Version: 246.0.3

Also, only read assemblies once from disk

(cherry picked from commit 443a8dfca65be7d60c4bd46181b4c749b4756114)

Directory.Packages.props

@@ -57,7 +57,7 @@
     <PackageVersion Include="SharpZstd.Interop" Version="1.5.2-beta2" />
     <PackageVersion Include="SixLabors.ImageSharp" Version="3.1.6" />
     <PackageVersion Include="SpaceWizards.HttpListener" Version="0.1.1" />
-    <PackageVersion Include="SpaceWizards.NFluidsynth" Version="0.1.1" />
+    <PackageVersion Include="SpaceWizards.NFluidsynth" Version="0.2.2" />
     <PackageVersion Include="SpaceWizards.SharpFont" Version="1.0.2" />
     <PackageVersion Include="SpaceWizards.Sodium" Version="0.2.1" />
     <PackageVersion Include="TerraFX.Interop.Windows" Version="10.0.26100.1" />

MSBuild/Robust.Engine.Version.props

@@ -1,4 +1,4 @@
 <Project>
 
-    <!-- This file automatically reset by Tools/version.py -->
+    <!-- This file automatically reset by Tools/version.py -->
 

RELEASE-NOTES.md

@@ -54,10 +54,159 @@ END TEMPLATE-->
 *None yet*
 
 
-## 240.1.3-source-gen-debug
+## 246.0.3
 
 
-## 240.1.2-source-gen-debug
+## 246.0.2
+
+
+## 246.0.1
+
+
+## 246.0.0
+
+### Breaking changes
+
+* The fixes to renderer state may have inadvertantly broken some rendering code that relied upon the old behavior.
+* TileRenderFlag has been removed and now it's just a byte flag on the tile for content usage.
+
+### New features
+
+* Add BeforeLighting overlay draw space for overlays that need to draw directly to lighting and want to do it immediately beforehand.
+* Change BlurLights to BlurRenderTarget and make it public for content usage.
+* Add ContentFlag to tiles for content-flag usage.
+* Add a basic mix shader for doing canvas blends.
+* Add GetClearColorEvent for content to override the clear color behavior.
+
+### Bugfixes
+
+* Fix pushing renderer state not restoring stencil status, blend status, queued shader instance scissor state.
+
+
+## 245.1.0
+
+### New features
+
+* Add more info to the AnchorEntity debug message.
+* Make ParseObject public where it will parse a supplied Type and string into the specified object.
+
+### Bugfixes
+
+* Fix EntityPrototypeView not always updating the entity correctly.
+* Tweak BUI shutdown to potentially avoid skipping closing.
+
+### Other
+
+* Increase Audio entity despawn buffer to avoid clipping.
+
+
+## 245.0.0
+
+### Breaking changes
+
+* `BoundUserInterface.Open()` now has the `MustCallBase` attribute
+
+### Bugfixes
+
+* Fixed an error in `MappingDataNode.TryAddCopy()`, which was causing yaml inheritance/deserialization bugs.
+
+
+## 244.0.0
+
+### Breaking changes
+
+* Increase physics speedcap default from 35m/s to 400m/s in-line with box2d v3.
+
+### New features
+
+* Add EntityManager overloads for ComponentRegistration that's faster than the generic methods.
+* Add CreateWindowCenteredRight for BUIs.
+
+### Bugfixes
+
+* Avoid calling UpdateState before opening a BUI.
+
+
+## 243.0.1
+
+### Bugfixes
+
+* Fixed `BaseWindow` sometimes not properly updating the mouse cursor shape.
+* Revert `BaseWindow` OnClose ordering due to prior reliance upon the ordering.
+
+
+## 243.0.0
+
+### Breaking changes
+
+* RemoveChild is called after OnClose for BaseWindow.
+
+### New features
+
+* BUIs now have their positions saved when closed and re-used when opened when using the `CreateWindow<T>` helper or via manually registering it via RegisterControl.
+
+### Other
+
+* Ensure grid fixtures get updated in client state handling even if exceptions occur.
+
+
+## 242.0.1
+
+### Bugfixes
+
+* Fixed prototype reloading/hotloading not properly handling data-fields with the `AlwaysPushInheritanceAttribute`
+* Fix the pooled polygons using incorrect vertices for EntityLookup and MapManager.
+
+### Internal
+
+* Avoid normalizing angles constructed from vectors.
+
+
+## 242.0.0
+
+### Breaking changes
+
+* The order in which the client initialises networked entities has changed. It will now always apply component states, initialise, and start an entity's parent before processing any children. This might break anything that was relying on the old behaviour where all component states were applied before any entities were initialised & started.
+* `IClydeViewport` overlay rendering methods now take in an `IRenderHandle` instead of a world/screen handle.
+* The `OverlayDrawArgs` struct now has an internal constructor.
+
+### New features
+
+* Controls can now be manually restyled via `Control.InvalidateStyleSheet()` and `Control.DoStyleUpdate()`
+* Added `IUserInterfaceManager.RenderControl()` for manually drawing controls.
+* `OverlayDrawArgs` struct now has an `IRenderHandle` field such that overlays can use the new `RenderControl()` methods.
+* TileSpawnWindow will now take focus when opened.
+
+### Bugfixes
+
+* Fixed a client-side bug where `TransformComponent.GridUid` does not get set properly when an existing entity is attached to a new entity outside of the player's PVS range.
+* EntityPrototypeView will only create entities when it's on the UI tree and not when the prototype is set.
+* Make CollisionWake not log errors if it can't resolve.
+
+### Other
+
+* Replace IPhysShape API with generics on IMapManager and EntityLookupSystem.
+
+### Internal
+
+* Significantly reduce allocations for Box2 / Box2Rotated queries.
+
+
+## 241.0.0
+
+### Breaking changes
+
+* Remove DeferredClose from BUIs.
+
+### New features
+
+* Added `EntityManager.DirtyFields()`, which allows components with delta states to simultaneously mark several fields as dirty at the same time.
+* Add `CloserUserUIs<T>` to close keys of a specific key.
+
+### Bugfixes
+
+* Fixed `RaisePredictiveEvent()` not properly re-raising events during prediction for event handlers that did not take an `EntitySessionEventArgs` argument.
+* BUI openings are now deferred to avoid having slight desync between deferred closes and opens occurring in the same tick.
 
 
 ## 240.1.2

Resources/EnginePrototypes/Shaders/stockshaders.yml

@@ -4,6 +4,12 @@
   kind: canvas
   light_mode: unshaded
 
+# Simple mix blend
+- type: shader
+  id: Mix
+  kind: canvas
+  blend_mode: Mix
+
 - type: shader
   id: shaded
   kind: canvas

Robust.Benchmarks/EntityManager/HasComponentBenchmark.cs

@@ -0,0 +1,96 @@
+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Engines;
+using JetBrains.Annotations;
+using Robust.Shared.Analyzers;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Map;
+using Robust.UnitTesting.Server;
+
+namespace Robust.Benchmarks.EntityManager;
+
+[Virtual]
+public partial class HasComponentBenchmark
+{
+    private static readonly Consumer Consumer = new();
+
+    private ISimulation _simulation = default!;
+    private IEntityManager _entityManager = default!;
+
+    private ComponentRegistration _compReg = default!;
+
+    private A _dummyA = new();
+
+    [UsedImplicitly]
+    [Params(1, 10, 100, 1000)]
+    public int N;
+
+    [GlobalSetup]
+    public void GlobalSetup()
+    {
+        _simulation = RobustServerSimulation
+            .NewSimulation()
+            .RegisterComponents(f => f.RegisterClass<A>())
+            .InitializeInstance();
+
+        _entityManager = _simulation.Resolve<IEntityManager>();
+        var map = _simulation.CreateMap().Uid;
+        var coords = new EntityCoordinates(map, default);
+        _compReg = _entityManager.ComponentFactory.GetRegistration(typeof(A));
+
+        for (var i = 0; i < N; i++)
+        {
+            var uid = _entityManager.SpawnEntity(null, coords);
+            _entityManager.AddComponent<A>(uid);
+        }
+    }
+
+    [Benchmark]
+    public void HasComponentGeneric()
+    {
+        for (var i = 2; i <= N+1; i++)
+        {
+            var uid = new EntityUid(i);
+            var result = _entityManager.HasComponent<A>(uid);
+            Consumer.Consume(result);
+        }
+    }
+
+    [Benchmark]
+    public void HasComponentCompReg()
+    {
+        for (var i = 2; i <= N+1; i++)
+        {
+            var uid = new EntityUid(i);
+            var result = _entityManager.HasComponent(uid, _compReg);
+            Consumer.Consume(result);
+        }
+    }
+
+    [Benchmark]
+    public void HasComponentType()
+    {
+        for (var i = 2; i <= N+1; i++)
+        {
+            var uid = new EntityUid(i);
+            var result = _entityManager.HasComponent(uid, typeof(A));
+            Consumer.Consume(result);
+        }
+    }
+
+    [Benchmark]
+    public void HasComponentGetType()
+    {
+        for (var i = 2; i <= N+1; i++)
+        {
+            var uid = new EntityUid(i);
+            var type = _dummyA.GetType();
+            var result = _entityManager.HasComponent(uid, type);
+            Consumer.Consume(result);
+        }
+    }
+
+    [ComponentProtoName("A")]
+    public sealed partial class A : Component
+    {
+    }
+}

Robust.Client.WebView/Cef/Program.cs

@@ -6,7 +6,7 @@ using Xilium.CefGlue;
 
 namespace Robust.Client.WebView.Cef
 {
-    public static class Program
+    internal static class Program
     {
         // This was supposed to be the main entry for the subprocess program... It doesn't work.
         public static int Main(string[] args)

Robust.Client.WebView/Cef/WebViewManagerCef.cs

@@ -5,6 +5,7 @@ using System.Net;
 using System.Reflection;
 using System.Text;
 using Robust.Client.Console;
+using Robust.Client.Utility;
 using Robust.Shared.Configuration;
 using Robust.Shared.ContentPack;
 using Robust.Shared.IoC;
@@ -24,6 +25,7 @@ namespace Robust.Client.WebView.Cef
 
         [Dependency] private readonly IDependencyCollection _dependencyCollection = default!;
         [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
+        [Dependency] private readonly IGameControllerInternal _gameController = default!;
         [Dependency] private readonly IResourceManagerInternal _resourceManager = default!;
         [Dependency] private readonly IClientConsoleHost _consoleHost = default!;
         [Dependency] private readonly IConfigurationManager _cfg = default!;
@@ -61,7 +63,10 @@ namespace Robust.Client.WebView.Cef
 
             var cachePath = "";
             if (_resourceManager.UserData is WritableDirProvider userData)
-                cachePath = userData.GetFullPath(new ResPath("/cef_cache"));
+            {
+                var rootDir = UserDataDir.GetRootUserDataDir(_gameController);
+                cachePath = Path.Combine(rootDir, "cef_cache", "0");
+            }
 
             var settings = new CefSettings()
             {

Robust.Client/GameController/GameController.cs

@@ -382,7 +382,7 @@ namespace Robust.Client
 
             _prof.Initialize();
 
-            _resManager.Initialize(Options.LoadConfigAndUserData ? userDataDir : null);
+            _resManager.Initialize(Options.LoadConfigAndUserData ? userDataDir : null, hideUserDataDir: true);
 
             var mountOptions = _commandLineArgs != null
                 ? MountOptions.Merge(_commandLineArgs.MountOptions, Options.MountOptions)

Robust.Client/GameObjects/ClientEntityManager.cs

@@ -101,11 +101,33 @@ namespace Robust.Client.GameObjects
         /// <inheritdoc />
         public override void Dirty<T>(Entity<T> ent, MetaDataComponent? meta = null)
         {
-            //  Client only dirties during prediction
+            // Client only dirties during prediction
             if (_gameTiming.InPrediction)
                 base.Dirty(ent, meta);
         }
 
+        public override void DirtyField<T>(EntityUid uid, T comp, string fieldName, MetaDataComponent? metadata = null)
+        {
+            // TODO Prediction
+            // does the client actually need to dirty the field?
+            // I.e., can't it just dirty the whole component to trigger a reset?
+
+            // Client only dirties during prediction
+            if (_gameTiming.InPrediction)
+                base.DirtyField(uid, comp, fieldName, metadata);
+        }
+
+        public override void DirtyFields<T>(EntityUid uid, T comp, MetaDataComponent? meta, params ReadOnlySpan<string> fields)
+        {
+            // TODO Prediction
+            // does the client actually need to dirty the field?
+            // I.e., can't it just dirty the whole component to trigger a reset?
+
+            // Client only dirties during prediction
+            if (_gameTiming.InPrediction)
+                base.DirtyFields(uid, comp, meta, fields);
+        }
+
         /// <inheritdoc />
         public override void Dirty<T1, T2>(Entity<T1, T2> ent, MetaDataComponent? meta = null)
         {

Robust.Client/GameObjects/EntitySystems/UserInterfaceSystem.cs

@@ -1,10 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Numerics;
+using Robust.Client.UserInterface;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Prototypes;
+using Robust.Shared.Utility;
 
 namespace Robust.Client.GameObjects;
 
 public sealed class UserInterfaceSystem : SharedUserInterfaceSystem
 {
+    private Dictionary<EntityUid, Dictionary<Enum, Vector2>> _savedPositions = new();
+    private Dictionary<BoundUserInterface, Control> _registeredControls = new();
+
     public override void Initialize()
     {
         base.Initialize();
@@ -17,6 +25,59 @@ public sealed class UserInterfaceSystem : SharedUserInterfaceSystem
         ProtoManager.PrototypesReloaded -= OnProtoReload;
     }
 
+    protected override void OnUserInterfaceShutdown(Entity<UserInterfaceComponent> ent, ref ComponentShutdown args)
+    {
+        base.OnUserInterfaceShutdown(ent, ref args);
+        _savedPositions.Remove(ent.Owner);
+    }
+
+    /// <inheritdoc />
+    public override void OpenUi(Entity<UserInterfaceComponent?> entity, Enum key, bool predicted = false)
+    {
+        var player = Player.LocalEntity;
+
+        if (player == null)
+            return;
+
+        OpenUi(entity, key, player.Value, predicted);
+    }
+
+    protected override void SavePosition(BoundUserInterface bui)
+    {
+        if (!_registeredControls.Remove(bui, out var control))
+            return;
+
+        var keyed = _savedPositions[bui.Owner];
+        keyed[bui.UiKey] = control.Position;
+    }
+
+    /// <summary>
+    /// Registers a control so it will later have its position stored by <see cref="SavePosition"/> when the BUI is closed.
+    /// </summary>
+    public void RegisterControl(BoundUserInterface bui, Control control)
+    {
+        DebugTools.Assert(!_registeredControls.ContainsKey(bui));
+        _registeredControls[bui] = control;
+        _savedPositions.GetOrNew(bui.Owner);
+    }
+
+    public override bool TryGetPosition(Entity<UserInterfaceComponent?> entity, Enum key, out Vector2 position)
+    {
+        position = default;
+
+        if (!_savedPositions.TryGetValue(entity.Owner, out var keyed))
+        {
+            return false;
+        }
+
+        if (!keyed.TryGetValue(key, out position))
+        {
+            return false;
+        }
+
+        return true;
+    }
+
     private void OnProtoReload(PrototypesReloadedEventArgs obj)
     {
         var player = Player.LocalEntity;

Robust.Client/GameStates/ClientGameStateManager.cs

@@ -23,7 +23,6 @@ using Robust.Shared.Input;
 using Robust.Shared.IoC;
 using Robust.Shared.Localization;
 using Robust.Shared.Log;
-using Robust.Shared.Map;
 using Robust.Shared.Network;
 using Robust.Shared.Network.Messages;
 using Robust.Shared.Profiling;
@@ -42,13 +41,13 @@ namespace Robust.Client.GameStates
         private uint _nextInputCmdSeq = 1;
         private readonly Queue<FullInputCmdMessage> _pendingInputs = new();
 
-        private readonly Queue<(uint sequence, GameTick sourceTick, EntityEventArgs msg, object sessionMsg)>
+        private readonly Queue<(uint sequence, GameTick sourceTick, object msg, object sessionMsg)>
             _pendingSystemMessages
                 = new();
 
         // Game state dictionaries that get used every tick.
-        private readonly Dictionary<EntityUid, (NetEntity NetEntity, MetaDataComponent Meta, bool EnteringPvs, GameTick LastApplied, EntityState? curState, EntityState? nextState)> _toApply = new();
-        private readonly Dictionary<NetEntity, EntityState> _toCreate = new();
+        private readonly Dictionary<EntityUid, StateData> _toApply = new();
+        private StateData[] _toApplySorted = default!;
         private readonly Dictionary<ushort, (IComponent Component, IComponentState? curState, IComponentState? nextState)> _compStateWork = new();
         private readonly Dictionary<EntityUid, HashSet<Type>> _pendingReapplyNetStates = new();
         private readonly HashSet<NetEntity> _stateEnts = new();
@@ -56,15 +55,29 @@ namespace Robust.Client.GameStates
         private readonly List<IComponent> _toRemove = new();
         private readonly Dictionary<NetEntity, Dictionary<ushort, IComponentState?>> _outputData = new();
         private readonly List<(EntityUid, TransformComponent)> _queuedBroadphaseUpdates = new();
+        private readonly HashSet<EntityUid> _sorted = new();
+        private readonly List<NetEntity> _created = new();
+        private readonly List<NetEntity> _detached = new();
+
+        private readonly record struct StateData(
+            EntityUid Uid,
+            NetEntity NetEntity,
+            MetaDataComponent Meta,
+            bool Created,
+            bool EnteringPvs,
+            GameTick LastApplied,
+            EntityState? CurState,
+            EntityState? NextState,
+            HashSet<Type>? PendingReapply);
 
         private readonly ObjectPool<Dictionary<ushort, IComponentState?>> _compDataPool =
             new DefaultObjectPool<Dictionary<ushort, IComponentState?>>(new DictPolicy<ushort, IComponentState?>(), 256);
 
         private uint _metaCompNetId;
+        private uint _xformCompNetId;
 
         [Dependency] private readonly IReplayRecordingManager _replayRecording = default!;
         [Dependency] private readonly IComponentFactory _compFactory = default!;
-        [Dependency] private readonly IClientEntityManagerInternal _entities = default!;
         [Dependency] private readonly IPlayerManager _players = default!;
         [Dependency] private readonly IClientNetManager _network = default!;
         [Dependency] private readonly IBaseClient _client = default!;
@@ -72,7 +85,7 @@ namespace Robust.Client.GameStates
         [Dependency] private readonly INetConfigurationManager _config = default!;
         [Dependency] private readonly IEntitySystemManager _entitySystemManager = default!;
         [Dependency] private readonly IConsoleHost _conHost = default!;
-        [Dependency] private readonly ClientEntityManager _entityManager = default!;
+        [Dependency] private readonly ClientEntityManager _entities = default!;
         [Dependency] private readonly IInputManager _inputManager = default!;
         [Dependency] private readonly ProfManager _prof = default!;
         [Dependency] private readonly IRuntimeLog _runtimeLog = default!;
@@ -126,7 +139,6 @@ namespace Robust.Client.GameStates
 
         private bool _resettingPredictedEntities;
         private readonly List<EntityUid> _brokenEnts = new();
-        private readonly List<(EntityUid, NetEntity)> _toStart = new();
 
         /// <inheritdoc />
         public void Initialize()
@@ -172,6 +184,12 @@ namespace Robust.Client.GameStates
                 throw new InvalidOperationException("MetaDataComponent does not have a NetId.");
 
             _metaCompNetId = metaId.Value;
+
+            var xformId = _compFactory.GetRegistration(typeof(TransformComponent)).NetID;
+            if (!xformId.HasValue)
+                throw new InvalidOperationException("TransformComponent does not have a NetId.");
+
+            _xformCompNetId = xformId.Value;
         }
 
         private void OnComponentAdded(AddedComponentEventArgs args)
@@ -183,11 +201,11 @@ namespace Robust.Client.GameStates
             if (comp.NetID == null)
                 return;
 
-            if (_entityManager.IsClientSide(args.BaseArgs.Owner))
+            if (_entities.IsClientSide(args.BaseArgs.Owner))
                 return;
 
             _sawmill.Error($"""
-                Added component {comp.Name} to entity {_entityManager.ToPrettyString(args.BaseArgs.Owner)} while resetting predicted entities.
+                Added component {comp.Name} to entity {_entities.ToPrettyString(args.BaseArgs.Owner)} while resetting predicted entities.
                 Stack trace:
                 {Environment.StackTrace}
                 """);
@@ -385,7 +403,7 @@ namespace Robust.Client.GameStates
                     try
                     {
 #endif
-                    createdEntities = ApplyGameState(curState, nextState);
+                    ApplyGameState(curState, nextState);
 #if EXCEPTION_TOLERANCE
                     }
                     catch (MissingMetadataException e)
@@ -399,7 +417,7 @@ namespace Robust.Client.GameStates
 
                 using (_prof.Group("MergeImplicitData"))
                 {
-                    GenerateImplicitStates(createdEntities);
+                    MergeImplicitData();
                 }
 
                 if (_lastProcessedInput < curState.LastProcessedInput)
@@ -456,7 +474,7 @@ namespace Robust.Client.GameStates
 
             using (_prof.Group("Tick"))
             {
-                _entities.TickUpdate((float) _timing.TickPeriod.TotalSeconds, noPredictions: !IsPredictionEnabled);
+                _entities.TickUpdate((float) _timing.TickPeriod.TotalSeconds, noPredictions: !IsPredictionEnabled, histogram: null);
             }
         }
 
@@ -504,9 +522,7 @@ namespace Robust.Client.GameStates
 
                 while (hasPendingMessage && pendingMessagesEnumerator.Current.sourceTick <= _timing.CurTick)
                 {
-                    var msg = pendingMessagesEnumerator.Current.msg;
-
-                    _entities.EventBus.RaiseEvent(EventSource.Local, msg);
+                    _entities.EventBus.RaiseEvent(EventSource.Local, pendingMessagesEnumerator.Current.msg);
                     _entities.EventBus.RaiseEvent(EventSource.Local, pendingMessagesEnumerator.Current.sessionMsg);
                     hasPendingMessage = pendingMessagesEnumerator.MoveNext();
                 }
@@ -545,7 +561,7 @@ namespace Robust.Client.GameStates
             PredictionNeedsResetting = false;
             var countReset = 0;
             var system = _entitySystemManager.GetEntitySystem<ClientDirtySystem>();
-            var metaQuery = _entityManager.GetEntityQuery<MetaDataComponent>();
+            var metaQuery = _entities.GetEntityQuery<MetaDataComponent>();
             RemQueue<IComponent> toRemove = new();
 
             foreach (var entity in system.DirtyEntities)
@@ -632,7 +648,7 @@ namespace Robust.Client.GameStates
                         if (!last.TryGetValue(netId, out var state))
                             continue;
 
-                        var comp = _entityManager.AddComponent(entity, netId, meta);
+                        var comp = _entities.AddComponent(entity, netId, meta);
 
                         if (_sawmill.Level <= LogLevel.Debug)
                             _sawmill.Debug($"  A component was removed: {comp.GetType()}");
@@ -652,7 +668,7 @@ namespace Robust.Client.GameStates
                 meta.EntityLastModifiedTick = _timing.LastRealTick;
             }
 
-            _entityManager.System<PhysicsSystem>().ResetContacts();
+            _entities.System<PhysicsSystem>().ResetContacts();
 
             // TODO maybe reset more of physics?
             // E.g., warm impulses for warm starting?
@@ -671,21 +687,21 @@ namespace Robust.Client.GameStates
         ///     initial server state for any newly created entity. It does this by simply using the standard <see
         ///     cref="IEntityManager.GetComponentState"/>.
         /// </remarks>
-        public void GenerateImplicitStates(IEnumerable<NetEntity> createdEntities)
+        public void MergeImplicitData()
         {
-            var bus = _entityManager.EventBus;
+            var bus = _entities.EventBus;
 
-            foreach (var netEntity in createdEntities)
+            foreach (var netEntity in _created)
             {
-#if EXCEPTION_TOLERANCE
-                if (!_entityManager.TryGetEntityData(netEntity, out _, out var meta))
+                if (!_entities.TryGetEntityData(netEntity, out _, out var meta))
                 {
                     _sawmill.Error($"Encountered deleted entity while merging implicit data! NetEntity: {netEntity}");
+
+#if !EXCEPTION_TOLERANCE
+                    throw new KeyNotFoundException();
+#endif
                     continue;
                 }
-#else
-                var (_, meta) = _entityManager.GetEntityData(netEntity);
-#endif
 
                 var compData = _compDataPool.Get();
                 _outputData.Add(netEntity, compData);
@@ -694,12 +710,13 @@ namespace Robust.Client.GameStates
                 {
                     DebugTools.Assert(component.NetSyncEnabled);
 
-                    var state = _entityManager.GetComponentState(bus, component, null, GameTick.Zero);
+                    var state = _entities.GetComponentState(bus, component, null, GameTick.Zero);
                     DebugTools.Assert(state is not IComponentDeltaState);
                     compData.Add(netId, state);
                 }
             }
 
+            _created.Clear();
             _processor.MergeImplicitData(_outputData);
 
             foreach (var data in _outputData.Values)
@@ -735,10 +752,9 @@ namespace Robust.Client.GameStates
                 _config.TickProcessMessages();
             }
 
-            (IEnumerable<NetEntity> Created, List<NetEntity> Detached) output;
             using (_prof.Group("Entity"))
             {
-                output = ApplyEntityStates(curState, nextState);
+                ApplyEntityStates(curState, nextState);
             }
 
             using (_prof.Group("Player"))
@@ -748,13 +764,13 @@ namespace Robust.Client.GameStates
 
             using (_prof.Group("Callback"))
             {
-                GameStateApplied?.Invoke(new GameStateAppliedArgs(curState, output.Detached));
+                GameStateApplied?.Invoke(new GameStateAppliedArgs(curState, _detached));
             }
 
-            return output.Created;
+            return _created;
         }
 
-        private (IEnumerable<NetEntity> Created, List<NetEntity> Detached) ApplyEntityStates(GameState curState, GameState? nextState)
+        private void ApplyEntityStates(GameState curState, GameState? nextState)
         {
             var metas = _entities.GetEntityQuery<MetaDataComponent>();
             var xforms = _entities.GetEntityQuery<TransformComponent>();
@@ -762,90 +778,74 @@ namespace Robust.Client.GameStates
 
             var enteringPvs = 0;
             _toApply.Clear();
-            _toCreate.Clear();
+            _created.Clear();
             _pendingReapplyNetStates.Clear();
             var curSpan = curState.EntityStates.Span;
 
             // Create new entities
             // This is done BEFORE state application to ensure any new parents exist before existing children have their states applied, otherwise, we may have issues with entity transforms!
-            {
-                using var _ = _prof.Group("Create uninitialized entities");
-                var count = 0;
 
+            using (_prof.Group("Create uninitialized entities"))
+            {
+                var created = 0;
                 foreach (var es in curSpan)
                 {
-                    if (_entityManager.TryGetEntity(es.NetEntity, out var nUid))
+                    if (_entities.TryGetEntity(es.NetEntity, out var nUid))
                     {
-                        DebugTools.Assert(_entityManager.EntityExists(nUid));
+                        DebugTools.Assert(_entities.EntityExists(nUid));
                         continue;
                     }
 
-                    count++;
-                    var metaState = (MetaDataComponentState?)es.ComponentChanges.Value?.FirstOrDefault(c => c.NetID == _metaCompNetId).State;
-                    if (metaState == null)
-                        throw new MissingMetadataException(es.NetEntity);
-
-                    var uid = _entities.CreateEntity(metaState.PrototypeId, out var newMeta);
-                    _toCreate.Add(es.NetEntity, es);
-                    _toApply.Add(uid, (es.NetEntity, newMeta, false, GameTick.Zero, es, null));
-
-                    // Client creates a client-side net entity for the newly created entity.
-                    // We need to clear this mapping before assigning the real net id.
-                    // TODO NetEntity Jank: prevent the client from creating this in the first place.
-                    _entityManager.ClearNetEntity(newMeta.NetEntity);
-
-                    _entityManager.SetNetEntity(uid, es.NetEntity, newMeta);
-                    newMeta.LastStateApplied = curState.ToSequence;
-
-                    // Check if there's any component states awaiting this entity.
-                    if (_entityManager.PendingNetEntityStates.Remove(es.NetEntity, out var value))
-                    {
-                        foreach (var (type, owner) in value)
-                        {
-                            var pending = _pendingReapplyNetStates.GetOrNew(owner);
-                            pending.Add(type);
-                        }
-                    }
+                    created++;
+                    CreateNewEntity(es, curState.ToSequence);
                 }
 
-                _prof.WriteValue("Count", ProfData.Int32(count));
+                _prof.WriteValue("Count", ProfData.Int32(created));
             }
 
+            // Add entity entities that aren't new to _toCreate.
+            // In the process, we also check if these entities are re-entering PVS range.
             foreach (var es in curSpan)
             {
-                if (_toCreate.ContainsKey(es.NetEntity))
+                if (!_entities.TryGetEntityData(es.NetEntity, out var uid, out var meta))
                     continue;
 
-                if (!_entityManager.TryGetEntityData(es.NetEntity, out var uid, out var meta))
-                    continue;
-
-                bool isEnteringPvs = (meta.Flags & MetaDataFlags.Detached) != 0;
+                var isEnteringPvs = (meta.Flags & MetaDataFlags.Detached) != 0;
                 if (isEnteringPvs)
                 {
+                    // _toApply already contains newly created entities, but these should never be "entering PVS"
+                    DebugTools.Assert(!_toApply.ContainsKey(uid.Value));
+
                     meta.Flags &= ~MetaDataFlags.Detached;
                     enteringPvs++;
                 }
                 else if (meta.LastStateApplied >= es.EntityLastModified && meta.LastStateApplied != GameTick.Zero)
                 {
+                    // _toApply already contains newly created entities, but for those this set should have no effect
+                    DebugTools.Assert(!_toApply.ContainsKey(uid.Value) || meta.LastStateApplied == curState.ToSequence);
+
                     meta.LastStateApplied = curState.ToSequence;
                     continue;
                 }
 
-                _toApply.Add(uid.Value, (es.NetEntity, meta, isEnteringPvs, meta.LastStateApplied, es, null));
+                // Any newly created entities already added to _toApply should've already been caught by the previous continue
+                DebugTools.Assert(!_toApply.ContainsKey(uid.Value));
+
+                _toApply.Add(uid.Value, new(uid.Value, es.NetEntity, meta, false, isEnteringPvs, meta.LastStateApplied, es, null, null));
                 meta.LastStateApplied = curState.ToSequence;
             }
 
             // Detach entities to null space
             var containerSys = _entitySystemManager.GetEntitySystem<ContainerSystem>();
             var lookupSys = _entitySystemManager.GetEntitySystem<EntityLookupSystem>();
-            var detached = ProcessPvsDeparture(curState.ToSequence, metas, xforms, xformSys, containerSys, lookupSys);
+            ProcessPvsDeparture(curState.ToSequence, metas, xforms, xformSys, containerSys, lookupSys);
 
             // Check next state (AFTER having created new entities introduced in curstate)
             if (nextState != null)
             {
                 foreach (var es in nextState.EntityStates.Span)
                 {
-                    if (!_entityManager.TryGetEntityData(es.NetEntity, out var uid, out var meta))
+                    if (!_entities.TryGetEntityData(es.NetEntity, out var uid, out var meta))
                         continue;
 
                     // Does the next state actually have any future information about this entity that could be used for interpolation?
@@ -854,15 +854,14 @@ namespace Robust.Client.GameStates
 
                     ref var state = ref CollectionsMarshal.GetValueRefOrAddDefault(_toApply, uid.Value, out var exists);
 
-                    if (exists)
-                        state = (es.NetEntity, meta, state.EnteringPvs, state.LastApplied, state.curState, es);
-                    else
-                        state = (es.NetEntity, meta, false, GameTick.Zero, null, es);
+                    state = exists
+                        ? state with {NextState = es}
+                        : new(uid.Value, es.NetEntity, meta, false, false, GameTick.Zero, null, es, null);
                 }
             }
 
             // Check pending states and see if we need to force any entities to re-run component states.
-            foreach (var uid in _pendingReapplyNetStates.Keys)
+            foreach (var (uid, pending) in _pendingReapplyNetStates)
             {
                 // Original entity referencing the NetEntity may have been deleted.
                 if (!metas.TryGetComponent(uid, out var meta))
@@ -879,51 +878,30 @@ namespace Robust.Client.GameStates
 
                 DebugTools.Assert(!curState.EntityDeletions.Value.Contains(meta.NetEntity));
 
-                // State already being re-applied so don't bulldoze it.
                 ref var state = ref CollectionsMarshal.GetValueRefOrAddDefault(_toApply, uid, out var exists);
 
-                if (exists)
-                    continue;
-
-                state = (meta.NetEntity, meta, false, GameTick.Zero, null, null);
+                state = exists
+                    ? state with {PendingReapply = pending}
+                    : new(uid, meta.NetEntity, meta, false, false, GameTick.Zero, null, null, pending);
             }
 
             _queuedBroadphaseUpdates.Clear();
 
+            using (_prof.Group("Sort States"))
+            {
+                SortStates(_toApply);
+            }
+
             // Apply entity states.
             using (_prof.Group("Apply States"))
             {
-                foreach (var (entity, data) in _toApply)
+                var span = _toApplySorted.AsSpan(0, _toApply.Count);
+                foreach (ref var data in span)
                 {
-#if EXCEPTION_TOLERANCE
-                    try
-                    {
-#endif
-                    HandleEntityState(entity, data.NetEntity, data.Meta, _entities.EventBus, data.curState,
-                            data.nextState, data.LastApplied, curState.ToSequence, data.EnteringPvs);
-#if EXCEPTION_TOLERANCE
-                    }
-                    catch (Exception e)
-                    {
-                        _sawmill.Error($"Caught exception while applying entity state. Entity: {_entities.ToPrettyString(entity)}. Exception: {e}");
-                        _entityManager.DeleteEntity(entity);
-                        RequestFullState();
-                        continue;
-                    }
-#endif
-                    if (!data.EnteringPvs)
-                        continue;
-
-                    // Now that things like collision data, fixtures, and positions have been updated, we queue a
-                    // broadphase update. However, if this entity is parented to some other entity also re-entering PVS,
-                    // we only need to update it's parent (as it recursively updates children anyways).
-                    var xform = xforms.GetComponent(entity);
-                    DebugTools.Assert(xform.Broadphase == BroadphaseData.Invalid);
-                    xform.Broadphase = null;
-                    if (!_toApply.TryGetValue(xform.ParentUid, out var parent) || !parent.EnteringPvs)
-                        _queuedBroadphaseUpdates.Add((entity, xform));
+                    ApplyEntState(data, curState.ToSequence);
                 }
 
+                Array.Clear(_toApplySorted, 0, _toApply.Count);
                 _prof.WriteValue("Count", ProfData.Int32(_toApply.Count));
             }
 
@@ -958,14 +936,166 @@ namespace Robust.Client.GameStates
                 }
             }
 
-            // Initialize and start the newly created entities.
-            if (_toCreate.Count > 0)
-                InitializeAndStart(_toCreate, metas, xforms);
+            // Delete any entities that failed to properly initialize/start
+            foreach (var entity in _brokenEnts)
+            {
+                _entities.DeleteEntity(entity);
+            }
+
+            _brokenEnts.Clear();
 
             _prof.WriteValue("State Size", ProfData.Int32(curSpan.Length));
             _prof.WriteValue("Entered PVS", ProfData.Int32(enteringPvs));
+        }
 
-            return (_toCreate.Keys, detached);
+        private void ApplyEntState(in StateData data, GameTick toTick)
+        {
+            try
+            {
+                HandleEntityState(data, _entities.EventBus, toTick);
+            }
+            catch (Exception e)
+            {
+                _sawmill.Error($"Caught exception while applying entity state. Entity: {_entities.ToPrettyString(data.Uid)}. Exception: {e}");
+                _brokenEnts.Add(data.Uid);
+                RequestFullState();
+#if !EXCEPTION_TOLERANCE
+                throw;
+#endif
+                return;
+            }
+
+            if (data.Created)
+            {
+                try
+                {
+                    _entities.InitializeEntity(data.Uid, data.Meta);
+                    _entities.StartEntity(data.Uid);
+                }
+                catch (Exception e)
+                {
+                    _sawmill.Error(
+                        $"Caught exception while initializing or starting entity: {_entities.ToPrettyString(data.Uid)}. Exception: {e}");
+                    _brokenEnts.Add(data.Uid);
+                    RequestFullState();
+#if !EXCEPTION_TOLERANCE
+                    throw;
+#endif
+                    return;
+                }
+            }
+
+            if (!data.EnteringPvs)
+                return;
+
+            // Now that things like collision data, fixtures, and positions have been updated, we queue a
+            // broadphase update. However, if this entity is parented to some other entity also re-entering PVS,
+            // we only need to update it's parent (as it recursively updates children anyways).
+            var xform = _entities.TransformQuery.Comp(data.Uid);
+            DebugTools.Assert(xform.Broadphase == BroadphaseData.Invalid);
+            xform.Broadphase = null;
+            if (!_toApply.TryGetValue(xform.ParentUid, out var parent) || !parent.EnteringPvs)
+                _queuedBroadphaseUpdates.Add((data.Uid, xform));
+        }
+
+        private void CreateNewEntity(EntityState state, GameTick toTick)
+        {
+            // TODO GAME STATE
+            // store MetaData & Transform information separately.
+            var metaState =
+                (MetaDataComponentState?) state.ComponentChanges.Value?.FirstOrDefault(c => c.NetID == _metaCompNetId)
+                    .State;
+
+            if (metaState == null)
+                throw new MissingMetadataException(state.NetEntity);
+
+            var uid = _entities.CreateEntity(metaState.PrototypeId, out var newMeta);
+            _toApply.Add(uid, new(uid, state.NetEntity, newMeta, true, false, GameTick.Zero, state, null, null));
+            _created.Add(state.NetEntity);
+
+            // Client creates a client-side net entity for the newly created entity.
+            // We need to clear this mapping before assigning the real net id.
+            // TODO NetEntity Jank: prevent the client from creating this in the first place.
+            _entities.ClearNetEntity(newMeta.NetEntity);
+
+            _entities.SetNetEntity(uid, state.NetEntity, newMeta);
+            newMeta.LastStateApplied = toTick;
+
+            // Check if there's any component states awaiting this entity.
+            if (!_entities.PendingNetEntityStates.Remove(state.NetEntity, out var value))
+                return;
+
+            foreach (var (type, owner) in value)
+            {
+                var pending = _pendingReapplyNetStates.GetOrNew(owner);
+                pending.Add(type);
+            }
+        }
+
+        /// <summary>
+        /// Sort states to ensure that we always apply states, initialize, and start parent entities before any of their
+        /// children.
+        /// </summary>
+        private void SortStates(Dictionary<EntityUid, StateData> toApply)
+        {
+            // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
+            if (_toApplySorted == null || _toApplySorted.Length < toApply.Count)
+                Array.Resize(ref _toApplySorted, toApply.Count);
+
+            _sorted.Clear();
+
+            var i = 0;
+            foreach (var (ent, data) in toApply)
+            {
+                AddToSorted(ent, data, ref i);
+            }
+
+            DebugTools.AssertEqual(i, toApply.Count);
+        }
+
+        private void AddToSorted(EntityUid ent, in StateData data, ref int i)
+        {
+            if (!_sorted.Add(ent))
+                return;
+
+            EnsureParentsSorted(ent, data, ref i);
+            _toApplySorted[i++] = data;
+        }
+
+        private void EnsureParentsSorted(EntityUid ent, in StateData data, ref int i)
+        {
+            var parent = GetStateParent(ent, data);
+
+            while (parent != EntityUid.Invalid)
+            {
+                if (_toApply.TryGetValue(parent, out var parentData))
+                {
+                    AddToSorted(parent, parentData, ref i);
+                    // The above method will handle the rest of the transform hierarchy, so we can just return early.
+                    return;
+                }
+
+                parent = _entities.TransformQuery.GetComponent(parent).ParentUid;
+            }
+        }
+
+        /// <summary>
+        /// Get the entity's parent in the game state that is being applies. I.e., if the state contains a new
+        /// transform state, get the parent from that. Otherwise, return the entity's current parent.
+        /// </summary>
+        private EntityUid GetStateParent(EntityUid uid, in StateData data)
+        {
+            // TODO GAME STATE
+            // store MetaData & Transform information separately.
+            if (data.CurState != null
+                && data.CurState.ComponentChanges.Value
+                    .TryFirstOrNull(c => c.NetID == _xformCompNetId, out var found))
+            {
+                var state = (TransformComponentState) found.Value.State!;
+                return _entities.GetEntity(state.ParentID);
+            }
+
+            return _entities.TransformQuery.GetComponent(uid).ParentUid;
         }
 
         /// <inheritdoc />
@@ -1000,7 +1130,7 @@ namespace Robust.Client.GameStates
             _toDelete.Clear();
 
             // Client side entities won't need the transform, but that should always be a tiny minority of entities
-            var metaQuery = _entityManager.AllEntityQueryEnumerator<MetaDataComponent, TransformComponent>();
+            var metaQuery = _entities.AllEntityQueryEnumerator<MetaDataComponent, TransformComponent>();
 
             while (metaQuery.MoveNext(out var ent, out var metadata, out var xform))
             {
@@ -1067,9 +1197,9 @@ namespace Robust.Client.GameStates
             foreach (var netEntity in delSpan)
             {
                 // Don't worry about this for later.
-                _entityManager.PendingNetEntityStates.Remove(netEntity);
+                _entities.PendingNetEntityStates.Remove(netEntity);
 
-                if (!_entityManager.TryGetEntity(netEntity, out var id))
+                if (!_entities.TryGetEntity(netEntity, out var id))
                     continue;
 
                 if (!xforms.TryGetComponent(id, out var xform))
@@ -1099,9 +1229,10 @@ namespace Robust.Client.GameStates
             var containerSys = _entitySystemManager.GetEntitySystem<ContainerSystem>();
             var lookupSys = _entitySystemManager.GetEntitySystem<EntityLookupSystem>();
             Detach(GameTick.MaxValue, null, entities, metas, xforms, xformSys, containerSys, lookupSys);
+            _detached.Clear();
         }
 
-        private List<NetEntity> ProcessPvsDeparture(
+        private void ProcessPvsDeparture(
             GameTick toTick,
             EntityQuery<MetaDataComponent> metas,
             EntityQuery<TransformComponent> xforms,
@@ -1110,25 +1241,23 @@ namespace Robust.Client.GameStates
             EntityLookupSystem lookupSys)
         {
             var toDetach = _processor.GetEntitiesToDetach(toTick, _pvsDetachBudget);
-            var detached = new List<NetEntity>();
 
             if (toDetach.Count == 0)
-                return detached;
+                return;
 
             // TODO optimize
             // If an entity is leaving PVS, so are all of its children. If we can preserve the hierarchy we can avoid
             // things like container insertion and ejection.
 
             using var _ = _prof.Group("Leave PVS");
-            detached.EnsureCapacity(toDetach.Count);
 
+            _detached.Clear();
             foreach (var (tick, ents) in toDetach)
             {
-                Detach(tick, toTick, ents, metas, xforms, xformSys, containerSys, lookupSys, detached);
+                Detach(tick, toTick, ents, metas, xforms, xformSys, containerSys, lookupSys);
             }
 
-            _prof.WriteValue("Count", ProfData.Int32(detached.Count));
-            return detached;
+            _prof.WriteValue("Count", ProfData.Int32(_detached.Count));
         }
 
         private void Detach(GameTick maxTick,
@@ -1138,12 +1267,11 @@ namespace Robust.Client.GameStates
             EntityQuery<TransformComponent> xforms,
             SharedTransformSystem xformSys,
             ContainerSystem containerSys,
-            EntityLookupSystem lookupSys,
-            List<NetEntity>? detached = null)
+            EntityLookupSystem lookupSys)
         {
             foreach (var netEntity in entities)
             {
-                if (!_entityManager.TryGetEntityData(netEntity, out var ent, out var meta))
+                if (!_entities.TryGetEntityData(netEntity, out var ent, out var meta))
                     continue;
 
                 if (meta.LastStateApplied > maxTick)
@@ -1184,159 +1312,75 @@ namespace Robust.Client.GameStates
                         containerSys.AddExpectedEntity(netEntity, container);
                 }
 
-                detached?.Add(netEntity);
+                _detached.Add(netEntity);
             }
         }
 
-        private void InitializeAndStart(
-            Dictionary<NetEntity, EntityState> toCreate,
-            EntityQuery<MetaDataComponent> metas,
-            EntityQuery<TransformComponent> xforms)
-        {
-            _toStart.Clear();
-
-            using (_prof.Group("Initialize Entity"))
-            {
-                EntityUid entity = default;
-                foreach (var netEntity in toCreate.Keys)
-                {
-                    (entity, var meta) = _entityManager.GetEntityData(netEntity);
-                    InitializeRecursive(entity, meta, metas, xforms);
-                }
-            }
-
-            using (_prof.Group("Start Entity"))
-            {
-                foreach (var (entity, netEntity) in _toStart)
-                {
-                    try
-                    {
-                        _entities.StartEntity(entity);
-                    }
-                    catch (Exception e)
-                    {
-                        _sawmill.Error($"Server entity threw in Start:  nent={netEntity}, ent={_entityManager.ToPrettyString(entity)}");
-                        _runtimeLog.LogException(e, $"{nameof(ClientGameStateManager)}.{nameof(InitializeAndStart)}");
-                        _toCreate.Remove(netEntity);
-                        _brokenEnts.Add(entity);
-#if !EXCEPTION_TOLERANCE
-                        throw;
-#endif
-                    }
-                }
-            }
-
-            foreach (var entity in _brokenEnts)
-            {
-                _entityManager.DeleteEntity(entity);
-            }
-            _brokenEnts.Clear();
-        }
-
-        private void InitializeRecursive(
-            EntityUid entity,
-            MetaDataComponent meta,
-            EntityQuery<MetaDataComponent> metas,
-            EntityQuery<TransformComponent> xforms)
-        {
-            var xform = xforms.GetComponent(entity);
-            if (xform.ParentUid is {Valid: true} parent)
-            {
-                var parentMeta = metas.GetComponent(parent);
-                if (parentMeta.EntityLifeStage < EntityLifeStage.Initialized)
-                    InitializeRecursive(parent, parentMeta, metas, xforms);
-            }
-
-            if (meta.EntityLifeStage >= EntityLifeStage.Initialized)
-            {
-                // Was probably already initialized because one of its children appeared earlier in the list.
-                DebugTools.AssertEqual(_toStart.Count(x => x.Item1 == entity), 1);
-                return;
-            }
-
-            try
-            {
-                _entities.InitializeEntity(entity, meta);
-                _toStart.Add((entity, meta.NetEntity));
-            }
-            catch (Exception e)
-            {
-                _sawmill.Error($"Server entity threw in Init: nent={meta.NetEntity}, ent={_entities.ToPrettyString(entity)}");
-                _runtimeLog.LogException(e, $"{nameof(ClientGameStateManager)}.{nameof(InitializeAndStart)}");
-                _toCreate.Remove(meta.NetEntity);
-                _brokenEnts.Add(entity);
-#if !EXCEPTION_TOLERANCE
-                throw;
-#endif
-            }
-        }
-
-        private void HandleEntityState(EntityUid uid, NetEntity netEntity, MetaDataComponent meta, IEventBus bus, EntityState? curState,
-            EntityState? nextState, GameTick lastApplied, GameTick toTick, bool enteringPvs)
+        private void HandleEntityState(in StateData data, IEventBus bus, GameTick toTick)
         {
             _compStateWork.Clear();
 
             // First remove any deleted components
-            if (curState?.NetComponents != null)
+            if (data.CurState?.NetComponents is {} netComps)
             {
                 _toRemove.Clear();
 
-                foreach (var (id, comp) in meta.NetComponents)
+                foreach (var (id, comp) in data.Meta.NetComponents)
                 {
                     DebugTools.Assert(comp.NetSyncEnabled);
 
-                    if (!curState.NetComponents.Contains(id))
+                    if (!netComps.Contains(id))
                         _toRemove.Add(comp);
                 }
 
                 foreach (var comp in _toRemove)
                 {
-                    _entities.RemoveComponent(uid, comp, meta);
+                    _entities.RemoveComponent(data.Uid, comp, data.Meta);
                 }
             }
 
-            if (enteringPvs)
+            if (data.EnteringPvs)
             {
                 // last-server state has already been updated with new information from curState
                 // --> simply reset to the most recent server state.
                 //
                 // as to why we need to reset: because in the process of detaching to null-space, we will have dirtied
                 // the entity. most notably, all entities will have been ejected from their containers.
-                foreach (var (id, state) in _processor.GetLastServerStates(netEntity))
+                foreach (var (id, state) in _processor.GetLastServerStates(data.NetEntity))
                 {
-                    if (!meta.NetComponents.TryGetValue(id, out var comp))
+                    if (!data.Meta.NetComponents.TryGetValue(id, out var comp))
                     {
                         comp = _compFactory.GetComponent(id);
-                        _entityManager.AddComponent(uid, comp, true, metadata: meta);
+                        _entities.AddComponent(data.Uid, comp, true, metadata: data.Meta);
                     }
 
                     _compStateWork[id] = (comp, state, null);
                 }
             }
-            else if (curState != null)
+            else if (data.CurState != null)
             {
-                foreach (var compChange in curState.ComponentChanges.Span)
+                foreach (var compChange in data.CurState.ComponentChanges.Span)
                 {
-                    if (!meta.NetComponents.TryGetValue(compChange.NetID, out var comp))
+                    if (!data.Meta.NetComponents.TryGetValue(compChange.NetID, out var comp))
                     {
                         comp = _compFactory.GetComponent(compChange.NetID);
-                        _entityManager.AddComponent(uid, comp, true, metadata:meta);
+                        _entities.AddComponent(data.Uid, comp, true, metadata: data.Meta);
                     }
-                    else if (compChange.LastModifiedTick <= lastApplied && lastApplied != GameTick.Zero)
+                    else if (compChange.LastModifiedTick <= data.LastApplied && data.LastApplied != GameTick.Zero)
                         continue;
 
                     _compStateWork[compChange.NetID] = (comp, compChange.State, null);
                 }
             }
 
-            if (nextState != null)
+            if (data.NextState != null)
             {
-                foreach (var compState in nextState.ComponentChanges.Span)
+                foreach (var compState in data.NextState.ComponentChanges.Span)
                 {
                     if (compState.LastModifiedTick != toTick + 1)
                         continue;
 
-                    if (!meta.NetComponents.TryGetValue(compState.NetID, out var comp))
+                    if (!data.Meta.NetComponents.TryGetValue(compState.NetID, out var comp))
                     {
                         // The component can be null here due to interp, because the NEXT state will have a new
                         // component, but the component does not yet exist.
@@ -1354,9 +1398,10 @@ namespace Robust.Client.GameStates
             }
 
             // If we have a NetEntity we reference come in then apply their state.
-            if (_pendingReapplyNetStates.TryGetValue(uid, out var reapplyTypes))
+            DebugTools.Assert(_pendingReapplyNetStates.ContainsKey(data.Uid) == (data.PendingReapply != null));
+            if (data.PendingReapply is {} reapplyTypes)
             {
-                var lastState = _processor.GetLastServerStates(netEntity);
+                var lastState = _processor.GetLastServerStates(data.NetEntity);
 
                 foreach (var type in reapplyTypes)
                 {
@@ -1366,7 +1411,7 @@ namespace Robust.Client.GameStates
                     if (netId == null)
                         continue;
 
-                    if (!meta.NetComponents.TryGetValue(netId.Value, out var comp) ||
+                    if (!data.Meta.NetComponents.TryGetValue(netId.Value, out var comp) ||
                         !lastState.TryGetValue(netId.Value, out var lastCompState))
                     {
                         continue;
@@ -1388,7 +1433,7 @@ namespace Robust.Client.GameStates
                     continue;
 
                 var handleState = new ComponentHandleState(cur, next);
-                bus.RaiseComponentEvent(uid, comp, ref handleState);
+                bus.RaiseComponentEvent(data.Uid, comp, ref handleState);
             }
         }
 
@@ -1510,7 +1555,7 @@ namespace Robust.Client.GameStates
         {
             using var _ = _timing.StartStateApplicationArea();
 
-            var query = _entityManager.AllEntityQueryEnumerator<MetaDataComponent>();
+            var query = _entities.AllEntityQueryEnumerator<MetaDataComponent>();
 
             while (query.MoveNext(out var uid, out var meta))
             {
@@ -1536,14 +1581,14 @@ namespace Robust.Client.GameStates
                 if (!meta.NetComponents.TryGetValue(id, out var comp))
                 {
                     comp = _compFactory.GetComponent(id);
-                    _entityManager.AddComponent(uid, comp, true, meta);
+                    _entities.AddComponent(uid, comp, true, meta);
                 }
 
                 if (state == null)
                     continue;
 
                 var handleState = new ComponentHandleState(state, null);
-                _entityManager.EventBus.RaiseComponentEvent(uid, comp, ref handleState);
+                _entities.EventBus.RaiseComponentEvent(uid, comp, ref handleState);
             }
 
             // ensure we don't have any extra components

Robust.Client/GameStates/IClientGameStateManager.cs

@@ -82,11 +82,7 @@ namespace Robust.Client.GameStates
         /// </summary>
         IEnumerable<NetEntity> ApplyGameState(GameState curState, GameState? nextState);
 
-        /// <summary>
-        ///     Generates implicit component states for newly created entities.
-        ///     This should always be called after running <see cref="ApplyGameState(GameState, GameState)"/>.
-        /// </summary>
-        void GenerateImplicitStates(IEnumerable<NetEntity> states);
+        void MergeImplicitData();
 
         /// <summary>
         ///     Resets any entities that have changed while predicting future ticks.

Robust.Client/GameStates/PvsOverrideSystem.cs

@@ -0,0 +1,5 @@
+using Robust.Shared.GameStates;
+
+namespace Robust.Client.GameStates;
+
+public sealed partial class PvsOverrideSystem : SharedPvsOverrideSystem;

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

@@ -125,7 +125,8 @@ namespace Robust.Client.Graphics.Clyde
         {
             DebugTools.Assert(space != OverlaySpace.ScreenSpaceBelowWorld && space != OverlaySpace.ScreenSpace);
 
-            var args = new OverlayDrawArgs(space, null, vp, _renderHandle.DrawingHandleWorld, new UIBox2i((0, 0), vp.Size), vp.Eye!.Position.MapId, worldBox, worldBounds);
+            var mapId = vp.Eye!.Position.MapId;
+            var args = new OverlayDrawArgs(space, null, vp, _renderHandle, new UIBox2i((0, 0), vp.Size), _mapManager.GetMapEntityIdOrThrow(mapId), mapId, worldBox, worldBounds);
 
             if (!overlay.BeforeDraw(args))
                 return;
@@ -165,7 +166,7 @@ namespace Robust.Client.Graphics.Clyde
         private void RenderOverlaysDirect(
             Viewport vp,
             IViewportControl vpControl,
-            DrawingHandleBase handle,
+            IRenderHandle handle,
             OverlaySpace space,
             in UIBox2i bounds)
         {
@@ -175,8 +176,9 @@ namespace Robust.Client.Graphics.Clyde
 
             var worldBounds = CalcWorldBounds(vp);
             var worldAABB = worldBounds.CalcBoundingBox();
+            var mapId = vp.Eye!.Position.MapId;
 
-            var args = new OverlayDrawArgs(space, vpControl, vp, handle, bounds, vp.Eye!.Position.MapId, worldAABB, worldBounds);
+            var args = new OverlayDrawArgs(space, vpControl, vp, handle, bounds, _mapManager.GetMapEntityIdOrThrow(mapId), mapId, worldAABB, worldBounds);
 
             foreach (var overlay in list)
             {
@@ -421,12 +423,19 @@ namespace Robust.Client.Graphics.Clyde
 
             var oldTransform = _currentMatrixModel;
             var oldScissor = _currentScissorState;
+            var oldMatrixProj = _currentMatrixProj;
+            var oldMatrixView = _currentMatrixView;
+            var oldBoundTarget = _currentBoundRenderTarget;
+            var oldRenderTarget = _currentRenderTarget;
+            var oldShader = _queuedShaderInstance;
+            var oldCaps = _glCaps;
+
+            // Need to get state before flushing render queue in case they modify the original state.
+            var state = PushRenderStateFull();
 
             // Have to flush the render queue so that all commands finish rendering to the previous framebuffer.
             FlushRenderQueue();
 
-            var state = PushRenderStateFull();
-
             {
                 BindRenderTargetFull(RtToLoaded(rt));
                 if (clearColor is not null)
@@ -448,8 +457,16 @@ namespace Robust.Client.Graphics.Clyde
             PopRenderStateFull(state);
             _updateUniformConstants(_currentRenderTarget.Size);
 
-            SetScissorFull(oldScissor);
             _currentMatrixModel = oldTransform;
+
+            DebugTools.Assert(oldCaps.Equals(_glCaps));
+            DebugTools.Assert(_currentMatrixModel.Equals(oldTransform));
+            DebugTools.Assert(_currentScissorState.Equals(oldScissor));
+            DebugTools.Assert(_currentMatrixProj.Equals(oldMatrixProj));
+            DebugTools.Assert(oldMatrixView.Equals(_currentMatrixView));
+            DebugTools.Assert(oldRenderTarget.Equals(_currentRenderTarget));
+            DebugTools.Assert(oldBoundTarget.Equals(_currentBoundRenderTarget));
+            DebugTools.Assert(oldShader.Equals(_queuedShaderInstance));
         }
 
         private void RenderViewport(Viewport viewport)

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

@@ -1,21 +1,19 @@
 using System;
 using System.Collections.Generic;
 using System.Buffers;
+using System.Diagnostics.Contracts;
 using System.Numerics;
 using OpenToolkit.Graphics.OpenGL4;
 using Robust.Client.GameObjects;
 using Robust.Client.ResourceManagement;
 using Robust.Shared;
 using Robust.Shared.GameObjects;
-using Robust.Shared.IoC;
-using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Map.Components;
 using Robust.Shared.Maths;
-using OGLTextureWrapMode = OpenToolkit.Graphics.OpenGL.TextureWrapMode;
 using TKStencilOp = OpenToolkit.Graphics.OpenGL4.StencilOp;
 using Robust.Shared.Physics;
-using Robust.Client.ComponentTrees;
+using Robust.Shared.Enums;
 using Robust.Shared.Graphics;
 using static Robust.Shared.GameObjects.OccluderComponent;
 using Robust.Shared.Utility;
@@ -279,8 +277,7 @@ namespace Robust.Client.Graphics.Clyde
         {
             const float arbitraryDistanceMax = 1234;
 
-            GL.Disable(EnableCap.Blend);
-            CheckGlError();
+            IsBlending = false;
 
             GL.Enable(EnableCap.DepthTest);
             CheckGlError();
@@ -329,8 +326,7 @@ namespace Robust.Client.Graphics.Clyde
             GL.Disable(EnableCap.DepthTest);
             CheckGlError();
 
-            GL.Enable(EnableCap.Blend);
-            CheckGlError();
+            IsBlending = true;
         }
 
         private void DrawLightsAndFov(Viewport viewport, Box2Rotated worldBounds, Box2 worldAABB, IEye eye)
@@ -394,21 +390,43 @@ namespace Robust.Client.Graphics.Clyde
                 FinalizeDepthDraw();
             }
 
-            GL.Enable(EnableCap.StencilTest);
-            _isStencilling = true;
+            IsStencilling = true;
 
             var (lightW, lightH) = GetLightMapSize(viewport.Size);
             GL.Viewport(0, 0, lightW, lightH);
             CheckGlError();
 
             BindRenderTargetImmediate(RtToLoaded(viewport.LightRenderTarget));
+            DebugTools.Assert(_currentBoundRenderTarget.TextureHandle.Equals(viewport.LightRenderTarget.Texture.TextureId));
             CheckGlError();
-            GLClearColor(_entityManager.GetComponentOrNull<MapLightComponent>(mapUid)?.AmbientLightColor ?? MapLightComponent.DefaultColor);
+
+            var clearEv = new GetClearColorEvent();
+            _entityManager.EventBus.RaiseEvent(EventSource.Local, ref clearEv);
+
+            var clearColor = clearEv.Color ?? GetClearColor(mapUid);
+            GLClearColor(clearColor);
             GL.ClearStencil(0xFF);
             GL.StencilMask(0xFF);
             GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.StencilBufferBit);
             CheckGlError();
 
+            var oldTarget = _currentRenderTarget;
+            var oldProj = _currentMatrixProj;
+            var oldShader = _queuedShaderInstance;
+            var oldModel = _currentMatrixModel;
+            var oldScissor = _currentScissorState;
+            var state = PushRenderStateFull();
+
+            RenderOverlays(viewport, OverlaySpace.BeforeLighting, worldAABB, worldBounds);
+            PopRenderStateFull(state);
+
+            DebugTools.Assert(oldScissor.Equals(_currentScissorState));
+            DebugTools.Assert(oldModel.Equals(_currentMatrixModel));
+            DebugTools.Assert(oldShader.Equals(_queuedShaderInstance));
+            DebugTools.Assert(oldProj.Equals(_currentMatrixProj));
+            DebugTools.Assert(oldTarget.Equals(_currentRenderTarget));
+            DebugTools.Assert(_currentBoundRenderTarget.TextureHandle.Equals(viewport.LightRenderTarget.Texture.TextureId));
+
             ApplyLightingFovToBuffer(viewport, eye);
 
             var lightShader = _loadedShaders[_enableSoftShadows ? _lightSoftShaderHandle : _lightHardShaderHandle]
@@ -509,13 +527,12 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             ResetBlendFunc();
-            GL.Disable(EnableCap.StencilTest);
-            _isStencilling = false;
+            IsStencilling = false;
 
             CheckGlError();
 
             if (_cfg.GetCVar(CVars.LightBlur))
-                BlurLights(viewport, eye);
+                BlurRenderTarget(viewport, viewport.LightRenderTarget, viewport.LightBlurTarget, eye, 14f);
 
             using (_prof.Group("BlurOntoWalls"))
             {
@@ -531,9 +548,8 @@ namespace Robust.Client.Graphics.Clyde
             GL.Viewport(0, 0, viewport.Size.X, viewport.Size.Y);
             CheckGlError();
 
-            Array.Clear(_lightsToRenderList, 0, count);
-
             _lightingReady = true;
+            Array.Clear(_lightsToRenderList, 0, count);
         }
 
         private static bool LightQuery(ref (
@@ -643,21 +659,33 @@ namespace Robust.Client.Graphics.Clyde
             return (state.count, expandedBounds);
         }
 
-        private void BlurLights(Viewport viewport, IEye eye)
+        /// <inheritdoc/>
+        [Pure]
+        public Color GetClearColor(EntityUid mapUid)
         {
-            using var _ = DebugGroup(nameof(BlurLights));
+            return _entityManager.GetComponentOrNull<MapLightComponent>(mapUid)?.AmbientLightColor ??
+                MapLightComponent.DefaultColor;
+        }
 
-            GL.Disable(EnableCap.Blend);
-            CheckGlError();
+        /// <inheritdoc/>
+        public void BlurRenderTarget(IClydeViewport viewport, IRenderTarget target, IRenderTarget blurBuffer, IEye eye, float multiplier)
+        {
+            if (target is not RenderTexture rTexture || blurBuffer is not RenderTexture blurTexture)
+                return;
+
+            using var _ = DebugGroup(nameof(BlurRenderTarget));
+
+            var state = PushRenderStateFull();
+            IsBlending = false;
             CalcScreenMatrices(viewport.Size, out var proj, out var view);
             SetProjViewBuffer(proj, view);
 
             var shader = _loadedShaders[_lightBlurShaderHandle].Program;
             shader.Use();
 
-            SetupGlobalUniformsImmediate(shader, viewport.LightRenderTarget.Texture);
+            SetupGlobalUniformsImmediate(shader, rTexture.Texture);
 
-            var size = viewport.LightRenderTarget.Size;
+            var size = target.Size;
             shader.SetUniformMaybe("size", (Vector2)size);
             shader.SetUniformTextureMaybe(UniIMainTexture, TextureUnit.Texture0);
 
@@ -667,14 +695,13 @@ namespace Robust.Client.Graphics.Clyde
             // Initially we're pulling from the light render target.
             // So we set it out of the loop so
             // _wallBleedIntermediateRenderTarget2 gets bound at the end of the loop body.
-            SetTexture(TextureUnit.Texture0, viewport.LightRenderTarget.Texture);
+            SetTexture(TextureUnit.Texture0, rTexture.Texture);
 
             // Have to scale the blurring radius based on viewport size and camera zoom.
-            const float refCameraHeight = 14;
             var facBase = _cfg.GetCVar(CVars.LightBlurFactor);
             var cameraSize = eye.Zoom.Y * viewport.Size.Y * (1 / viewport.RenderScale.Y) / EyeManager.PixelsPerMeter;
             // 7e-3f is just a magic factor that makes it look ok.
-            var factor = facBase * (refCameraHeight / cameraSize);
+            var factor = facBase * (multiplier / cameraSize);
 
             // Multi-iteration gaussian blur.
             for (var i = 3; i > 0; i--)
@@ -683,35 +710,31 @@ namespace Robust.Client.Graphics.Clyde
                 // Set factor.
                 shader.SetUniformMaybe("radius", scale);
 
-                BindRenderTargetFull(viewport.LightBlurTarget);
+                BindRenderTargetImmediate(RtToLoaded(blurBuffer));
 
                 // Blur horizontally to _wallBleedIntermediateRenderTarget1.
                 shader.SetUniformMaybe("direction", Vector2.UnitX);
                 _drawQuad(Vector2.Zero, viewport.Size, Matrix3x2.Identity, shader);
 
-                SetTexture(TextureUnit.Texture0, viewport.LightBlurTarget.Texture);
+                SetTexture(TextureUnit.Texture0, blurTexture.Texture);
 
-                BindRenderTargetFull(viewport.LightRenderTarget);
+                BindRenderTargetImmediate(RtToLoaded(rTexture));
 
                 // Blur vertically to _wallBleedIntermediateRenderTarget2.
                 shader.SetUniformMaybe("direction", Vector2.UnitY);
                 _drawQuad(Vector2.Zero, viewport.Size, Matrix3x2.Identity, shader);
 
-                SetTexture(TextureUnit.Texture0, viewport.LightRenderTarget.Texture);
+                SetTexture(TextureUnit.Texture0, rTexture.Texture);
             }
 
-            GL.Enable(EnableCap.Blend);
-            CheckGlError();
-            // We didn't trample over the old _currentMatrices so just roll it back.
-            SetProjViewBuffer(_currentMatrixProj, _currentMatrixView);
+            PopRenderStateFull(state);
         }
 
         private void BlurOntoWalls(Viewport viewport, IEye eye)
         {
             using var _ = DebugGroup(nameof(BlurOntoWalls));
 
-            GL.Disable(EnableCap.Blend);
-            CheckGlError();
+            IsBlending = false;
             CalcScreenMatrices(viewport.Size, out var proj, out var view);
             SetProjViewBuffer(proj, view);
 
@@ -761,8 +784,7 @@ namespace Robust.Client.Graphics.Clyde
                 SetTexture(TextureUnit.Texture0, viewport.WallBleedIntermediateRenderTarget2.Texture);
             }
 
-            GL.Enable(EnableCap.Blend);
-            CheckGlError();
+            IsBlending = true;
             // We didn't trample over the old _currentMatrices so just roll it back.
             SetProjViewBuffer(_currentMatrixProj, _currentMatrixView);
         }
@@ -775,8 +797,7 @@ namespace Robust.Client.Graphics.Clyde
 
             GL.Viewport(0, 0, viewport.LightRenderTarget.Size.X, viewport.LightRenderTarget.Size.Y);
             CheckGlError();
-            GL.Disable(EnableCap.Blend);
-            CheckGlError();
+            IsBlending = false;
 
             var shader = _loadedShaders[_mergeWallLayerShaderHandle].Program;
             shader.Use();
@@ -796,8 +817,7 @@ namespace Robust.Client.Graphics.Clyde
                 IntPtr.Zero);
             CheckGlError();
 
-            GL.Enable(EnableCap.Blend);
-            CheckGlError();
+            IsBlending = true;
         }
 
         private void ApplyFovToBuffer(Viewport viewport, IEye eye)
@@ -827,8 +847,7 @@ namespace Robust.Client.Graphics.Clyde
             FovSetTransformAndBlit(viewport, eye.Position.Position, fovShader);
 
             GL.StencilMask(0x00);
-            GL.Disable(EnableCap.StencilTest);
-            _isStencilling = false;
+            IsStencilling = false;
         }
 
         private void ApplyLightingFovToBuffer(Viewport viewport, IEye eye)
@@ -1135,22 +1154,20 @@ 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 };
 
             viewport.LightRenderTarget?.Dispose();
             viewport.WallMaskRenderTarget?.Dispose();
             viewport.WallBleedIntermediateRenderTarget1?.Dispose();
             viewport.WallBleedIntermediateRenderTarget2?.Dispose();
+            var lightMapColorFormat = _hasGLFloatFramebuffers
+                ? RenderTargetColorFormat.R11FG11FB10F
+                : RenderTargetColorFormat.Rgba8;
+            var lightMapSampleParameters = new TextureSampleParameters { Filter = true };
 
             viewport.WallMaskRenderTarget = CreateRenderTarget(viewport.Size, RenderTargetColorFormat.R8,
                 name: $"{viewport.Name}-{nameof(viewport.WallMaskRenderTarget)}");
 
-            viewport.LightRenderTarget = CreateRenderTarget(lightMapSize,
-                new RenderTargetFormatParameters(lightMapColorFormat, hasDepthStencil: true),
-                lightMapSampleParameters,
+            viewport.LightRenderTarget = (RenderTexture) CreateLightRenderTarget(lightMapSize,
                 $"{viewport.Name}-{nameof(viewport.LightRenderTarget)}");
 
             viewport.LightBlurTarget = CreateRenderTarget(lightMapSize,
@@ -1158,11 +1175,13 @@ namespace Robust.Client.Graphics.Clyde
                 lightMapSampleParameters,
                 $"{viewport.Name}-{nameof(viewport.LightBlurTarget)}");
 
-            viewport.WallBleedIntermediateRenderTarget1 = CreateRenderTarget(lightMapSizeQuart, lightMapColorFormat,
+            viewport.WallBleedIntermediateRenderTarget1 = CreateRenderTarget(lightMapSizeQuart,
+                new RenderTargetFormatParameters(lightMapColorFormat),
                 lightMapSampleParameters,
                 $"{viewport.Name}-{nameof(viewport.WallBleedIntermediateRenderTarget1)}");
 
-            viewport.WallBleedIntermediateRenderTarget2 = CreateRenderTarget(lightMapSizeQuart, lightMapColorFormat,
+            viewport.WallBleedIntermediateRenderTarget2 = CreateRenderTarget(lightMapSizeQuart,
+                new RenderTargetFormatParameters(lightMapColorFormat),
                 lightMapSampleParameters,
                 $"{viewport.Name}-{nameof(viewport.WallBleedIntermediateRenderTarget2)}");
         }

Robust.Client/Graphics/Clyde/Clyde.RenderTargets.cs

@@ -30,6 +30,20 @@ namespace Robust.Client.Graphics.Clyde
         // It, like _mainWindowRenderTarget, is initialized in Clyde's constructor
         private LoadedRenderTarget _currentBoundRenderTarget;
 
+
+        public IRenderTexture CreateLightRenderTarget(Vector2i size, string? name = null, bool depthStencil = true)
+        {
+            var lightMapColorFormat = _hasGLFloatFramebuffers
+                ? RTCF.R11FG11FB10F
+                : RTCF.Rgba8;
+            var lightMapSampleParameters = new TextureSampleParameters { Filter = true };
+
+            return CreateRenderTarget(size,
+                new RenderTargetFormatParameters(lightMapColorFormat, hasDepthStencil: depthStencil),
+                lightMapSampleParameters,
+                name: name);
+        }
+
         IRenderTexture IClyde.CreateRenderTarget(Vector2i size, RenderTargetFormatParameters format,
             TextureSampleParameters? sampleParameters, string? name)
         {
@@ -204,7 +218,8 @@ namespace Robust.Client.Graphics.Clyde
                 Size = size,
                 TextureHandle = textureObject.TextureId,
                 MemoryPressure = pressure,
-                ColorFormat = format.ColorFormat
+                ColorFormat = format.ColorFormat,
+                SampleParameters = sampleParameters,
             };
 
             //GC.AddMemoryPressure(pressure);
@@ -251,9 +266,15 @@ namespace Robust.Client.Graphics.Clyde
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private LoadedRenderTarget RtToLoaded(RenderTargetBase rt)
+        private LoadedRenderTarget RtToLoaded(IRenderTarget rt)
         {
-            return _renderTargets[rt.Handle];
+            switch (rt)
+            {
+                case RenderTargetBase based:
+                    return _renderTargets[based.Handle];
+                default:
+                    throw new NotImplementedException();
+            }
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -302,6 +323,8 @@ namespace Robust.Client.Graphics.Clyde
             // Renderbuffer handle
             public GLHandle DepthStencilHandle;
             public long MemoryPressure;
+
+            public TextureSampleParameters? SampleParameters;
         }
 
         private abstract class RenderTargetBase : IRenderTarget

Robust.Client/Graphics/Clyde/Clyde.Rendering.cs

@@ -90,9 +90,61 @@ namespace Robust.Client.Graphics.Clyde
         // (queue) and (misc), current state of the scissor test. Null if disabled.
         private UIBox2i? _currentScissorState;
 
-        // Some simple flags that basically just tracks the current state of glEnable(GL_STENCIL/GL_SCISSOR_TEST)
-        private bool _isScissoring;
-        private bool _isStencilling;
+        /// <summary>
+        /// Tracks enabled GL capabilities for renderer state.
+        /// </summary>
+        private GLCaps _glCaps = GLCaps.None;
+
+        private bool IsStencilling
+        {
+            get => (_glCaps & GLCaps.Stencilling) == GLCaps.Stencilling;
+            set
+            {
+                if (value == IsStencilling)
+                    return;
+
+                if (value)
+                {
+                    _glCaps |= GLCaps.Stencilling;
+                    GL.Enable(EnableCap.StencilTest);
+                }
+                else
+                {
+                    _glCaps &= ~GLCaps.Stencilling;
+                    GL.Disable(EnableCap.StencilTest);
+                }
+
+                CheckGlError();
+            }
+        }
+
+        private bool IsBlending
+        {
+            get => (_glCaps & GLCaps.Blending) == GLCaps.Blending;
+            set
+            {
+                if (value == IsBlending)
+                    return;
+
+                if (value)
+                {
+                    _glCaps |= GLCaps.Blending;
+                    GL.Enable(EnableCap.Blend);
+                }
+                else
+                {
+                    _glCaps &= ~GLCaps.Blending;
+                    GL.Disable(EnableCap.Blend);
+                }
+
+                CheckGlError();
+            }
+        }
+
+        private bool IsScissoring
+        {
+            get => _currentScissorState != null;
+        }
 
         private readonly RefList<RenderCommand> _queuedRenderCommands = new RefList<RenderCommand>();
 
@@ -364,16 +416,17 @@ namespace Robust.Client.Graphics.Clyde
 
         private void SetScissorImmediate(bool enable, in UIBox2i box)
         {
-            var oldIsScissoring = _isScissoring;
-            _isScissoring = enable;
-            if (_isScissoring)
+            if (enable)
             {
-                if (!oldIsScissoring)
-                {
-                    GL.Enable(EnableCap.ScissorTest);
-                    CheckGlError();
-                }
+                GL.Enable(EnableCap.ScissorTest);
+            }
+            else
+            {
+                GL.Disable(EnableCap.ScissorTest);
+            }
 
+            if (enable)
+            {
                 // Don't forget to flip it, these coordinates have bottom left as origin.
                 // TODO: Broken when rendering to non-screen render targets.
 
@@ -387,11 +440,6 @@ namespace Robust.Client.Graphics.Clyde
                 }
                 CheckGlError();
             }
-            else if (oldIsScissoring)
-            {
-                GL.Disable(EnableCap.ScissorTest);
-                CheckGlError();
-            }
         }
 
         // NOTE: sRGB IS IN LINEAR IF FRAMEBUFFER_SRGB IS ACTIVE.
@@ -420,17 +468,11 @@ namespace Robust.Client.Graphics.Clyde
             var program = shader.Program;
 
             program.Use();
+            IsStencilling = instance.Stencil.Enabled;
 
             // Handle stencil parameters.
             if (instance.Stencil.Enabled)
             {
-                if (!_isStencilling)
-                {
-                    GL.Enable(EnableCap.StencilTest);
-                    CheckGlError();
-                    _isStencilling = true;
-                }
-
                 GL.StencilMask(instance.Stencil.WriteMask);
                 CheckGlError();
                 GL.StencilFunc(ToGLStencilFunc(instance.Stencil.Func), instance.Stencil.Ref, instance.Stencil.ReadMask);
@@ -438,12 +480,6 @@ namespace Robust.Client.Graphics.Clyde
                 GL.StencilOp(TKStencilOp.Keep, TKStencilOp.Keep, ToGLStencilOp(instance.Stencil.Op));
                 CheckGlError();
             }
-            else if (_isStencilling)
-            {
-                GL.Disable(EnableCap.StencilTest);
-                CheckGlError();
-                _isStencilling = false;
-            }
 
             if (instance.Parameters.Count == 0)
                 return (program, instance);
@@ -859,17 +895,34 @@ namespace Robust.Client.Graphics.Clyde
 
         private FullStoredRendererState PushRenderStateFull()
         {
-            return new FullStoredRendererState(_currentMatrixProj, _currentMatrixView, _currentRenderTarget);
+            return new FullStoredRendererState(
+                _currentMatrixProj,
+                _currentMatrixView,
+                _currentBoundRenderTarget,
+                _currentRenderTarget,
+                _queuedShaderInstance,
+                _currentScissorState,
+                _glCaps);
         }
 
         private void PopRenderStateFull(in FullStoredRendererState state)
         {
             SetProjViewFull(state.ProjMatrix, state.ViewMatrix);
-            BindRenderTargetFull(state.RenderTarget);
+            BindRenderTargetImmediate(state.BoundRenderTarget);
 
-            var (width, height) = state.RenderTarget.Size;
+            _queuedShaderInstance = state.QueuedShaderInstance;
+            _currentRenderTarget = state.RenderTarget;
+            var (width, height) = state.BoundRenderTarget.Size;
             GL.Viewport(0, 0, width, height);
-            CheckGlError();
+
+            IsStencilling = (state.GLCaps & GLCaps.Stencilling) == GLCaps.Stencilling;
+            IsBlending = (state.GLCaps & GLCaps.Blending) == GLCaps.Blending;
+
+            SetScissorFull(state.ScissorState);
+
+            GL.ClearStencil(0xFF);
+            GL.StencilMask(0xFF);
+            GL.Clear(ClearBufferMask.StencilBufferBit);
         }
 
         private void SetViewportImmediate(Box2i box)
@@ -1061,15 +1114,44 @@ namespace Robust.Client.Graphics.Clyde
         {
             public readonly Matrix3x2 ProjMatrix;
             public readonly Matrix3x2 ViewMatrix;
+            public readonly LoadedRenderTarget BoundRenderTarget;
             public readonly LoadedRenderTarget RenderTarget;
+            public readonly ClydeShaderInstance QueuedShaderInstance;
 
-            public FullStoredRendererState(in Matrix3x2 projMatrix, in Matrix3x2 viewMatrix,
-                LoadedRenderTarget renderTarget)
+            public readonly UIBox2i? ScissorState;
+
+            public readonly GLCaps GLCaps;
+
+            public FullStoredRendererState(
+                in Matrix3x2 projMatrix,
+                in Matrix3x2 viewMatrix,
+                LoadedRenderTarget boundRenderTarget,
+                LoadedRenderTarget renderTarget,
+                ClydeShaderInstance queuedShaderInstance,
+                UIBox2i? scissorState,
+                GLCaps glcaps
+                )
             {
                 ProjMatrix = projMatrix;
                 ViewMatrix = viewMatrix;
+                BoundRenderTarget = boundRenderTarget;
                 RenderTarget = renderTarget;
+                QueuedShaderInstance = queuedShaderInstance;
+
+                ScissorState = scissorState;
+                GLCaps = glcaps;
             }
         }
+
+        [Flags]
+        private enum GLCaps : ushort
+        {
+            // If you add flags here make sure to update PopRenderState!
+            None = 0,
+
+            Blending = 1 << 0,
+
+            Stencilling = 1 << 2,
+        }
     }
 }

Robust.Client/Graphics/Clyde/Clyde.Viewport.cs

@@ -171,7 +171,7 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             public void RenderScreenOverlaysBelow(
-                DrawingHandleScreen handle,
+                IRenderHandle handle,
                 IViewportControl control,
                 in UIBox2i viewportBounds)
             {
@@ -179,7 +179,7 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             public void RenderScreenOverlaysAbove(
-                DrawingHandleScreen handle,
+                IRenderHandle handle,
                 IViewportControl control,
                 in UIBox2i viewportBounds)
             {

Robust.Client/Graphics/Clyde/Clyde.cs

@@ -21,6 +21,7 @@ using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Profiling;
+using Robust.Shared.Prototypes;
 using Robust.Shared.Timing;
 using TextureWrapMode = Robust.Shared.Graphics.TextureWrapMode;
 
@@ -245,7 +246,7 @@ namespace Robust.Client.Graphics.Clyde
                 overrideVersion != null,
                 _windowing!.GetDescription());
 
-            GL.Enable(EnableCap.Blend);
+            IsBlending = true;
             if (_hasGLSrgb && !_isGLES)
             {
                 GL.Enable(EnableCap.FramebufferSrgb);

Robust.Client/Graphics/Clyde/ClydeHeadless.cs

@@ -9,6 +9,7 @@ using Robust.Client.Input;
 using Robust.Client.ResourceManagement;
 using Robust.Client.UserInterface;
 using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.GameObjects;
 using Robust.Shared.Graphics;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
@@ -189,6 +190,22 @@ namespace Robust.Client.Graphics.Clyde
             return new DummyTexture(size);
         }
 
+        /// <inheritdoc />
+        public Color GetClearColor(EntityUid mapUid)
+        {
+            return Color.Transparent;
+        }
+
+        public void BlurRenderTarget(IClydeViewport viewport, IRenderTarget target, IRenderTarget blurBuffer, IEye eye, float multiplier)
+        {
+            // NOOP
+        }
+
+        public IRenderTexture CreateLightRenderTarget(Vector2i size, string? name = null, bool depthStencil = true)
+        {
+            return CreateRenderTarget(size, new RenderTargetFormatParameters(RenderTargetColorFormat.R8, hasDepthStencil: depthStencil), null, name: name);
+        }
+
         public IRenderTexture CreateRenderTarget(Vector2i size, RenderTargetFormatParameters format,
             TextureSampleParameters? sampleParameters = null, string? name = null)
         {
@@ -497,7 +514,7 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             public void RenderScreenOverlaysBelow(
-                DrawingHandleScreen handle,
+                IRenderHandle handle,
                 IViewportControl control,
                 in UIBox2i viewportBounds)
             {
@@ -505,7 +522,7 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             public void RenderScreenOverlaysAbove(
-                DrawingHandleScreen handle,
+                IRenderHandle handle,
                 IViewportControl control,
                 in UIBox2i viewportBounds)
             {

Robust.Client/Graphics/IClyde.cs

@@ -1,12 +1,15 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.Contracts;
 using System.IO;
 using System.Numerics;
 using System.Threading.Tasks;
+using Robust.Shared.GameObjects;
 using Robust.Shared.Graphics;
 using Robust.Shared.Maths;
 using SixLabors.ImageSharp;
 using SixLabors.ImageSharp.PixelFormats;
+using Color = Robust.Shared.Maths.Color;
 
 namespace Robust.Client.Graphics
 {
@@ -71,6 +74,24 @@ namespace Robust.Client.Graphics
             in TextureLoadParameters? loadParams = null)
             where T : unmanaged, IPixel<T>;
 
+        /// <summary>
+        /// Gets the clear color for the specified map viewport.
+        /// </summary>
+        [Pure]
+        Color GetClearColor(EntityUid mapUid);
+
+        /// <summary>
+        /// Applies a blur to the specified render target. Requires a separate buffer with similar properties to draw intermediate steps into.
+        /// </summary>
+        /// <param name="viewport">The viewport being used for drawing.</param>
+        /// <param name="target">The blur target.</param>
+        /// <param name="blurBuffer">The separate buffer to draw into.</param>
+        /// <param name="eye">The eye being drawn with.</param>
+        /// <param name="multiplier">Scale of how much blur to blur by.</param>
+        void BlurRenderTarget(IClydeViewport viewport, IRenderTarget target, IRenderTarget blurBuffer, IEye eye, float multiplier);
+
+        IRenderTexture CreateLightRenderTarget(Vector2i size, string? name = null, bool depthStencil = true);
+
         IRenderTexture CreateRenderTarget(Vector2i size, RenderTargetFormatParameters format,
             TextureSampleParameters? sampleParameters = null, string? name = null);
 

Robust.Client/Graphics/IClydeViewport.cs

@@ -18,6 +18,7 @@ namespace Robust.Client.Graphics
         /// </summary>
         IRenderTexture RenderTarget { get; }
         IRenderTexture LightRenderTarget { get; }
+
         IEye? Eye { get; set; }
         Vector2i Size { get; }
 
@@ -66,7 +67,7 @@ namespace Robust.Client.Graphics
         ///     Not relative to the current transform of <see cref="handle"/>.
         /// </param>
         public void RenderScreenOverlaysBelow(
-            DrawingHandleScreen handle,
+            IRenderHandle handle,
             IViewportControl control,
             in UIBox2i viewportBounds);
 
@@ -80,7 +81,7 @@ namespace Robust.Client.Graphics
         ///     Not relative to the current transform of <see cref="handle"/>.
         /// </param>
         public void RenderScreenOverlaysAbove(
-            DrawingHandleScreen handle,
+            IRenderHandle handle,
             IViewportControl control,
             in UIBox2i viewportBounds);
     }

Robust.Client/Graphics/IRenderTarget.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Numerics;
+using Robust.Shared.Graphics;
 using Robust.Shared.Maths;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -15,5 +17,42 @@ namespace Robust.Client.Graphics
         Vector2i Size { get; }
 
         void CopyPixelsToMemory<T>(CopyPixelsDelegate<T> callback, UIBox2i? subRegion = null) where T : unmanaged, IPixel<T>;
+
+        public Vector2 LocalToWorld(IEye eye, Vector2 point, Vector2 scale)
+        {
+            var newPoint = point;
+
+            // (inlined version of UiProjMatrix^-1)
+            newPoint -= Size / 2f;
+            newPoint *= new Vector2(1, -1) / EyeManager.PixelsPerMeter;
+
+            // view matrix
+            eye.GetViewMatrixInv(out var viewMatrixInv, scale);
+            newPoint = Vector2.Transform(newPoint, viewMatrixInv);
+
+            return newPoint;
+        }
+
+        public Vector2 WorldToLocal(Vector2 point, IEye eye, Vector2 scale)
+        {
+            var newPoint = point;
+
+            eye.GetViewMatrix(out var viewMatrix, scale);
+            newPoint = Vector2.Transform(newPoint, viewMatrix);
+
+            // (inlined version of UiProjMatrix)
+            newPoint *= new Vector2(1, -1) * EyeManager.PixelsPerMeter;
+            newPoint += Size / 2f;
+
+            return newPoint;
+        }
+
+        public Matrix3x2 GetWorldToLocalMatrix(IEye eye, Vector2 scale)
+        {
+            eye.GetViewMatrix(out var viewMatrix, scale * new Vector2(EyeManager.PixelsPerMeter, -EyeManager.PixelsPerMeter));
+            viewMatrix.M31 += Size.X / 2f;
+            viewMatrix.M32 += Size.Y / 2f;
+            return viewMatrix;
+        }
     }
 }

Robust.Client/Graphics/Lighting/GetClearColorEvent.cs

@@ -0,0 +1,13 @@
+using Robust.Shared.GameObjects;
+using Robust.Shared.Maths;
+
+namespace Robust.Client.Graphics;
+
+/// <summary>
+/// Raised by the engine if content wishes to override the default clear color.
+/// </summary>
+[ByRefEvent]
+public record struct GetClearColorEvent
+{
+    public Color? Color;
+}

Robust.Client/Graphics/Lighting/LightManager.cs

@@ -9,6 +9,5 @@ namespace Robust.Client.Graphics
         public bool DrawHardFov { get; set; } = true;
         public bool DrawLighting { get; set; } = true;
         public bool LockConsoleAccess { get; set; } = false;
-        public Color AmbientLightColor { get; set; } = Color.FromSrgb(Color.Black);
     }
 }

Robust.Client/Graphics/Overlays/OverlayDrawArgs.cs

@@ -1,6 +1,7 @@
 using JetBrains.Annotations;
 using Robust.Client.UserInterface.CustomControls;
 using Robust.Shared.Enums;
+using Robust.Shared.GameObjects;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
 
@@ -39,6 +40,8 @@ namespace Robust.Client.Graphics
         /// </summary>
         public readonly UIBox2i ViewportBounds;
 
+        public readonly EntityUid MapUid;
+
         /// <summary>
         /// <see cref="MapId"/> of the viewport's eye.
         /// </summary>
@@ -54,24 +57,32 @@ namespace Robust.Client.Graphics
         /// </summary>
         public readonly Box2Rotated WorldBounds;
 
+        public readonly IRenderHandle RenderHandle;
+
         public DrawingHandleScreen ScreenHandle => (DrawingHandleScreen) DrawingHandle;
         public DrawingHandleWorld WorldHandle => (DrawingHandleWorld) DrawingHandle;
 
-        public OverlayDrawArgs(
+        internal OverlayDrawArgs(
             OverlaySpace space,
             IViewportControl? viewportControl,
             IClydeViewport viewport,
-            DrawingHandleBase drawingHandle,
+            IRenderHandle renderHandle,
             in UIBox2i viewportBounds,
+            in EntityUid mapUid,
             in MapId mapId,
             in Box2 worldAabb,
             in Box2Rotated worldBounds)
         {
+            DrawingHandle = space is OverlaySpace.ScreenSpace or OverlaySpace.ScreenSpaceBelowWorld
+                ? renderHandle.DrawingHandleScreen
+                : renderHandle.DrawingHandleWorld;
+
             Space = space;
             ViewportControl = viewportControl;
             Viewport = viewport;
-            DrawingHandle = drawingHandle;
+            RenderHandle = renderHandle;
             ViewportBounds = viewportBounds;
+            MapUid = mapUid;
             MapId = mapId;
             WorldAABB = worldAabb;
             WorldBounds = worldBounds;

Robust.Client/Physics/PhysicsSystem.Predict.cs

@@ -93,7 +93,7 @@ public sealed partial class PhysicsSystem
         var maps = new HashSet<EntityUid>();
 
         var enumerator = AllEntityQuery<PredictedPhysicsComponent, PhysicsComponent, TransformComponent>();
-        while (enumerator.MoveNext(out var _, out var physics, out var xform))
+        while (enumerator.MoveNext(out _, out var physics, out var xform))
         {
             DebugTools.Assert(physics.Predict);
 

Robust.Client/Replays/Loading/ReplayLoadManager.Checkpoints.cs

@@ -352,6 +352,9 @@ public sealed partial class ReplayLoadManager
                 // prototype changes when jumping around in time. This also requires reworking how the initial
                 // implicit state data is generated, because we can't simply cache it anymore.
                 // Also, does reloading prototypes in release mode modify existing entities?
+                // Yes, yes it does. See PrototypeReloadSystem.UpdateEntity()
+                // Its just not supported ATM.
+                // TBH it'd be easier if overriding existing prototypes in release mode was just forbidden.
 
                 var msg = $"Overwriting an existing prototype! Kind: {kind.Name}. Ids: {string.Join(", ", ids)}";
                 if (_confMan.GetCVar(CVars.ReplayIgnoreErrors))
@@ -361,7 +364,6 @@ public sealed partial class ReplayLoadManager
             }
         }
 
-        _protoMan.ResolveResults();
         _protoMan.ReloadPrototypes(changed);
         _locMan.ReloadLocalizations();
     }

Robust.Client/Replays/Playback/ReplayPlaybackManager.Update.cs

@@ -44,8 +44,8 @@ internal sealed partial class ReplayPlaybackManager
             _gameState.UpdateFullRep(state, cloneDelta: true);
             var next = Replay.NextState;
             BeforeApplyState?.Invoke((state, next));
-            var created = _gameState.ApplyGameState(state, next);
-            _gameState.GenerateImplicitStates(created);
+            _gameState.ApplyGameState(state, next);
+            _gameState.MergeImplicitData();
             DebugTools.Assert(Replay.LastApplied >= state.FromSequence);
             DebugTools.Assert(Replay.LastApplied + 1 <= state.ToSequence);
             Replay.LastApplied = state.ToSequence;

Robust.Client/UserInterface/BoundUserInterfaceExt.cs

@@ -1,4 +1,5 @@
 using System;
+using Robust.Client.GameObjects;
 using Robust.Client.UserInterface.CustomControls;
 using Robust.Shared.GameObjects;
 
@@ -6,14 +7,63 @@ namespace Robust.Client.UserInterface;
 
 public static class BoundUserInterfaceExt
 {
+    private static T GetWindow<T>(BoundUserInterface bui) where T : BaseWindow, new()
+    {
+        var window = bui.CreateDisposableControl<T>();
+        window.OnClose += bui.Close;
+        var system = bui.EntMan.System<UserInterfaceSystem>();
+        system.RegisterControl(bui, window);
+        return window;
+    }
+
     /// <summary>
     /// Helper method to create a window and also handle closing the BUI when it's closed.
     /// </summary>
     public static T CreateWindow<T>(this BoundUserInterface bui) where T : BaseWindow, new()
     {
-        var window = bui.CreateDisposableControl<T>();
-        window.OpenCentered();
-        window.OnClose += bui.Close;
+        var window = GetWindow<T>(bui);
+
+        if (bui.EntMan.System<UserInterfaceSystem>().TryGetPosition(bui.Owner, bui.UiKey, out var position))
+        {
+            window.Open(position);
+        }
+        else
+        {
+            window.OpenCentered();
+        }
+
+        return window;
+    }
+
+    public static T CreateWindowCenteredLeft<T>(this BoundUserInterface bui) where T : BaseWindow, new()
+    {
+        var window = GetWindow<T>(bui);
+
+        if (bui.EntMan.System<UserInterfaceSystem>().TryGetPosition(bui.Owner, bui.UiKey, out var position))
+        {
+            window.Open(position);
+        }
+        else
+        {
+            window.OpenCenteredLeft();
+        }
+
+        return window;
+    }
+
+    public static T CreateWindowCenteredRight<T>(this BoundUserInterface bui) where T : BaseWindow, new()
+    {
+        var window = GetWindow<T>(bui);
+
+        if (bui.EntMan.System<UserInterfaceSystem>().TryGetPosition(bui.Owner, bui.UiKey, out var position))
+        {
+            window.Open(position);
+        }
+        else
+        {
+            window.OpenCenteredRight();
+        }
+
         return window;
     }
 

Robust.Client/UserInterface/Control.Styling.cs

@@ -128,7 +128,7 @@ namespace Robust.Client.UserInterface
             UserInterfaceManagerInternal.QueueStyleUpdate(this);
         }
 
-        internal void StyleSheetUpdate()
+        public void InvalidateStyleSheet()
         {
             _stylesheetUpdateNeeded = true;
 
@@ -137,7 +137,7 @@ namespace Robust.Client.UserInterface
 
         internal void StylesheetUpdateRecursive()
         {
-            StyleSheetUpdate();
+            InvalidateStyleSheet();
 
             foreach (var child in Children)
             {
@@ -149,7 +149,7 @@ namespace Robust.Client.UserInterface
             }
         }
 
-        internal void DoStyleUpdate()
+        public void DoStyleUpdate()
         {
             _styleProperties.Clear();
 

Robust.Client/UserInterface/Control.cs

@@ -549,7 +549,7 @@ namespace Robust.Client.UserInterface
         {
         }
 
-        internal virtual void DrawInternal(IRenderHandle renderHandle)
+        protected internal virtual void Draw(IRenderHandle renderHandle)
         {
             Draw(renderHandle.DrawingHandleScreen);
         }

Robust.Client/UserInterface/Controllers/Implementations/TileSpawningUIController.cs

@@ -87,7 +87,6 @@ public sealed class TileSpawningUIController : UIController
             return;
         _window = UIManager.CreateWindow<TileSpawnWindow>();
         LayoutContainer.SetAnchorPreset(_window,LayoutContainer.LayoutPreset.CenterLeft);
-        _window.SearchBar.GrabKeyboardFocus();
         _window.ClearButton.OnPressed += OnTileClearPressed;
         _window.SearchBar.OnTextChanged += OnTileSearchChanged;
         _window.TileList.OnItemSelected += OnTileItemSelected;

Robust.Client/UserInterface/Controls/EntityPrototypeView.cs

@@ -9,6 +9,7 @@ public class EntityPrototypeView : SpriteView
 {
     private string? _currentPrototype;
     private EntityUid? _ourEntity;
+    private bool _isShowing;
 
     public EntityPrototypeView()
     {
@@ -22,8 +23,6 @@ public class EntityPrototypeView : SpriteView
 
     public void SetPrototype(EntProtoId? entProto)
     {
-        SpriteSystem ??= EntMan.System<SpriteSystem>();
-
         if (entProto == _currentPrototype
             && EntMan.TryGetComponent(Entity?.Owner, out MetaDataComponent? meta)
             && meta.EntityPrototype?.ID == _currentPrototype)
@@ -32,14 +31,10 @@ public class EntityPrototypeView : SpriteView
         }
 
         _currentPrototype = entProto;
-        SetEntity(null);
-        EntMan.DeleteEntity(_ourEntity);
 
-        if (_currentPrototype != null)
+        if (_ourEntity != null || _isShowing)
         {
-            _ourEntity = EntMan.Spawn(_currentPrototype);
-            SpriteSystem.ForceUpdate(_ourEntity.Value);
-            SetEntity(_ourEntity);
+            UpdateEntity();
         }
     }
 
@@ -48,12 +43,38 @@ public class EntityPrototypeView : SpriteView
         base.EnteredTree();
 
         if (_currentPrototype != null)
-            SetPrototype(_currentPrototype);
+        {
+            UpdateEntity();
+        }
+
+        _isShowing = true;
     }
 
     protected override void ExitedTree()
     {
         base.ExitedTree();
         EntMan.TryQueueDeleteEntity(_ourEntity);
+        _ourEntity = null;
+
+        _isShowing = false;
+    }
+
+    private void UpdateEntity()
+    {
+        SetEntity(null);
+        EntMan.DeleteEntity(_ourEntity);
+
+        if (_currentPrototype != null)
+        {
+            SpriteSystem ??= EntMan.System<SpriteSystem>();
+
+            _ourEntity = EntMan.Spawn(_currentPrototype);
+            SpriteSystem.ForceUpdate(_ourEntity.Value);
+            SetEntity(_ourEntity);
+        }
+        else
+        {
+            _ourEntity = null;
+        }
     }
 }

Robust.Client/UserInterface/Controls/SpriteView.cs

@@ -224,7 +224,7 @@ namespace Robust.Client.UserInterface.Controls
             _spriteSize = new Vector2(longestRotatedSide, longestRotatedSide);
         }
 
-        internal override void DrawInternal(IRenderHandle renderHandle)
+        protected internal override void Draw(IRenderHandle renderHandle)
         {
             if (!ResolveEntity(out var uid, out var sprite, out var xform))
                 return;

Robust.Client/UserInterface/CustomControls/BaseWindow.cs

@@ -5,6 +5,7 @@ using Robust.Client.UserInterface.Controls;
 using Robust.Shared.Input;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
+using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Timing;
 
@@ -102,6 +103,8 @@ namespace Robust.Client.UserInterface.CustomControls
             {
                 var cursor = CursorShape.Arrow;
                 var previewDragMode = GetDragModeFor(args.RelativePosition);
+                previewDragMode &= ~DragMode.Move;
+
                 switch (previewDragMode)
                 {
                     case DragMode.Top:
@@ -116,9 +119,6 @@ namespace Robust.Client.UserInterface.CustomControls
 
                     case DragMode.Bottom | DragMode.Left:
                     case DragMode.Top | DragMode.Right:
-                        cursor = CursorShape.Crosshair;
-                        break;
-
                     case DragMode.Bottom | DragMode.Right:
                     case DragMode.Top | DragMode.Left:
                         cursor = CursorShape.Crosshair;
@@ -160,15 +160,6 @@ namespace Robust.Client.UserInterface.CustomControls
                 var rect = new UIBox2(left, top, right, bottom);
                 LayoutContainer.SetPosition(this, rect.TopLeft);
                 SetSize = rect.Size;
-
-                /*
-                var timing = IoCManager.Resolve<IGameTiming>();
-
-                var l = GetValue<float>(LayoutContainer.MarginLeftProperty);
-                var t = GetValue<float>(LayoutContainer.MarginTopProperty);
-
-                Logger.Debug($"{timing.CurFrame}: {rect.TopLeft}/({l}, {t}), {rect.Size}/{SetSize}");
-                */
             }
         }
 
@@ -229,6 +220,16 @@ namespace Robust.Client.UserInterface.CustomControls
             OnOpen?.Invoke();
         }
 
+        /// <summary>
+        /// Opens the window and places it at the specified position.
+        /// </summary>
+        public void Open(Vector2 position)
+        {
+            Measure(Vector2Helpers.Infinity);
+            Open();
+            LayoutContainer.SetPosition(this, position);
+        }
+
         public void OpenCentered() => OpenCenteredAt(new Vector2(0.5f, 0.5f));
 
         public void OpenToLeft() => OpenCenteredAt(new Vector2(0, 0.5f));

Robust.Client/UserInterface/CustomControls/TileSpawnWindow.xaml.cs

@@ -10,4 +10,11 @@ public sealed partial class TileSpawnWindow : DefaultWindow
     {
         RobustXamlLoader.Load(this);
     }
+
+    protected override void Opened()
+    {
+        base.Opened();
+        
+        SearchBar.GrabKeyboardFocus();
+    }
 }

Robust.Client/UserInterface/CustomControls/ViewportContainer.cs

@@ -65,13 +65,13 @@ namespace Robust.Client.UserInterface.CustomControls
 
         // -- Handlers: Out --
 
-        protected internal override void Draw(DrawingHandleScreen handle)
+        protected internal override void Draw(IRenderHandle handle)
         {
             base.Draw(handle);
 
             if (Viewport == null)
             {
-                handle.DrawRect(UIBox2.FromDimensions(new Vector2(0, 0), Size * UIScale), Color.Red);
+                handle.DrawingHandleScreen.DrawRect(UIBox2.FromDimensions(new Vector2(0, 0), Size * UIScale), Color.Red);
             }
             else
             {
@@ -82,7 +82,7 @@ namespace Robust.Client.UserInterface.CustomControls
                 Viewport.RenderScreenOverlaysBelow(handle, this, viewportBounds);
 
                 Viewport.Render();
-                handle.DrawTextureRect(Viewport.RenderTarget.Texture,
+                handle.DrawingHandleScreen.DrawTextureRect(Viewport.RenderTarget.Texture,
                     UIBox2.FromDimensions(new Vector2(0, 0), (Vector2i) (Viewport.Size / _viewportResolution)));
 
                 Viewport.RenderScreenOverlaysAbove(handle, this, viewportBounds);

Robust.Client/UserInterface/IUserInterfaceManager.cs

@@ -7,6 +7,7 @@ using Robust.Client.UserInterface.CustomControls;
 using Robust.Shared;
 using Robust.Shared.Audio.Sources;
 using Robust.Shared.Map;
+using Robust.Shared.Maths;
 
 namespace Robust.Client.UserInterface
 {
@@ -146,6 +147,16 @@ namespace Robust.Client.UserInterface
         /// but not necessarily a new or existing control is rearranged.
         /// </summary>
         void UpdateHovered();
+
+        /// <summary>
+        /// Render a control and all of its children.
+        /// </summary>
+        void RenderControl(in Control.ControlRenderArguments args, Control control);
+
+        /// <summary>
+        /// Render a control and all of its children.
+        /// </summary>
+        void RenderControl(IRenderHandle handle, Control control, Vector2i position);
     }
 
     public readonly struct PostDrawUIRootEventArgs

Robust.Client/UserInterface/UserInterfaceManager.Input.cs

@@ -313,7 +313,10 @@ internal partial class UserInterfaceManager
 
     private void _clearTooltip()
     {
-        if (!_showingTooltip) return;
+        _resetTooltipTimer();
+
+        if (!_showingTooltip)
+            return;
 
         if (_suppliedTooltip != null)
         {
@@ -322,7 +325,6 @@ internal partial class UserInterfaceManager
         }
 
         CurrentlyHovered?.PerformHideTooltip();
-        _resetTooltipTimer();
         _showingTooltip = false;
     }
 

Robust.Client/UserInterface/UserInterfaceManager.Roots.cs

@@ -37,7 +37,7 @@ internal sealed partial class UserInterfaceManager
         _roots.Add(newRoot);
         _windowsToRoot.Add(window.Id, newRoot);
 
-        newRoot.StyleSheetUpdate();
+        newRoot.InvalidateStyleSheet();
         newRoot.InvalidateMeasure();
         QueueMeasureUpdate(newRoot);
         QueueArrangeUpdate(newRoot);

Robust.Client/UserInterface/UserInterfaceManager.cs

@@ -335,6 +335,30 @@ namespace Robust.Client.UserInterface
             }
         }
 
+        public void RenderControl(in Control.ControlRenderArguments args, Control control)
+        {
+            var _ = 0;
+            RenderControl(args.Handle,
+                ref _,
+                control,
+                args.Position,
+                args.Modulate,
+                args.ScissorBox,
+                args.CoordinateTransform);
+        }
+
+        public void RenderControl(IRenderHandle handle, Control control, Vector2i position)
+        {
+            var _ = 0;
+            RenderControl(handle,
+                ref _,
+                control,
+                position,
+                Color.White,
+                null,
+                Matrix3x2.Identity);
+        }
+
         public void RenderControl(IRenderHandle renderHandle, ref int total, Control control, Vector2i position, Color modulate,
             UIBox2i? scissorBox, Matrix3x2 coordinateTransform)
         {
@@ -393,7 +417,7 @@ namespace Robust.Client.UserInterface
                 // Handle modulation with care.
                 var oldMod = handle.Modulate;
                 handle.Modulate = modulate * control.ActualModulateSelf;
-                control.DrawInternal(renderHandle);
+                control.Draw(renderHandle);
                 handle.Modulate = oldMod;
                 handle.UseShader(null);
             }
@@ -409,10 +433,11 @@ namespace Robust.Client.UserInterface
 
             control.PreRenderChildren(ref args);
 
-            foreach (var child in control.Children)
+            for (var index = 0; index < control.ChildCount; index++)
             {
+                var child = control.GetChild(index);
                 var pos = position + (Vector2i)Vector2.Transform(child.PixelPosition, coordinateTransform);
-                control.RenderChildOverride(ref args, child.GetPositionInParent(), pos);
+                control.RenderChildOverride(ref args, index, pos);
             }
 
             control.PostRenderChildren(ref args);

Robust.Serialization.Generator/Generator.cs

@@ -19,117 +19,112 @@ public class Generator : IIncrementalGenerator
 
     public void Initialize(IncrementalGeneratorInitializationContext initContext)
     {
-        IncrementalValuesProvider<TypeDeclarationSyntax> dataDefinitions = initContext.SyntaxProvider.CreateSyntaxProvider(
-            static (node, _) => node is TypeDeclarationSyntax,
-            static (context, _) =>
-            {
-                var type = (TypeDeclarationSyntax) context.Node;
-                var symbol = (ITypeSymbol) context.SemanticModel.GetDeclaredSymbol(type)!;
-                return IsDataDefinition(symbol) ? type : null;
-            }
-        ).Where(static type => type != null)!;
+        IncrementalValuesProvider<(string name, string code)?> dataDefinitions = initContext.SyntaxProvider
+            .CreateSyntaxProvider(
+                static (node, _) => node is TypeDeclarationSyntax,
+                static (context, _) =>
+                {
+                    var type = (TypeDeclarationSyntax)context.Node;
+                    var symbol = (ITypeSymbol)context.SemanticModel.GetDeclaredSymbol(type)!;
+                    if (!IsDataDefinition(symbol))
+                        return null;
+
+                    return GenerateForDataDefinition(type, symbol);
+                }
+            )
+            .Where(static type => type != null);
 
-        var comparer = new DataDefinitionComparer();
         initContext.RegisterSourceOutput(
-            initContext.CompilationProvider.Combine(dataDefinitions.WithComparer(comparer).Collect()),
+            dataDefinitions,
             static (sourceContext, source) =>
             {
-                var (compilation, declarations) = source;
-                var builder = new StringBuilder();
-                var containingTypes = new Stack<INamedTypeSymbol>();
-                var declarationsGenerated = new HashSet<string>();
-                var deltaType = compilation.GetTypeByMetadataName(ComponentDeltaInterfaceName)!;
+                // TODO: deduplicate based on name?
+                var (name, code) = source!.Value;
 
-                foreach (var declaration in declarations)
-                {
-                    builder.Clear();
-                    containingTypes.Clear();
-
-                    var type = compilation.GetSemanticModel(declaration.SyntaxTree).GetDeclaredSymbol(declaration)!;
-
-                    var symbolName = type
-                        .ToDisplayString()
-                        .Replace('<', '{')
-                        .Replace('>', '}');
-
-                    if (!declarationsGenerated.Add(symbolName))
-                        continue;
-
-                    var nonPartial = !IsPartial(declaration);
-
-                    var namespaceString = type.ContainingNamespace.IsGlobalNamespace
-                        ? string.Empty
-                        : $"namespace {type.ContainingNamespace.ToDisplayString()};";
-
-                    var containingType = type.ContainingType;
-                    while (containingType != null)
-                    {
-                        containingTypes.Push(containingType);
-                        containingType = containingType.ContainingType;
-                    }
-
-                    var containingTypesStart = new StringBuilder();
-                    var containingTypesEnd = new StringBuilder();
-                    foreach (var parent in containingTypes)
-                    {
-                        var syntax = (ClassDeclarationSyntax) parent.DeclaringSyntaxReferences[0].GetSyntax();
-                        if (!IsPartial(syntax))
-                        {
-                            nonPartial = true;
-                            continue;
-                        }
-
-                        containingTypesStart.AppendLine($"{GetPartialTypeDefinitionLine(parent)}\n{{");
-                        containingTypesEnd.AppendLine("}");
-                    }
-
-                    var definition = GetDataDefinition(type);
-                    if (nonPartial || definition.InvalidFields)
-                        continue;
-
-                    builder.AppendLine($$"""
-#nullable enable
-using System;
-using Robust.Shared.Analyzers;
-using Robust.Shared.IoC;
-using Robust.Shared.GameObjects;
-using Robust.Shared.Serialization;
-using Robust.Shared.Serialization.Manager;
-using Robust.Shared.Serialization.Manager.Exceptions;
-using Robust.Shared.Serialization.TypeSerializers.Interfaces;
-#pragma warning disable CS0618 // Type or member is obsolete
-#pragma warning disable CS0612 // Type or member is obsolete
-#pragma warning disable CS0108 // Member hides inherited member; missing new keyword
-#pragma warning disable RA0002 // Robust access analyzer
-
-{{namespaceString}}
-
-{{containingTypesStart}}
-
-{{GetPartialTypeDefinitionLine(type)}} : ISerializationGenerated<{{definition.GenericTypeName}}>
-{
-    {{GetConstructor(definition)}}
-
-    {{GetCopyMethods(definition, deltaType)}}
-
-    {{GetInstantiators(definition, deltaType)}}
-}
-
-{{containingTypesEnd}}
-""");
-
-                    var sourceText = CSharpSyntaxTree
-                        .ParseText(builder.ToString())
-                        .GetRoot()
-                        .NormalizeWhitespace()
-                        .ToFullString();
-
-                    sourceContext.AddSource($"{symbolName}.g.cs", sourceText);
-                }
+                sourceContext.AddSource(name, code);
             }
         );
     }
 
+    private static (string, string)? GenerateForDataDefinition(
+        TypeDeclarationSyntax declaration,
+        ITypeSymbol type)
+    {
+        var builder = new StringBuilder();
+        var containingTypes = new Stack<INamedTypeSymbol>();
+        containingTypes.Clear();
+
+        var symbolName = type
+            .ToDisplayString()
+            .Replace('<', '{')
+            .Replace('>', '}');
+
+        var nonPartial = !IsPartial(declaration);
+
+        var namespaceString = type.ContainingNamespace.IsGlobalNamespace
+            ? string.Empty
+            : $"namespace {type.ContainingNamespace.ToDisplayString()};";
+
+        var containingType = type.ContainingType;
+        while (containingType != null)
+        {
+            containingTypes.Push(containingType);
+            containingType = containingType.ContainingType;
+        }
+
+        var containingTypesStart = new StringBuilder();
+        var containingTypesEnd = new StringBuilder();
+        foreach (var parent in containingTypes)
+        {
+            var syntax = (ClassDeclarationSyntax)parent.DeclaringSyntaxReferences[0].GetSyntax();
+            if (!IsPartial(syntax))
+            {
+                nonPartial = true;
+                continue;
+            }
+
+            containingTypesStart.AppendLine($"{GetPartialTypeDefinitionLine(parent)}\n{{");
+            containingTypesEnd.AppendLine("}");
+        }
+
+        var definition = GetDataDefinition(type);
+        if (nonPartial || definition.InvalidFields)
+            return null;
+
+        builder.AppendLine($$"""
+            #nullable enable
+            using System;
+            using Robust.Shared.Analyzers;
+            using Robust.Shared.IoC;
+            using Robust.Shared.GameObjects;
+            using Robust.Shared.Serialization;
+            using Robust.Shared.Serialization.Manager;
+            using Robust.Shared.Serialization.Manager.Exceptions;
+            using Robust.Shared.Serialization.TypeSerializers.Interfaces;
+            #pragma warning disable CS0618 // Type or member is obsolete
+            #pragma warning disable CS0612 // Type or member is obsolete
+            #pragma warning disable CS0108 // Member hides inherited member; missing new keyword
+            #pragma warning disable RA0002 // Robust access analyzer
+
+            {{namespaceString}}
+
+            {{containingTypesStart}}
+
+            {{GetPartialTypeDefinitionLine(type)}} : ISerializationGenerated<{{definition.GenericTypeName}}>
+            {
+                {{GetConstructor(definition)}}
+
+                {{GetCopyMethods(definition)}}
+
+                {{GetInstantiators(definition)}}
+            }
+
+            {{containingTypesEnd}}
+            """);
+
+        return ($"{symbolName}.g.cs", builder.ToString());
+    }
+
     private static DataDefinition GetDataDefinition(ITypeSymbol definition)
     {
         var fields = new List<DataField>();
@@ -196,7 +191,7 @@ using Robust.Shared.Serialization.TypeSerializers.Interfaces;
          return builder.ToString();
      }
 
-    private static string GetCopyMethods(DataDefinition definition, ITypeSymbol deltaType)
+    private static string GetCopyMethods(DataDefinition definition)
     {
         var builder = new StringBuilder();
 
@@ -267,36 +262,36 @@ using Robust.Shared.Serialization.TypeSerializers.Interfaces;
                              {{baseCopy}}
                              """);
 
-        foreach (var @interface in InternalGetImplicitDataDefinitionInterfaces(definition.Type, true, deltaType))
+        foreach (var interfaceName in InternalGetImplicitDataDefinitionInterfaces(definition.Type, true))
         {
-            var interfaceModifiers = baseType != null && baseType.AllInterfaces.Contains(@interface, SymbolEqualityComparer.Default)
+            var interfaceModifiers = baseType != null &&
+                                     baseType.AllInterfaces.Any(i => i.ToDisplayString() == interfaceName)
                 ? "override "
                 : modifiers;
-            var interfaceName = @interface.ToDisplayString();
 
             builder.AppendLine($$"""
-                                 /// <seealso cref="ISerializationManager.CopyTo"/>
-                                 [Obsolete("Use ISerializationManager.CopyTo instead")]
-                                 public {{interfaceModifiers}} void InternalCopy(ref {{interfaceName}} target, ISerializationManager serialization, SerializationHookContext hookCtx, ISerializationContext? context = null)
-                                 {
-                                     var def = ({{definition.GenericTypeName}}) target;
-                                     Copy(ref def, serialization, hookCtx, context);
-                                     target = def;
-                                 }
+                /// <seealso cref="ISerializationManager.CopyTo"/>
+                [Obsolete("Use ISerializationManager.CopyTo instead")]
+                public {{interfaceModifiers}} void InternalCopy(ref {{interfaceName}} target, ISerializationManager serialization, SerializationHookContext hookCtx, ISerializationContext? context = null)
+                {
+                    var def = ({{definition.GenericTypeName}}) target;
+                    Copy(ref def, serialization, hookCtx, context);
+                    target = def;
+                }
 
-                                 /// <seealso cref="ISerializationManager.CopyTo"/>
-                                 [Obsolete("Use ISerializationManager.CopyTo instead")]
-                                 public {{interfaceModifiers}} void Copy(ref {{interfaceName}} target, ISerializationManager serialization, SerializationHookContext hookCtx, ISerializationContext? context = null)
-                                 {
-                                     InternalCopy(ref target, serialization, hookCtx, context);
-                                 }
-                                 """);
+                /// <seealso cref="ISerializationManager.CopyTo"/>
+                [Obsolete("Use ISerializationManager.CopyTo instead")]
+                public {{interfaceModifiers}} void Copy(ref {{interfaceName}} target, ISerializationManager serialization, SerializationHookContext hookCtx, ISerializationContext? context = null)
+                {
+                    InternalCopy(ref target, serialization, hookCtx, context);
+                }
+                """);
         }
 
         return builder.ToString();
     }
 
-    private static string GetInstantiators(DataDefinition definition, ITypeSymbol deltaType)
+    private static string GetInstantiators(DataDefinition definition)
     {
         var builder = new StringBuilder();
         var modifiers = string.Empty;
@@ -330,27 +325,28 @@ using Robust.Shared.Serialization.TypeSerializers.Interfaces;
                                  """);
         }
 
-        foreach (var @interface in InternalGetImplicitDataDefinitionInterfaces(definition.Type, false, deltaType))
+        foreach (var interfaceName in InternalGetImplicitDataDefinitionInterfaces(definition.Type, false))
         {
-            var interfaceName = @interface.ToDisplayString();
             builder.AppendLine($$"""
-                                 {{interfaceName}} {{interfaceName}}.Instantiate()
-                                 {
-                                     return Instantiate();
-                                 }
+                {{interfaceName}} {{interfaceName}}.Instantiate()
+                {
+                    return Instantiate();
+                }
 
-                                 {{interfaceName}} ISerializationGenerated<{{interfaceName}}>.Instantiate()
-                                 {
-                                     return Instantiate();
-                                 }
-                                 """);
+                {{interfaceName}} ISerializationGenerated<{{interfaceName}}>.Instantiate()
+                {
+                    return Instantiate();
+                }
+                """);
         }
 
         return builder.ToString();
     }
 
     [SuppressMessage("ReSharper", "PossibleMultipleEnumeration")]
-    private static IEnumerable<ITypeSymbol> InternalGetImplicitDataDefinitionInterfaces(ITypeSymbol type, bool all, ITypeSymbol deltaType)
+    private static IEnumerable<string> InternalGetImplicitDataDefinitionInterfaces(
+        ITypeSymbol type,
+        bool all)
     {
         var symbols = GetImplicitDataDefinitionInterfaces(type, all);
 
@@ -368,10 +364,10 @@ using Robust.Shared.Serialization.TypeSerializers.Interfaces;
             return symbols;
         }
 
-        if (symbols.Any(x => x.ToDisplayString() == deltaType.ToDisplayString()))
+        if (symbols.Any(x => x == ComponentDeltaInterfaceName))
             return symbols;
 
-        return symbols.Append(deltaType);
+        return symbols.Append(ComponentDeltaInterfaceName);
     }
 
     // TODO serveronly? do we care? who knows!!

Robust.Serialization.Generator/Types.cs

@@ -1,4 +1,5 @@
-using System.Diagnostics.CodeAnalysis;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
@@ -93,13 +94,13 @@ internal static class Types
         return false;
     }
 
-    internal static IEnumerable<ITypeSymbol> GetImplicitDataDefinitionInterfaces(ITypeSymbol type, bool all)
+    internal static IEnumerable<string> GetImplicitDataDefinitionInterfaces(ITypeSymbol type, bool all)
     {
         var interfaces = all ? type.AllInterfaces : type.Interfaces;
         foreach (var @interface in interfaces)
         {
             if (IsImplicitDataDefinitionInterface(@interface))
-                yield return @interface;
+                yield return @interface.ToDisplayString();
         }
     }
 

Robust.Server/BaseServer.cs

@@ -297,7 +297,7 @@ namespace Robust.Server
                 : null;
 
             // Set up the VFS
-            _resources.Initialize(dataDir);
+            _resources.Initialize(dataDir, hideUserDataDir: false);
 
             var mountOptions = _commandLineArgs != null
                 ? MountOptions.Merge(_commandLineArgs.MountOptions, Options.MountOptions) : Options.MountOptions;

Robust.Server/GameStates/PvsData.cs

@@ -20,6 +20,10 @@ namespace Robust.Server.GameStates;
 /// </summary>
 internal sealed class PvsSession(ICommonSession session, ResizableMemoryRegion<PvsData> memoryRegion)
 {
+#if DEBUG
+    public HashSet<NetEntity> ToSendSet = new();
+#endif
+
     public readonly ICommonSession Session = session;
 
     public readonly ResizableMemoryRegion<PvsData> DataMemory = memoryRegion;
@@ -197,7 +201,7 @@ internal struct PvsMetadata
     {
         DebugTools.AssertEqual(NetEntity, comp.NetEntity);
         DebugTools.AssertEqual(VisMask, comp.VisibilityMask);
-        DebugTools.AssertEqual(LifeStage, comp.EntityLifeStage);
+        DebugTools.Assert(LifeStage == comp.EntityLifeStage);
         DebugTools.Assert(LastModifiedTick == comp.EntityLastModifiedTick || LastModifiedTick.Value == 0);
     }
 }

Robust.Server/GameStates/PvsOverrideSystem.cs

@@ -5,13 +5,14 @@ using Robust.Server.Player;
 using Robust.Shared.Console;
 using Robust.Shared.Enums;
 using Robust.Shared.GameObjects;
+using Robust.Shared.GameStates;
 using Robust.Shared.IoC;
 using Robust.Shared.Player;
 using Robust.Shared.Utility;
 
 namespace Robust.Server.GameStates;
 
-public sealed class PvsOverrideSystem : EntitySystem
+public sealed class PvsOverrideSystem : SharedPvsOverrideSystem
 {
     [Dependency] private readonly IPlayerManager _player = default!;
     [Dependency] private readonly IConsoleHost _console = default!;
@@ -134,8 +135,10 @@ public sealed class PvsOverrideSystem : EntitySystem
     /// Forces the entity, all of its parents, and all of its children to ignore normal PVS range limitations,
     /// causing them to always be sent to all clients.
     /// </summary>
-    public void AddGlobalOverride(EntityUid uid)
+    public override void AddGlobalOverride(EntityUid uid)
     {
+        base.AddGlobalOverride(uid);
+
         if (GlobalOverride.Add(uid))
             _hasOverride.Add(uid);
     }
@@ -143,8 +146,10 @@ public sealed class PvsOverrideSystem : EntitySystem
     /// <summary>
     /// Removes an entity from the global overrides.
     /// </summary>
-    public void RemoveGlobalOverride(EntityUid uid)
+    public override void RemoveGlobalOverride(EntityUid uid)
     {
+        base.RemoveGlobalOverride(uid);
+
         GlobalOverride.Remove(uid);
         // Not bothering to clear _hasOverride, as we'd have to check all the other collections, and at that point we
         // might as well just do that when the entity gets deleted anyways.
@@ -203,8 +208,10 @@ public sealed class PvsOverrideSystem : EntitySystem
     /// Forces the entity, all of its parents, and all of its children to ignore normal PVS range limitations for a
     /// specific session.
     /// </summary>
-    public void AddSessionOverride(EntityUid uid, ICommonSession session)
+    public override void AddSessionOverride(EntityUid uid, ICommonSession session)
     {
+        base.AddSessionOverride(uid, session);
+
         if (SessionOverrides.GetOrNew(session).Add(uid))
             _hasOverride.Add(uid);
     }
@@ -212,8 +219,10 @@ public sealed class PvsOverrideSystem : EntitySystem
     /// <summary>
     /// Removes an entity from a session's overrides.
     /// </summary>
-    public void RemoveSessionOverride(EntityUid uid, ICommonSession session)
+    public override void RemoveSessionOverride(EntityUid uid, ICommonSession session)
     {
+        base.RemoveSessionOverride(uid, session);
+
         if (!SessionOverrides.TryGetValue(session, out var overrides))
             return;
 
@@ -228,8 +237,10 @@ public sealed class PvsOverrideSystem : EntitySystem
     /// Forces the entity, all of its parents, and all of its children to ignore normal PVS range limitations,
     /// causing them to always be sent to all clients.
     /// </summary>
-    public void AddSessionOverrides(EntityUid uid, Filter filter)
+    public override void AddSessionOverrides(EntityUid uid, Filter filter)
     {
+        base.AddSessionOverrides(uid, filter);
+
         foreach (var session in filter.Recipients)
         {
             AddSessionOverride(uid, session);

Robust.Server/GameStates/PvsSystem.cs

@@ -302,7 +302,9 @@ internal sealed partial class PvsSystem : EntitySystem
         // Process all entities in visible PVS chunks
         AddPvsChunks(session);
 
+#if DEBUG
         VerifySessionData(session);
+#endif
 
         var toSend = session.ToSend!;
         session.ToSend = null;
@@ -332,11 +334,12 @@ internal sealed partial class PvsSystem : EntitySystem
         session.Overflow = oldEntry.Value;
     }
 
-    [Conditional("DEBUG")]
+#if DEBUG
     private void VerifySessionData(PvsSession pvsSession)
     {
-        var toSend = pvsSession.ToSend;
-        var toSendSet = new HashSet<NetEntity>(toSend!.Count);
+        var toSend = pvsSession.ToSend!;
+        var toSendSet = pvsSession.ToSendSet;
+        toSendSet.Clear();
 
         foreach (var intPtr in toSend)
         {
@@ -360,6 +363,7 @@ internal sealed partial class PvsSystem : EntitySystem
                               || data.LastSeen == _gameTiming.CurTick - 1);
         }
     }
+#endif
 
     private (Vector2 worldPos, float range, EntityUid? map) CalcViewBounds(Entity<TransformComponent, EyeComponent?> eye)
     {

Robust.Server/Maps/MapChunkSerializer.cs

@@ -73,7 +73,7 @@ internal sealed class MapChunkSerializer : ITypeSerializer<MapChunk, MappingData
             for (ushort x = 0; x < chunk.ChunkSize; x++)
             {
                 var id = version < 6 ? reader.ReadUInt16() : reader.ReadInt32();
-                var flags = (TileRenderFlag)reader.ReadByte();
+                var flags = reader.ReadByte();
                 var variant = reader.ReadByte();
 
                 var defName = tileMap[id];

Robust.Server/Upload/GamePrototypeLoadManager.cs

@@ -50,6 +50,9 @@ public sealed class GamePrototypeLoadManager : SharedPrototypeLoadManager
 
     internal void SendToNewUser(INetChannel channel)
     {
+        if (LoadedPrototypes.Count == 0)
+            return;
+
         // Just dump all the prototypes on connect, before them missing could be an issue.
         var msg = new GamePrototypeLoadMessage
         {

Robust.Shared.Maths/Angle.cs

@@ -39,7 +39,6 @@ namespace Robust.Shared.Maths
         /// <param name="dir"></param>
         public Angle(Vector2 dir)
         {
-            dir = dir.Normalized();
             Theta = Math.Atan2(dir.Y, dir.X);
         }
 

Robust.Shared.Maths/Properties/AssemblyInfo.cs

@@ -6,4 +6,3 @@
 
 [assembly: InternalsVisibleTo("Robust.Client")]
 [assembly: InternalsVisibleTo("Robust.UnitTesting")]
-[assembly: InternalsVisibleTo("Content.Benchmarks")]

Robust.Shared/Audio/Systems/SharedAudioSystem.cs

@@ -37,6 +37,8 @@ public abstract partial class SharedAudioSystem : EntitySystem
     [Dependency] protected readonly MetaDataSystem MetadataSys = default!;
     [Dependency] protected readonly SharedTransformSystem XformSystem = default!;
 
+    private const float AudioDespawnBuffer = 1f;
+
     /// <summary>
     /// Default max range at which the sound can be heard.
     /// </summary>
@@ -234,7 +236,7 @@ public abstract partial class SharedAudioSystem : EntitySystem
                 {
                     var timed = EnsureComp<TimedDespawnComponent>(entity.Value);
                     var audioLength = GetAudioLength(component.FileName);
-                    timed.Lifetime = (float) audioLength.TotalSeconds + 0.01f;
+                    timed.Lifetime = (float) audioLength.TotalSeconds + AudioDespawnBuffer;
                 }
                 break;
         }
@@ -322,7 +324,7 @@ public abstract partial class SharedAudioSystem : EntitySystem
 
             var despawn = AddComp<TimedDespawnComponent>(uid);
             // Don't want to clip audio too short due to imprecision.
-            despawn.Lifetime = (float) length.Value.TotalSeconds + 0.01f;
+            despawn.Lifetime = (float) length.Value.TotalSeconds + AudioDespawnBuffer;
         }
 
         if (comp.Params.Variation != null && comp.Params.Variation.Value != 0f)

Robust.Shared/CVars.cs

@@ -1349,10 +1349,10 @@ namespace Robust.Shared
         /// MaxLinVelocity is compared to the dot product of linearVelocity * frameTime.
         /// </summary>
         /// <remarks>
-        /// Default is 35 m/s. Around half a tile per tick at 60 ticks per second.
+        /// Default is 400 m/s in-line with Box2c. Box2d used 120m/s.
         /// </remarks>
         public static readonly CVarDef<float> MaxLinVelocity =
-            CVarDef.Create("physics.maxlinvelocity", 35f, CVar.SERVER | CVar.REPLICATED);
+            CVarDef.Create("physics.maxlinvelocity", 400f, CVar.SERVER | CVar.REPLICATED);
 
         /// <summary>
         /// Maximum angular velocity in full rotations per second.
@@ -1364,7 +1364,6 @@ namespace Robust.Shared
         public static readonly CVarDef<float> MaxAngVelocity =
             CVarDef.Create("physics.maxangvelocity", 15f);
 
-
         /*
          * User interface
          */

Robust.Shared/Configuration/ConfigurationCommands.cs

@@ -8,6 +8,58 @@ using Robust.Shared.Utility;
 
 namespace Robust.Shared.Configuration
 {
+    public static class CVarCommandUtil
+    {
+        /// <summary>
+        /// Parses a string into an object of the given type.
+        /// </summary>
+        /// <exception cref="FormatException">Thrown if the string could not be parsed into the given type.</exception>
+        /// <exception cref="NotSupportedException">Thrown if the type is not supported.</exception>
+        public static object ParseObject(Type type, string input)
+        {
+            if (type == typeof(bool))
+            {
+                if (bool.TryParse(input, out var val))
+                    return val;
+
+                if (Parse.TryInt32(input, out var intVal))
+                {
+                    if (intVal == 0) return false;
+                    if (intVal == 1) return true;
+                }
+
+                throw new FormatException($"Could not parse bool value: {input}");
+            }
+
+            if (type == typeof(string))
+            {
+                return input;
+            }
+
+            if (type == typeof(int))
+            {
+                return Parse.Int32(input);
+            }
+
+            if (type == typeof(float))
+            {
+                return Parse.Float(input);
+            }
+
+            if (type == typeof(long))
+            {
+                return long.Parse(input);
+            }
+
+            if (type == typeof(ushort))
+            {
+                return ushort.Parse(input);
+            }
+
+            throw new NotSupportedException();
+        }
+    }
+
     [SuppressMessage("ReSharper", "StringLiteralTypo")]
     internal sealed class CVarCommand : LocalizedCommands
     {
@@ -51,7 +103,7 @@ namespace Robust.Shared.Configuration
                 var type = _cfg.GetCVarType(name);
                 try
                 {
-                    var parsed = ParseObject(type, value);
+                    var parsed = CVarCommandUtil.ParseObject(type, value);
                     _cfg.SetCVar(name, parsed);
                 }
                 catch (FormatException)
@@ -95,50 +147,6 @@ namespace Robust.Shared.Configuration
 
             return value;
         }
-
-        private static object ParseObject(Type type, string input)
-        {
-            if (type == typeof(bool))
-            {
-                if (bool.TryParse(input, out var val))
-                    return val;
-
-                if (Parse.TryInt32(input, out var intVal))
-                {
-                    if (intVal == 0) return false;
-                    if (intVal == 1) return true;
-                }
-
-                throw new FormatException($"Could not parse bool value: {input}");
-            }
-
-            if (type == typeof(string))
-            {
-                return input;
-            }
-
-            if (type == typeof(int))
-            {
-                return Parse.Int32(input);
-            }
-
-            if (type == typeof(float))
-            {
-                return Parse.Float(input);
-            }
-
-            if (type == typeof(long))
-            {
-                return long.Parse(input);
-            }
-
-            if (type == typeof(ushort))
-            {
-                return ushort.Parse(input);
-            }
-
-            throw new NotSupportedException();
-        }
     }
 
     internal sealed class CVarSubsCommand : LocalizedCommands

Robust.Shared/Containers/SharedContainerSystem.Insert.cs

@@ -197,6 +197,10 @@ public abstract partial class SharedContainerSystem
     {
         if (entity.Comp2 is { } physics)
         {
+            // TODO CONTAINER
+            // Is this actually needed?
+            // I.e., shouldn't this just do a if (_timing.ApplyingState) return
+
             // Here we intentionally don't dirty the physics comp. Client-side state handling will apply these same
             // changes. This also ensures that the server doesn't have to send the physics comp state to every
             // player for any entity inside of a container during init.

Robust.Shared/ContentPack/AssemblyTypeChecker.Config.cs

@@ -88,6 +88,7 @@ namespace Robust.Shared.ContentPack
             public string SystemAssemblyName = default!;
             public HashSet<VerifierError> AllowedVerifierErrors = default!;
             public List<string> WhitelistedNamespaces = default!;
+            public List<string> AllowedAssemblyPrefixes = default!;
             public Dictionary<string, Dictionary<string, TypeConfig>> Types = default!;
         }
 

Robust.Shared/ContentPack/AssemblyTypeChecker.cs

@@ -131,6 +131,16 @@ namespace Robust.Shared.ContentPack
                 return false;
             }
 
+#pragma warning disable RA0004
+            var loadedConfig = _config.Result;
+#pragma warning restore RA0004
+
+            if (!loadedConfig.AllowedAssemblyPrefixes.Any(allowedNamePrefix => asmName.StartsWith(allowedNamePrefix)))
+            {
+                _sawmill.Error($"Assembly name '{asmName}' is not allowed for a content assembly");
+                return false;
+            }
+
             if (VerifyIL)
             {
                 if (!DoVerifyIL(asmName, resolver, peReader, reader))
@@ -179,10 +189,6 @@ namespace Robust.Shared.ContentPack
                 return true;
             }
 
-#pragma warning disable RA0004
-            var loadedConfig = _config.Result;
-#pragma warning restore RA0004
-
             var badRefs = new ConcurrentBag<EntityHandle>();
 
             // We still do explicit type reference scanning, even though the actual whitelists work with raw members.

Robust.Shared/ContentPack/DirLoader.cs

@@ -60,7 +60,7 @@ namespace Robust.Shared.ContentPack
 
             internal string GetPath(ResPath relPath)
             {
-                return Path.GetFullPath(Path.Combine(_directory.FullName, relPath.ToRelativeSystemPath()));
+                return PathHelpers.SafeGetResourcePath(_directory.FullName, relPath);
             }
 
             /// <inheritdoc />

Robust.Shared/ContentPack/IResourceManagerInternal.cs

@@ -14,7 +14,11 @@ namespace Robust.Shared.ContentPack
         /// The directory to use for user data.
         /// If null, a virtual temporary file system is used instead.
         /// </param>
-        void Initialize(string? userData);
+        /// <param name="hideUserDataDir">
+        /// If true, <see cref="IWritableDirProvider.RootDir"/> will be hidden on
+        /// <see cref="IResourceManager.UserData"/>.
+        /// </param>
+        void Initialize(string? userData, bool hideUserDataDir);
 
         /// <summary>
         ///     Mounts a single stream as a content file. Useful for unit testing.

Robust.Shared/ContentPack/IWritableDirProvider.cs

@@ -13,7 +13,7 @@ namespace Robust.Shared.ContentPack
     {
         /// <summary>
         /// The root path of this provider.
-        /// Can be null if it's a virtual provider.
+        /// Can be null if it's a virtual provider or the path is protected (e.g. on the client).
         /// </summary>
         string? RootDir { get; }
 

Robust.Shared/ContentPack/ModLoader.cs

@@ -93,19 +93,23 @@ namespace Robust.Shared.ContentPack
         {
             var sw = Stopwatch.StartNew();
             Sawmill.Debug("LOADING modules");
-            var files = new Dictionary<string, (ResPath Path, string[] references)>();
+            var files = new Dictionary<string, (ResPath Path, MemoryStream data, string[] references)>();
 
             // Find all modules we want to load.
             foreach (var fullPath in paths)
             {
                 using var asmFile = _res.ContentFileRead(fullPath);
-                var refData = GetAssemblyReferenceData(asmFile);
+                var ms = new MemoryStream();
+                asmFile.CopyTo(ms);
+
+                ms.Position = 0;
+                var refData = GetAssemblyReferenceData(ms);
                 if (refData == null)
                     continue;
 
                 var (asmRefs, asmName) = refData.Value;
 
-                if (!files.TryAdd(asmName, (fullPath, asmRefs)))
+                if (!files.TryAdd(asmName, (fullPath, ms, asmRefs)))
                 {
                     Sawmill.Error("Found multiple modules with the same assembly name " +
                                   $"'{asmName}', A: {files[asmName].Path}, B: {fullPath}.");
@@ -122,10 +126,10 @@ namespace Robust.Shared.ContentPack
 
                 Parallel.ForEach(files, pair =>
                 {
-                    var (name, (path, _)) = pair;
+                    var (name, (_, data, _)) = pair;
 
-                    using var stream = _res.ContentFileRead(path);
-                    if (!typeChecker.CheckAssembly(stream, resolver))
+                    data.Position = 0;
+                    if (!typeChecker.CheckAssembly(data, resolver))
                     {
                         throw new TypeCheckFailedException($"Assembly {name} failed type checks.");
                     }
@@ -137,14 +141,15 @@ namespace Robust.Shared.ContentPack
             var nodes = TopologicalSort.FromBeforeAfter(
                 files,
                 kv => kv.Key,
-                kv => kv.Value.Path,
+                kv => kv.Value,
                 _ => 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 TopologicalSort.Sort(nodes))
+            foreach (var item in TopologicalSort.Sort(nodes))
             {
+                var (path, memory, _) = item;
                 Sawmill.Debug($"Loading module: '{path}'");
                 try
                 {
@@ -156,9 +161,9 @@ namespace Robust.Shared.ContentPack
                     }
                     else
                     {
-                        using var assemblyStream = _res.ContentFileRead(path);
+                        memory.Position = 0;
                         using var symbolsStream = _res.ContentFileReadOrNull(path.WithExtension("pdb"));
-                        LoadGameAssembly(assemblyStream, symbolsStream, skipVerify: true);
+                        LoadGameAssembly(memory, symbolsStream, skipVerify: true);
                     }
                 }
                 catch (Exception e)
@@ -174,7 +179,7 @@ namespace Robust.Shared.ContentPack
 
         private (string[] refs, string name)? GetAssemblyReferenceData(Stream stream)
         {
-            using var reader = ModLoader.MakePEReader(stream);
+            using var reader = ModLoader.MakePEReader(stream, leaveOpen: true);
             var metaReader = reader.GetMetadataReader();
 
             var name = metaReader.GetString(metaReader.GetAssemblyDefinition().Name);

Robust.Shared/ContentPack/PathHelpers.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Runtime.InteropServices;
+using Robust.Shared.Utility;
 
 namespace Robust.Shared.ContentPack
 {
@@ -63,5 +64,27 @@ namespace Robust.Shared.ContentPack
             !OperatingSystem.IsWindows()
             && !OperatingSystem.IsMacOS();
 
+
+        internal static string SafeGetResourcePath(string baseDir, ResPath path)
+        {
+            var relSysPath = path.ToRelativeSystemPath();
+            if (relSysPath.Contains("\\..") || relSysPath.Contains("/.."))
+            {
+                // Hard cap on any exploit smuggling a .. in there.
+                // Since that could allow leaving sandbox.
+                throw new InvalidOperationException($"This branch should never be reached. Path: {path}");
+            }
+
+            var retPath = Path.GetFullPath(Path.Join(baseDir, relSysPath));
+            // better safe than sorry check
+            if (!retPath.StartsWith(baseDir))
+            {
+                // Allow path to match if it's just missing the directory separator at the end.
+                if (retPath != baseDir.TrimEnd(Path.DirectorySeparatorChar))
+                    throw new InvalidOperationException($"This branch should never be reached. Path: {path}");
+            }
+
+            return retPath;
+        }
     }
 }

Robust.Shared/ContentPack/ResourceManager.cs

@@ -41,13 +41,13 @@ namespace Robust.Shared.ContentPack
         public IWritableDirProvider UserData { get; private set; } = default!;
 
         /// <inheritdoc />
-        public virtual void Initialize(string? userData)
+        public virtual void Initialize(string? userData, bool hideRootDir)
         {
             Sawmill = _logManager.GetSawmill("res");
 
             if (userData != null)
             {
-                UserData = new WritableDirProvider(Directory.CreateDirectory(userData));
+                UserData = new WritableDirProvider(Directory.CreateDirectory(userData), hideRootDir);
             }
             else
             {
@@ -379,7 +379,13 @@ namespace Robust.Shared.ContentPack
             {
                 if (root is DirLoader loader)
                 {
-                    yield return new ResPath(loader.GetPath(new ResPath(@"/")));
+                    var rootDir = loader.GetPath(new ResPath(@"/"));
+
+                    // TODO: GET RID OF THIS.
+                    // This code shouldn't be passing OS disk paths through ResPath.
+                    rootDir = rootDir.Replace(Path.DirectorySeparatorChar, '/');
+
+                    yield return new ResPath(rootDir);
                 }
             }
         }

Robust.Shared/ContentPack/Sandbox.yml

@@ -17,6 +17,10 @@ WhitelistedNamespaces:
 - Content
 - OpenDreamShared
 
+AllowedAssemblyPrefixes:
+- OpenDream
+- Content
+
 # The type whitelist does NOT care about which assembly types come from.
 # This is because types switch assembly all the time.
 # Just look up stuff like StreamReader on https://apisof.net.

Robust.Shared/ContentPack/WritableDirProvider.cs

@@ -10,17 +10,22 @@ namespace Robust.Shared.ContentPack
     /// <inheritdoc />
     internal sealed class WritableDirProvider : IWritableDirProvider
     {
-        /// <inheritdoc />
+        private readonly bool _hideRootDir;
+
         public string RootDir { get; }
 
+        string? IWritableDirProvider.RootDir => _hideRootDir ? null : RootDir;
+
         /// <summary>
         /// Constructs an instance of <see cref="WritableDirProvider"/>.
         /// </summary>
         /// <param name="rootDir">Root file system directory to allow writing.</param>
-        public WritableDirProvider(DirectoryInfo rootDir)
+        /// <param name="hideRootDir">If true, <see cref="IWritableDirProvider.RootDir"/> is reported as null.</param>
+        public WritableDirProvider(DirectoryInfo rootDir, bool hideRootDir)
         {
             // FullName does not have a trailing separator, and we MUST have a separator.
             RootDir = rootDir.FullName + Path.DirectorySeparatorChar.ToString();
+            _hideRootDir = hideRootDir;
         }
 
         #region File Access
@@ -119,7 +124,7 @@ namespace Robust.Shared.ContentPack
                 throw new FileNotFoundException();
 
             var dirInfo = new DirectoryInfo(GetFullPath(path));
-            return new WritableDirProvider(dirInfo);
+            return new WritableDirProvider(dirInfo, _hideRootDir);
         }
 
         /// <inheritdoc />
@@ -180,20 +185,7 @@ namespace Robust.Shared.ContentPack
 
             path = path.Clean();
 
-            return GetFullPath(RootDir, path);
-        }
-
-        private static string GetFullPath(string root, ResPath path)
-        {
-            var relPath = path.ToRelativeSystemPath();
-            if (relPath.Contains("\\..") || relPath.Contains("/.."))
-            {
-                // Hard cap on any exploit smuggling a .. in there.
-                // Since that could allow leaving sandbox.
-                throw new InvalidOperationException($"This branch should never be reached. Path: {path}");
-            }
-
-            return Path.GetFullPath(Path.Combine(root, relPath));
+            return PathHelpers.SafeGetResourcePath(RootDir, path);
         }
     }
 }

Robust.Shared/Enums/OverlaySpaces.cs

@@ -54,6 +54,11 @@ namespace Robust.Shared.Enums
         /// <summary>
         ///     Overlay will be rendered below grids, entities, and everything else. In world space.
         /// </summary>
-        WorldSpaceBelowWorld = 1 << 8
+        WorldSpaceBelowWorld = 1 << 8,
+
+        /// <summary>
+        /// Called after GLClear but before FOV applied to the lighting buffer.
+        /// </summary>
+        BeforeLighting = 1 << 9,
     }
 }

Robust.Shared/GameObjects/Components/UserInterface/BoundUserInterface.cs

@@ -11,10 +11,12 @@ namespace Robust.Shared.GameObjects
     /// </summary>
     public abstract class BoundUserInterface : IDisposable
     {
-        [Dependency] protected readonly IEntityManager EntMan = default!;
+        [Dependency] protected internal readonly IEntityManager EntMan = default!;
         [Dependency] protected readonly ISharedPlayerManager PlayerManager = default!;
         protected readonly SharedUserInterfaceSystem UiSystem;
 
+        public bool IsOpened { get; protected set; }
+
         public readonly Enum UiKey;
         public EntityUid Owner { get; }
 
@@ -28,13 +30,6 @@ namespace Robust.Shared.GameObjects
         /// </summary>
         protected internal BoundUserInterfaceState? State { get; internal set; }
 
-        // Bandaid just for storage :)
-        /// <summary>
-        /// Defers state handling
-        /// </summary>
-        [Obsolete]
-        public virtual bool DeferredClose { get; } = true;
-
         protected BoundUserInterface(EntityUid owner, Enum uiKey)
         {
             IoCManager.InjectDependencies(this);
@@ -48,8 +43,13 @@ namespace Robust.Shared.GameObjects
         ///     Invoked when the UI is opened.
         ///     Do all creation and opening of things like windows in here.
         /// </summary>
+        [MustCallBase]
         protected internal virtual void Open()
         {
+            if (IsOpened)
+                return;
+
+            IsOpened = true;
         }
 
         /// <summary>
@@ -100,6 +100,10 @@ namespace Robust.Shared.GameObjects
         /// </summary>
         public void Close()
         {
+            if (!IsOpened)
+                return;
+
+            IsOpened = false;
             UiSystem.CloseUi(Owner, UiKey, PlayerManager.LocalEntity, predicted: true);
         }
 

Robust.Shared/GameObjects/EntityManager.ComponentDeltas.cs

@@ -1,3 +1,4 @@
+using System;
 using Robust.Shared.Timing;
 
 namespace Robust.Shared.GameObjects;
@@ -38,11 +39,14 @@ public abstract partial class EntityManager
         Dirty(uid, comp, metadata);
     }
 
-    public void DirtyField<T>(EntityUid uid, T comp, string fieldName, MetaDataComponent? metadata = null)
+    public virtual void DirtyField<T>(EntityUid uid, T comp, string fieldName, MetaDataComponent? metadata = null)
         where T : IComponentDelta
     {
         var compReg = ComponentFactory.GetRegistration(CompIdx.Index<T>());
 
+        // TODO
+        // consider storing this on MetaDataComponent?
+        // We alsready store other dirtying information there anyways, and avoids having to fetch the registration.
         if (!compReg.NetworkedFieldLookup.TryGetValue(fieldName, out var idx))
         {
             _sawmill.Error($"Tried to dirty delta field {fieldName} on {ToPrettyString(uid)} that isn't implemented.");
@@ -54,6 +58,24 @@ public abstract partial class EntityManager
         comp.LastModifiedFields[idx] = curTick;
         Dirty(uid, comp, metadata);
     }
+
+    public virtual void DirtyFields<T>(EntityUid uid, T comp, MetaDataComponent? meta, params ReadOnlySpan<string> fields)
+        where T : IComponentDelta
+    {
+        var compReg = ComponentFactory.GetRegistration(CompIdx.Index<T>());
+
+        var curTick = _gameTiming.CurTick;
+        foreach (var field in fields)
+        {
+            if (!compReg.NetworkedFieldLookup.TryGetValue(field, out var idx))
+                _sawmill.Error($"Tried to dirty delta field {field} on {ToPrettyString(uid)} that isn't implemented.");
+            else
+                comp.LastModifiedFields[idx] = curTick;
+        }
+
+        comp.LastFieldUpdate = curTick;
+        Dirty(uid, comp, meta);
+    }
 }
 
 /// <summary>

Robust.Shared/GameObjects/EntityManager.Components.cs

@@ -197,17 +197,23 @@ namespace Robust.Shared.GameObjects
             {
                 var reg = _componentFactory.GetRegistration(name);
 
-                if (HasComponent(target, reg.Type))
+                if (removeExisting)
                 {
-                    if (!removeExisting)
-                        continue;
-
-                    RemoveComponent(target, reg.Type, metadata);
+                    var comp = _componentFactory.GetComponent(reg);
+                    _serManager.CopyTo(entry.Component, ref comp, notNullableOverride: true);
+                    AddComponentInternal(target, comp, reg, overwrite: true, metadata: metadata);
                 }
+                else
+                {
+                    if (HasComponent(target, reg))
+                    {
+                        continue;
+                    }
 
-                var comp = _componentFactory.GetComponent(reg);
-                _serManager.CopyTo(entry.Component, ref comp, notNullableOverride: true);
-                AddComponent(target, comp, metadata: metadata);
+                    var comp = _componentFactory.GetComponent(reg);
+                    _serManager.CopyTo(entry.Component, ref comp, notNullableOverride: true);
+                    AddComponentInternal(target, comp, reg, overwrite: false, metadata: metadata);
+                }
             }
         }
 
@@ -315,6 +321,22 @@ namespace Robust.Shared.GameObjects
             AddComponentInternal(uid, component, overwrite, false, metadata);
         }
 
+        private void AddComponentInternal<T>(
+            EntityUid uid,
+            T component,
+            ComponentRegistration compReg,
+            bool overwrite = false,
+            MetaDataComponent? metadata = null) where T : IComponent
+        {
+            if (!MetaQuery.Resolve(uid, ref metadata, false))
+                throw new ArgumentException($"Entity {uid} is not valid.", nameof(uid));
+
+            DebugTools.Assert(component.Owner == default);
+            component.Owner = uid;
+
+            AddComponentInternal(uid, component, compReg, overwrite, skipInit: false, metadata);
+        }
+
         private void AddComponentInternal<T>(EntityUid uid, T component, bool overwrite, bool skipInit, MetaDataComponent? metadata) where T : IComponent
         {
             if (!MetaQuery.ResolveInternal(uid, ref metadata, false))
@@ -731,6 +753,14 @@ namespace Robust.Shared.GameObjects
             return uid.HasValue && HasComponent<T>(uid.Value);
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        [Pure]
+        public bool HasComponent(EntityUid uid, ComponentRegistration reg)
+        {
+            var dict = _entTraitArray[reg.Idx.Value];
+            return dict.TryGetValue(uid, out var comp) && !comp.Deleted;
+        }
+
         /// <inheritdoc />
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         [Pure]
@@ -943,6 +973,23 @@ namespace Robust.Shared.GameObjects
             return false;
         }
 
+        /// <inheritdoc />
+        public bool TryGetComponent(EntityUid uid, ComponentRegistration reg, [NotNullWhen(true)] out IComponent? component)
+        {
+            var dict = _entTraitArray[reg.Idx.Value];
+            if (dict.TryGetValue(uid, out var comp))
+            {
+                if (!comp.Deleted)
+                {
+                    component = comp;
+                    return true;
+                }
+            }
+
+            component = null;
+            return false;
+        }
+
         /// <inheritdoc />
         public bool TryGetComponent(EntityUid uid, Type type, [NotNullWhen(true)] out IComponent? component)
         {
@@ -1694,7 +1741,6 @@ namespace Robust.Shared.GameObjects
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        [Pure]
         public bool Resolve(EntityUid uid, [NotNullWhen(true)] ref TComp1? component, bool logMissing = true)
         {
             if (component != null)
@@ -1717,7 +1763,7 @@ namespace Robust.Shared.GameObjects
             return false;
         }
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining), Pure]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public bool Resolve(ref Entity<TComp1?> entity, bool logMissing = true)
         {
             return Resolve(entity.Owner, ref entity.Comp, logMissing);

Robust.Shared/GameObjects/EntitySystem.Proxy.cs

@@ -171,6 +171,13 @@ public partial class EntitySystem
         EntityManager.DirtyField(uid, component, fieldName, meta);
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected void DirtyFields<T>(EntityUid uid, T comp, MetaDataComponent? meta, params ReadOnlySpan<string> fields)
+        where T : IComponentDelta
+    {
+        EntityManager.DirtyFields(uid, comp, meta);
+    }
+
     /// <summary>
     ///     Marks a component as dirty. This also implicitly dirties the entity this component belongs to.
     /// </summary>

Robust.Shared/GameObjects/IEntityManager.Components.cs

@@ -176,6 +176,14 @@ namespace Robust.Shared.GameObjects
         /// <returns>True if the entity has the component type, otherwise false.</returns>
         bool HasComponent<T>([NotNullWhen(true)] EntityUid? uid) where T : IComponent;
 
+        /// <summary>
+        ///     Checks if the entity has a component type.
+        /// </summary>
+        /// <param name="uid">Entity UID to check.</param>
+        /// <param name="reg">The component registration to check for.</param>
+        /// <returns>True if the entity has the component type, otherwise false.</returns>
+        bool HasComponent(EntityUid uid, ComponentRegistration reg);
+
         /// <summary>
         ///     Checks if the entity has a component type.
         /// </summary>
@@ -294,6 +302,15 @@ namespace Robust.Shared.GameObjects
         /// <returns>If the component existed in the entity.</returns>
         bool TryGetComponent<T>([NotNullWhen(true)] EntityUid? uid, [NotNullWhen(true)] out T? component) where T : IComponent?;
 
+        /// <summary>
+        ///     Returns the component of a specific type.
+        /// </summary>
+        /// <param name="uid">Entity UID to check.</param>
+        /// <param name="reg">The component registration to check for.</param>
+        /// <param name="component">Component of the specified type (if exists).</param>
+        /// <returns>If the component existed in the entity.</returns>
+        bool TryGetComponent(EntityUid uid, ComponentRegistration reg, [NotNullWhen(true)] out IComponent? component);
+
         /// <summary>
         ///     Returns the component of a specific type.
         /// </summary>

Robust.Shared/GameObjects/Systems/CollisionWakeSystem.cs

@@ -26,7 +26,7 @@ namespace Robust.Shared.GameObjects
 
         public void SetEnabled(EntityUid uid, bool enabled, CollisionWakeComponent? component = null)
         {
-            if (!_query.Resolve(uid, ref component) || component.Enabled == enabled)
+            if (!_query.Resolve(uid, ref component, false) || component.Enabled == enabled)
                 return;
 
             component.Enabled = enabled;

Robust.Shared/GameObjects/Systems/EntityLookup.Queries.cs

@@ -1,8 +1,6 @@
-using System;
 using System.Collections.Generic;
 using System.Numerics;
 using System.Runtime.CompilerServices;
-using JetBrains.Annotations;
 using Robust.Shared.Collections;
 using Robust.Shared.Map;
 using Robust.Shared.Map.Components;
@@ -11,7 +9,6 @@ using Robust.Shared.Physics;
 using Robust.Shared.Physics.Collision;
 using Robust.Shared.Physics.Collision.Shapes;
 using Robust.Shared.Physics.Dynamics;
-using Robust.Shared.Physics.Shapes;
 using Robust.Shared.Physics.Systems;
 using Robust.Shared.Utility;
 
@@ -77,14 +74,14 @@ public sealed partial class EntityLookupSystem
     /// <summary>
     /// Wrapper around the per-grid version.
     /// </summary>
-    private void AddEntitiesIntersecting(MapId mapId,
+    private void AddEntitiesIntersecting<T>(MapId mapId,
         HashSet<EntityUid> intersecting,
-        IPhysShape shape,
+        T shape,
         Transform shapeTransform,
-        LookupFlags flags)
+        LookupFlags flags) where T : IPhysShape
     {
         var worldAABB = shape.ComputeAABB(shapeTransform, 0);
-        var state = new EntityQueryState(intersecting,
+        var state = new EntityQueryState<T>(intersecting,
             shape,
             shapeTransform,
             _fixtures,
@@ -96,7 +93,7 @@ public sealed partial class EntityLookupSystem
 
         // Need to include maps
         _mapManager.FindGridsIntersecting(mapId, worldAABB, ref state,
-            static (EntityUid uid, MapGridComponent _, ref EntityQueryState state) =>
+            static (EntityUid uid, MapGridComponent _, ref EntityQueryState<T> state) =>
             {
                 var localTransform = state.Physics.GetRelativePhysicsTransform(state.Transform, uid);
                 var localAabb = state.Shape.ComputeAABB(localTransform, 0);
@@ -112,19 +109,19 @@ public sealed partial class EntityLookupSystem
         AddContained(intersecting, flags);
     }
 
-    private void AddEntitiesIntersecting(
+    private void AddEntitiesIntersecting<T>(
         EntityUid lookupUid,
         HashSet<EntityUid> intersecting,
-        IPhysShape shape,
+        T shape,
         Box2 localAABB,
         Transform localShapeTransform,
         LookupFlags flags,
-        BroadphaseComponent? lookup = null)
+        BroadphaseComponent? lookup = null) where T : IPhysShape
     {
         if (!_broadQuery.Resolve(lookupUid, ref lookup))
             return;
 
-        var state = new EntityQueryState(
+        var state = new EntityQueryState<T>(
             intersecting,
             shape,
             localShapeTransform,
@@ -157,7 +154,7 @@ public sealed partial class EntityLookupSystem
 
         return;
 
-        static bool PhysicsQuery(ref EntityQueryState state, in FixtureProxy value)
+        static bool PhysicsQuery(ref EntityQueryState<T> state, in FixtureProxy value)
         {
             var sensors = (state.Flags & LookupFlags.Sensors) != 0x0;
 
@@ -179,7 +176,7 @@ public sealed partial class EntityLookupSystem
             return true;
         }
 
-        static bool SundriesQuery(ref EntityQueryState state, in EntityUid value)
+        static bool SundriesQuery(ref EntityQueryState<T> state, in EntityUid value)
         {
             var approx = (state.Flags & LookupFlags.Approximate) != 0x0;
 
@@ -227,14 +224,14 @@ public sealed partial class EntityLookupSystem
     /// <summary>
     /// Wrapper around the per-grid version.
     /// </summary>
-    private bool AnyEntitiesIntersecting(MapId mapId,
-        IPhysShape shape,
+    private bool AnyEntitiesIntersecting<T>(MapId mapId,
+        T shape,
         Transform shapeTransform,
         LookupFlags flags,
-        EntityUid? ignored = null)
+        EntityUid? ignored = null) where T : IPhysShape
     {
         var worldAABB = shape.ComputeAABB(shapeTransform, 0);
-        var state = new AnyEntityQueryState(false,
+        var state = new AnyEntityQueryState<T>(false,
             ignored,
             shape,
             shapeTransform,
@@ -247,7 +244,7 @@ public sealed partial class EntityLookupSystem
 
         // Need to include maps
         _mapManager.FindGridsIntersecting(mapId, worldAABB, ref state,
-            static (EntityUid uid, MapGridComponent _, ref AnyEntityQueryState state) =>
+            static (EntityUid uid, MapGridComponent _, ref AnyEntityQueryState<T> state) =>
             {
                 var localTransform = state.Physics.GetRelativePhysicsTransform(state.Transform, uid);
                 var localAabb = state.Shape.ComputeAABB(localTransform, 0);
@@ -272,18 +269,18 @@ public sealed partial class EntityLookupSystem
         return state.Found;
     }
 
-    private bool AnyEntitiesIntersecting(EntityUid lookupUid,
-        IPhysShape shape,
+    private bool AnyEntitiesIntersecting<T>(EntityUid lookupUid,
+        T shape,
         Box2 localAABB,
         Transform shapeTransform,
         LookupFlags flags,
         EntityUid? ignored = null,
-        BroadphaseComponent? lookup = null)
+        BroadphaseComponent? lookup = null) where T : IPhysShape
     {
         if (!_broadQuery.Resolve(lookupUid, ref lookup))
             return false;
 
-        var state = new AnyEntityQueryState(false,
+        var state = new AnyEntityQueryState<T>(false,
             ignored,
             shape,
             shapeTransform,
@@ -325,7 +322,7 @@ public sealed partial class EntityLookupSystem
 
         return state.Found;
 
-        static bool PhysicsQuery(ref AnyEntityQueryState state, in FixtureProxy value)
+        static bool PhysicsQuery(ref AnyEntityQueryState<T> state, in FixtureProxy value)
         {
             if (state.Ignored == value.Entity)
                 return true;
@@ -350,7 +347,7 @@ public sealed partial class EntityLookupSystem
             return false;
         }
 
-        static bool SundriesQuery(ref AnyEntityQueryState state, in EntityUid value)
+        static bool SundriesQuery(ref AnyEntityQueryState<T> state, in EntityUid value)
         {
             if (state.Ignored == value)
                 return true;
@@ -409,9 +406,16 @@ public sealed partial class EntityLookupSystem
         var broadphaseInv = _transform.GetInvWorldMatrix(lookupUid);
 
         var localBounds = broadphaseInv.TransformBounds(worldBounds);
-        var shape = new Polygon(localBounds);
+        var polygon = _physics.GetPooled(localBounds);
+        var result = AnyEntitiesIntersecting(lookupUid,
+            polygon,
+            localBounds.CalcBoundingBox(),
+            Physics.Transform.Empty,
+            flags,
+            ignored);
 
-        return AnyEntitiesIntersecting(lookupUid, shape, localBounds.CalcBoundingBox(), Physics.Transform.Empty, flags, ignored);
+        _physics.ReturnPooled(polygon);
+        return result;
     }
 
     #endregion
@@ -454,8 +458,10 @@ public sealed partial class EntityLookupSystem
     {
         if (mapId == MapId.Nullspace) return false;
 
-        var shape = new Polygon(worldAABB);
-        return AnyEntitiesIntersecting(mapId, shape, Physics.Transform.Empty, flags);
+        var polygon = _physics.GetPooled(worldAABB);
+        var result = AnyEntitiesIntersecting(mapId, polygon, Physics.Transform.Empty, flags);
+        _physics.ReturnPooled(polygon);
+        return result;
     }
 
     public HashSet<EntityUid> GetEntitiesIntersecting(MapId mapId, Box2 worldAABB, LookupFlags flags = DefaultFlags)
@@ -469,8 +475,9 @@ public sealed partial class EntityLookupSystem
     {
         if (mapId == MapId.Nullspace) return;
 
-        var shape = new Polygon(worldAABB);
-        AddEntitiesIntersecting(mapId, intersecting, shape, Physics.Transform.Empty, flags);
+        var polygon = _physics.GetPooled(worldAABB);
+        AddEntitiesIntersecting(mapId, intersecting, polygon, Physics.Transform.Empty, flags);
+        _physics.ReturnPooled(polygon);
     }
 
     #endregion
@@ -480,15 +487,18 @@ public sealed partial class EntityLookupSystem
     public bool AnyEntitiesIntersecting(MapId mapId, Box2Rotated worldBounds, LookupFlags flags = DefaultFlags)
     {
         // Don't need to check contained entities as they have the same bounds as the parent.
-        var shape = new Polygon(worldBounds);
-        return AnyEntitiesIntersecting(mapId, shape, Physics.Transform.Empty, flags);
+        var polygon = _physics.GetPooled(worldBounds);
+        var result = AnyEntitiesIntersecting(mapId, polygon, Physics.Transform.Empty, flags);
+        _physics.ReturnPooled(polygon);
+        return result;
     }
 
     public HashSet<EntityUid> GetEntitiesIntersecting(MapId mapId, Box2Rotated worldBounds, LookupFlags flags = DefaultFlags)
     {
         var intersecting = new HashSet<EntityUid>();
-        var shape = new Polygon(worldBounds);
-        AddEntitiesIntersecting(mapId, intersecting, shape, Physics.Transform.Empty, flags);
+        var polygon = _physics.GetPooled(worldBounds);
+        AddEntitiesIntersecting(mapId, intersecting, polygon, Physics.Transform.Empty, flags);
+        _physics.ReturnPooled(polygon);
         return intersecting;
     }
 
@@ -703,12 +713,12 @@ public sealed partial class EntityLookupSystem
         return entities;
     }
 
-    public void GetEntitiesIntersecting(
+    public void GetEntitiesIntersecting<T>(
         MapId mapId,
-        IPhysShape shape,
+        T shape,
         Transform transform,
         HashSet<EntityUid> entities,
-        LookupFlags flags = LookupFlags.All)
+        LookupFlags flags = LookupFlags.All) where T : IPhysShape
     {
         if (mapId == MapId.Nullspace)
             return;
@@ -751,10 +761,11 @@ public sealed partial class EntityLookupSystem
             return;
 
         var localAABB = _transform.GetInvWorldMatrix(gridId).TransformBox(worldAABB);
-        var shape = new Polygon(localAABB);
+        var polygon = _physics.GetPooled(localAABB);
 
-        AddEntitiesIntersecting(gridId, intersecting, shape, localAABB, Physics.Transform.Empty, flags, lookup);
+        AddEntitiesIntersecting(gridId, intersecting, polygon, localAABB, Physics.Transform.Empty, flags, lookup);
         AddContained(intersecting, flags);
+        _physics.ReturnPooled(polygon);
     }
 
     public void GetEntitiesIntersecting(EntityUid gridId, Box2Rotated worldBounds, HashSet<EntityUid> intersecting, LookupFlags flags = DefaultFlags)
@@ -763,10 +774,11 @@ public sealed partial class EntityLookupSystem
             return;
 
         var localBounds = _transform.GetInvWorldMatrix(gridId).TransformBounds(worldBounds);
-        var shape = new Polygon(localBounds);
+        var polygon = _physics.GetPooled(localBounds);
 
-        AddEntitiesIntersecting(gridId, intersecting, shape, localBounds.CalcBoundingBox(), Physics.Transform.Empty, flags, lookup);
+        AddEntitiesIntersecting(gridId, intersecting, polygon, localBounds.CalcBoundingBox(), Physics.Transform.Empty, flags, lookup);
         AddContained(intersecting, flags);
+        _physics.ReturnPooled(polygon);
     }
 
     #endregion
@@ -832,10 +844,10 @@ public sealed partial class EntityLookupSystem
 
     #endregion
 
-    private record struct AnyEntityQueryState(
+    private record struct AnyEntityQueryState<T>(
         bool Found,
         EntityUid? Ignored,
-        IPhysShape Shape,
+        T Shape,
         Transform Transform,
         FixtureSystem Fixtures,
         EntityLookupSystem Lookup,
@@ -843,11 +855,11 @@ public sealed partial class EntityLookupSystem
         IManifoldManager Manifolds,
         EntityQuery<FixturesComponent> FixturesQuery,
         LookupFlags Flags
-    );
+    ) where T : IPhysShape;
 
-    private readonly record struct EntityQueryState(
+    private readonly record struct EntityQueryState<T>(
         HashSet<EntityUid> Intersecting,
-        IPhysShape Shape,
+        T Shape,
         Transform Transform,
         FixtureSystem Fixtures,
         EntityLookupSystem Lookup,
@@ -855,5 +867,5 @@ public sealed partial class EntityLookupSystem
         IManifoldManager Manifolds,
         EntityQuery<FixturesComponent> FixturesQuery,
         LookupFlags Flags
-    );
+    ) where T : IPhysShape;
 }

Robust.Shared/GameObjects/Systems/EntityLookupSystem.ComponentQueries.cs

@@ -67,7 +67,7 @@ public sealed partial class EntityLookupSystem
     /// <summary>
     /// Common method to determine if an entity overlaps the specified shape.
     /// </summary>
-    private bool IsIntersecting(MapId mapId, EntityUid uid, TransformComponent xform, IPhysShape shape, Transform shapeTransform, Box2 worldAABB, LookupFlags flags)
+    private bool IsIntersecting<TShape>(MapId mapId, EntityUid uid, TransformComponent xform, TShape shape, Transform shapeTransform, Box2 worldAABB, LookupFlags flags) where TShape : IPhysShape
     {
         var (entPos, entRot) = _transform.GetWorldPositionRotation(xform);
 
@@ -121,25 +121,27 @@ public sealed partial class EntityLookupSystem
         if (!_broadQuery.Resolve(lookupUid, ref lookup))
             return;
 
-        var lookupPoly = new Polygon(localAABB);
-
-        AddEntitiesIntersecting(lookupUid, intersecting, lookupPoly, localAABB, Physics.Transform.Empty, flags, query, lookup);
+        var polygon = _physics.GetPooled(localAABB);
+        AddEntitiesIntersecting(lookupUid, intersecting, polygon, localAABB, Physics.Transform.Empty, flags, query, lookup);
+        _physics.ReturnPooled(polygon);
     }
 
-    private void AddEntitiesIntersecting<T>(
+    private void AddEntitiesIntersecting<T, TShape>(
         EntityUid lookupUid,
         HashSet<Entity<T>> intersecting,
-        IPhysShape shape,
+        TShape shape,
         Box2 localAABB,
         Transform localTransform,
         LookupFlags flags,
         EntityQuery<T> query,
-        BroadphaseComponent? lookup = null) where T : IComponent
+        BroadphaseComponent? lookup = null)
+        where T : IComponent
+       where TShape : IPhysShape
     {
         if (!_broadQuery.Resolve(lookupUid, ref lookup))
             return;
 
-        var state = new QueryState<T>(
+        var state = new QueryState<T, TShape>(
             intersecting,
             shape,
             localTransform,
@@ -174,7 +176,7 @@ public sealed partial class EntityLookupSystem
 
         return;
 
-        static bool PhysicsQuery(ref QueryState<T> state, in FixtureProxy value)
+        static bool PhysicsQuery(ref QueryState<T, TShape> state, in FixtureProxy value)
         {
             if (!state.Sensors && !value.Fixture.Hard)
                 return true;
@@ -195,7 +197,7 @@ public sealed partial class EntityLookupSystem
             return true;
         }
 
-        static bool SundriesQuery(ref QueryState<T> state, in EntityUid value)
+        static bool SundriesQuery(ref QueryState<T, TShape> state, in EntityUid value)
         {
             if (!state.Query.TryGetComponent(value, out var comp))
                 return true;
@@ -250,22 +252,26 @@ public sealed partial class EntityLookupSystem
         if (!_broadQuery.Resolve(lookupUid, ref lookup))
             return false;
 
-        var shape = new Polygon(localAABB);
+        var polygon = _physics.GetPooled(localAABB);
         var (lookupPos, lookupRot) = _transform.GetWorldPositionRotation(lookupUid);
         var transform = new Transform(lookupPos, lookupRot);
+        var result = AnyComponentsIntersecting(lookupUid, polygon, localAABB, transform, flags, query, ignored, lookup);
+        _physics.ReturnPooled(polygon);
 
-        return AnyComponentsIntersecting(lookupUid, shape, localAABB, transform, flags, query, ignored, lookup);
+        return result;
     }
 
-    private bool AnyComponentsIntersecting<T>(
+    private bool AnyComponentsIntersecting<T, TShape>(
         EntityUid lookupUid,
-        IPhysShape shape,
+        TShape shape,
         Box2 localAABB,
         Transform shapeTransform,
         LookupFlags flags,
         EntityQuery<T> query,
         EntityUid? ignored = null,
-        BroadphaseComponent? lookup = null) where T : IComponent
+        BroadphaseComponent? lookup = null)
+        where T : IComponent
+       where TShape : IPhysShape
     {
         /*
          * Unfortunately this is split from the other query as we can short-circuit here, hence the code duplication.
@@ -275,7 +281,7 @@ public sealed partial class EntityLookupSystem
         if (!_broadQuery.Resolve(lookupUid, ref lookup))
             return false;
 
-        var state = new AnyQueryState<T>(false,
+        var state = new AnyQueryState<T, TShape>(false,
             ignored,
             shape,
             shapeTransform,
@@ -317,7 +323,7 @@ public sealed partial class EntityLookupSystem
 
         return state.Found;
 
-        static bool PhysicsQuery(ref AnyQueryState<T> state, in FixtureProxy value)
+        static bool PhysicsQuery(ref AnyQueryState<T, TShape> state, in FixtureProxy value)
         {
             if (value.Entity == state.Ignored)
                 return true;
@@ -342,7 +348,7 @@ public sealed partial class EntityLookupSystem
             return false;
         }
 
-        static bool SundriesQuery(ref AnyQueryState<T> state, in EntityUid value)
+        static bool SundriesQuery(ref AnyQueryState<T, TShape> state, in EntityUid value)
         {
             if (state.Ignored == value)
                 return true;
@@ -421,13 +427,14 @@ public sealed partial class EntityLookupSystem
 
     public bool AnyComponentsIntersecting(Type type, MapId mapId, Box2 worldAABB, EntityUid? ignored = null, LookupFlags flags = DefaultFlags)
     {
-        var shape = new Polygon(worldAABB);
+        var polygon = _physics.GetPooled(worldAABB);
         var transform = Physics.Transform.Empty;
-
-        return AnyComponentsIntersecting(type, mapId, shape, transform, ignored, flags);
+        var result = AnyComponentsIntersecting(type, mapId, polygon, transform, ignored, flags);
+        _physics.ReturnPooled(polygon);
+        return result;
     }
 
-    public bool AnyComponentsIntersecting(Type type, MapId mapId, IPhysShape shape, Transform shapeTransform, EntityUid? ignored = null, LookupFlags flags = DefaultFlags)
+    public bool AnyComponentsIntersecting<T>(Type type, MapId mapId, T shape, Transform shapeTransform, EntityUid? ignored = null, LookupFlags flags = DefaultFlags) where T : IPhysShape
     {
         DebugTools.Assert(typeof(IComponent).IsAssignableFrom(type));
         if (mapId == MapId.Nullspace)
@@ -489,37 +496,40 @@ public sealed partial class EntityLookupSystem
         if (mapId == MapId.Nullspace)
             return;
 
-        var shape = new Polygon(worldAABB);
+        var polygon = _physics.GetPooled(worldAABB);
         var transform = Physics.Transform.Empty;
 
-        GetEntitiesIntersecting(type, mapId, shape, transform, intersecting, flags);
+        GetEntitiesIntersecting(type, mapId, polygon, transform, intersecting, flags);
+        _physics.ReturnPooled(polygon);
     }
 
     public void GetEntitiesIntersecting<T>(MapId mapId, Box2Rotated worldBounds, HashSet<Entity<T>> entities, LookupFlags flags = DefaultFlags) where T : IComponent
     {
         if (mapId == MapId.Nullspace) return;
 
-        var shape = new Polygon(worldBounds);
+        var polygon = _physics.GetPooled(worldBounds);
         var shapeTransform = Physics.Transform.Empty;
 
-        GetEntitiesIntersecting(mapId, shape, shapeTransform, entities, flags);
+        GetEntitiesIntersecting(mapId, polygon, shapeTransform, entities, flags);
+        _physics.ReturnPooled(polygon);
     }
 
     public void GetEntitiesIntersecting<T>(MapId mapId, Box2 worldAABB, HashSet<Entity<T>> entities, LookupFlags flags = DefaultFlags) where T : IComponent
     {
         if (mapId == MapId.Nullspace) return;
 
-        var shape = new Polygon(worldAABB);
+        var polygon = _physics.GetPooled(worldAABB);
         var shapeTransform = Physics.Transform.Empty;
 
-        GetEntitiesIntersecting(mapId, shape, shapeTransform, entities, flags);
+        GetEntitiesIntersecting(mapId, polygon, shapeTransform, entities, flags);
+        _physics.ReturnPooled(polygon);
     }
 
     #endregion
 
     #region IPhysShape
 
-    public void GetEntitiesIntersecting(Type type, MapId mapId, IPhysShape shape, Transform shapeTransform, HashSet<Entity<IComponent>> intersecting, LookupFlags flags = DefaultFlags)
+    public void GetEntitiesIntersecting<T>(Type type, MapId mapId, T shape, Transform shapeTransform, HashSet<Entity<IComponent>> intersecting, LookupFlags flags = DefaultFlags) where T : IPhysShape
     {
         DebugTools.Assert(typeof(IComponent).IsAssignableFrom(type));
         if (mapId == MapId.Nullspace)
@@ -544,10 +554,10 @@ public sealed partial class EntityLookupSystem
             var query = EntityManager.GetEntityQuery(type);
 
             // Get grid entities
-            var state = new GridQueryState<IComponent>(intersecting, shape, shapeTransform, this, _physics, flags, query);
+            var state = new GridQueryState<IComponent, T>(intersecting, shape, shapeTransform, this, _physics, flags, query);
 
             _mapManager.FindGridsIntersecting(mapId, worldAABB, ref state,
-                static (EntityUid uid, MapGridComponent grid, ref GridQueryState<IComponent> state) =>
+                static (EntityUid uid, MapGridComponent grid, ref GridQueryState<IComponent, T> state) =>
                 {
                     var localTransform = state.Physics.GetRelativePhysicsTransform(state.Transform, uid);
                     var localAabb = state.Shape.ComputeAABB(localTransform, 0);
@@ -565,7 +575,9 @@ public sealed partial class EntityLookupSystem
         }
     }
 
-    public void GetEntitiesIntersecting<T>(MapId mapId, IPhysShape shape, Transform shapeTransform, HashSet<Entity<T>> entities, LookupFlags flags = DefaultFlags) where T : IComponent
+    public void GetEntitiesIntersecting<T, TShape>(MapId mapId, TShape shape, Transform shapeTransform, HashSet<Entity<T>> entities, LookupFlags flags = DefaultFlags)
+        where T : IComponent
+        where TShape : IPhysShape
     {
         if (mapId == MapId.Nullspace) return;
 
@@ -588,10 +600,10 @@ public sealed partial class EntityLookupSystem
             var query = GetEntityQuery<T>();
 
             // Get grid entities
-            var state = new GridQueryState<T>(entities, shape, shapeTransform, this, _physics, flags, query);
+            var state = new GridQueryState<T, TShape>(entities, shape, shapeTransform, this, _physics, flags, query);
 
             _mapManager.FindGridsIntersecting(mapId, worldAABB, ref state,
-                static (EntityUid uid, MapGridComponent grid, ref GridQueryState<T> state) =>
+                static (EntityUid uid, MapGridComponent grid, ref GridQueryState<T, TShape> state) =>
                 {
                     var localTransform = state.Physics.GetRelativePhysicsTransform(state.Transform, uid);
                     var localAabb = state.Shape.ComputeAABB(localTransform, 0);
@@ -679,7 +691,9 @@ public sealed partial class EntityLookupSystem
         GetEntitiesInRange(mapId, shape, transform, entities, flags);
     }
 
-    public void GetEntitiesInRange<T>(MapId mapId, IPhysShape shape, Transform transform, HashSet<Entity<T>> entities, LookupFlags flags = DefaultFlags) where T : IComponent
+    public void GetEntitiesInRange<T, TShape>(MapId mapId, TShape shape, Transform transform, HashSet<Entity<T>> entities, LookupFlags flags = DefaultFlags)
+        where T : IComponent
+        where TShape : IPhysShape
     {
         DebugTools.Assert(shape.Radius > 0, "Range must be a positive float");
 
@@ -829,20 +843,21 @@ public sealed partial class EntityLookupSystem
         }
     }
 
-    private readonly record struct GridQueryState<T>(
+    private readonly record struct GridQueryState<T, TShape>(
         HashSet<Entity<T>> Intersecting,
-        IPhysShape Shape,
+        TShape Shape,
         Transform Transform,
         EntityLookupSystem Lookup,
         SharedPhysicsSystem Physics,
         LookupFlags Flags,
         EntityQuery<T> Query
-    ) where T : IComponent;
+    ) where T : IComponent
+        where TShape : IPhysShape;
 
-    private record struct AnyQueryState<T>(
+    private record struct AnyQueryState<T, TShape>(
         bool Found,
         EntityUid? Ignored,
-        IPhysShape Shape,
+        TShape Shape,
         Transform Transform,
         FixtureSystem Fixtures,
         SharedPhysicsSystem Physics,
@@ -850,11 +865,12 @@ public sealed partial class EntityLookupSystem
         EntityQuery<T> Query,
         EntityQuery<FixturesComponent> FixturesQuery,
         LookupFlags Flags
-    ) where T : IComponent;
+    ) where T : IComponent
+     where TShape : IPhysShape;
 
-    private readonly record struct QueryState<T>(
+    private readonly record struct QueryState<T, TShape>(
         HashSet<Entity<T>> Intersecting,
-        IPhysShape Shape,
+        TShape Shape,
         Transform Transform,
         FixtureSystem Fixtures,
         SharedPhysicsSystem Physics,
@@ -863,5 +879,6 @@ public sealed partial class EntityLookupSystem
         EntityQuery<FixturesComponent> FixturesQuery,
         bool Sensors,
         bool Approximate
-    ) where T : IComponent;
+    ) where T : IComponent
+     where TShape : IPhysShape;
 }

Robust.Shared/GameObjects/Systems/SharedMapSystem.Grid.cs

@@ -312,7 +312,7 @@ public abstract partial class SharedMapSystem
 
         if (data.IsDeleted())
         {
-            if (!component.Chunks.TryGetValue(index, out var deletedChunk))
+            if (!component.Chunks.Remove(index, out var deletedChunk))
                 return;
 
             // Deleted chunks still need to raise tile-changed events.
@@ -330,11 +330,13 @@ public abstract partial class SharedMapSystem
                 }
             }
 
-            component.Chunks.Remove(index);
             return;
         }
 
         var chunk = GetOrAddChunk(uid, component, index);
+        chunk.Fixtures.Clear();
+        chunk.Fixtures.UnionWith(data.Fixtures);
+
         chunk.SuppressCollisionRegeneration = true;
         DebugTools.Assert(data.TileData.Any(x => !x.IsEmpty));
         DebugTools.Assert(data.TileData.Length == component.ChunkSize * component.ChunkSize);
@@ -355,12 +357,6 @@ public abstract partial class SharedMapSystem
         // These should never refer to the same object
         DebugTools.AssertNotEqual(chunk.Fixtures, data.Fixtures);
 
-        if (!chunk.Fixtures.SetEquals(data.Fixtures))
-        {
-            chunk.Fixtures.Clear();
-            chunk.Fixtures.UnionWith(data.Fixtures);
-        }
-
         chunk.CachedBounds = data.CachedBounds!.Value;
         chunk.SuppressCollisionRegeneration = false;
     }

Robust.Shared/GameObjects/Systems/SharedTransformSystem.Component.cs

@@ -119,7 +119,8 @@ public abstract partial class SharedTransformSystem
 
     public bool AnchorEntity(Entity<TransformComponent> entity, Entity<MapGridComponent>? grid = null)
     {
-        DebugTools.Assert(grid == null || grid.Value.Owner == entity.Comp.GridUid);
+        DebugTools.Assert(grid == null || grid.Value.Owner == entity.Comp.GridUid,
+            $"Tried to anchor entity {Name(entity)} to a grid ({grid!.Value.Owner}) different from its GridUid ({entity.Comp.GridUid})");
 
         if (grid == null)
         {
@@ -289,18 +290,26 @@ public abstract partial class SharedTransformSystem
         EntityUid uid,
         TransformComponent xform)
     {
-        // Dont set pre-init, as the map grid component might not have been added yet.
-        if (xform._gridInitialized || xform.LifeStage < ComponentLifeStage.Initializing)
+        if (xform._gridInitialized)
             return;
 
-        xform._gridInitialized = true;
-        DebugTools.Assert(xform.GridUid == null);
         if (_gridQuery.HasComponent(uid))
         {
             xform._gridUid = uid;
+            xform._gridInitialized = true;
             return;
         }
 
+        // We don't set _gridInitialized to true unless the transform (and hence entity) is already being initialized,
+        // as otherwise the current entity's grid component might just not have been added yet.
+        //
+        // We don't just return early, on the off chance that what is happening here is some convoluted entity
+        // initialization pasta, where an an entity has been attached to an un-initialized entity on an already
+        // initialized grid. In that case, the newly attached entity needs to be able to figure out the new grid id.
+        // AFAIK this shouldn't happen anymore, but might as well keep this just in case.
+        if (xform.LifeStage >= ComponentLifeStage.Initializing)
+            xform._gridInitialized = true;
+
         if (!xform._parent.IsValid())
             return;
 
@@ -726,6 +735,11 @@ public abstract partial class SharedTransformSystem
     {
         if (args.Current is TransformComponentState newState)
         {
+            // TODO Delta-states
+            // If the transform component ever gets delta states, then the client state manager needs to be updated.
+            // Currently it explicitly looks for a "TransformComponentState" when determining an entity's parent for the
+            // sake of sorting the states that need to be applied base on the transform hierarchy.
+
             var parent = EnsureEntity<TransformComponent>(newState.ParentID, uid);
             var oldAnchored = xform.Anchored;
 
@@ -899,11 +913,11 @@ public abstract partial class SharedTransformSystem
             _mapManager.TryFindGridAt(mapUid, coordinates.Position, out var targetGrid, out _))
         {
             var invWorldMatrix = GetInvWorldMatrix(targetGrid);
-            SetCoordinates(entity, new EntityCoordinates(targetGrid, Vector2.Transform(coordinates.Position, invWorldMatrix)));
+            SetCoordinates((entity.Owner, entity.Comp, MetaData(entity.Owner)), new EntityCoordinates(targetGrid, Vector2.Transform(coordinates.Position, invWorldMatrix)));
         }
         else
         {
-            SetCoordinates(entity, new EntityCoordinates(mapUid, coordinates.Position));
+            SetCoordinates((entity.Owner, entity.Comp, MetaData(entity.Owner)), new EntityCoordinates(mapUid, coordinates.Position));
         }
     }
 

Robust.Shared/GameObjects/Systems/SharedTransformSystem.cs

@@ -316,6 +316,10 @@ namespace Robust.Shared.GameObjects
         ///     Current parent entity of this entity.
         /// </summary>
         public readonly NetEntity ParentID;
+        // TODO Delta-states
+        // If the transform component ever gets delta states, then the client state manager needs to be updated.
+        // Currently it explicitly looks for a "TransformComponentState" when determining an entity's parent for the
+        // sake of sorting the states that need to be applied base on the transform hierarchy.
 
         /// <summary>
         ///     Current position offset of the entity.

Robust.Shared/GameObjects/Systems/SharedUserInterfaceSystem.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using System.Numerics;
 using System.Runtime.InteropServices;
 using JetBrains.Annotations;
 using Robust.Shared.Collections;
@@ -36,9 +37,9 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
     private ActorRangeCheckJob _rangeJob;
 
     /// <summary>
-    /// Defer closing BUIs during state handling so client doesn't spam a BUI constantly during prediction.
+    /// Defer BUIs during state handling so client doesn't spam a BUI constantly during prediction.
     /// </summary>
-    private readonly List<BoundUserInterface> _queuedCloses = new();
+    private readonly List<(BoundUserInterface Bui, bool value)> _queuedBuis = new();
 
     public override void Initialize()
     {
@@ -81,6 +82,11 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         SubscribeLocalEvent<UserInterfaceUserComponent, ComponentShutdown>(OnActorShutdown);
     }
 
+    private void AddQueued(BoundUserInterface bui, bool value)
+    {
+        _queuedBuis.Add((bui, value));
+    }
+
     /// <summary>
     /// Validates the received message, and then pass it onto systems/components
     /// </summary>
@@ -227,13 +233,7 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
 
         if (ent.Comp.ClientOpenInterfaces.TryGetValue(key, out var cBui))
         {
-            if (cBui.DeferredClose)
-                _queuedCloses.Add(cBui);
-            else
-            {
-                ent.Comp.ClientOpenInterfaces.Remove(key);
-                cBui.Dispose();
-            }
+            AddQueued(cBui, false);
         }
 
         if (ent.Comp.Actors.Count == 0)
@@ -275,24 +275,18 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         // PlayerAttachedEvent will catch some of these.
         foreach (var (key, bui) in ent.Comp.ClientOpenInterfaces)
         {
-            bui.Open();
-
-            if (ent.Comp.States.TryGetValue(key, out var state))
-            {
-                bui.UpdateState(state);
-                bui.Update();
-            }
+            AddQueued(bui, true);
         }
     }
 
-    private void OnUserInterfaceShutdown(Entity<UserInterfaceComponent> ent, ref ComponentShutdown args)
+    protected virtual void OnUserInterfaceShutdown(Entity<UserInterfaceComponent> ent, ref ComponentShutdown args)
     {
-        var actors = new List<EntityUid>();
+        var ents = new ValueList<EntityUid>();
         foreach (var (key, acts) in ent.Comp.Actors)
         {
-            actors.Clear();
-            actors.AddRange(acts);
-            foreach (var actor in actors)
+            ents.Clear();
+            ents.AddRange(acts);
+            foreach (var actor in ents)
             {
                 CloseUiInternal(ent!, key, actor);
                 DebugTools.Assert(!acts.Contains(actor));
@@ -301,7 +295,7 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
             DebugTools.Assert(!ent.Comp.Actors.ContainsKey(key));
         }
 
-        DebugTools.Assert(ent.Comp.ClientOpenInterfaces.Values.All(x => _queuedCloses.Contains(x)));
+        DebugTools.Assert(ent.Comp.ClientOpenInterfaces.Values.All(x => _queuedBuis.Contains((x, false))));
     }
 
     private void OnUserInterfaceGetState(Entity<UserInterfaceComponent> ent, ref ComponentGetState args)
@@ -463,14 +457,7 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
                 }
 
                 var bui = ent.Comp.ClientOpenInterfaces[key];
-
-                if (bui.DeferredClose)
-                    _queuedCloses.Add(bui);
-                else
-                {
-                    ent.Comp.ClientOpenInterfaces.Remove(key);
-                    bui.Dispose();
-                }
+                AddQueued(bui, false);
             }
         }
 
@@ -494,7 +481,7 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
 
                 ent.Comp.States[key] = buiState;
 
-                if (!ent.Comp.ClientOpenInterfaces.TryGetValue(key, out var cBui))
+                if (!ent.Comp.ClientOpenInterfaces.TryGetValue(key, out var cBui) || !cBui.IsOpened)
                     continue;
 
                 cBui.State = buiState;
@@ -527,9 +514,7 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         // Existing BUI just keep it.
         if (entity.Comp.ClientOpenInterfaces.TryGetValue(key, out var existing))
         {
-            if (existing.DeferredClose)
-                _queuedCloses.Remove(existing);
-
+            _queuedBuis.Remove((existing, false));
             return;
         }
 
@@ -545,10 +530,6 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         // Try-catch to try prevent error loops / bricked clients that constantly throw exceptions while applying game
         // states. E.g., stripping UI used to throw NREs in some instances while fetching the identity of unknown
         // entities.
-#if EXCEPTION_TOLERANCE
-        try
-        {
-#endif
         var type = _reflection.LooseGetType(data.ClientType);
         var boundUserInterface = (BoundUserInterface) _factory.CreateInstance(type, [entity.Owner, key]);
         entity.Comp.ClientOpenInterfaces[key] = boundUserInterface;
@@ -557,23 +538,7 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         if (!open)
             return;
 
-        boundUserInterface.Open();
-
-        if (entity.Comp.States.TryGetValue(key, out var buiState))
-        {
-            boundUserInterface.State = buiState;
-            boundUserInterface.UpdateState(buiState);
-            boundUserInterface.Update();
-        }
-#if EXCEPTION_TOLERANCE
-        }
-        catch (Exception e)
-        {
-            Log.Error(
-                $"Caught exception while attempting to create a BUI {key} with type {data.ClientType} on entity {ToPrettyString(entity.Owner)}. Exception: {e}");
-            return;
-        }
-#endif
+        AddQueued(boundUserInterface, true);
     }
 
     /// <summary>
@@ -689,6 +654,14 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         return true;
     }
 
+    /// <summary>
+    /// Opens the UI for the local client. Does nothing on server.
+    /// </summary>
+    public virtual void OpenUi(Entity<UserInterfaceComponent?> entity, Enum key, bool predicted = false)
+    {
+
+    }
+
     public void OpenUi(Entity<UserInterfaceComponent?> entity, Enum key, EntityUid? actor, bool predicted = false)
     {
         if (actor == null || !UIQuery.Resolve(entity.Owner, ref entity.Comp, false))
@@ -726,6 +699,23 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         OpenUi(entity, key, actorEnt.Value, predicted);
     }
 
+    /// <summary>
+    /// Tries to return the saved position of a user interface.
+    /// </summary>
+    public virtual bool TryGetPosition(Entity<UserInterfaceComponent?> entity, Enum key, out Vector2 position)
+    {
+        position = Vector2.Zero;
+        return false;
+    }
+
+    /// <summary>
+    /// Saves a position for the BUI.
+    /// </summary>
+    protected virtual void SavePosition(BoundUserInterface bui)
+    {
+
+    }
+
     /// <summary>
     /// Sets a BUI state and networks it to all clients.
     /// </summary>
@@ -759,8 +749,11 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         // Predict the change on client
         if (state != null && _netManager.IsClient && entity.Comp.ClientOpenInterfaces.TryGetValue(key, out var bui))
         {
-            bui.UpdateState(state);
-            bui.Update();
+            if (bui.State?.Equals(state) != true)
+            {
+                bui.UpdateState(state);
+                bui.Update();
+            }
         }
 
         DirtyField(entity, nameof(UserInterfaceComponent.States));
@@ -887,6 +880,33 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         RaiseNetworkEvent(new BoundUIWrapMessage(GetNetEntity(entity.Owner), message, key));
     }
 
+    /// <summary>
+    /// Closes the user's UIs that match the specified key.
+    /// </summary>
+    public void CloseUserUis<T>(Entity<UserInterfaceUserComponent?> actor) where T: Enum
+    {
+        if (!UserQuery.Resolve(actor.Owner, ref actor.Comp, false))
+            return;
+
+        if (actor.Comp.OpenInterfaces.Count == 0)
+            return;
+
+        var keys = new ValueList<Enum>();
+        foreach (var (uid, enums) in actor.Comp.OpenInterfaces)
+        {
+            keys.Clear();
+            keys.AddRange(enums);
+
+            foreach (var weh in keys)
+            {
+                if (weh is not T)
+                    continue;
+
+                CloseUiInternal(uid, weh, actor.Owner);
+            }
+        }
+    }
+
     /// <summary>
     /// Closes all Uis for the actor.
     /// </summary>
@@ -898,13 +918,14 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
         if (actor.Comp.OpenInterfaces.Count == 0)
             return;
 
-        var enumCopy = new ValueList<Enum>();
+        var keys = new ValueList<Enum>();
+
         foreach (var (uid, enums) in actor.Comp.OpenInterfaces)
         {
-            enumCopy.Clear();
-            enumCopy.AddRange(enums);
+            keys.Clear();
+            keys.AddRange(enums);
 
-            foreach (var key in enumCopy)
+            foreach (var key in keys)
             {
                 CloseUiInternal(uid, key, actor.Owner);
             }
@@ -1039,17 +1060,48 @@ public abstract class SharedUserInterfaceSystem : EntitySystem
     {
         if (_timing.IsFirstTimePredicted)
         {
-            foreach (var bui in _queuedCloses)
+            foreach (var (bui, open) in _queuedBuis)
             {
-                if (UIQuery.TryComp(bui.Owner, out var uiComp))
+                if (open)
                 {
-                    uiComp.ClientOpenInterfaces.Remove(bui.UiKey);
-                }
+                    bui.Open();
+#if EXCEPTION_TOLERANCE
+                    try
+                    {
+#endif
 
-                bui.Dispose();
+                    if (UIQuery.TryComp(bui.Owner, out var uiComp))
+                    {
+                        if (uiComp.States.TryGetValue(bui.UiKey, out var buiState))
+                        {
+                            bui.State = buiState;
+                            bui.UpdateState(buiState);
+                            bui.Update();
+                        }
+                    }
+#if EXCEPTION_TOLERANCE
+                    }
+                    catch (Exception e)
+                    {
+                        Log.Error(
+                            $"Caught exception while attempting to create a BUI {bui.UiKey} with type {bui.GetType()} on entity {ToPrettyString(bui.Owner)}. Exception: {e}");
+                    }
+#endif
+                }
+                // Close BUI
+                else
+                {
+                    if (UIQuery.TryComp(bui.Owner, out var uiComp))
+                    {
+                        uiComp.ClientOpenInterfaces.Remove(bui.UiKey);
+                    }
+
+                    SavePosition(bui);
+                    bui.Dispose();
+                }
             }
 
-            _queuedCloses.Clear();
+            _queuedBuis.Clear();
         }
 
         var query = AllEntityQuery<ActiveUserInterfaceComponent, UserInterfaceComponent>();

Robust.Shared/GameStates/SharedPvsOverrideSystem.cs

@@ -0,0 +1,50 @@
+using Robust.Shared.GameObjects;
+using Robust.Shared.Player;
+
+namespace Robust.Shared.GameStates;
+
+public abstract class SharedPvsOverrideSystem : EntitySystem
+{
+    /// <summary>
+    /// Forces the entity, all of its parents, and all of its children to ignore normal PVS range limitations,
+    /// causing them to always be sent to all clients.
+    /// </summary>
+    public virtual void AddGlobalOverride(EntityUid uid)
+    {
+
+    }
+
+    /// <summary>
+    /// Removes an entity from the global overrides.
+    /// </summary>
+    public virtual void RemoveGlobalOverride(EntityUid uid)
+    {
+
+    }
+
+    /// <summary>
+    /// Forces the entity, all of its parents, and all of its children to ignore normal PVS range limitations for a
+    /// specific session.
+    /// </summary>
+    public virtual void AddSessionOverride(EntityUid uid, ICommonSession session)
+    {
+
+    }
+
+    /// <summary>
+    /// Removes an entity from a session's overrides.
+    /// </summary>
+    public virtual void RemoveSessionOverride(EntityUid uid, ICommonSession session)
+    {
+
+    }
+
+    /// <summary>
+    /// Forces the entity, all of its parents, and all of its children to ignore normal PVS range limitations,
+    /// causing them to always be sent to all clients.
+    /// </summary>
+    public virtual void AddSessionOverrides(EntityUid uid, Filter filter)
+    {
+
+    }
+}

Robust.Shared/Map/Components/MapLightComponent.cs

@@ -17,7 +17,6 @@ public sealed partial class MapLightComponent : Component
     /// <summary>
     /// Ambient light. This is in linear-light, i.e. when providing a fixed colour, you must use Color.FromSrgb(Color.Black)!
     /// </summary>
-    [ViewVariables(VVAccess.ReadWrite)]
-    [DataField("ambientLightColor")]
-    public Color AmbientLightColor { get; set; } = Color.FromSrgb(Color.Black);
+    [DataField]
+    public Color AmbientLightColor = Color.FromSrgb(Color.Black);
 }

Robust.Shared/Map/IMapManager.cs

@@ -77,11 +77,11 @@ namespace Robust.Shared.Map
 
         #region MapId
 
-        public void FindGridsIntersecting(MapId mapId, IPhysShape shape, Transform transform,
-            ref List<Entity<MapGridComponent>> grids, bool approx = Approximate, bool includeMap = IncludeMap);
+        public void FindGridsIntersecting<T>(MapId mapId, T shape, Transform transform,
+            ref List<Entity<MapGridComponent>> grids, bool approx = Approximate, bool includeMap = IncludeMap) where T : IPhysShape;
 
-        public void FindGridsIntersecting(MapId mapId, IPhysShape shape, Transform transform, GridCallback callback,
-            bool approx = Approximate, bool includeMap = IncludeMap);
+        public void FindGridsIntersecting<T>(MapId mapId, T shape, Transform transform, GridCallback callback,
+            bool approx = Approximate, bool includeMap = IncludeMap) where T : IPhysShape;
 
         public void FindGridsIntersecting(MapId mapId, Box2 worldAABB, GridCallback callback, bool approx = Approximate,
             bool includeMap = IncludeMap);
@@ -107,11 +107,11 @@ namespace Robust.Shared.Map
 
         #region MapEnt
 
-        public void FindGridsIntersecting(EntityUid mapEnt, IPhysShape shape, Transform transform, GridCallback callback,
-            bool approx = Approximate, bool includeMap = IncludeMap);
+        public void FindGridsIntersecting<T>(EntityUid mapEnt, T shape, Transform transform, GridCallback callback,
+            bool approx = Approximate, bool includeMap = IncludeMap) where T : IPhysShape;
 
-        public void FindGridsIntersecting<TState>(EntityUid mapEnt, IPhysShape shape, Transform transform,
-            ref TState state, GridCallback<TState> callback, bool approx = Approximate, bool includeMap = IncludeMap);
+        public void FindGridsIntersecting<T, TState>(EntityUid mapEnt, T shape, Transform transform,
+            ref TState state, GridCallback<TState> callback, bool approx = Approximate, bool includeMap = IncludeMap) where T : IPhysShape;
 
         /// <summary>
         /// Returns true if any grids overlap the specified shapes.
@@ -119,8 +119,8 @@ namespace Robust.Shared.Map
         public void FindGridsIntersecting(EntityUid mapEnt, List<IPhysShape> shapes, Transform transform,
             ref List<Entity<MapGridComponent>> entities, bool approx = Approximate, bool includeMap = IncludeMap);
 
-        public void FindGridsIntersecting(EntityUid mapEnt, IPhysShape shape, Transform transform,
-            ref List<Entity<MapGridComponent>> grids, bool approx = Approximate, bool includeMap = IncludeMap);
+        public void FindGridsIntersecting<T>(EntityUid mapEnt, T shape, Transform transform,
+            ref List<Entity<MapGridComponent>> grids, bool approx = Approximate, bool includeMap = IncludeMap) where T : IPhysShape;
 
         public void FindGridsIntersecting(EntityUid mapEnt, Box2 worldAABB, GridCallback callback,
             bool approx = Approximate, bool includeMap = IncludeMap);

Robust.Shared/Map/MapManager.Queries.cs

@@ -8,17 +8,16 @@ using Robust.Shared.Map.Enumerators;
 using Robust.Shared.Maths;
 using Robust.Shared.Physics;
 using Robust.Shared.Physics.Collision.Shapes;
-using Robust.Shared.Physics.Shapes;
 
 namespace Robust.Shared.Map;
 
 internal partial class MapManager
 {
-    private bool IsIntersecting(
+    private bool IsIntersecting<T>(
         ChunkEnumerator enumerator,
-        IPhysShape shape,
+        T shape,
         Transform shapeTransform,
-        Entity<FixturesComponent> grid)
+        Entity<FixturesComponent> grid) where T : IPhysShape
     {
         var gridTransform = _physics.GetPhysicsTransform(grid);
 
@@ -43,14 +42,14 @@ internal partial class MapManager
 
     #region MapId
 
-    public void FindGridsIntersecting(MapId mapId, IPhysShape shape, Transform transform,
-        ref List<Entity<MapGridComponent>> grids, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
+    public void FindGridsIntersecting<T>(MapId mapId, T shape, Transform transform,
+        ref List<Entity<MapGridComponent>> grids, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap) where T : IPhysShape
     {
         if (_mapEntities.TryGetValue(mapId, out var mapEnt))
             FindGridsIntersecting(mapEnt, shape, transform, ref grids, approx, includeMap);
     }
 
-    public void FindGridsIntersecting(MapId mapId, IPhysShape shape, Transform transform, GridCallback callback, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
+    public void FindGridsIntersecting<T>(MapId mapId, T shape, Transform transform, GridCallback callback, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap) where T : IPhysShape
     {
         if (_mapEntities.TryGetValue(mapId, out var mapEnt))
             FindGridsIntersecting(mapEnt, shape, transform, callback, includeMap, approx);
@@ -100,18 +99,18 @@ internal partial class MapManager
 
     #region MapEnt
 
-    public void FindGridsIntersecting(
+    public void FindGridsIntersecting<T>(
         EntityUid mapEnt,
-        IPhysShape shape,
+        T shape,
         Transform transform,
         GridCallback callback,
         bool approx = IMapManager.Approximate,
-        bool includeMap = IMapManager.IncludeMap)
+        bool includeMap = IMapManager.IncludeMap) where T : IPhysShape
     {
         FindGridsIntersecting(mapEnt, shape, shape.ComputeAABB(transform, 0), transform, callback, approx, includeMap);
     }
 
-    private void FindGridsIntersecting(EntityUid mapEnt, IPhysShape shape, Box2 worldAABB, Transform transform, GridCallback callback, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
+    private void FindGridsIntersecting<T>(EntityUid mapEnt, T shape, Box2 worldAABB, Transform transform, GridCallback callback, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap) where T : IPhysShape
     {
         // This is here so we don't double up on code.
         var state = callback;
@@ -121,20 +120,27 @@ internal partial class MapManager
             approx: approx, includeMap: includeMap);
     }
 
-    public void FindGridsIntersecting<TState>(
+    public void FindGridsIntersecting<T, TState>(
         EntityUid mapEnt,
-        IPhysShape shape,
+        T shape,
         Transform transform,
         ref TState state,
         GridCallback<TState> callback,
         bool approx = IMapManager.Approximate,
-        bool includeMap = IMapManager.IncludeMap)
+        bool includeMap = IMapManager.IncludeMap) where T : IPhysShape
     {
         FindGridsIntersecting(mapEnt, shape, shape.ComputeAABB(transform, 0), transform, ref state, callback, approx, includeMap);
     }
 
-    private void FindGridsIntersecting<TState>(EntityUid mapEnt, IPhysShape shape, Box2 worldAABB, Transform transform,
-        ref TState state, GridCallback<TState> callback, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
+    private void FindGridsIntersecting<T, TState>(
+        EntityUid mapEnt,
+        T shape,
+        Box2 worldAABB,
+        Transform transform,
+        ref TState state,
+        GridCallback<TState> callback,
+        bool approx = IMapManager.Approximate,
+        bool includeMap = IMapManager.IncludeMap) where T : IPhysShape
     {
         if (!_gridTreeQuery.TryGetComponent(mapEnt, out var gridTree))
             return;
@@ -144,7 +150,7 @@ internal partial class MapManager
             callback(mapEnt, mapGrid, ref state);
         }
 
-        var gridState = new GridQueryState<TState>(
+        var gridState = new GridQueryState<T, TState>(
             callback,
             state,
             worldAABB,
@@ -156,8 +162,7 @@ internal partial class MapManager
             _transformSystem,
             approx);
 
-
-        gridTree.Tree.Query(ref gridState, static (ref GridQueryState<TState> state, DynamicTree.Proxy proxy) =>
+        gridTree.Tree.Query(ref gridState, static (ref GridQueryState<T, TState> state, DynamicTree.Proxy proxy) =>
         {
             // Even for approximate we'll check if any chunks roughly overlap.
             var data = state.Tree.GetUserData(proxy);
@@ -198,14 +203,14 @@ internal partial class MapManager
         }
     }
 
-    public void FindGridsIntersecting(EntityUid mapEnt, IPhysShape shape, Transform transform,
-        ref List<Entity<MapGridComponent>> grids, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
+    public void FindGridsIntersecting<T>(EntityUid mapEnt, T shape, Transform transform,
+        ref List<Entity<MapGridComponent>> grids, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap) where T : IPhysShape
     {
         FindGridsIntersecting(mapEnt, shape, shape.ComputeAABB(transform, 0), transform, ref grids, approx, includeMap);
     }
 
-    public void FindGridsIntersecting(EntityUid mapEnt, IPhysShape shape, Box2 worldAABB, Transform transform,
-        ref List<Entity<MapGridComponent>> grids, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
+    public void FindGridsIntersecting<T>(EntityUid mapEnt, T shape, Box2 worldAABB, Transform transform,
+        ref List<Entity<MapGridComponent>> grids, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap) where T : IPhysShape
     {
         var state = grids;
 
@@ -219,39 +224,48 @@ internal partial class MapManager
 
     public void FindGridsIntersecting(EntityUid mapEnt, Box2 worldAABB, GridCallback callback, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
     {
-        FindGridsIntersecting(mapEnt, new Polygon(worldAABB), worldAABB, Transform.Empty, callback, approx, includeMap);
+        var polygon = _physics.GetPooled(worldAABB);
+        FindGridsIntersecting(mapEnt, polygon, worldAABB, Transform.Empty, callback, approx, includeMap);
+        _physics.ReturnPooled(polygon);
     }
 
     public void FindGridsIntersecting<TState>(EntityUid mapEnt, Box2 worldAABB, ref TState state, GridCallback<TState> callback, bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
     {
-        FindGridsIntersecting(mapEnt, new Polygon(worldAABB), worldAABB, Transform.Empty, ref state, callback, approx, includeMap);
+        var polygon = _physics.GetPooled(worldAABB);
+        FindGridsIntersecting(mapEnt, polygon, worldAABB, Transform.Empty, ref state, callback, approx, includeMap);
+        _physics.ReturnPooled(polygon);
     }
 
     public void FindGridsIntersecting(EntityUid mapEnt, Box2 worldAABB, ref List<Entity<MapGridComponent>> grids,
         bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
     {
-        FindGridsIntersecting(mapEnt, new Polygon(worldAABB), worldAABB, Transform.Empty, ref grids, approx, includeMap);
+        var polygon = _physics.GetPooled(worldAABB);
+        FindGridsIntersecting(mapEnt, polygon, worldAABB, Transform.Empty, ref grids, approx, includeMap);
+        _physics.ReturnPooled(polygon);
     }
 
     public void FindGridsIntersecting(EntityUid mapEnt, Box2Rotated worldBounds, GridCallback callback, bool approx = IMapManager.Approximate,
         bool includeMap = IMapManager.IncludeMap)
     {
-        var shape = new Polygon(worldBounds);
-        FindGridsIntersecting(mapEnt, shape, worldBounds.CalcBoundingBox(), Transform.Empty, callback, approx, includeMap);
+        var polygon = _physics.GetPooled(worldBounds);
+        FindGridsIntersecting(mapEnt, polygon, worldBounds.CalcBoundingBox(), Transform.Empty, callback, approx, includeMap);
+        _physics.ReturnPooled(polygon);
     }
 
     public void FindGridsIntersecting<TState>(EntityUid mapEnt, Box2Rotated worldBounds, ref TState state, GridCallback<TState> callback,
         bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
     {
-        var shape = new Polygon(worldBounds);
-        FindGridsIntersecting(mapEnt, shape, worldBounds.CalcBoundingBox(), Transform.Empty, ref state, callback, approx, includeMap);
+        var polygon = _physics.GetPooled(worldBounds);
+        FindGridsIntersecting(mapEnt, polygon, worldBounds.CalcBoundingBox(), Transform.Empty, ref state, callback, approx, includeMap);
+        _physics.ReturnPooled(polygon);
     }
 
     public void FindGridsIntersecting(EntityUid mapEnt, Box2Rotated worldBounds, ref List<Entity<MapGridComponent>> grids,
         bool approx = IMapManager.Approximate, bool includeMap = IMapManager.IncludeMap)
     {
-        var shape = new Polygon(worldBounds);
-        FindGridsIntersecting(mapEnt, shape, worldBounds.CalcBoundingBox(), Transform.Empty, ref grids, approx, includeMap);
+        var polygon = _physics.GetPooled(worldBounds);
+        FindGridsIntersecting(mapEnt, polygon, worldBounds.CalcBoundingBox(), Transform.Empty, ref grids, approx, includeMap);
+        _physics.ReturnPooled(polygon);
     }
 
     #endregion
@@ -342,22 +356,11 @@ internal partial class MapManager
 
     #endregion
 
-    private readonly record struct GridQueryState(
-        GridCallback Callback,
-        Box2 WorldAABB,
-        IPhysShape Shape,
-        Transform Transform,
-        B2DynamicTree<(EntityUid Uid, FixturesComponent Fixtures, MapGridComponent Grid)> Tree,
-        SharedMapSystem MapSystem,
-        MapManager MapManager,
-        SharedTransformSystem TransformSystem,
-        bool Approximate);
-
-    private record struct GridQueryState<TState>(
+    private record struct GridQueryState<T, TState>(
         GridCallback<TState> Callback,
         TState State,
         Box2 WorldAABB,
-        IPhysShape Shape,
+        T Shape,
         Transform Transform,
         B2DynamicTree<(EntityUid Uid, FixturesComponent Fixtures, MapGridComponent Grid)> Tree,
         SharedMapSystem MapSystem,

Robust.Shared/Map/Tile.cs

@@ -1,5 +1,6 @@
 using System;
 using JetBrains.Annotations;
+using Robust.Shared.Serialization;
 using Robust.Shared.Utility;
 
 namespace Robust.Shared.Map;
@@ -16,9 +17,9 @@ public readonly struct Tile : IEquatable<Tile>, ISpanFormattable
     public readonly int TypeId;
 
     /// <summary>
-    ///     Rendering flags.
+    ///     Custom flags for additional tile-data.
     /// </summary>
-    public readonly TileRenderFlag Flags;
+    public readonly byte Flags;
 
     /// <summary>
     /// Variant of this tile to render.
@@ -39,9 +40,9 @@ public readonly struct Tile : IEquatable<Tile>, ISpanFormattable
     ///     Creates a new instance of a grid tile.
     /// </summary>
     /// <param name="typeId">Internal type ID.</param>
-    /// <param name="flags">Flags used by toolbox's rendering.</param>
+    /// <param name="flags">Custom tile flags for usage.</param>
     /// <param name="variant">The visual variant this tile is using.</param>
-    public Tile(int typeId, TileRenderFlag flags = 0, byte variant = 0)
+    public Tile(int typeId, byte flags = 0, byte variant = 0)
     {
         TypeId = typeId;
         Flags = flags;
@@ -112,9 +113,19 @@ public readonly struct Tile : IEquatable<Tile>, ISpanFormattable
             return (TypeId.GetHashCode() * 397) ^ Flags.GetHashCode() ^ Variant.GetHashCode();
         }
     }
+
+    [Pure]
+    public Tile WithVariant(byte variant)
+    {
+        return new Tile(TypeId, Flags, variant);
+    }
+
+    [Pure]
+    public Tile WithFlag(byte flag)
+    {
+        return new Tile(TypeId, flags: flag, variant: Variant);
+    }
 }
 
-public enum TileRenderFlag : byte
-{
+public sealed class TileFlagLayer {}
 
-}

Robust.Shared/Physics/Collision/CollisionManager.Overlap.cs

@@ -12,12 +12,12 @@ internal sealed partial class CollisionManager
     /// <param name="xfA">The transform for the first shape.</param>
     /// <param name="xfB">The transform for the seconds shape.</param>
     /// <returns></returns>
-    public bool TestOverlap(IPhysShape shapeA, int childIndexA, IPhysShape shapeB, int childIndexB, in Transform xfA, in Transform xfB)
+    public bool TestOverlap<T, U>(T shapeA, int indexA, U shapeB, int indexB, in Transform xfA, in Transform xfB) where T : IPhysShape where U : IPhysShape
     {
         var input = new DistanceInput();
 
-        input.ProxyA.Set(shapeA, childIndexA);
-        input.ProxyB.Set(shapeB, childIndexB);
+        input.ProxyA.Set(shapeA, indexA);
+        input.ProxyB.Set(shapeB, indexB);
         input.TransformA = xfA;
         input.TransformB = xfB;
         input.UseRadii = true;

Robust.Shared/Physics/Collision/DistanceProxy.cs

@@ -24,6 +24,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Numerics;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
@@ -56,12 +57,12 @@ internal ref struct DistanceProxy
     /// must remain in scope while the proxy is in use.
     /// </summary>
     /// <param name="shape">The shape.</param>
-    public void Set(IPhysShape shape, int index)
+    internal void Set<T>(T shape, int index) where T : IPhysShape
     {
         switch (shape.ShapeType)
         {
             case ShapeType.Circle:
-                PhysShapeCircle circle = (PhysShapeCircle) shape;
+                var circle = Unsafe.As<PhysShapeCircle>(shape);
                 Buffer._00 = circle.Position;
                 Vertices = Buffer.AsSpan[..1];
                 Radius = circle.Radius;
@@ -70,20 +71,20 @@ internal ref struct DistanceProxy
             case ShapeType.Polygon:
                 if (shape is Polygon poly)
                 {
-                    Vertices = poly.Vertices;
+                    Vertices = poly.Vertices.AsSpan()[..poly.VertexCount];
                     Radius = poly.Radius;
                 }
                 else
                 {
-                    var polyShape = (PolygonShape) shape;
-                    Vertices = polyShape.Vertices;
+                    var polyShape = Unsafe.As<PolygonShape>(shape);
+                    Vertices = polyShape.Vertices.AsSpan()[..polyShape.VertexCount];
                     Radius = polyShape.Radius;
                 }
 
                 break;
 
             case ShapeType.Chain:
-                ChainShape chain = (ChainShape) shape;
+                var chain = Unsafe.As<ChainShape>(shape);
                 Debug.Assert(0 <= index && index < chain.Vertices.Length);
 
                 Buffer._00 = chain.Vertices[index];
@@ -93,7 +94,7 @@ internal ref struct DistanceProxy
                 Radius = chain.Radius;
                 break;
             case ShapeType.Edge:
-                EdgeShape edge = (EdgeShape) shape;
+                var edge = Unsafe.As<EdgeShape>(shape);
 
                 Buffer._00 = edge.Vertex1;
                 Buffer._01 = edge.Vertex2;

Robust.Shared/Physics/Collision/IManifoldManager.cs

@@ -12,7 +12,9 @@ internal interface IManifoldManager
 
     void ReturnEdge(EdgeShape edge);
 
-    bool TestOverlap(IPhysShape shapeA, int indexA, IPhysShape shapeB, int indexB, in Transform xfA, in Transform xfB);
+    bool TestOverlap<T, U>(T shapeA, int indexA, U shapeB, int indexB, in Transform xfA, in Transform xfB)
+        where T : IPhysShape
+        where U : IPhysShape;
 
     void CollideCircles(ref Manifold manifold, PhysShapeCircle circleA, in Transform xfA,
         PhysShapeCircle circleB, in Transform xfB);

Robust.Shared/Physics/Dynamics/Contacts/Contact.cs

@@ -30,6 +30,7 @@
 using System;
 using System.Collections.Generic;
 using System.Numerics;
+using JetBrains.Annotations;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Maths;
@@ -131,6 +132,14 @@ namespace Robust.Shared.Physics.Dynamics.Contacts
         /// </summary>
         public float TangentSpeed { get; set; }
 
+        [ViewVariables]
+        public bool Deleting => (Flags & ContactFlags.Deleting) == ContactFlags.Deleting;
+
+        /// <summary>
+        /// If either fixture is hard then it's a hard contact.
+        /// </summary>
+        public bool Hard => FixtureA != null && FixtureB != null && (FixtureA.Hard && FixtureB.Hard);
+
         public void ResetRestitution()
         {
             Restitution = MathF.Max(FixtureA?.Restitution ?? 0.0f, FixtureB?.Restitution ?? 0.0f);
@@ -353,9 +362,21 @@ namespace Robust.Shared.Physics.Dynamics.Contacts
             return HashCode.Combine(EntityA, EntityB);
         }
 
+        [Pure]
+        public EntityUid OurEnt(EntityUid uid)
+        {
+            if (uid == EntityA)
+                return EntityA;
+            else if (uid == EntityB)
+                return EntityB;
+
+            throw new InvalidOperationException();
+        }
+
         /// <summary>
         /// Gets the other ent for this contact.
         /// </summary>
+        [Pure]
         public EntityUid OtherEnt(EntityUid uid)
         {
             if (uid == EntityA)
@@ -366,6 +387,18 @@ namespace Robust.Shared.Physics.Dynamics.Contacts
             throw new InvalidOperationException();
         }
 
+        [Pure, PublicAPI]
+        public (string Id, Fixture) OurFixture(EntityUid uid)
+        {
+            if (uid == EntityA)
+                return (FixtureAId, FixtureA!);
+            else if (uid == EntityB)
+                return (FixtureBId, FixtureB!);
+
+            throw new InvalidOperationException();
+        }
+
+        [Pure, PublicAPI]
         public (string Id, Fixture) OtherFixture(EntityUid uid)
         {
             if (uid == EntityA)

Robust.Shared/Physics/Shapes/Polygon.cs

@@ -16,7 +16,7 @@ internal record struct Polygon : IPhysShape
     [DataField]
     public Vector2[] Vertices;
 
-    public int VertexCount => Vertices.Length;
+    public byte VertexCount;
 
     public Vector2[] Normals;
 
@@ -42,6 +42,19 @@ internal record struct Polygon : IPhysShape
 
         Array.Copy(polyShape.Vertices, Vertices, Vertices.Length);
         Array.Copy(polyShape.Normals, Normals, Vertices.Length);
+        VertexCount = (byte) Vertices.Length;
+    }
+
+    /// <summary>
+    /// Manually constructed polygon for internal use to take advantage of pooling.
+    /// </summary>
+    internal Polygon(Vector2[] vertices, Vector2[] normals, Vector2 centroid, byte count)
+    {
+        Unsafe.SkipInit(out this);
+        Vertices = vertices;
+        Normals = normals;
+        Centroid = centroid;
+        VertexCount = count;
     }
 
     public Polygon(Box2 aabb)
@@ -61,22 +74,25 @@ internal record struct Polygon : IPhysShape
         Normals[2] = new Vector2(0.0f, 1.0f);
         Normals[3] = new Vector2(-1.0f, 0.0f);
 
+        VertexCount = 4;
         Centroid = aabb.Center;
     }
 
     public Polygon(Box2Rotated bounds)
     {
         Unsafe.SkipInit(out this);
+        Vertices = new Vector2[4];
+        Normals = new Vector2[4];
         Radius = 0f;
-        Span<Vector2> verts = stackalloc Vector2[4];
-        verts[0] = bounds.BottomLeft;
-        verts[1] = bounds.BottomRight;
-        verts[2] = bounds.TopRight;
-        verts[3] = bounds.TopLeft;
 
-        var hull = new PhysicsHull(verts, 4);
-        Set(hull);
+        Vertices[0] = bounds.BottomLeft;
+        Vertices[1] = bounds.BottomRight;
+        Vertices[2] = bounds.TopRight;
+        Vertices[3] = bounds.TopLeft;
 
+        CalculateNormals(Normals, 4);
+
+        VertexCount = 4;
         Centroid = bounds.Center;
     }
 
@@ -87,11 +103,13 @@ internal record struct Polygon : IPhysShape
 
         if (hull.Count < 3)
         {
+            VertexCount = 0;
             Vertices = [];
             Normals = [];
             return;
         }
 
+        VertexCount = (byte) vertices.Length;
         Vertices = vertices;
         Normals = new Vector2[vertices.Length];
         Set(hull);
@@ -116,9 +134,14 @@ internal record struct Polygon : IPhysShape
         }
 
         // Compute normals. Ensure the edges have non-zero length.
-        for (var i = 0; i < vertexCount; i++)
+        CalculateNormals(Normals, vertexCount);
+    }
+
+    internal void CalculateNormals(Span<Vector2> normals, int count)
+    {
+        for (var i = 0; i < count; i++)
         {
-            var next = i + 1 < vertexCount ? i + 1 : 0;
+            var next = i + 1 < count ? i + 1 : 0;
             var edge = Vertices[next] - Vertices[i];
             DebugTools.Assert(edge.LengthSquared() > float.Epsilon * float.Epsilon);
 

Robust.Shared/Physics/Systems/SharedBroadphaseSystem.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Buffers;
 using System.Collections.Generic;
 using System.Numerics;
 using System.Threading.Tasks;
@@ -8,7 +7,6 @@ using Robust.Shared.Collections;
 using Robust.Shared.Configuration;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
-using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Map.Components;
 using Robust.Shared.Maths;
@@ -413,24 +411,34 @@ namespace Robust.Shared.Physics.Systems
             }, aabb, true);
         }
 
+        [Obsolete("Use Entity<T> variant")]
         public void RegenerateContacts(EntityUid uid, PhysicsComponent body, FixturesComponent? fixtures = null, TransformComponent? xform = null)
         {
-            _physicsSystem.DestroyContacts(body);
-            if (!Resolve(uid, ref xform, ref fixtures))
+            RegenerateContacts((uid, body, fixtures, xform));
+        }
+
+        public void RegenerateContacts(Entity<PhysicsComponent?, FixturesComponent?, TransformComponent?> entity)
+        {
+            if (!Resolve(entity.Owner, ref entity.Comp1))
                 return;
 
-            if (xform.MapUid == null)
+            _physicsSystem.DestroyContacts(entity.Comp1);
+
+            if (!Resolve(entity.Owner, ref entity.Comp2 , ref entity.Comp3))
                 return;
 
-            if (!_xformQuery.TryGetComponent(xform.Broadphase?.Uid, out var broadphase))
+            if (entity.Comp3.MapUid == null)
                 return;
 
-            _physicsSystem.SetAwake((uid, body), true);
+            if (!_xformQuery.TryGetComponent(entity.Comp3.Broadphase?.Uid, out var broadphase))
+                return;
+
+            _physicsSystem.SetAwake(entity!, true);
 
             var matrix = _transform.GetWorldMatrix(broadphase);
-            foreach (var fixture in fixtures.Fixtures.Values)
+            foreach (var fixture in entity.Comp2.Fixtures.Values)
             {
-                TouchProxies(xform.MapUid.Value, matrix, fixture);
+                TouchProxies(entity.Comp3.MapUid.Value, matrix, fixture);
             }
         }
 

Robust.Shared/Physics/Systems/SharedPhysicsSystem.Components.cs

@@ -141,26 +141,26 @@ public partial class SharedPhysicsSystem
 
         if (args.Current is PhysicsLinearVelocityDeltaState linearState)
         {
-            SetLinearVelocity(uid, linearState.LinearVelocity, body: component, manager: manager);
+            SetLinearVelocity(uid, linearState.LinearVelocity, dirty: false, body: component, manager: manager);
         }
         else if (args.Current is PhysicsVelocityDeltaState velocityState)
         {
-            SetLinearVelocity(uid, velocityState.LinearVelocity, body: component, manager: manager);
-            SetAngularVelocity(uid, velocityState.AngularVelocity, body: component, manager: manager);
+            SetLinearVelocity(uid, velocityState.LinearVelocity, dirty: false, body: component, manager: manager);
+            SetAngularVelocity(uid, velocityState.AngularVelocity, dirty: false, body: component, manager: manager);
         }
         else if (args.Current is PhysicsComponentState newState)
         {
-            SetSleepingAllowed(uid, component, newState.SleepingAllowed);
-            SetFixedRotation(uid, newState.FixedRotation, body: component);
-            SetCanCollide(uid, newState.CanCollide, body: component);
+            SetSleepingAllowed(uid, component, newState.SleepingAllowed, dirty: false);
+            SetFixedRotation(uid, newState.FixedRotation, body: component, dirty: false);
+            SetCanCollide(uid, newState.CanCollide, body: component, dirty: false);
             component.BodyStatus = newState.Status;
 
-            SetLinearVelocity(uid, newState.LinearVelocity, body: component, manager: manager);
-            SetAngularVelocity(uid, newState.AngularVelocity, body: component, manager: manager);
+            SetLinearVelocity(uid, newState.LinearVelocity, dirty: false, body: component, manager: manager);
+            SetAngularVelocity(uid, newState.AngularVelocity, dirty: false, body: component, manager: manager);
             SetBodyType(uid, newState.BodyType, manager, component);
-            SetFriction(uid, component, newState.Friction);
-            SetLinearDamping(uid, component, newState.LinearDamping);
-            SetAngularDamping(uid, component, newState.AngularDamping);
+            SetFriction(uid, component, newState.Friction, dirty: false);
+            SetLinearDamping(uid, component, newState.LinearDamping, dirty: false);
+            SetAngularDamping(uid, component, newState.AngularDamping, dirty: false);
             component.Force = newState.Force;
             component.Torque = newState.Torque;
         }
@@ -276,29 +276,12 @@ public partial class SharedPhysicsSystem
     /// </summary>
     public void ResetDynamics(EntityUid uid, PhysicsComponent body, bool dirty = true)
     {
-        if (body.Torque != 0f)
-        {
-            body.Torque = 0f;
-            DirtyField(uid, body, nameof(PhysicsComponent.Torque));
-        }
-
-        if (body.AngularVelocity != 0f)
-        {
-            body.AngularVelocity = 0f;
-            DirtyField(uid, body, nameof(PhysicsComponent.AngularVelocity));
-        }
-
-        if (body.Force != Vector2.Zero)
-        {
-            body.Force = Vector2.Zero;
-            DirtyField(uid, body, nameof(PhysicsComponent.Force));
-        }
-
-        if (body.LinearVelocity != Vector2.Zero)
-        {
-            body.LinearVelocity = Vector2.Zero;
-            DirtyField(uid, body, nameof(PhysicsComponent.LinearVelocity));
-        }
+        body.Torque = 0f;
+        body.AngularVelocity = 0f;
+        body.Force = Vector2.Zero;
+        body.LinearVelocity = Vector2.Zero;
+        if (dirty)
+            DirtyFields(uid, body, null, nameof(PhysicsComponent.Torque), nameof(PhysicsComponent.AngularVelocity), nameof(PhysicsComponent.Force), nameof(PhysicsComponent.LinearVelocity));
     }
 
     public void ResetMassData(EntityUid uid, FixturesComponent? manager = null, PhysicsComponent? body = null)
@@ -403,7 +386,8 @@ public partial class SharedPhysicsSystem
             return false;
 
         body.AngularVelocity = value;
-        DirtyField(uid, body, nameof(PhysicsComponent.AngularVelocity));
+        if (dirty)
+            DirtyField(uid, body, nameof(PhysicsComponent.AngularVelocity));
 
         return true;
     }
@@ -429,7 +413,9 @@ public partial class SharedPhysicsSystem
             return false;
 
         body.LinearVelocity = velocity;
-        DirtyField(uid, body, nameof(PhysicsComponent.LinearVelocity));
+        if (dirty)
+            DirtyField(uid, body, nameof(PhysicsComponent.LinearVelocity));
+
         return true;
     }
 
@@ -439,7 +425,8 @@ public partial class SharedPhysicsSystem
             return;
 
         body.AngularDamping = value;
-        DirtyField(uid, body, nameof(PhysicsComponent.AngularDamping));
+        if (dirty)
+            DirtyField(uid, body, nameof(PhysicsComponent.AngularDamping));
     }
 
     public void SetLinearDamping(EntityUid uid, PhysicsComponent body, float value, bool dirty = true)
@@ -448,7 +435,8 @@ public partial class SharedPhysicsSystem
             return;
 
         body.LinearDamping = value;
-        DirtyField(uid, body, nameof(PhysicsComponent.LinearDamping));
+        if (dirty)
+            DirtyField(uid, body, nameof(PhysicsComponent.LinearDamping));
     }
 
     [Obsolete("Use SetAwake with EntityUid<PhysicsComponent>")]
@@ -524,32 +512,27 @@ public partial class SharedPhysicsSystem
         body.BodyType = value;
         ResetMassData(uid, manager, body);
 
+        body.Force = Vector2.Zero;
+        body.Torque = 0f;
+
         if (body.BodyType == BodyType.Static)
         {
             SetAwake((uid, body), false);
 
-            if (body.LinearVelocity != Vector2.Zero)
-            {
-                body.LinearVelocity = Vector2.Zero;
-                DirtyField(uid, body, nameof(PhysicsComponent.LinearVelocity));
-            }
+            body.LinearVelocity = Vector2.Zero;
+            body.AngularVelocity = 0f;
 
-            if (body.AngularVelocity != 0f)
-            {
-                body.AngularVelocity = 0f;
-                DirtyField(uid, body, nameof(PhysicsComponent.AngularVelocity));
-            }
+            DirtyFields(uid, body, null,
+                nameof(PhysicsComponent.LinearVelocity),
+                nameof(PhysicsComponent.AngularVelocity),
+                nameof(PhysicsComponent.Force),
+                nameof(PhysicsComponent.Torque));
         }
         // Even if it's dynamic if it can't collide then don't force it awake.
         else if (body.CanCollide)
         {
             SetAwake((uid, body), true);
-        }
-
-        if (body.Torque != 0f)
-        {
-            body.Torque = 0f;
-            DirtyField(uid, body, nameof(PhysicsComponent.Torque));
+            DirtyFields(uid, body, null, nameof(PhysicsComponent.Force), nameof(PhysicsComponent.Torque));
         }
 
         _broadphase.RegenerateContacts(uid, body, manager, xform);
@@ -567,7 +550,8 @@ public partial class SharedPhysicsSystem
             return;
 
         body.BodyStatus = status;
-        DirtyField(uid, body, nameof(PhysicsComponent.BodyStatus));
+        if (dirty)
+            DirtyField(uid, body, nameof(PhysicsComponent.BodyStatus));
     }
 
     /// <summary>
@@ -618,7 +602,10 @@ public partial class SharedPhysicsSystem
             var ev = new CollisionChangeEvent(uid, body, value);
             RaiseLocalEvent(ref ev);
         }
-        DirtyField(uid, body, nameof(PhysicsComponent.CanCollide));
+
+        if (dirty)
+            DirtyField(uid, body, nameof(PhysicsComponent.CanCollide));
+
         return value;
     }
 
@@ -628,13 +615,10 @@ public partial class SharedPhysicsSystem
             return;
 
         body.FixedRotation = value;
-        DirtyField(uid, body, nameof(PhysicsComponent.FixedRotation));
+        body.AngularVelocity = 0.0f;
 
-        if (body.AngularVelocity != 0f)
-        {
-            body.AngularVelocity = 0.0f;
-            DirtyField(uid, body, nameof(PhysicsComponent.AngularVelocity));
-        }
+        if (dirty)
+            DirtyFields(uid, body, null, nameof(PhysicsComponent.FixedRotation), nameof(PhysicsComponent.AngularVelocity));
 
         ResetMassData(uid, manager: manager, body: body);
     }
@@ -645,7 +629,8 @@ public partial class SharedPhysicsSystem
             return;
 
         body._friction = value;
-        DirtyField(uid, body, nameof(PhysicsComponent.Friction));
+        if (dirty)
+            DirtyField(uid, body, nameof(PhysicsComponent.Friction));
     }
 
     public void SetInertia(EntityUid uid, PhysicsComponent body, float value, bool dirty = true)
@@ -684,7 +669,8 @@ public partial class SharedPhysicsSystem
             SetAwake((uid, body), true);
 
         body.SleepingAllowed = value;
-        DirtyField(uid, body, nameof(PhysicsComponent.SleepingAllowed));
+        if (dirty)
+            DirtyField(uid, body, nameof(PhysicsComponent.SleepingAllowed));
     }
 
     public void SetSleepTime(PhysicsComponent body, float value)

Robust.Shared/Physics/Systems/SharedPhysicsSystem.Contacts.cs

@@ -809,10 +809,10 @@ public abstract partial class SharedPhysicsSystem
     /// Returns all of this entity's contacts.
     /// </summary>
     [Pure]
-    public ContactEnumerator GetContacts(Entity<FixturesComponent?> entity)
+    public ContactEnumerator GetContacts(Entity<FixturesComponent?> entity, bool includeDeleting = false)
     {
         _fixturesQuery.Resolve(entity.Owner, ref entity.Comp);
-        return new ContactEnumerator(entity.Comp);
+        return new ContactEnumerator(entity.Comp, includeDeleting);
     }
 }
 
@@ -823,8 +823,16 @@ public record struct ContactEnumerator
     private Dictionary<string, Fixture>.ValueCollection.Enumerator _fixtureEnumerator;
     private Dictionary<Fixture, Contact>.ValueCollection.Enumerator _contactEnumerator;
 
-    public ContactEnumerator(FixturesComponent? fixtures)
+    /// <summary>
+    /// Also include deleting contacts.
+    /// This typically includes the current contact if you're invoking this in the eventbus for an EndCollideEvent.
+    /// </summary>
+    public bool IncludeDeleting;
+
+    public ContactEnumerator(FixturesComponent? fixtures, bool includeDeleting = false)
     {
+        IncludeDeleting = includeDeleting;
+
         if (fixtures == null || fixtures.Fixtures.Count == 0)
         {
             this = Empty;
@@ -851,6 +859,10 @@ public record struct ContactEnumerator
         }
 
         contact = _contactEnumerator.Current;
+
+        if (!IncludeDeleting && contact.Deleting)
+            return MoveNext(out contact);
+
         return true;
     }
 }

Robust.Shared/Physics/Systems/SharedPhysicsSystem.Pool.cs

@@ -0,0 +1,55 @@
+using System.Buffers;
+using System.Numerics;
+using Microsoft.Extensions.ObjectPool;
+using Robust.Shared.Maths;
+using Robust.Shared.Physics.Shapes;
+
+namespace Robust.Shared.Physics.Systems;
+
+public abstract partial class SharedPhysicsSystem
+{
+    /// <summary>
+    /// Gets a polygon with pooled arrays backing it.
+    /// </summary>
+    internal Polygon GetPooled(Box2 box)
+    {
+        var vertices = ArrayPool<Vector2>.Shared.Rent(4);
+        var normals = ArrayPool<Vector2>.Shared.Rent(4);
+        var centroid = box.Center;
+
+        vertices[0] = box.BottomLeft;
+        vertices[1] = box.BottomRight;
+        vertices[2] = box.TopRight;
+        vertices[3] = box.TopLeft;
+
+        normals[0] = new Vector2(0.0f, -1.0f);
+        normals[1] = new Vector2(1.0f, 0.0f);
+        normals[2] = new Vector2(0.0f, 1.0f);
+        normals[3] = new Vector2(-1.0f, 0.0f);
+
+        return new Polygon(vertices, normals, centroid, 4);
+    }
+
+    internal Polygon GetPooled(Box2Rotated box)
+    {
+        var vertices = ArrayPool<Vector2>.Shared.Rent(4);
+        var normals = ArrayPool<Vector2>.Shared.Rent(4);
+        var centroid = box.Center;
+
+        vertices[0] = box.BottomLeft;
+        vertices[1] = box.BottomRight;
+        vertices[2] = box.TopRight;
+        vertices[3] = box.TopLeft;
+
+        var polygon = new Polygon(vertices, normals, centroid, 4);
+        polygon.CalculateNormals(normals, 4);
+
+        return polygon;
+    }
+
+    internal void ReturnPooled(Polygon polygon)
+    {
+        ArrayPool<Vector2>.Shared.Return(polygon.Vertices);
+        ArrayPool<Vector2>.Shared.Return(polygon.Normals);
+    }
+}

Robust.Shared/Physics/Systems/SharedPhysicsSystem.Queries.cs

@@ -202,27 +202,27 @@ namespace Robust.Shared.Physics.Systems
             return bodies;
         }
 
-        public HashSet<EntityUid> GetContactingEntities(EntityUid uid, PhysicsComponent? body = null, bool approximate = false)
+        public void GetContactingEntities(Entity<PhysicsComponent?> ent, HashSet<EntityUid> contacting, bool approximate = false)
         {
-            // HashSet to ensure that we only return each entity once, instead of once per colliding fixture.
-            var result = new HashSet<EntityUid>();
+            if (!Resolve(ent.Owner, ref ent.Comp))
+                return;
 
-            if (!Resolve(uid, ref body))
-                return result;
-
-            var node = body.Contacts.First;
+            var node = ent.Comp.Contacts.First;
 
             while (node != null)
             {
                 var contact = node.Value;
                 node = node.Next;
 
-                if (!approximate && !contact.IsTouching)
-                    continue;
-
-                result.Add(uid == contact.EntityA ? contact.EntityB : contact.EntityA);
+                if (approximate || contact.IsTouching)
+                    contacting.Add(ent.Owner == contact.EntityA ? contact.EntityB : contact.EntityA);
             }
+        }
 
+        public HashSet<EntityUid> GetContactingEntities(EntityUid uid, PhysicsComponent? body = null, bool approximate = false)
+        {
+            var result = new HashSet<EntityUid>();
+            GetContactingEntities((uid, body), result, approximate);
             return result;
         }
 

Robust.Shared/Physics/Systems/SharedPhysicsSystem.cs

@@ -24,7 +24,6 @@ namespace Robust.Shared.Physics.Systems
         /*
          * TODO:
 
-         * Raycasts for non-box shapes.
          * TOI Solver (continuous collision detection)
          * Poly cutting
          */
@@ -83,6 +82,13 @@ namespace Robust.Shared.Physics.Systems
 
             _physicsReg = EntityManager.ComponentFactory.GetRegistration(CompIdx.Index<PhysicsComponent>());
 
+            // TODO PHYSICS STATE
+            // Consider condensing the possible fields into just Linear velocity, angular velocity, and "Other"
+            // Or maybe even just "velocity" & "other"
+            // Then get-state doesn't have to iterate over a 10-element array.
+            // And it simplifies the DirtyField calls.
+            // Though I guess combining fixtures & physics will complicate it a bit more again.
+
             // If you update this then update the delta state + GetState + HandleState!
             EntityManager.ComponentFactory.RegisterNetworkedFields(_physicsReg,
                 nameof(PhysicsComponent.CanCollide),
@@ -320,6 +326,28 @@ namespace Robust.Shared.Physics.Systems
                     RaiseLocalEvent(ref updateMapBeforeSolve);
                 }
 
+                // TODO PHYSICS Fix Collision Mispredicts
+                // If a physics update induces a position update that brings fixtures into contact, the collision starts in the NEXT tick,
+                // as positions are updated after CollideContacts() gets called.
+                //
+                // If a player input induces a position update that brings fixtures into contact, the collision happens on the SAME tick,
+                // as inputs are handled before system updates.
+                //
+                // When applying a server's game state with new positions, the client won't know what caused the positions to update,
+                // and thus can't know whether the collision already occurred (i.e., whether its effects are already contained within the
+                // game state currently being applied), or whether it should start on the next tick and needs to predict the start of
+                // the collision.
+                //
+                // Currently the client assumes that any position updates happened due to physics steps. I.e., positions are reset, then
+                // contacts are reset via ResetContacts(), then positions are updated using the new game state. Alternatively, we could
+                // call ResetContacts() AFTER applying the server state, which would correspond to assuming that the collisions have
+                // already "started" in the state, and we don't want to re-raise the events.
+                //
+                // Currently there is no way to avoid mispredicts from happening. E.g., a simple collision-counter component will always
+                // either mispredict on physics induced position changes, or on player/input induced updates. The easiest way I can think
+                // of to fix this would be to always call `CollideContacts` again at the very end of a physics update.
+                // But that might be unnecessarily expensive for what are hopefully only infrequent mispredicts.
+
                 CollideContacts();
                 var enumerator = AllEntityQuery<PhysicsMapComponent>();
 

Robust.Shared/Properties/AssemblyInfo.cs

@@ -9,7 +9,6 @@
 [assembly: InternalsVisibleTo("Robust.UnitTesting")]
 [assembly: InternalsVisibleTo("OpenToolkit.GraphicsLibraryFramework")]
 [assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")] // Gives access to Castle(Moq)
-[assembly: InternalsVisibleTo("Content.Benchmarks")]
 [assembly: InternalsVisibleTo("Robust.Benchmarks")]
 [assembly: InternalsVisibleTo("Robust.Client.WebView")]
 [assembly: InternalsVisibleTo("Robust.Packaging")]

Robust.Shared/Prototypes/IPrototypeManager.cs

@@ -284,15 +284,21 @@ public interface IPrototypeManager
     void LoadDefaultPrototypes(Dictionary<Type, HashSet<string>>? loaded = null);
 
     /// <summary>
-    /// Syncs all inter-prototype data. Call this when operations adding new prototypes are done.
+    /// Call this when operations adding new prototypes are done.
+    /// This will handle prototype inheritance, instance creation, and update entity categories.
+    /// When loading extra prototypes, or reloading a subset of existing prototypes, you should probably use
+    /// <see cref="ReloadPrototypes"/> instead.
     /// </summary>
     void ResolveResults();
 
     /// <summary>
-    /// Invokes <see cref="PrototypesReloaded"/> with information about the modified prototypes.
-    /// When built with development tools, this will also push inheritance for reloaded prototypes/
+    /// This should be called after new or updated prototypes ahve been loaded.
+    /// This will handle prototype inheritance, instance creation, and update entity categories.
+    /// It will also invoke <see cref="PrototypesReloaded"/> and raise a <see cref="PrototypesReloadedEventArgs"/>
+    /// event with information about the modified prototypes.
     /// </summary>
-    void ReloadPrototypes(Dictionary<Type, HashSet<string>> modified,
+    void ReloadPrototypes(
+        Dictionary<Type, HashSet<string>> modified,
         Dictionary<Type, HashSet<string>>? removed = null);
 
     /// <summary>

Robust.Shared/Prototypes/PrototypeManager.YamlLoad.cs

@@ -209,10 +209,10 @@ public partial class PrototypeManager
 
         var kindData = _kinds[kind];
 
-        if (!overwrite && kindData.Results.ContainsKey(id))
+        if (!overwrite && kindData.RawResults.ContainsKey(id))
             throw new PrototypeLoadException($"Duplicate ID: '{id}' for kind '{kind}");
 
-        kindData.Results[id] = data;
+        kindData.RawResults[id] = data;
 
         if (kindData.Inheritance is { } inheritance)
         {
@@ -295,6 +295,7 @@ public partial class PrototypeManager
                 kindData.UnfrozenInstances ??= kindData.Instances.ToDictionary();
                 kindData.UnfrozenInstances.Remove(id);
                 kindData.Results.Remove(id);
+                kindData.RawResults.Remove(id);
                 modified.Add(kindData);
             }
         }

Robust.Shared/Prototypes/PrototypeManager.cs

@@ -335,98 +335,117 @@ namespace Robust.Shared.Prototypes
         }
 
         /// <inheritdoc />
-        public void ReloadPrototypes(Dictionary<Type, HashSet<string>> modified,
+        public void ReloadPrototypes(
+            Dictionary<Type, HashSet<string>> modified,
             Dictionary<Type, HashSet<string>>? removed = null)
         {
-#if TOOLS
             var prototypeTypeOrder = modified.Keys.ToList();
             prototypeTypeOrder.Sort(SortPrototypesByPriority);
 
-            var pushed = new Dictionary<Type, HashSet<string>>();
+            var byType = new Dictionary<Type, PrototypesReloadedEventArgs.PrototypeChangeSet>();
             var modifiedKinds = new HashSet<KindData>();
+            var toProcess = new HashSet<string>();
+            var processQueue = new Queue<string>();
 
             foreach (var kind in prototypeTypeOrder)
             {
+                var modifiedInstances = new Dictionary<string, IPrototype>();
                 var kindData = _kinds[kind];
-                if (!kind.IsAssignableTo(typeof(IInheritingPrototype)))
-                {
-                    foreach (var id in modified[kind])
-                    {
-                        var prototype = (IPrototype)_serializationManager.Read(kind, kindData.Results[id])!;
-                        kindData.UnfrozenInstances ??= kindData.Instances.ToDictionary();
-                        kindData.UnfrozenInstances[id] = prototype;
-                        modifiedKinds.Add(kindData);
-                    }
 
-                    continue;
-                }
+                var tree = kindData.Inheritance;
+                toProcess.Clear();
+                processQueue.Clear();
+
+                DebugTools.AssertEqual(kind.IsAssignableTo(typeof(IInheritingPrototype)), tree != null);
+                DebugTools.Assert(tree != null || kindData.RawResults == kindData.Results);
 
-                var tree = kindData.Inheritance!;
-                var processQueue = new Queue<string>();
                 foreach (var id in modified[kind])
                 {
+                    AddToQueue(id);
+                }
+
+                void AddToQueue(string id)
+                {
+                    if (!toProcess.Add(id))
+                        return;
                     processQueue.Enqueue(id);
+
+                    if (tree == null)
+                        return;
+
+                    if (!tree.TryGetChildren(id, out var children))
+                        return;
+
+                    foreach (var child in children!)
+                    {
+                        AddToQueue(child);
+                    }
                 }
 
                 while (processQueue.TryDequeue(out var id))
                 {
-                    var pushedSet = pushed.GetOrNew(kind);
-
-                    if (tree.TryGetParents(id, out var parents))
+                    DebugTools.Assert(toProcess.Contains(id));
+                    if (tree != null)
                     {
-                        var nonPushedParent = false;
-                        foreach (var parent in parents)
+                        if (tree.TryGetParents(id, out var parents))
                         {
-                            //our parent has been reloaded and has not been added to the pushedSet yet
-                            if (modified[kind].Contains(parent) && !pushedSet.Contains(parent))
+                            DebugTools.Assert(parents.Length > 0);
+                            var nonPushedParent = false;
+                            foreach (var parent in parents)
                             {
-                                //we re-queue ourselves at the end of the queue
+                                if (!toProcess.Contains(parent))
+                                    continue;
+
+                                // our parent has been modified, but has not yet been processed.
+                                // we re-queue ourselves at the end of the queue.
+                                DebugTools.Assert(processQueue.Contains(parent));
                                 processQueue.Enqueue(id);
                                 nonPushedParent = true;
                                 break;
                             }
+
+                            if (nonPushedParent)
+                                continue;
+
+                            var parentMaps = new MappingDataNode[parents.Length];
+                            for (var i = 0; i < parentMaps.Length; i++)
+                            {
+                                parentMaps[i] = kindData.Results[parents[i]];
+                            }
+
+                            kindData.Results[id] = _serializationManager.PushCompositionWithGenericNode(
+                                kind,
+                                parentMaps,
+                                kindData.RawResults[id]);
                         }
-
-                        if (nonPushedParent)
-                            continue;
-
-                        var parentMaps = new MappingDataNode[parents.Length];
-                        for (var i = 0; i < parentMaps.Length; i++)
+                        else
                         {
-                            parentMaps[i] = kindData.Results[parents[i]];
+                            kindData.Results[id] = kindData.RawResults[id];
                         }
-
-                        kindData.Results[id] = _serializationManager.PushCompositionWithGenericNode(
-                            kind,
-                            parentMaps,
-                            kindData.Results[id]);
                     }
 
+                    toProcess.Remove(id);
 
                     var prototype = TryReadPrototype(kind, id, kindData.Results[id], SerializationHookContext.DontSkipHooks);
-                    if (prototype != null)
-                    {
-                        kindData.UnfrozenInstances ??= kindData.Instances.ToDictionary();
-                        kindData.UnfrozenInstances[id] = prototype;
-                        modifiedKinds.Add(kindData);
-                    }
+                    if (prototype == null)
+                        continue;
 
-                    pushedSet.Add(id);
+                    kindData.UnfrozenInstances ??= kindData.Instances.ToDictionary();
+                    kindData.UnfrozenInstances[id] = prototype;
+                    modifiedInstances.Add(id, prototype);
                 }
+
+                if (modifiedInstances.Count == 0)
+                    continue;
+
+                byType.Add(kindData.Type, new(modifiedInstances));
+                modifiedKinds.Add(kindData);
             }
 
             Freeze(modifiedKinds);
+
             if (modifiedKinds.Any(x => x.Type == typeof(EntityPrototype) || x.Type == typeof(EntityCategoryPrototype)))
                 UpdateCategories();
-#endif
-
-            //todo paul i hate it but i am not opening that can of worms in this refactor
-            var byType = modified
-                .ToDictionary(
-                    g => g.Key,
-                    g => new PrototypesReloadedEventArgs.PrototypeChangeSet(
-                        g.Value.Where(x => _kinds[g.Key].Instances.ContainsKey(x))
-                            .ToDictionary(a => a, a => _kinds[g.Key].Instances[a])));
 
             var modifiedTypes = new HashSet<Type>(byType.Keys);
             if (removed != null)
@@ -592,11 +611,9 @@ namespace Robust.Shared.Prototypes
 
             // var sw = RStopwatch.StartNew();
 
-            var results = new Dictionary<string, InheritancePushDatum>(
-                data.Results.Select(k => new KeyValuePair<string, InheritancePushDatum>(
-                    k.Key,
-                    new InheritancePushDatum(k.Value, tree.GetParentsCount(k.Key))))
-            );
+            var results = data.RawResults.ToDictionary(
+                k => k.Key,
+                k => new InheritancePushDatum(k.Value, tree.GetParentsCount(k.Key)));
 
             using var countDown = new CountdownEvent(results.Count);
 
@@ -1015,6 +1032,8 @@ namespace Robust.Shared.Prototypes
 
             if (kind.IsAssignableTo(typeof(IInheritingPrototype)))
                 kindData.Inheritance = new MultiRootInheritanceGraph<string>();
+            else
+                kindData.Results = kindData.RawResults;
         }
 
         /// <inheritdoc />
@@ -1026,7 +1045,13 @@ namespace Robust.Shared.Prototypes
 
             public FrozenDictionary<string, IPrototype> Instances = FrozenDictionary<string, IPrototype>.Empty;
 
-            public readonly Dictionary<string, MappingDataNode> Results = new();
+            public Dictionary<string, MappingDataNode> Results = new();
+
+            /// <summary>
+            /// Variant of <see cref="Results"/> prior to inheritance pushing. If the kind does not have inheritance,
+            /// then this is just the same dictionary.
+            /// </summary>
+            public readonly Dictionary<string, MappingDataNode> RawResults = new();
 
             public readonly Type Type = kind;
             public readonly string Name = name;

Robust.Shared/Serialization/Manager/SerializationManager.Composition.cs

@@ -26,14 +26,36 @@ public partial class SerializationManager
 
     public DataNode PushComposition(Type type, DataNode[] parents, DataNode child, ISerializationContext? context = null)
     {
+        // TODO SERIALIZATION
+        // Add variant that doesn't require a parent array.
+
+        // TODO SERIALIZATION
+        // Change inheritance pushing so that it modifies the passed in child. This avoids re-creating the child
+        // multiple times when there are multiple children.
+        //
+        // I.e., change the PushCompositionDelegate signature to not have a return value, and also add an override
+        // of this method that modified the given child.
+
+        if (parents.Length == 0)
+            return child.Copy();
+
         DebugTools.Assert(parents.All(x => x.GetType() == child.GetType()));
 
+
+        // the child.Clone() statement to the beginning here, then make the delegate modify the clone.
+        // Currently pusing more than one parent requires multiple unnecessary clones.
+
         var pusher = GetOrCreatePushCompositionDelegate(type, child);
 
         var node = child;
-        for (int i = 0; i < parents.Length; i++)
+        foreach (var parent in parents)
         {
-            node = pusher(type, parents[i], node, context);
+            var newNode = pusher(type, parent, node, context);
+
+            // Currently delegate pusher should be returning a new instance, and not modifying the passed in child.
+            DebugTools.Assert(!ReferenceEquals(newNode, node));
+
+            node = newNode;
         }
 
         return node;
@@ -95,7 +117,7 @@ public partial class SerializationManager
                         Expression.Convert(parentParam, nodeType)),
                     MappingDataNode => Expression.Call(
                         instanceConst,
-                        nameof(PushInheritanceMapping),
+                        nameof(CombineMappings),
                         Type.EmptyTypes,
                         Expression.Convert(childParam, nodeType),
                         Expression.Convert(parentParam, nodeType)),
@@ -117,32 +139,26 @@ public partial class SerializationManager
         //todo implement different inheritancebehaviours for yamlfield
         // I have NFI what this comment means.
 
-        var result = new SequenceDataNode(child.Count + parent.Count);
+        var result = child.Copy();
         foreach (var entry in parent)
         {
-            result.Add(entry);
-        }
-        foreach (var entry in child)
-        {
-            result.Add(entry);
+            result.Add(entry.Copy());
         }
 
         return result;
     }
 
-    private MappingDataNode PushInheritanceMapping(MappingDataNode child, MappingDataNode parent)
+    public MappingDataNode CombineMappings(MappingDataNode child, MappingDataNode parent)
     {
         //todo implement different inheritancebehaviours for yamlfield
         // I have NFI what this comment means.
+        // I still don't know what it means, but if it's talking about the always/never push inheritance attributes,
+        // make sure it doesn't break entity serialization.
 
-        var result = new MappingDataNode(child.Count + parent.Count);
+        var result = child.Copy();
         foreach (var (k, v) in parent)
         {
-            result[k] = v;
-        }
-        foreach (var (k, v) in child)
-        {
-            result[k] = v;
+            result.TryAddCopy(k, v);
         }
 
         return result;