetString("view-variable-instance-entity-server-components-add-component-button-placeholder"),
                 HorizontalExpand = true,
             });
 
@@ -336,7 +336,7 @@ namespace Robust.Client.ViewVariables.Instances
         {
             _addComponentWindow?.Dispose();
 
-            _addComponentWindow = new ViewVariablesAddWindow(GetValidComponentsForAdding(), "Add Component [C]");
+            _addComponentWindow = new ViewVariablesAddWindow(GetValidComponentsForAdding(), Loc.GetString("view-variable-instance-entity-add-window-client-components"));
             _addComponentWindow.AddButtonPressed += TryAdd;
             _addComponentServer = false;
 
@@ -349,7 +349,7 @@ namespace Robust.Client.ViewVariables.Instances
 
             if (_entitySession == null) return;
 
-            _addComponentWindow = new ViewVariablesAddWindow(await GetValidServerComponentsForAdding(), "Add Component [S]");
+            _addComponentWindow = new ViewVariablesAddWindow(await GetValidServerComponentsForAdding(), Loc.GetString("view-variable-instance-entity-add-window-server-components"));
             _addComponentWindow.AddButtonPressed += TryAdd;
             _addComponentServer = true;
 

Robust.Server/BaseServer.cs

@@ -237,6 +237,8 @@ namespace Robust.Server
                 }
             }
 
+            ProgramShared.PrintRuntimeInfo(_log.RootSawmill);
+
             SelfLog.Enable(s => { System.Console.WriteLine("SERILOG ERROR: {0}", s); });
 
             if (!SetupLoki())
@@ -353,7 +355,7 @@ namespace Robust.Server
             AddFinalStringsToSerializer();
             _stringSerializer.LockStrings();
 
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && _config.GetCVar(CVars.SysWinTickPeriod) >= 0)
+            if (OperatingSystem.IsWindows() && _config.GetCVar(CVars.SysWinTickPeriod) >= 0)
             {
                 WindowsTickPeriod.TimeBeginPeriod((uint) _config.GetCVar(CVars.SysWinTickPeriod));
             }
@@ -371,6 +373,19 @@ namespace Robust.Server
                 var reg = factory.GetRegistration(regType);
                 _stringSerializer.AddString(reg.Name);
             }
+
+            using var extraMappedStrings = typeof(BaseServer).Assembly
+                .GetManifestResourceStream("Robust.Server.ExtraMappedSerializerStrings.txt");
+
+            if (extraMappedStrings != null)
+            {
+                using var sr = new StreamReader(extraMappedStrings);
+                string? line;
+                while ((line = sr.ReadLine()) != null)
+                {
+                    _stringSerializer.AddString(line);
+                }
+            }
         }
 
         private bool SetupLoki()
@@ -434,8 +449,7 @@ namespace Robust.Server
             }
         }
 
-        /// <inheritdoc />
-        public void MainLoop()
+        internal void SetupMainLoop()
         {
             if (_mainLoop == null)
             {
@@ -457,14 +471,26 @@ namespace Robust.Server
 
             // set GameLoop.Running to false to return from this function.
             _time.Paused = false;
-            _mainLoop.Run();
+        }
 
+        internal void FinishMainLoop()
+        {
             _time.InSimulation = true;
             Cleanup();
 
             _shutdownEvent.Set();
         }
 
+        /// <inheritdoc />
+        public void MainLoop()
+        {
+            SetupMainLoop();
+
+            _mainLoop.Run();
+
+            FinishMainLoop();
+        }
+
         public bool ContentStart { get; set; }
         public bool LoadConfigAndUserData { private get; set; } = true;
 
@@ -545,7 +571,7 @@ namespace Robust.Server
 
             //TODO: This should prob shutdown all managers in a loop.
 
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && _config.GetCVar(CVars.SysWinTickPeriod) >= 0)
+            if (OperatingSystem.IsWindows() && _config.GetCVar(CVars.SysWinTickPeriod) >= 0)
             {
                 WindowsTickPeriod.TimeEndPeriod((uint) _config.GetCVar(CVars.SysWinTickPeriod));
             }

Robust.Server/ExtraMappedSerializerStrings.txt

@@ -0,0 +1 @@
+fixture-0

Robust.Server/GameObjects/Components/Actor/ActorComponent.cs

@@ -1,4 +1,3 @@
-using System;
 using Robust.Server.Player;
 using Robust.Shared.GameObjects;
 using Robust.Shared.ViewVariables;
@@ -12,34 +11,4 @@ namespace Robust.Server.GameObjects
         [ViewVariables]
         public IPlayerSession PlayerSession { get; internal set; } = default!;
     }
-
-    /// <summary>
-    ///     Raised on an entity whenever a player attaches to this entity.
-    /// </summary>
-    [Serializable]
-    [Obsolete("Component Messages are deprecated, use Entity Events instead.")]
-    public class PlayerAttachedMsg : ComponentMessage
-    {
-        public IPlayerSession NewPlayer { get; }
-
-        public PlayerAttachedMsg(IPlayerSession newPlayer)
-        {
-            NewPlayer = newPlayer;
-        }
-    }
-
-    /// <summary>
-    ///     Raised on an entity whenever a player detaches from this entity.
-    /// </summary>
-    [Serializable]
-    [Obsolete("Component Messages are deprecated, use Entity Events instead.")]
-    public class PlayerDetachedMsg : ComponentMessage
-    {
-        public IPlayerSession OldPlayer { get; }
-
-        public PlayerDetachedMsg(IPlayerSession oldPlayer)
-        {
-            OldPlayer = oldPlayer;
-        }
-    }
 }

Robust.Server/GameObjects/EntitySystems/ActorSystem.cs

@@ -1,4 +1,3 @@
-using System;
 using JetBrains.Annotations;
 using Robust.Server.Player;
 using Robust.Shared.GameObjects;
@@ -9,7 +8,7 @@ namespace Robust.Server.GameObjects
     ///     System that handles players being attached/detached from entities.
     /// </summary>
     [UsedImplicitly]
-    public class ActorSystem : EntitySystem
+    public sealed class ActorSystem : EntitySystem
     {
         public override void Initialize()
         {
@@ -22,27 +21,54 @@ namespace Robust.Server.GameObjects
 
         private void OnActorPlayerAttach(AttachPlayerEvent args)
         {
+            args.Result = Attach(args.Entity, args.Player, args.Force, out var forceKicked);
+            args.ForceKicked = forceKicked;
+        }
+
+        /// <summary>
+        ///     Attaches a player session to an entity, optionally kicking any sessions already attached to it.
+        /// </summary>
+        /// <param name="entity">The entity to attach the player to</param>
+        /// <param name="player">The player to attach to the entity</param>
+        /// <param name="force">Whether to kick any existing players from the entity</param>
+        /// <returns>Whether the attach succeeded, or not.</returns>
+        public bool Attach(IEntity entity, IPlayerSession player, bool force = false)
+        {
+            return Attach(entity, player, false, out _);
+        }
+
+        /// <summary>
+        ///     Attaches a player session to an entity, optionally kicking any sessions already attached to it.
+        /// </summary>
+        /// <param name="entity">The entity to attach the player to</param>
+        /// <param name="player">The player to attach to the entity</param>
+        /// <param name="force">Whether to kick any existing players from the entity</param>
+        /// <param name="forceKicked">The player that was forcefully kicked, or null.</param>
+        /// <returns>Whether the attach succeeded, or not.</returns>
+        public bool Attach(IEntity entity, IPlayerSession player, bool force, out IPlayerSession? forceKicked)
+        {
+            // Null by default.
+            forceKicked = null;
+
             // Cannot attach to a deleted entity.
-            if (args.Entity.Deleted)
+            if (entity.Deleted)
             {
-                args.Result = false;
-                return;
+                return false;
             }
 
-            var uid = args.Entity.Uid;
+            var uid = entity.Uid;
 
             // Check if there was a player attached to the entity already...
             if (ComponentManager.TryGetComponent(uid, out ActorComponent actor))
             {
                 // If we're not forcing the attach, this fails.
-                if (!args.Force)
+                if (!force)
                 {
-                    args.Result = false;
-                    return;
+                    return false;
                 }
 
                 // Set the event's force-kicked session before detaching it.
-                args.ForceKicked = actor.PlayerSession;
+                forceKicked = actor.PlayerSession;
 
                 // This detach cannot fail, as a player is attached to this entity.
                 // It's important to note that detaching the player removes the component.
@@ -50,18 +76,16 @@ namespace Robust.Server.GameObjects
             }
 
             // We add the actor component.
-            actor = ComponentManager.AddComponent<ActorComponent>(args.Entity);
-            actor.PlayerSession = args.Player;
-            args.Player.SetAttachedEntity(args.Entity);
-            args.Result = true;
-
-            // TODO: Remove component message.
-            args.Entity.SendMessage(actor, new PlayerAttachedMsg(args.Player));
+            actor = ComponentManager.AddComponent<ActorComponent>(entity);
+            actor.PlayerSession = player;
+            player.SetAttachedEntity(entity);
 
             // The player is fully attached now, raise an event!
-            RaiseLocalEvent(uid, new PlayerAttachedEvent(args.Entity, args.Player));
+            RaiseLocalEvent(uid, new PlayerAttachedEvent(entity, player, forceKicked));
+            return true;
         }
 
+        // Not gonna make this method call Detach as all we have to do is remove a component...
         private void OnActorPlayerDetach(EntityUid uid, ActorComponent component, DetachPlayerEvent args)
         {
             // Removing the component will call shutdown, and our subscription will handle the rest of the detach logic.
@@ -69,15 +93,39 @@ namespace Robust.Server.GameObjects
             args.Result = true;
         }
 
+        /// <summary>
+        ///     Detaches an attached session from the entity, if any.
+        /// </summary>
+        /// <param name="entity">The entity player sessions will be detached from.</param>
+        /// <returns>Whether any player session was detached.</returns>
+        public bool Detach(IEntity entity)
+        {
+            if (!entity.HasComponent<ActorComponent>())
+                return false;
+
+            // Removing the component will call shutdown, and our subscription will handle the rest of the detach logic.
+            entity.RemoveComponent<ActorComponent>();
+            return true;
+        }
+
+        /// <summary>
+        ///     Detaches this player from its attached entity, if any.
+        /// </summary>
+        /// <param name="player">The player session that will be detached from any attached entities.</param>
+        /// <returns>Whether the player is now detached from any entities.
+        /// This returns true if the player wasn't attached to any entity.</returns>
+        public bool Detach(IPlayerSession player)
+        {
+            var entity = player.AttachedEntity;
+            return entity == null || Detach(entity);
+        }
+
         private void OnActorShutdown(EntityUid uid, ActorComponent component, ComponentShutdown args)
         {
             component.PlayerSession.SetAttachedEntity(null);
 
             var entity = EntityManager.GetEntity(uid);
 
-            // TODO: Remove component message.
-            entity.SendMessage(component, new PlayerDetachedMsg(component.PlayerSession));
-
             // The player is fully detached now that the component has shut down.
             RaiseLocalEvent(uid, new PlayerDetachedEvent(entity, component.PlayerSession));
         }
@@ -86,7 +134,7 @@ namespace Robust.Server.GameObjects
     /// <summary>
     ///     Raise this broadcast event to attach a player to an entity, optionally detaching the player attached to it.
     /// </summary>
-    public class AttachPlayerEvent : EntityEventArgs
+    public sealed class AttachPlayerEvent : EntityEventArgs
     {
         /// <summary>
         ///     Player to attach to the entity.
@@ -131,7 +179,7 @@ namespace Robust.Server.GameObjects
     /// <summary>
     ///     Raise this directed event to detach a player from an entity.
     /// </summary>
-    public class DetachPlayerEvent : EntityEventArgs
+    public sealed class DetachPlayerEvent : EntityEventArgs
     {
         /// <summary>
         ///     Whether the player was detached correctly.
@@ -144,22 +192,28 @@ namespace Robust.Server.GameObjects
     /// <summary>
     ///     Event for when a player has been attached to an entity.
     /// </summary>
-    public class PlayerAttachedEvent : EntityEventArgs
+    public sealed class PlayerAttachedEvent : EntityEventArgs
     {
         public IEntity Entity { get; }
         public IPlayerSession Player { get; }
 
-        public PlayerAttachedEvent(IEntity entity, IPlayerSession player)
+        /// <summary>
+        ///     The player session that was forcefully kicked from the entity, if any.
+        /// </summary>
+        public IPlayerSession? Kicked { get; }
+
+        public PlayerAttachedEvent(IEntity entity, IPlayerSession player, IPlayerSession? kicked = null)
         {
             Entity = entity;
             Player = player;
+            Kicked = kicked;
         }
     }
 
     /// <summary>
     ///     Event for when a player has been detached from an entity.
     /// </summary>
-    public class PlayerDetachedEvent : EntityEventArgs
+    public sealed class PlayerDetachedEvent : EntityEventArgs
     {
         public IEntity Entity { get; }
         public IPlayerSession Player { get; }

Robust.Server/GameObjects/EntitySystems/TileLookup/GridTileLookupNode.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using Robust.Shared.Containers;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Maths;
 
@@ -7,7 +8,7 @@ namespace Robust.Server.GameObjects
     internal sealed class GridTileLookupNode
     {
         internal GridTileLookupChunk ParentChunk { get; }
-        
+
         internal Vector2i Indices { get; }
 
         internal IEnumerable<IEntity> Entities
@@ -17,7 +18,18 @@ namespace Robust.Server.GameObjects
                 foreach (var entity in _entities)
                 {
                     if (!entity.Deleted)
+                    {
                         yield return entity;
+                    }
+
+                    if (!entity.TryGetComponent(out ContainerManagerComponent? containerManager)) continue;
+                    foreach (var container in containerManager.GetAllContainers())
+                    {
+                        foreach (var child in container.ContainedEntities)
+                        {
+                            yield return child;
+                        }
+                    }
                 }
             }
         }
@@ -29,7 +41,7 @@ namespace Robust.Server.GameObjects
             ParentChunk = parentChunk;
             Indices = indices;
         }
-        
+
         internal void AddEntity(IEntity entity)
         {
             _entities.Add(entity);

Robust.Server/GameObjects/EntitySystems/TileLookup/GridTileLookupSystem.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using JetBrains.Annotations;
+using Robust.Shared.Containers;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
@@ -200,16 +201,20 @@ namespace Robust.Server.GameObjects
         private Box2 GetEntityBox(IEntity entity)
         {
             var aabb = _lookup.GetWorldAabbFromEntity(entity);
-            return aabb.IsEmpty() ? aabb : aabb.Enlarged(-0.1f);
+
+            // Need to clip the aabb as anything with an edge intersecting another tile might be picked up, such as walls.
+            return aabb.Scale(0.98f);
         }
 
         public override void Initialize()
         {
             base.Initialize();
-#if DEBUG
+            #if DEBUG
             SubscribeNetworkEvent<RequestGridTileLookupMessage>(HandleRequest);
-#endif
+            #endif
             SubscribeLocalEvent<MoveEvent>(HandleEntityMove);
+            SubscribeLocalEvent<EntInsertedIntoContainerMessage>(HandleContainerInsert);
+            SubscribeLocalEvent<EntRemovedFromContainerMessage>(HandleContainerRemove);
             SubscribeLocalEvent<EntityInitializedMessage>(HandleEntityInitialized);
             SubscribeLocalEvent<EntityDeletedMessage>(HandleEntityDeleted);
             _mapManager.OnGridCreated += HandleGridCreated;
@@ -217,6 +222,16 @@ namespace Robust.Server.GameObjects
             _mapManager.TileChanged += HandleTileChanged;
         }
 
+        private void HandleContainerRemove(EntRemovedFromContainerMessage ev)
+        {
+            HandleEntityAdd(ev.Entity);
+        }
+
+        private void HandleContainerInsert(EntInsertedIntoContainerMessage ev)
+        {
+            HandleEntityRemove(ev.Entity);
+        }
+
         public override void Shutdown()
         {
             base.Shutdown();
@@ -236,6 +251,11 @@ namespace Robust.Server.GameObjects
 
         private void HandleEntityInitialized(EntityInitializedMessage message)
         {
+            if (message.Entity.IsInContainer())
+            {
+                return;
+            }
+
             HandleEntityAdd(message.Entity);
         }
 

Robust.Server/GameObjects/ServerEntityManager.cs

@@ -232,6 +232,7 @@ namespace Robust.Server.GameObjects
                     var msg = message.SystemMessage;
                     var sessionType = typeof(EntitySessionMessage<>).MakeGenericType(msg.GetType());
                     var sessionMsg = Activator.CreateInstance(sessionType, new EntitySessionEventArgs(player), msg)!;
+                    ReceivedSystemMessage?.Invoke(this, msg);
                     ReceivedSystemMessage?.Invoke(this, sessionMsg);
                     return;
             }

Robust.Server/GameStates/EntityViewCulling.cs

@@ -213,7 +213,8 @@ namespace Robust.Server.GameStates
                         new TransformComponent.TransformComponentState(Vector2NaN,
                             oldState.Rotation,
                             oldState.ParentID,
-                            oldState.NoLocalRotation)
+                            oldState.NoLocalRotation,
+                            oldState.Anchored)
                     }));
             }
 

Robust.Server/GameStates/ServerGameStateManager.cs

@@ -183,6 +183,8 @@ namespace Robust.Server.GameStates
                     oldestAck = lastAck;
                 }
 
+                DebugTools.Assert(state.MapData?.CreatedMaps is null || (state.MapData?.CreatedMaps is not null && state.EntityStates is not null), "Sending new maps, but no entity state.");
+
                 // actually send the state
                 var stateUpdateMessage = _networkManager.CreateNetMessage<MsgState>();
                 stateUpdateMessage.State = state;
@@ -296,10 +298,8 @@ namespace Robust.Server.GameStates
 
                 DebugTools.Assert(entity.Initialized);
 
-                if (entity.LastModifiedTick <= fromTick)
-                    continue;
-
-                stateEntities.Add(GetEntityState(entityMan.ComponentManager, player, entity.Uid, fromTick));
+                if (entity.LastModifiedTick >= fromTick)
+                    stateEntities.Add(GetEntityState(entityMan.ComponentManager, player, entity.Uid, fromTick));
             }
 
             // no point sending an empty collection

Robust.Server/Player/PlayerSession.cs

@@ -117,11 +117,7 @@ namespace Robust.Server.Player
             if (entity == null)
                 return;
 
-            // This event needs to be broadcast.
-            var attachPlayer = new AttachPlayerEvent(entity, this);
-            entity.EntityManager.EventBus.RaiseLocalEvent(entity.Uid, attachPlayer);
-
-            if (!attachPlayer.Result)
+            if (!EntitySystem.Get<ActorSystem>().Attach(entity, this))
             {
                 Logger.Warning($"Couldn't attach player \"{this}\" to entity \"{entity}\"! Did it have a player already attached to it?");
             }
@@ -133,10 +129,19 @@ namespace Robust.Server.Player
             if (AttachedEntity == null)
                 return;
 
-            var detachPlayer = new DetachPlayerEvent();
-            AttachedEntity.EntityManager.EventBus.RaiseLocalEvent(AttachedEntity.Uid, detachPlayer, false);
+#if EXCEPTION_TOLERANCE
+            if (AttachedEntity.Deleted)
+            {
+                Logger.Warning($"Player \"{this}\" was attached to an entity that was deleted. THIS SHOULD NEVER HAPPEN, BUT DOES.");
+                // We can't contact ActorSystem because trying to fire an entity event would crash.
+                // Work around it.
+                AttachedEntity = null;
+                UpdatePlayerState();
+                return;
+            }
+#endif
 
-            if (!detachPlayer.Result)
+            if (!EntitySystem.Get<ActorSystem>().Detach(AttachedEntity))
             {
                 Logger.Warning($"Couldn't detach player \"{this}\" to entity \"{AttachedEntity}\"! Is it missing an ActorComponent?");
             }

Robust.Server/Program.cs

@@ -98,7 +98,7 @@ namespace Robust.Server
 
         internal static void SetupLogging()
         {
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (OperatingSystem.IsWindows())
             {
 #if WINDOWS_USE_UTF8_CONSOLE
                 System.Console.OutputEncoding = Encoding.UTF8;

Robust.Server/Robust.Server.csproj

@@ -29,6 +29,9 @@
     <Content Include="server_config.toml">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <EmbeddedResource Include="ExtraMappedSerializerStrings.txt">
+      <LogicalName>Robust.Server.ExtraMappedSerializerStrings.txt</LogicalName>
+    </EmbeddedResource>
   </ItemGroup>
   <Import Project="..\MSBuild\Robust.Engine.targets" />
 </Project>

Robust.Server/ServerIoC.cs

@@ -37,6 +37,7 @@ namespace Robust.Server
 
             IoCManager.Register<IBaseServer, BaseServer>();
             IoCManager.Register<IBaseServerInternal, BaseServer>();
+            IoCManager.Register<BaseServer, BaseServer>();
             IoCManager.Register<IGameTiming, GameTiming>();
             IoCManager.Register<IComponentFactory, ServerComponentFactory>();
             IoCManager.Register<IConGroupController, ConGroupController>();

Robust.Server/Utility/WindowsTickPeriod.cs

@@ -11,7 +11,7 @@ namespace Robust.Server.Utility
 
         public static void TimeBeginPeriod(uint period)
         {
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!OperatingSystem.IsWindows())
                 throw new InvalidOperationException();
 
             var ret = timeBeginPeriod(period);
@@ -21,7 +21,7 @@ namespace Robust.Server.Utility
 
         public static void TimeEndPeriod(uint period)
         {
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!OperatingSystem.IsWindows())
                 throw new InvalidOperationException();
 
             var ret = timeEndPeriod(period);

Robust.Shared.Maths/FloatMath.cs

@@ -1,45 +0,0 @@
-using System;
-using System.Runtime.CompilerServices;
-
-namespace Robust.Shared.Maths
-{
-    [Obsolete("Use MathHelper instead.")]
-    public static class FloatMath
-    {
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static float Clamp01(float val)
-        {
-            return MathHelper.Clamp01(val);
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static T Clamp<T>(T val, T min, T max) where T : IComparable<T>
-        {
-            return MathHelper.Clamp(val, min, max);
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static float Clamp(float val, float min, float max)
-        {
-            return MathHelper.Clamp(val, min, max);
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static double Clamp(double val, double min, double max)
-        {
-            return MathHelper.Clamp(val, min, max);
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static bool CloseTo(float a, float b, double tolerance = .00001)
-        {
-            return MathHelper.CloseTo(a, b, tolerance);
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static float Lerp(float a, float b, float blend)
-        {
-            return MathHelper.Lerp(a, b, blend);
-        }
-    }
-}

Robust.Shared/Asynchronous/TaskManager.cs

@@ -14,6 +14,11 @@ namespace Robust.Shared.Asynchronous
         public void Initialize()
         {
             _mainThreadContext = new RobustSynchronizationContext(_runtimeLog);
+            ResetSynchronizationContext();
+        }
+
+        public void ResetSynchronizationContext()
+        {
             SynchronizationContext.SetSynchronizationContext(_mainThreadContext);
         }
 

Robust.Shared/CVars.cs

@@ -73,7 +73,7 @@ namespace Robust.Shared
         // just has the Lidgren thread go absolute brr polling.
         public static readonly CVarDef<float> NetPredictLagBias = CVarDef.Create(
                 "net.predict_lag_bias",
-                RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? 0.016f : 0,
+                OperatingSystem.IsWindows() ? 0.016f : 0,
                 CVar.ARCHIVE);
 
         public static readonly CVarDef<int> NetStateBufMergeThreshold =
@@ -211,6 +211,21 @@ namespace Robust.Shared
         public static readonly CVarDef<bool> LogRuntimeLog =
             CVarDef.Create("log.runtimelog", true, CVar.ARCHIVE | CVar.SERVERONLY);
 
+        /*
+         * Light
+         */
+
+        /// <summary>
+        /// This is the maximum the viewport is enlarged to check for any intersecting render-trees for lights.
+        /// This should be set to your maximum light radius.
+        /// </summary>
+        /// <remarks>
+        /// If this value is too small it just means there may be pop-in where a light is located on a render-tree
+        /// outside of our viewport.
+        /// </remarks>
+        public static readonly CVarDef<float> MaxLightRadius =
+            CVarDef.Create("light.max_radius", 20.0f, CVar.CLIENTONLY);
+
         /*
          * LOKI
          */

Robust.Shared/Containers/BaseContainer.cs

@@ -68,6 +68,10 @@ namespace Robust.Shared.Containers
             InternalInsert(toinsert);
             transform.AttachParent(Owner.Transform);
 
+            // This is an edge case where the parent grid is the container being inserted into, so AttachParent would not unanchor.
+            if (transform.Anchored)
+                transform.Anchored = false;
+
             // spatially move the object to the location of the container. If you don't want this functionality, the
             // calling code can save the local position before calling this function, and apply it afterwords.
             transform.LocalPosition = Vector2.Zero;
@@ -145,9 +149,8 @@ namespace Robust.Shared.Containers
         {
             DebugTools.Assert(!Deleted);
 
-            Owner.EntityManager.EventBus.RaiseEvent(EventSource.Local, new EntInsertedIntoContainerMessage(toinsert, this));
+            Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new EntInsertedIntoContainerMessage(toinsert, this));
             Owner.EntityManager.EventBus.RaiseEvent(EventSource.Local, new UpdateContainerOcclusionMessage(toinsert));
-            Manager.Owner.SendMessage(Manager, new ContainerContentsModifiedMessage(this, toinsert, false));
             Manager.Dirty();
         }
 
@@ -162,9 +165,8 @@ namespace Robust.Shared.Containers
             DebugTools.AssertNotNull(toremove);
             DebugTools.Assert(toremove.IsValid());
 
-            Owner.EntityManager.EventBus.RaiseEvent(EventSource.Local, new EntRemovedFromContainerMessage(toremove, this));
+            Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new EntRemovedFromContainerMessage(toremove, this));
             Owner.EntityManager.EventBus.RaiseEvent(EventSource.Local, new UpdateContainerOcclusionMessage(toremove));
-            Manager.Owner.SendMessage(Manager, new ContainerContentsModifiedMessage(this, toremove, true));
             Manager.Dirty();
         }
     }

Robust.Shared/Containers/ContainerContentsModifiedMessage.cs

@@ -1,40 +0,0 @@
-using System;
-using Robust.Shared.GameObjects;
-
-namespace Robust.Shared.Containers
-{
-    /// <summary>
-    /// The contents of this container have been changed.
-    /// </summary>
-    [Obsolete("Component Messages are deprecated, use Entity Events instead.")]
-    public class ContainerContentsModifiedMessage : ComponentMessage
-    {
-        /// <summary>
-        /// Container whose contents were modified.
-        /// </summary>
-        public IContainer Container { get; }
-
-        /// <summary>
-        /// Entity that was added or removed from the container.
-        /// </summary>
-        public IEntity Entity { get; }
-
-        /// <summary>
-        /// If true, the entity was removed. If false, it was added to the container.
-        /// </summary>
-        public bool Removed { get; }
-
-        /// <summary>
-        /// Constructs a new instance of <see cref="ContainerContentsModifiedMessage"/>.
-        /// </summary>
-        /// <param name="container">Container whose contents were modified.</param>
-        /// <param name="entity">Entity that was added or removed in the container.</param>
-        /// <param name="removed">If true, the entity was removed. If false, it was added to the container.</param>
-        public ContainerContentsModifiedMessage(IContainer container, IEntity entity, bool removed)
-        {
-            Container = container;
-            Entity = entity;
-            Removed = removed;
-        }
-    }
-}

Robust.Shared/Containers/ContainerManagerComponent.cs

@@ -33,7 +33,7 @@ namespace Robust.Shared.Containers
         public sealed override uint? NetID => NetIDs.CONTAINER_MANAGER;
 
         /// <inheritdoc />
-        public override void OnRemove()
+        protected override void OnRemove()
         {
             base.OnRemove();
 
@@ -47,7 +47,7 @@ namespace Robust.Shared.Containers
         }
 
         /// <inheritdoc />
-        public override void Initialize()
+        protected override void Initialize()
         {
             base.Initialize();
 

Robust.Shared/ContentPack/ModLoader.cs

@@ -106,8 +106,16 @@ namespace Robust.Shared.ContentPack
                 Logger.DebugS("res.mod", $"Verified assemblies in {checkerSw.ElapsedMilliseconds}ms");
             }
 
+            var nodes = TopologicalSort.FromBeforeAfter(
+                files,
+                kv => kv.Key,
+                kv => kv.Value.Path,
+                _ => Array.Empty<string>(),
+                kv => kv.Value.references,
+                allowMissing: true); // missing refs would be non-content assemblies so allow that.
+
             // Actually load them in the order they depend on each other.
-            foreach (var path in TopologicalSortModules(files))
+            foreach (var path in TopologicalSort.Sort(nodes))
             {
                 Logger.DebugS("res.mod", $"Loading module: '{path}'");
                 try
@@ -136,38 +144,6 @@ namespace Robust.Shared.ContentPack
             return true;
         }
 
-        private static IEnumerable<ResourcePath> TopologicalSortModules(
-            IEnumerable<KeyValuePair<string, (ResourcePath Path, string[] references)>> modules)
-        {
-            var elems = modules.ToDictionary(
-                node => node.Key,
-                node => (node.Value.Path, refs: new HashSet<string>(node.Value.references)));
-
-            // Remove assembly references we aren't sorting for.
-            foreach (var (_, set) in elems.Values)
-            {
-                set.RemoveWhere(r => !elems.ContainsKey(r));
-            }
-
-            while (elems.Count > 0)
-            {
-                var elem = elems.FirstOrNull(x => x.Value.refs.Count == 0);
-                if (elem == null)
-                {
-                    throw new InvalidOperationException(
-                        "Found circular dependency in assembly dependency graph");
-                }
-
-                elems.Remove(elem.Value.Key);
-                foreach (var sElem in elems)
-                {
-                    sElem.Value.refs.Remove(elem.Value.Key);
-                }
-
-                yield return elem.Value.Value.Path;
-            }
-        }
-
         private static (string[] refs, string name) GetAssemblyReferenceData(Stream stream)
         {
             using var reader = new PEReader(stream);

Robust.Shared/ContentPack/PathHelpers.cs

@@ -60,8 +60,8 @@ namespace Robust.Shared.ContentPack
 
         // TODO: gaf
         public static bool IsFileSystemCaseSensitive() =>
-            !RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
-            && !RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
+            !OperatingSystem.IsWindows()
+            && !OperatingSystem.IsMacOS();
 
     }
 }

Robust.Shared/DllMapHelper.cs

@@ -33,12 +33,12 @@ namespace Robust.Shared
                     return IntPtr.Zero;
                 }
 
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+                if (OperatingSystem.IsLinux())
                 {
                     return NativeLibrary.Load(linuxName, assembly, path);
                 }
 
-                if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+                if (OperatingSystem.IsMacOS())
                 {
                     return NativeLibrary.Load(macName, assembly, path);
                 }

Robust.Shared/GameObjects/Component.cs

@@ -41,31 +41,94 @@ namespace Robust.Shared.GameObjects
 
         /// <inheritdoc />
         [ViewVariables]
-        public bool Initialized { get; private set; }
+        public ComponentLifeStage LifeStage { get; private set; } = ComponentLifeStage.PreAdd;
 
-        private bool _running;
-        /// <inheritdoc />
-        [ViewVariables(VVAccess.ReadWrite)]
-        public bool Running
+        /// <summary>
+        /// Increases the life stage from <see cref="ComponentLifeStage.PreAdd" /> to <see cref="ComponentLifeStage.Added" />,
+        /// calling <see cref="OnAdd" />.
+        /// </summary>
+        internal void LifeAddToEntity()
         {
-            get => _running;
-            set
-            {
-                if(_running == value)
-                    return;
+            DebugTools.Assert(LifeStage == ComponentLifeStage.PreAdd);
 
-                if(value)
-                    Startup();
-                else
-                    Shutdown();
+            LifeStage = ComponentLifeStage.Adding;
+            OnAdd();
 
-                _running = value;
-            }
+            DebugTools.Assert(LifeStage == ComponentLifeStage.Added, $"Component {this.GetType().Name} did not call base {nameof(OnAdd)} in derived method.");
+        }
+
+        /// <summary>
+        /// Increases the life stage from <see cref="ComponentLifeStage.Added" /> to <see cref="ComponentLifeStage.Initialized" />,
+        /// calling <see cref="Initialize" />.
+        /// </summary>
+        internal void LifeInitialize()
+        {
+            DebugTools.Assert(LifeStage == ComponentLifeStage.Added);
+
+            LifeStage = ComponentLifeStage.Initializing;
+            Initialize();
+
+            DebugTools.Assert(LifeStage == ComponentLifeStage.Initialized, $"Component {this.GetType().Name} did not call base {nameof(Initialize)} in derived method.");
+        }
+
+        /// <summary>
+        /// Increases the life stage from <see cref="ComponentLifeStage.Initialized" /> to
+        /// <see cref="ComponentLifeStage.Running" />, calling <see cref="Startup" />.
+        /// </summary>
+        internal void LifeStartup()
+        {
+            DebugTools.Assert(LifeStage == ComponentLifeStage.Initialized);
+
+            LifeStage = ComponentLifeStage.Starting;
+            Startup();
+
+            DebugTools.Assert(LifeStage == ComponentLifeStage.Running, $"Component {this.GetType().Name} did not call base {nameof(Startup)} in derived method.");
+        }
+
+        /// <summary>
+        /// Increases the life stage from <see cref="ComponentLifeStage.Running" /> to <see cref="ComponentLifeStage.Stopped" />,
+        /// calling <see cref="Shutdown" />.
+        /// </summary>
+        /// <remarks>
+        /// Components are allowed to remove themselves in their own Startup function.
+        /// </remarks>
+        internal void LifeShutdown()
+        {
+            // Starting allows a component to remove itself in it's own Startup function.
+            DebugTools.Assert(LifeStage == ComponentLifeStage.Starting || LifeStage == ComponentLifeStage.Running);
+
+            LifeStage = ComponentLifeStage.Stopping;
+            Shutdown();
+
+            DebugTools.Assert(LifeStage == ComponentLifeStage.Stopped, $"Component {this.GetType().Name} did not call base {nameof(Shutdown)} in derived method.");
+        }
+
+        /// <summary>
+        /// Increases the life stage from <see cref="ComponentLifeStage.Stopped" /> to <see cref="ComponentLifeStage.Deleted" />,
+        /// calling <see cref="OnRemove" />.
+        /// </summary>
+        internal void LifeRemoveFromEntity()
+        {
+            // can be called at any time after PreAdd, including inside other life stage events.
+            DebugTools.Assert(LifeStage != ComponentLifeStage.PreAdd);
+
+            LifeStage = ComponentLifeStage.Removing;
+            OnRemove();
+
+            DebugTools.Assert(LifeStage == ComponentLifeStage.Deleted, $"Component {this.GetType().Name} did not call base {nameof(OnRemove)} in derived method.");
         }
 
         /// <inheritdoc />
         [ViewVariables]
-        public bool Deleted { get; private set; }
+        public bool Initialized => LifeStage >= ComponentLifeStage.Initializing;
+
+        /// <inheritdoc />
+        [ViewVariables]
+        public bool Running => ComponentLifeStage.Starting <= LifeStage && LifeStage <= ComponentLifeStage.Stopping;
+
+        /// <inheritdoc />
+        [ViewVariables]
+        public bool Deleted => LifeStage >= ComponentLifeStage.Removing;
 
         /// <inheritdoc />
         [ViewVariables]
@@ -91,87 +154,56 @@ namespace Robust.Shared.GameObjects
             return (EntityEventBus) Owner.EntityManager.EventBus;
         }
 
-        /// <inheritdoc />
-        public virtual void OnRemove()
+        /// <summary>
+        /// Called when the component gets added to an entity.
+        /// </summary>
+        protected virtual void OnAdd()
         {
-            if (Running)
-                throw new InvalidOperationException("Cannot Remove a running entity!");
-
-            // We have been marked for deletion by the Component Manager.
-            Deleted = true;
-            GetBus().RaiseComponentEvent(this, CompRemoveInstance);
+            CreationTick = Owner.EntityManager.CurrentTick;
+            GetBus().RaiseComponentEvent(this, CompAddInstance);
+            LifeStage = ComponentLifeStage.Added;
         }
 
         /// <summary>
-        ///     Called when the component gets added to an entity.
+        /// Called when all of the entity's other components have been added and are available,
+        /// But are not necessarily initialized yet. DO NOT depend on the values of other components to be correct.
         /// </summary>
-        public virtual void OnAdd()
+        protected virtual void Initialize()
         {
-            if (Initialized)
-                throw new InvalidOperationException("Cannot Add an Initialized component!");
-
-            if (Running)
-                throw new InvalidOperationException("Cannot Add a running component!");
-
-            if (Deleted)
-                throw new InvalidOperationException("Cannot Add a Deleted component!");
-
-            CreationTick = Owner.EntityManager.CurrentTick;
-            GetBus().RaiseComponentEvent(this, CompAddInstance);
-        }
-
-        /// <inheritdoc />
-        public virtual void Initialize()
-        {
-            if (Initialized)
-                throw new InvalidOperationException("Component already Initialized!");
-
-            if (Running)
-                throw new InvalidOperationException("Cannot Initialize a running component!");
-
-            if (Deleted)
-                throw new InvalidOperationException("Cannot Initialize a Deleted component!");
-
-            Initialized = true;
             GetBus().RaiseComponentEvent(this, CompInitInstance);
+            LifeStage = ComponentLifeStage.Initialized;
         }
 
         /// <summary>
         ///     Starts up a component. This is called automatically after all components are Initialized and the entity is Initialized.
-        ///     This can be called multiple times during the component's life, and at any time.
         /// </summary>
+        /// <remarks>
+        /// Components are allowed to remove themselves in their own Startup function.
+        /// </remarks>
         protected virtual void Startup()
         {
-            if (!Initialized)
-                throw new InvalidOperationException("Cannot Start an uninitialized component!");
-
-            if (Running)
-                throw new InvalidOperationException("Cannot Startup a running component!");
-
-            if (Deleted)
-                throw new InvalidOperationException("Cannot Start a Deleted component!");
-
-            _running = true;
             GetBus().RaiseComponentEvent(this, CompStartupInstance);
+            LifeStage = ComponentLifeStage.Running;
         }
 
         /// <summary>
-        ///     Shuts down the component. The is called Automatically by OnRemove. This can be called multiple times during
-        ///     the component's life, and at any time.
+        ///     Shuts down the component. The is called Automatically by OnRemove.
         /// </summary>
         protected virtual void Shutdown()
         {
-            if (!Initialized)
-                throw new InvalidOperationException("Cannot Shutdown an uninitialized component!");
-
-            if (!Running)
-                throw new InvalidOperationException("Cannot Shutdown an unstarted component!");
-
-            if (Deleted)
-                throw new InvalidOperationException("Cannot Shutdown a Deleted component!");
-
-            _running = false;
             GetBus().RaiseComponentEvent(this, CompShutdownInstance);
+            LifeStage = ComponentLifeStage.Stopped;
+        }
+
+        /// <summary>
+        /// Called when the component is removed from an entity.
+        /// Shuts down the component.
+        /// The component has already been marked as deleted in the component manager.
+        /// </summary>
+        protected virtual void OnRemove()
+        {
+            GetBus().RaiseComponentEvent(this, CompRemoveInstance);
+            LifeStage = ComponentLifeStage.Deleted;
         }
 
         /// <inheritdoc />
@@ -244,6 +276,67 @@ namespace Robust.Shared.GameObjects
         }
     }
 
+    /// <summary>
+    /// The life stages of an ECS component.
+    /// </summary>
+    public enum ComponentLifeStage
+    {
+        /// <summary>
+        /// The component has just been allocated.
+        /// </summary>
+        PreAdd = 0,
+
+        /// <summary>
+        /// Currently being added to an entity.
+        /// </summary>
+        Adding,
+
+        /// <summary>
+        /// Has been added to an entity.
+        /// </summary>
+        Added,
+
+        /// <summary>
+        /// Currently being initialized.
+        /// </summary>
+        Initializing,
+
+        /// <summary>
+        /// Has been initialized.
+        /// </summary>
+        Initialized,
+
+        /// <summary>
+        /// Currently being started up.
+        /// </summary>
+        Starting,
+
+        /// <summary>
+        /// Has started up.
+        /// </summary>
+        Running,
+
+        /// <summary>
+        /// Currently shutting down.
+        /// </summary>
+        Stopping,
+
+        /// <summary>
+        /// Has been shut down.
+        /// </summary>
+        Stopped,
+
+        /// <summary>
+        /// Currently being removed from it's entity.
+        /// </summary>
+        Removing,
+
+        /// <summary>
+        /// Removed from it's entity, and is deleted.
+        /// </summary>
+        Deleted,
+    }
+
     /// <summary>
     /// The component has been added to the entity. This is the first function
     /// to be called after the component has been allocated and (optionally) deserialized.

Robust.Shared/GameObjects/ComponentExt.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using JetBrains.Annotations;
 using Robust.Shared.Log;
 
@@ -93,5 +94,21 @@ namespace Robust.Shared.GameObjects
 
             return entity.AddComponent<T>();
         }
+
+        public static IComponent SetAndDirtyIfChanged<TValue>(
+            this IComponent comp,
+            ref TValue backingField,
+            TValue value)
+        {
+            if (EqualityComparer<TValue>.Default.Equals(backingField, value))
+            {
+                return comp;
+            }
+
+            backingField = value;
+            comp.Dirty();
+
+            return comp;
+        }
     }
 }

Robust.Shared/GameObjects/ComponentManager.cs

@@ -164,19 +164,15 @@ namespace Robust.Shared.GameObjects
 
             _componentDependencyManager.OnComponentAdd(entity.Uid, component);
 
-            component.OnAdd();
+            component.LifeAddToEntity();
 
-            if (!entity.Initialized && !entity.Initializing) return;
+            if (!entity.Initialized && !entity.Initializing)
+                return;
 
-            component.Initialize();
-
-            DebugTools.Assert(component.Initialized, "Component is not initialized after calling Initialize(). "
-                                                     + "Did you forget to call base.Initialize() in an override?");
+            component.LifeInitialize();
 
             if (entity.Initialized)
-            {
-                component.Running = true;
-            }
+                component.LifeStartup();
         }
 
         /// <inheritdoc />
@@ -190,14 +186,14 @@ namespace Robust.Shared.GameObjects
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void RemoveComponent(EntityUid uid, Type type)
         {
-            RemoveComponentDeferred((Component) GetComponent(uid, type), uid, false);
+            RemoveComponentDeferred((Component)GetComponent(uid, type), uid, false);
         }
 
         /// <inheritdoc />
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void RemoveComponent(EntityUid uid, uint netId)
         {
-            RemoveComponentDeferred((Component) GetComponent(uid, netId), uid, false);
+            RemoveComponentDeferred((Component)GetComponent(uid, netId), uid, false);
         }
 
         /// <inheritdoc />
@@ -209,7 +205,7 @@ namespace Robust.Shared.GameObjects
             if (component.Owner == null || component.Owner.Uid != uid)
                 throw new InvalidOperationException("Component is not owned by entity.");
 
-            RemoveComponentDeferred((Component) component, uid, false);
+            RemoveComponentDeferred((Component)component, uid, false);
         }
 
         private static IEnumerable<Component> InSafeOrder(IEnumerable<Component> comps, bool forCreation = false)
@@ -260,23 +256,26 @@ namespace Robust.Shared.GameObjects
             try
             {
 #endif
-                // these two components are required on all entities and cannot be removed normally.
-                if (!removeProtected && (component is ITransformComponent || component is IMetaDataComponent))
-                {
-                    DebugTools.Assert("Tried to remove a protected component.");
-                    return;
-                }
+            // these two components are required on all entities and cannot be removed normally.
+            if (!removeProtected && (component is ITransformComponent || component is IMetaDataComponent))
+            {
+                DebugTools.Assert("Tried to remove a protected component.");
+                return;
+            }
 
-                if (!_deleteSet.Add(component))
-                {
-                    // already deferred deletion
-                    return;
-                }
+            if (!_deleteSet.Add(component))
+            {
+                // already deferred deletion
+                return;
+            }
 
-                component.Running = false;
-                component.OnRemove();
-                _componentDependencyManager.OnComponentRemove(uid, component);
-                ComponentRemoved?.Invoke(this, new RemovedComponentEventArgs(component, uid));
+            if (component.Running)
+                component.LifeShutdown();
+
+            if (component.LifeStage != ComponentLifeStage.PreAdd)
+                component.LifeRemoveFromEntity();
+            _componentDependencyManager.OnComponentRemove(uid, component);
+            ComponentRemoved?.Invoke(this, new RemovedComponentEventArgs(component, uid));
 #if EXCEPTION_TOLERANCE
             }
             catch (Exception e)
@@ -300,8 +299,12 @@ namespace Robust.Shared.GameObjects
                     return;
                 }
 
-                component.Running = false;
-                component.OnRemove(); // Sets delete
+                if (component.Running)
+                    component.LifeShutdown();
+
+                if (component.LifeStage != ComponentLifeStage.PreAdd)
+                    component.LifeRemoveFromEntity(); // Sets delete
+
                 ComponentRemoved?.Invoke(this, new RemovedComponentEventArgs(component, component.Owner.Uid));
 
             }
@@ -374,7 +377,7 @@ namespace Robust.Shared.GameObjects
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public T GetComponent<T>(EntityUid uid)
         {
-            return (T) GetComponent(uid, typeof(T));
+            return (T)GetComponent(uid, typeof(T));
         }
 
         /// <inheritdoc />
@@ -406,7 +409,7 @@ namespace Robust.Shared.GameObjects
             {
                 if (!comp.Deleted)
                 {
-                    component = (T) comp;
+                    component = (T)comp;
                     return true;
                 }
             }
@@ -486,7 +489,7 @@ namespace Robust.Shared.GameObjects
             {
                 if (comp.Deleted || !includePaused && comp.Paused) continue;
 
-                yield return (T) (object) comp;
+                yield return (T)(object)comp;
             }
         }
 
@@ -507,7 +510,7 @@ namespace Robust.Shared.GameObjects
                 if (!trait2.TryGetValue(uid, out var t2Comp) || t2Comp.Deleted || !includePaused && kvComp.Value.Paused)
                     continue;
 
-                yield return ((TComp1) (object) kvComp.Value, (TComp2) (object) t2Comp);
+                yield return ((TComp1)(object)kvComp.Value, (TComp2)(object)t2Comp);
             }
         }
 
@@ -531,9 +534,9 @@ namespace Robust.Shared.GameObjects
                 if (!trait3.TryGetValue(uid, out var t3Comp) || t3Comp.Deleted)
                     continue;
 
-                yield return ((TComp1) (object) kvComp.Value,
-                    (TComp2) (object) t2Comp,
-                    (TComp3) (object) t3Comp);
+                yield return ((TComp1)(object)kvComp.Value,
+                    (TComp2)(object)t2Comp,
+                    (TComp3)(object)t3Comp);
             }
         }
 
@@ -562,10 +565,10 @@ namespace Robust.Shared.GameObjects
                 if (!trait4.TryGetValue(uid, out var t4Comp) || t4Comp.Deleted)
                     continue;
 
-                yield return ((TComp1) (object) kvComp.Value,
-                    (TComp2) (object) t2Comp,
-                    (TComp3) (object) t3Comp,
-                    (TComp4) (object) t4Comp);
+                yield return ((TComp1)(object)kvComp.Value,
+                    (TComp2)(object)t2Comp,
+                    (TComp3)(object)t3Comp,
+                    (TComp4)(object)t4Comp);
             }
         }
 

Robust.Shared/GameObjects/ComponentMessages/Messages.cs

@@ -1,45 +0,0 @@
-using System;
-using JetBrains.Annotations;
-
-namespace Robust.Shared.GameObjects
-{
-    [Obsolete("Component Messages are deprecated, use Entity Events instead.")]
-    public class RelayMovementEntityMessage : ComponentMessage
-    {
-        [PublicAPI]
-        public readonly IEntity Entity;
-
-        public RelayMovementEntityMessage(IEntity entity)
-        {
-            Entity = entity;
-        }
-    }
-
-    /// <summary>
-    ///     The entity transform parent has been changed.
-    /// </summary>
-    [Obsolete("Component Messages are deprecated, use Entity Events instead.")]
-    public class ParentChangedMessage : ComponentMessage
-    {
-        /// <summary>
-        ///     The new parent of the transform.
-        /// </summary>
-        public IEntity? NewParent { get; }
-
-        /// <summary>
-        ///     The old parent of the transform.
-        /// </summary>
-        public IEntity? OldParent { get; }
-
-        /// <summary>
-        ///     Constructs a new instance of <see cref="ParentChangedMessage"/>.
-        /// </summary>
-        /// <param name="newParent">The new parent of the transform.</param>
-        /// <param name="oldParent">The old parent of the transform.</param>
-        public ParentChangedMessage(IEntity? newParent, IEntity? oldParent)
-        {
-            NewParent = newParent;
-            OldParent = oldParent;
-        }
-    }
-}

Robust.Shared/GameObjects/Components/Collidable/PhysicsComponent.Physics.cs

@@ -62,8 +62,9 @@ namespace Robust.Shared.GameObjects
 
         /// <summary>
         ///     Store the body's index within the island so we can lookup its data.
+        ///     Key is Island's ID and value is our index.
         /// </summary>
-        public int IslandIndex { get; set; }
+        public Dictionary<int, int> IslandIndex { get; set; } = new();
 
         // TODO: Actually implement after the initial pr dummy
         /// <summary>
@@ -283,7 +284,7 @@ namespace Robust.Shared.GameObjects
                 joints.Add(je.Joint);
             }
 
-            return new PhysicsComponentState(_canCollide, _sleepingAllowed, _fixedRotation, _bodyStatus, _fixtures, joints, _mass, LinearVelocity, AngularVelocity, BodyType);
+            return new PhysicsComponentState(_canCollide, _sleepingAllowed, _fixedRotation, _bodyStatus, _fixtures, joints, LinearVelocity, AngularVelocity, BodyType);
         }
 
         /// <inheritdoc />
@@ -514,15 +515,20 @@ namespace Robust.Shared.GameObjects
             Dirty();
         }
 
-        public Box2 GetWorldAABB(Vector2? worldPosition = null, Angle? worldRotation = null)
+        public Box2 GetWorldAABB(Vector2? worldPos = null, Angle? worldRot = null)
         {
-            worldRotation ??= Owner.Transform.WorldRotation;
-            worldPosition ??= Owner.Transform.WorldPosition;
-            var bounds = new Box2(worldPosition.Value, worldPosition.Value);
+            worldPos ??= Owner.Transform.WorldPosition;
+            worldRot ??= Owner.Transform.WorldRotation;
+
+            var worldPosValue = worldPos.Value;
+            var worldRotValue = worldRot.Value;
+
+            var bounds = new Box2(worldPosValue, worldPosValue);
 
             foreach (var fixture in _fixtures)
             {
-                bounds = bounds.Union(fixture.Shape.CalculateLocalBounds(worldRotation.Value).Translated(worldPosition.Value));
+                var boundy = fixture.Shape.CalculateLocalBounds(worldRotValue);
+                bounds = bounds.Union(boundy.Translated(worldPosValue));
             }
 
             return bounds;
@@ -1143,7 +1149,7 @@ namespace Robust.Shared.GameObjects
         }
 
         /// <inheritdoc />
-        public override void Initialize()
+        protected override void Initialize()
         {
             base.Initialize();
 
@@ -1248,7 +1254,7 @@ namespace Robust.Shared.GameObjects
             Logger.DebugS("physics", $"Removed joint id: {joint.ID} type: {joint.GetType().Name} from {Owner}");
         }
 
-        public override void OnRemove()
+        protected override void OnRemove()
         {
             base.OnRemove();
             // Need to do these immediately in case collision behaviors deleted the body

Robust.Shared/GameObjects/Components/Collidable/PhysicsComponentState.cs

@@ -18,10 +18,6 @@ namespace Robust.Shared.GameObjects
         public readonly List<Fixture> Fixtures;
         public readonly List<Joint> Joints;
 
-        /// <summary>
-        ///     Current mass of the entity, stored in grams.
-        /// </summary>
-        public readonly int Mass;
         public readonly Vector2 LinearVelocity;
         public readonly float AngularVelocity;
         public readonly BodyType BodyType;
@@ -35,7 +31,6 @@ namespace Robust.Shared.GameObjects
         /// <param name="status"></param>
         /// <param name="fixtures"></param>
         /// <param name="joints"></param>
-        /// <param name="mass">Current Mass of the entity.</param>
         /// <param name="linearVelocity">Current linear velocity of the entity in meters per second.</param>
         /// <param name="angularVelocity">Current angular velocity of the entity in radians per sec.</param>
         /// <param name="bodyType"></param>
@@ -46,7 +41,6 @@ namespace Robust.Shared.GameObjects
             BodyStatus status,
             List<Fixture> fixtures,
             List<Joint> joints,
-            float mass,
             Vector2 linearVelocity,
             float angularVelocity,
             BodyType bodyType)
@@ -61,7 +55,6 @@ namespace Robust.Shared.GameObjects
 
             LinearVelocity = linearVelocity;
             AngularVelocity = angularVelocity;
-            Mass = (int) Math.Round(mass * 1000); // rounds kg to nearest gram
             BodyType = bodyType;
         }
     }

Robust.Shared/GameObjects/Components/CollisionWakeComponent.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using Robust.Shared.Physics;
 using Robust.Shared.Players;
 using Robust.Shared.Serialization;
@@ -32,12 +33,12 @@ namespace Robust.Shared.GameObjects
             }
         }
 
-        private void RaiseStateChange()
+        internal void RaiseStateChange()
         {
             Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new CollisionWakeStateMessage(), false);
         }
 
-        public override void OnRemove()
+        protected override void OnRemove()
         {
             base.OnRemove();
             if (Owner.TryGetComponent(out IPhysBody? body))

Robust.Shared/GameObjects/Components/DebugExceptionComponents.cs

@@ -17,7 +17,7 @@ namespace Robust.Shared.GameObjects
     {
         public override string Name => "DebugExceptionOnAdd";
 
-        public override void OnAdd() => throw new NotSupportedException();
+        protected override void OnAdd() => throw new NotSupportedException();
     }
 
     /// <summary>
@@ -27,7 +27,7 @@ namespace Robust.Shared.GameObjects
     {
         public override string Name => "DebugExceptionInitialize";
 
-        public override void Initialize() => throw new NotSupportedException();
+        protected override void Initialize() => throw new NotSupportedException();
     }
 
     /// <summary>

Robust.Shared/GameObjects/Components/IgnorePauseComponent.cs

@@ -8,13 +8,13 @@ namespace Robust.Shared.GameObjects
     {
         public override string Name => "IgnorePause";
 
-        public override void OnAdd()
+        protected override void OnAdd()
         {
             base.OnAdd();
             Owner.Paused = false;
         }
 
-        public override void OnRemove()
+        protected override void OnRemove()
         {
             base.OnRemove();
             if (IoCManager.Resolve<IPauseManager>().IsMapPaused(Owner.Transform.MapID))

Robust.Shared/GameObjects/Components/Map/MapGridComponent.cs

@@ -1,8 +1,8 @@
 using System;
 using Robust.Shared.IoC;
-using Robust.Shared.Log;
 using Robust.Shared.Map;
-using Robust.Shared.Prototypes;
+using Robust.Shared.Maths;
+using Robust.Shared.Physics;
 using Robust.Shared.Players;
 using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager.Attributes;
@@ -18,6 +18,9 @@ namespace Robust.Shared.GameObjects
         GridId GridIndex { get; }
         IMapGrid Grid { get; }
         void ClearGridId();
+
+        bool AnchorEntity(ITransformComponent transform);
+        void UnanchorEntity(ITransformComponent transform);
     }
 
     /// <inheritdoc cref="IMapGridComponent"/>
@@ -47,12 +50,13 @@ namespace Robust.Shared.GameObjects
         [ViewVariables]
         public IMapGrid Grid => _mapManager.GetGrid(_gridIndex);
 
+        /// <inheritdoc />
         public void ClearGridId()
         {
             _gridIndex = GridId.Invalid;
         }
 
-        public override void Initialize()
+        protected override void Initialize()
         {
             base.Initialize();
             var mapId = Owner.Transform.MapID;
@@ -63,11 +67,54 @@ namespace Robust.Shared.GameObjects
             }
         }
 
+        /// <inheritdoc />
+        public bool AnchorEntity(ITransformComponent transform)
+        {
+            var xform = (TransformComponent) transform;
+            var tileIndices = Grid.TileIndicesFor(transform.Coordinates);
+            var result = Grid.AddToSnapGridCell(tileIndices, transform.Owner.Uid);
+
+            if (result)
+            {
+                xform.Parent = Owner.Transform;
+
+                // anchor snapping
+                xform.LocalPosition = Grid.GridTileToLocal(Grid.TileIndicesFor(xform.LocalPosition)).Position;
+
+                xform.SetAnchored(result);
+
+                if (xform.Owner.TryGetComponent<PhysicsComponent>(out var physicsComponent))
+                {
+                    physicsComponent.BodyType = BodyType.Static;
+                }
+            }
+
+            return result;
+        }
+
+        /// <inheritdoc />
+        public void UnanchorEntity(ITransformComponent transform)
+        {
+            //HACK: Client grid pivot causes this.
+            //TODO: make grid components the actual grid
+            if(GridIndex == GridId.Invalid)
+                return;
+
+            var xform = (TransformComponent)transform;
+            var tileIndices = Grid.TileIndicesFor(transform.Coordinates);
+            Grid.RemoveFromSnapGridCell(tileIndices, transform.Owner.Uid);
+            xform.SetAnchored(false);
+            if (xform.Owner.TryGetComponent<PhysicsComponent>(out var physicsComponent))
+            {
+                physicsComponent.BodyType = BodyType.Dynamic;
+            }
+        }
+
         /// <param name="player"></param>
         /// <inheritdoc />
         public override ComponentState GetComponentState(ICommonSession player)
         {
-            return new MapGridComponentState(_gridIndex, Grid.HasGravity);
+            return new MapGridComponentState(_gridIndex);
         }
 
         /// <inheritdoc />
@@ -75,11 +122,10 @@ namespace Robust.Shared.GameObjects
         {
             base.HandleComponentState(curState, nextState);
 
-            if (!(curState is MapGridComponentState state))
+            if (curState is not MapGridComponentState state)
                 return;
 
             _gridIndex = state.GridIndex;
-            Grid.HasGravity = state.HasGravity;
         }
     }
 
@@ -94,17 +140,14 @@ namespace Robust.Shared.GameObjects
         /// </summary>
         public GridId GridIndex { get; }
 
-        public bool HasGravity { get; }
-
         /// <summary>
         ///     Constructs a new instance of <see cref="MapGridComponentState"/>.
         /// </summary>
         /// <param name="gridIndex">Index of the grid this component is linked to.</param>
-        public MapGridComponentState(GridId gridIndex, bool hasGravity)
+        public MapGridComponentState(GridId gridIndex)
             : base(NetIDs.MAP_GRID)
         {
             GridIndex = gridIndex;
-            HasGravity = hasGravity;
         }
     }
 }

Robust.Shared/GameObjects/Components/Transform/SnapGridComponent.cs

@@ -1,24 +1,14 @@
-using Robust.Shared.Map;
-using Robust.Shared.Maths;
+using System;
 
 namespace Robust.Shared.GameObjects
 {
     /// <summary>
     /// Makes it possible to look this entity up with the snap grid.
     /// </summary>
+    [Obsolete("Use Transform.Anchored instead of this flag component.")]
     internal class SnapGridComponent : Component
     {
         /// <inheritdoc />
         public sealed override string Name => "SnapGrid";
-
-        /// <summary>
-        /// GridId the last time this component was moved.
-        /// </summary>
-        internal GridId LastGrid = GridId.Invalid;
-
-        /// <summary>
-        /// TileIndices the last time this component was moved.
-        /// </summary>
-        internal Vector2i LastTileIndices;
     }
 }

Robust.Shared/GameObjects/Components/Transform/TransformComponent.cs

@@ -26,6 +26,8 @@ namespace Robust.Shared.GameObjects
         private Angle _localRotation; // local rotation
         [DataField("noRot")]
         private bool _noLocalRotation;
+        [DataField("anchored")]
+        private bool _anchored;
 
         private Matrix3 _localMatrix = Matrix3.Identity;
         private Matrix3 _invLocalMatrix = Matrix3.Identity;
@@ -160,6 +162,11 @@ namespace Robust.Shared.GameObjects
             get => !_parent.IsValid() ? null : Owner.EntityManager.GetEntity(_parent).Transform;
             set
             {
+                if (_anchored && value?.Owner.Uid != _parent)
+                {
+                    Anchored = false;
+                }
+
                 if (value != null)
                 {
                     AttachParent(value);
@@ -212,6 +219,7 @@ namespace Robust.Shared.GameObjects
             }
         }
 
+        [Obsolete("Use ContainerHelper to check if this entity is inside a container.")]
         public bool IsMapTransform => !Owner.IsInContainer();
 
         /// <inheritdoc />
@@ -261,6 +269,10 @@ namespace Robust.Shared.GameObjects
             // NOTE: This setter must be callable from before initialize (inheriting from AttachParent's note)
             set
             {
+                // unless the parent is changing, nothing to do here
+                if(value.EntityId == _parent && _anchored)
+                    return;
+
                 var oldPosition = Coordinates;
                 _localPosition = value.Position;
 
@@ -268,6 +280,9 @@ namespace Robust.Shared.GameObjects
 
                 if (value.EntityId != _parent)
                 {
+                    if(_parent != EntityUid.Invalid) // Allow setting Transform.Parent in Prototypes
+                        Anchored = false; // changing the parent un-anchors the entity
+
                     changedParent = true;
                     var newParentEnt = Owner.EntityManager.GetEntity(value.EntityId);
                     var newParent = newParentEnt.Transform;
@@ -284,16 +299,11 @@ namespace Robust.Shared.GameObjects
                     var newConcrete = (TransformComponent) newParent;
                     newConcrete._children.Add(uid);
 
-                    var oldParentOwner = oldParent?.Owner;
-                    var entMessage = new EntParentChangedMessage(Owner, oldParentOwner);
-                    var compMessage = new ParentChangedMessage(newParentEnt, oldParentOwner);
-
                     // offset position from world to parent
                     _parent = newParentEnt.Uid;
                     ChangeMapId(newConcrete.MapID);
 
-                    Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, entMessage);
-                    Owner.SendMessage(this, compMessage);
+                    Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new EntParentChangedMessage(Owner, oldParent?.Owner));
 
                     GridID = GetGridIndex();
                 }
@@ -310,7 +320,8 @@ namespace Robust.Shared.GameObjects
                     //TODO: This is a hack, look into WHY we can't call GridPosition before the comp is Running
                     if (Running)
                     {
-                        Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new MoveEvent(Owner, oldPosition, Coordinates));
+                        if(!oldPosition.Position.Equals(Coordinates.Position))
+                            Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new MoveEvent(Owner, oldPosition, Coordinates));
                     }
                 }
                 else
@@ -330,6 +341,9 @@ namespace Robust.Shared.GameObjects
             get => _localPosition;
             set
             {
+                if(Anchored)
+                    return;
+
                 if (_localPosition.EqualsApprox(value, 0.00001))
                     return;
 
@@ -353,17 +367,38 @@ namespace Robust.Shared.GameObjects
         }
 
         /// <inheritdoc />
-        [ViewVariables]
+        [ViewVariables(VVAccess.ReadWrite)]
         public bool Anchored
         {
-            get => Owner.HasComponent<SnapGridComponent>();
+            get => _anchored;
             set
             {
-                if(value && !Owner.HasComponent<SnapGridComponent>())
-                    Owner.AddComponent<SnapGridComponent>();
-
-                else if(!value && Owner.HasComponent<SnapGridComponent>())
-                    Owner.RemoveComponent<SnapGridComponent>();
+                // This will be set again when the transform starts, actually anchoring it.
+                if (LifeStage < ComponentLifeStage.Starting)
+                {
+                    _anchored = value;
+                }
+                else if (LifeStage == ComponentLifeStage.Starting)
+                {
+                    if (value && _mapManager.TryFindGridAt(MapPosition, out var grid))
+                    {
+                        _anchored = Owner.EntityManager.GetEntity(grid.GridEntityId).GetComponent<IMapGridComponent>().AnchorEntity(this);
+                    }
+                }
+                else if (value && !_anchored && _mapManager.TryFindGridAt(MapPosition, out var grid))
+                {
+                    _anchored = Owner.EntityManager.GetEntity(grid.GridEntityId).GetComponent<IMapGridComponent>().AnchorEntity(this);
+                }
+                else if (!value && _anchored)
+                {
+                    // An anchored entity is always parented to the grid.
+                    // If Transform.Anchored is true in the prototype but the entity was not spawned with a grid as the parent,
+                    // then this will be false.
+                    if (Owner.EntityManager.ComponentManager.TryGetComponent<IMapGridComponent>(ParentUid, out var gridComp))
+                        gridComp.UnanchorEntity(this);
+                    else
+                        SetAnchored(false);
+                }
             }
         }
 
@@ -404,7 +439,7 @@ namespace Robust.Shared.GameObjects
         [ViewVariables] public EntityUid LerpParent { get; private set; }
 
         /// <inheritdoc />
-        public override void Initialize()
+        protected override void Initialize()
         {
             base.Initialize();
 
@@ -482,6 +517,10 @@ namespace Robust.Shared.GameObjects
         /// <inheritdoc />
         protected override void Startup()
         {
+            // Re-Anchor the entity if needed.
+            if (_anchored)
+                Anchored = true;
+
             base.Startup();
 
             // Keep the cached matrices in sync with the fields.
@@ -568,17 +607,14 @@ namespace Robust.Shared.GameObjects
                 return;
             }
 
+            Anchored = false;
+
             var oldConcrete = (TransformComponent) oldParent;
             var uid = Owner.Uid;
             oldConcrete._children.Remove(uid);
 
-            var oldParentOwner = oldParent?.Owner;
-
-            var entMessage = new EntParentChangedMessage(Owner, oldParentOwner);
-            var compMessage = new ParentChangedMessage(null, oldParentOwner);
             _parent = EntityUid.Invalid;
-            Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, entMessage);
-            Owner.SendMessage(this, compMessage);
+            Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new EntParentChangedMessage(Owner, oldParent?.Owner));
             var oldMapId = MapID;
             MapID = MapId.Nullspace;
 
@@ -687,7 +723,7 @@ namespace Robust.Shared.GameObjects
         /// <inheritdoc />
         public override ComponentState GetComponentState(ICommonSession player)
         {
-            return new TransformComponentState(_localPosition, LocalRotation, _parent, _noLocalRotation);
+            return new TransformComponentState(_localPosition, LocalRotation, _parent, _noLocalRotation, _anchored);
         }
 
         /// <inheritdoc />
@@ -737,6 +773,16 @@ namespace Robust.Shared.GameObjects
                 _prevPosition = newState.LocalPosition;
                 _prevRotation = newState.Rotation;
 
+                Anchored = newState.Anchored;
+
+                // This is not possible, because client entities don't exist on the server, so the parent HAS to be a shared entity.
+                // If this assert fails, the code above that sets the parent is broken.
+                DebugTools.Assert(!_parent.IsClientSide(), "Transform received a state, but is still parented to a client entity.");
+
+                // Whatever happened on the client, these should still be correct
+                DebugTools.Assert(ParentUid == newState.ParentID);
+                DebugTools.Assert(Anchored == newState.Anchored);
+
                 if (rebuildMatrices)
                 {
                     RebuildMatrices();
@@ -837,6 +883,11 @@ namespace Robust.Shared.GameObjects
             /// </summary>
             public readonly bool NoLocalRotation;
 
+            /// <summary>
+            /// True if the transform is anchored to a tile.
+            /// </summary>
+            public readonly bool Anchored;
+
             /// <summary>
             ///     Constructs a new state snapshot of a TransformComponent.
             /// </summary>
@@ -844,15 +895,24 @@ namespace Robust.Shared.GameObjects
             /// <param name="rotation">Current direction offset of this entity.</param>
             /// <param name="parentId">Current parent transform of this entity.</param>
             /// <param name="noLocalRotation"></param>
-            public TransformComponentState(Vector2 localPosition, Angle rotation, EntityUid parentId, bool noLocalRotation)
+            public TransformComponentState(Vector2 localPosition, Angle rotation, EntityUid parentId, bool noLocalRotation, bool anchored)
                 : base(NetIDs.TRANSFORM)
             {
                 LocalPosition = localPosition;
                 Rotation = rotation;
                 ParentID = parentId;
                 NoLocalRotation = noLocalRotation;
+                Anchored = anchored;
             }
         }
+
+        public void SetAnchored(bool value)
+        {
+            _anchored = value;
+            Dirty();
+
+            Owner.EntityManager.EventBus.RaiseLocalEvent(Owner.Uid, new AnchorStateChangedEvent());
+        }
     }
 
     /// <summary>
@@ -900,4 +960,9 @@ namespace Robust.Shared.GameObjects
         /// </summary>
         public Box2? WorldAABB { get; }
     }
+
+    /// <summary>
+    /// Raised when the Anchor state of the transform is changed.
+    /// </summary>
+    public class AnchorStateChangedEvent : EntityEventArgs { }
 }

Robust.Shared/GameObjects/Entity.cs

@@ -84,6 +84,7 @@ namespace Robust.Shared.GameObjects
                     return;
 
                 _paused = value;
+                EntityManager.EventBus.RaiseLocalEvent(Uid, new EntityPausedEvent(Uid, value));
             }
         }
 
@@ -134,13 +135,13 @@ namespace Robust.Shared.GameObjects
                     _ => int.MaxValue
                 });
 
-            foreach (var comp in components)
+            foreach (var component in components)
             {
-                if (comp == null || comp.Initialized) continue;
+                var comp = (Component) component;
+                if (comp.Initialized)
+                    continue;
 
-                comp.Initialize();
-
-                DebugTools.Assert(comp.Initialized, $"Component {comp.Name} did not call base {nameof(comp.Initialize)} in derived method.");
+                comp.LifeInitialize();
             }
 
 #if DEBUG
@@ -173,11 +174,12 @@ namespace Robust.Shared.GameObjects
                     _ => int.MaxValue
                 });
 
-            foreach (var comp in comps)
+            foreach (var component in comps)
             {
-                if (comp != null && comp.Initialized && !comp.Deleted)
+                var comp = (Component) component;
+                if (comp.LifeStage == ComponentLifeStage.Initialized)
                 {
-                    comp.Running = true;
+                    comp.LifeStartup();
                 }
             }
         }

Robust.Shared/GameObjects/EntityEventBus.Broadcast.cs

@@ -24,6 +24,15 @@ namespace Robust.Shared.GameObjects
         void SubscribeEvent<T>(EventSource source, IEntityEventSubscriber subscriber,
             EntityEventHandler<T> eventHandler) where T : notnull;
 
+        void SubscribeEvent<T>(
+            EventSource source,
+            IEntityEventSubscriber subscriber,
+            EntityEventHandler<T> eventHandler,
+            Type orderType,
+            Type[]? before=null,
+            Type[]? after=null)
+            where T : notnull;
+
         /// <summary>
         /// Unsubscribes all event handlers of a given type.
         /// </summary>
@@ -137,7 +146,7 @@ namespace Robust.Shared.GameObjects
                 return;
 
             // UnsubscribeEvent modifies _inverseEventSubscriptions, requires val to be cached
-            foreach (var (type, (source, originalHandler, handler)) in val.ToList())
+            foreach (var (type, (source, originalHandler, handler, _)) in val.ToList())
             {
                 UnsubscribeEvent(source, type, originalHandler, handler, subscriber);
             }
@@ -154,7 +163,36 @@ namespace Robust.Shared.GameObjects
         }
 
         /// <inheritdoc />
-        public void SubscribeEvent<T>(EventSource source, IEntityEventSubscriber subscriber, EntityEventHandler<T> eventHandler) where T : notnull
+        public void SubscribeEvent<T>(
+            EventSource source,
+            IEntityEventSubscriber subscriber,
+            EntityEventHandler<T> eventHandler)
+            where T : notnull
+        {
+            SubscribeEventCommon(source, subscriber, eventHandler, null);
+        }
+
+        public void SubscribeEvent<T>(
+            EventSource source,
+            IEntityEventSubscriber subscriber,
+            EntityEventHandler<T> eventHandler,
+            Type orderType,
+            Type[]? before=null,
+            Type[]? after=null)
+            where T : notnull
+        {
+            var order = new OrderingData(orderType, before, after);
+
+            SubscribeEventCommon(source, subscriber, eventHandler, order);
+            HandleOrderRegistration(typeof(T), order);
+        }
+
+        private void SubscribeEventCommon<T>(
+            EventSource source,
+            IEntityEventSubscriber subscriber,
+            EntityEventHandler<T> eventHandler,
+            OrderingData? order)
+            where T : notnull
         {
             if (source == EventSource.None)
                 throw new ArgumentOutOfRangeException(nameof(source));
@@ -166,7 +204,7 @@ namespace Robust.Shared.GameObjects
                 throw new ArgumentNullException(nameof(subscriber));
 
             var eventType = typeof(T);
-            var subscriptionTuple = new Registration(source, eventHandler, ev => eventHandler((T) ev), eventHandler);
+            var subscriptionTuple = new Registration(source, eventHandler, ev => eventHandler((T) ev), eventHandler, order);
             if (!_eventSubscriptions.TryGetValue(eventType, out var subscriptions))
                 _eventSubscriptions.Add(eventType, new List<Registration> {subscriptionTuple});
             else if (!subscriptions.Any(p => p.Mask == source && p.Original == (Delegate) eventHandler))
@@ -184,7 +222,6 @@ namespace Robust.Shared.GameObjects
                     inverseSubscription
                 );
             }
-
             else if (!inverseSubscription.ContainsKey(eventType))
             {
                 inverseSubscription.Add(eventType, subscriptionTuple);
@@ -290,15 +327,13 @@ namespace Robust.Shared.GameObjects
                 });
             }
 
-
-
             _awaitingMessages.Add(type, (source, reg, tcs));
             return tcs.Task;
         }
 
         private void UnsubscribeEvent(EventSource source, Type eventType, Delegate originalHandler, EventHandler handler, IEntityEventSubscriber subscriber)
         {
-            var tuple = new Registration(source, originalHandler, handler, originalHandler);
+            var tuple = new Registration(source, originalHandler, handler, originalHandler, null);
             if (_eventSubscriptions.TryGetValue(eventType, out var subscriptions) && subscriptions.Contains(tuple))
                 subscriptions.Remove(tuple);
 
@@ -310,7 +345,11 @@ namespace Robust.Shared.GameObjects
         {
             var eventType = eventArgs.GetType();
 
-            if (_eventSubscriptions.TryGetValue(eventType, out var subs))
+            if (_orderedEvents.Contains(eventType))
+            {
+                ProcessSingleEventOrdered(source, eventArgs, eventType);
+            }
+            else if (_eventSubscriptions.TryGetValue(eventType, out var subs))
             {
                 foreach (var handler in subs)
                 {
@@ -319,25 +358,20 @@ namespace Robust.Shared.GameObjects
                 }
             }
 
-            if (_awaitingMessages.TryGetValue(eventType, out var awaiting))
-            {
-                var (mask, _, tcs) = awaiting;
-
-                if ((source & mask) != 0)
-                {
-                    tcs.TrySetResult(eventArgs);
-                    _awaitingMessages.Remove(eventType);
-                }
-            }
+            ProcessAwaitingMessages(source, eventArgs, eventType);
         }
 
         private void ProcessSingleEvent<T>(EventSource source, T eventArgs) where T : notnull
         {
             var eventType = typeof(T);
 
-            if (_eventSubscriptions.TryGetValue(eventType, out var subs))
+            if (_orderedEvents.Contains(eventType))
             {
-                foreach (var (mask, originalHandler, _) in subs)
+                ProcessSingleEventOrdered(source, eventArgs, eventType);
+            }
+            else if (_eventSubscriptions.TryGetValue(eventType, out var subs))
+            {
+                foreach (var (mask, originalHandler, _, _) in subs)
                 {
                     if ((mask & source) != 0)
                     {
@@ -347,6 +381,13 @@ namespace Robust.Shared.GameObjects
                 }
             }
 
+            ProcessAwaitingMessages(source, eventArgs, eventType);
+        }
+
+        // Generic here so we can avoid boxing alloc unless actually awaiting.
+        private void ProcessAwaitingMessages<T>(EventSource source, T eventArgs, Type eventType)
+            where T : notnull
+        {
             if (_awaitingMessages.TryGetValue(eventType, out var awaiting))
             {
                 var (mask1, _, tcs) = awaiting;
@@ -366,13 +407,20 @@ namespace Robust.Shared.GameObjects
 
             public readonly Delegate Original;
             public readonly EventHandler Handler;
+            public readonly OrderingData? Ordering;
 
-            public Registration(EventSource mask, Delegate original, EventHandler handler, object equalityToken)
+            public Registration(
+                EventSource mask,
+                Delegate original,
+                EventHandler handler,
+                object equalityToken,
+                OrderingData? ordering)
             {
                 Mask = mask;
                 Original = original;
                 Handler = handler;
                 EqualityToken = equalityToken;
+                Ordering = ordering;
             }
 
             public bool Equals(Registration other)
@@ -403,11 +451,16 @@ namespace Robust.Shared.GameObjects
                 return !left.Equals(right);
             }
 
-            public void Deconstruct(out EventSource mask, out Delegate originalHandler, out EventHandler handler)
+            public void Deconstruct(
+                out EventSource mask,
+                out Delegate originalHandler,
+                out EventHandler handler,
+                out OrderingData? order)
             {
                 mask = Mask;
                 originalHandler = Original;
                 handler = Handler;
+                order = Ordering;
             }
         }
     }

Robust.Shared/GameObjects/EntityEventBus.Directed.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Robust.Shared.GameObjects
 {
@@ -14,6 +16,12 @@ namespace Robust.Shared.GameObjects
             where TComp : IComponent
             where TEvent : EntityEventArgs;
 
+        void SubscribeLocalEvent<TComp, TEvent>(
+            ComponentEventHandler<TComp, TEvent> handler,
+            Type orderType, Type[]? before=null, Type[]? after=null)
+            where TComp : IComponent
+            where TEvent : EntityEventArgs;
+
         [Obsolete("Use the overload without the handler argument.")]
         void UnsubscribeLocalEvent<TComp, TEvent>(ComponentEventHandler<TComp, TEvent> handler)
             where TComp : IComponent
@@ -61,6 +69,12 @@ namespace Robust.Shared.GameObjects
         public void RaiseLocalEvent<TEvent>(EntityUid uid, TEvent args, bool broadcast = true)
             where TEvent : EntityEventArgs
         {
+            if (_orderedEvents.Contains(typeof(TEvent)))
+            {
+                RaiseLocalOrdered(uid, args, broadcast);
+                return;
+            }
+
             _eventTables.Dispatch(uid, typeof(TEvent), args);
 
             // we also broadcast it so the call site does not have to.
@@ -76,7 +90,24 @@ namespace Robust.Shared.GameObjects
             void EventHandler(EntityUid uid, IComponent comp, EntityEventArgs args)
                 => handler(uid, (TComp) comp, (TEvent) args);
 
-            _eventTables.Subscribe(typeof(TComp), typeof(TEvent), EventHandler);
+            _eventTables.Subscribe(typeof(TComp), typeof(TEvent), EventHandler, null);
+        }
+
+        public void SubscribeLocalEvent<TComp, TEvent>(
+            ComponentEventHandler<TComp, TEvent> handler,
+            Type orderType,
+            Type[]? before=null,
+            Type[]? after=null)
+            where TComp : IComponent
+            where TEvent : EntityEventArgs
+        {
+            void EventHandler(EntityUid uid, IComponent comp, EntityEventArgs args)
+                => handler(uid, (TComp) comp, (TEvent) args);
+
+            var orderData = new OrderingData(orderType, before, after);
+
+            _eventTables.Subscribe(typeof(TComp), typeof(TEvent), EventHandler, orderData);
+            HandleOrderRegistration(typeof(TEvent), orderData);
         }
 
         /// <inheritdoc />
@@ -105,7 +136,7 @@ namespace Robust.Shared.GameObjects
             private Dictionary<EntityUid, Dictionary<Type, HashSet<Type>>> _eventTables;
 
             // EventType -> CompType -> Handler
-            private Dictionary<Type, Dictionary<Type, DirectedEventHandler>> _subscriptions;
+            private Dictionary<Type, Dictionary<Type, (DirectedEventHandler handler, OrderingData? ordering)>> _subscriptions;
 
             // prevents shitcode, get your subscriptions figured out before you start spawning entities
             private bool _subscriptionLock;
@@ -148,25 +179,21 @@ namespace Robust.Shared.GameObjects
                 RemoveComponent(e.OwnerUid, e.Component.GetType());
             }
 
-            public void Subscribe(Type compType, Type eventType, DirectedEventHandler handler)
+            public void Subscribe(Type compType, Type eventType, DirectedEventHandler handler, OrderingData? order)
             {
                 if (_subscriptionLock)
                     throw new InvalidOperationException("Subscription locked.");
 
                 if (!_subscriptions.TryGetValue(compType, out var compSubs))
                 {
-                    compSubs = new Dictionary<Type, DirectedEventHandler>();
+                    compSubs = new Dictionary<Type, (DirectedEventHandler, OrderingData?)>();
                     _subscriptions.Add(compType, compSubs);
-
-                    compSubs.Add(eventType, handler);
                 }
-                else
-                {
-                    if (compSubs.ContainsKey(eventType))
-                        throw new InvalidOperationException($"Duplicate Subscriptions for comp={compType.Name}, event={eventType.Name}");
 
-                    compSubs.Add(eventType, handler);
-                }
+                if (compSubs.ContainsKey(eventType))
+                    throw new InvalidOperationException($"Duplicate Subscriptions for comp={compType.Name}, event={eventType.Name}");
+
+                compSubs.Add(eventType, (handler, order));
             }
 
             public void Unsubscribe(Type compType, Type eventType)
@@ -196,7 +223,8 @@ namespace Robust.Shared.GameObjects
             {
                 var eventTable = _eventTables[euid];
 
-                foreach (var type in GetReferences(compType))
+                var enumerator = GetReferences(compType);
+                while (enumerator.MoveNext(out var type))
                 {
                     if (!_subscriptions.TryGetValue(type, out var compSubs))
                         continue;
@@ -218,7 +246,8 @@ namespace Robust.Shared.GameObjects
             {
                 var eventTable = _eventTables[euid];
 
-                foreach (var type in GetReferences(compType))
+                var enumerator = GetReferences(compType);
+                while (enumerator.MoveNext(out var type))
                 {
                     if (!_subscriptions.TryGetValue(type, out var compSubs))
                         continue;
@@ -245,25 +274,53 @@ namespace Robust.Shared.GameObjects
                     if(!_subscriptions.TryGetValue(compType, out var compSubs))
                         return;
 
-                    if(!compSubs.TryGetValue(eventType, out var handler))
+                    if(!compSubs.TryGetValue(eventType, out var sub))
                         return;
 
+                    var (handler, _) = sub;
                     var component = _entMan.ComponentManager.GetComponent(euid, compType);
 
                     handler(euid, component, args);
                 }
             }
 
+            public void CollectOrdered(
+                EntityUid euid,
+                Type eventType,
+                List<(EventHandler, OrderingData?)> found)
+            {
+                var eventTable = _eventTables[euid];
+
+                if(!eventTable.TryGetValue(eventType, out var subscribedComps))
+                    return;
+
+                foreach (var compType in subscribedComps)
+                {
+                    if(!_subscriptions.TryGetValue(compType, out var compSubs))
+                        return;
+
+                    if(!compSubs.TryGetValue(eventType, out var sub))
+                        return;
+
+                    var (handler, order) = sub;
+                    var component = _entMan.ComponentManager.GetComponent(euid, compType);
+
+                    found.Add((ev => handler(euid, component, (EntityEventArgs) ev), order));
+                }
+            }
+
             public void DispatchComponent(EntityUid euid, IComponent component, Type eventType, EntityEventArgs args)
             {
-                foreach (var type in GetReferences(component.GetType()))
+                var enumerator = GetReferences(component.GetType());
+                while (enumerator.MoveNext(out var type))
                 {
                     if (!_subscriptions.TryGetValue(type, out var compSubs))
                         continue;
 
-                    if (!compSubs.TryGetValue(eventType, out var handler))
+                    if (!compSubs.TryGetValue(eventType, out var sub))
                         continue;
 
+                    var (handler, _) = sub;
                     handler(euid, component, args);
                 }
             }
@@ -294,9 +351,49 @@ namespace Robust.Shared.GameObjects
                 _subscriptions = null!;
             }
 
-            private IEnumerable<Type> GetReferences(Type type)
+            /// <summary>
+            ///     Enumerates the type's component references, returning the type itself last.
+            /// </summary>
+            private ReferencesEnumerator GetReferences(Type type)
             {
-                return _comFac.GetRegistration(type).References;
+                return new(type, _comFac.GetRegistration(type).References);
+            }
+
+            private struct ReferencesEnumerator
+            {
+                private readonly Type _baseType;
+                private readonly IReadOnlyList<Type> _list;
+                private readonly int _totalLength;
+                private int _idx;
+
+                public ReferencesEnumerator(Type baseType, IReadOnlyList<Type> list)
+                {
+                    _baseType = baseType;
+                    _list = list;
+                    _totalLength = list.Count;
+                    _idx = 0;
+                }
+
+                public bool MoveNext([NotNullWhen(true)] out Type? type)
+                {
+                    if (_idx >= _totalLength)
+                    {
+                        if (_idx++ == _totalLength)
+                        {
+                            type = _baseType;
+                            return true;
+                        }
+
+                        type = null;
+                        return false;
+                    }
+
+                    type = _list[_idx++];
+                    if (type == _baseType)
+                        return MoveNext(out type);
+
+                    return true;
+                }
             }
         }
 

Robust.Shared/GameObjects/EntityEventBus.Ordering.cs

@@ -0,0 +1,95 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Robust.Shared.Utility;
+
+namespace Robust.Shared.GameObjects
+{
+    internal partial class EntityEventBus
+    {
+        // TODO: Topological sort is currently done every time an event is emitted.
+        // This should be fine for low-volume stuff like interactions, but definitely not for anything high volume.
+        // Not sure if we could pre-cache the topological sort, here.
+
+        // Ordered event raising is slow so if this event has any ordering dependencies we use a slower path.
+        private readonly HashSet<Type> _orderedEvents = new();
+
+        private void ProcessSingleEventOrdered(EventSource source, object eventArgs, Type eventType)
+        {
+            var found = new List<(EventHandler, OrderingData?)>();
+
+            CollectBroadcastOrdered(source, eventType, found);
+
+            DispatchOrderedEvents(eventArgs, found);
+        }
+
+        private void CollectBroadcastOrdered(
+            EventSource source,
+            Type eventType,
+            List<(EventHandler, OrderingData?)> found)
+        {
+            if (!_eventSubscriptions.TryGetValue(eventType, out var subs))
+                return;
+
+            foreach (var handler in subs)
+            {
+                if ((handler.Mask & source) != 0)
+                    found.Add((handler.Handler, handler.Ordering));
+            }
+        }
+
+        private void RaiseLocalOrdered<TEvent>(
+            EntityUid uid,
+            TEvent args,
+            bool broadcast)
+            where TEvent : EntityEventArgs
+        {
+            var found = new List<(EventHandler, OrderingData?)>();
+
+            if (broadcast)
+                CollectBroadcastOrdered(EventSource.Local, typeof(TEvent), found);
+
+            _eventTables.CollectOrdered(uid, typeof(TEvent), found);
+
+            DispatchOrderedEvents(args, found);
+
+            if (broadcast)
+                ProcessAwaitingMessages(EventSource.Local, args, typeof(TEvent));
+        }
+
+        private static void DispatchOrderedEvents(object eventArgs, List<(EventHandler, OrderingData?)> found)
+        {
+            var nodes = TopologicalSort.FromBeforeAfter(
+                found.Where(f => f.Item2 != null),
+                n => n.Item2!.OrderType,
+                n => n.Item1!,
+                n => n.Item2!.Before ?? Array.Empty<Type>(),
+                n => n.Item2!.After ?? Array.Empty<Type>(),
+                allowMissing: true);
+
+            foreach (var handler in TopologicalSort.Sort(nodes))
+            {
+                handler(eventArgs);
+            }
+
+            // Go over all handlers that don't have ordering so weren't included in the sort.
+            foreach (var (handler, orderData) in found)
+            {
+                if (orderData == null)
+                    handler(eventArgs);
+            }
+        }
+
+        private void HandleOrderRegistration(Type eventType, OrderingData? data)
+        {
+            if (data == null)
+                return;
+
+            if (data.Before != null || data.After != null)
+                _orderedEvents.Add(eventType);
+        }
+
+        private sealed record OrderingData(Type OrderType, Type[]? Before, Type[]? After);
+
+    }
+}

Robust.Shared/GameObjects/EntityLifeState.cs

@@ -1,5 +1,8 @@
 namespace Robust.Shared.GameObjects
 {
+    /// <summary>
+    /// The life stages of an ECS Entity.
+    /// </summary>
     public enum EntityLifeStage
     {
         /// <summary>

Robust.Shared/GameObjects/EntityManager.cs

@@ -1,14 +1,11 @@
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
-using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
 using Prometheus;
-using Robust.Shared.IoC;
-using Robust.Shared.Log;
 using Robust.Shared.Map;
-using Robust.Shared.Maths;
-using Robust.Shared.Physics;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Timing;
 using Robust.Shared.Utility;
@@ -79,7 +76,6 @@ namespace Robust.Shared.GameObjects
             _eventBus = new EntityEventBus(this);
 
             ComponentManager.Initialize();
-            _componentManager.ComponentRemoved += (sender, args) => _eventBus.UnsubscribeEvents(args.Component);
         }
 
         public virtual void Startup()
@@ -142,6 +138,11 @@ namespace Robust.Shared.GameObjects
 
         #region Entity Management
 
+        public IEntity CreateEntityUninitialized(string? prototypeName, EntityUid? euid)
+        {
+            return CreateEntity(prototypeName, euid);
+        }
+
         /// <inheritdoc />
         public virtual IEntity CreateEntityUninitialized(string? prototypeName)
         {
@@ -153,9 +154,8 @@ namespace Robust.Shared.GameObjects
         {
             var newEntity = CreateEntity(prototypeName);
 
-            if (TryGetEntity(coordinates.EntityId, out var entity))
+            if (coordinates.IsValid(this))
             {
-                newEntity.Transform.AttachParent(entity);
                 newEntity.Transform.Coordinates = coordinates;
             }
 
@@ -224,12 +224,7 @@ namespace Robust.Shared.GameObjects
             return false;
         }
 
-        [Obsolete("IEntityQuery is obsolete")]
-        public IEnumerable<IEntity> GetEntities(IEntityQuery query)
-        {
-            return query.Match(this);
-        }
-
+        /// <inheritdoc />
         public IEnumerable<IEntity> GetEntities()
         {
             // Need to do an iterator loop to avoid issues with concurrent access.

Robust.Shared/GameObjects/EntityQuery.cs

@@ -1,178 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using JetBrains.Annotations;
-using Robust.Shared.Physics;
-using Robust.Shared.Utility;
-
-namespace Robust.Shared.GameObjects
-{
-    /// <summary>
-    ///     An entity query that will let all entities pass.
-    ///     This is the same as matching <c>ITransformComponent</c>, but faster.
-    /// </summary>
-    [PublicAPI, Obsolete]
-    public class AllEntityQuery : IEntityQuery
-    {
-        /// <inheritdoc />
-        public bool Match(IEntity entity) => true;
-
-        /// <inheritdoc />
-        public IEnumerable<IEntity> Match(IEntityManager entityMan)
-        {
-            return entityMan.GetEntities();
-        }
-    }
-
-    /// <summary>
-    ///     An entity query which will match entities based on a predicate.
-    ///     If you only want a single type of Component, use <c>TypeEntityQuery</c>.
-    /// </summary>
-    [PublicAPI, Obsolete]
-    public class PredicateEntityQuery : IEntityQuery
-    {
-        private readonly Predicate<IEntity> Predicate;
-
-        /// <summary>
-        ///     Constructs a new instance of <c>PredicateEntityQuery</c>.
-        /// </summary>
-        /// <param name="predicate"></param>
-        public PredicateEntityQuery(Predicate<IEntity> predicate)
-        {
-            if (predicate == null)
-                throw new ArgumentNullException(nameof(predicate));
-
-            Predicate = predicate;
-        }
-
-        /// <inheritdoc />
-        public bool Match(IEntity entity) => Predicate(entity);
-
-        /// <inheritdoc />
-        public IEnumerable<IEntity> Match(IEntityManager entityMan)
-        {
-            return entityMan.GetEntities().Where(entity => Predicate(entity));
-        }
-    }
-
-    /// <summary>
-    ///     An entity query that will match one type of component.
-    ///     This the fastest and most common query, and should be the default choice.
-    /// </summary>
-    [PublicAPI, Obsolete]
-    public class TypeEntityQuery : IEntityQuery
-    {
-        private readonly Type ComponentType;
-
-        /// <summary>
-        ///     Constructs a new instance of <c>TypeEntityQuery</c>.
-        /// </summary>
-        /// <param name="componentType">Type of the component to match.</param>
-        public TypeEntityQuery(Type componentType)
-        {
-            DebugTools.Assert(typeof(IComponent).IsAssignableFrom(componentType), "componentType must inherit IComponent");
-
-            ComponentType = componentType;
-        }
-
-        /// <inheritdoc />
-        public bool Match(IEntity entity) => entity.HasComponent(ComponentType);
-
-        /// <inheritdoc />
-        public IEnumerable<IEntity> Match(IEntityManager entityMan)
-        {
-            return entityMan.ComponentManager.GetAllComponents(ComponentType, true).Select(component => component.Owner);
-        }
-    }
-
-    /// <summary>
-    ///     An entity query that will match one type of component.
-    ///     This the fastest and most common query, and should be the default choice.
-    /// </summary>
-    /// <typeparamref name="T">Type of component to match.</typeparamref>
-    [PublicAPI, Obsolete]
-    public class TypeEntityQuery<T> : IEntityQuery where T : IComponent
-    {
-        public bool Match(IEntity entity) => entity.HasComponent<T>();
-
-        public IEnumerable<IEntity> Match(IEntityManager entityMan)
-        {
-            return entityMan.ComponentManager.EntityQuery<T>(true).Select(component => component.Owner);
-        }
-    }
-
-    /// <summary>
-    ///     An entity query that will match all entities that intersect with the argument entity.
-    /// </summary>
-    [PublicAPI, Obsolete]
-    public class IntersectingEntityQuery : IEntityQuery
-    {
-        private readonly IEntity Entity;
-
-        /// <summary>
-        ///     Constructs a new instance of <c>TypeEntityQuery</c>.
-        /// </summary>
-        /// <param name="componentType">Type of the component to match.</param>
-        public IntersectingEntityQuery(IEntity entity)
-        {
-            Entity = entity;
-        }
-
-        /// <inheritdoc />
-        public bool Match(IEntity entity)
-        {
-            if(Entity.TryGetComponent<IPhysBody>(out var physics))
-            {
-                return physics.Owner.Transform.MapID == entity.Transform.MapID && physics.GetWorldAABB().Contains(entity.Transform.WorldPosition);
-            }
-            return false;
-        }
-
-        public IEnumerable<IEntity> Match(IEntityManager entityMan)
-        {
-            return entityMan.GetEntities().Where(entity => Match(entity));
-        }
-    }
-
-    /// <summary>
-    ///     An entity query that will match entities that have all of the provided components.
-    /// </summary>
-    [PublicAPI, Obsolete]
-    public class MultipleTypeEntityQuery : IEntityQuery
-    {
-        private readonly List<Type> ComponentTypes;
-
-        /// <summary>
-        ///     Constructs a new instance of <c>MultipleTypeEntityQuery</c>.
-        /// </summary>
-        /// <param name="componentTypes">List of component types to match.</param>
-        public MultipleTypeEntityQuery(List<Type> componentTypes)
-        {
-            foreach (var componentType in componentTypes)
-            {
-                DebugTools.Assert(typeof(IComponent).IsAssignableFrom(componentType), "componentType must inherit IComponent");
-            }
-
-            ComponentTypes = componentTypes;
-        }
-
-        /// <inheritdoc />
-        public bool Match(IEntity entity)
-        {
-            foreach (var componentType in ComponentTypes)
-            {
-                if (!entity.HasComponent(componentType))
-                {
-                    return false;
-                }
-            }
-            return true;
-        }
-
-        /// <inheritdoc />
-        public IEnumerable<IEntity> Match(IEntityManager entityMan)
-        {
-            return entityMan.GetEntities(new TypeEntityQuery(ComponentTypes.First())).Where(entity => Match(entity));
-        }
-    }
-}

Robust.Shared/GameObjects/EntitySystem.Subscriptions.cs

@@ -7,16 +7,22 @@ namespace Robust.Shared.GameObjects
     {
         private List<SubBase>? _subscriptions;
 
-        protected void SubscribeNetworkEvent<T>(EntityEventHandler<T> handler)
+        // NOTE: EntityEventHandler<T> and EntitySessionEventHandler<T> CANNOT BE ORDERED BETWEEN EACH OTHER.
+
+        protected void SubscribeNetworkEvent<T>(
+            EntityEventHandler<T> handler,
+            Type[]? before=null, Type[]? after=null)
             where T : notnull
         {
-            EntityManager.EventBus.SubscribeEvent(EventSource.Network, this, handler);
+            EntityManager.EventBus.SubscribeEvent(EventSource.Network, this, handler, GetType(), before, after);
 
             _subscriptions ??= new();
             _subscriptions.Add(new SubBroadcast<T>(EventSource.Network));
         }
 
-        protected void SubscribeNetworkEvent<T>(EntitySessionEventHandler<T> handler)
+        protected void SubscribeNetworkEvent<T>(
+            EntitySessionEventHandler<T> handler,
+            Type[]? before=null, Type[]? after=null)
             where T : notnull
         {
             EntityManager.EventBus.SubscribeSessionEvent(EventSource.Network, this, handler);
@@ -25,16 +31,20 @@ namespace Robust.Shared.GameObjects
             _subscriptions.Add(new SubBroadcast<EntitySessionMessage<T>>(EventSource.Network));
         }
 
-        protected void SubscribeLocalEvent<T>(EntityEventHandler<T> handler)
+        protected void SubscribeLocalEvent<T>(
+            EntityEventHandler<T> handler,
+            Type[]? before=null, Type[]? after=null)
             where T : notnull
         {
-            EntityManager.EventBus.SubscribeEvent(EventSource.Local, this, handler);
+            EntityManager.EventBus.SubscribeEvent(EventSource.Local, this, handler, GetType(), before, after);
 
             _subscriptions ??= new();
             _subscriptions.Add(new SubBroadcast<T>(EventSource.Local));
         }
 
-        protected void SubscribeLocalEvent<T>(EntitySessionEventHandler<T> handler)
+        protected void SubscribeLocalEvent<T>(
+            EntitySessionEventHandler<T> handler,
+            Type[]? before=null, Type[]? after=null)
             where T : notnull
         {
             EntityManager.EventBus.SubscribeSessionEvent(EventSource.Local, this, handler);
@@ -57,8 +67,9 @@ namespace Robust.Shared.GameObjects
             EntityManager.EventBus.UnsubscribeEvent<T>(EventSource.Local, this);
         }
 
-
-        protected void SubscribeLocalEvent<TComp, TEvent>(ComponentEventHandler<TComp, TEvent> handler)
+        protected void SubscribeLocalEvent<TComp, TEvent>(
+            ComponentEventHandler<TComp, TEvent> handler,
+            Type[]? before=null, Type[]? after=null)
             where TComp : IComponent
             where TEvent : EntityEventArgs
         {

Robust.Shared/GameObjects/EntitySystemManager.cs

@@ -114,7 +114,7 @@ namespace Robust.Shared.GameObjects
             {
                 Logger.DebugS("go.sys", "Initializing entity system {0}", type);
                 // Force IoC inject of all systems
-                var instance = _typeFactory.CreateInstanceUnchecked<IEntitySystem>(type);
+                var instance = _typeFactory.CreateInstanceUnchecked<IEntitySystem>(type, oneOff: true);
 
                 _systems.Add(type, instance);
 
@@ -166,15 +166,15 @@ namespace Robust.Shared.GameObjects
                 Dictionary<Type, IEntitySystem>.ValueCollection systems,
                 Dictionary<Type, IEntitySystem> supertypeSystems)
         {
-            var allNodes = new List<GraphNode<IEntitySystem>>();
-            var typeToNode = new Dictionary<Type, GraphNode<IEntitySystem>>();
+            var allNodes = new List<TopologicalSort.GraphNode<IEntitySystem>>();
+            var typeToNode = new Dictionary<Type, TopologicalSort.GraphNode<IEntitySystem>>();
 
             foreach (var system in systems)
             {
-                var node = new GraphNode<IEntitySystem>(system);
+                var node = new TopologicalSort.GraphNode<IEntitySystem>(system);
 
-                allNodes.Add(node);
                 typeToNode.Add(system.GetType(), node);
+                allNodes.Add(node);
             }
 
             foreach (var (type, system) in supertypeSystems)
@@ -183,52 +183,30 @@ namespace Robust.Shared.GameObjects
                 typeToNode[type] = node;
             }
 
-            foreach (var node in allNodes)
+            foreach (var node in typeToNode.Values)
             {
-                foreach (var after in node.System.UpdatesAfter)
+                foreach (var after in node.Value.UpdatesAfter)
                 {
                     var system = typeToNode[after];
 
-                    node.DependsOn.Add(system);
+                    system.Dependant.Add(node);
                 }
 
-                foreach (var before in node.System.UpdatesBefore)
+                foreach (var before in node.Value.UpdatesBefore)
                 {
                     var system = typeToNode[before];
 
-                    system.DependsOn.Add(node);
+                    node.Dependant.Add(system);
                 }
             }
 
-            var order = TopologicalSort(allNodes).Select(p => p.System).ToArray();
+            var order = TopologicalSort.Sort(allNodes).ToArray();
             var frameUpdate = order.Where(p => NeedsFrameUpdate(p.GetType()));
             var update = order.Where(p => NeedsUpdate(p.GetType()));
 
             return (frameUpdate, update);
         }
 
-        internal static IEnumerable<GraphNode<T>> TopologicalSort<T>(IEnumerable<GraphNode<T>> nodes)
-        {
-            var elems = nodes.ToDictionary(node => node,
-                node => new HashSet<GraphNode<T>>(node.DependsOn));
-            while (elems.Count > 0)
-            {
-                var elem =
-                    elems.FirstOrDefault(x => x.Value.Count == 0);
-                if (elem.Key == null)
-                {
-                    throw new InvalidOperationException(
-                        "Found circular dependency when resolving entity system update dependency graph");
-                }
-                elems.Remove(elem.Key);
-                foreach (var selem in elems)
-                {
-                    selem.Value.Remove(elem.Key);
-                }
-                yield return elem.Key;
-            }
-        }
-
         private static IEnumerable<Type> GetBaseTypes(Type type) {
             if(type.BaseType == null) return type.GetInterfaces();
 
@@ -344,18 +322,6 @@ namespace Robust.Shared.GameObjects
             return mFrameUpdate!.DeclaringType != typeof(EntitySystem);
         }
 
-        [DebuggerDisplay("GraphNode: {" + nameof(System) + "}")]
-        internal sealed class GraphNode<T>
-        {
-            public readonly T System;
-            public readonly List<GraphNode<T>> DependsOn = new();
-
-            public GraphNode(T system)
-            {
-                System = system;
-            }
-        }
-
         private struct UpdateReg
         {
             [ViewVariables] public IEntitySystem System;