Update and clean up Prototype manager methods

Appearance data event

MSBuild/Robust.Engine.Version.props

@@ -1,4 +1,4 @@
 <Project>
     <!-- This file automatically reset by Tools/version.py -->
-    <PropertyGroup><Version>0.8.40</Version></PropertyGroup>
+    <PropertyGroup><Version>0.8.52</Version></PropertyGroup>
 </Project>

Robust.Analyzers/Diagnostics.cs

@@ -1,10 +1,14 @@
 using Microsoft.CodeAnalysis;
 
-namespace Robust.Generators
+namespace Robust.Analyzers;
+
+public static class Diagnostics
 {
-    public static class Diagnostics
-    {
-        public static SuppressionDescriptor MeansImplicitAssignment =>
-            new SuppressionDescriptor("RADC1000", "CS0649", "Marked as implicitly assigned.");
-    }
+    public const string IdExplicitInterface = "RA0000";
+    public const string IdSerializable = "RA0001";
+    public const string IdFriend = "RA0002";
+    public const string IdExplicitVirtual = "RA0003";
+
+    public static SuppressionDescriptor MeansImplicitAssignment =>
+        new SuppressionDescriptor("RADC1000", "CS0649", "Marked as implicitly assigned.");
 }

Robust.Analyzers/ExplicitInterfaceAnalyzer.cs

@@ -24,14 +24,14 @@ namespace Robust.Analyzers
             SyntaxKind.OverrideKeyword
         };
 
-        public const string DiagnosticId = "RA0000";
-
-        private const string Title = "No explicit interface specified";
-        private const string MessageFormat = "No explicit interface specified";
-        private const string Description = "Make sure to specify the interface in your method-declaration.";
-        private const string Category = "Usage";
-
-        [SuppressMessage("ReSharper", "RS2008")] private static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat, Category, DiagnosticSeverity.Warning, isEnabledByDefault: true, description: Description);
+        [SuppressMessage("ReSharper", "RS2008")] private static readonly DiagnosticDescriptor Rule = new(
+            Diagnostics.IdExplicitInterface,
+            "No explicit interface specified",
+            "No explicit interface specified",
+            "Usage",
+            DiagnosticSeverity.Warning,
+            isEnabledByDefault: true,
+            description: "Make sure to specify the interface in your method-declaration.");
 
         private const string RequiresExplicitImplementationAttributeMetadataName =
             "Robust.Shared.Analyzers.RequiresExplicitImplementationAttribute";

Robust.Analyzers/ExplicitVirtualAnalyzer.cs

@@ -0,0 +1,176 @@
+using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace Robust.Analyzers;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class ExplicitVirtualAnalyzer : DiagnosticAnalyzer
+{
+    internal const string Attribute = "Robust.Shared.Analyzers.VirtualAttribute";
+
+    [SuppressMessage("ReSharper", "RS2008")]
+    private static readonly DiagnosticDescriptor Rule = new(
+        Diagnostics.IdExplicitVirtual,
+        "Class must be explicitly marked as [Virtual], abstract, static or sealed",
+        "Class must be explicitly marked as [Virtual], abstract, static or sealed",
+        "Usage",
+        DiagnosticSeverity.Warning,
+        isEnabledByDefault: true,
+        description: "Class must be explicitly marked as [Virtual], abstract, static or sealed.");
+
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);
+
+    public override void Initialize(AnalysisContext context)
+    {
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+        context.EnableConcurrentExecution();
+        context.RegisterSyntaxNodeAction(AnalyzeNode, SyntaxKind.ClassDeclaration);
+    }
+
+    private static bool HasAttribute(INamedTypeSymbol namedTypeSymbol, INamedTypeSymbol attrSymbol)
+    {
+        return namedTypeSymbol.GetAttributes()
+            .Any(a => SymbolEqualityComparer.Default.Equals(a.AttributeClass, attrSymbol));
+    }
+
+    private static void AnalyzeNode(SyntaxNodeAnalysisContext context)
+    {
+        var attrSymbol = context.Compilation.GetTypeByMetadataName(Attribute);
+        var classDecl = (ClassDeclarationSyntax)context.Node;
+        var classSymbol = context.SemanticModel.GetDeclaredSymbol(classDecl);
+        if (classSymbol == null)
+            return;
+
+        if (classSymbol.IsSealed || classSymbol.IsAbstract || classSymbol.IsStatic)
+            return;
+
+        if (HasAttribute(classSymbol, attrSymbol))
+            return;
+
+        var diag = Diagnostic.Create(Rule, classDecl.Keyword.GetLocation());
+        context.ReportDiagnostic(diag);
+    }
+}
+
+// Doesn't work as I'd hoped: Roslyn doesn't provide an API for global usings and I can't get batch changes to work.
+/*
+[ExportCodeFixProvider(LanguageNames.CSharp)]
+public sealed class ExplicitVirtualCodeFixProvider : CodeFixProvider
+{
+    private const string TitleSealed = "Annotate class as sealed.";
+    private const string TitleVirtual = "Annotate class as [Virtual].";
+    private const string TitleAbstract = "Annotate class as abstract.";
+    private const string TitleStatic = "Annotate class as static.";
+
+    public override async Task RegisterCodeFixesAsync(CodeFixContext context)
+    {
+        var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken);
+
+        foreach (var diagnostic in context.Diagnostics)
+        {
+            var span = diagnostic.Location.SourceSpan;
+            var classDecl = root.FindToken(span.Start).Parent.AncestorsAndSelf().OfType<ClassDeclarationSyntax>()
+                .First();
+
+            context.RegisterCodeFix(
+                CodeAction.Create(
+                    TitleVirtual,
+                    c => FixVirtualAsync(context.Document, classDecl, c),
+                    TitleVirtual),
+                diagnostic);
+
+            context.RegisterCodeFix(
+                CodeAction.Create(
+                    TitleStatic,
+                    c => FixStaticAsync(context.Document, classDecl, c),
+                    TitleStatic),
+                diagnostic);
+
+            context.RegisterCodeFix(
+                CodeAction.Create(
+                    TitleSealed,
+                    c => FixSealedAsync(context.Document, classDecl, c),
+                    TitleSealed),
+                diagnostic);
+
+            context.RegisterCodeFix(
+                CodeAction.Create(
+                    TitleAbstract,
+                    c => FixAbstractAsync(context.Document, classDecl, c),
+                    TitleAbstract),
+                diagnostic);
+        }
+    }
+
+    private async Task<Document> FixVirtualAsync(
+        Document document,
+        ClassDeclarationSyntax classDecl,
+        CancellationToken cancellationToken)
+    {
+        var ns = "Robust.Shared.Analyzers";
+        var attrib = SyntaxFactory.Attribute(SyntaxFactory.ParseName("Virtual"));
+
+        var newClassDecl = classDecl.AddAttributeLists(
+            SyntaxFactory.AttributeList(SyntaxFactory.SeparatedList(new[] { attrib })));
+
+        var root = (CompilationUnitSyntax)await document.GetSyntaxRootAsync(cancellationToken);
+        root = root.ReplaceNode(classDecl, newClassDecl);
+
+        var options = await document.GetOptionsAsync(cancellationToken);
+
+        if (root.Usings.All(u => u.Name.ToString() != ns))
+        {
+            root = root.AddUsings(SyntaxFactory.UsingDirective(SyntaxFactory.ParseName(ns)));
+        }
+
+        return document.WithSyntaxRoot(root);
+    }
+
+    private async Task<Document> FixStaticAsync(
+        Document document,
+        ClassDeclarationSyntax classDecl,
+        CancellationToken cancellationToken)
+    {
+        var newClassDecl = classDecl.AddModifiers(SyntaxFactory.Token(SyntaxKind.StaticKeyword));
+
+        var root = (CompilationUnitSyntax)await document.GetSyntaxRootAsync(cancellationToken);
+        root = root.ReplaceNode(classDecl, newClassDecl);
+
+        return document.WithSyntaxRoot(root);
+    }
+
+    private async Task<Document> FixAbstractAsync(
+        Document document,
+        ClassDeclarationSyntax classDecl,
+        CancellationToken cancellationToken)
+    {
+        var newClassDecl = classDecl.AddModifiers(SyntaxFactory.Token(SyntaxKind.AbstractKeyword));
+
+        var root = (CompilationUnitSyntax)await document.GetSyntaxRootAsync(cancellationToken);
+        root = root.ReplaceNode(classDecl, newClassDecl);
+
+        return document.WithSyntaxRoot(root);
+    }
+
+    private async Task<Document> FixSealedAsync(
+        Document document,
+        ClassDeclarationSyntax classDecl,
+        CancellationToken cancellationToken)
+    {
+        var newClassDecl = classDecl.AddModifiers(SyntaxFactory.Token(SyntaxKind.SealedKeyword));
+
+        var root = (CompilationUnitSyntax)await document.GetSyntaxRootAsync(cancellationToken);
+        root = root.ReplaceNode(classDecl, newClassDecl);
+
+        return document.WithSyntaxRoot(root);
+    }
+
+    public override FixAllProvider GetFixAllProvider() => WellKnownFixAllProviders.BatchFixer;
+    public override ImmutableArray<string> FixableDiagnosticIds => ImmutableArray.Create(Diagnostics.IdExplicitVirtual);
+}
+*/

Robust.Analyzers/FriendAnalyzer.cs

@@ -14,15 +14,15 @@ namespace Robust.Analyzers
     {
         const string FriendAttribute = "Robust.Shared.Analyzers.FriendAttribute";
 
-        public const string DiagnosticId = "RA0002";
-
-        private const string Title = "Tried to access friend-only member";
-        private const string MessageFormat = "Tried to access member \"{0}\" in class \"{1}\" which can only be accessed by friend classes";
-        private const string Description = "Make sure to specify the accessing class in the friends attribute.";
-        private const string Category = "Usage";
-
         [SuppressMessage("ReSharper", "RS2008")]
-        private static readonly DiagnosticDescriptor Rule = new (DiagnosticId, Title, MessageFormat, Category, DiagnosticSeverity.Error, true, Description);
+        private static readonly DiagnosticDescriptor Rule = new (
+            Diagnostics.IdFriend,
+            "Tried to access friend-only member",
+            "Tried to access member \"{0}\" in class \"{1}\" which can only be accessed by friend classes",
+            "Usage",
+            DiagnosticSeverity.Error,
+            true,
+            "Make sure to specify the accessing class in the friends attribute.");
 
         public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);
 

Robust.Analyzers/MeansImplicitAssigmentSuppressor.cs

@@ -1,9 +1,7 @@
-using System;
 using System.Collections.Immutable;
 using System.Linq;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
-using Robust.Generators;
 
 namespace Robust.Analyzers
 {

Robust.Analyzers/Robust.Analyzers.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <LangVersion>9</LangVersion>
+    <LangVersion>10</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>

Robust.Analyzers/SerializableAnalyzer.cs

@@ -17,19 +17,21 @@ namespace Robust.Analyzers
     public class SerializableAnalyzer : DiagnosticAnalyzer
     {
         // Metadata of the analyzer
-        public const string DiagnosticId = "RA0001";
 
         // You could use LocalizedString but it's a little more complicated for this sample
-        private const string Title = "Class not marked as (Net)Serializable";
-        private const string MessageFormat = "Class not marked as (Net)Serializable";
-        private const string Description = "The class should be marked as (Net)Serializable.";
-        private const string Category = "Usage";
 
         private const string RequiresSerializableAttributeMetadataName = "Robust.Shared.Analyzers.RequiresSerializableAttribute";
         private const string SerializableAttributeMetadataName = "System.SerializableAttribute";
         private const string NetSerializableAttributeMetadataName = "Robust.Shared.Serialization.NetSerializableAttribute";
 
-        [SuppressMessage("ReSharper", "RS2008")] private static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat, Category, DiagnosticSeverity.Warning, isEnabledByDefault: true, description: Description);
+        [SuppressMessage("ReSharper", "RS2008")] private static readonly DiagnosticDescriptor Rule = new(
+            Diagnostics.IdSerializable,
+            "Class not marked as (Net)Serializable",
+            "Class not marked as (Net)Serializable",
+            "Usage",
+            DiagnosticSeverity.Warning,
+            isEnabledByDefault: true,
+            description: "The class should be marked as (Net)Serializable.");
 
         public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);
 
@@ -139,7 +141,8 @@ namespace Robust.Analyzers
             return document.WithSyntaxRoot(root);
         }
 
-        public sealed override ImmutableArray<string> FixableDiagnosticIds => ImmutableArray.Create(SerializableAnalyzer.DiagnosticId);
+        public sealed override ImmutableArray<string> FixableDiagnosticIds
+            => ImmutableArray.Create(Diagnostics.IdSerializable);
 
         public override FixAllProvider GetFixAllProvider()
         {

Robust.Benchmarks/NumericsHelpers/AddBenchmark.cs

@@ -1,7 +1,9 @@
 using BenchmarkDotNet.Attributes;
+using Robust.Shared.Analyzers;
 
 namespace Robust.Benchmarks.NumericsHelpers
 {
+    [Virtual]
     public class AddBenchmark
     {
         [Params(32, 128)]

Robust.Benchmarks/Program.cs

@@ -4,7 +4,7 @@ using System;
 
 namespace Robust.Benchmarks
 {
-    internal class Program
+    internal static class Program
     {
         // --allCategories=ctg1,ctg2
         // --anyCategories=ctg1,ctg2

Robust.Benchmarks/Serialization/BenchmarkIntSerializer.cs

@@ -9,7 +9,7 @@ using Robust.Shared.Serialization.TypeSerializers.Interfaces;
 
 namespace Robust.Benchmarks.Serialization
 {
-    public class BenchmarkIntSerializer : ITypeSerializer<int, ValueDataNode>
+    public sealed class BenchmarkIntSerializer : ITypeSerializer<int, ValueDataNode>
     {
         public ValidationNode Validate(ISerializationManager serializationManager, ValueDataNode node,
             IDependencyCollection dependencies, ISerializationContext? context = null)

Robust.Benchmarks/Serialization/Copy/SerializationCopyBenchmark.cs

@@ -2,6 +2,7 @@
 using System.Linq;
 using BenchmarkDotNet.Attributes;
 using Robust.Benchmarks.Serialization.Definitions;
+using Robust.Shared.Analyzers;
 using Robust.Shared.Serialization.Manager;
 using Robust.Shared.Serialization.Markdown;
 using Robust.Shared.Serialization.Markdown.Mapping;
@@ -13,6 +14,7 @@ using YamlDotNet.RepresentationModel;
 namespace Robust.Benchmarks.Serialization.Copy
 {
     [MemoryDiagnoser]
+    [Virtual]
     public class SerializationCopyBenchmark : SerializationBenchmark
     {
         public SerializationCopyBenchmark()

Robust.Benchmarks/Serialization/Definitions/BenchmarkFlags.cs

@@ -3,7 +3,7 @@ using Robust.Shared.Serialization;
 
 namespace Robust.Benchmarks.Serialization.Definitions
 {
-    public class BenchmarkFlags
+    public sealed class BenchmarkFlags
     {
         public const int Zero = 1 << 0;
         public const int ThirtyOne = 1 << 31;

Robust.Benchmarks/Serialization/Definitions/DataDefinitionWithString.cs

@@ -1,8 +1,10 @@
-using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.Analyzers;
+using Robust.Shared.Serialization.Manager.Attributes;
 
 namespace Robust.Benchmarks.Serialization.Definitions
 {
     [DataDefinition]
+    [Virtual]
     public class DataDefinitionWithString
     {
         [DataField("string")]

Robust.Benchmarks/Serialization/Definitions/SeedDataDefinition.cs

@@ -11,7 +11,7 @@ namespace Robust.Benchmarks.Serialization.Definitions
     ///     Taken from content.
     /// </summary>
     [Prototype("seed")]
-    public class SeedDataDefinition : IPrototype
+    public sealed class SeedDataDefinition : IPrototype
     {
         public const string Prototype = @"
 - type: seed

Robust.Benchmarks/Serialization/Initialize/SerializationInitializeBenchmark.cs

@@ -1,9 +1,11 @@
 using BenchmarkDotNet.Attributes;
+using Robust.Shared.Analyzers;
 using Robust.Shared.Serialization.Manager;
 
 namespace Robust.Benchmarks.Serialization.Initialize
 {
     [MemoryDiagnoser]
+    [Virtual]
     public class SerializationInitializeBenchmark : SerializationBenchmark
     {
         [IterationCleanup]

Robust.Benchmarks/Serialization/Read/SerializationReadBenchmark.cs

@@ -1,6 +1,7 @@
 using System.IO;
 using BenchmarkDotNet.Attributes;
 using Robust.Benchmarks.Serialization.Definitions;
+using Robust.Shared.Analyzers;
 using Robust.Shared.Serialization.Manager.Result;
 using Robust.Shared.Serialization.Markdown;
 using Robust.Shared.Serialization.Markdown.Mapping;
@@ -12,6 +13,7 @@ using YamlDotNet.RepresentationModel;
 namespace Robust.Benchmarks.Serialization.Read
 {
     [MemoryDiagnoser]
+    [Virtual]
     public class SerializationReadBenchmark : SerializationBenchmark
     {
         public SerializationReadBenchmark()

Robust.Benchmarks/Serialization/SerializationArrayBenchmark.cs

@@ -1,5 +1,6 @@
 using BenchmarkDotNet.Attributes;
 using Robust.Benchmarks.Serialization.Definitions;
+using Robust.Shared.Analyzers;
 using Robust.Shared.Serialization.Markdown.Mapping;
 using Robust.Shared.Serialization.Markdown.Sequence;
 using Robust.Shared.Serialization.Markdown.Value;
@@ -7,6 +8,7 @@ using Robust.Shared.Serialization.Markdown.Value;
 namespace Robust.Benchmarks.Serialization
 {
     [MemoryDiagnoser]
+    [Virtual]
     public class SerializationArrayBenchmark : SerializationBenchmark
     {
         public SerializationArrayBenchmark()

Robust.Benchmarks/Serialization/Write/SerializationWriteBenchmark.cs

@@ -2,6 +2,7 @@
 using System.IO;
 using BenchmarkDotNet.Attributes;
 using Robust.Benchmarks.Serialization.Definitions;
+using Robust.Shared.Analyzers;
 using Robust.Shared.Serialization.Manager;
 using Robust.Shared.Serialization.Markdown;
 using Robust.Shared.Serialization.Markdown.Mapping;
@@ -13,6 +14,7 @@ using YamlDotNet.RepresentationModel;
 namespace Robust.Benchmarks.Serialization.Write
 {
     [MemoryDiagnoser]
+    [Virtual]
     public class SerializationWriteBenchmark : SerializationBenchmark
     {
         public SerializationWriteBenchmark()

Robust.Client/Animations/AnimationTrackControlProperty.cs

@@ -3,7 +3,7 @@ using Robust.Shared.Animations;
 
 namespace Robust.Client.Animations
 {
-    public class AnimationTrackControlProperty : AnimationTrackProperty
+    public sealed class AnimationTrackControlProperty : AnimationTrackProperty
     {
         public string? Property { get; set; }
 

Robust.Client/Audio/Midi/MidiManager.cs

@@ -58,7 +58,7 @@ namespace Robust.Client.Audio.Midi
         void Shutdown();
     }
 
-    internal class MidiManager : IMidiManager
+    internal sealed class MidiManager : IMidiManager
     {
         [Dependency] private readonly IEyeManager _eyeManager = default!;
         [Dependency] private readonly IResourceManagerInternal _resourceManager = default!;
@@ -392,7 +392,7 @@ namespace Robust.Client.Audio.Midi
         /// <summary>
         ///     This class is used to load soundfonts.
         /// </summary>
-        private class ResourceLoaderCallbacks : SoundFontLoaderCallbacks
+        private sealed class ResourceLoaderCallbacks : SoundFontLoaderCallbacks
         {
             private readonly Dictionary<int, Stream> _openStreams = new();
             private int _nextStreamId = 1;

Robust.Client/Audio/Midi/MidiRenderer.cs

@@ -180,7 +180,7 @@ namespace Robust.Client.Audio.Midi
         internal void InternalDispose();
     }
 
-    internal class MidiRenderer : IMidiRenderer
+    internal sealed class MidiRenderer : IMidiRenderer
     {
         [Dependency] private readonly IClydeAudio _clydeAudio = default!;
         [Dependency] private readonly ITaskManager _taskManager = default!;

Robust.Client/BaseClient.cs

@@ -20,7 +20,7 @@ using Robust.Shared.Utility;
 namespace Robust.Client
 {
     /// <inheritdoc />
-    public class BaseClient : IBaseClient
+    public sealed class BaseClient : IBaseClient
     {
         [Dependency] private readonly IClientNetManager _net = default!;
         [Dependency] private readonly IPlayerManager _playMan = default!;
@@ -291,7 +291,7 @@ namespace Robust.Client
     /// <summary>
     ///     Event arguments for when something changed with the player.
     /// </summary>
-    public class PlayerEventArgs : EventArgs
+    public sealed class PlayerEventArgs : EventArgs
     {
         /// <summary>
         ///     The session that triggered the event.
@@ -310,7 +310,7 @@ namespace Robust.Client
     /// <summary>
     ///     Event arguments for when the RunLevel has changed in the BaseClient.
     /// </summary>
-    public class RunLevelChangedEventArgs : EventArgs
+    public sealed class RunLevelChangedEventArgs : EventArgs
     {
         /// <summary>
         ///     RunLevel that the BaseClient switched from.
@@ -335,7 +335,7 @@ namespace Robust.Client
     /// <summary>
     ///     Info about the server and player that is sent to the client while connecting.
     /// </summary>
-    public class ServerInfo
+    public sealed class ServerInfo
     {
         public ServerInfo(string serverName)
         {

Robust.Client/ClientIoC.cs

@@ -43,9 +43,9 @@ namespace Robust.Client
             IoCManager.Register<IGameTiming, ClientGameTiming>();
             IoCManager.Register<IClientGameTiming, ClientGameTiming>();
             IoCManager.Register<IPrototypeManager, ClientPrototypeManager>();
-            IoCManager.Register<IMapManager, ClientMapManager>();
-            IoCManager.Register<IMapManagerInternal, ClientMapManager>();
-            IoCManager.Register<IClientMapManager, ClientMapManager>();
+            IoCManager.Register<IMapManager, NetworkedMapManager>();
+            IoCManager.Register<IMapManagerInternal, NetworkedMapManager>();
+            IoCManager.Register<INetworkedMapManager, NetworkedMapManager>();
             IoCManager.Register<IEntityManager, ClientEntityManager>();
             IoCManager.Register<IEntityLookup, EntityLookup>();
             IoCManager.Register<IReflectionManager, ClientReflectionManager>();

Robust.Client/Console/ClientConGroupController.cs

@@ -2,7 +2,7 @@
 
 namespace Robust.Client.Console
 {
-    public class ClientConGroupController : IClientConGroupController
+    public sealed class ClientConGroupController : IClientConGroupController
     {
         private IClientConGroupImplementation? _implementation;
         public event Action? ConGroupUpdated;

Robust.Client/Console/ClientConsoleHost.cs

@@ -14,7 +14,7 @@ using Robust.Shared.Utility;
 
 namespace Robust.Client.Console
 {
-    public class AddStringArgs : EventArgs
+    public sealed class AddStringArgs : EventArgs
     {
         public string Text { get; }
 
@@ -30,7 +30,7 @@ namespace Robust.Client.Console
         }
     }
 
-    public class AddFormattedMessageArgs : EventArgs
+    public sealed class AddFormattedMessageArgs : EventArgs
     {
         public readonly FormattedMessage Message;
 
@@ -41,7 +41,7 @@ namespace Robust.Client.Console
     }
 
     /// <inheritdoc cref="IClientConsoleHost" />
-    internal class ClientConsoleHost : ConsoleHost, IClientConsoleHost
+    internal sealed class ClientConsoleHost : ConsoleHost, IClientConsoleHost
     {
         [Dependency] private readonly IClientConGroupController _conGroup = default!;
 
@@ -209,7 +209,7 @@ namespace Robust.Client.Console
     /// These dummies are made purely so list and help can list server-side commands.
     /// </summary>
     [Reflect(false)]
-    internal class ServerDummyCommand : IConsoleCommand
+    internal sealed class ServerDummyCommand : IConsoleCommand
     {
         internal ServerDummyCommand(string command, string help, string description)
         {

Robust.Client/Console/Commands/ConfigurationCommands.cs

@@ -59,7 +59,7 @@ namespace Robust.Client.Console.Commands
     }
 
     [UsedImplicitly]
-    public class SaveConfig : IConsoleCommand
+    public sealed class SaveConfig : IConsoleCommand
     {
         public string Command => "saveconfig";
         public string Description => "Saves the client configuration to the config file";

Robust.Client/Console/Commands/ConsoleCommands.cs

@@ -6,7 +6,7 @@ using Robust.Shared.Console;
 
 namespace Robust.Client.Console.Commands
 {
-    class ClearCommand : IConsoleCommand
+    sealed class ClearCommand : IConsoleCommand
     {
         public string Command => "cls";
         public string Help => "Clears the debug console of all messages.";
@@ -18,7 +18,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    class FillCommand : IConsoleCommand
+    sealed class FillCommand : IConsoleCommand
     {
         public string Command => "fill";
         public string Help => "Fills the console with some nonsense for debugging.";

Robust.Client/Console/Commands/Debug.cs

@@ -30,7 +30,7 @@ using static Robust.Client.UserInterface.Controls.BoxContainer;
 
 namespace Robust.Client.Console.Commands
 {
-    internal class DumpEntitiesCommand : IConsoleCommand
+    internal sealed class DumpEntitiesCommand : IConsoleCommand
     {
         public string Command => "dumpentities";
         public string Help => "Dump entity list";
@@ -47,7 +47,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class GetComponentRegistrationCommand : IConsoleCommand
+    internal sealed class GetComponentRegistrationCommand : IConsoleCommand
     {
         public string Command => "getcomponentregistration";
         public string Help => "Usage: getcomponentregistration <componentName>";
@@ -93,7 +93,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ToggleMonitorCommand : IConsoleCommand
+    internal sealed class ToggleMonitorCommand : IConsoleCommand
     {
         public string Command => "monitor";
 
@@ -148,7 +148,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ExceptionCommand : IConsoleCommand
+    internal sealed class ExceptionCommand : IConsoleCommand
     {
         public string Command => "fuck";
         public string Help => "Throws an exception";
@@ -160,7 +160,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ShowPositionsCommand : IConsoleCommand
+    internal sealed class ShowPositionsCommand : IConsoleCommand
     {
         public string Command => "showpos";
         public string Help => "";
@@ -173,7 +173,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ShowRayCommand : IConsoleCommand
+    internal sealed class ShowRayCommand : IConsoleCommand
     {
         public string Command => "showrays";
         public string Help => "Usage: showrays <raylifetime>";
@@ -200,7 +200,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class DisconnectCommand : IConsoleCommand
+    internal sealed class DisconnectCommand : IConsoleCommand
     {
         public string Command => "disconnect";
         public string Help => "";
@@ -212,7 +212,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class EntityInfoCommand : IConsoleCommand
+    internal sealed class EntityInfoCommand : IConsoleCommand
     {
         public string Command => "entfo";
 
@@ -264,7 +264,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class SnapGridGetCell : IConsoleCommand
+    internal sealed class SnapGridGetCell : IConsoleCommand
     {
         public string Command => "sggcell";
         public string Help => "sggcell <gridID> <vector2i>\nThat vector2i param is in the form x<int>,y<int>.";
@@ -313,7 +313,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class SetPlayerName : IConsoleCommand
+    internal sealed class SetPlayerName : IConsoleCommand
     {
         public string Command => "overrideplayername";
         public string Description => "Changes the name used when attempting to connect to the server.";
@@ -333,7 +333,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class LoadResource : IConsoleCommand
+    internal sealed class LoadResource : IConsoleCommand
     {
         public string Command => "ldrsc";
         public string Description => "Pre-caches a resource.";
@@ -370,7 +370,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ReloadResource : IConsoleCommand
+    internal sealed class ReloadResource : IConsoleCommand
     {
         public string Command => "rldrsc";
         public string Description => "Reloads a resource.";
@@ -404,7 +404,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class GridTileCount : IConsoleCommand
+    internal sealed class GridTileCount : IConsoleCommand
     {
         public string Command => "gridtc";
         public string Description => "Gets the tile count of a grid";
@@ -438,7 +438,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class GuiDumpCommand : IConsoleCommand
+    internal sealed class GuiDumpCommand : IConsoleCommand
     {
         public string Command => "guidump";
         public string Description => "Dump GUI tree to /guidump.txt in user data.";
@@ -512,7 +512,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class UITestCommand : IConsoleCommand
+    internal sealed class UITestCommand : IConsoleCommand
     {
         public string Command => "uitest";
         public string Description => "Open a dummy UI testing window";
@@ -644,7 +644,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class SetClipboardCommand : IConsoleCommand
+    internal sealed class SetClipboardCommand : IConsoleCommand
     {
         public string Command => "setclipboard";
         public string Description => "Sets the system clipboard";
@@ -657,7 +657,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class GetClipboardCommand : IConsoleCommand
+    internal sealed class GetClipboardCommand : IConsoleCommand
     {
         public string Command => "getclipboard";
         public string Description => "Gets the system clipboard";
@@ -670,7 +670,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ToggleLight : IConsoleCommand
+    internal sealed class ToggleLight : IConsoleCommand
     {
         public string Command => "togglelight";
         public string Description => "Toggles light rendering.";
@@ -684,7 +684,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ToggleFOV : IConsoleCommand
+    internal sealed class ToggleFOV : IConsoleCommand
     {
         public string Command => "togglefov";
         public string Description => "Toggles fov for client.";
@@ -698,7 +698,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ToggleHardFOV : IConsoleCommand
+    internal sealed class ToggleHardFOV : IConsoleCommand
     {
         public string Command => "togglehardfov";
         public string Description => "Toggles hard fov for client (for debugging space-station-14#2353).";
@@ -712,7 +712,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ToggleShadows : IConsoleCommand
+    internal sealed class ToggleShadows : IConsoleCommand
     {
         public string Command => "toggleshadows";
         public string Description => "Toggles shadow rendering.";
@@ -725,7 +725,7 @@ namespace Robust.Client.Console.Commands
                 mgr.DrawShadows = !mgr.DrawShadows;
         }
     }
-    internal class ToggleLightBuf : IConsoleCommand
+    internal sealed class ToggleLightBuf : IConsoleCommand
     {
         public string Command => "togglelightbuf";
         public string Description => "Toggles lighting rendering. This includes shadows but not FOV.";
@@ -739,7 +739,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class GcCommand : IConsoleCommand
+    internal sealed class GcCommand : IConsoleCommand
     {
         public string Command => "gc";
         public string Description => "Run the GC.";
@@ -761,7 +761,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class GcFullCommand : IConsoleCommand
+    internal sealed class GcFullCommand : IConsoleCommand
     {
         public string Command => "gcf";
         public string Description => "Run the GC, fully, compacting LOH and everything.";
@@ -774,7 +774,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class GcModeCommand : IConsoleCommand
+    internal sealed class GcModeCommand : IConsoleCommand
     {
 
         public string Command => "gc_mode";
@@ -816,7 +816,7 @@ namespace Robust.Client.Console.Commands
 
     }
 
-    internal class SerializeStatsCommand : IConsoleCommand
+    internal sealed class SerializeStatsCommand : IConsoleCommand
     {
 
         public string Command => "szr_stats";
@@ -836,7 +836,7 @@ namespace Robust.Client.Console.Commands
 
     }
 
-    internal class ChunkInfoCommand : IConsoleCommand
+    internal sealed class ChunkInfoCommand : IConsoleCommand
     {
         public string Command => "chunkinfo";
         public string Description => "Gets info about a chunk under your mouse cursor.";
@@ -865,7 +865,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class ReloadShadersCommand : IConsoleCommand
+    internal sealed class ReloadShadersCommand : IConsoleCommand
     {
 
         public string Command => "rldshader";
@@ -1036,7 +1036,7 @@ namespace Robust.Client.Console.Commands
 
     }
 
-    internal class ClydeDebugLayerCommand : IConsoleCommand
+    internal sealed class ClydeDebugLayerCommand : IConsoleCommand
     {
         public string Command => "cldbglyr";
         public string Description => "Toggle fov and light debug layers";
@@ -1061,7 +1061,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    internal class GetKeyInfoCommand : IConsoleCommand
+    internal sealed class GetKeyInfoCommand : IConsoleCommand
     {
         public string Command => "keyinfo";
         public string Description => "Keys key info for a key";

Robust.Client/Console/Commands/GridChunkBBCommand.cs

@@ -4,7 +4,7 @@ using Robust.Shared.GameObjects;
 
 namespace Robust.Client.Console.Commands
 {
-    public class GridChunkBBCommand : IConsoleCommand
+    public sealed class GridChunkBBCommand : IConsoleCommand
     {
         public string Command => "showchunkbb";
         public string Description => "Displays chunk bounds for the purposes of rendering";

Robust.Client/Console/Commands/HelpCommands.cs

@@ -5,7 +5,7 @@ using Robust.Shared.Network;
 
 namespace Robust.Client.Console.Commands
 {
-    class HelpCommand : IConsoleCommand
+    sealed class HelpCommand : IConsoleCommand
     {
         public string Command => "help";
         public string Help => "When no arguments are provided, displays a generic help text. When an argument is passed, display the help text for the command with that name.";
@@ -44,7 +44,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    class ListCommand : IConsoleCommand
+    sealed class ListCommand : IConsoleCommand
     {
         public string Command => "list";
         public string Help => "Usage: list [filter]\n" +

Robust.Client/Console/Commands/LogCommands.cs

@@ -4,7 +4,7 @@ using Robust.Shared.Console;
 
 namespace Robust.Client.Console.Commands
 {
-    class LogSetLevelCommand : IConsoleCommand
+    sealed class LogSetLevelCommand : IConsoleCommand
     {
         public string Command => "loglevel";
         public string Description => "Changes the log level for a provided sawmill.";
@@ -40,7 +40,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    class TestLog : IConsoleCommand
+    sealed class TestLog : IConsoleCommand
     {
         public string Command => "testlog";
         public string Description => "Writes a test log to a sawmill.";

Robust.Client/Console/Commands/QuitCommand.cs

@@ -4,7 +4,7 @@ using Robust.Shared.IoC;
 
 namespace Robust.Client.Console.Commands
 {
-    class HardQuitCommand : IConsoleCommand
+    sealed class HardQuitCommand : IConsoleCommand
     {
         public string Command => "hardquit";
         public string Description => "Kills the game client instantly.";
@@ -16,7 +16,7 @@ namespace Robust.Client.Console.Commands
         }
     }
 
-    class QuitCommand : IConsoleCommand
+    sealed class QuitCommand : IConsoleCommand
     {
         public string Command => "quit";
         public string Description => "Shuts down the game client gracefully.";

Robust.Client/Console/Commands/SetInputContextCommand.cs

@@ -6,7 +6,7 @@ using Robust.Shared.IoC;
 namespace Robust.Client.Console.Commands
 {
     [UsedImplicitly]
-    public class SetInputContextCommand : IConsoleCommand
+    public sealed class SetInputContextCommand : IConsoleCommand
     {
         public string Command => "setinputcontext";
         public string Description => "Sets the active input context.";

Robust.Client/Console/Commands/VelocitiesCommand.cs

@@ -4,7 +4,7 @@ using Robust.Shared.GameObjects;
 
 namespace Robust.Client.Console.Commands
 {
-    public class VelocitiesCommand : IConsoleCommand
+    public sealed class VelocitiesCommand : IConsoleCommand
     {
         public string Command => "showvelocities";
         public string Description => "Displays your angular and linear velocities";

Robust.Client/Console/Completions.cs

@@ -11,7 +11,7 @@ using static Robust.Shared.Network.Messages.MsgScriptCompletionResponse;
 
 namespace Robust.Client.Console
 {
-    public class Completions : DefaultWindow
+    public sealed class Completions : DefaultWindow
     {
         private HistoryLineEdit _textBar;
         private ScrollContainer _suggestPanel = new()
@@ -75,7 +75,7 @@ namespace Robust.Client.Console
         }
 
         // Label and ghetto button.
-        public class Entry : RichTextLabel
+        public sealed class Entry : RichTextLabel
         {
             public readonly LiteResult Result;
 

Robust.Client/Console/ScriptClient.cs

@@ -6,7 +6,7 @@ using Robust.Shared.Network.Messages;
 
 namespace Robust.Client.Console
 {
-    public partial class ScriptClient : IScriptClient
+    public sealed partial class ScriptClient : IScriptClient
     {
         [Dependency] private readonly IClientConGroupController _conGroupController = default!;
         [Dependency] private readonly IClientNetManager _netManager = default!;

Robust.Client/Console/WatchWindow.cs

@@ -15,7 +15,7 @@ using static Robust.Client.UserInterface.Controls.BoxContainer;
 
 namespace Robust.Client.Console
 {
-    public class WatchWindow : DefaultWindow
+    public sealed class WatchWindow : DefaultWindow
     {
         private readonly IReflectionManager _reflectionManager;
 

Robust.Client/Debugging/DebugDrawing.cs

@@ -7,7 +7,7 @@ using Robust.Shared.Maths;
 namespace Robust.Client.Debugging
 {
     /// <inheritdoc />
-    public class DebugDrawing : IDebugDrawing
+    public sealed class DebugDrawing : IDebugDrawing
     {
         [Dependency] private readonly IOverlayManager _overlayManager = default!;
         [Dependency] private readonly IEyeManager _eyeManager = default!;

Robust.Client/Debugging/DebugPhysicsSystem.cs

@@ -209,8 +209,8 @@ namespace Robust.Client.Debugging
 
                     foreach (var fixture in _entityManager.GetComponent<FixturesComponent>(physBody.Owner).Fixtures.Values)
                     {
-                        // Invalid shape - Box2D doesn't check for IsSensor
-                        if (physBody.BodyType == BodyType.Dynamic && fixture.Mass == 0f)
+                        // Invalid shape - Box2D doesn't check for IsSensor but we will for sanity.
+                        if (physBody.BodyType == BodyType.Dynamic && fixture.Mass == 0f && fixture.Hard)
                         {
                             DrawShape(worldHandle, fixture, xform, Color.Red.WithAlpha(AlphaModifier));
                         }

Robust.Client/GameController/GameController.Loader.cs

@@ -7,7 +7,7 @@ namespace Robust.Client
 {
     internal partial class GameController
     {
-        internal class LoaderEntryPoint : ILoaderEntryPoint
+        internal sealed class LoaderEntryPoint : ILoaderEntryPoint
         {
             public void Main(IMainArgs args)
             {

Robust.Client/GameControllerOptions.cs

@@ -3,7 +3,7 @@ using Robust.Shared.Utility;
 
 namespace Robust.Client
 {
-    public class GameControllerOptions
+    public sealed class GameControllerOptions
     {
         /// <summary>
         ///     Whether content sandboxing will be enabled & enforced.

Robust.Client/GameObjects/ClientComponentFactory.cs

@@ -6,7 +6,7 @@ using Robust.Shared.Reflection;
 
 namespace Robust.Client.GameObjects
 {
-    internal class ClientComponentFactory : ComponentFactory
+    internal sealed class ClientComponentFactory : ComponentFactory
     {
         public ClientComponentFactory(IDynamicTypeFactoryInternal typeFactory, IReflectionManager reflectionManager, IConsoleHost conHost)
             : base(typeFactory, reflectionManager, conHost)

Robust.Client/GameObjects/ComponentStateApplyException.cs

@@ -4,6 +4,7 @@ using System.Runtime.Serialization;
 namespace Robust.Client.GameObjects
 {
     [Serializable]
+    [Virtual]
     public class ComponentStateApplyException : Exception
     {
         public ComponentStateApplyException()

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

@@ -1,4 +1,5 @@
-using Robust.Shared.GameObjects;
+using System;
+using Robust.Shared.GameObjects;
 using Robust.Shared.Serialization.Manager.Attributes;
 
 namespace Robust.Client.GameObjects;
@@ -14,6 +15,7 @@ public abstract class AppearanceVisualizer
     ///     Initializes an entity to be managed by this appearance controller.
     ///     DO NOT assume this is your only entity. Visualizers are shared.
     /// </summary>
+    [Obsolete("Subscribe to your component being initialised instead.")]
     public virtual void InitializeEntity(EntityUid entity)
     {
     }
@@ -23,6 +25,7 @@ public abstract class AppearanceVisualizer
     ///     Update its visuals here.
     /// </summary>
     /// <param name="component">The appearance component of the entity that might need updating.</param>
+    [Obsolete("Subscribe to AppearanceChangeEvent instead.")]
     public virtual void OnChangeData(AppearanceComponent component)
     {
     }

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

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using Robust.Shared.Analyzers;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Serialization.Manager.Attributes;
 using Robust.Shared.ViewVariables;
@@ -9,39 +10,10 @@ namespace Robust.Client.GameObjects;
 /// This is the client instance of <see cref="AppearanceComponent"/>.
 /// </summary>
 [RegisterComponent]
-[ComponentReference(typeof(AppearanceComponent))]
+[ComponentReference(typeof(AppearanceComponent)), Friend(typeof(AppearanceSystem))]
 public sealed class ClientAppearanceComponent : AppearanceComponent
 {
-    [ViewVariables]
-    private bool _appearanceDirty;
-
     [ViewVariables]
     [DataField("visuals")]
     internal List<AppearanceVisualizer> Visualizers = new();
-
-    protected override void MarkDirty()
-    {
-        if (_appearanceDirty)
-            return;
-
-        EntitySystem.Get<AppearanceSystem>().EnqueueUpdate(this);
-        _appearanceDirty = true;
-    }
-
-    protected override void Initialize()
-    {
-        base.Initialize();
-
-        foreach (var visual in Visualizers)
-        {
-            visual.InitializeEntity(Owner);
-        }
-
-        MarkDirty();
-    }
-
-    internal void UnmarkDirty()
-    {
-        _appearanceDirty = false;
-    }
 }

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

@@ -9,7 +9,7 @@ using Robust.Shared.ViewVariables;
 namespace Robust.Client.GameObjects
 {
     [ComponentReference(typeof(SharedEyeComponent))]
-    public class EyeComponent : SharedEyeComponent
+    public sealed class EyeComponent : SharedEyeComponent
     {
         [Dependency] private readonly IEyeManager _eyeManager = default!;
         [Dependency] private readonly IEntityManager _entityManager = default!;

Robust.Client/GameObjects/Components/Icon/IconComponent.cs

@@ -12,7 +12,7 @@ using Robust.Shared.Utility;
 namespace Robust.Client.GameObjects
 {
     [RegisterComponent]
-    public class IconComponent : Component, ISerializationHooks
+    public sealed class IconComponent : Component, ISerializationHooks
     {
         public IDirectionalTextureProvider? Icon { get; private set; }
 

Robust.Client/GameObjects/Components/Input/InputComponent.cs

@@ -8,7 +8,7 @@ namespace Robust.Client.GameObjects
     /// <summary>
     ///     Defines data fields used in the <see cref="InputSystem"/>.
     /// </summary>
-    public class InputComponent : Component
+    public sealed class InputComponent : Component
     {
         /// <summary>
         ///     The context that will be made active for a client that attaches to this entity.

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

@@ -40,13 +40,14 @@ namespace Robust.Client.GameObjects
 
         public void AnchorStateChanged()
         {
-            SendDirty();
+            var xform = _entityManager.GetComponent<TransformComponent>(Owner);
+            SendDirty(xform);
 
-            if(!_entityManager.GetComponent<TransformComponent>(Owner).Anchored)
+            if(!xform.Anchored)
                 return;
 
-            var grid = _mapManager.GetGrid(_entityManager.GetComponent<TransformComponent>(Owner).GridID);
-            _lastPosition = (_entityManager.GetComponent<TransformComponent>(Owner).GridID, grid.TileIndicesFor(_entityManager.GetComponent<TransformComponent>(Owner).Coordinates));
+            var grid = _mapManager.GetGrid(xform.GridID);
+            _lastPosition = (xform.GridID, grid.TileIndicesFor(xform.Coordinates));
         }
 
         protected override void Shutdown()
@@ -56,9 +57,10 @@ namespace Robust.Client.GameObjects
             SendDirty();
         }
 
-        private void SendDirty()
+        private void SendDirty(TransformComponent? xform = null)
         {
-            if (_entityManager.GetComponent<TransformComponent>(Owner).Anchored)
+            xform ??= _entityManager.GetComponent<TransformComponent>(Owner);
+            if (xform.Anchored)
             {
                 _entityManager.EventBus.RaiseEvent(EventSource.Local,
                     new OccluderDirtyEvent(Owner, _lastPosition));

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

@@ -11,7 +11,7 @@ namespace Robust.Client.GameObjects
 {
     [RegisterComponent]
     [ComponentReference(typeof(SharedPointLightComponent))]
-    public class PointLightComponent : SharedPointLightComponent, ISerializationHooks
+    public sealed class PointLightComponent : SharedPointLightComponent, ISerializationHooks
     {
         [Dependency] private readonly IEntityManager _entityManager = default!;
 
@@ -139,7 +139,7 @@ namespace Robust.Client.GameObjects
         internal RenderingTreeComponent? RenderTree { get; set; }
     }
 
-    public class PointLightRadiusChangedEvent : EntityEventArgs
+    public sealed class PointLightRadiusChangedEvent : EntityEventArgs
     {
         public PointLightComponent PointLightComponent { get; }
 

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

@@ -57,7 +57,7 @@ namespace Robust.Client.GameObjects
         private bool _enabled;
     }
 
-    public class SpriteBoundsOverlay : Overlay
+    public sealed class SpriteBoundsOverlay : Overlay
     {
         public override OverlaySpace Space => OverlaySpace.WorldSpace;
 

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

@@ -1477,30 +1477,6 @@ namespace Robust.Client.GameObjects
             }
         }
 
-        private RSI.State.Direction GetDir(RSI.State.DirectionType rsiDirectionType, Angle worldRotation)
-        {
-            var dir = rsiDirectionType switch
-            {
-                RSI.State.DirectionType.Dir1 => Direction.South,
-                RSI.State.DirectionType.Dir4 => worldRotation.GetCardinalDir(),
-                RSI.State.DirectionType.Dir8 => worldRotation.GetDir(),
-                _ => throw new ArgumentException($"Unknown RSI DirectionType: {rsiDirectionType}.", nameof(rsiDirectionType))
-            };
-
-            return dir switch
-            {
-                Direction.North => RSI.State.Direction.North,
-                Direction.South => RSI.State.Direction.South,
-                Direction.East => RSI.State.Direction.East,
-                Direction.West => RSI.State.Direction.West,
-                Direction.SouthEast => RSI.State.Direction.SouthEast,
-                Direction.SouthWest => RSI.State.Direction.SouthWest,
-                Direction.NorthEast => RSI.State.Direction.NorthEast,
-                Direction.NorthWest => RSI.State.Direction.NorthWest,
-                _ => throw new ArgumentOutOfRangeException(nameof(dir), dir, null)
-            };
-        }
-
         private void QueueUpdateIsInert()
         {
             // Look this was an easy way to get bounds checks for layer updates.
@@ -1550,58 +1526,13 @@ namespace Robust.Client.GameObjects
             return rsi["error"];
         }
 
-        private static RSI.State.Direction OffsetRsiDir(RSI.State.Direction dir, DirectionOffset offset)
-        {
-            // There is probably a better way to do this.
-            // Eh.
-            switch (offset)
-            {
-                case DirectionOffset.None:
-                    return dir;
-                case DirectionOffset.Clockwise:
-                    return dir switch
-                    {
-                        RSI.State.Direction.North => RSI.State.Direction.East,
-                        RSI.State.Direction.East => RSI.State.Direction.South,
-                        RSI.State.Direction.South => RSI.State.Direction.West,
-                        RSI.State.Direction.West => RSI.State.Direction.North,
-                        _ => throw new NotImplementedException()
-                    };
-                case DirectionOffset.CounterClockwise:
-                    return dir switch
-                    {
-                        RSI.State.Direction.North => RSI.State.Direction.West,
-                        RSI.State.Direction.East => RSI.State.Direction.North,
-                        RSI.State.Direction.South => RSI.State.Direction.East,
-                        RSI.State.Direction.West => RSI.State.Direction.South,
-                        _ => throw new NotImplementedException()
-                    };
-                case DirectionOffset.Flip:
-                    switch (dir)
-                    {
-                        case RSI.State.Direction.North:
-                            return RSI.State.Direction.South;
-                        case RSI.State.Direction.East:
-                            return RSI.State.Direction.West;
-                        case RSI.State.Direction.South:
-                            return RSI.State.Direction.North;
-                        case RSI.State.Direction.West:
-                            return RSI.State.Direction.East;
-                        default:
-                            throw new NotImplementedException();
-                    }
-                default:
-                    throw new NotImplementedException();
-            }
-        }
-
         public string GetDebugString()
         {
             var builder = new StringBuilder();
             builder.AppendFormat(
                 "vis/depth/scl/rot/ofs/col/norot/override/dir: {0}/{1}/{2}/{3}/{4}/{5}/{6}/{8}/{7}\n",
                 Visible, DrawDepth, Scale, Rotation, Offset,
-                Color, NoRotation, GetDir(RSI.State.DirectionType.Dir8, entities.GetComponent<TransformComponent>(Owner).WorldRotation),
+                Color, NoRotation, entities.GetComponent<TransformComponent>(Owner).WorldRotation.ToRsiDirection(RSI.State.DirectionType.Dir8),
                 DirectionOverride
             );
 
@@ -1684,7 +1615,7 @@ namespace Robust.Client.GameObjects
             Flip = 3,
         }
 
-        public class Layer : ISpriteLayer
+        public sealed class Layer : ISpriteLayer
         {
             [ViewVariables] private readonly SpriteComponent _parent;
 
@@ -1842,10 +1773,10 @@ namespace Robust.Client.GameObjects
                     }
                     else
                     {
-                        dir = _parent.GetDir(state.Directions, worldRotation);
+                        dir = worldRotation.ToRsiDirection(state.Directions);
                     }
 
-                    return OffsetRsiDir(dir, DirOffset);
+                    return dir.OffsetRsiDir(DirOffset);
                 }
             }
 

Robust.Client/GameObjects/Components/UserInterface/ClientUserInterfaceComponent.cs

@@ -11,7 +11,7 @@ using Robust.Shared.ViewVariables;
 namespace Robust.Client.GameObjects
 {
     [ComponentReference(typeof(SharedUserInterfaceComponent))]
-    public class ClientUserInterfaceComponent : SharedUserInterfaceComponent, ISerializationHooks
+    public sealed class ClientUserInterfaceComponent : SharedUserInterfaceComponent, ISerializationHooks
     {
         [Dependency] private readonly IReflectionManager _reflectionManager = default!;
         [Dependency] private readonly IDynamicTypeFactory _dynamicTypeFactory = default!;

Robust.Client/GameObjects/EntitySystems/AnimationPlayerSystem.cs

@@ -62,6 +62,12 @@ namespace Robust.Client.GameObjects
             Play(component, animation, key);
         }
 
+        public void Play(EntityUid uid, AnimationPlayerComponent? component, Animation animation, string key)
+        {
+            component ??= EntityManager.EnsureComponent<AnimationPlayerComponent>(uid);
+            Play(component, animation, key);
+        }
+
         /// <summary>
         ///     Start playing an animation.
         /// </summary>
@@ -79,6 +85,14 @@ namespace Robust.Client.GameObjects
                    component.PlayingAnimations.ContainsKey(key);
         }
 
+        public bool HasRunningAnimation(EntityUid uid, AnimationPlayerComponent? component, string key)
+        {
+            if (component == null)
+                TryComp(uid, out component);
+
+            return component != null && component.PlayingAnimations.ContainsKey(key);
+        }
+
         public bool HasRunningAnimation(AnimationPlayerComponent component, string key)
         {
             return component.PlayingAnimations.ContainsKey(key);
@@ -88,6 +102,18 @@ namespace Robust.Client.GameObjects
         {
             component.PlayingAnimations.Remove(key);
         }
+
+        public void Stop(EntityUid uid, string key)
+        {
+            if (!TryComp<AnimationPlayerComponent>(uid, out var player)) return;
+            player.PlayingAnimations.Remove(key);
+        }
+
+        public void Stop(EntityUid uid, AnimationPlayerComponent? component, string key)
+        {
+            if (!Resolve(uid, ref component, false)) return;
+            component.PlayingAnimations.Remove(key);
+        }
     }
 
     public sealed class AnimationCompletedEvent : EntityEventArgs

Robust.Client/GameObjects/EntitySystems/AppearanceSystem.cs

@@ -1,17 +1,71 @@
 using System.Collections.Generic;
 using JetBrains.Annotations;
 using Robust.Shared.GameObjects;
+using Robust.Shared.GameStates;
 
 namespace Robust.Client.GameObjects
 {
     [UsedImplicitly]
-    internal sealed class AppearanceSystem : EntitySystem
+    internal sealed class AppearanceSystem : SharedAppearanceSystem
     {
         private readonly Queue<ClientAppearanceComponent> _queuedUpdates = new();
 
-        public void EnqueueUpdate(ClientAppearanceComponent component)
+        public override void Initialize()
         {
-            _queuedUpdates.Enqueue(component);
+            base.Initialize();
+
+            SubscribeLocalEvent<ClientAppearanceComponent, ComponentInit>(OnAppearanceInit);
+            SubscribeLocalEvent<ClientAppearanceComponent, ComponentHandleState>(OnAppearanceHandleState);
+        }
+
+        private void OnAppearanceInit(EntityUid uid, ClientAppearanceComponent component, ComponentInit args)
+        {
+            foreach (var visual in component.Visualizers)
+            {
+                visual.InitializeEntity(uid);
+            }
+
+            MarkDirty(component);
+        }
+
+        private void OnAppearanceHandleState(EntityUid uid, ClientAppearanceComponent component, ref ComponentHandleState args)
+        {
+            if (args.Current is not AppearanceComponentState actualState)
+                return;
+
+            var stateDiff = component.AppearanceData.Count != actualState.Data.Count;
+
+            if (!stateDiff)
+            {
+                foreach (var (key, value) in component.AppearanceData)
+                {
+                    if (!actualState.Data.TryGetValue(key, out var stateValue) ||
+                        !value.Equals(stateValue))
+                    {
+                        stateDiff = true;
+                        break;
+                    }
+                }
+            }
+
+            if (!stateDiff) return;
+
+            component.AppearanceData = actualState.Data;
+            MarkDirty(component);
+        }
+
+        public override void MarkDirty(AppearanceComponent component)
+        {
+            if (component.AppearanceDirty)
+                return;
+
+            _queuedUpdates.Enqueue((ClientAppearanceComponent) component);
+            component.AppearanceDirty = true;
+        }
+
+        internal void UnmarkDirty(ClientAppearanceComponent component)
+        {
+            component.AppearanceDirty = false;
         }
 
         public override void FrameUpdate(float frameTime)
@@ -22,7 +76,7 @@ namespace Robust.Client.GameObjects
                     continue;
 
                 OnChangeData(appearance.Owner, appearance);
-                appearance.UnmarkDirty();
+                UnmarkDirty(appearance);
             }
         }
 
@@ -30,10 +84,30 @@ namespace Robust.Client.GameObjects
         {
             if (!Resolve(uid, ref appearanceComponent, false)) return;
 
+            var ev = new AppearanceChangeEvent
+            {
+                Component = appearanceComponent,
+                AppearanceData = appearanceComponent.AppearanceData,
+            };
+
+            // Give it AppearanceData so we can still keep the friend attribute on the component.
+            EntityManager.EventBus.RaiseLocalEvent(uid, ref ev);
+
+            // Eventually visualizers would be nuked and we'd just make them components instead.
             foreach (var visualizer in appearanceComponent.Visualizers)
             {
                 visualizer.OnChangeData(appearanceComponent);
             }
         }
     }
+
+    /// <summary>
+    ///     Raised whenever the appearance data for an entity changes.
+    /// </summary>
+    [ByRefEvent]
+    public struct AppearanceChangeEvent
+    {
+        public AppearanceComponent Component = default!;
+        public IReadOnlyDictionary<object, object> AppearanceData = default!;
+    }
 }

Robust.Client/GameObjects/EntitySystems/AudioSystem.cs

@@ -17,7 +17,7 @@ using Robust.Shared.Utility;
 namespace Robust.Client.GameObjects
 {
     [UsedImplicitly]
-    public class AudioSystem : SharedAudioSystem, IAudioSystem
+    public sealed class AudioSystem : SharedAudioSystem, IAudioSystem
     {
         [Dependency] private readonly IResourceCache _resourceCache = default!;
         [Dependency] private readonly IMapManager _mapManager = default!;
@@ -420,7 +420,7 @@ namespace Robust.Client.GameObjects
             source.IsLooping = audioParams.Value.Loop;
         }
 
-        private class PlayingStream : IPlayingAudioStream
+        private sealed class PlayingStream : IPlayingAudioStream
         {
             public uint? NetIdentifier;
             public IClydeAudioSource Source = default!;

Robust.Client/GameObjects/EntitySystems/ClientOccluderSystem.cs

@@ -72,10 +72,13 @@ namespace Robust.Client.GameObjects
             var sender = ev.Sender;
             if (EntityManager.EntityExists(sender) &&
                 EntityManager.TryGetComponent(sender, out ClientOccluderComponent? iconSmooth)
-                && iconSmooth.Running)
+                && iconSmooth.Initialized)
             {
-                var grid1 = _mapManager.GetGrid(EntityManager.GetComponent<TransformComponent>(sender).GridID);
-                var coords = EntityManager.GetComponent<TransformComponent>(sender).Coordinates;
+                var xform = EntityManager.GetComponent<TransformComponent>(sender);
+                if (!_mapManager.TryGetGrid(xform.GridID, out var grid1))
+                    return;
+
+                var coords = xform.Coordinates;
 
                 _dirtyEntities.Enqueue(sender);
                 AddValidEntities(grid1.GetInDir(coords, Direction.North));
@@ -85,7 +88,7 @@ namespace Robust.Client.GameObjects
             }
 
             // Entity is no longer valid, update around the last position it was at.
-            if (ev.LastPosition.HasValue && _mapManager.TryGetGrid(ev.LastPosition.Value.grid, out var grid))
+            else if (ev.LastPosition.HasValue && _mapManager.TryGetGrid(ev.LastPosition.Value.grid, out var grid))
             {
                 var pos = ev.LastPosition.Value.pos;
 

Robust.Client/GameObjects/EntitySystems/ContainerSystem.cs

@@ -5,12 +5,14 @@ using Robust.Shared.Containers;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameStates;
 using Robust.Shared.IoC;
+using Robust.Shared.Log;
+using Robust.Shared.Map;
 using Robust.Shared.Serialization;
 using static Robust.Shared.Containers.ContainerManagerComponent;
 
 namespace Robust.Client.GameObjects
 {
-    public class ContainerSystem : SharedContainerSystem
+    public sealed class ContainerSystem : SharedContainerSystem
     {
         [Dependency] private readonly IRobustSerializer _serializer = default!;
         [Dependency] private readonly IDynamicTypeFactoryInternal _dynFactory = default!;
@@ -59,7 +61,7 @@ namespace Robust.Client.GameObjects
             {
                 if (!cast.ContainerSet.Any(data => data.Id == id))
                 {
-                    container.EmptyContainer(true);
+                    container.EmptyContainer(true, entMan: EntityManager);
                     container.Shutdown();
                     toDelete ??= new List<string>();
                     toDelete.Add(id);
@@ -131,12 +133,51 @@ namespace Robust.Client.GameObjects
                         continue;
                     }
 
+                    // If an entity is currently in the shadow realm, it means we probably left PVS and are now getting
+                    // back into range. We do not want to directly insert this entity, as IF the container and entity
+                    // transform states did not get sent simultaneously, the entity's transform will be modified by the
+                    // insert operation. This means it will then be reset to the shadow realm, causing it to be ejected
+                    // from the container. It would then subsequently be parented to the container without ever being
+                    // re-inserted, leading to the client seeing what should be hidden entities attached to
+                    // containers/players.
+                    if (Transform(entity).MapID == MapId.Nullspace)
+                    {
+                        AddExpectedEntity(entity, container);
+                        continue;
+                    }
+
                     if (!container.ContainedEntities.Contains(entity))
                         container.Insert(entity);
                 }
             }
         }
 
+        protected override void HandleParentChanged(ref EntParentChangedMessage message)
+        {
+            base.HandleParentChanged(ref message);
+
+            // If an entity warped in from null-space (i.e., re-entered PVS) and got attached to a container, do the same checks as for newly initialized entities.
+            if (message.OldParent != null && message.OldParent.Value.IsValid())
+                return;
+
+            if (!ExpectedEntities.TryGetValue(message.Entity, out var container))
+                return;
+
+            if (Transform(message.Entity).ParentUid != container.Owner)
+            {
+                // This container is expecting an entity... but it got parented to some other entity???
+                // Ah well, the sever should send a new container state that updates expected entities so just ignore it for now.
+                return;
+            }    
+
+            RemoveExpectedEntity(message.Entity);
+
+            if (container.Deleted)
+                return;
+
+            container.Insert(message.Entity);
+        }
+
         private IContainer ContainerFactory(ContainerManagerComponent component, string containerType, string id)
         {
             var type = _serializer.FindSerializedType(typeof(IContainer), containerType);

Robust.Client/GameObjects/EntitySystems/EffectSystem.cs

@@ -15,7 +15,7 @@ using Robust.Shared.Enums;
 
 namespace Robust.Client.GameObjects
 {
-    public class EffectSystem : EntitySystem
+    public sealed class EffectSystem : EntitySystem
     {
         [Dependency] private readonly IGameTiming gameTiming = default!;
         [Dependency] private readonly IResourceCache resourceCache = default!;
@@ -94,7 +94,7 @@ namespace Robust.Client.GameObjects
             }
         }
 
-        private class Effect
+        private sealed class Effect
         {
             /// <summary>
             /// Effect Sprite

Robust.Client/GameObjects/EntitySystems/EyeUpdateSystem.cs

@@ -20,7 +20,7 @@ namespace Robust.Client.GameObjects
     /// Updates the position of every Eye every frame, so that the camera follows the player around.
     /// </summary>
     [UsedImplicitly]
-    public class EyeUpdateSystem : EntitySystem
+    public sealed class EyeUpdateSystem : EntitySystem
     {
         /// <inheritdoc />
         public override void Initialize()

Robust.Client/GameObjects/EntitySystems/GridChunkBoundsDebugSystem.cs

@@ -10,7 +10,7 @@ using Robust.Shared.Utility;
 
 namespace Robust.Client.GameObjects
 {
-    public class GridChunkBoundsDebugSystem : EntitySystem
+    public sealed class GridChunkBoundsDebugSystem : EntitySystem
     {
         [Dependency] private readonly IEyeManager _eyeManager = default!;
         [Dependency] private readonly IMapManager _mapManager = default!;

Robust.Client/GameObjects/EntitySystems/InputSystem.cs

@@ -16,7 +16,7 @@ namespace Robust.Client.GameObjects
     /// <summary>
     ///     Client-side processing of all input commands through the simulation.
     /// </summary>
-    public class InputSystem : SharedInputSystem
+    public sealed class InputSystem : SharedInputSystem
     {
         [Dependency] private readonly IInputManager _inputManager = default!;
         [Dependency] private readonly IPlayerManager _playerManager = default!;
@@ -163,7 +163,7 @@ namespace Robust.Client.GameObjects
     /// <summary>
     ///     Entity system message that is raised when the player changes attached entities.
     /// </summary>
-    public class PlayerAttachSysMessage : EntityEventArgs
+    public sealed class PlayerAttachSysMessage : EntityEventArgs
     {
         /// <summary>
         ///     New entity the player is attached to.
@@ -180,7 +180,7 @@ namespace Robust.Client.GameObjects
         }
     }
 
-    public class PlayerAttachedEvent : EntityEventArgs
+    public sealed class PlayerAttachedEvent : EntityEventArgs
     {
         public PlayerAttachedEvent(EntityUid entity)
         {
@@ -190,7 +190,7 @@ namespace Robust.Client.GameObjects
         public EntityUid Entity { get; }
     }
 
-    public class PlayerDetachedEvent : EntityEventArgs
+    public sealed class PlayerDetachedEvent : EntityEventArgs
     {
         public PlayerDetachedEvent(EntityUid entity)
         {

Robust.Client/GameObjects/EntitySystems/MidiSystem.cs

@@ -4,7 +4,7 @@ using Robust.Shared.IoC;
 
 namespace Robust.Client.GameObjects
 {
-    public class MidiSystem : EntitySystem
+    public sealed class MidiSystem : EntitySystem
     {
         [Dependency] private readonly IMidiManager _midiManager = default!;
 

Robust.Client/GameObjects/EntitySystems/RenderingTreeSystem.cs

@@ -113,10 +113,12 @@ namespace Robust.Client.GameObjects
 
         private void AnythingMoved(ref MoveEvent args)
         {
-            AnythingMovedSubHandler(args.Sender);
+            var xforms = EntityManager.GetEntityQuery<TransformComponent>();
+
+            AnythingMovedSubHandler(args.Sender, xforms);
         }
 
-        private void AnythingMovedSubHandler(EntityUid uid, TransformComponent? xform = null)
+        private void AnythingMovedSubHandler(EntityUid uid, EntityQuery<TransformComponent> xforms)
         {
             // To avoid doing redundant updates (and we don't need to update a grid's children ever)
             if (!_checkedChildren.Add(uid) || EntityManager.HasComponent<RenderingTreeComponent>(uid)) return;
@@ -131,11 +133,11 @@ namespace Robust.Client.GameObjects
             if (EntityManager.TryGetComponent(uid, out PointLightComponent? light))
                 QueueLightUpdate(light);
 
-            if (!Resolve(uid, ref xform)) return;
+            if (!xforms.TryGetComponent(uid, out var xform)) return;
 
             foreach (var child in xform.ChildEntities)
             {
-                AnythingMovedSubHandler(child);
+                AnythingMovedSubHandler(child, xforms);
             }
         }
 
@@ -248,23 +250,21 @@ namespace Robust.Client.GameObjects
             EntityManager.EnsureComponent<RenderingTreeComponent>(_mapManager.GetGrid(gridId).GridEntityId);
         }
 
-        // TODO: Pass in TransformComponent directly: mainly interested in getting this shit working atm.
-        private RenderingTreeComponent? GetRenderTree(EntityUid entity)
+        private RenderingTreeComponent? GetRenderTree(EntityUid entity, EntityQuery<TransformComponent> xforms)
         {
+            var lookups = EntityManager.GetEntityQuery<RenderingTreeComponent>();
+
             if (!EntityManager.EntityExists(entity) ||
-                !EntityManager.TryGetComponent(entity, out TransformComponent? xform) ||
+                !xforms.TryGetComponent(entity, out var xform) ||
                 xform.MapID == MapId.Nullspace ||
-                EntityManager.HasComponent<RenderingTreeComponent>(entity)) return null;
+                lookups.HasComponent(entity)) return null;
 
             var parent = xform.ParentUid;
 
-            while (true)
+            while (parent.IsValid())
             {
-                if (!parent.IsValid())
-                    break;
-
-                if (EntityManager.TryGetComponent(parent, out RenderingTreeComponent? comp)) return comp;
-                parent = EntityManager.GetComponent<TransformComponent>(parent).ParentUid;
+                if (lookups.TryGetComponent(parent, out var comp)) return comp;
+                parent = xforms.GetComponent(parent).ParentUid;
             }
 
             return null;
@@ -279,6 +279,8 @@ namespace Robust.Client.GameObjects
         {
             _checkedChildren.Clear();
 
+            var xforms = EntityManager.GetEntityQuery<TransformComponent>();
+
             foreach (var sprite in _spriteQueue)
             {
                 sprite.TreeUpdateQueued = false;
@@ -289,9 +291,9 @@ namespace Robust.Client.GameObjects
                 }
 
                 var oldMapTree = sprite.RenderTree;
-                var newMapTree = GetRenderTree(sprite.Owner);
+                var newMapTree = GetRenderTree(sprite.Owner, xforms);
                 // TODO: Temp PVS guard
-                var xform = EntityManager.GetComponent<TransformComponent>(sprite.Owner);
+                var xform = xforms.GetComponent(sprite.Owner);
                 var (worldPos, worldRot) = xform.GetWorldPositionRotation();
 
                 if (float.IsNaN(worldPos.X) || float.IsNaN(worldPos.Y))
@@ -300,7 +302,7 @@ namespace Robust.Client.GameObjects
                     continue;
                 }
 
-                var aabb = SpriteAabbFunc(sprite, worldPos, worldRot);
+                var aabb = SpriteAabbFunc(sprite, worldPos, worldRot, xforms);
 
                 // If we're on a new map then clear the old one.
                 if (oldMapTree != newMapTree)
@@ -327,9 +329,9 @@ namespace Robust.Client.GameObjects
                 }
 
                 var oldMapTree = light.RenderTree;
-                var newMapTree = GetRenderTree(light.Owner);
+                var newMapTree = GetRenderTree(light.Owner, xforms);
                 // TODO: Temp PVS guard
-                var worldPos = EntityManager.GetComponent<TransformComponent>(light.Owner).WorldPosition;
+                var worldPos = xforms.GetComponent(light.Owner).WorldPosition;
 
                 if (float.IsNaN(worldPos.X) || float.IsNaN(worldPos.Y))
                 {
@@ -344,7 +346,7 @@ namespace Robust.Client.GameObjects
                     Logger.WarningS(LoggerSawmill, $"Light radius for {light.Owner} set above max radius of {MaxLightRadius}. This may lead to pop-in.");
                 }
 
-                var aabb = LightAabbFunc(light, worldPos);
+                var aabb = LightAabbFunc(light, worldPos, xforms);
 
                 // If we're on a new map then clear the old one.
                 if (oldMapTree != newMapTree)
@@ -366,69 +368,43 @@ namespace Robust.Client.GameObjects
 
         private Box2 SpriteAabbFunc(in SpriteComponent value)
         {
-            var xform = EntityManager.GetComponent<TransformComponent>(value.Owner);
+            var xforms = EntityManager.GetEntityQuery<TransformComponent>();
+
+            var xform = xforms.GetComponent(value.Owner);
             var (worldPos, worldRot) = xform.GetWorldPositionRotation();
             var bounds = new Box2Rotated(value.CalculateBoundingBox(worldPos), worldRot, worldPos);
-            var tree = GetRenderTree(value.Owner);
+            var tree = GetRenderTree(value.Owner, xforms);
 
-            if (tree == null)
-            {
-                return bounds.CalcBoundingBox();
-            }
-            else
-            {
-                return EntityManager.GetComponent<TransformComponent>(tree.Owner).InvWorldMatrix.TransformBox(bounds);
-            }
+            return tree == null ? bounds.CalcBoundingBox() : xforms.GetComponent(tree.Owner).InvWorldMatrix.TransformBox(bounds);
         }
 
         private Box2 LightAabbFunc(in PointLightComponent value)
         {
-            var worldPos = EntityManager.GetComponent<TransformComponent>(value.Owner).WorldPosition;
-            var tree = GetRenderTree(value.Owner);
+            var xforms = EntityManager.GetEntityQuery<TransformComponent>();
+
+            var worldPos = xforms.GetComponent(value.Owner).WorldPosition;
+            var tree = GetRenderTree(value.Owner, xforms);
             var boxSize = value.Radius * 2;
 
-            Vector2 localPos;
-            if (tree == null)
-            {
-                localPos = worldPos;
-            }
-            else
-            {
-                // TODO: Need a way to just cache this InvWorldMatrix
-                localPos = EntityManager.GetComponent<TransformComponent>(tree.Owner).InvWorldMatrix.Transform(worldPos);
-            }
+            var localPos = tree == null ? worldPos : xforms.GetComponent(tree.Owner).InvWorldMatrix.Transform(worldPos);
             return Box2.CenteredAround(localPos, (boxSize, boxSize));
         }
 
-        private Box2 SpriteAabbFunc(SpriteComponent value, Vector2 worldPos, Angle worldRot)
+        private Box2 SpriteAabbFunc(SpriteComponent value, Vector2 worldPos, Angle worldRot, EntityQuery<TransformComponent> xforms)
         {
             var bounds = new Box2Rotated(value.CalculateBoundingBox(worldPos), worldRot, worldPos);
-            var tree = GetRenderTree(value.Owner);
+            var tree = GetRenderTree(value.Owner, xforms);
 
-            if (tree == null)
-            {
-                return bounds.CalcBoundingBox();
-            }
-            else
-            {
-                return EntityManager.GetComponent<TransformComponent>(tree.Owner).InvWorldMatrix.TransformBox(bounds);
-            }
+            return tree == null ? bounds.CalcBoundingBox() : xforms.GetComponent(tree.Owner).InvWorldMatrix.TransformBox(bounds);
         }
 
-        private Box2 LightAabbFunc(PointLightComponent value, Vector2 worldPos)
+        private Box2 LightAabbFunc(PointLightComponent value, Vector2 worldPos, EntityQuery<TransformComponent> xforms)
         {
             // Lights are circles so don't need entity's rotation
-            var tree = GetRenderTree(value.Owner);
+            var tree = GetRenderTree(value.Owner, xforms);
             var boxSize = value.Radius * 2;
 
-            Vector2 localPos;
-            if (tree == null)
-            {
-                localPos = worldPos;
-            } else
-            {
-                localPos = EntityManager.GetComponent<TransformComponent>(tree.Owner).InvWorldMatrix.Transform(worldPos);
-            }
+            var localPos = tree == null ? worldPos : xforms.GetComponent(tree.Owner).InvWorldMatrix.Transform(worldPos);
             return Box2.CenteredAround(localPos, (boxSize, boxSize));
         }
     }

Robust.Client/GameObjects/EntitySystems/SpriteSystem.cs

@@ -11,7 +11,7 @@ namespace Robust.Client.GameObjects
     /// Updates the layer animation for every visible sprite.
     /// </summary>
     [UsedImplicitly]
-    public class SpriteSystem : EntitySystem
+    public sealed class SpriteSystem : EntitySystem
     {
         [Dependency] private readonly IEyeManager _eyeManager = default!;
         [Dependency] private readonly RenderingTreeSystem _treeSystem = default!;
@@ -53,9 +53,11 @@ namespace Robust.Client.GameObjects
                 return;
             }
 
+            var xforms = EntityManager.GetEntityQuery<TransformComponent>();
+
             foreach (var comp in _treeSystem.GetRenderTrees(currentMap, pvsBounds))
             {
-                var bounds = EntityManager.GetComponent<TransformComponent>(comp.Owner).InvWorldMatrix.TransformBox(pvsBounds);
+                var bounds = xforms.GetComponent(comp.Owner).InvWorldMatrix.TransformBox(pvsBounds);
 
                 comp.SpriteTree.QueryAabb(ref frameTime, (ref float state, in SpriteComponent value) =>
                 {

Robust.Client/GameObjects/EntitySystems/VelocityDebugSystem.cs

@@ -8,7 +8,7 @@ using Robust.Shared.Maths;
 
 namespace Robust.Client.GameObjects
 {
-    public class VelocityDebugSystem : EntitySystem
+    public sealed class VelocityDebugSystem : EntitySystem
     {
         [Dependency] private readonly IEyeManager _eyeManager = default!;
         [Dependency] private readonly IPlayerManager _playerManager = default!;

Robust.Client/GameObjects/EntitySystems/VisualizerSystem.cs

@@ -0,0 +1,20 @@
+using Robust.Shared.GameObjects;
+
+namespace Robust.Client.GameObjects;
+
+/// <summary>
+///     An abstract entity system inheritor for systems that deal with
+///     appearance data, replacing <see cref="AppearanceVisualizer"/>.
+/// </summary>
+public abstract class VisualizerSystem<T> : EntitySystem
+    where T: Component
+{
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<T, AppearanceChangeEvent>(OnAppearanceChange);
+    }
+
+    protected virtual void OnAppearanceChange(EntityUid uid, T component, ref AppearanceChangeEvent args) {}
+}

Robust.Client/GameStates/ClientGameStateManager.cs

@@ -7,7 +7,6 @@ using System.Linq;
 using JetBrains.Annotations;
 using Robust.Client.GameObjects;
 using Robust.Client.Input;
-using Robust.Client.Map;
 using Robust.Client.Player;
 using Robust.Client.Timing;
 using Robust.Shared;
@@ -29,7 +28,7 @@ namespace Robust.Client.GameStates
 {
     /// <inheritdoc />
     [UsedImplicitly]
-    public class ClientGameStateManager : IClientGameStateManager
+    public sealed class ClientGameStateManager : IClientGameStateManager
     {
         private GameStateProcessor _processor = default!;
 
@@ -50,7 +49,7 @@ namespace Robust.Client.GameStates
         [Dependency] private readonly IPlayerManager _players = default!;
         [Dependency] private readonly IClientNetManager _network = default!;
         [Dependency] private readonly IBaseClient _client = default!;
-        [Dependency] private readonly IClientMapManager _mapManager = default!;
+        [Dependency] private readonly INetworkedMapManager _mapManager = default!;
         [Dependency] private readonly IClientGameTiming _timing = default!;
         [Dependency] private readonly INetConfigurationManager _config = default!;
         [Dependency] private readonly IEntitySystemManager _entitySystemManager = default!;
@@ -60,6 +59,8 @@ namespace Robust.Client.GameStates
         [Dependency] private readonly IRuntimeLog _runtimeLog = default!;
 #endif
 
+        private ISawmill _sawmill = default!;
+
         /// <inheritdoc />
         public int MinBufferSize => _processor.MinBufferSize;
 
@@ -87,6 +88,7 @@ namespace Robust.Client.GameStates
         /// <inheritdoc />
         public void Initialize()
         {
+            _sawmill = Logger.GetSawmill(CVars.NetPredict.Name);
             _processor = new GameStateProcessor(_timing);
 
             _network.RegisterNetMessage<MsgState>(HandleStateMessage);
@@ -144,7 +146,7 @@ namespace Robust.Client.GameStates
             _pendingInputs.Enqueue(message);
 
             _inputManager.NetworkBindMap.TryGetKeyFunction(message.InputFunctionId, out var boundFunc);
-            Logger.DebugS(CVars.NetPredict.Name,
+            _sawmill.Debug(
                 $"CL> SENT tick={_timing.CurTick}, sub={_timing.TickFraction}, seq={_nextInputCmdSeq}, func={boundFunc.FunctionName}, state={message.State}");
             _nextInputCmdSeq++;
         }
@@ -238,7 +240,7 @@ namespace Robust.Client.GameStates
 
                 if (_lastProcessedSeq < curState.LastProcessedInput)
                 {
-                    Logger.DebugS(CVars.NetPredict.Name, $"SV> RCV  tick={_timing.CurTick}, seq={_lastProcessedSeq}");
+                    _sawmill.Debug($"SV> RCV  tick={_timing.CurTick}, seq={_lastProcessedSeq}");
                     _lastProcessedSeq = curState.LastProcessedInput;
                 }
             }
@@ -257,8 +259,7 @@ namespace Robust.Client.GameStates
                 var inCmd = _pendingInputs.Dequeue();
 
                 _inputManager.NetworkBindMap.TryGetKeyFunction(inCmd.InputFunctionId, out var boundFunc);
-                Logger.DebugS(CVars.NetPredict.Name,
-                    $"SV>     seq={inCmd.InputSequence}, func={boundFunc.FunctionName}, state={inCmd.State}");
+                _sawmill.Debug($"SV>     seq={inCmd.InputSequence}, func={boundFunc.FunctionName}, state={inCmd.State}");
             }
 
             while (_pendingSystemMessages.Count > 0 && _pendingSystemMessages.Peek().sequence <= _lastProcessedSeq)
@@ -274,7 +275,7 @@ namespace Robust.Client.GameStates
 
                 if (_pendingInputs.Count > 0)
                 {
-                    Logger.DebugS(CVars.NetPredict.Name,  "CL> Predicted:");
+                    _sawmill.Debug("CL> Predicted:");
                 }
 
                 var pendingInputEnumerator = _pendingInputs.GetEnumerator();
@@ -299,7 +300,7 @@ namespace Robust.Client.GameStates
 
                         _inputManager.NetworkBindMap.TryGetKeyFunction(inputCmd.InputFunctionId, out var boundFunc);
 
-                        Logger.DebugS(CVars.NetPredict.Name,
+                        _sawmill.Debug(
                             $"    seq={inputCmd.InputSequence}, sub={inputCmd.SubTick}, dTick={tick}, func={boundFunc.FunctionName}, " +
                             $"state={inputCmd.State}");
 
@@ -347,7 +348,11 @@ namespace Robust.Client.GameStates
                     continue;
                 }
 
-                Logger.DebugS(CVars.NetPredict.Name, $"Entity {entity} was made dirty.");
+                // Check log level first to avoid the string alloc.
+                if (_sawmill.Level <= LogLevel.Debug)
+                {
+                    _sawmill.Debug($"Entity {entity} was made dirty.");
+                }
 
                 if (!_processor.TryGetLastServerStates(entity, out var last))
                 {
@@ -365,7 +370,7 @@ namespace Robust.Client.GameStates
                         continue;
                     }
 
-                    Logger.DebugS(CVars.NetPredict.Name, $"  And also its component {comp.GetType()}");
+                    _sawmill.Debug($"  And also its component {comp.GetType()}");
                     // TODO: Handle interpolation.
                     var handleState = new ComponentHandleState(compState, null);
                     _entities.EventBus.RaiseComponentEvent(comp, ref handleState);
@@ -632,7 +637,7 @@ namespace Robust.Client.GameStates
         }
     }
 
-    public class GameStateAppliedArgs : EventArgs
+    public sealed class GameStateAppliedArgs : EventArgs
     {
         public GameState AppliedState { get; }
 

Robust.Client/GameStates/GameStateProcessor.cs

@@ -10,7 +10,7 @@ using Robust.Shared.Utility;
 namespace Robust.Client.GameStates
 {
     /// <inheritdoc />
-    internal class GameStateProcessor : IGameStateProcessor
+    internal sealed class GameStateProcessor : IGameStateProcessor
     {
         private readonly IGameTiming _timing;
 

Robust.Client/GameStates/NetEntityOverlay.cs

@@ -19,7 +19,7 @@ namespace Robust.Client.GameStates
     /// A network entity report that lists all entities as they are updated through game states.
     /// https://developer.valvesoftware.com/wiki/Networking_Entities#cl_entityreport
     /// </summary>
-    class NetEntityOverlay : Overlay
+    sealed class NetEntityOverlay : Overlay
     {
         [Dependency] private readonly IGameTiming _gameTiming = default!;
         [Dependency] private readonly IClientNetManager _netManager = default!;
@@ -244,7 +244,7 @@ namespace Robust.Client.GameStates
             }
         }
 
-        private class NetEntityReportCommand : IConsoleCommand
+        private sealed class NetEntityReportCommand : IConsoleCommand
         {
             public string Command => "net_entityreport";
             public string Help => "net_entityreport <0|1>";

Robust.Client/GameStates/NetGraphOverlay.cs

@@ -16,7 +16,7 @@ namespace Robust.Client.GameStates
     /// <summary>
     ///     Visual debug overlay for the network diagnostic graph.
     /// </summary>
-    internal class NetGraphOverlay : Overlay
+    internal sealed class NetGraphOverlay : Overlay
     {
         [Dependency] private readonly IGameTiming _gameTiming = default!;
         [Dependency] private readonly IClientNetManager _netManager = default!;
@@ -239,7 +239,7 @@ namespace Robust.Client.GameStates
             base.DisposeBehavior();
         }
 
-        private class NetShowGraphCommand : IConsoleCommand
+        private sealed class NetShowGraphCommand : IConsoleCommand
         {
             public string Command => "net_graph";
             public string Help => "net_graph <0|1>";
@@ -275,7 +275,7 @@ namespace Robust.Client.GameStates
             }
         }
 
-        private class NetWatchEntCommand : IConsoleCommand
+        private sealed class NetWatchEntCommand : IConsoleCommand
         {
             public string Command => "net_watchent";
             public string Help => "net_watchent <0|EntityUid>";

Robust.Client/GameStates/NetInterpOverlay.cs

@@ -11,7 +11,7 @@ using Robust.Shared.Timing;
 
 namespace Robust.Client.GameStates
 {
-    internal class NetInterpOverlay : Overlay
+    internal sealed class NetInterpOverlay : Overlay
     {
         [Dependency] private readonly IEntityManager _entityManager = default!;
         [Dependency] private readonly IEyeManager _eyeManager = default!;
@@ -38,7 +38,7 @@ namespace Robust.Client.GameStates
                 var transform = _entityManager.GetComponent<TransformComponent>(boundingBox.Owner);
 
                 // if not on the same map, continue
-                if (transform.MapID != _eyeManager.CurrentMap || boundingBox.Owner.IsInContainer())
+                if (transform.MapID != _eyeManager.CurrentMap || boundingBox.Owner.IsInContainer(_entityManager))
                     continue;
 
                 // This entity isn't lerping, no need to draw debug info for it
@@ -65,7 +65,7 @@ namespace Robust.Client.GameStates
             }
         }
 
-        private class NetShowInterpCommand : IConsoleCommand
+        private sealed class NetShowInterpCommand : IConsoleCommand
         {
             public string Command => "net_draw_interp";
             public string Help => "net_draw_interp <0|1>";

Robust.Client/Graphics/Audio/ClydeAudio.cs

@@ -18,7 +18,7 @@ using Vector2 = Robust.Shared.Maths.Vector2;
 
 namespace Robust.Client.Graphics.Audio
 {
-    internal partial class ClydeAudio : IClydeAudio, IClydeAudioInternal
+    internal sealed partial class ClydeAudio : IClydeAudio, IClydeAudioInternal
     {
         private ALDevice _openALDevice;
         private ALContext _openALContext;
@@ -224,7 +224,7 @@ namespace Robust.Client.Graphics.Audio
                 _openALSawmill.Error("Failed to generate source. Too many simultaneous audio streams?");
                 return null;
             }
-            
+
             // ReSharper disable once PossibleInvalidOperationException
             // TODO: This really shouldn't be indexing based on the ClydeHandle...
             AL.Source(source, ALSourcei.Buffer, _audioSampleBuffers[(int) stream.ClydeHandle!.Value.Value].BufferHandle);

Robust.Client/Graphics/Audio/DummyAudioSource.cs

@@ -18,6 +18,7 @@ namespace Robust.Client.Graphics.Audio
     /// <summary>
     ///     Hey look, it's ClydeAudio.AudioSource's evil twin brother!
     /// </summary>
+    [Virtual]
     internal class DummyAudioSource : IClydeAudioSource
     {
         public static DummyAudioSource Instance { get; } = new();

Robust.Client/Graphics/ClientEye/Eye.cs

@@ -7,6 +7,7 @@ using Robust.Shared.ViewVariables;
 namespace Robust.Client.Graphics
 {
     /// <inheritdoc />
+    [Virtual]
     public class Eye : IEye
     {
         private Vector2 _scale = Vector2.One/2f;

Robust.Client/Graphics/ClientEye/EyeManager.cs

@@ -153,7 +153,7 @@ namespace Robust.Client.Graphics
         }
     }
 
-    public class CurrentEyeChangedEvent : EntityEventArgs
+    public sealed class CurrentEyeChangedEvent : EntityEventArgs
     {
         public IEye? Old { get; }
         public IEye New { get; }

Robust.Client/Graphics/ClientEye/FixedEye.cs

@@ -3,7 +3,7 @@
     /// <summary>
     ///     A fixed eye is an eye which is fixed to one point, its position.
     /// </summary>
-    public class FixedEye : Eye
+    public sealed class FixedEye : Eye
     {
     }
 }

Robust.Client/Graphics/Clyde/Clyde.GridRendering.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Buffers;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -214,7 +214,7 @@ namespace Robust.Client.Graphics.Clyde
             _mapChunkData.Remove(gridId);
         }
 
-        private class MapChunkData
+        private sealed class MapChunkData
         {
             public bool Dirty;
             public readonly uint VAO;

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

@@ -372,22 +372,24 @@ namespace Robust.Client.Graphics.Clyde
         private void ProcessSpriteEntities(MapId map, Matrix3 eyeMatrix, Box2Rotated worldBounds,
             RefList<(SpriteComponent sprite, Matrix3 matrix, Angle worldRot, float yWorldPos)> list)
         {
+            var xforms = _entityManager.GetEntityQuery<TransformComponent>();
+
             foreach (var comp in _entitySystemManager.GetEntitySystem<RenderingTreeSystem>().GetRenderTrees(map, worldBounds))
             {
-                var bounds = _entityManager.GetComponent<TransformComponent>(comp.Owner).InvWorldMatrix.TransformBox(worldBounds);
+                var bounds = xforms.GetComponent(comp.Owner).InvWorldMatrix.TransformBox(worldBounds);
 
                 comp.SpriteTree.QueryAabb(ref list, (
                     ref RefList<(SpriteComponent sprite, Matrix3 matrix, Angle worldRot, float yWorldPos)> state,
                     in SpriteComponent value) =>
                 {
                     var entity = value.Owner;
-                    var transform = _entityManager.GetComponent<TransformComponent>(entity);
+                    var transform = xforms.GetComponent(entity);
 
                     ref var entry = ref state.AllocAdd();
                     entry.sprite = value;
-                    entry.worldRot = transform.WorldRotation;
-                    entry.matrix = transform.WorldMatrix;
-                    var eyePos = eyeMatrix.Transform(new Vector2(entry.matrix.R0C2, entry.matrix.R1C2));
+                    Vector2 worldPos;
+                    (worldPos, entry.worldRot, entry.matrix) = transform.GetWorldPositionRotationMatrix();
+                    var eyePos = eyeMatrix.Transform(worldPos);
                     // Didn't use the bounds from the query as that has to be re-calculated (and is probably more expensive than this).
                     var bounds = value.CalculateBoundingBox(eyePos);
                     entry.yWorldPos = eyePos.Y - bounds.Extents.Y;

Robust.Client/Graphics/Clyde/Clyde.Helpers.cs

@@ -62,7 +62,7 @@ namespace Robust.Client.Graphics.Clyde
                 PixelInternalFormat.Srgb8Alpha8 => 4,
                 PixelInternalFormat.R11fG11fB10f => 4,
                 PixelInternalFormat.R32f => 4,
-                PixelInternalFormat.Rg32f => 4,
+                PixelInternalFormat.Rg32f => 8,
                 PixelInternalFormat.R8 => 1,
                 _ => 0
             };

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

@@ -515,10 +515,11 @@ namespace Robust.Client.Graphics.Clyde
 
             // Use worldbounds for this one as we only care if the light intersects our actual bounds
             var state = (this, worldAABB, count: 0);
+            var xforms = _entityManager.GetEntityQuery<TransformComponent>();
 
             foreach (var comp in renderingTreeSystem.GetRenderTrees(map, enlargedBounds))
             {
-                var bounds = _entityManager.GetComponent<TransformComponent>(comp.Owner).InvWorldMatrix.TransformBox(worldBounds);
+                var bounds = xforms.GetComponent(comp.Owner).InvWorldMatrix.TransformBox(worldBounds);
 
                 comp.LightTree.QueryAabb(ref state, (ref (Clyde clyde, Box2 worldAABB, int count) state, in PointLightComponent light) =>
                 {
@@ -528,7 +529,7 @@ namespace Robust.Client.Graphics.Clyde
                         return false;
                     }
 
-                    var transform = _entityManager.GetComponent<TransformComponent>(light.Owner);
+                    var transform = xforms.GetComponent(light.Owner);
 
                     if (float.IsNaN(transform.LocalPosition.X) || float.IsNaN(transform.LocalPosition.Y)) return true;
 
@@ -871,21 +872,24 @@ namespace Robust.Client.Graphics.Clyde
                 var ii = 0;
                 var imi = 0;
 
+                var xforms = _entityManager.GetEntityQuery<TransformComponent>();
+
                 foreach (var comp in occluderSystem.GetOccluderTrees(map, expandedBounds))
                 {
-                    var treeBounds = _entityManager.GetComponent<TransformComponent>(comp.Owner).InvWorldMatrix.TransformBox(expandedBounds);
+                    var treeBounds = xforms.GetComponent(comp.Owner).InvWorldMatrix.TransformBox(expandedBounds);
 
                     comp.Tree.QueryAabb((in OccluderComponent sOccluder) =>
                     {
-                        var occluder = (ClientOccluderComponent)sOccluder;
-                        var transform = _entityManager.GetComponent<TransformComponent>(occluder.Owner);
-                        if (!occluder.Enabled)
+                        var transform = xforms.GetComponent(sOccluder.Owner);
+                        if (!sOccluder.Enabled)
                         {
                             return true;
                         }
 
+                        var occluder = (ClientOccluderComponent)sOccluder;
+
                         var worldTransform = transform.WorldMatrix;
-                        var box = occluder.BoundingBox;
+                        var box = sOccluder.BoundingBox;
 
                         var tl = worldTransform.Transform(box.TopLeft);
                         var tr = worldTransform.Transform(box.TopRight);

Robust.Client/Graphics/Clyde/Clyde.Shaders.cs

@@ -34,7 +34,7 @@ namespace Robust.Client.Graphics.Clyde
 
         private readonly ConcurrentQueue<ClydeHandle> _deadShaderInstances = new();
 
-        private class LoadedShader
+        private sealed class LoadedShader
         {
             public GLShaderProgram Program = default!;
             public bool HasLighting = true;
@@ -42,7 +42,7 @@ namespace Robust.Client.Graphics.Clyde
             public string? Name;
         }
 
-        private class LoadedShaderInstance
+        private sealed class LoadedShaderInstance
         {
             public ClydeHandle ShaderHandle;
 

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

@@ -144,7 +144,7 @@ namespace Robust.Client.Graphics.Clyde
                 if (Eye == null)
                     return default;
 
-                var eye = (IEye) Eye;
+                var eye = Eye;
                 var newPoint = point;
 
                 eye.GetViewMatrix(out var viewMatrix, RenderScale);

Robust.Client/Graphics/Clyde/ClydeHeadless.cs

@@ -246,7 +246,7 @@ namespace Robust.Client.Graphics.Clyde
             // Nada.
         }
 
-        private class DummyCursor : ICursor
+        private sealed class DummyCursor : ICursor
         {
             public void Dispose()
             {
@@ -254,6 +254,7 @@ namespace Robust.Client.Graphics.Clyde
             }
         }
 
+        [Virtual]
         private class DummyAudioSource : IClydeAudioSource
         {
             public static DummyAudioSource Instance { get; } = new();

Robust.Client/Graphics/Clyde/GLObjects/Clyde.Buffer.cs

@@ -11,6 +11,7 @@ namespace Robust.Client.Graphics.Clyde
         /// <summary>
         ///     Represents an OpenGL buffer object.
         /// </summary>
+        [Virtual]
         private class GLBuffer
         {
             private readonly Clyde _clyde;
@@ -178,7 +179,7 @@ namespace Robust.Client.Graphics.Clyde
         ///     Subtype of buffers so that we can have a generic constructor.
         ///     Functionally equivalent to <see cref="GLBuffer"/> otherwise.
         /// </summary>
-        private class GLBuffer<T> : GLBuffer where T : unmanaged
+        private sealed class GLBuffer<T> : GLBuffer where T : unmanaged
         {
             public GLBuffer(Clyde clyde, BufferTarget type, BufferUsageHint usage, Span<T> initialize,
                 string? name = null)

Robust.Client/Graphics/Clyde/GLObjects/Clyde.Shader.cs

@@ -4,7 +4,7 @@ namespace Robust.Client.Graphics.Clyde
 {
     internal partial class Clyde
     {
-        private class GLShader
+        private sealed class GLShader
         {
             private readonly Clyde _clyde;
 

Robust.Client/Graphics/Clyde/GLObjects/Clyde.ShaderProgram.cs

@@ -14,7 +14,7 @@ namespace Robust.Client.Graphics.Clyde
         ///     You've been warned:
         ///     using things like <see cref="SetUniformTexture" /> if this buffer isn't bound WILL mess things up!
         /// </summary>
-        private class GLShaderProgram
+        private sealed class GLShaderProgram
         {
             private readonly sbyte?[] _uniformIntCache = new sbyte?[UniCount];
             private readonly Dictionary<string, int> _uniformCache = new();

Robust.Client/Graphics/Clyde/GLObjects/Clyde.UniformBuffer.cs

@@ -20,7 +20,7 @@ namespace Robust.Client.Graphics.Clyde
         /// <summary>
         ///     Represents some set of uniforms that can be backed by a uniform buffer or by regular uniforms.
         /// </summary>
-        private class GLUniformBuffer<T> where T : unmanaged, IAppliableUniformSet
+        private sealed class GLUniformBuffer<T> where T : unmanaged, IAppliableUniformSet
         {
             private readonly Clyde _clyde;
             private readonly int _index;

Robust.Client/Graphics/Clyde/ShaderCompilationException.cs

@@ -6,6 +6,7 @@ namespace Robust.Client.Graphics.Clyde
 {
     [Serializable]
     [PublicAPI]
+    [Virtual]
     internal class ShaderCompilationException : Exception
     {
         public ShaderCompilationException()

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

@@ -104,6 +104,7 @@ namespace Robust.Client.Graphics.Clyde
             }
 
             [Serializable]
+            [Virtual]
             public class GlfwException : Exception
             {
                 public GlfwException()

Robust.Client/Graphics/Drawing/StyleBoxEmpty.cs

@@ -2,7 +2,7 @@ using Robust.Shared.Maths;
 
 namespace Robust.Client.Graphics
 {
-    public class StyleBoxEmpty : StyleBox
+    public sealed class StyleBoxEmpty : StyleBox
     {
         protected override void DoDraw(DrawingHandleScreen handle, UIBox2 box)
         {

Robust.Client/Graphics/Drawing/StyleBoxFlat.cs

@@ -3,7 +3,7 @@ using Robust.Shared.Maths;
 
 namespace Robust.Client.Graphics
 {
-    public class StyleBoxFlat : StyleBox
+    public sealed class StyleBoxFlat : StyleBox
     {
         public Color BackgroundColor { get; set; }
         public Color BorderColor { get; set; }

Robust.Client/Graphics/Drawing/StyleBoxTexture.cs

@@ -7,7 +7,7 @@ namespace Robust.Client.Graphics
     /// <summary>
     ///     Style box based on a 9-patch texture.
     /// </summary>
-    public class StyleBoxTexture : StyleBox
+    public sealed class StyleBoxTexture : StyleBox
     {
         public StyleBoxTexture()
         {

Robust.Client/Graphics/FontManager.cs

@@ -219,7 +219,7 @@ namespace Robust.Client.Graphics
             return bitmapImage;
         }
 
-        private class FontFaceHandle : IFontFaceHandle
+        private sealed class FontFaceHandle : IFontFaceHandle
         {
             public Face Face { get; }
 
@@ -230,7 +230,7 @@ namespace Robust.Client.Graphics
         }
 
         [PublicAPI]
-        private class FontInstanceHandle : IFontInstanceHandle
+        private sealed class FontInstanceHandle : IFontInstanceHandle
         {
             public FontFaceHandle FaceHandle { get; }
             public int Size { get; }
@@ -325,7 +325,7 @@ namespace Robust.Client.Graphics
             }
         }
 
-        private class ScaledFontData
+        private sealed class ScaledFontData
         {
             public ScaledFontData(int ascent, int descent, int height, int lineHeight)
             {

Robust.Client/Graphics/Overlays/OverlayManager.cs

@@ -6,7 +6,7 @@ using Robust.Shared.Timing;
 
 namespace Robust.Client.Graphics
 {
-    internal class OverlayManager : IOverlayManagerInternal
+    internal sealed class OverlayManager : IOverlayManagerInternal
     {
         private readonly Dictionary<Type, Overlay> _overlays = new Dictionary<Type, Overlay>();
         public IEnumerable<Overlay> AllOverlays => _overlays.Values;

Robust.Client/Graphics/Shaders/ShaderPrototype.cs

@@ -192,7 +192,7 @@ namespace Robust.Client.Graphics
         }
 
         [DataDefinition]
-        public class StencilData
+        public sealed class StencilData
         {
             [DataField("ref")] public int StencilRef;
 

Robust.Client/Input/Events.cs

@@ -53,6 +53,7 @@ namespace Robust.Client.Input
         }
     }
 
+    [Virtual]
     public class TextEventArgs : EventArgs
     {
         public TextEventArgs(uint codePoint)
@@ -64,6 +65,7 @@ namespace Robust.Client.Input
         public Rune AsRune => new Rune(CodePoint);
     }
 
+    [Virtual]
     public class KeyEventArgs : ModifierInputEventArgs
     {
         /// <summary>
@@ -104,7 +106,7 @@ namespace Robust.Client.Input
         }
     }
 
-    public class MouseButtonEventArgs : MouseEventArgs
+    public sealed  class MouseButtonEventArgs : MouseEventArgs
     {
         /// <summary>
         ///     The mouse button that has been pressed or released.
@@ -119,7 +121,7 @@ namespace Robust.Client.Input
         }
     }
 
-    public class MouseWheelEventArgs : MouseEventArgs
+    public sealed class MouseWheelEventArgs : MouseEventArgs
     {
         /// <summary>
         ///     The direction the mouse wheel was moved in.
@@ -134,7 +136,7 @@ namespace Robust.Client.Input
         }
     }
 
-    public class MouseMoveEventArgs : MouseEventArgs
+    public sealed class MouseMoveEventArgs : MouseEventArgs
     {
         /// <summary>
         ///     The new position relative to the previous position.
@@ -149,7 +151,7 @@ namespace Robust.Client.Input
         }
     }
 
-    public class MouseEnterLeaveEventArgs : EventArgs
+    public sealed class MouseEnterLeaveEventArgs : EventArgs
     {
         public IClydeWindow Window { get; }
 

Robust.Client/Input/InputManager.cs

@@ -31,6 +31,7 @@ using static Robust.Client.Input.Keyboard;
 
 namespace Robust.Client.Input
 {
+    [Virtual]
     internal class InputManager : IInputManager
     {
         // This is for both userdata and resources.
@@ -698,7 +699,7 @@ namespace Robust.Client.Input
         }
 
         [DebuggerDisplay("KeyBinding {" + nameof(Function) + "}")]
-        private class KeyBinding : IKeyBinding
+        private sealed class KeyBinding : IKeyBinding
         {
             private readonly InputManager _inputManager;
 
@@ -906,7 +907,7 @@ namespace Robust.Client.Input
     }
 
     [UsedImplicitly]
-    internal class BindCommand : IConsoleCommand
+    internal sealed class BindCommand : IConsoleCommand
     {
         public string Command => "bind";
         public string Description => "Binds an input key to an input command.";
@@ -960,7 +961,7 @@ namespace Robust.Client.Input
     }
 
     [UsedImplicitly]
-    internal class SaveBindCommand : IConsoleCommand
+    internal sealed class SaveBindCommand : IConsoleCommand
     {
         public string Command => "svbind";
         public string Description => "";

Robust.Client/Input/KeyBindingRegistration.cs

@@ -4,7 +4,7 @@ using Robust.Shared.Serialization.Manager.Attributes;
 namespace Robust.Client.Input
 {
     [DataDefinition]
-    public class KeyBindingRegistration
+    public sealed class KeyBindingRegistration
     {
         [DataField("function")]
         public BoundKeyFunction Function;