Version: 0.14.1.1

* huh it works.

* vector arrays

.gitmodules

@@ -10,9 +10,6 @@
 [submodule "Robust.LoaderApi"]
 	path = Robust.LoaderApi
 	url = https://github.com/space-wizards/Robust.LoaderApi.git
-[submodule "ManagedHttpListener"]
-	path = ManagedHttpListener
-	url = https://github.com/space-wizards/ManagedHttpListener.git
 [submodule "cefglue"]
 	path = cefglue
 	url = https://github.com/space-wizards/cefglue.git

MSBuild/Robust.Engine.Version.props

@@ -1,4 +1,4 @@
 <Project>
     <!-- This file automatically reset by Tools/version.py -->
-    <PropertyGroup><Version>0.8.86</Version></PropertyGroup>
+    <PropertyGroup><Version>0.14.1.1</Version></PropertyGroup>
 </Project>

Resources/Locale/en-US/controls.ftl

@@ -0,0 +1,10 @@
+color-selector-sliders-red = R
+color-selector-sliders-green = G
+color-selector-sliders-blue = B
+color-selector-sliders-hue = H
+color-selector-sliders-saturation = S
+color-selector-sliders-value = V
+color-selector-sliders-alpha = A
+
+color-selector-sliders-rgb = RGB
+color-selector-sliders-hsv = HSV

Resources/Locale/en-US/midi-commands.ftl

@@ -0,0 +1 @@
+midi-panic-command-description = Turns off every note for every active MIDI renderer.

Robust.Benchmarks/Serialization/BenchmarkIntSerializer.cs

@@ -1,7 +1,6 @@
 using System.Globalization;
 using Robust.Shared.IoC;
 using Robust.Shared.Serialization.Manager;
-using Robust.Shared.Serialization.Manager.Result;
 using Robust.Shared.Serialization.Markdown;
 using Robust.Shared.Serialization.Markdown.Validation;
 using Robust.Shared.Serialization.Markdown.Value;
@@ -19,10 +18,10 @@ namespace Robust.Benchmarks.Serialization
                 : new ErrorNode(node, $"Failed parsing int value: {node.Value}");
         }
 
-        public DeserializationResult Read(ISerializationManager serializationManager, ValueDataNode node,
-            IDependencyCollection dependencies, bool skipHook, ISerializationContext? context = null)
+        public int Read(ISerializationManager serializationManager, ValueDataNode node,
+            IDependencyCollection dependencies, bool skipHook, ISerializationContext? context = null, int _ = default)
         {
-            return new DeserializedValue<int>(int.Parse(node.Value, CultureInfo.InvariantCulture));
+            return int.Parse(node.Value, CultureInfo.InvariantCulture);
         }
 
         public DataNode Write(ISerializationManager serializationManager, int value, bool alwaysWrite = false,

Robust.Benchmarks/Serialization/Copy/SerializationCopyBenchmark.cs

@@ -28,7 +28,7 @@ namespace Robust.Benchmarks.Serialization.Copy
 
             var seedMapping = yamlStream.Documents[0].RootNode.ToDataNodeCast<SequenceDataNode>().Cast<MappingDataNode>(0);
 
-            Seed = SerializationManager.ReadValueOrThrow<SeedDataDefinition>(seedMapping);
+            Seed = SerializationManager.Read<SeedDataDefinition>(seedMapping);
         }
 
         private const string String = "ABC";

Robust.Benchmarks/Serialization/Definitions/SeedDataDefinition.cs

@@ -36,7 +36,7 @@ namespace Robust.Benchmarks.Serialization.Definitions
       Max: 10
       PotencyDivisor: 10";
 
-        [DataField("id", required: true)] public string ID { get; set; } = default!;
+        [IdDataFieldAttribute] public string ID { get; set; } = default!;
 
         #region Tracking
         [DataField("name")] public string Name { get; set; } = string.Empty;

Robust.Benchmarks/Serialization/Read/SerializationReadBenchmark.cs

@@ -2,7 +2,6 @@
 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;
 using Robust.Shared.Serialization.Markdown.Sequence;
@@ -42,32 +41,32 @@ namespace Robust.Benchmarks.Serialization.Read
         private ValueDataNode FlagThirtyOne { get; } = new("ThirtyOne");
 
         [Benchmark]
-        public string? ReadString()
+        public string ReadString()
         {
-            return SerializationManager.ReadValue<string>(StringNode);
+            return SerializationManager.Read<string>(StringNode);
         }
 
         [Benchmark]
-        public int? ReadInteger()
+        public int ReadInteger()
         {
-            return SerializationManager.ReadValue<int>(IntNode);
+            return SerializationManager.Read<int>(IntNode);
         }
 
         [Benchmark]
-        public DataDefinitionWithString? ReadDataDefinitionWithString()
+        public DataDefinitionWithString ReadDataDefinitionWithString()
         {
-            return SerializationManager.ReadValue<DataDefinitionWithString>(StringDataDefNode);
+            return SerializationManager.Read<DataDefinitionWithString>(StringDataDefNode);
         }
 
         [Benchmark]
-        public SeedDataDefinition? ReadSeedDataDefinition()
+        public SeedDataDefinition ReadSeedDataDefinition()
         {
-            return SerializationManager.ReadValue<SeedDataDefinition>(SeedNode);
+            return SerializationManager.Read<SeedDataDefinition>(SeedNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("flag")]
-        public DeserializationResult ReadFlagZero()
+        public object? ReadFlagZero()
         {
             return SerializationManager.ReadWithTypeSerializer(
                 typeof(int),
@@ -77,7 +76,7 @@ namespace Robust.Benchmarks.Serialization.Read
 
         [Benchmark]
         [BenchmarkCategory("flag")]
-        public DeserializationResult ReadThirtyOne()
+        public object? ReadThirtyOne()
         {
             return SerializationManager.ReadWithTypeSerializer(
                 typeof(int),
@@ -87,7 +86,7 @@ namespace Robust.Benchmarks.Serialization.Read
 
         [Benchmark]
         [BenchmarkCategory("customTypeSerializer")]
-        public DeserializationResult ReadIntegerCustomSerializer()
+        public object? ReadIntegerCustomSerializer()
         {
             return SerializationManager.ReadWithTypeSerializer(
                 typeof(int),

Robust.Benchmarks/Serialization/SerializationArrayBenchmark.cs

@@ -46,84 +46,84 @@ namespace Robust.Benchmarks.Serialization
         [BenchmarkCategory("read")]
         public string[]? ReadEmptyString()
         {
-            return SerializationManager.ReadValue<string[]>(EmptyNode);
+            return SerializationManager.Read<string[]>(EmptyNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public string[]? ReadOneString()
         {
-            return SerializationManager.ReadValue<string[]>(OneIntNode);
+            return SerializationManager.Read<string[]>(OneIntNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public string[]? ReadTenStrings()
         {
-            return SerializationManager.ReadValue<string[]>(TenIntsNode);
+            return SerializationManager.Read<string[]>(TenIntsNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public int[]? ReadEmptyInt()
         {
-            return SerializationManager.ReadValue<int[]>(EmptyNode);
+            return SerializationManager.Read<int[]>(EmptyNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public int[]? ReadOneInt()
         {
-            return SerializationManager.ReadValue<int[]>(OneIntNode);
+            return SerializationManager.Read<int[]>(OneIntNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public int[]? ReadTenInts()
         {
-            return SerializationManager.ReadValue<int[]>(TenIntsNode);
+            return SerializationManager.Read<int[]>(TenIntsNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public DataDefinitionWithString[]? ReadEmptyStringDataDef()
         {
-            return SerializationManager.ReadValue<DataDefinitionWithString[]>(EmptyNode);
+            return SerializationManager.Read<DataDefinitionWithString[]>(EmptyNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public DataDefinitionWithString[]? ReadOneStringDataDef()
         {
-            return SerializationManager.ReadValue<DataDefinitionWithString[]>(OneStringDefNode);
+            return SerializationManager.Read<DataDefinitionWithString[]>(OneStringDefNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public DataDefinitionWithString[]? ReadTenStringDataDefs()
         {
-            return SerializationManager.ReadValue<DataDefinitionWithString[]>(TenStringDefsNode);
+            return SerializationManager.Read<DataDefinitionWithString[]>(TenStringDefsNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public SealedDataDefinitionWithString[]? ReadEmptySealedStringDataDef()
         {
-            return SerializationManager.ReadValue<SealedDataDefinitionWithString[]>(EmptyNode);
+            return SerializationManager.Read<SealedDataDefinitionWithString[]>(EmptyNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public SealedDataDefinitionWithString[]? ReadOneSealedStringDataDef()
         {
-            return SerializationManager.ReadValue<SealedDataDefinitionWithString[]>(OneStringDefNode);
+            return SerializationManager.Read<SealedDataDefinitionWithString[]>(OneStringDefNode);
         }
 
         [Benchmark]
         [BenchmarkCategory("read")]
         public SealedDataDefinitionWithString[]? ReadTenSealedStringDataDefs()
         {
-            return SerializationManager.ReadValue<SealedDataDefinitionWithString[]>(TenStringDefsNode);
+            return SerializationManager.Read<SealedDataDefinitionWithString[]>(TenStringDefsNode);
         }
     }
 }

Robust.Benchmarks/Serialization/Write/SerializationWriteBenchmark.cs

@@ -28,7 +28,7 @@ namespace Robust.Benchmarks.Serialization.Write
 
             var seedMapping = yamlStream.Documents[0].RootNode.ToDataNodeCast<SequenceDataNode>().Cast<MappingDataNode>(0);
 
-            Seed = SerializationManager.ReadValueOrThrow<SeedDataDefinition>(seedMapping);
+            Seed = SerializationManager.Read<SeedDataDefinition>(seedMapping);
         }
 
         private const string String = "ABC";

Robust.Client/Audio/Midi/Commands/MidiPanicCommand.cs

@@ -0,0 +1,22 @@
+using Robust.Shared.Console;
+using Robust.Shared.IoC;
+using Robust.Shared.Localization;
+
+namespace Robust.Client.Audio.Midi.Commands;
+
+public sealed class MidiPanicCommand : IConsoleCommand
+{
+    [Dependency] private readonly IMidiManager _midiManager = default!;
+
+    public string Command => "midipanic";
+    public string Description => Loc.GetString("midi-panic-command-description");
+    public string Help => $"{Command}";
+
+    public void Execute(IConsoleShell shell, string argStr, string[] args)
+    {
+        foreach (var renderer in _midiManager.Renderers)
+        {
+            renderer.StopAllNotes();
+        }
+    }
+}

Robust.Client/Audio/Midi/IMidiManager.cs

@@ -0,0 +1,62 @@
+using System.Collections.Generic;
+using NFluidsynth;
+using Robust.Shared.Audio.Midi;
+
+namespace Robust.Client.Audio.Midi;
+
+public interface IMidiManager
+{
+    /// <summary>
+    ///     A read-only list of all existing MIDI Renderers.
+    /// </summary>
+    IReadOnlyList<IMidiRenderer> Renderers { get; }
+
+    /// <summary>
+    ///     If true, MIDI support is available.
+    /// </summary>
+    bool IsAvailable { get; }
+
+    /// <summary>
+    ///     Volume, in db.
+    /// </summary>
+    float Volume { get; set; }
+
+    public int OcclusionCollisionMask { get; set; }
+
+    /// <summary>
+    ///     This method tries to return a midi renderer ready to be used.
+    ///     You only need to set the <see cref="IMidiRenderer.MidiProgram"/> afterwards.
+    /// </summary>
+    /// <remarks>
+    ///     This method can fail if MIDI support is not available.
+    /// </remarks>
+    /// <returns>
+    ///     <c>null</c> if MIDI support is not available.
+    /// </returns>
+    IMidiRenderer? GetNewRenderer(bool mono = true);
+
+    /// <summary>
+    ///     Creates a <see cref="RobustMidiEvent"/> given a <see cref="MidiEvent"/> and a sequencer tick.
+    /// </summary>
+    RobustMidiEvent FromFluidEvent(MidiEvent midiEvent, uint tick);
+
+    /// <summary>
+    ///     Creates a <see cref="SequencerEvent"/> given a <see cref="RobustMidiEvent"/>.
+    ///     Be sure to dispose of the result after you've used it.
+    /// </summary>
+    SequencerEvent ToSequencerEvent(RobustMidiEvent midiEvent);
+
+    /// <summary>
+    ///     Creates a <see cref="RobustMidiEvent"/> given a <see cref="SequencerEvent"/> and a sequencer tick.
+    /// </summary>
+    RobustMidiEvent FromSequencerEvent(SequencerEvent midiEvent, uint tick);
+
+    /// <summary>
+    ///     Method called every frame.
+    ///     Should be used to update positional audio.
+    /// </summary>
+    /// <param name="frameTime"></param>
+    void FrameUpdate(float frameTime);
+
+    void Shutdown();
+}

Robust.Client/Audio/Midi/IMidiRenderer.cs

@@ -0,0 +1,174 @@
+using System;
+using Robust.Client.Graphics;
+using Robust.Shared.Audio.Midi;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Map;
+
+namespace Robust.Client.Audio.Midi;
+
+public enum MidiRendererStatus : byte
+{
+    None,
+    Input,
+    File,
+}
+
+public interface IMidiRenderer : IDisposable
+{
+
+    /// <summary>
+    ///     The buffered audio source of this renderer.
+    /// </summary>
+    internal IClydeBufferedAudioSource Source { get; }
+
+    /// <summary>
+    ///     Whether this renderer has been disposed or not.
+    /// </summary>
+    bool Disposed { get; }
+
+    /// <summary>
+    ///     This controls whether the midi file being played will loop or not.
+    /// </summary>
+    bool LoopMidi { get; set; }
+
+    /// <summary>
+    ///     This increases all note on velocities to 127.
+    /// </summary>
+    bool VolumeBoost { get; set; }
+
+    /// <summary>
+    ///     The midi program (instrument) the renderer is using.
+    /// </summary>
+    byte MidiProgram { get; set; }
+
+    /// <summary>
+    ///     The instrument bank the renderer is using.
+    /// </summary>
+    byte MidiBank { get; set; }
+
+    /// <summary>
+    ///     The soundfont currently selected by the renderer.
+    /// </summary>
+    uint MidiSoundfont { get; set; }
+
+    /// <summary>
+    ///     The current status of the renderer.
+    ///     "None" if the renderer isn't playing from input or a midi file.
+    ///     "Input" if the renderer is playing from midi input.
+    ///     "File" if the renderer is playing from a midi file.
+    /// </summary>
+    MidiRendererStatus Status { get; }
+
+    /// <summary>
+    ///     Whether the sound will play in stereo or mono.
+    /// </summary>
+    bool Mono { get; set; }
+
+    /// <summary>
+    ///     Whether to drop messages on the percussion channel.
+    /// </summary>
+    bool DisablePercussionChannel { get; set; }
+
+    /// <summary>
+    /// Whether to drop messages for program change events.
+    /// </summary>
+    bool DisableProgramChangeEvent { get; set; }
+
+    /// <summary>
+    ///     Gets the total number of ticks possible for the MIDI player.
+    /// </summary>
+    int PlayerTotalTick { get; }
+
+    /// <summary>
+    ///     Gets or sets (seeks) the current tick of the MIDI player.
+    /// </summary>
+    int PlayerTick { get; set; }
+
+    /// <summary>
+    ///     Gets the current tick of the sequencer.
+    /// </summary>
+    uint SequencerTick { get; }
+
+    /// <summary>
+    ///     Gets the Time Scale of the sequencer in ticks per second. Default is 1000 for 1 tick per millisecond.
+    /// </summary>
+    double SequencerTimeScale { get; }
+
+    /// <summary>
+    ///     Start listening for midi input.
+    /// </summary>
+    bool OpenInput();
+
+    /// <summary>
+    ///     Start playing a midi file.
+    /// </summary>
+    /// <param name="buffer">Bytes of the midi file</param>
+    bool OpenMidi(ReadOnlySpan<byte> buffer);
+
+    /// <summary>
+    ///     Stops listening for midi input.
+    /// </summary>
+    bool CloseInput();
+
+    /// <summary>
+    ///     Stops playing midi files.
+    /// </summary>
+    bool CloseMidi();
+
+    /// <summary>
+    ///     Stops all notes being played currently.
+    /// </summary>
+    void StopAllNotes();
+
+    /// <summary>
+    ///     Render and play MIDI to the audio source.
+    /// </summary>
+    internal void Render();
+
+    /// <summary>
+    ///     Loads a new soundfont into the renderer.
+    /// </summary>
+    void LoadSoundfont(string filename, bool resetPresets = false);
+
+    /// <summary>
+    ///     Invoked whenever a new midi event is registered.
+    /// </summary>
+    event Action<RobustMidiEvent> OnMidiEvent;
+
+    /// <summary>
+    ///     Invoked when the midi player finishes playing a song.
+    /// </summary>
+    event Action OnMidiPlayerFinished;
+
+    /// <summary>
+    ///     The entity whose position will be used for positional audio.
+    ///     This is only used if <see cref="Mono"/> is set to True.
+    /// </summary>
+    EntityUid? TrackingEntity { get; set; }
+
+    /// <summary>
+    ///     The position that will be used for positional audio.
+    ///     This is only used if <see cref="Mono"/> is set to True
+    ///     and <see cref="TrackingEntity"/> is null.
+    /// </summary>
+    EntityCoordinates? TrackingCoordinates { get; set; }
+
+    /// <summary>
+    ///     Send a midi event for the renderer to play.
+    /// </summary>
+    /// <param name="midiEvent">The midi event to be played</param>
+    void SendMidiEvent(RobustMidiEvent midiEvent);
+
+    /// <summary>
+    ///     Schedule a MIDI event to be played at a later time.
+    /// </summary>
+    /// <param name="midiEvent">the midi event in question</param>
+    /// <param name="time"></param>
+    /// <param name="absolute"></param>
+    void ScheduleMidiEvent(RobustMidiEvent midiEvent, uint time, bool absolute);
+
+    /// <summary>
+    ///     Actually disposes of this renderer. Do NOT use outside the MIDI thread.
+    /// </summary>
+    internal void InternalDispose();
+}

Robust.Client/Audio/Midi/MidiManager.Conversion.cs

@@ -0,0 +1,155 @@
+using NFluidsynth;
+using Robust.Shared.Audio.Midi;
+
+namespace Robust.Client.Audio.Midi;
+
+internal sealed partial class MidiManager
+{
+    public RobustMidiEvent FromFluidEvent(MidiEvent midiEvent, uint tick)
+    {
+        var status = RobustMidiEvent.MakeStatus((byte) midiEvent.Channel, (byte) midiEvent.Type);
+
+        // Control is always the first data byte. Value is always the second data byte. Fluidsynth's API ain't great.
+        var data1 = (byte) midiEvent.Control;
+        var data2 = (byte) midiEvent.Value;
+
+        // PitchBend is handled specially.
+        if (midiEvent.Type == (int) RobustMidiCommand.PitchBend)
+        {
+            // We pack pitch into both data values.
+            var pitch = (ushort) midiEvent.Pitch;
+            data1 = (byte) pitch;
+            data2 = (byte) (pitch >> 8);
+        }
+
+        return new RobustMidiEvent(status, data1, data2, tick);
+    }
+
+    public SequencerEvent ToSequencerEvent(RobustMidiEvent midiEvent)
+    {
+        var sequencerEvent = new SequencerEvent();
+
+        switch (midiEvent.MidiCommand)
+        {
+            case RobustMidiCommand.NoteOff:
+                sequencerEvent.NoteOff(midiEvent.Channel, midiEvent.Key);
+                break;
+
+            case RobustMidiCommand.NoteOn:
+                sequencerEvent.NoteOn(midiEvent.Channel, midiEvent.Key, midiEvent.Velocity);
+                break;
+
+            case RobustMidiCommand.AfterTouch:
+                sequencerEvent.KeyPressure(midiEvent.Channel, midiEvent.Key, midiEvent.Value);
+                break;
+
+            case RobustMidiCommand.ControlChange:
+                sequencerEvent.ControlChange(midiEvent.Channel, midiEvent.Control, midiEvent.Value);
+                break;
+
+            case RobustMidiCommand.ProgramChange:
+                sequencerEvent.ProgramChange(midiEvent.Channel, midiEvent.Program);
+                break;
+
+            case RobustMidiCommand.ChannelPressure:
+                sequencerEvent.ChannelPressure(midiEvent.Channel, midiEvent.Value);
+                break;
+
+            case RobustMidiCommand.PitchBend:
+                sequencerEvent.PitchBend(midiEvent.Channel, midiEvent.Pitch);
+                break;
+
+            case RobustMidiCommand.SystemMessage:
+                switch (midiEvent.Control)
+                {
+                    case 0x0 when midiEvent.Status == 0xFF:
+                        sequencerEvent.SystemReset();
+                        break;
+
+                    case 0x0B:
+                        sequencerEvent.AllNotesOff(midiEvent.Channel);
+                        break;
+
+                    default:
+                        _midiSawmill.Warning($"Tried to convert unsupported event to sequencer event:\n{midiEvent}");
+                        break;
+                }
+
+                break;
+
+            default:
+                _midiSawmill.Warning($"Tried to convert unsupported event to sequencer event:\n{midiEvent}");
+                break;
+        }
+
+        return sequencerEvent;
+    }
+
+    public RobustMidiEvent FromSequencerEvent(SequencerEvent midiEvent, uint tick)
+    {
+        byte channel = (byte) midiEvent.Channel;
+        RobustMidiCommand command = 0x0;
+        byte data1 = 0;
+        byte data2 = 0;
+
+        switch (midiEvent.Type)
+        {
+            case FluidSequencerEventType.NoteOn:
+                command = RobustMidiCommand.NoteOn;
+                data1 = (byte) midiEvent.Key;
+                data2 = (byte) midiEvent.Velocity;
+                break;
+
+            case FluidSequencerEventType.NoteOff:
+                command = RobustMidiCommand.NoteOff;
+                data1 = (byte) midiEvent.Key;
+                break;
+
+            case FluidSequencerEventType.PitchBend:
+                command = RobustMidiCommand.PitchBend;
+                // We pack pitch into both data values
+                var pitch = (ushort) midiEvent.Pitch;
+                data1 = (byte) pitch;
+                data2 = (byte) (pitch >> 8);
+                break;
+
+            case FluidSequencerEventType.ProgramChange:
+                command = RobustMidiCommand.ProgramChange;
+                data1 = (byte) midiEvent.Program;
+                break;
+
+            case FluidSequencerEventType.KeyPressure:
+                command = RobustMidiCommand.AfterTouch;
+                data1 = (byte) midiEvent.Key;
+                data2 = (byte) midiEvent.Value;
+                break;
+
+            case FluidSequencerEventType.ControlChange:
+                command = RobustMidiCommand.ControlChange;
+                data1 = (byte) midiEvent.Control;
+                data2 = (byte) midiEvent.Value;
+                break;
+
+            case FluidSequencerEventType.ChannelPressure:
+                command = RobustMidiCommand.ChannelPressure;
+                data1 = (byte) midiEvent.Value;
+                break;
+
+            case FluidSequencerEventType.AllNotesOff:
+                command = RobustMidiCommand.SystemMessage;
+                data1 = 0x0B;
+                break;
+
+            case FluidSequencerEventType.SystemReset:
+                command = RobustMidiCommand.SystemMessage;
+                channel = 0x0F;
+                break;
+
+            default:
+                _midiSawmill.Error($"Unsupported Sequencer Event: {tick:D8}: {SequencerEventToString(midiEvent)}");
+                break;
+        }
+
+        return new RobustMidiEvent(RobustMidiEvent.MakeStatus(channel, (byte)command), data1, data2, tick);
+    }
+}

Robust.Client/Audio/Midi/MidiManager.cs

@@ -7,6 +7,7 @@ using NFluidsynth;
 using Robust.Client.Graphics;
 using Robust.Client.ResourceManagement;
 using Robust.Shared;
+using Robust.Shared.Asynchronous;
 using Robust.Shared.Configuration;
 using Robust.Shared.ContentPack;
 using Robust.Shared.GameObjects;
@@ -15,404 +16,435 @@ using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Physics;
-using Robust.Shared.Physics.Broadphase;
 using Robust.Shared.Utility;
 using Robust.Shared.ViewVariables;
-using Logger = Robust.Shared.Log.Logger;
 
-namespace Robust.Client.Audio.Midi
+namespace Robust.Client.Audio.Midi;
+
+internal sealed partial class MidiManager : IMidiManager
 {
-    public interface IMidiManager
+    [Dependency] private readonly IEyeManager _eyeManager = default!;
+    [Dependency] private readonly IResourceManagerInternal _resourceManager = default!;
+    [Dependency] private readonly IEntityManager _entityManager = default!;
+    [Dependency] private readonly IConfigurationManager _cfgMan = default!;
+    [Dependency] private readonly IClydeAudio _clydeAudio = default!;
+    [Dependency] private readonly ITaskManager _taskManager = default!;
+    [Dependency] private readonly ILogManager _logger = default!;
+
+    private SharedPhysicsSystem _broadPhaseSystem = default!;
+
+    public IReadOnlyList<IMidiRenderer> Renderers
     {
-        /// <summary>
-        ///     This method tries to return a midi renderer ready to be used.
-        ///     You only need to set the <see cref="IMidiRenderer.MidiProgram"/> afterwards.
-        /// </summary>
-        /// <remarks>
-        ///     This method can fail if MIDI support is not available.
-        /// </remarks>
-        /// <returns>
-        ///     <c>null</c> if MIDI support is not available.
-        /// </returns>
-        IMidiRenderer? GetNewRenderer();
-
-        /// <summary>
-        ///     Method called every frame.
-        ///     Should be used to update positional audio.
-        /// </summary>
-        /// <param name="frameTime"></param>
-        void FrameUpdate(float frameTime);
-
-        /// <summary>
-        ///     Volume, in db.
-        /// </summary>
-        float Volume { get; set; }
-
-        /// <summary>
-        ///     If true, MIDI support is available.
-        /// </summary>
-        bool IsAvailable { get; }
-
-        public int OcclusionCollisionMask { get; set; }
-
-        void Shutdown();
+        get
+        {
+            lock (_renderers)
+            {
+                // Perform a copy. Sadly, we can't return a reference to the original list due to threading concerns.
+                return _renderers.ToArray();
+            }
+        }
     }
 
-    internal sealed class MidiManager : IMidiManager
+    [ViewVariables]
+    public bool IsAvailable
     {
-        [Dependency] private readonly IEyeManager _eyeManager = default!;
-        [Dependency] private readonly IResourceManagerInternal _resourceManager = default!;
-        [Dependency] private readonly IEntityManager _entityManager = default!;
-        [Dependency] private readonly IConfigurationManager _cfgMan = default!;
-
-        private SharedPhysicsSystem _broadPhaseSystem = default!;
-
-        [ViewVariables]
-        public bool IsAvailable
+        get
         {
-            get
-            {
-                InitializeFluidsynth();
+            InitializeFluidsynth();
 
-                return FluidsynthInitialized;
-            }
+            return FluidsynthInitialized;
+        }
+    }
+
+    [ViewVariables]
+    private readonly List<IMidiRenderer> _renderers = new();
+
+    private bool _alive = true;
+    private Settings? _settings;
+    private Thread? _midiThread;
+    private ISawmill _midiSawmill = default!;
+    private float _volume = 0f;
+    private bool _volumeDirty = true;
+
+    // Not reliable until Fluidsynth is initialized!
+    [ViewVariables(VVAccess.ReadWrite)]
+    public float Volume
+    {
+        get => _volume;
+        set
+        {
+            if (MathHelper.CloseToPercent(_volume, value))
+                return;
+
+            _cfgMan.SetCVar(CVars.MidiVolume, value);
+            _volumeDirty = true;
+        }
+    }
+
+    private static readonly string[] LinuxSoundfonts =
+    {
+        "/usr/share/soundfonts/default.sf2",
+        "/usr/share/soundfonts/FluidR3_GM.sf2",
+        "/usr/share/soundfonts/freepats-general-midi.sf2",
+        "/usr/share/sounds/sf2/default.sf2",
+        "/usr/share/sounds/sf2/FluidR3_GM.sf2",
+        "/usr/share/sounds/sf2/TimGM6mb.sf2",
+    };
+
+    private const string WindowsSoundfont = @"C:\WINDOWS\system32\drivers\gm.dls";
+
+    private const string OsxSoundfont =
+        "/System/Library/Components/CoreAudio.component/Contents/Resources/gs_instruments.dls";
+
+    private const string FallbackSoundfont = "/Midi/fallback.sf2";
+
+    private static ResourcePath CustomSoundfontDirectory = new ResourcePath("/soundfonts/");
+
+    private readonly ResourceLoaderCallbacks _soundfontLoaderCallbacks = new();
+
+    private bool FluidsynthInitialized;
+    private bool _failedInitialize;
+
+    private NFluidsynth.Logger.LoggerDelegate _loggerDelegate = default!;
+    private ISawmill _sawmill = default!;
+
+    [ViewVariables(VVAccess.ReadWrite)]
+    public int OcclusionCollisionMask { get; set; }
+
+    private void InitializeFluidsynth()
+    {
+        if (FluidsynthInitialized || _failedInitialize) return;
+
+        _volume = _cfgMan.GetCVar(CVars.MidiVolume);
+        _cfgMan.OnValueChanged(CVars.MidiVolume, value =>
+        {
+            _volume = value;
+            _volumeDirty = true;
+        }, true);
+
+        _midiSawmill = _logger.GetSawmill("midi");
+        _midiSawmill.Level = LogLevel.Info;
+        _sawmill = _logger.GetSawmill("midi.fluidsynth");
+        _loggerDelegate = LoggerDelegate;
+
+        if (!_resourceManager.UserData.Exists(CustomSoundfontDirectory))
+        {
+            _resourceManager.UserData.CreateDir(CustomSoundfontDirectory);
+        }
+        // not a directory, preserve the old file and create an actual directory
+        else if (!_resourceManager.UserData.IsDir(CustomSoundfontDirectory))
+        {
+            _resourceManager.UserData.Rename(CustomSoundfontDirectory, CustomSoundfontDirectory.WithName(CustomSoundfontDirectory.Filename + ".old"));
+            _resourceManager.UserData.CreateDir(CustomSoundfontDirectory);
         }
 
-        [ViewVariables]
-        private readonly List<IMidiRenderer> _renderers = new();
-
-        private bool _alive = true;
-        private Settings? _settings;
-        private Thread? _midiThread;
-        private ISawmill _midiSawmill = default!;
-        private float _volume = 0f;
-        private bool _volumeDirty = true;
-
-        // Not reliable until Fluidsynth is initialized!
-        [ViewVariables(VVAccess.ReadWrite)]
-        public float Volume
+        try
         {
-            get => _volume;
-            set
-            {
-                if (MathHelper.CloseToPercent(_volume, value))
-                    return;
+            NFluidsynth.Logger.SetLoggerMethod(_loggerDelegate); // Will cause a safe DllNotFoundException if not available.
 
-                _cfgMan.SetCVar(CVars.MidiVolume, value);
-                _volumeDirty = true;
-            }
+            _settings = new Settings();
+            _settings["synth.sample-rate"].DoubleValue = 44100;
+            _settings["player.timing-source"].StringValue = "sample";
+            _settings["synth.lock-memory"].IntValue = 0;
+            _settings["synth.threadsafe-api"].IntValue = 1;
+            _settings["synth.gain"].DoubleValue = 1.0d;
+            _settings["synth.polyphony"].IntValue = 1024;
+            _settings["synth.cpu-cores"].IntValue = 2;
+            _settings["synth.midi-channels"].IntValue = 16;
+            _settings["synth.overflow.age"].DoubleValue = 3000;
+            _settings["audio.driver"].StringValue = "file";
+            _settings["audio.periods"].IntValue = 8;
+            _settings["audio.period-size"].IntValue = 4096;
+            _settings["midi.autoconnect"].IntValue = 1;
+            _settings["player.reset-synth"].IntValue = 0;
+            _settings["synth.midi-bank-select"].StringValue = "gm";
+            //_settings["synth.verbose"].IntValue = 1; // Useful for debugging.
+        }
+        catch (Exception e)
+        {
+            _midiSawmill.Warning(
+                "Failed to initialize fluidsynth due to exception, disabling MIDI support:\n{0}", e);
+            _failedInitialize = true;
+            return;
         }
 
-        private static readonly string[] LinuxSoundfonts =
-        {
-            "/usr/share/soundfonts/default.sf2",
-            "/usr/share/soundfonts/FluidR3_GM.sf2",
-            "/usr/share/soundfonts/freepats-general-midi.sf2",
-            "/usr/share/sounds/sf2/default.sf2",
-            "/usr/share/sounds/sf2/FluidR3_GM.sf2",
-            "/usr/share/sounds/sf2/TimGM6mb.sf2",
+        _midiThread = new Thread(ThreadUpdate);
+        _midiThread.Start();
+
+        _broadPhaseSystem = EntitySystem.Get<SharedPhysicsSystem>();
+        FluidsynthInitialized = true;
+    }
+
+    private void LoggerDelegate(NFluidsynth.Logger.LogLevel level, string message, IntPtr data)
+    {
+        var rLevel = level switch {
+            NFluidsynth.Logger.LogLevel.Panic => LogLevel.Error,
+            NFluidsynth.Logger.LogLevel.Error => LogLevel.Error,
+            NFluidsynth.Logger.LogLevel.Warning => LogLevel.Warning,
+            NFluidsynth.Logger.LogLevel.Information => LogLevel.Info,
+            NFluidsynth.Logger.LogLevel.Debug => LogLevel.Debug,
+            _ => LogLevel.Debug
         };
+        _sawmill.Log(rLevel, message);
+    }
 
-        private const string WindowsSoundfont = @"C:\WINDOWS\system32\drivers\gm.dls";
-
-        private const string OsxSoundfont =
-            "/System/Library/Components/CoreAudio.component/Contents/Resources/gs_instruments.dls";
-
-        private const string FallbackSoundfont = "/Midi/fallback.sf2";
-
-        private readonly ResourceLoaderCallbacks _soundfontLoaderCallbacks = new();
-
-        private bool FluidsynthInitialized;
-        private bool _failedInitialize;
-
-        private NFluidsynth.Logger.LoggerDelegate _loggerDelegate = default!;
-        private ISawmill _sawmill = default!;
-
-        [ViewVariables(VVAccess.ReadWrite)]
-        public int OcclusionCollisionMask { get; set; }
-
-        private void InitializeFluidsynth()
+    public IMidiRenderer? GetNewRenderer(bool mono = true)
+    {
+        if (!FluidsynthInitialized)
         {
-            if (FluidsynthInitialized || _failedInitialize) return;
+            InitializeFluidsynth();
 
-            _volume = _cfgMan.GetCVar(CVars.MidiVolume);
-            _cfgMan.OnValueChanged(CVars.MidiVolume, value =>
+            if (!FluidsynthInitialized) // init failed
             {
-                _volume = value;
-                _volumeDirty = true;
-            }, true);
-
-            _midiSawmill = Logger.GetSawmill("midi");
-            _sawmill = Logger.GetSawmill("midi.fluidsynth");
-            _loggerDelegate = LoggerDelegate;
-
-            try
-            {
-                NFluidsynth.Logger.SetLoggerMethod(_loggerDelegate); // Will cause a safe DllNotFoundException if not available.
-
-                _settings = new Settings();
-                _settings["synth.sample-rate"].DoubleValue = 44100;
-                _settings["player.timing-source"].StringValue = "sample";
-                _settings["synth.lock-memory"].IntValue = 0;
-                _settings["synth.threadsafe-api"].IntValue = 1;
-                _settings["synth.gain"].DoubleValue = 1.0d;
-                _settings["synth.polyphony"].IntValue = 1024;
-                _settings["synth.cpu-cores"].IntValue = 2;
-                _settings["synth.overflow.age"].DoubleValue = 3000;
-                _settings["audio.driver"].StringValue = "file";
-                _settings["audio.periods"].IntValue = 8;
-                _settings["audio.period-size"].IntValue = 4096;
-                _settings["midi.autoconnect"].IntValue = 1;
-                _settings["player.reset-synth"].IntValue = 0;
-                _settings["synth.midi-bank-select"].StringValue = "gm";
-            }
-            catch (Exception e)
-            {
-                Logger.WarningS("midi",
-                    "Failed to initialize fluidsynth due to exception, disabling MIDI support:\n{0}", e);
-                _failedInitialize = true;
-                return;
-            }
-
-            _midiThread = new Thread(ThreadUpdate);
-            _midiThread.Start();
-
-            _broadPhaseSystem = EntitySystem.Get<SharedPhysicsSystem>();
-            FluidsynthInitialized = true;
-        }
-
-        private void LoggerDelegate(NFluidsynth.Logger.LogLevel level, string message, IntPtr data)
-        {
-            var rLevel = level switch {
-                NFluidsynth.Logger.LogLevel.Panic => LogLevel.Error,
-                NFluidsynth.Logger.LogLevel.Error => LogLevel.Error,
-                NFluidsynth.Logger.LogLevel.Warning => LogLevel.Warning,
-                NFluidsynth.Logger.LogLevel.Information => LogLevel.Info,
-                NFluidsynth.Logger.LogLevel.Debug => LogLevel.Debug,
-                _ => LogLevel.Debug
-            };
-            _sawmill.Log(rLevel, message);
-        }
-
-        public IMidiRenderer? GetNewRenderer()
-        {
-            if (!FluidsynthInitialized)
-            {
-                InitializeFluidsynth();
-
-                if (!FluidsynthInitialized) // init failed
-                {
-                    return null;
-                }
-            }
-
-            var soundfontLoader = SoundFontLoader.NewDefaultSoundFontLoader(_settings);
-
-            // Just making double sure these don't get GC'd.
-            // They shouldn't, MidiRenderer keeps a ref, but making sure...
-            var handle = GCHandle.Alloc(soundfontLoader);
-
-            try
-            {
-                soundfontLoader.SetCallbacks(_soundfontLoaderCallbacks);
-
-                var renderer = new MidiRenderer(_settings!, soundfontLoader);
-
-                foreach (var file in _resourceManager.ContentFindFiles(("/Audio/MidiCustom/")))
-                {
-                    if (file.Extension != "sf2" && file.Extension != "dls") continue;
-                    renderer.LoadSoundfont(file.ToString());
-                }
-
-                // Since the last loaded soundfont takes priority, we load the fallback soundfont before the soundfont.
-                renderer.LoadSoundfont(FallbackSoundfont);
-
-                if (OperatingSystem.IsLinux())
-                {
-                    foreach (var filepath in LinuxSoundfonts)
-                    {
-                        if (!File.Exists(filepath) || !SoundFont.IsSoundFont(filepath)) continue;
-
-                        try
-                        {
-                            renderer.LoadSoundfont(filepath, true);
-                        }
-                        catch (Exception)
-                        {
-                            continue;
-                        }
-
-                        break;
-                    }
-                }
-                else if (OperatingSystem.IsMacOS())
-                {
-                    if (File.Exists(OsxSoundfont) && SoundFont.IsSoundFont(OsxSoundfont))
-                        renderer.LoadSoundfont(OsxSoundfont, true);
-                }
-                else if (OperatingSystem.IsWindows())
-                {
-                    if (File.Exists(WindowsSoundfont) && SoundFont.IsSoundFont(WindowsSoundfont))
-                        renderer.LoadSoundfont(WindowsSoundfont, true);
-                }
-
-                renderer.Source.SetVolume(Volume);
-
-                lock (_renderers)
-                {
-                    _renderers.Add(renderer);
-                }
-                return renderer;
-            }
-            finally
-            {
-                handle.Free();
+                return null;
             }
         }
 
-        public void FrameUpdate(float frameTime)
+        var soundfontLoader = SoundFontLoader.NewDefaultSoundFontLoader(_settings);
+
+        // Just making double sure these don't get GC'd.
+        // They shouldn't, MidiRenderer keeps a ref, but making sure...
+        var handle = GCHandle.Alloc(soundfontLoader);
+
+        try
         {
-            if (!FluidsynthInitialized)
+            soundfontLoader.SetCallbacks(_soundfontLoaderCallbacks);
+
+            var renderer = new MidiRenderer(_settings!, soundfontLoader, mono, this, _clydeAudio, _taskManager, _midiSawmill);
+
+            foreach (var file in _resourceManager.ContentFindFiles(("/Audio/MidiCustom/")))
             {
-                return;
+                if (file.Extension != "sf2" && file.Extension != "dls") continue;
+                renderer.LoadSoundfont(file.ToString());
             }
 
-            // Update positions of streams every frame.
-            foreach (var renderer in _renderers)
+            // Since the last loaded soundfont takes priority, we load the fallback soundfont before the soundfont.
+            renderer.LoadSoundfont(FallbackSoundfont);
+
+            if (OperatingSystem.IsLinux())
             {
-                if (renderer.Disposed)
-                    continue;
-
-                if(_volumeDirty)
-                    renderer.Source.SetVolume(Volume);
-
-                if (!renderer.Mono)
+                foreach (var filepath in LinuxSoundfonts)
                 {
-                    renderer.Source.SetGlobal();
-                    continue;
-                }
+                    if (!File.Exists(filepath) || !SoundFont.IsSoundFont(filepath)) continue;
 
-                MapCoordinates? mapPos = null;
-                var trackingEntity = renderer.TrackingEntity != null && !_entityManager.Deleted(renderer.TrackingEntity);
-                if (trackingEntity)
-                {
-                    renderer.TrackingCoordinates = _entityManager.GetComponent<TransformComponent>(renderer.TrackingEntity!.Value).Coordinates;
-                }
-
-                if (renderer.TrackingCoordinates != null)
-                {
-                    mapPos = renderer.TrackingCoordinates.Value.ToMap(_entityManager);
-                }
-
-                if (mapPos != null && mapPos.Value.MapId == _eyeManager.CurrentMap)
-                {
-                    var pos = mapPos.Value;
-
-                    var sourceRelative = _eyeManager.CurrentEye.Position.Position - pos.Position;
-                    var occlusion = 0f;
-                    if (sourceRelative.Length > 0)
+                    try
                     {
-                        occlusion = _broadPhaseSystem.IntersectRayPenetration(
-                            pos.MapId,
-                            new CollisionRay(
-                                pos.Position,
-                                sourceRelative.Normalized,
-                                OcclusionCollisionMask),
-                            sourceRelative.Length,
-                            renderer.TrackingEntity);
+                        renderer.LoadSoundfont(filepath, true);
+                    }
+                    catch (Exception)
+                    {
+                        continue;
                     }
 
-                    renderer.Source.SetOcclusion(occlusion);
-
-                    if (!renderer.Source.SetPosition(pos.Position))
-                    {
-                        return;
-                    }
-
-                    if (trackingEntity)
-                    {
-                        renderer.Source.SetVelocity(renderer.TrackingEntity!.Value.GlobalLinearVelocity());
-                    }
-                }
-                else
-                {
-                    renderer.Source.SetOcclusion(float.MaxValue);
+                    break;
                 }
             }
-
-            _volumeDirty = false;
-        }
-
-        /// <summary>
-        ///     Main method for the thread rendering the midi audio.
-        /// </summary>
-        private void ThreadUpdate()
-        {
-            while (_alive)
+            else if (OperatingSystem.IsMacOS())
             {
-                lock (_renderers)
-                {
-                    for (var i = 0; i < _renderers.Count; i++)
-                    {
-                        var renderer = _renderers[i];
-                        if (!renderer.Disposed)
-                            renderer.Render();
-                        else
-                        {
-                            renderer.InternalDispose();
-                            _renderers.Remove(renderer);
-                        }
-                    }
-                }
-
-                Thread.Sleep(1);
+                if (File.Exists(OsxSoundfont) && SoundFont.IsSoundFont(OsxSoundfont))
+                    renderer.LoadSoundfont(OsxSoundfont, true);
+            }
+            else if (OperatingSystem.IsWindows())
+            {
+                if (File.Exists(WindowsSoundfont) && SoundFont.IsSoundFont(WindowsSoundfont))
+                    renderer.LoadSoundfont(WindowsSoundfont, true);
             }
-        }
 
-        public void Shutdown()
-        {
-            _alive = false;
-            _midiThread?.Join();
-            _settings?.Dispose();
+            // load every soundfont from the user data directory
+            _midiSawmill.Debug($"loading soundfonts from {CustomSoundfontDirectory.ToRelativePath().ToString()}/*");
+            var enumerator = _resourceManager.UserData.Find($"{CustomSoundfontDirectory.ToRelativePath().ToString()}/*").Item1;
+            foreach (var soundfont in enumerator)
+            {
+                if (soundfont.Extension != "sf2" && soundfont.Extension != "dls") continue;
+                _midiSawmill.Debug($"loading soundfont {soundfont}");
+                renderer.LoadSoundfont(soundfont.ToString());
+            }
+
+            renderer.Source.SetVolume(Volume);
 
             lock (_renderers)
             {
-                foreach (var renderer in _renderers)
-                {
-                    renderer?.Dispose();
-                }
+                _renderers.Add(renderer);
+            }
+            return renderer;
+        }
+        finally
+        {
+            handle.Free();
+        }
+    }
+
+    public void FrameUpdate(float frameTime)
+    {
+        if (!FluidsynthInitialized)
+        {
+            return;
+        }
+
+        // Update positions of streams every frame.
+        foreach (var renderer in _renderers)
+        {
+            if (renderer.Disposed)
+                continue;
+
+            if(_volumeDirty)
+                renderer.Source.SetVolume(Volume);
+
+            if (!renderer.Mono)
+            {
+                renderer.Source.SetGlobal();
+                continue;
             }
 
-            if (FluidsynthInitialized && !_failedInitialize)
+            MapCoordinates? mapPos = null;
+            var trackingEntity = renderer.TrackingEntity != null && !_entityManager.Deleted(renderer.TrackingEntity);
+            if (trackingEntity)
             {
-                NFluidsynth.Logger.SetLoggerMethod(null);
+                renderer.TrackingCoordinates = _entityManager.GetComponent<TransformComponent>(renderer.TrackingEntity!.Value).Coordinates;
+            }
+
+            if (renderer.TrackingCoordinates != null)
+            {
+                mapPos = renderer.TrackingCoordinates.Value.ToMap(_entityManager);
+            }
+
+            if (mapPos != null && mapPos.Value.MapId == _eyeManager.CurrentMap)
+            {
+                var pos = mapPos.Value;
+
+                var sourceRelative = _eyeManager.CurrentEye.Position.Position - pos.Position;
+                var occlusion = 0f;
+                if (sourceRelative.Length > 0)
+                {
+                    occlusion = _broadPhaseSystem.IntersectRayPenetration(
+                        pos.MapId,
+                        new CollisionRay(
+                            pos.Position,
+                            sourceRelative.Normalized,
+                            OcclusionCollisionMask),
+                        sourceRelative.Length,
+                        renderer.TrackingEntity);
+                }
+
+                renderer.Source.SetOcclusion(occlusion);
+
+                if (!renderer.Source.SetPosition(pos.Position))
+                {
+                    return;
+                }
+
+                if (trackingEntity)
+                {
+                    renderer.Source.SetVelocity(renderer.TrackingEntity!.Value.GlobalLinearVelocity());
+                }
+            }
+            else
+            {
+                renderer.Source.SetOcclusion(float.MaxValue);
             }
         }
 
-        /// <summary>
-        ///     This class is used to load soundfonts.
-        /// </summary>
-        private sealed class ResourceLoaderCallbacks : SoundFontLoaderCallbacks
+        _volumeDirty = false;
+    }
+
+    /// <summary>
+    ///     Main method for the thread rendering the midi audio.
+    /// </summary>
+    private void ThreadUpdate()
+    {
+        while (_alive)
         {
-            private readonly Dictionary<int, Stream> _openStreams = new();
-            private int _nextStreamId = 1;
-
-            public override IntPtr Open(string filename)
+            lock (_renderers)
             {
-                if (string.IsNullOrEmpty(filename))
+                for (var i = 0; i < _renderers.Count; i++)
                 {
-                    return IntPtr.Zero;
+                    var renderer = _renderers[i];
+                    if (!renderer.Disposed)
+                        renderer.Render();
+                    else
+                    {
+                        renderer.InternalDispose();
+                        _renderers.Remove(renderer);
+                    }
                 }
+            }
 
-                Stream? stream;
-                var resourceCache = IoCManager.Resolve<IResourceCache>();
-                var resourcePath = new ResourcePath(filename);
+            Thread.Sleep(1);
+        }
+    }
 
-                if (resourcePath.IsRooted && resourceCache.ContentFileExists(filename))
+    public void Shutdown()
+    {
+        _alive = false;
+        _midiThread?.Join();
+        _settings?.Dispose();
+
+        lock (_renderers)
+        {
+            foreach (var renderer in _renderers)
+            {
+                renderer?.Dispose();
+            }
+        }
+
+        if (FluidsynthInitialized && !_failedInitialize)
+        {
+            NFluidsynth.Logger.SetLoggerMethod(null);
+        }
+    }
+
+    /// <summary>
+    ///     Internal method to get a human-readable representation of a <see cref="SequencerEvent"/>.
+    /// </summary>
+    internal static string SequencerEventToString(SequencerEvent midiEvent)
+    {
+        // ReSharper disable once UseStringInterpolation
+        return string.Format(
+            "{0} chan:{1:D2} key:{2:D5} bank:{3:D2} ctrl:{4:D5} dur:{5:D5} pitch:{6:D5} prog:{7:D3} val:{8:D5} vel:{9:D5}",
+            midiEvent.Type.ToString().PadLeft(22),
+            midiEvent.Channel,
+            midiEvent.Key,
+            midiEvent.Bank,
+            midiEvent.Control,
+            midiEvent.Duration,
+            midiEvent.Pitch,
+            midiEvent.Program,
+            midiEvent.Value,
+            midiEvent.Velocity);
+    }
+
+    /// <summary>
+    ///     This class is used to load soundfonts.
+    /// </summary>
+    private sealed class ResourceLoaderCallbacks : SoundFontLoaderCallbacks
+    {
+        private readonly Dictionary<int, Stream> _openStreams = new();
+        private int _nextStreamId = 1;
+
+        public override IntPtr Open(string filename)
+        {
+            if (string.IsNullOrEmpty(filename))
+            {
+                return IntPtr.Zero;
+            }
+
+            Stream? stream;
+            var resourceCache = IoCManager.Resolve<IResourceCache>();
+            var resourcePath = new ResourcePath(filename);
+
+            if (resourcePath.IsRooted)
+            {
+                // is it in content?
+                if (resourceCache.ContentFileExists(filename))
                 {
                     if (!resourceCache.TryContentFileRead(filename, out stream))
                         return IntPtr.Zero;
                 }
+                // is it in userdata?
+                else if (resourceCache.UserData.Exists(resourcePath))
+                {
+                    stream = resourceCache.UserData.OpenRead(resourcePath);
+                }
                 else if (File.Exists(filename))
                 {
                     stream = File.OpenRead(filename);
@@ -421,73 +453,81 @@ namespace Robust.Client.Audio.Midi
                 {
                     return IntPtr.Zero;
                 }
-
-                var id = _nextStreamId++;
-
-                _openStreams.Add(id, stream);
-
-                return (IntPtr) id;
+            }
+            else if (File.Exists(filename))
+            {
+                stream = File.OpenRead(filename);
+            }
+            else
+            {
+                return IntPtr.Zero;
             }
 
-            public override unsafe int Read(IntPtr buf, long count, IntPtr sfHandle)
-            {
-                var length = (int) count;
-                var span = new Span<byte>(buf.ToPointer(), length);
-                var stream = _openStreams[(int) sfHandle];
+            var id = _nextStreamId++;
 
-                // Fluidsynth's docs state that this method should leave the buffer unmodified if it fails. (returns -1)
-                try
+            _openStreams.Add(id, stream);
+
+            return (IntPtr) id;
+        }
+
+        public override unsafe int Read(IntPtr buf, long count, IntPtr sfHandle)
+        {
+            var length = (int) count;
+            var span = new Span<byte>(buf.ToPointer(), length);
+            var stream = _openStreams[(int) sfHandle];
+
+            // Fluidsynth's docs state that this method should leave the buffer unmodified if it fails. (returns -1)
+            try
+            {
+                // Fluidsynth does a LOT of tiny allocations (frankly, way too much).
+                if (count < 1024)
                 {
-                    // Fluidsynth does a LOT of tiny allocations (frankly, way too much).
-                    if (count < 1024)
-                    {
-                        // ReSharper disable once SuggestVarOrType_Elsewhere
-                        Span<byte> buffer = stackalloc byte[(int)count];
+                    // ReSharper disable once SuggestVarOrType_Elsewhere
+                    Span<byte> buffer = stackalloc byte[(int)count];
 
-                        stream.ReadExact(buffer);
+                    stream.ReadExact(buffer);
 
-                        buffer.CopyTo(span);
-                    }
-                    else
-                    {
-                        var buffer = stream.ReadExact(length);
-
-                        buffer.CopyTo(span);
-                    }
+                    buffer.CopyTo(span);
                 }
-                catch (EndOfStreamException)
+                else
                 {
-                    return -1;
+                    var buffer = stream.ReadExact(length);
+
+                    buffer.CopyTo(span);
                 }
-
-                return 0;
             }
-
-            public override int Seek(IntPtr sfHandle, int offset, SeekOrigin origin)
+            catch (EndOfStreamException)
             {
-                var stream = _openStreams[(int) sfHandle];
-
-                stream.Seek(offset, origin);
-
-                return 0;
+                return -1;
             }
 
-            public override int Tell(IntPtr sfHandle)
-            {
-                var stream = _openStreams[(int) sfHandle];
+            return 0;
+        }
 
-                return (int) stream.Position;
-            }
+        public override int Seek(IntPtr sfHandle, int offset, SeekOrigin origin)
+        {
+            var stream = _openStreams[(int) sfHandle];
 
-            public override int Close(IntPtr sfHandle)
-            {
-                if (!_openStreams.Remove((int) sfHandle, out var stream))
-                    return -1;
+            stream.Seek(offset, origin);
 
-                stream.Dispose();
-                return 0;
+            return 0;
+        }
+
+        public override int Tell(IntPtr sfHandle)
+        {
+            var stream = _openStreams[(int) sfHandle];
+
+            return (int) stream.Position;
+        }
+
+        public override int Close(IntPtr sfHandle)
+        {
+            if (!_openStreams.Remove((int) sfHandle, out var stream))
+                return -1;
+
+            stream.Dispose();
+            return 0;
 
-            }
         }
     }
 }

Robust.Client/BaseClient.cs

@@ -74,7 +74,7 @@ namespace Robust.Client
         {
             if (RunLevel == ClientRunLevel.Connecting)
             {
-                _net.Shutdown("Client mashing that connect button.");
+                _net.Reset("Client mashing that connect button.");
                 Reset();
             }
 

Robust.Client/Console/ClientConsoleHost.cs

@@ -134,7 +134,7 @@ namespace Robust.Client.Console
             if (!NetManager.IsConnected) // we don't care about session on client
                 return;
 
-            var msg = NetManager.CreateNetMessage<MsgConCmd>();
+            var msg = new MsgConCmd();
             msg.Text = command;
             NetManager.ClientSendMessage(msg);
         }
@@ -198,7 +198,7 @@ namespace Robust.Client.Console
             if (!NetManager.IsConnected)
                 return;
 
-            var msg = NetManager.CreateNetMessage<MsgConCmdReg>();
+            var msg = new MsgConCmdReg();
             NetManager.ClientSendMessage(msg);
 
             _requestedCommands = true;

Robust.Client/Console/Commands/SendGarbageCommand.cs

@@ -15,7 +15,7 @@ namespace Robust.Client.Console.Commands
             // MsgStringTableEntries is registered as NetMessageAccept.Client so the server will immediately deny it.
             // And kick us.
             var net = IoCManager.Resolve<IClientNetManager>();
-            var msg = net.CreateNetMessage<MsgStringTableEntries>();
+            var msg = new MsgStringTableEntries();
             msg.Entries = new MsgStringTableEntries.Entry[0];
             net.ClientSendMessage(msg);
         }

Robust.Client/Console/ScriptClient.ScriptConsoleServer.cs

@@ -35,7 +35,7 @@ namespace Robust.Client.Console
 
                 RunButton.Disabled = true;
 
-                var msg = _client._netManager.CreateNetMessage<MsgScriptEval>();
+                var msg = new MsgScriptEval();
                 msg.ScriptSession = _session;
                 msg.Code = _lastEnteredText = InputBar.Text;
 
@@ -48,7 +48,7 @@ namespace Robust.Client.Console
 
             protected override void Complete()
             {
-                var msg = _client._netManager.CreateNetMessage<MsgScriptCompletion>();
+                var msg = new MsgScriptCompletion();
                 msg.ScriptSession = _session;
                 msg.Code = InputBar.Text;
                 msg.Cursor = InputBar.CursorPosition;

Robust.Client/Console/ScriptClient.cs

@@ -65,7 +65,7 @@ namespace Robust.Client.Console
                 throw new InvalidOperationException("We do not have scripting permission.");
             }
 
-            var msg = _netManager.CreateNetMessage<MsgScriptStart>();
+            var msg = new MsgScriptStart();
             msg.ScriptSession = _nextSessionId++;
             _netManager.ClientSendMessage(msg);
         }
@@ -74,7 +74,7 @@ namespace Robust.Client.Console
         {
             _activeConsoles.Remove(session);
 
-            var msg = _netManager.CreateNetMessage<MsgScriptStop>();
+            var msg = new MsgScriptStop();
             msg.ScriptSession = session;
             _netManager.ClientSendMessage(msg);
         }

Robust.Client/GameController/GameController.cs

@@ -21,7 +21,6 @@ using Robust.Shared;
 using Robust.Shared.Asynchronous;
 using Robust.Shared.Configuration;
 using Robust.Shared.ContentPack;
-using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
@@ -29,6 +28,7 @@ using Robust.Shared.Network;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager;
+using Robust.Shared.Threading;
 using Robust.Shared.Timing;
 using Robust.Shared.Utility;
 using YamlDotNet.RepresentationModel;
@@ -66,6 +66,7 @@ namespace Robust.Client
         [Dependency] private readonly IAuthManager _authManager = default!;
         [Dependency] private readonly IMidiManager _midiManager = default!;
         [Dependency] private readonly IEyeManager _eyeManager = default!;
+        [Dependency] private readonly IParallelManagerInternal _parallelMgr = default!;
 
         private IWebViewManagerHook? _webViewHook;
 
@@ -131,8 +132,9 @@ namespace Robust.Client
             _inputManager.Initialize();
             _console.Initialize();
             _prototypeManager.Initialize();
+            _prototypeManager.LoadDirectory(new ResourcePath("/EnginePrototypes/"));
             _prototypeManager.LoadDirectory(Options.PrototypeDirectory);
-            _prototypeManager.Resync();
+            _prototypeManager.ResolveResults();
             _entityManager.Initialize();
             _mapManager.Initialize();
             _gameStateManager.Initialize();
@@ -326,6 +328,8 @@ namespace Robust.Client
 
             ProfileOptSetup.Setup(_configurationManager);
 
+            _parallelMgr.Initialize();
+
             _resourceCache.Initialize(Options.LoadConfigAndUserData ? userDataDir : null);
 
             var mountOptions = _commandLineArgs != null

Robust.Client/GameObjects/ClientEntityManager.cs

@@ -86,7 +86,7 @@ namespace Robust.Client.GameObjects
 
         public void SendSystemNetworkMessage(EntityEventArgs message, uint sequence)
         {
-            var msg = _networkManager.CreateNetMessage<MsgEntity>();
+            var msg = new MsgEntity();
             msg.Type = EntityMessageType.SystemMessage;
             msg.SystemMessage = message;
             msg.SourceTick = _gameTiming.CurTick;

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

@@ -1,3 +1,4 @@
+using System;
 using Robust.Client.Graphics;
 using Robust.Client.ResourceManagement;
 using Robust.Client.Utility;
@@ -32,11 +33,13 @@ namespace Robust.Client.GameObjects
         public const string LogCategory = "go.comp.icon";
         const string SerializationCache = "icon";
 
+        [Obsolete("Use SpriteSystem instead.")]
         private static IRsiStateLike TextureForConfig(IconComponent compData, IResourceCache resourceCache)
         {
             return compData.Icon?.Default ?? resourceCache.GetFallback<TextureResource>().Texture;
         }
 
+        [Obsolete("Use SpriteSystem instead.")]
         public static IRsiStateLike? GetPrototypeIcon(EntityPrototype prototype, IResourceCache resourceCache)
         {
             if (!prototype.Components.TryGetValue("Icon", out var compData))

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

@@ -601,8 +601,10 @@ namespace Robust.Client.GameObjects
         private void RebuildBounds()
         {
             _bounds = new Box2();
-            foreach (var layer in Layers.Where(layer => layer.Visible))
+            foreach (var layer in Layers)
             {
+                if (!layer.Visible) continue;
+
                 _bounds = _bounds.Union(layer.CalculateBoundingBox());
             }
         }
@@ -1520,6 +1522,7 @@ namespace Robust.Client.GameObjects
             }
         }
 
+        [Obsolete("Use SpriteSystem instead.")]
         internal static RSI.State GetFallbackState(IResourceCache cache)
         {
             var rsi = cache.GetResource<RSIResource>("/Textures/error.rsi").RSI;
@@ -1968,7 +1971,7 @@ namespace Robust.Client.GameObjects
             /// <inheritdoc/>
             public Box2 CalculateBoundingBox()
             {
-                var textureSize = PixelSize / EyeManager.PixelsPerMeter;
+                var textureSize = (Vector2) PixelSize / EyeManager.PixelsPerMeter;
 
                 // If the parent has locked rotation and we don't have any rotation,
                 // we can take the quick path of just making a box the size of the texture.

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

@@ -75,6 +75,10 @@ namespace Robust.Client.GameObjects
                 (BoundUserInterface) _dynamicTypeFactory.CreateInstance(type, new[] {this, wrapped.UiKey});
             boundInterface.Open();
             _openInterfaces[wrapped.UiKey] = boundInterface;
+
+            var playerSession = _playerManager.LocalPlayer?.Session;
+            if(playerSession != null)
+                _entityManager.EventBus.RaiseLocalEvent(Owner, new BoundUIOpenedEvent(wrapped.UiKey, Owner, playerSession));
         }
 
         internal void Close(object uiKey, bool remoteCall)

Robust.Client/GameObjects/EntitySystems/DebugEntityLookupSystem.cs

@@ -0,0 +1,105 @@
+using System.Collections.Generic;
+using Robust.Client.Graphics;
+using Robust.Shared.Console;
+using Robust.Shared.Containers;
+using Robust.Shared.Enums;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Utility;
+using Color = Robust.Shared.Maths.Color;
+
+namespace Robust.Client.GameObjects;
+
+public sealed class DebugEntityLookupCommand : IConsoleCommand
+{
+    public string Command => "togglelookup";
+    public string Description => "Shows / hides entitylookup bounds via an overlay";
+    public string Help => $"{Command}";
+    public void Execute(IConsoleShell shell, string argStr, string[] args)
+    {
+        EntitySystem.Get<DebugEntityLookupSystem>().Enabled ^= true;
+    }
+}
+
+public sealed class DebugEntityLookupSystem : EntitySystem
+{
+    public bool Enabled
+    {
+        get => _enabled;
+        set
+        {
+            if (_enabled == value) return;
+
+            _enabled = value;
+
+            if (_enabled)
+            {
+                IoCManager.Resolve<IOverlayManager>().AddOverlay(
+                    new EntityLookupOverlay(
+                        EntityManager,
+                        Get<EntityLookupSystem>()));
+            }
+            else
+            {
+                IoCManager.Resolve<IOverlayManager>().RemoveOverlay<EntityLookupOverlay>();
+            }
+        }
+    }
+
+    private bool _enabled;
+}
+
+public sealed class EntityLookupOverlay : Overlay
+{
+    private IEntityManager _entityManager = default!;
+    private EntityLookupSystem _lookup = default!;
+
+    public override OverlaySpace Space => OverlaySpace.WorldSpace;
+
+    public EntityLookupOverlay(IEntityManager entManager, EntityLookupSystem lookup)
+    {
+        _entityManager = entManager;
+        _lookup = lookup;
+    }
+
+    protected internal override void Draw(in OverlayDrawArgs args)
+    {
+        var worldHandle = args.WorldHandle;
+        var xformQuery = _entityManager.GetEntityQuery<TransformComponent>();
+
+        foreach (var lookup in _lookup.FindLookupsIntersecting(args.MapId, args.WorldBounds))
+        {
+            var lookupXform = xformQuery.GetComponent(lookup.Owner);
+
+            var (_, rotation, matrix, invMatrix) = lookupXform.GetWorldPositionRotationMatrixWithInv();
+
+            worldHandle.SetTransform(matrix);
+
+
+            var lookupAABB = invMatrix.TransformBox(args.WorldBounds);
+            var ents = new List<EntityUid>();
+
+            // Gonna allocate a lot but debug overlay sooo
+            lookup.Tree._b2Tree.FastQuery(ref lookupAABB, (ref EntityUid data) =>
+            {
+                ents.Add(data);
+            });
+
+            foreach (var ent in ents)
+            {
+                if (_entityManager.Deleted(ent)) continue;
+                var xform = xformQuery.GetComponent(ent);
+
+                //DebugTools.Assert(!ent.IsInContainer(_entityManager));
+                var (entPos, entRot) = xform.GetWorldPositionRotation();
+
+                var lookupPos = invMatrix.Transform(entPos);
+                var lookupRot = entRot - rotation;
+
+                var aabb = _lookup.GetAABB(ent, lookupPos, lookupRot, xform, xformQuery);
+
+                worldHandle.DrawRect(aabb, Color.Blue.WithAlpha(0.2f));
+            }
+        }
+    }
+}

Robust.Client/GameObjects/EntitySystems/SpriteSystem.Specifier.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using JetBrains.Annotations;
 using Robust.Client.Graphics;
 using Robust.Client.ResourceManagement;
@@ -17,13 +18,13 @@ public sealed partial class SpriteSystem
     [Dependency] private readonly IPrototypeManager _proto = default!;
     [Dependency] private readonly IResourceCache _resourceCache = default!;
 
-    [Pure]
+    private readonly Dictionary<string, IRsiStateLike> _cachedPrototypeIcons = new();
+
     public Texture Frame0(SpriteSpecifier specifier)
     {
         return RsiStateLike(specifier).Default;
     }
 
-    [Pure]
     public IRsiStateLike RsiStateLike(SpriteSpecifier specifier)
     {
         switch (specifier)
@@ -35,38 +36,71 @@ public sealed partial class SpriteSystem
                 return GetState(rsi);
 
             case SpriteSpecifier.EntityPrototype prototypeIcon:
-                if (!_proto.TryIndex<EntityPrototype>(prototypeIcon.EntityPrototypeId, out var prototype))
-                {
-                    Logger.Error("Failed to load PrototypeIcon {0}", prototypeIcon.EntityPrototypeId);
-                    return SpriteComponent.GetFallbackState(_resourceCache);
-                }
-
-                return SpriteComponent.GetPrototypeIcon(prototype, _resourceCache);
+                return GetPrototypeIcon(prototypeIcon.EntityPrototypeId);
 
             default:
                 throw new NotSupportedException();
         }
     }
 
-    [Pure]
-    public IRsiStateLike GetPrototypeIcon(EntityPrototype prototype, IResourceCache resourceCache)
+    /// <summary>
+    ///     Returns an icon for a given <see cref="EntityPrototype"/> ID, or a fallback in case of an error.
+    ///     This method caches the result based on the prototype identifier.
+    /// </summary>
+    public IRsiStateLike GetPrototypeIcon(string prototype)
     {
-        var icon = IconComponent.GetPrototypeIcon(prototype, _resourceCache);
-        if (icon != null) return icon;
+        // Check if this prototype has been cached before, and if so return the result.
+        if (_cachedPrototypeIcons.TryGetValue(prototype, out var cachedResult))
+            return cachedResult;
 
-        if (!prototype.Components.ContainsKey("Sprite"))
+        if (!_proto.TryIndex<EntityPrototype>(prototype, out var entityPrototype))
         {
-            return SpriteComponent.GetFallbackState(resourceCache);
+            // The specified prototype doesn't exist, return the fallback "error" sprite.
+            Logger.Error("Failed to load PrototypeIcon {0}", prototype);
+            return GetFallbackState();
         }
 
+        // Generate the icon and cache it in case it's ever needed again.
+        var result = GetPrototypeIcon(entityPrototype);
+        _cachedPrototypeIcons[prototype] = result;
+
+        return result;
+    }
+
+    /// <summary>
+    ///     Returns an icon for a given <see cref="EntityPrototype"/> ID, or a fallback in case of an error.
+    ///     This method does NOT cache the result.
+    /// </summary>
+    public IRsiStateLike GetPrototypeIcon(EntityPrototype prototype)
+    {
+        // IconComponent takes precedence. If it has a valid icon, return that. Otherwise, continue as normal.
+        if (prototype.Components.TryGetValue("Icon", out var compData)
+            && compData is IconComponent {Icon: {} icon})
+        {
+            return icon.Default;
+        }
+
+        // If the prototype doesn't have a SpriteComponent, then there's nothing we can do but return the fallback.
+        if (!prototype.Components.ContainsKey("Sprite"))
+        {
+            return GetFallbackState();
+        }
+
+        // Finally, we use spawn a dummy entity to get its icon.
         var dummy = Spawn(prototype.ID, MapCoordinates.Nullspace);
         var spriteComponent = EnsureComp<SpriteComponent>(dummy);
-        var result = spriteComponent.Icon ?? SpriteComponent.GetFallbackState(resourceCache);
+        var result = spriteComponent.Icon ?? GetFallbackState();
         Del(dummy);
 
         return result;
     }
 
+    [Pure]
+    public RSI.State GetFallbackState()
+    {
+        return _resourceCache.GetFallback<RSIResource>().RSI["error"];
+    }
+
     [Pure]
     public RSI.State GetState(SpriteSpecifier.Rsi rsiSpecifier)
     {
@@ -79,6 +113,20 @@ public sealed partial class SpriteSystem
         }
 
         Logger.Error("Failed to load RSI {0}", rsiSpecifier.RsiPath);
-        return SpriteComponent.GetFallbackState(_resourceCache);
+        return GetFallbackState();
+    }
+
+    private void OnPrototypesReloaded(PrototypesReloadedEventArgs protoReloaded)
+    {
+        // Check if any EntityPrototype has been changed.
+        if (!protoReloaded.ByType.TryGetValue(typeof(EntityPrototype), out var changedSet))
+            return;
+
+        // Remove all changed prototypes from the cache, if they're there.
+        foreach (var (prototype, _) in changedSet.Modified)
+        {
+            // Let's be lazy and not regenerate them until something needs them again.
+            _cachedPrototypeIcons.Remove(prototype);
+        }
     }
 }

Robust.Client/GameObjects/EntitySystems/SpriteSystem.cs

@@ -23,9 +23,16 @@ namespace Robust.Client.GameObjects
         {
             base.Initialize();
 
+            _proto.PrototypesReloaded += OnPrototypesReloaded;
             SubscribeLocalEvent<SpriteUpdateInertEvent>(QueueUpdateInert);
         }
 
+        public override void Shutdown()
+        {
+            base.Shutdown();
+            _proto.PrototypesReloaded -= OnPrototypesReloaded;
+        }
+
         private void QueueUpdateInert(SpriteUpdateInertEvent ev)
         {
             _inertUpdateQueue.Enqueue(ev.Sprite);

Robust.Client/GameStates/ClientGameStateManager.cs

@@ -409,7 +409,7 @@ namespace Robust.Client.GameStates
 
         private void AckGameState(GameTick sequence)
         {
-            var msg = _network.CreateNetMessage<MsgStateAck>();
+            var msg = new MsgStateAck();
             msg.Sequence = sequence;
             _network.ClientSendMessage(msg);
         }
@@ -429,7 +429,7 @@ namespace Robust.Client.GameStates
         private List<EntityUid> ApplyEntityStates(ReadOnlySpan<EntityState> curEntStates, ReadOnlySpan<EntityUid> deletions,
             ReadOnlySpan<EntityState> nextEntStates)
         {
-            var toApply = new Dictionary<EntityUid, (EntityState?, EntityState?)>();
+            var toApply = new Dictionary<EntityUid, (EntityState?, EntityState?)>(curEntStates.Length);
             var toInitialize = new List<EntityUid>();
             var created = new List<EntityUid>();
 
@@ -548,6 +548,8 @@ namespace Robust.Client.GameStates
 
             if (curState != null)
             {
+                compStateWork.EnsureCapacity(curState.ComponentChanges.Span.Length);
+
                 foreach (var compChange in curState.ComponentChanges.Span)
                 {
                     if (compChange.Deleted)
@@ -580,6 +582,8 @@ namespace Robust.Client.GameStates
 
             if (nextState != null)
             {
+                compStateWork.EnsureCapacity(compStateWork.Count + nextState.ComponentChanges.Span.Length);
+
                 foreach (var compState in nextState.ComponentChanges.Span)
                 {
                     if (compStateWork.TryGetValue(compState.NetID, out var state))

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

@@ -144,7 +144,7 @@ namespace Robust.Client.Graphics.Clyde
 
             var worldAABB = CalcWorldAABB(vp);
             var worldBounds = CalcWorldBounds(vp);
-            var args = new OverlayDrawArgs(space, vpControl, vp, handle, bounds, worldAABB, worldBounds);
+            var args = new OverlayDrawArgs(space, vpControl, vp, handle, bounds, vp.Eye!.Position.MapId, worldAABB, worldBounds);
 
             foreach (var overlay in list)
             {

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

@@ -415,9 +415,15 @@ namespace Robust.Client.Graphics.Clyde
                     case float f:
                         program.SetUniform(name, f);
                         break;
+                    case float[] fArr:
+                        program.SetUniform(name, fArr);
+                        break;
                     case Vector2 vector2:
                         program.SetUniform(name, vector2);
                         break;
+                    case Vector2[] vector2Arr:
+                        program.SetUniform(name, vector2Arr);
+                        break;
                     case Vector3 vector3:
                         program.SetUniform(name, vector3);
                         break;

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

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
@@ -395,12 +395,24 @@ namespace Robust.Client.Graphics.Clyde
                 data.Parameters[name] = value;
             }
 
+            private protected override void SetParameterImpl(string name, float[] value)
+            {
+                var data = Parent._shaderInstances[Handle];
+                data.Parameters[name] = value;
+            }
+
             private protected override void SetParameterImpl(string name, Vector2 value)
             {
                 var data = Parent._shaderInstances[Handle];
                 data.Parameters[name] = value;
             }
 
+            private protected override void SetParameterImpl(string name, Vector2[] value)
+            {
+                var data = Parent._shaderInstances[Handle];
+                data.Parameters[name] = value;
+            }
+
             private protected override void SetParameterImpl(string name, Vector3 value)
             {
                 var data = Parent._shaderInstances[Handle];

Robust.Client/Graphics/Clyde/ClydeHeadless.cs

@@ -412,10 +412,18 @@ namespace Robust.Client.Graphics.Clyde
             {
             }
 
+            private protected override void SetParameterImpl(string name, float[] value)
+            {
+            }
+
             private protected override void SetParameterImpl(string name, Vector2 value)
             {
             }
 
+            private protected override void SetParameterImpl(string name, Vector2[] value)
+            {
+            }
+
             private protected override void SetParameterImpl(string name, Vector3 value)
             {
             }

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

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
 using OpenToolkit.Graphics.OpenGL4;
@@ -234,6 +234,19 @@ namespace Robust.Client.Graphics.Clyde
                 GL.Uniform1(uniformId, single);
             }
 
+            public void SetUniform(string uniformName, float[] singles)
+            {
+                var uniformId = GetUniform(uniformName);
+                GL.Uniform1(uniformId, singles.Length, singles);
+                _clyde.CheckGlError();
+            }
+
+            public void SetUniform(int uniformName, float[] singles)
+            {
+                var uniformId = GetUniform(uniformName);
+                GL.Uniform1(uniformId, singles.Length, singles);
+            }
+
             public void SetUniform(string uniformName, in Matrix3 matrix)
             {
                 var uniformId = GetUniform(uniformName);
@@ -375,6 +388,31 @@ namespace Robust.Client.Graphics.Clyde
                 }
             }
 
+            public void SetUniform(string uniformName, Vector2[] vector)
+            {
+                var uniformId = GetUniform(uniformName);
+                SetUniformDirect(uniformId, vector);
+            }
+
+            public void SetUniform(int uniformName, Vector2[] vector)
+            {
+                var uniformId = GetUniform(uniformName);
+                SetUniformDirect(uniformId, vector);
+            }
+
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            private void SetUniformDirect(int slot, Vector2[] vectors)
+            {
+                unsafe
+                {
+                    fixed (Vector2* ptr = &vectors[0])
+                    {
+                        GL.Uniform2(slot, vectors.Length, (float*)ptr);
+                        _clyde.CheckGlError();
+                    }
+                }
+            }
+
             public void SetUniformTexture(string uniformName, TextureUnit textureUnit)
             {
                 var uniformId = GetUniform(uniformName);

Robust.Client/Graphics/Overlays/Overlay.cs

@@ -98,7 +98,7 @@ namespace Robust.Client.Graphics
                 handle = renderHandle.DrawingHandleWorld;
             }
 
-            var args = new OverlayDrawArgs(currentSpace, vpControl, vp, handle, screenBox, worldBox, worldBounds);
+            var args = new OverlayDrawArgs(currentSpace, vpControl, vp, handle, screenBox, vp.Eye!.Position.MapId, worldBox, worldBounds);
 
             Draw(args);
         }

Robust.Client/Graphics/Overlays/OverlayDrawArgs.cs

@@ -1,6 +1,7 @@
 using JetBrains.Annotations;
 using Robust.Client.UserInterface.CustomControls;
 using Robust.Shared.Enums;
+using Robust.Shared.Map;
 using Robust.Shared.Maths;
 
 namespace Robust.Client.Graphics
@@ -38,6 +39,11 @@ namespace Robust.Client.Graphics
         /// </summary>
         public readonly UIBox2i ViewportBounds;
 
+        /// <summary>
+        /// <see cref="MapId"/> of the viewport's eye.
+        /// </summary>
+        public readonly MapId MapId;
+
         /// <summary>
         ///     AABB enclosing the area visible in the viewport.
         /// </summary>
@@ -57,6 +63,7 @@ namespace Robust.Client.Graphics
             IClydeViewport viewport,
             DrawingHandleBase drawingHandle,
             in UIBox2i viewportBounds,
+            in MapId mapId,
             in Box2 worldAabb,
             in Box2Rotated worldBounds)
         {
@@ -65,6 +72,7 @@ namespace Robust.Client.Graphics
             Viewport = viewport;
             DrawingHandle = drawingHandle;
             ViewportBounds = viewportBounds;
+            MapId = mapId;
             WorldAABB = worldAabb;
             WorldBounds = worldBounds;
         }

Robust.Client/Graphics/Shaders/ParsedShader.cs

@@ -135,36 +135,42 @@ namespace Robust.Client.Graphics
 
     internal sealed class ShaderDataTypeFull
     {
-        public ShaderDataTypeFull(ShaderDataType type, ShaderPrecisionQualifier prec)
+        public ShaderDataTypeFull(ShaderDataType type, ShaderPrecisionQualifier prec, int? count = null)
         {
             Type = type;
             Precision = prec;
+            Count = count;
         }
 
         public ShaderDataType Type { get; }
         public ShaderPrecisionQualifier Precision { get; }
 
+        public int? Count;
+
+        public bool IsArray => Count != null;
+
         public string GetNativeType()
         {
-            if (Precision == ShaderPrecisionQualifier.Low)
+            string? precision = Precision switch
             {
-                return "lowp " + Type.GetNativeType();
-            }
-            else if (Precision == ShaderPrecisionQualifier.Medium)
-            {
-                return "mediump " + Type.GetNativeType();
-            }
-            else if (Precision == ShaderPrecisionQualifier.High)
-            {
-                return "highp " + Type.GetNativeType();
-            }
-            return Type.GetNativeType();
+                ShaderPrecisionQualifier.Low => "lowp ",
+                ShaderPrecisionQualifier.Medium => "mediump ",
+                ShaderPrecisionQualifier.High => "highp ",
+                _ => null,
+            };
+
+            return IsArray ? $"{precision}{Type.GetNativeType()}[{Count}]" : $"{precision}{Type.GetNativeType()}";
         }
 
         public bool TypePrecisionConsistent()
         {
             return Type.TypeHasPrecision() == (Precision != ShaderPrecisionQualifier.None);
         }
+
+        public bool TypeCountConsistent()
+        {
+            return Count == null || Type.TypeSupportsArrays();
+        }
     }
 
     internal static class ShaderEnumExt
@@ -203,6 +209,14 @@ namespace Robust.Client.Graphics
                 (type == ShaderDataType.Mat4);
         }
 
+        public static bool TypeSupportsArrays(this ShaderDataType type)
+        {
+            // TODO: add support for int, and vec3/4 arrays
+            return
+                (type == ShaderDataType.Float) ||
+                (type == ShaderDataType.Vec2);
+        }
+
         [SuppressMessage("ReSharper", "StringLiteralTypo")]
         private static readonly Dictionary<ShaderDataType, string> _nativeTypes = new()
         {

Robust.Client/Graphics/Shaders/ShaderInstance.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using Robust.Shared.Maths;
 
 namespace Robust.Client.Graphics
@@ -119,6 +119,13 @@ namespace Robust.Client.Graphics
             SetParameterImpl(name, value);
         }
 
+        public void SetParameter(string name, float[] value)
+        {
+            EnsureAlive();
+            EnsureMutable();
+            SetParameterImpl(name, value);
+        }
+
         public void SetParameter(string name, Vector2 value)
         {
             EnsureAlive();
@@ -126,6 +133,13 @@ namespace Robust.Client.Graphics
             SetParameterImpl(name, value);
         }
 
+        public void SetParameter(string name, Vector2[] value)
+        {
+            EnsureAlive();
+            EnsureMutable();
+            SetParameterImpl(name, value);
+        }
+
         public void SetParameter(string name, Vector3 value)
         {
             EnsureAlive();
@@ -244,7 +258,9 @@ namespace Robust.Client.Graphics
         private protected abstract ShaderInstance DuplicateImpl();
 
         private protected abstract void SetParameterImpl(string name, float value);
+        private protected abstract void SetParameterImpl(string name, float[] value);
         private protected abstract void SetParameterImpl(string name, Vector2 value);
+        private protected abstract void SetParameterImpl(string name, Vector2[] value);
         private protected abstract void SetParameterImpl(string name, Vector3 value);
         private protected abstract void SetParameterImpl(string name, Vector4 value);
         private protected abstract void SetParameterImpl(string name, Color value);

Robust.Client/Graphics/Shaders/ShaderParser.cs

@@ -504,17 +504,33 @@ namespace Robust.Client.Graphics
                     continue;
                 }
 
-                if (_shaderTypeMap.TryGetValue(wordType.Word, out var ret))
+                if (!_shaderTypeMap.TryGetValue(wordType.Word, out var ret))
+                    throw new ShaderParseException("Expected type", wordType.Position);
+
+                var result = new ShaderDataTypeFull(ret, precision);
+                if (!result.TypePrecisionConsistent())
                 {
-                    var result = new ShaderDataTypeFull(ret, precision);
-                    if (!result.TypePrecisionConsistent())
-                    {
-                        throw new ShaderParseException($"Type {ret} cannot accept precision {precision}", wordType.Position);
-                    }
-                    return result;
+                    throw new ShaderParseException($"Type {ret} cannot accept precision {precision}", wordType.Position);
                 }
 
-                throw new ShaderParseException("Expected type or precision", wordType.Position);
+                // is this type meant to be an array?
+                if (_peekToken() is TokenSymbol bracketOpen && bracketOpen.Symbol == Symbols.BracketOpen)
+                {
+                    _takeToken();
+                    if (_takeToken() is not TokenNumber number || !int.TryParse(number.Number, out var count))
+                        throw new ShaderParseException($"Failed to parse array length", bracketOpen.Position);
+
+                    if (_takeToken() is not TokenSymbol bracketClose || bracketClose.Symbol != Symbols.BracketClosed)
+                        throw new ShaderParseException($"Array length definition missing closing bracket", number.Position);
+
+                    result.Count = count;
+
+                    // are arrays supported by this type?
+                    if (!result.TypeCountConsistent())
+                        throw new ShaderParseException($"Type {ret} does not support arrays", wordType.Position);
+                }
+
+                return result;
             }
         }
 

Robust.Client/Graphics/Shaders/ShaderPrototype.cs

@@ -19,7 +19,7 @@ namespace Robust.Client.Graphics
         [Dependency] private readonly IResourceCache _resourceCache = default!;
 
         [ViewVariables]
-        [DataField("id", required: true)]
+        [IdDataFieldAttribute]
         public string ID { get; } = default!;
 
         private ShaderKind Kind;

Robust.Client/Input/InputManager.cs

@@ -497,7 +497,7 @@ namespace Robust.Client.Input
 
             if (robustMapping.TryGet("binds", out var BaseKeyRegsNode))
             {
-                var baseKeyRegs = serializationManager.ReadValueOrThrow<KeyBindingRegistration[]>(BaseKeyRegsNode);
+                var baseKeyRegs = serializationManager.Read<KeyBindingRegistration[]>(BaseKeyRegsNode);
 
                 foreach (var reg in baseKeyRegs)
                 {
@@ -526,7 +526,7 @@ namespace Robust.Client.Input
 
             if (userData && robustMapping.TryGet("leaveEmpty", out var node))
             {
-                var leaveEmpty = serializationManager.ReadValueOrThrow<BoundKeyFunction[]>(node);
+                var leaveEmpty = serializationManager.Read<BoundKeyFunction[]>(node);
 
                 if (leaveEmpty.Length > 0)
                 {

Robust.Client/Placement/PlacementManager.cs

@@ -418,7 +418,7 @@ namespace Robust.Client.Placement
             if (!IsActive || !Eraser) return;
             if (Hijack != null && Hijack.HijackDeletion(entity)) return;
 
-            var msg = NetworkManager.CreateNetMessage<MsgPlacement>();
+            var msg = new MsgPlacement();
             msg.PlaceType = PlacementManagerMessage.RequestEntRemove;
             msg.EntityUid = entity;
             NetworkManager.ClientSendMessage(msg);
@@ -426,7 +426,7 @@ namespace Robust.Client.Placement
 
         public void HandleRectDeletion(EntityCoordinates start, Box2 rect)
         {
-            var msg = NetworkManager.CreateNetMessage<MsgPlacement>();
+            var msg = new MsgPlacement();
             msg.PlaceType = PlacementManagerMessage.RequestRectRemove;
             msg.EntityCoordinates = new EntityCoordinates(StartPoint.EntityId, rect.BottomLeft);
             msg.RectSize = rect.Size;
@@ -748,7 +748,7 @@ namespace Robust.Client.Placement
                 _pendingTileChanges.Add(tuple);
             }
 
-            var message = NetworkManager.CreateNetMessage<MsgPlacement>();
+            var message = new MsgPlacement();
             message.PlaceType = PlacementManagerMessage.RequestPlacement;
 
             message.Align = CurrentMode.ModeName;

Robust.Client/Player/PlayerManager.cs

@@ -89,7 +89,7 @@ namespace Robust.Client.Player
         {
             LocalPlayer = new LocalPlayer();
 
-            var msgList = _network.CreateNetMessage<MsgPlayerListReq>();
+            var msgList = new MsgPlayerListReq();
             // message is empty
             _network.ClientSendMessage(msgList);
         }

Robust.Client/Prototypes/ClientPrototypeManager.cs

@@ -57,7 +57,7 @@ namespace Robust.Client.Prototypes
 #if !FULL_RELEASE
             var sw = Stopwatch.StartNew();
 
-            var msg = _netManager.CreateNetMessage<MsgReloadPrototypes>();
+            var msg = new MsgReloadPrototypes();
             msg.Paths = _reloadQueue.ToArray();
             _netManager.ClientSendMessage(msg);
 

Robust.Client/ResourceManagement/ResourceTypes/RSIResource.cs

@@ -22,6 +22,8 @@ namespace Robust.Client.ResourceManagement
     {
         private static readonly float[] OneArray = {1};
 
+        public override ResourcePath? Fallback => new("/Textures/error.rsi");
+
         private static readonly JsonSerializerOptions SerializerOptions =
             new JsonSerializerOptions(JsonSerializerDefaults.Web)
             {

Robust.Client/Serialization/AppearanceVisualizerSerializer.cs

@@ -1,10 +1,10 @@
+using System;
 using Robust.Client.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Reflection;
 using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager;
 using Robust.Shared.Serialization.Manager.Attributes;
-using Robust.Shared.Serialization.Manager.Result;
 using Robust.Shared.Serialization.Markdown;
 using Robust.Shared.Serialization.Markdown.Mapping;
 using Robust.Shared.Serialization.Markdown.Validation;
@@ -16,26 +16,40 @@ namespace Robust.Client.Serialization
     [TypeSerializer]
     public sealed class AppearanceVisualizerSerializer : ITypeSerializer<AppearanceVisualizer, MappingDataNode>
     {
-        public DeserializationResult Read(ISerializationManager serializationManager, MappingDataNode node,
+        public AppearanceVisualizer Read(ISerializationManager serializationManager, MappingDataNode node,
             IDependencyCollection dependencies,
             bool skipHook,
-            ISerializationContext? context = null)
+            ISerializationContext? context = null, AppearanceVisualizer? value = null)
         {
+            Type? type = null;
             if (!node.TryGet("type", out var typeNode))
-                throw new InvalidMappingException("No type specified for AppearanceVisualizer!");
+            {
+                if (value == null)
+                    throw new InvalidMappingException("No type specified for AppearanceVisualizer!");
 
-            if (typeNode is not ValueDataNode typeValueDataNode)
-                throw new InvalidMappingException("Type node not a value node for AppearanceVisualizer!");
+                type = value.GetType();
+            }
+            else
+            {
+                if (typeNode is not ValueDataNode typeValueDataNode)
+                    throw new InvalidMappingException("Type node not a value node for AppearanceVisualizer!");
 
-            var type = IoCManager.Resolve<IReflectionManager>()
-                .YamlTypeTagLookup(typeof(AppearanceVisualizer), typeValueDataNode.Value);
-            if (type == null)
-                throw new InvalidMappingException(
-                    $"Invalid type {typeValueDataNode.Value} specified for AppearanceVisualizer!");
+                type = IoCManager.Resolve<IReflectionManager>()
+                    .YamlTypeTagLookup(typeof(AppearanceVisualizer), typeValueDataNode.Value);
+                if (type == null)
+                    throw new InvalidMappingException(
+                        $"Invalid type {typeValueDataNode.Value} specified for AppearanceVisualizer!");
+
+                if(value != null && !type.IsInstanceOfType(value))
+                {
+                    throw new InvalidMappingException(
+                        $"Specified Type does not match type of provided Value for AppearanceVisualizer! (TypeOfValue: {value.GetType()}, ProvidedValue: {type})");
+                }
+            }
 
             var newNode = node.Copy();
             newNode.Remove("type");
-            return serializationManager.Read(type, newNode, context, skipHook);
+            return (AppearanceVisualizer) serializationManager.Read(type, newNode, context, skipHook, value)!;
         }
 
         public ValidationNode Validate(ISerializationManager serializationManager, MappingDataNode node,

Robust.Client/UserInterface/Controls/ColorSelectorSliders.cs

@@ -0,0 +1,395 @@
+using System;
+using System.Collections.Generic;
+using Robust.Shared.Localization;
+using Robust.Shared.Maths;
+using Robust.Shared.Log;
+
+namespace Robust.Client.UserInterface.Controls;
+
+// condensed version of the original ColorSlider set
+public sealed class ColorSelectorSliders : Control
+{
+    public Color Color
+    {
+        get => _currentColor;
+        set
+        {
+            _updating = true;
+            _currentColor = value;
+
+            Update();
+            _updating = false;
+        }
+    }
+
+    public ColorSelectorType SelectorType
+    {
+        get => _currentType;
+        set
+        {
+            _updating = true;
+            _currentType = value;
+
+            UpdateType();
+            Update();
+            _updating = false;
+        }
+    }
+
+    public bool IsAlphaVisible
+    {
+        get => _isAlphaVisible;
+        set
+        {
+            _isAlphaVisible = value;
+
+            _alphaSliderBox.Visible = _isAlphaVisible;
+        }
+    }
+
+    public Action<Color>? OnColorChanged;
+
+    private bool _updating = false;
+    private Color _currentColor = Color.White;
+    private ColorSelectorType _currentType = ColorSelectorType.Rgb;
+    private bool _isAlphaVisible = false;
+
+    private ColorableSlider _topColorSlider;
+    private ColorableSlider _middleColorSlider;
+    private ColorableSlider _bottomColorSlider;
+    private Slider _alphaSlider;
+
+    private BoxContainer _alphaSliderBox = new();
+
+    private FloatSpinBox _topInputBox;
+    private FloatSpinBox _middleInputBox;
+    private FloatSpinBox _bottomInputBox;
+    private FloatSpinBox _alphaInputBox;
+
+    private Label _topSliderLabel = new();
+    private Label _middleSliderLabel = new();
+    private Label _bottomSliderLabel = new();
+    private Label _alphaSliderLabel = new();
+
+    private OptionButton _typeSelector;
+    private List<ColorSelectorType> _types = new();
+
+    public ColorSelectorSliders()
+    {
+        _topColorSlider = new ColorableSlider
+        {
+            HorizontalExpand = true,
+            VerticalAlignment = VAlignment.Center,
+            MaxValue = 1.0f
+        };
+
+        _middleColorSlider = new ColorableSlider
+        {
+            HorizontalExpand = true,
+            VerticalAlignment = VAlignment.Center,
+            MaxValue = 1.0f
+        };
+
+        _bottomColorSlider = new ColorableSlider
+        {
+            HorizontalExpand = true,
+            VerticalAlignment = VAlignment.Center,
+            MaxValue = 1.0f
+        };
+
+        _alphaSlider = new Slider
+        {
+            HorizontalExpand = true,
+            VerticalAlignment = VAlignment.Center,
+            MaxValue = 1.0f,
+        };
+
+        _topColorSlider.OnValueChanged += _ => { OnColorSet(); };
+        _middleColorSlider.OnValueChanged += _ => { OnColorSet(); };
+        _bottomColorSlider.OnValueChanged += _ => { OnColorSet(); };
+        _alphaSlider.OnValueChanged += _ => { OnColorSet(); };
+
+        _topInputBox = new FloatSpinBox(1f, 2)
+        {
+            IsValid = value => IsSpinBoxValid(value, ColorSliderOrder.Top)
+        };
+
+        _middleInputBox = new FloatSpinBox(1f, 2)
+        {
+            IsValid = value => IsSpinBoxValid(value, ColorSliderOrder.Middle)
+        };
+
+        _bottomInputBox = new FloatSpinBox(1f, 2)
+        {
+            IsValid = value => IsSpinBoxValid(value, ColorSliderOrder.Bottom)
+        };
+
+        _alphaInputBox = new FloatSpinBox(1f, 2)
+        {
+            IsValid = value => IsSpinBoxValid(value, ColorSliderOrder.Alpha)
+        };
+
+        _topInputBox.OnValueChanged += value =>
+        {
+            _topColorSlider.Value = value.Value / GetColorValueDivisor(ColorSliderOrder.Top);
+        };
+
+        _middleInputBox.OnValueChanged += value =>
+        {
+            _middleColorSlider.Value = value.Value / GetColorValueDivisor(ColorSliderOrder.Middle);
+        };
+
+        _bottomInputBox.OnValueChanged += value =>
+        {
+            _bottomColorSlider.Value = value.Value / GetColorValueDivisor(ColorSliderOrder.Bottom);
+        };
+
+        _alphaInputBox.OnValueChanged += value =>
+        {
+            _alphaSlider.Value = value.Value / GetColorValueDivisor(ColorSliderOrder.Alpha);
+        };
+
+        _alphaSliderLabel.Text = Loc.GetString("color-selector-sliders-alpha");
+
+        _typeSelector = new OptionButton();
+        foreach (var ty in Enum.GetValues<ColorSelectorType>())
+        {
+            _typeSelector.AddItem(Loc.GetString($"color-selector-sliders-{ty.ToString().ToLower()}"));
+            _types.Add(ty);
+        }
+
+        _typeSelector.OnItemSelected += args =>
+        {
+            SelectorType = _types[args.Id];
+            _typeSelector.Select(args.Id);
+        };
+
+        // TODO: Maybe some engine widgets could be laid out in XAML?
+
+        var rootBox = new BoxContainer
+        {
+            Orientation = BoxContainer.LayoutOrientation.Vertical
+        };
+        AddChild(rootBox);
+
+        var headerBox = new BoxContainer();
+        rootBox.AddChild(headerBox);
+
+        headerBox.AddChild(_typeSelector);
+
+        var bodyBox = new BoxContainer()
+        {
+            Orientation = BoxContainer.LayoutOrientation.Vertical
+        };
+
+        // pita
+        var topSliderBox = new BoxContainer();
+
+        topSliderBox.AddChild(_topSliderLabel);
+        topSliderBox.AddChild(_topColorSlider);
+        topSliderBox.AddChild(_topInputBox);
+
+        var middleSliderBox = new BoxContainer();
+
+        middleSliderBox.AddChild(_middleSliderLabel);
+        middleSliderBox.AddChild(_middleColorSlider);
+        middleSliderBox.AddChild(_middleInputBox);
+
+        var bottomSliderBox = new BoxContainer();
+
+        bottomSliderBox.AddChild(_bottomSliderLabel);
+        bottomSliderBox.AddChild(_bottomColorSlider);
+        bottomSliderBox.AddChild(_bottomInputBox);
+
+        _alphaSliderBox.Visible = IsAlphaVisible;
+        _alphaSliderBox.AddChild(_alphaSliderLabel);
+        _alphaSliderBox.AddChild(_alphaSlider);
+        _alphaSliderBox.AddChild(_alphaInputBox);
+
+        bodyBox.AddChild(topSliderBox);
+        bodyBox.AddChild(middleSliderBox);
+        bodyBox.AddChild(bottomSliderBox);
+        bodyBox.AddChild(_alphaSliderBox);
+
+        rootBox.AddChild(bodyBox);
+
+        _updating = true;
+        UpdateType();
+        Update();
+        _updating = false;
+    }
+
+    private void UpdateType()
+    {
+        (string topLabel, string middleLabel, string bottomLabel) labels = GetSliderLabels();
+
+        _topSliderLabel.Text = labels.topLabel;
+        _middleSliderLabel.Text = labels.middleLabel;
+        _bottomSliderLabel.Text = labels.bottomLabel;
+    }
+
+    private void Update()
+    {
+        _topColorSlider.SetColor(_currentColor);
+        _middleColorSlider.SetColor(_currentColor);
+        _bottomColorSlider.SetColor(_currentColor);
+
+        switch (SelectorType)
+        {
+            case ColorSelectorType.Rgb:
+                _topColorSlider.Value = Color.R;
+                _middleColorSlider.Value = Color.G;
+                _bottomColorSlider.Value = Color.B;
+
+                _topInputBox.Value = Color.R * 255.0f;
+                _middleInputBox.Value = Color.G * 255.0f;
+                _bottomInputBox.Value = Color.B * 255.0f;
+
+                break;
+            case ColorSelectorType.Hsv:
+                Vector4 color = Color.ToHsv(Color);
+
+                // dumb workaround because the formula for
+                // HSV calculation results in a negative
+                // number in any value past 300 degrees
+                if (color.X > 0)
+                {
+                    _topColorSlider.Value = color.X;
+                    _topInputBox.Value = color.X * 360.0f;
+                }
+                else
+                {
+                    _topInputBox.Value = _topColorSlider.Value * 360.0f;
+                }
+
+                _middleColorSlider.Value = color.Y;
+                _bottomColorSlider.Value = color.Z;
+
+                _middleInputBox.Value = color.Y * 100.0f;
+                _bottomInputBox.Value = color.Z * 100.0f;
+
+
+                break;
+        }
+
+        _alphaSlider.Value = Color.A;
+        _alphaInputBox.Value = Color.A * 100.0f;
+    }
+
+    private bool IsSpinBoxValid(float value, ColorSliderOrder ordering)
+    {
+        if (value < 0)
+        {
+            return false;
+        }
+
+        if (ordering == ColorSliderOrder.Alpha)
+        {
+            return value <= 100.0f;
+        }
+
+        switch (SelectorType)
+        {
+            case ColorSelectorType.Rgb:
+                return value <= byte.MaxValue;
+            case ColorSelectorType.Hsv:
+                switch (ordering)
+                {
+                    case ColorSliderOrder.Top:
+                        return value <= 360.0f;
+                    default:
+                        return value <= 100.0f;
+                }
+        }
+
+        return false;
+    }
+
+    private (string, string, string) GetSliderLabels()
+    {
+        switch (SelectorType)
+        {
+            case ColorSelectorType.Rgb:
+                return (
+                    Loc.GetString("color-selector-sliders-red"),
+                    Loc.GetString("color-selector-sliders-green"),
+                    Loc.GetString("color-selector-sliders-blue")
+                );
+            case ColorSelectorType.Hsv:
+                return (
+                    Loc.GetString("color-selector-sliders-hue"),
+                    Loc.GetString("color-selector-sliders-saturation"),
+                    Loc.GetString("color-selector-sliders-value")
+                );
+        }
+
+        return ("ERR", "ERR", "ERR");
+    }
+
+    private float GetColorValueDivisor(ColorSliderOrder order)
+    {
+        if (order == ColorSliderOrder.Alpha)
+        {
+            return 100.0f;
+        }
+
+        switch (SelectorType)
+        {
+            case ColorSelectorType.Rgb:
+                return 255.0f;
+            case ColorSelectorType.Hsv:
+                switch (order)
+                {
+                    case ColorSliderOrder.Top:
+                        return 360.0f;
+                    default:
+                        return 100.0f;
+                }
+        }
+
+        return 0.0f;
+    }
+
+    private void OnColorSet()
+    {
+        // stack overflow otherwise due to value sets
+        if (_updating)
+        {
+            return;
+        }
+
+        switch (SelectorType)
+        {
+            case ColorSelectorType.Rgb:
+                Color rgbColor = new Color(_topColorSlider.Value, _middleColorSlider.Value, _bottomColorSlider.Value, _alphaSlider.Value);
+
+                _currentColor = rgbColor;
+                Update();
+
+                OnColorChanged!(rgbColor);
+                break;
+            case ColorSelectorType.Hsv:
+                Color hsvColor = Color.FromHsv(new Vector4(_topColorSlider.Value, _middleColorSlider.Value, _bottomColorSlider.Value, _alphaSlider.Value));
+
+                _currentColor = hsvColor;
+                Update();
+
+                OnColorChanged!(hsvColor);
+                break;
+        }
+    }
+
+    private enum ColorSliderOrder
+    {
+        Top,
+        Middle,
+        Bottom,
+        Alpha
+    }
+
+    public enum ColorSelectorType
+    {
+        Rgb,
+        Hsv,
+    }
+}

Robust.Client/UserInterface/Controls/ColorableSlider.cs

@@ -0,0 +1,81 @@
+using Robust.Client.Graphics;
+using Robust.Shared.Maths;
+using Robust.Shared.Log;
+
+namespace Robust.Client.UserInterface.Controls;
+
+public sealed class ColorableSlider : Slider
+{
+    public const string StylePropertyFillWhite = "fillWhite"; // needs to be filled with white
+    public const string StylePropertyBackgroundWhite = "backgroundWhite"; // also needs to be filled with white
+
+    public Color Color { get; private set; } = Color.White;
+    public PartSelector Part
+    {
+        get => _currentPartSelector;
+        set
+        {
+            _currentPartSelector = value;
+
+            UpdateStyleBoxes();
+        }
+    }
+
+    private PartSelector _currentPartSelector = PartSelector.Background;
+
+    public void SetColor(Color color)
+    {
+        Color = color;
+        switch (Part)
+        {
+            case PartSelector.Fill:
+                _fillPanel.Modulate = Color;
+                break;
+            case PartSelector.Background:
+                _backgroundPanel.Modulate = Color;
+                break;
+        }
+    }
+
+    protected override void UpdateStyleBoxes()
+    {
+        StyleBox? GetStyleBox(string name)
+        {
+            if (TryGetStyleProperty<StyleBox>(name, out var box))
+            {
+                return box;
+            }
+
+            return null;
+        }
+
+        string backBox = StylePropertyBackground;
+        string fillBox = StylePropertyFill;
+
+        switch (Part)
+        {
+            case PartSelector.Fill:
+                fillBox = StylePropertyFillWhite;
+                _fillPanel.Modulate = Color;
+
+                break;
+            case PartSelector.Background:
+                backBox = StylePropertyBackgroundWhite;
+
+                _fillPanel.Modulate = Color.Transparent; // make this transparent
+                _backgroundPanel.Modulate = Color;
+                break;
+        }
+
+        _backgroundPanel.PanelOverride = BackgroundStyleBoxOverride ?? GetStyleBox(backBox);
+        _foregroundPanel.PanelOverride = ForegroundStyleBoxOverride ?? GetStyleBox(StylePropertyForeground);
+        _fillPanel.PanelOverride = FillStyleBoxOverride ?? GetStyleBox(fillBox);
+        _grabber.PanelOverride = GrabberStyleBoxOverride ?? GetStyleBox(StylePropertyGrabber);
+    }
+
+    public enum PartSelector
+    {
+        Fill,
+        Background
+    }
+}

Robust.Client/UserInterface/Controls/LineEdit.cs

@@ -65,18 +65,22 @@ namespace Robust.Client.UserInterface.Controls
             get => _text;
             set
             {
-                if (value == null)
-                {
-                    value = "";
-                }
+                // Save cursor position or -1 for end
+                var cursorTarget = CursorPosition == Text.Length ? -1 : CursorPosition;
 
-                if (!SetText(value))
+                if (!InternalSetText(value))
                 {
                     return;
                 }
 
-                _cursorPosition = 0;
-                _selectionStart = 0;
+                var clamped = MathHelper.Clamp(cursorTarget == -1 ? _text.Length : cursorTarget, 0, _text.Length);
+                while (clamped < _text.Length && !Rune.TryGetRuneAt(_text, clamped, out _))
+                {
+                    clamped++;
+                }
+
+                _cursorPosition = clamped;
+                _selectionStart = _cursorPosition;
                 _updatePseudoClass();
             }
         }
@@ -203,7 +207,7 @@ namespace Robust.Client.UserInterface.Controls
             var lower = SelectionLower;
             var newContents = Text[..lower] + text + Text[SelectionUpper..];
 
-            if (!SetText(newContents))
+            if (!InternalSetText(newContents))
             {
                 return;
             }
@@ -216,7 +220,7 @@ namespace Robust.Client.UserInterface.Controls
         /// <remarks>
         /// Does not fix cursor positions, those will have to be adjusted manually.
         /// </remarks>>
-        protected bool SetText(string newText)
+        private bool InternalSetText(string newText)
         {
             if (IsValid != null && !IsValid(newText))
             {

Robust.Client/UserInterface/Controls/Slider.cs

@@ -13,10 +13,10 @@ namespace Robust.Client.UserInterface.Controls
         public const string StylePropertyFill = "fill";
         public const string StylePropertyGrabber = "grabber";
 
-        private readonly PanelContainer _foregroundPanel;
-        private readonly PanelContainer _backgroundPanel;
-        private readonly PanelContainer _fillPanel;
-        private readonly PanelContainer _grabber;
+        protected readonly PanelContainer _foregroundPanel;
+        protected readonly PanelContainer _backgroundPanel;
+        protected readonly PanelContainer _fillPanel;
+        protected readonly PanelContainer _grabber;
 
         private bool _grabbed;
 
@@ -169,7 +169,7 @@ namespace Robust.Client.UserInterface.Controls
             UpdateStyleBoxes();
         }
 
-        private void UpdateStyleBoxes()
+        protected virtual void UpdateStyleBoxes()
         {
             StyleBox? GetStyleBox(string name)
             {
@@ -182,7 +182,7 @@ namespace Robust.Client.UserInterface.Controls
             }
 
             _backgroundPanel.PanelOverride = BackgroundStyleBoxOverride ?? GetStyleBox(StylePropertyBackground);
-            _foregroundPanel.PanelOverride = BackgroundStyleBoxOverride ?? GetStyleBox(StylePropertyForeground);
+            _foregroundPanel.PanelOverride = ForegroundStyleBoxOverride ?? GetStyleBox(StylePropertyForeground);
             _fillPanel.PanelOverride = FillStyleBoxOverride ?? GetStyleBox(StylePropertyFill);
             _grabber.PanelOverride = GrabberStyleBoxOverride ?? GetStyleBox(StylePropertyGrabber);
         }

Robust.Client/UserInterface/CustomControls/EntitySpawnWindow.cs

@@ -228,7 +228,7 @@ namespace Robust.Client.UserInterface.CustomControls
 
             foreach (var prototype in prototypeManager.EnumeratePrototypes<EntityPrototype>())
             {
-                if (prototype.Abstract)
+                if (prototype.NoSpawn || prototype.Abstract)
                 {
                     continue;
                 }

Robust.Client/ViewVariables/Instances/ViewVariablesInstanceEntity.cs

@@ -142,7 +142,7 @@ namespace Robust.Client.ViewVariables.Instances
             {
                 ViewVariablesTraitMembers.CreateMemberGroupHeader(
                     ref first,
-                    TypeAbbreviation.Abbreviate(group.Key),
+                    PrettyPrint.PrintUserFacingTypeShort(group.Key, 2),
                     clientVBox);
 
                 foreach (var control in group)
@@ -206,7 +206,7 @@ namespace Robust.Client.ViewVariables.Instances
 
             foreach (var component in componentList)
             {
-                var button = new Button {Text = TypeAbbreviation.Abbreviate(component.GetType()), TextAlign = Label.AlignMode.Left};
+                var button = new Button {Text = PrettyPrint.PrintUserFacingTypeShort(component.GetType(), 2), TextAlign = Label.AlignMode.Left};
                 var removeButton = new TextureButton()
                 {
                     StyleClasses = { DefaultWindow.StyleClassWindowCloseButton },

Robust.Client/ViewVariables/Traits/ViewVariablesTraitMembers.cs

@@ -45,7 +45,7 @@ namespace Robust.Client.ViewVariables.Traits
                 {
                     CreateMemberGroupHeader(
                         ref first,
-                        TypeAbbreviation.Abbreviate(group.Key),
+                        PrettyPrint.PrintUserFacingTypeShort(group.Key, 2),
                         _memberList);
 
                     foreach (var control in group)

Robust.Client/ViewVariables/ViewVariablesInstance.cs

@@ -98,7 +98,7 @@ namespace Robust.Client.ViewVariables
                         Editable = access == VVAccess.ReadWrite,
                         Name = memberInfo.Name,
                         Type = memberType.AssemblyQualifiedName,
-                        TypePretty = TypeAbbreviation.Abbreviate(memberType),
+                        TypePretty = PrettyPrint.PrintUserFacingTypeShort(memberType, 2),
                         Value = value
                     };
 

Robust.Client/ViewVariables/ViewVariablesManager.cs

@@ -277,7 +277,7 @@ namespace Robust.Client.ViewVariables
 
         public Task<ViewVariablesRemoteSession> RequestSession(ViewVariablesObjectSelector selector)
         {
-            var msg = _netManager.CreateNetMessage<MsgViewVariablesReqSession>();
+            var msg = new MsgViewVariablesReqSession();
             msg.Selector = selector;
             msg.RequestId = _nextReqId++;
             _netManager.ClientSendMessage(msg);
@@ -293,7 +293,7 @@ namespace Robust.Client.ViewVariables
                 throw new ArgumentException("Session is closed", nameof(session));
             }
 
-            var msg = _netManager.CreateNetMessage<MsgViewVariablesReqData>();
+            var msg = new MsgViewVariablesReqData();
             var reqId = msg.RequestId = _nextReqId++;
             msg.RequestMeta = meta;
             msg.SessionId = session.SessionId;
@@ -315,7 +315,7 @@ namespace Robust.Client.ViewVariables
                 throw new ArgumentException();
             }
 
-            var closeMsg = _netManager.CreateNetMessage<MsgViewVariablesCloseSession>();
+            var closeMsg = new MsgViewVariablesCloseSession();
             closeMsg.SessionId = session.SessionId;
             _netManager.ClientSendMessage(closeMsg);
         }
@@ -332,7 +332,7 @@ namespace Robust.Client.ViewVariables
                 throw new ArgumentException();
             }
 
-            var msg = _netManager.CreateNetMessage<MsgViewVariablesModifyRemote>();
+            var msg = new MsgViewVariablesModifyRemote();
             msg.SessionId = session.SessionId;
             msg.ReinterpretValue = reinterpretValue;
             msg.PropertyIndex = propertyIndex;

Robust.Server/BaseServer.cs

@@ -31,6 +31,7 @@ using Robust.Shared.Network;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager;
+using Robust.Shared.Threading;
 using Robust.Shared.Timing;
 using Robust.Shared.Utility;
 using Serilog.Debugging;
@@ -87,6 +88,7 @@ namespace Robust.Server
         [Dependency] private readonly ILocalizationManagerInternal _loc = default!;
         [Dependency] private readonly INetConfigurationManager _netCfgMan = default!;
         [Dependency] private readonly IServerConsoleHost _consoleHost = default!;
+        [Dependency] private readonly IParallelManagerInternal _parallelMgr = default!;
 
         private readonly Stopwatch _uptimeStopwatch = new();
 
@@ -184,6 +186,8 @@ namespace Robust.Server
 
             ProfileOptSetup.Setup(_config);
 
+            _parallelMgr.Initialize();
+
             //Sets up Logging
             _logHandlerFactory = logHandlerFactory;
 
@@ -338,7 +342,7 @@ namespace Robust.Server
             var prototypeManager = IoCManager.Resolve<IPrototypeManager>();
             prototypeManager.Initialize();
             prototypeManager.LoadDirectory(Options.PrototypeDirectory);
-            prototypeManager.Resync();
+            prototypeManager.ResolveResults();
 
             _consoleHost.Initialize();
             _entityManager.Startup();

Robust.Server/Bql/BqlQuerySelector.Builtin.cs

@@ -312,15 +312,20 @@ namespace Robust.Server.Bql
         {
             var radius = (float)(double)arguments[0];
             var entityLookup = EntitySystem.Get<EntityLookupSystem>();
+            var xformQuery = IoCManager.Resolve<IEntityManager>().GetEntityQuery<TransformComponent>();
+            var distinct = new HashSet<EntityUid>();
+
+            foreach (var uid in input)
+            {
+                foreach (var near in entityLookup.GetEntitiesInRange(xformQuery.GetComponent(uid).Coordinates,
+                             radius))
+                {
+                    if (!distinct.Add(near)) continue;
+                    yield return near;
+                }
+            }
 
-            // TODO: Make this a foreach and reduce LINQ chain because it'll allocate a LOT
             //BUG: GetEntitiesInRange effectively uses manhattan distance. This is not intended, near is supposed to be circular.
-            return input.Where(entityManager.HasComponent<TransformComponent>)
-                .SelectMany(e =>
-                    entityLookup.GetEntitiesInRange(entityManager.GetComponent<TransformComponent>(e).Coordinates,
-                        radius))
-                .Select(x => x) // Sloth's fault.
-                .Distinct();
         }
     }
 

Robust.Server/Console/Commands/MapCommands.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Globalization;
 using System.Linq;
 using System.Text;
@@ -114,17 +115,19 @@ namespace Robust.Server.Console.Commands
     {
         public string Command => "loadbp";
         public string Description => "Loads a blueprint from disk into the game.";
-        public string Help => "loadbp <MapID> <Path> [storeUids]";
+        public string Help => "loadbp <MapID> <Path> [storeUids] [x y] [rotation]";
 
         public void Execute(IConsoleShell shell, string argStr, string[] args)
         {
-            if (args.Length < 2)
+            if (args.Length != 2 && args.Length != 3 && args.Length != 5 && args.Length != 6)
             {
+                shell.WriteError("Must have either 2, 3, 5, or 6 arguments.");
                 return;
             }
 
             if (!int.TryParse(args[0], out var intMapId))
             {
+                shell.WriteError($"{args[0]} is not a valid integer.");
                 return;
             }
 
@@ -147,7 +150,41 @@ namespace Robust.Server.Console.Commands
             var loadOptions = new MapLoadOptions();
             if (args.Length > 2)
             {
-                loadOptions.StoreMapUids = bool.Parse(args[2]);
+                if (!Boolean.TryParse(args[2], out var storeUids))
+                {
+                    shell.WriteError($"{args[2]} is not a valid boolean..");
+                    return;
+                }
+
+                loadOptions.StoreMapUids = storeUids;
+            }
+
+            if (args.Length >= 5)
+            {
+                if (!int.TryParse(args[3], out var x))
+                {
+                    shell.WriteError($"{args[3]} is not a valid integer.");
+                    return;
+                }
+
+                if (!int.TryParse(args[4], out var y))
+                {
+                    shell.WriteError($"{args[4]} is not a valid integer.");
+                    return;
+                }
+
+                loadOptions.Offset = new Vector2(x, y);
+            }
+
+            if (args.Length == 6)
+            {
+                if (!float.TryParse(args[5], out var rotation))
+                {
+                    shell.WriteError($"{args[5]} is not a valid integer.");
+                    return;
+                }
+
+                loadOptions.Rotation = new Angle(rotation);
             }
 
             var mapLoader = IoCManager.Resolve<IMapLoader>();
@@ -191,15 +228,20 @@ namespace Robust.Server.Console.Commands
     {
         public string Command => "loadmap";
         public string Description => "Loads a map from disk into the game.";
-        public string Help => "loadmap <MapID> <Path>";
+        public string Help => "loadmap <MapID> <Path> [x y] [rotation]";
 
         public void Execute(IConsoleShell shell, string argStr, string[] args)
         {
-            if (args.Length < 1)
-                return;
+            if (args.Length != 2 && args.Length != 4 && args.Length != 5)
+            {
+                shell.WriteError($"Must have either 2, 4, or 5 arguments.");
+            }
 
             if (!int.TryParse(args[0], out var intMapId))
+            {
+                shell.WriteError($"{args[0]} is not a valid integer.");
                 return;
+            }
 
             var mapId = new MapId(intMapId);
 
@@ -217,7 +259,36 @@ namespace Robust.Server.Console.Commands
                 return;
             }
 
-            IoCManager.Resolve<IMapLoader>().LoadMap(mapId, args[1]);
+            var loadOptions = new MapLoadOptions();
+
+            if (args.Length >= 3)
+            {
+                if (!int.TryParse(args[2], out var x))
+                {
+                    shell.WriteError($"{args[2]} is not a valid integer.");
+                    return;
+                }
+
+                if (!int.TryParse(args[3], out var y))
+                {
+                    shell.WriteError($"{args[3]} is not a valid integer.");
+                    return;
+                }
+                loadOptions.Offset = new Vector2(x, y);
+            }
+
+            if (args.Length == 4)
+            {
+                if (!float.TryParse(args[4], out var rotation))
+                {
+                    shell.WriteError($"{args[4]} is not a valid integer.");
+                    return;
+                }
+
+                loadOptions.Rotation = new Angle(rotation);
+            }
+
+            IoCManager.Resolve<IMapLoader>().LoadMap(mapId, args[1], loadOptions);
 
             if (mapManager.MapExists(mapId))
                 shell.WriteLine($"Map {mapId} has been loaded from {args[1]}.");

Robust.Server/Console/ServerConsoleHost.cs

@@ -33,7 +33,7 @@ namespace Robust.Server.Console
             if (!NetManager.IsConnected || session is null)
                 return;
 
-            var msg = NetManager.CreateNetMessage<MsgConCmd>();
+            var msg = new MsgConCmd();
             msg.Text = command;
             NetManager.ServerSendMessage(msg, ((IPlayerSession)session).ConnectedClient);
         }
@@ -121,7 +121,7 @@ namespace Robust.Server.Console
         private void HandleRegistrationRequest(INetChannel senderConnection)
         {
             var netMgr = IoCManager.Resolve<IServerNetManager>();
-            var message = netMgr.CreateNetMessage<MsgConCmdReg>();
+            var message = new MsgConCmdReg();
 
             var counter = 0;
             message.Commands = new MsgConCmdReg.Command[RegisteredCommands.Count];
@@ -154,7 +154,7 @@ namespace Robust.Server.Console
         {
             if (session != null)
             {
-                var replyMsg = NetManager.CreateNetMessage<MsgConCmdAck>();
+                var replyMsg = new MsgConCmdAck();
                 replyMsg.Error = error;
                 replyMsg.Text = text;
                 NetManager.ServerSendMessage(replyMsg, session.ConnectedClient);

Robust.Server/DataMetrics/MetricsManager.MetricsServer.cs

@@ -3,7 +3,7 @@ using System.IO;
 using System.IO.Compression;
 using System.Threading;
 using System.Threading.Tasks;
-using ManagedHttpListener;
+using SpaceWizards.HttpListener;
 using Prometheus;
 using Robust.Shared.Log;
 

Robust.Server/GameObjects/Components/UserInterface/ServerUserInterfaceComponent.cs

@@ -184,6 +184,7 @@ namespace Robust.Server.GameObjects
             }
 
             _subscribedSessions.Add(session);
+            IoCManager.Resolve<IEntityManager>().EventBus.RaiseLocalEvent(Owner.Owner, new BoundUIOpenedEvent(UiKey, Owner.Owner, session));
             SendMessage(new OpenBoundInterfaceMessage(), session);
             if (_lastState != null)
             {
@@ -236,11 +237,11 @@ namespace Robust.Server.GameObjects
         public void CloseShared(IPlayerSession session)
         {
             var owner = Owner.Owner;
-            IoCManager.Resolve<IEntityManager>().EventBus.RaiseLocalEvent(owner, new BoundUIClosedEvent(UiKey, owner, session));
             OnClosed?.Invoke(session);
             _subscribedSessions.Remove(session);
             _playerStateOverrides.Remove(session);
             session.PlayerStatusChanged -= OnSessionOnPlayerStatusChanged;
+            IoCManager.Resolve<IEntityManager>().EventBus.RaiseLocalEvent(owner, new BoundUIClosedEvent(UiKey, owner, session));
 
             if (_subscribedSessions.Count == 0)
             {

Robust.Server/GameObjects/ServerEntityManager.cs

@@ -206,7 +206,7 @@ namespace Robust.Server.GameObjects
         /// <inheritdoc />
         public void SendSystemNetworkMessage(EntityEventArgs message)
         {
-            var newMsg = _networkManager.CreateNetMessage<MsgEntity>();
+            var newMsg = new MsgEntity();
             newMsg.Type = EntityMessageType.SystemMessage;
             newMsg.SystemMessage = message;
             newMsg.SourceTick = _gameTiming.CurTick;
@@ -217,7 +217,7 @@ namespace Robust.Server.GameObjects
         /// <inheritdoc />
         public void SendSystemNetworkMessage(EntityEventArgs message, INetChannel targetConnection)
         {
-            var newMsg = _networkManager.CreateNetMessage<MsgEntity>();
+            var newMsg = new MsgEntity();
             newMsg.Type = EntityMessageType.SystemMessage;
             newMsg.SystemMessage = message;
             newMsg.SourceTick = _gameTiming.CurTick;

Robust.Server/GameStates/PVSOverrideSystem.cs

@@ -0,0 +1,41 @@
+using Robust.Shared.GameObjects;
+using Robust.Shared.Players;
+
+namespace Robust.Server.GameStates;
+
+/// <summary>
+///     Placeholder system to expose some parts of the internal <see cref="PVSSystem"/> that allows entities to ignore
+///     normal PVS rules, such that they are always sent to clients.
+/// </summary>
+public sealed partial class PVSOverrideSystem : EntitySystem
+{
+    [Shared.IoC.Dependency] private readonly PVSSystem _pvs = default!;
+
+    /// <summary>
+    ///     Used to ensure that an entity is always sent to every client. Overrides any client-specific overrides.
+    /// </summary>
+    public void AddGlobalOverride(EntityUid uid)
+    {
+        _pvs.EntityPVSCollection.UpdateIndex(uid, true);
+    }
+
+    /// <summary>
+    ///     Used to ensure that an entity is always sent to a specific client. Overrides any global or pre-existing
+    ///     client-specific overrides.
+    /// </summary>
+    public void AddSessionOverride(EntityUid uid, ICommonSession session)
+    {
+        _pvs.EntityPVSCollection.UpdateIndex(uid, session, true);
+    }
+
+    /// <summary>
+    ///     Removes any global or client-specific overrides.
+    /// </summary>
+    public void ClearOverride(EntityUid uid, TransformComponent? xform = null)
+    {
+        if (!Resolve(uid, ref xform))
+            return;
+
+        _pvs.EntityPVSCollection.UpdateIndex(uid, xform.Coordinates, true);
+    }
+}

Robust.Server/GameStates/PVSSystem.cs

@@ -83,11 +83,11 @@ internal sealed partial class PVSSystem : EntitySystem
 
     private readonly ObjectPool<Dictionary<MapChunkLocation, int>> _mapChunkPool =
         new DefaultObjectPool<Dictionary<MapChunkLocation, int>>(
-            new ChunkPoolPolicy<MapChunkLocation>(), 256);
+            new ChunkPoolPolicy<MapChunkLocation>(), MaxVisPoolSize);
 
     private readonly ObjectPool<Dictionary<GridChunkLocation, int>> _gridChunkPool =
         new DefaultObjectPool<Dictionary<GridChunkLocation, int>>(
-            new ChunkPoolPolicy<GridChunkLocation>(), 256);
+            new ChunkPoolPolicy<GridChunkLocation>(), MaxVisPoolSize);
 
     private readonly Dictionary<uint, Dictionary<MapChunkLocation, int>> _mapIndices = new(4);
     private readonly Dictionary<uint, Dictionary<GridChunkLocation, int>> _gridIndices = new(4);
@@ -352,6 +352,8 @@ internal sealed partial class PVSSystem : EntitySystem
             {
                 var (viewPos, range, mapId) = CalcViewBounds(in eyeEuid, transformQuery);
 
+                if(mapId == MapId.Nullspace) continue;
+
                 uint visMask = EyeComponent.DefaultVisibilityMask;
                 if (eyeQuery.TryGetComponent(eyeEuid, out var eyeComp))
                     visMask = eyeComp.VisibilityMask;
@@ -544,7 +546,7 @@ internal sealed partial class PVSSystem : EntitySystem
             !AddToChunkSetRecursively(in parent, visMask, tree, set, transform, metadata)) //did we just fail to add the parent?
             return false; //we failed? suppose we dont get added either
 
-        //todo paul i want it to crash here if it gets added double bc that shouldnt happen and will add alot of unneeded cycles, make this a simpl assignment at some point maybe idk
+        //i want it to crash here if it gets added double bc that shouldnt happen and will add alot of unneeded cycles
         tree.Set(uid, parent);
         set.Add(uid, mComp);
         return true;
@@ -601,6 +603,14 @@ internal sealed partial class PVSSystem : EntitySystem
                 ref entitiesSent, mQuery, tQuery, in enteredEntityBudget, in newEntityBudget);
         }
 
+        var expandEvent = new ExpandPvsEvent(session, new List<EntityUid>());
+        RaiseLocalEvent(ref expandEvent);
+        foreach (var entityUid in expandEvent.Entities)
+        {
+            RecursivelyAddOverride(in entityUid, seenSet, playerVisibleSet, visibleEnts, fromTick, ref newEntitiesSent,
+                ref entitiesSent, mQuery, tQuery, in enteredEntityBudget, in newEntityBudget);
+        }
+
         var entityStates = new List<EntityState>();
 
         foreach (var (entityUid, visiblity) in visibleEnts)
@@ -629,7 +639,7 @@ internal sealed partial class PVSSystem : EntitySystem
 
             entityStates.Add(new EntityState(entityUid, new NetListAsArray<ComponentChange>(new []
             {
-                ComponentChange.Changed(_stateManager.TransformNetId, new TransformComponent.TransformComponentState(Vector2.Zero, Angle.Zero, EntityUid.Invalid, false, false)),
+                ComponentChange.Changed(_stateManager.TransformNetId, new TransformComponentState(Vector2.Zero, Angle.Zero, EntityUid.Invalid, false, false)),
             }), true));
         }
 

Robust.Server/GameStates/ServerGameStateManager.cs

@@ -1,15 +1,14 @@
 using System;
 using System.Buffers;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using JetBrains.Annotations;
-using Microsoft.CodeAnalysis;
-using Microsoft.Extensions.ObjectPool;
 using Robust.Server.GameObjects;
 using Robust.Server.Player;
+using Robust.Shared;
+using Robust.Shared.Configuration;
 using Robust.Shared.Enums;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameStates;
@@ -18,8 +17,10 @@ using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Network;
 using Robust.Shared.Network.Messages;
+using Robust.Shared.Threading;
 using Robust.Shared.Timing;
 using Robust.Shared.Utility;
+using SharpZstd.Interop;
 
 namespace Robust.Server.GameStates
 {
@@ -40,9 +41,13 @@ namespace Robust.Server.GameStates
         [Dependency] private readonly INetworkedMapManager _mapManager = default!;
         [Dependency] private readonly IEntitySystemManager _systemManager = default!;
         [Dependency] private readonly IServerEntityNetworkManager _entityNetworkManager = default!;
+        [Dependency] private readonly IConfigurationManager _cfg = default!;
+        [Dependency] private readonly IParallelManager _parallelMgr = default!;
 
         private ISawmill _logger = default!;
 
+        private PvsThreadResources[] _threadResourcesPool = Array.Empty<PvsThreadResources>();
+
         public ushort TransformNetId { get; set; }
 
         public void PostInject()
@@ -60,6 +65,43 @@ namespace Robust.Server.GameStates
             _networkManager.Disconnect += HandleClientDisconnect;
 
             _pvs = EntitySystem.Get<PVSSystem>();
+
+            _parallelMgr.AddAndInvokeParallelCountChanged(ParallelChanged);
+
+            _cfg.OnValueChanged(CVars.NetPVSCompressLevel, _ => UpdateZStdParams(), true);
+        }
+
+        private void ParallelChanged()
+        {
+            foreach (var resource in _threadResourcesPool)
+            {
+                resource.CompressionContext.Dispose();
+            }
+
+            _threadResourcesPool = new PvsThreadResources[_parallelMgr.ParallelProcessCount];
+            for (var i = 0; i < _threadResourcesPool.Length; i++)
+            {
+                ref var res = ref _threadResourcesPool[i];
+                res.CompressionContext = new ZStdCompressionContext();
+            }
+
+            UpdateZStdParams();
+        }
+
+        private void UpdateZStdParams()
+        {
+            var compressionLevel = _cfg.GetCVar(CVars.NetPVSCompressLevel);
+
+            for (var i = 0; i < _threadResourcesPool.Length; i++)
+            {
+                ref var res = ref _threadResourcesPool[i];
+                res.CompressionContext.SetParameter(ZSTD_cParameter.ZSTD_c_compressionLevel, compressionLevel);
+            }
+        }
+
+        private struct PvsThreadResources
+        {
+            public ZStdCompressionContext CompressionContext;
         }
 
         private void HandleClientConnected(object? sender, NetChannelArgs e)
@@ -142,7 +184,7 @@ namespace Robust.Server.GameStates
                 (chunks, playerChunks, viewerEntities) = _pvs.GetChunks(players);
                 const int ChunkBatchSize = 2;
                 var chunksCount = chunks.Count;
-                var chunkBatches = (int) MathF.Ceiling((float) chunksCount / ChunkBatchSize);
+                var chunkBatches = (int)MathF.Ceiling((float)chunksCount / ChunkBatchSize);
                 chunkCache =
                     new (Dictionary<EntityUid, MetaDataComponent> metadata, RobustTree<EntityUid> tree)?[chunksCount];
 
@@ -159,7 +201,8 @@ namespace Robust.Server.GameStates
                     for (var j = start; j < end; ++j)
                     {
                         var (visMask, chunkIndexLocation) = chunks[j];
-                        reuse[j] = _pvs.TryCalculateChunk(chunkIndexLocation, visMask, transformQuery, metadataQuery, out var chunk);
+                        reuse[j] = _pvs.TryCalculateChunk(chunkIndexLocation, visMask, transformQuery, metadataQuery,
+                            out var chunk);
                         chunkCache[j] = chunk;
                     }
                 });
@@ -168,33 +211,27 @@ namespace Robust.Server.GameStates
                 ArrayPool<bool>.Shared.Return(reuse);
             }
 
-            const int BatchSize = 2;
-            var batches = (int) MathF.Ceiling((float) players.Length / BatchSize);
-
-            Parallel.For(0, batches, i =>
-            {
-                var start = i * BatchSize;
-                var end = Math.Min(start + BatchSize, players.Length);
-
-                for (var j = start; j < end; ++j)
+            _parallelMgr.ParallelForWithResources(
+                0, players.Length,
+                _threadResourcesPool,
+                (int i, ref PvsThreadResources resource) =>
                 {
                     try
                     {
-                        SendStateUpdate(j);
+                        SendStateUpdate(i, ref resource);
                     }
                     catch (Exception e) // Catch EVERY exception
                     {
                         _logger.Log(LogLevel.Error, e, "Caught exception while generating mail.");
                     }
-                }
-            });
+                });
 
-            void SendStateUpdate(int sessionIndex)
+            void SendStateUpdate(int sessionIndex, ref PvsThreadResources resources)
             {
                 var session = players[sessionIndex];
 
                 // KILL IT WITH FIRE
-                if(mainThread != Thread.CurrentThread)
+                if (mainThread != Thread.CurrentThread)
                     IoCManager.InitThread(new DependencyCollection(parentDeps), true);
 
                 var channel = session.ConnectedClient;
@@ -214,13 +251,15 @@ namespace Robust.Server.GameStates
                 // lastAck varies with each client based on lag and such, we can't just make 1 global state and send it to everyone
                 var lastInputCommand = inputSystem.GetLastInputCommand(session);
                 var lastSystemMessage = _entityNetworkManager.GetLastMessageSequence(session);
-                var state = new GameState(lastAck, _gameTiming.CurTick, Math.Max(lastInputCommand, lastSystemMessage), entStates, playerStates, deletions, mapData);
+                var state = new GameState(lastAck, _gameTiming.CurTick, Math.Max(lastInputCommand, lastSystemMessage),
+                    entStates, playerStates, deletions, mapData);
 
                 InterlockedHelper.Min(ref oldestAckValue, lastAck.Value);
 
                 // actually send the state
-                var stateUpdateMessage = _networkManager.CreateNetMessage<MsgState>();
+                var stateUpdateMessage = new MsgState();
                 stateUpdateMessage.State = state;
+                stateUpdateMessage.CompressionContext = resources.CompressionContext;
 
                 // If the state is too big we let Lidgren send it reliably.
                 // This is to avoid a situation where a state is so large that it consistently gets dropped
@@ -238,7 +277,7 @@ namespace Robust.Server.GameStates
                 _networkManager.ServerSendMessage(stateUpdateMessage, channel);
             }
 
-            if(_pvs.CullingEnabled)
+            if (_pvs.CullingEnabled)
                 _pvs.ReturnToPool(playerChunks);
             _pvs.Cleanup(_playerManager.ServerSessions);
             var oldestAck = new GameTick(oldestAckValue);

Robust.Server/Maps/GridSerializer.cs

@@ -0,0 +1,218 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+using Robust.Shared.Serialization.Manager;
+using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.Serialization.Markdown;
+using Robust.Shared.Serialization.Markdown.Mapping;
+using Robust.Shared.Serialization.Markdown.Sequence;
+using Robust.Shared.Serialization.Markdown.Validation;
+using Robust.Shared.Serialization.Markdown.Value;
+using Robust.Shared.Serialization.TypeSerializers.Interfaces;
+
+namespace Robust.Server.Maps
+{
+    [TypeSerializer]
+    internal sealed class MapChunkSerializer : ITypeSerializer<MapChunk, MappingDataNode>
+    {
+        public ValidationNode Validate(ISerializationManager serializationManager, MappingDataNode node,
+            IDependencyCollection dependencies, ISerializationContext? context = null)
+        {
+            throw new NotImplementedException();
+        }
+
+        public MapChunk Read(ISerializationManager serializationManager, MappingDataNode node,
+            IDependencyCollection dependencies, bool skipHook, ISerializationContext? context = null, MapChunk? chunk = null)
+        {
+            var tileNode = (ValueDataNode)node["tiles"];
+            var tileBytes = Convert.FromBase64String(tileNode.Value);
+
+            using var stream = new MemoryStream(tileBytes);
+            using var reader = new BinaryReader(stream);
+
+            var mapManager = dependencies.Resolve<IMapManager>();
+            mapManager.SuppressOnTileChanged = true;
+
+            if (chunk == null)
+            {
+                throw new InvalidOperationException(
+                    $"Someone tried deserializing a gridchunk without passing a value.");
+            }
+
+            if (context is not MapLoader.MapContext mapContext)
+            {
+                throw new InvalidOperationException(
+                    $"Someone tried serializing a gridchunk without passing {nameof(MapLoader.MapContext)} as context.");
+            }
+
+            var tileMap = mapContext.TileMap;
+
+            if (tileMap == null)
+            {
+                throw new InvalidOperationException(
+                    $"Someone tried deserializing a gridchunk before deserializing the tileMap.");
+            }
+
+            chunk.SuppressCollisionRegeneration = true;
+
+            var tileDefinitionManager = dependencies.Resolve<ITileDefinitionManager>();
+
+            for (ushort y = 0; y < chunk.ChunkSize; y++)
+            {
+                for (ushort x = 0; x < chunk.ChunkSize; x++)
+                {
+                    var id = reader.ReadUInt16();
+                    var flags = (TileRenderFlag)reader.ReadByte();
+                    var variant = reader.ReadByte();
+
+                    var defName = tileMap[id];
+                    id = tileDefinitionManager[defName].TileId;
+
+                    var tile = new Tile(id, flags, variant);
+                    chunk.SetTile(x, y, tile);
+                }
+            }
+
+            chunk.SuppressCollisionRegeneration = false;
+            mapManager.SuppressOnTileChanged = false;
+
+            return chunk;
+        }
+
+        public DataNode Write(ISerializationManager serializationManager, MapChunk value, bool alwaysWrite = false,
+            ISerializationContext? context = null)
+        {
+            var root = new MappingDataNode();
+            var ind = new ValueDataNode($"{value.X},{value.Y}");
+            root.Add("ind", ind);
+
+            var gridNode = new ValueDataNode();
+            root.Add("tiles", gridNode);
+
+            gridNode.Value = SerializeTiles(value);
+
+            return root;
+        }
+
+        private static string SerializeTiles(MapChunk chunk)
+        {
+            // number of bytes written per tile, because sizeof(Tile) is useless.
+            const int structSize = 4;
+
+            var nTiles = chunk.ChunkSize * chunk.ChunkSize * structSize;
+            var barr = new byte[nTiles];
+
+            using (var stream = new MemoryStream(barr))
+            using (var writer = new BinaryWriter(stream))
+            {
+                for (ushort y = 0; y < chunk.ChunkSize; y++)
+                {
+                    for (ushort x = 0; x < chunk.ChunkSize; x++)
+                    {
+                        var tile = chunk.GetTile(x, y);
+                        writer.Write(tile.TypeId);
+                        writer.Write((byte)tile.Flags);
+                        writer.Write(tile.Variant);
+                    }
+                }
+            }
+
+            return Convert.ToBase64String(barr);
+        }
+
+        public MapChunk Copy(ISerializationManager serializationManager, MapChunk source, MapChunk target, bool skipHook,
+            ISerializationContext? context = null)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    //todo paul make this be used
+    [TypeSerializer]
+    internal sealed class GridSerializer : ITypeSerializer<MapGrid, MappingDataNode>
+    {
+
+        public ValidationNode Validate(ISerializationManager serializationManager, MappingDataNode node,
+            IDependencyCollection dependencies, ISerializationContext? context = null)
+        {
+            throw new NotImplementedException();
+        }
+
+        public MapGrid Read(ISerializationManager serializationManager, MappingDataNode node,
+            IDependencyCollection dependencies, bool skipHook, ISerializationContext? context = null, MapGrid? grid = null)
+        {
+            var info = node.Get<MappingDataNode>("settings");
+            var chunks = node.Get<SequenceDataNode>("chunks");
+            ushort csz = 0;
+            ushort tsz = 0;
+            float sgsz = 0.0f;
+
+            foreach (var kvInfo in info.Cast<KeyValuePair<ValueDataNode, ValueDataNode>>())
+            {
+                var key = kvInfo.Key.Value;
+                var val = kvInfo.Value.Value;
+                if (key == "chunksize")
+                    csz = ushort.Parse(val);
+                else if (key == "tilesize")
+                    tsz = ushort.Parse(val);
+                else if (key == "snapsize")
+                    sgsz = float.Parse(val, CultureInfo.InvariantCulture);
+            }
+
+            //TODO: Pass in options
+            if (context is not MapLoader.MapContext mapContext)
+            {
+                throw new InvalidOperationException(
+                    $"Someone tried serializing a mapgrid without passing {nameof(MapLoader.MapContext)} as context.");
+            }
+
+            if (grid == null) throw new NotImplementedException();
+            //todo paul grid ??= dependencies.Resolve<MapManager>().CreateUnboundGrid(mapContext.TargetMap);
+
+            foreach (var chunkNode in chunks.Cast<MappingDataNode>())
+            {
+                var (chunkOffsetX, chunkOffsetY) =
+                    serializationManager.Read<Vector2i>(chunkNode["ind"], context, skipHook);
+                var chunk = grid.GetChunk(chunkOffsetX, chunkOffsetY);
+                serializationManager.Read(typeof(MapChunkSerializer), chunkNode, context, skipHook, chunk);
+            }
+
+            return grid;
+        }
+
+        public DataNode Write(ISerializationManager serializationManager, MapGrid value, bool alwaysWrite = false,
+            ISerializationContext? context = null)
+        {
+            var gridn = new MappingDataNode();
+            var info = new MappingDataNode();
+            var chunkSeq = new SequenceDataNode();
+
+            gridn.Add("settings", info);
+            gridn.Add("chunks", chunkSeq);
+
+            info.Add("chunksize", value.ChunkSize.ToString(CultureInfo.InvariantCulture));
+            info.Add("tilesize", value.TileSize.ToString(CultureInfo.InvariantCulture));
+
+            var chunks = value.GetMapChunks();
+            foreach (var chunk in chunks)
+            {
+                var chunkNode = serializationManager.WriteValue(chunk.Value);
+                chunkSeq.Add(chunkNode);
+            }
+
+            return gridn;
+        }
+
+        public MapGrid Copy(ISerializationManager serializationManager, MapGrid source, MapGrid target, bool skipHook,
+            ISerializationContext? context = null)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

Robust.Server/Maps/IMapLoader.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using Robust.Shared.GameObjects;
 using Robust.Shared.Map;
 using YamlDotNet.RepresentationModel;
 
@@ -6,12 +8,12 @@ namespace Robust.Server.Maps
 {
     public interface IMapLoader
     {
-        IMapGrid? LoadBlueprint(MapId mapId, string path);
-        IMapGrid? LoadBlueprint(MapId mapId, string path, MapLoadOptions options);
+        (IReadOnlyList<EntityUid> entities, GridId? gridId) LoadBlueprint(MapId mapId, string path);
+        (IReadOnlyList<EntityUid> entities, GridId? gridId) LoadBlueprint(MapId mapId, string path, MapLoadOptions options);
         void SaveBlueprint(GridId gridId, string yamlPath);
 
-        void LoadMap(MapId mapId, string path);
-        void LoadMap(MapId mapId, string path, MapLoadOptions options);
+        (IReadOnlyList<EntityUid> entities, IReadOnlyList<GridId> gridIds) LoadMap(MapId mapId, string path);
+        (IReadOnlyList<EntityUid> entities, IReadOnlyList<GridId> gridIds) LoadMap(MapId mapId, string path, MapLoadOptions options);
         void SaveMap(MapId mapId, string yamlPath);
 
         event Action<YamlStream, string> LoadedMapData;

Robust.Server/Maps/MapLoadOptions.cs

@@ -1,5 +1,9 @@
-namespace Robust.Server.Maps
+using JetBrains.Annotations;
+using Robust.Shared.Maths;
+
+namespace Robust.Server.Maps
 {
+    [PublicAPI]
     public sealed class MapLoadOptions
     {
         /// <summary>
@@ -7,5 +11,38 @@
         ///     to maintain consistency upon subsequent savings.
         /// </summary>
         public bool StoreMapUids { get; set; }
+
+        /// <summary>
+        ///     Offset to apply to the loaded objects.
+        /// </summary>
+        public Vector2 Offset
+        {
+            get => _offset;
+            set
+            {
+                TransformMatrix = Matrix3.CreateTransform(value, Rotation);
+                _offset = value;
+            }
+        }
+
+        private Vector2 _offset = Vector2.Zero;
+
+        /// <summary>
+        ///     Rotation to apply to the loaded objects as a collective, around 0, 0.
+        /// </summary>
+        /// <remarks>Setting this overrides <</remarks>
+        public Angle Rotation
+        {
+            get => _rotation;
+            set
+            {
+                TransformMatrix = Matrix3.CreateTransform(Offset, value);
+                _rotation = value;
+            }
+        }
+
+        private Angle _rotation = Angle.Zero;
+
+        public Matrix3 TransformMatrix { get; set; } = Matrix3.Identity;
     }
 }

Robust.Server/Maps/MapLoader.cs

@@ -13,14 +13,15 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
+using Robust.Shared.Maths;
 using Robust.Shared.Physics;
 using Robust.Shared.Physics.Dynamics;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager;
-using Robust.Shared.Serialization.Manager.Result;
 using Robust.Shared.Serialization.Markdown;
 using Robust.Shared.Serialization.Markdown.Mapping;
+using Robust.Shared.Serialization.Markdown.Sequence;
 using Robust.Shared.Serialization.Markdown.Validation;
 using Robust.Shared.Serialization.Markdown.Value;
 using Robust.Shared.Serialization.TypeSerializers.Interfaces;
@@ -44,6 +45,7 @@ namespace Robust.Server.Maps
         [Dependency] private readonly ITileDefinitionManager _tileDefinitionManager = default!;
         [Dependency] private readonly IServerEntityManagerInternal _serverEntityManager = default!;
         [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
+        [Dependency] private readonly ISerializationManager _serializationManager = default!;
 
         public event Action<YamlStream, string>? LoadedMapData;
 
@@ -52,7 +54,7 @@ namespace Robust.Server.Maps
         {
             var grid = _mapManager.GetGrid(gridId);
 
-            var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _prototypeManager);
+            var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _prototypeManager, _serializationManager);
             context.RegisterGrid(grid);
             var root = context.Serialize();
             var document = new YamlDocument(root);
@@ -68,7 +70,7 @@ namespace Robust.Server.Maps
         }
 
         /// <inheritdoc />
-        public IMapGrid? LoadBlueprint(MapId mapId, string path)
+        public (IReadOnlyList<EntityUid> entities, GridId? gridId) LoadBlueprint(MapId mapId, string path)
         {
             return LoadBlueprint(mapId, path, DefaultLoadOptions);
         }
@@ -78,13 +80,14 @@ namespace Robust.Server.Maps
             return new ResourcePath(path).ToRootedPath();
         }
 
-        public IMapGrid? LoadBlueprint(MapId mapId, string path, MapLoadOptions options)
+        public (IReadOnlyList<EntityUid> entities, GridId? gridId) LoadBlueprint(MapId mapId, string path, MapLoadOptions options)
         {
             var resPath = Rooted(path);
 
-            if (!TryGetReader(resPath, out var reader)) return null;
+            if (!TryGetReader(resPath, out var reader)) return (Array.Empty<EntityUid>(), null);
 
-            IMapGrid grid;
+            IMapGrid? grid;
+            IReadOnlyList<EntityUid> entities;
             using (reader)
             {
                 Logger.InfoS("map", $"Loading Grid: {resPath}");
@@ -99,14 +102,15 @@ namespace Robust.Server.Maps
                 }
 
                 var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager,
-                    _prototypeManager, (YamlMappingNode) data.RootNode, mapId, options);
+                    _prototypeManager, _serializationManager, data.RootNode.ToDataNodeCast<MappingDataNode>(), mapId, options);
                 context.Deserialize();
-                grid = context.Grids[0];
+                grid = context.Grids.FirstOrDefault();
+                entities = context.Entities;
 
                 PostDeserialize(mapId, context);
             }
 
-            return grid;
+            return (entities, grid?.Index);
         }
 
         private void PostDeserialize(MapId mapId, MapContext context)
@@ -139,7 +143,7 @@ namespace Robust.Server.Maps
         public void SaveMap(MapId mapId, string yamlPath)
         {
             Logger.InfoS("map", $"Saving map {mapId} to {yamlPath}");
-            var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _prototypeManager);
+            var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager, _prototypeManager, _serializationManager);
             foreach (var grid in _mapManager.GetAllMapGrids(mapId))
             {
                 context.RegisterGrid(grid);
@@ -159,9 +163,9 @@ namespace Robust.Server.Maps
             Logger.InfoS("map", "Save completed!");
         }
 
-        public void LoadMap(MapId mapId, string path)
+        public (IReadOnlyList<EntityUid> entities, IReadOnlyList<GridId> gridIds) LoadMap(MapId mapId, string path)
         {
-            LoadMap(mapId, path, DefaultLoadOptions);
+            return LoadMap(mapId, path, DefaultLoadOptions);
         }
 
         private bool TryGetReader(ResourcePath resPath, [NotNullWhen(true)] out TextReader? reader)
@@ -191,12 +195,14 @@ namespace Robust.Server.Maps
             return true;
         }
 
-        public void LoadMap(MapId mapId, string path, MapLoadOptions options)
+        public (IReadOnlyList<EntityUid> entities, IReadOnlyList<GridId> gridIds) LoadMap(MapId mapId, string path, MapLoadOptions options)
         {
             var resPath = Rooted(path);
 
-            if (!TryGetReader(resPath, out var reader)) return;
+            if (!TryGetReader(resPath, out var reader)) return (Array.Empty<EntityUid>(), Array.Empty<GridId>());
 
+            IReadOnlyList<GridId> grids;
+            IReadOnlyList<EntityUid> entities;
             using (reader)
             {
                 Logger.InfoS("map", $"Loading Map: {resPath}");
@@ -206,17 +212,21 @@ namespace Robust.Server.Maps
                 LoadedMapData?.Invoke(data.Stream, resPath.ToString());
 
                 var context = new MapContext(_mapManager, _tileDefinitionManager, _serverEntityManager,
-                    _prototypeManager, (YamlMappingNode) data.RootNode, mapId, options);
+                    _prototypeManager, _serializationManager, data.RootNode.ToDataNodeCast<MappingDataNode>(), mapId, options);
                 context.Deserialize();
+                grids = context.Grids.Select(x => x.Index).ToArray(); // TODO: make context use grid IDs.
+                entities = context.Entities;
 
                 PostDeserialize(mapId, context);
             }
+
+            return (entities, grids);
         }
 
         /// <summary>
         ///     Handles the primary bulk of state during the map serialization process.
         /// </summary>
-        private sealed class MapContext : ISerializationContext, IEntityLoadContext,
+        internal sealed class MapContext : ISerializationContext, IEntityLoadContext,
             ITypeSerializer<GridId, ValueDataNode>,
             ITypeSerializer<EntityUid, ValueDataNode>,
             ITypeReaderWriter<EntityUid, ValueDataNode>
@@ -225,29 +235,32 @@ namespace Robust.Server.Maps
             private readonly ITileDefinitionManager _tileDefinitionManager;
             private readonly IServerEntityManagerInternal _serverEntityManager;
             private readonly IPrototypeManager _prototypeManager;
+            private readonly ISerializationManager _serializationManager;
 
             private readonly MapLoadOptions? _loadOptions;
             private readonly Dictionary<GridId, int> GridIDMap = new();
             public readonly List<MapGrid> Grids = new();
             private readonly List<GridId> _readGridIndices = new();
+            private EntityQuery<TransformComponent>? _xformQuery = null;
 
             private readonly Dictionary<EntityUid, int> EntityUidMap = new();
             private readonly Dictionary<int, EntityUid> UidEntityMap = new();
             public readonly List<EntityUid> Entities = new();
 
-            private readonly List<(EntityUid, YamlMappingNode)> _entitiesToDeserialize
+            private readonly List<(EntityUid, MappingDataNode)> _entitiesToDeserialize
                 = new();
 
             private bool IsBlueprintMode => GridIDMap.Count == 1;
 
-            private readonly YamlMappingNode RootNode;
-            private readonly MapId TargetMap;
+            private readonly MappingDataNode RootNode;
+            public readonly MapId TargetMap;
 
-            private Dictionary<string, YamlMappingNode>? CurrentReadingEntityComponents;
+            private Dictionary<string, MappingDataNode>? CurrentReadingEntityComponents;
 
             private string? CurrentWritingComponent;
             private EntityUid? CurrentWritingEntity;
 
+            public IReadOnlyDictionary<ushort, string>? TileMap => _tileMap;
             private Dictionary<ushort, string>? _tileMap;
 
             public Dictionary<(Type, Type), object> TypeReaders { get; }
@@ -258,14 +271,16 @@ namespace Robust.Server.Maps
             public bool MapIsPostInit { get; private set; }
 
             public MapContext(IMapManagerInternal maps, ITileDefinitionManager tileDefs,
-                IServerEntityManagerInternal entities, IPrototypeManager prototypeManager)
+                IServerEntityManagerInternal entities, IPrototypeManager prototypeManager,
+                ISerializationManager serializationManager)
             {
                 _mapManager = maps;
                 _tileDefinitionManager = tileDefs;
                 _serverEntityManager = entities;
                 _prototypeManager = prototypeManager;
+                _serializationManager = serializationManager;
 
-                RootNode = new YamlMappingNode();
+                RootNode = new MappingDataNode();
                 TypeWriters = new Dictionary<Type, object>()
                 {
                     {typeof(GridId), this},
@@ -281,12 +296,14 @@ namespace Robust.Server.Maps
             public MapContext(IMapManagerInternal maps, ITileDefinitionManager tileDefs,
                 IServerEntityManagerInternal entities,
                 IPrototypeManager prototypeManager,
-                YamlMappingNode node, MapId targetMapId, MapLoadOptions options)
+                ISerializationManager serializationManager,
+                MappingDataNode node, MapId targetMapId, MapLoadOptions options)
             {
                 _mapManager = maps;
                 _tileDefinitionManager = tileDefs;
                 _serverEntityManager = entities;
                 _loadOptions = options;
+                _serializationManager = serializationManager;
 
                 RootNode = node;
                 TargetMap = targetMapId;
@@ -339,12 +356,16 @@ namespace Robust.Server.Maps
                 // We have to fix the created grids up with the grid entities deserialized from the map.
                 FixMapEntities();
 
+                _xformQuery = _serverEntityManager.GetEntityQuery<TransformComponent>();
+
                 // We have to attach grids to the target map here.
                 // If we don't, initialization & startup can fail for some entities.
                 AttachMapEntities();
 
                 ApplyGridFixtures();
 
+                AdjustEntityTransforms();
+
                 // Run Initialize on all components.
                 FinishEntitiesInitialization();
 
@@ -355,13 +376,13 @@ namespace Robust.Server.Maps
             private void VerifyEntitiesExist()
             {
                 var fail = false;
-                var entities = RootNode.GetNode<YamlSequenceNode>("entities");
+                var entities = RootNode.Get<SequenceDataNode>("entities");
                 var reportedError = new HashSet<string>();
-                foreach (var entityDef in entities.Cast<YamlMappingNode>())
+                foreach (var entityDef in entities.Cast<MappingDataNode>())
                 {
-                    if (entityDef.TryGetNode("type", out var typeNode))
+                    if (entityDef.TryGet<ValueDataNode>("type", out var typeNode))
                     {
-                        var type = typeNode.AsString();
+                        var type = typeNode.Value;
                         if (!_prototypeManager.HasIndex<EntityPrototype>(type) && !reportedError.Contains(type))
                         {
                             Logger.Error("Missing prototype for map: {0}", type);
@@ -384,7 +405,7 @@ namespace Robust.Server.Maps
 
                 foreach (var (entity, data) in _entitiesToDeserialize)
                 {
-                    if (!data.TryGetNode("components", out YamlSequenceNode? componentList))
+                    if (!data.TryGet("components", out SequenceDataNode? componentList))
                     {
                         continue;
                     }
@@ -399,7 +420,7 @@ namespace Robust.Server.Maps
                         var castComp = (Component) component;
                         var compName = compFactory.GetComponentName(castComp.GetType());
 
-                        if (componentList.Any(p => p["type"].AsString() == compName))
+                        if (componentList.Cast<MappingDataNode>().Any(p => ((ValueDataNode)p["type"]).Value == compName))
                         {
                             if (prototype.Components.ContainsKey(compName))
                             {
@@ -487,7 +508,7 @@ namespace Robust.Server.Maps
                 // Now we need to actually bind the MapGrids to their components so that you can resolve GridId -> EntityUid
                 // After doing this, it should be 100% safe to use the MapManager API like normal.
 
-                var yamlGrids = RootNode.GetNode<YamlSequenceNode>("grids");
+                var yamlGrids = RootNode.Get<SequenceDataNode>("grids");
 
                 // get ents that the grids will bind to
                 var gridComps = new Dictionary<GridId, MapGridComponent>(_readGridIndices.Count);
@@ -511,28 +532,30 @@ namespace Robust.Server.Maps
                 {
                     // Here is where the implicit index pairing magic happens from the yaml.
                     var gridIndex = _readGridIndices[index];
-                    var yamlGrid = (YamlMappingNode)yamlGrids.Children[index];
+                    var yamlGrid = (MappingDataNode)yamlGrids[index];
 
                     // designed to throw if something is broken, every grid must map to an ent
                     var gridComp = gridComps[gridIndex];
 
                     DebugTools.Assert(gridComp.GridIndex == gridIndex);
 
-                    YamlMappingNode yamlGridInfo = (YamlMappingNode)yamlGrid["settings"];
-                    YamlSequenceNode yamlGridChunks = (YamlSequenceNode)yamlGrid["chunks"];
+                    MappingDataNode yamlGridInfo = (MappingDataNode)yamlGrid["settings"];
+                    SequenceDataNode yamlGridChunks = (SequenceDataNode)yamlGrid["chunks"];
 
                     var grid = AllocateMapGrid(gridComp, yamlGridInfo);
 
-                    foreach (var chunkNode in yamlGridChunks.Cast<YamlMappingNode>())
+                    foreach (var chunkNode in yamlGridChunks.Cast<MappingDataNode>())
                     {
-                        YamlGridSerializer.DeserializeChunk(_mapManager, grid, chunkNode, _tileMap!, _tileDefinitionManager);
+                        var (chunkOffsetX, chunkOffsetY) = _serializationManager.Read<Vector2i>(chunkNode["ind"]);
+                        var chunk = grid.GetChunk(chunkOffsetX, chunkOffsetY);
+                        _serializationManager.Read(chunkNode, this, value: chunk);
                     }
 
                     Grids.Add(grid); // Grids are kept in index order
                 }
             }
 
-            private static MapGrid AllocateMapGrid(MapGridComponent gridComp, YamlMappingNode yamlGridInfo)
+            private static MapGrid AllocateMapGrid(MapGridComponent gridComp, MappingDataNode yamlGridInfo)
             {
                 // sane defaults
                 ushort csz = 16;
@@ -540,8 +563,8 @@ namespace Robust.Server.Maps
 
                 foreach (var kvInfo in yamlGridInfo)
                 {
-                    var key = kvInfo.Key.ToString();
-                    var val = kvInfo.Value.ToString();
+                    var key = ((ValueDataNode)kvInfo.Key).Value;
+                    var val = ((ValueDataNode)kvInfo.Value).Value;
                     if (key == "chunksize")
                         csz = ushort.Parse(val);
                     else if (key == "tilesize")
@@ -561,7 +584,7 @@ namespace Robust.Server.Maps
 
                 foreach (var grid in Grids)
                 {
-                    var transform = _serverEntityManager.GetComponent<TransformComponent>(grid.GridEntityId);
+                    var transform = _xformQuery!.Value.GetComponent(grid.GridEntityId);
                     if (transform.Parent != null)
                         continue;
 
@@ -590,14 +613,14 @@ namespace Robust.Server.Maps
 
             private void ReadMetaSection()
             {
-                var meta = RootNode.GetNode<YamlMappingNode>("meta");
-                var ver = meta.GetNode("format").AsInt();
+                var meta = RootNode.Get<MappingDataNode>("meta");
+                var ver = meta.Get<ValueDataNode>("format").AsInt();
                 if (ver != MapFormatVersion)
                 {
                     throw new InvalidDataException("Cannot handle this map file version.");
                 }
 
-                if (meta.TryGetNode("postmapinit", out var mapInitNode))
+                if (meta.TryGet<ValueDataNode>("postmapinit", out var mapInitNode))
                 {
                     MapIsPostInit = mapInitNode.AsBool();
                 }
@@ -612,11 +635,11 @@ namespace Robust.Server.Maps
                 // Load tile mapping so that we can map the stored tile IDs into the ones actually used at runtime.
                 _tileMap = new Dictionary<ushort, string>();
 
-                var tileMap = RootNode.GetNode<YamlMappingNode>("tilemap");
-                foreach (var (key, value) in tileMap)
+                var tileMap = RootNode.Get<MappingDataNode>("tilemap");
+                foreach (var (key, value) in tileMap.Children)
                 {
-                    var tileId = (ushort) key.AsInt();
-                    var tileDefName = value.AsString();
+                    var tileId = (ushort) ((ValueDataNode)key).AsInt();
+                    var tileDefName = ((ValueDataNode)value).Value;
                     _tileMap.Add(tileId, tileDefName);
                 }
             }
@@ -625,9 +648,9 @@ namespace Robust.Server.Maps
             {
                 // sets up the mapping so the serializer can properly deserialize GridIds.
 
-                var yamlGrids = RootNode.GetNode<YamlSequenceNode>("grids");
+                var yamlGrids = RootNode.Get<SequenceDataNode>("grids");
 
-                for (var i = 0; i < yamlGrids.Children.Count; i++)
+                for (var i = 0; i < yamlGrids.Count; i++)
                 {
                     _readGridIndices.Add(_mapManager.GenerateGridId(null));
                 }
@@ -652,17 +675,17 @@ namespace Robust.Server.Maps
 
             private void AllocEntities()
             {
-                var entities = RootNode.GetNode<YamlSequenceNode>("entities");
-                foreach (var entityDef in entities.Cast<YamlMappingNode>())
+                var entities = RootNode.Get<SequenceDataNode>("entities");
+                foreach (var entityDef in entities.Cast<MappingDataNode>())
                 {
                     string? type = null;
-                    if (entityDef.TryGetNode("type", out var typeNode))
+                    if (entityDef.TryGet<ValueDataNode>("type", out var typeNode))
                     {
-                        type = typeNode.AsString();
+                        type = typeNode.Value;
                     }
 
                     var uid = Entities.Count;
-                    if (entityDef.TryGetNode("uid", out var uidNode))
+                    if (entityDef.TryGet<ValueDataNode>("uid", out var uidNode))
                     {
                         uid = uidNode.AsInt();
                     }
@@ -684,15 +707,14 @@ namespace Robust.Server.Maps
             {
                 foreach (var (entity, data) in _entitiesToDeserialize)
                 {
-                    CurrentReadingEntityComponents = new Dictionary<string, YamlMappingNode>();
-                    if (data.TryGetNode("components", out YamlSequenceNode? componentList))
+                    CurrentReadingEntityComponents = new Dictionary<string, MappingDataNode>();
+                    if (data.TryGet("components", out SequenceDataNode? componentList))
                     {
-                        foreach (var compData in componentList)
+                        foreach (var compData in componentList.Cast<MappingDataNode>())
                         {
-                            var copy = new YamlMappingNode(((YamlMappingNode)compData).AsEnumerable());
-                            copy.Children.Remove(new YamlScalarNode("type"));
-                            //TODO Paul: maybe replace mapping with datanode
-                            CurrentReadingEntityComponents[compData["type"].AsString()] = copy;
+                            var datanode = compData.Copy();
+                            datanode.Remove("type");
+                            CurrentReadingEntityComponents[((ValueDataNode)compData["type"]).Value] = datanode;
                         }
                     }
 
@@ -700,6 +722,25 @@ namespace Robust.Server.Maps
                 }
             }
 
+            private void AdjustEntityTransforms()
+            {
+                var map = _mapManager.GetMapEntityId(TargetMap);
+
+                if (_loadOptions is null || _loadOptions.TransformMatrix.EqualsApprox(Matrix3.Identity))
+                    return;
+
+                foreach (var entity in Entities)
+                {
+                    if (!_xformQuery!.Value.TryGetComponent(entity, out var transform) ||
+                        transform.ParentUid != map) continue;
+
+                    var off = _loadOptions.TransformMatrix.Transform(transform.Coordinates.Position);
+
+                    transform.Coordinates = transform.Coordinates.WithPosition(off);
+                    transform.WorldRotation += _loadOptions.Rotation;
+                }
+            }
+
             private void FinishEntitiesInitialization()
             {
                 foreach (var entity in Entities)
@@ -737,12 +778,12 @@ namespace Robust.Server.Maps
                 PopulateEntityList();
                 WriteEntitySection();
 
-                return RootNode;
+                return RootNode.ToYaml();
             }
 
             private void WriteMetaSection()
             {
-                var meta = new YamlMappingNode();
+                var meta = new MappingDataNode();
                 RootNode.Add("meta", meta);
                 meta.Add("format", MapFormatVersion.ToString(CultureInfo.InvariantCulture));
                 // TODO: Make these values configurable.
@@ -764,7 +805,7 @@ namespace Robust.Server.Maps
 
             private void WriteTileMapSection()
             {
-                var tileMap = new YamlMappingNode();
+                var tileMap = new MappingDataNode();
                 RootNode.Add("tilemap", tileMap);
                 foreach (var tileDefinition in _tileDefinitionManager)
                 {
@@ -774,12 +815,12 @@ namespace Robust.Server.Maps
 
             private void WriteGridSection()
             {
-                var grids = new YamlSequenceNode();
+                var grids = new SequenceDataNode();
                 RootNode.Add("grids", grids);
 
                 foreach (var grid in Grids)
                 {
-                    var entry = YamlGridSerializer.SerializeGrid(grid);
+                    var entry = _serializationManager.WriteValue(grid, context: this);
                     grids.Add(entry);
                 }
             }
@@ -843,34 +884,35 @@ namespace Robust.Server.Maps
                 var serializationManager = IoCManager.Resolve<ISerializationManager>();
                 var compFactory = IoCManager.Resolve<IComponentFactory>();
                 var metaQuery = _serverEntityManager.GetEntityQuery<MetaDataComponent>();
-                var entities = new YamlSequenceNode();
+                var entities = new SequenceDataNode();
                 RootNode.Add("entities", entities);
 
                 var prototypeCompCache = new Dictionary<string, Dictionary<string, MappingDataNode>>();
                 foreach (var (saveId, entityUid) in UidEntityMap.OrderBy(e=>e.Key))
                 {
                     CurrentWritingEntity = entityUid;
-                    var mapping = new YamlMappingNode
+                    var mapping = new MappingDataNode
                     {
                         {"uid", saveId.ToString(CultureInfo.InvariantCulture)}
                     };
 
                     var md = metaQuery.GetComponent(entityUid);
 
+                    Dictionary<string, MappingDataNode>? cache = null;
                     if (md.EntityPrototype is {} prototype)
                     {
                         mapping.Add("type", prototype.ID);
-                        if (!prototypeCompCache.ContainsKey(prototype.ID))
+                        if (!prototypeCompCache.TryGetValue(prototype.ID, out cache))
                         {
-                            prototypeCompCache[prototype.ID] = new Dictionary<string, MappingDataNode>();
+                            prototypeCompCache[prototype.ID] = cache =  new Dictionary<string, MappingDataNode>();
                             foreach (var (compType, comp) in prototype.Components)
                             {
-                                prototypeCompCache[prototype.ID].Add(compType, serializationManager.WriteValueAs<MappingDataNode>(comp.GetType(), comp));
+                                cache.Add(compType, serializationManager.WriteValueAs<MappingDataNode>(comp.GetType(), comp));
                             }
                         }
                     }
 
-                    var components = new YamlSequenceNode();
+                    var components = new SequenceDataNode();
 
                     // See engine#636 for why the Distinct() call.
                     foreach (var component in _serverEntityManager.GetComponents(entityUid))
@@ -883,8 +925,10 @@ namespace Robust.Server.Maps
                         CurrentWritingComponent = compName;
                         var compMapping = serializationManager.WriteValueAs<MappingDataNode>(compType, component, context: this);
 
-                        if (md.EntityPrototype != null && prototypeCompCache[md.EntityPrototype.ID].TryGetValue(compName, out var protMapping))
+                        if (cache != null && cache.TryGetValue(compName, out var protMapping))
                         {
+                            // This will NOT recursively call Except() on the values of the mapping. It will only remove
+                            // key-value pairs if both the keys and values are equal.
                             compMapping = compMapping.Except(protMapping);
                             if(compMapping == null) continue;
                         }
@@ -894,11 +938,11 @@ namespace Robust.Server.Maps
                         {
                             compMapping.Add("type", new ValueDataNode(compName));
                             // Something actually got written!
-                            components.Add(compMapping.ToYamlNode());
+                            components.Add(compMapping);
                         }
                     }
 
-                    if (components.Children.Count != 0)
+                    if (components.Count != 0)
                     {
                         mapping.Add("components", components);
                     }
@@ -908,8 +952,8 @@ namespace Robust.Server.Maps
             }
 
             // Create custom object serializers that will correctly allow data to be overriden by the map file.
-            IComponent IEntityLoadContext.GetComponentData(string componentName,
-                IComponent? protoData)
+            MappingDataNode IEntityLoadContext.GetComponentData(string componentName,
+                MappingDataNode? protoData)
             {
                 if (CurrentReadingEntityComponents == null)
                 {
@@ -919,20 +963,15 @@ namespace Robust.Server.Maps
                 var serializationManager = IoCManager.Resolve<ISerializationManager>();
                 var factory = IoCManager.Resolve<IComponentFactory>();
 
-                IComponent data = protoData != null
-                    ? serializationManager.CreateCopy(protoData, this)!
-                    : (IComponent) Activator.CreateInstance(factory.GetRegistration(componentName).Type)!;
-
                 if (CurrentReadingEntityComponents.TryGetValue(componentName, out var mapping))
                 {
-                    var mapData = (IDeserializedDefinition) serializationManager.Read(
-                        factory.GetRegistration(componentName).Type,
-                        mapping.ToDataNode(), this);
-                    var newData = serializationManager.PopulateDataDefinition(data, mapData);
-                    data = (IComponent) newData.RawValue!;
+                    if (protoData == null) return mapping.Copy();
+
+                    return serializationManager.PushCompositionWithGenericNode(
+                        factory.GetRegistration(componentName).Type, new[] { protoData }, mapping, this);
                 }
 
-                return data;
+                return protoData ?? new MappingDataNode();
             }
 
             public IEnumerable<string> GetExtraComponentTypes()
@@ -947,10 +986,10 @@ namespace Robust.Server.Maps
                     : base(message) { }
             }
 
-            public DeserializationResult Read(ISerializationManager serializationManager, ValueDataNode node,
+            public GridId Read(ISerializationManager serializationManager, ValueDataNode node,
                 IDependencyCollection dependencies,
                 bool skipHook,
-                ISerializationContext? context = null)
+                ISerializationContext? context = null, GridId _ = default)
             {
                 // This is the code that deserializes the Grids index into the GridId. This has to happen between Grid allocation
                 // and when grids are bound to their entities.
@@ -966,7 +1005,7 @@ namespace Robust.Server.Maps
                     throw new MapLoadException($"Error in map file: found local grid ID '{val}' which does not exist.");
                 }
 
-                return new DeserializedValue<GridId>(_readGridIndices[val]);
+                return _readGridIndices[val];
             }
 
             ValidationNode ITypeValidator<EntityUid, ValueDataNode>.Validate(ISerializationManager serializationManager,
@@ -1032,15 +1071,15 @@ namespace Robust.Server.Maps
                 }
             }
 
-            DeserializationResult ITypeReader<EntityUid, ValueDataNode>.Read(ISerializationManager serializationManager,
+            EntityUid ITypeReader<EntityUid, ValueDataNode>.Read(ISerializationManager serializationManager,
                 ValueDataNode node,
                 IDependencyCollection dependencies,
                 bool skipHook,
-                ISerializationContext? context)
+                ISerializationContext? context, EntityUid _)
             {
                 if (node.Value == "null")
                 {
-                    return new DeserializedValue<EntityUid>(EntityUid.Invalid);
+                    return EntityUid.Invalid;
                 }
 
                 var val = int.Parse(node.Value);
@@ -1048,11 +1087,11 @@ namespace Robust.Server.Maps
                 if (val >= Entities.Count || !UidEntityMap.ContainsKey(val) || !Entities.TryFirstOrNull(e => e == UidEntityMap[val], out var entity))
                 {
                     Logger.ErrorS("map", "Error in map file: found local entity UID '{0}' which does not exist.", val);
-                    return null!;
+                    return EntityUid.Invalid;
                 }
                 else
                 {
-                    return new DeserializedValue<EntityUid>(entity!.Value);
+                    return entity!.Value;
                 }
             }
 

Robust.Server/Maps/YamlGridSerializer.cs

@@ -1,120 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Globalization;
-using System.IO;
-using System.Linq;
-using Robust.Shared.Map;
-using Robust.Shared.Utility;
-using YamlDotNet.Core;
-using YamlDotNet.RepresentationModel;
-
-namespace Robust.Server.Maps
-{
-    internal static class YamlGridSerializer
-    {
-        public static YamlMappingNode SerializeGrid(IMapGrid mapGrid)
-        {
-            var grid = (IMapGridInternal) mapGrid;
-
-            var gridn = new YamlMappingNode();
-            var info = new YamlMappingNode();
-            var chunkSeq = new YamlSequenceNode();
-
-            gridn.Add("settings", info);
-            gridn.Add("chunks", chunkSeq);
-
-            info.Add("chunksize", grid.ChunkSize.ToString(CultureInfo.InvariantCulture));
-            info.Add("tilesize", grid.TileSize.ToString(CultureInfo.InvariantCulture));
-
-            var chunks = grid.GetMapChunks();
-            foreach (var chunk in chunks)
-            {
-                var chunkNode = SerializeChunk(chunk.Value);
-                chunkSeq.Add(chunkNode);
-            }
-
-            return gridn;
-        }
-
-        private static YamlNode SerializeChunk(MapChunk chunk)
-        {
-            var root = new YamlMappingNode();
-            var value = new YamlScalarNode($"{chunk.X},{chunk.Y}");
-            value.Style = ScalarStyle.DoubleQuoted;
-            root.Add("ind", value);
-
-            var gridNode = new YamlScalarNode();
-            root.Add("tiles", gridNode);
-
-            gridNode.Value = SerializeTiles(chunk);
-
-            return root;
-        }
-
-        private static string SerializeTiles(MapChunk chunk)
-        {
-            // number of bytes written per tile, because sizeof(Tile) is useless.
-            const int structSize = 4;
-
-            var nTiles = chunk.ChunkSize * chunk.ChunkSize * structSize;
-            var barr = new byte[nTiles];
-
-            using (var stream = new MemoryStream(barr))
-            using (var writer = new BinaryWriter(stream))
-            {
-                for (ushort y = 0; y < chunk.ChunkSize; y++)
-                {
-                    for (ushort x = 0; x < chunk.ChunkSize; x++)
-                    {
-                        var tile = chunk.GetTile(x, y);
-                        writer.Write(tile.TypeId);
-                        writer.Write((byte)tile.Flags);
-                        writer.Write(tile.Variant);
-                    }
-                }
-            }
-
-            return Convert.ToBase64String(barr);
-        }
-
-        public static void DeserializeChunk(IMapManager mapMan, IMapGridInternal grid,
-            YamlMappingNode chunkData,
-            IReadOnlyDictionary<ushort, string> tileDefMapping,
-            ITileDefinitionManager tileDefinitionManager)
-        {
-            var indNode = chunkData["ind"];
-            var tileNode = chunkData["tiles"];
-
-            var (chunkOffsetX, chunkOffsetY) = indNode.AsVector2i();
-            var tileBytes = Convert.FromBase64String(tileNode.ToString());
-
-            using var stream = new MemoryStream(tileBytes);
-            using var reader = new BinaryReader(stream);
-
-            mapMan.SuppressOnTileChanged = true;
-
-            var chunk = grid.GetChunk(chunkOffsetX, chunkOffsetY);
-
-            chunk.SuppressCollisionRegeneration = true;
-
-            for (ushort y = 0; y < grid.ChunkSize; y++)
-            {
-                for (ushort x = 0; x < grid.ChunkSize; x++)
-                {
-                    var id = reader.ReadUInt16();
-                    var flags = (TileRenderFlag)reader.ReadByte();
-                    var variant = reader.ReadByte();
-
-                    var defName = tileDefMapping[id];
-                    id = tileDefinitionManager[defName].TileId;
-
-                    var tile = new Tile(id, flags, variant);
-                    chunk.SetTile(x, y, tile);
-                }
-            }
-
-            chunk.SuppressCollisionRegeneration = false;
-            mapMan.SuppressOnTileChanged = false;
-        }
-    }
-}

Robust.Server/Placement/PlacementManager.cs

@@ -230,7 +230,7 @@ namespace Robust.Server.Placement
             if (playerConnection == null)
                 return;
 
-            var message = _networkManager.CreateNetMessage<MsgPlacement>();
+            var message = new MsgPlacement();
             message.PlaceType = PlacementManagerMessage.StartPlacement;
             message.Range = range;
             message.IsTile = false;
@@ -251,7 +251,7 @@ namespace Robust.Server.Placement
             if (playerConnection == null)
                 return;
 
-            var message = _networkManager.CreateNetMessage<MsgPlacement>();
+            var message = new MsgPlacement();
             message.PlaceType = PlacementManagerMessage.StartPlacement;
             message.Range = range;
             message.IsTile = true;
@@ -272,7 +272,7 @@ namespace Robust.Server.Placement
             if (playerConnection == null)
                 return;
 
-            var message = _networkManager.CreateNetMessage<MsgPlacement>();
+            var message = new MsgPlacement();
             message.PlaceType = PlacementManagerMessage.CancelPlacement;
             _networkManager.ServerSendMessage(message, playerConnection);
         }

Robust.Server/Player/PlayerManager.cs

@@ -445,7 +445,7 @@ namespace Robust.Server.Player
         {
             var channel = message.MsgChannel;
             var players = Sessions;
-            var netMsg = channel.CreateNetMessage<MsgPlayerList>();
+            var netMsg = new MsgPlayerList();
 
             // client session is complete, set their status accordingly.
             // This is done before the packet is built, so that the client

Robust.Server/Robust.Server.csproj

@@ -11,6 +11,7 @@
   <Import Project="..\MSBuild\Robust.DefineConstants.targets" />
   <ItemGroup>
     <PackageReference Include="JetBrains.Annotations" Version="2021.3.0" PrivateAssets="All" />
+    <PackageReference Include="SpaceWizards.HttpListener" Version="0.1.0" />
     <!--  -->
     <PackageReference Include="SQLitePCLRaw.bundle_e_sqlite3" Version="2.0.7" />
     <PackageReference Include="prometheus-net" Version="4.1.1" />
@@ -20,7 +21,6 @@
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Lidgren.Network\Lidgren.Network.csproj" />
-    <ProjectReference Include="..\ManagedHttpListener\src\System.Net.HttpListener.csproj" />
     <ProjectReference Include="..\Robust.Physics\Robust.Physics.csproj" />
     <ProjectReference Include="..\Robust.Shared.Maths\Robust.Shared.Maths.csproj" />
     <ProjectReference Include="..\Robust.Shared.Scripting\Robust.Shared.Scripting.csproj" />

Robust.Server/Scripting/ScriptHost.cs

@@ -75,7 +75,7 @@ namespace Robust.Server.Scripting
 
         private void ReceiveScriptStart(MsgScriptStart message)
         {
-            var reply = _netManager.CreateNetMessage<MsgScriptStartAck>();
+            var reply = new MsgScriptStartAck();
             reply.ScriptSession = message.ScriptSession;
             reply.WasAccepted = false;
             if (!_playerManager.TryGetSessionByChannel(message.MsgChannel, out var session))
@@ -128,7 +128,7 @@ namespace Robust.Server.Scripting
                 return;
             }
 
-            var replyMessage = _netManager.CreateNetMessage<MsgScriptResponse>();
+            var replyMessage = new MsgScriptResponse();
             replyMessage.ScriptSession = message.ScriptSession;
 
             var code = message.Code;
@@ -259,7 +259,7 @@ namespace Robust.Server.Scripting
                 !instances.TryGetValue(message.ScriptSession, out var instance))
                     return;
 
-            var replyMessage = _netManager.CreateNetMessage<MsgScriptCompletionResponse>();
+            var replyMessage = new MsgScriptCompletionResponse();
             replyMessage.ScriptSession = message.ScriptSession;
 
             // Everything below here cribbed from

Robust.Server/ServerStatus/IStatusHandlerContext.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Net;
 using System.Net.Http;
 using System.Threading.Tasks;
@@ -11,10 +12,18 @@ namespace Robust.Server.ServerStatus
     {
         HttpMethod RequestMethod { get; }
         IPEndPoint RemoteEndPoint { get; }
+
+        /// <summary>
+        /// Stream that reads the request body data,
+        /// </summary>
+        Stream RequestBody { get; }
         Uri Url { get; }
         bool IsGetLike { get; }
         IReadOnlyDictionary<string, StringValues> RequestHeaders { get; }
 
+        IDictionary<string, string> ResponseHeaders { get; }
+        bool KeepAlive { get; set; }
+
         [Obsolete("Use async versions instead")]
         T? RequestBodyJson<T>();
         Task<T?> RequestBodyJsonAsync<T>();
@@ -43,6 +52,8 @@ namespace Robust.Server.ServerStatus
             int code = 200,
             string contentType = "text/plain");
 
+        Task RespondNoContentAsync();
+
         Task RespondAsync(
             string text,
             HttpStatusCode code = HttpStatusCode.OK,
@@ -72,5 +83,7 @@ namespace Robust.Server.ServerStatus
         void RespondJson(object jsonData, HttpStatusCode code = HttpStatusCode.OK);
 
         Task RespondJsonAsync(object jsonData, HttpStatusCode code = HttpStatusCode.OK);
+
+        Task<Stream> RespondStreamAsync(HttpStatusCode code = HttpStatusCode.OK);
     }
 }

Robust.Server/ServerStatus/StatusHost.Acz.cs

@@ -0,0 +1,654 @@
+using System;
+using System.Buffers;
+using System.Buffers.Binary;
+using System.Collections;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Diagnostics;
+using System.IO;
+using System.IO.Compression;
+using System.Linq;
+using System.Net;
+using System.Net.Http;
+using System.Security.Cryptography;
+using Robust.Shared;
+using Robust.Shared.ContentPack;
+using Robust.Shared.Utility;
+using Robust.Shared.Utility.Collections;
+using SharpZstd.Interop;
+using SpaceWizards.Sodium;
+
+namespace Robust.Server.ServerStatus
+{
+    // Contains primary logic for ACZ (Automatic Client Zip)
+    // This entails the following:
+    // * Automatic generation of client zip on development servers.
+    // * Loading of pre-built client zip on release servers. ("Hybrid ACZ")
+    // * Distribution of the above two via status host, to facilitate easier server setup.
+    // * Manifest-based download system from the above.
+
+    internal sealed partial class StatusHost
+    {
+        // Lock used while working on the ACZ.
+        private readonly SemaphoreSlim _aczLock = new(1, 1);
+
+        // If an attempt has been made to prepare the ACZ.
+        private bool _aczPrepareAttempted = false;
+
+        // Automatic Client Zip
+        private AutomaticClientZipInfo? _aczPrepared;
+
+        private (string binFolder, string[] assemblies)? _aczInfo;
+
+        private void AddAczHandlers()
+        {
+            AddHandler(HandleAutomaticClientZip);
+            AddHandler(HandleAczManifest);
+            AddHandler(HandleAczManifestDownload);
+        }
+
+        private void InitAcz()
+        {
+            _cfg.OnValueChanged(CVars.AczStreamCompress, _ => InvalidateAcz());
+            _cfg.OnValueChanged(CVars.AczStreamCompressLevel, _ => InvalidateAcz());
+            _cfg.OnValueChanged(CVars.AczBlobCompress, _ => InvalidateAcz());
+            _cfg.OnValueChanged(CVars.AczBlobCompressLevel, _ => InvalidateAcz());
+            _cfg.OnValueChanged(CVars.AczBlobCompressSaveThreshold, _ => InvalidateAcz());
+            _cfg.OnValueChanged(CVars.AczManifestCompress, _ => InvalidateAcz());
+            _cfg.OnValueChanged(CVars.AczManifestCompressLevel, _ => InvalidateAcz());
+        }
+
+        private void InvalidateAcz()
+        {
+            using var _ = _aczLock.WaitGuard();
+
+            if (_aczPrepared == null)
+                return;
+
+            _aczSawmill.Info("ACZ CVars changed, invalidating ACZ data.");
+
+            _aczPrepared = null;
+            _aczPrepareAttempted = false;
+        }
+
+        private async Task<bool> HandleAutomaticClientZip(IStatusHandlerContext context)
+        {
+            if (!context.IsGetLike || context.Url!.AbsolutePath != "/client.zip")
+            {
+                return false;
+            }
+
+            if (!string.IsNullOrEmpty(_cfg.GetCVar(CVars.BuildDownloadUrl)))
+            {
+                await context.RespondAsync("This server has a build download URL.", HttpStatusCode.NotFound);
+                return true;
+            }
+
+            var result = await PrepareACZ();
+            if (result == null)
+            {
+                await context.RespondAsync("Automatic Client Zip was not preparable.",
+                    HttpStatusCode.InternalServerError);
+                return true;
+            }
+
+            await context.RespondAsync(result.ZipData, HttpStatusCode.OK, "application/zip");
+            return true;
+        }
+
+        private async Task<bool> HandleAczManifest(IStatusHandlerContext context)
+        {
+            if (!context.IsGetLike || context.Url!.AbsolutePath != "/manifest.txt")
+                return false;
+
+            if (!string.IsNullOrEmpty(_cfg.GetCVar(CVars.BuildManifestUrl)))
+            {
+                await context.RespondAsync("This server has a build manifest URL.", HttpStatusCode.NotFound);
+                return true;
+            }
+
+            var result = await PrepareACZ();
+            if (result == null)
+            {
+                await context.RespondAsync("Automatic Client Zip was not preparable.",
+                    HttpStatusCode.InternalServerError);
+                return true;
+            }
+
+            if (RequestWantsZStd(context) && result.ManifestCompressed)
+            {
+                context.ResponseHeaders.Add("Content-Encoding", "zstd");
+
+                await context.RespondAsync(result.ManifestData, HttpStatusCode.OK);
+            }
+            else
+            {
+                if (result.ManifestCompressed)
+                {
+                    // Manifest is compressed in-memory but client didn't want it compressed.
+                    // Have to decompress ourselves.
+
+                    var ms = new MemoryStream(result.ManifestData);
+
+                    await using var stream = await context.RespondStreamAsync();
+                    await using var decompressStream = new ZStdDecompressStream(ms);
+
+                    await decompressStream.CopyToAsync(stream);
+                }
+                else
+                {
+                    await context.RespondAsync(result.ManifestData, HttpStatusCode.OK);
+                }
+            }
+
+            return true;
+        }
+
+        private async Task<bool> HandleAczManifestDownload(IStatusHandlerContext context)
+        {
+            if (context.Url.AbsolutePath != "/download")
+                return false;
+
+            if (context.RequestHeaders.ContainsKey("Content-Type")
+                && context.RequestHeaders["Content-Type"] != "application/octet-stream")
+            {
+                await context.RespondAsync(
+                    "Must specify application/octet-stream Content-Type",
+                    HttpStatusCode.BadRequest);
+            }
+
+            if (!string.IsNullOrEmpty(_cfg.GetCVar(CVars.BuildManifestUrl)))
+            {
+                await context.RespondAsync("This server has a build manifest URL.", HttpStatusCode.NotFound);
+                return true;
+            }
+
+            // HTTP OPTIONS
+            if (context.RequestMethod == HttpMethod.Options)
+            {
+                context.ResponseHeaders["X-Robust-Download-Min-Protocol"] = "1";
+                context.ResponseHeaders["X-Robust-Download-Max-Protocol"] = "1";
+                await context.RespondNoContentAsync();
+                return true;
+            }
+
+            if (context.RequestMethod != HttpMethod.Post)
+                return false;
+
+            var aczInfo = await PrepareACZ();
+            if (aczInfo == null)
+            {
+                await context.RespondAsync("Automatic Client Zip was not preparable.",
+                    HttpStatusCode.InternalServerError);
+                return true;
+            }
+
+            // HTTP POST: main handling system.
+
+            // Verify version request header.
+            // Right now only one version ("1") exists, so...
+
+            // Request body not yet read, don't allow keepalive.
+            context.KeepAlive = false;
+            if (!context.RequestHeaders.TryGetValue("X-Robust-Download-Protocol", out var versionHeader)
+                || versionHeader.Count != 1
+                || !Parse.TryInt32(versionHeader[0], out var version))
+            {
+                await context.RespondAsync("Expected single X-Robust-Download-Protocol header",
+                    HttpStatusCode.BadRequest);
+                return true;
+            }
+
+            if (version != 1)
+            {
+                await context.RespondAsync("Unsupported download protocol version", HttpStatusCode.NotImplemented);
+                return true;
+            }
+
+            var fileCount = aczInfo.ManifestEntries.Length;
+
+            var requestBufSize = fileCount * 4;
+            var pool = ArrayPool<byte>.Shared.Rent(requestBufSize);
+            using var poolGuard = ArrayPool<byte>.Shared.ReturnGuard(pool);
+            var buffer = new MemoryStream(
+                pool,
+                0, requestBufSize,
+                writable: true,
+                publiclyVisible: true);
+
+            try
+            {
+                await context.RequestBody.CopyToAsync(buffer);
+            }
+            catch (NotSupportedException)
+            {
+                // Thrown by memory stream if full.
+                await context.RespondAsync("Request too large", HttpStatusCode.RequestEntityTooLarge);
+                return true;
+            }
+
+            // Request body read, allow keepalive again.
+            context.KeepAlive = true;
+
+            // Request body read. Validate it.
+            // Do not allow out-of-bounds files or duplicate requests.
+
+            var buf = pool.AsMemory(0, (int)buffer.Position);
+
+            var manifestLength = aczInfo.ManifestEntries.Length;
+            var bits = new BitArray(manifestLength);
+            var offset = 0;
+            while (offset < buf.Length)
+            {
+                var index = BinaryPrimitives.ReadInt32LittleEndian(buf.Slice(offset, 4).Span);
+
+                if (index < 0 || index >= manifestLength)
+                {
+                    await context.RespondAsync("Out of bounds manifest index", HttpStatusCode.BadRequest);
+                    return true;
+                }
+
+                if (bits[index])
+                {
+                    await context.RespondAsync("Cannot request file twice", HttpStatusCode.BadRequest);
+                    return true;
+                }
+
+                bits[index] = true;
+
+                offset += 4;
+            }
+
+            // There is a theoretical tiny race condition here where the main thread may change these parameters
+            // between us acquiring the ACZ info above and reading them here.
+            // The worst that could happen here is that the stream is either double-compressed or not compressed at all,
+            // So I am not too worried and am just gonna leave it as-is.
+
+            var cVarStreamCompression = _cfg.GetCVar(CVars.AczStreamCompress);
+            var cVarStreamCompressionLevel = _cfg.GetCVar(CVars.AczStreamCompressLevel);
+
+            // Only do zstd stream compression if the client asks for it and we have it enabled.
+            var doStreamCompression = RequestWantsZStd(context)
+                                      && cVarStreamCompression;
+
+            if (doStreamCompression)
+                context.ResponseHeaders["Content-Encoding"] = "zstd";
+
+            var outStream = await context.RespondStreamAsync();
+
+            if (doStreamCompression)
+            {
+                var zStdCompressStream = new ZStdCompressStream(outStream);
+                zStdCompressStream.Context.SetParameter(
+                    ZSTD_cParameter.ZSTD_c_compressionLevel,
+                    cVarStreamCompressionLevel);
+
+                outStream = zStdCompressStream;
+            }
+
+            var preCompressed = aczInfo.PreCompressed;
+
+            var fileHeaderSize = 4;
+            if (preCompressed)
+                fileHeaderSize += 4;
+
+            var fileHeader = new byte[fileHeaderSize];
+
+            await using (outStream)
+            {
+                var streamHeader = new byte[4];
+                DownloadStreamHeaderFlags streamHeaderFlags = 0;
+                if (preCompressed)
+                    streamHeaderFlags |= DownloadStreamHeaderFlags.PreCompressed;
+
+                BinaryPrimitives.WriteInt32LittleEndian(streamHeader, (int)streamHeaderFlags);
+
+                await outStream.WriteAsync(streamHeader);
+
+                offset = 0;
+                while (offset < buf.Length)
+                {
+                    var index = BinaryPrimitives.ReadInt32LittleEndian(buf.Slice(offset, 4).Span);
+
+                    var (blobLength, dataOffset, dataLength) = aczInfo.ManifestEntries[index];
+
+                    // _aczSawmill.Debug($"{index:D5}: {blobLength:D8} {dataOffset:D8} {dataLength:D8}");
+
+                    BinaryPrimitives.WriteInt32LittleEndian(fileHeader, blobLength);
+
+                    if (preCompressed)
+                        BinaryPrimitives.WriteInt32LittleEndian(fileHeader.AsSpan(4, 4), dataLength);
+
+                    var writeLength = dataLength == 0 ? blobLength : dataLength;
+
+                    await outStream.WriteAsync(fileHeader);
+
+                    await outStream.WriteAsync(aczInfo.ManifestBlobData.AsMemory(dataOffset, writeLength));
+
+                    offset += 4;
+                }
+            }
+
+            return true;
+        }
+
+        private static bool RequestWantsZStd(IStatusHandlerContext context)
+        {
+            // Yeah this isn't a good parser for Accept-Encoding but who cares.
+            return context.RequestHeaders.TryGetValue("Accept-Encoding", out var ac) && ac[0].Contains("zstd");
+        }
+
+        // Only call this if the download URL is not available!
+        private async Task<AutomaticClientZipInfo?> PrepareACZ()
+        {
+            // Take the ACZ lock asynchronously
+            await _aczLock.WaitAsync();
+            try
+            {
+                // Setting this now ensures that it won't fail repeatedly on exceptions/etc.
+                if (_aczPrepareAttempted)
+                    return _aczPrepared;
+
+                _aczPrepareAttempted = true;
+                // ACZ hasn't been prepared, prepare it
+                try
+                {
+                    // Run actual ACZ generation via Task.Run because it's synchronous
+                    var maybeData = await Task.Run(PrepareACZInnards);
+                    if (maybeData == null)
+                    {
+                        _aczSawmill.Error("StatusHost PrepareACZ failed (server will not be usable from launcher!)");
+                        return null;
+                    }
+
+                    _aczPrepared = maybeData;
+                    return maybeData;
+                }
+                catch (Exception e)
+                {
+                    _aczSawmill.Error(
+                        $"Exception in StatusHost PrepareACZ (server will not be usable from launcher!): {e}");
+                    return null;
+                }
+            }
+            finally
+            {
+                _aczLock.Release();
+            }
+        }
+
+        // -- All methods from this point forward do not access the ACZ global state --
+
+        private AutomaticClientZipInfo? PrepareACZInnards()
+        {
+            _aczSawmill.Info("Preparing ACZ...");
+            // All of these should Info on success and Error on null-return failure
+            var zipData = PrepareACZViaFile() ?? PrepareACZViaMagic();
+            if (zipData == null)
+                return null;
+
+            var streamCompression = _cfg.GetCVar(CVars.AczStreamCompress);
+            var blobCompress = _cfg.GetCVar(CVars.AczBlobCompress);
+            var blobCompressLevel = _cfg.GetCVar(CVars.AczBlobCompressLevel);
+            var blobCompressSaveThresh = _cfg.GetCVar(CVars.AczBlobCompressSaveThreshold);
+            var manifestCompress = _cfg.GetCVar(CVars.AczManifestCompress);
+            var manifestCompressLevel = _cfg.GetCVar(CVars.AczManifestCompressLevel);
+
+            // Stream compression disables individual compression.
+            blobCompress &= !streamCompression;
+
+            _aczSawmill.Debug("Making ACZ manifest...");
+            var dataHash = Convert.ToHexString(SHA256.HashData(zipData));
+
+            using var zip = OpenZip(zipData);
+            var (manifestData, manifestEntries, manifestBlobData) = CalcManifestData(
+                zip,
+                blobCompress,
+                blobCompressLevel,
+                blobCompressSaveThresh);
+
+            var manifestHash = CryptoGenericHashBlake2B.Hash(32, manifestData, ReadOnlySpan<byte>.Empty);
+            var manifestHashString = Convert.ToHexString(manifestHash);
+
+            _aczSawmill.Debug("ACZ Manifest hash: {ManifestHash}", manifestHashString);
+
+            if (manifestCompress)
+            {
+                _aczSawmill.Debug("Compressing ACZ manifest at level {ManifestCompressLevel}", manifestCompressLevel);
+
+                var beforeSize = manifestData.Length;
+                var compressBuffer = (int) Zstd.ZSTD_COMPRESSBOUND((nuint) manifestData.Length);
+                var compressed = ArrayPool<byte>.Shared.Rent(compressBuffer);
+
+                var size = ZStd.Compress(compressed, manifestData, manifestCompressLevel);
+
+                manifestData = compressed[..size];
+
+                ArrayPool<byte>.Shared.Return(compressed);
+
+                _aczSawmill.Debug(
+                    "ACZ manifest compression: {ManifestSize} -> {ManifestSizeCompressed} ({ManifestSizeRatio} ratio)",
+                    beforeSize, manifestData.Length, manifestData.Length / (float) beforeSize);
+            }
+
+            return new AutomaticClientZipInfo(
+                zipData,
+                dataHash,
+                manifestData,
+                manifestCompress,
+                manifestHashString,
+                manifestBlobData,
+                manifestEntries,
+                blobCompress);
+        }
+
+        private static (byte[] manifestContent, AczManifestEntry[] manifestEntries, byte[] blobData)
+            CalcManifestData(
+                ZipArchive zip,
+                bool blobCompress,
+                int blobCompressLevel,
+                int blobCompressSaveThresh)
+        {
+            var blobData = new MemoryStream();
+            ZStdCompressStream? compressStream = null;
+            if (blobCompress)
+            {
+                var zStdCompressStream = new ZStdCompressStream(blobData);
+                zStdCompressStream.Context.SetParameter(
+                    ZSTD_cParameter.ZSTD_c_compressionLevel,
+                    blobCompressLevel);
+
+                compressStream = zStdCompressStream;
+            }
+
+            try
+            {
+                var decompressBuffer = ArrayPool<byte>.Shared.Rent(1024 * 1024);
+                Span<byte> entryHash = stackalloc byte[256 / 8];
+
+                var manifestStream = new MemoryStream();
+                using var manifestWriter = new StreamWriter(manifestStream, EncodingHelpers.UTF8);
+                manifestWriter.Write("Robust Content Manifest 1\n");
+
+                var manifestEntries = new ValueList<AczManifestEntry>();
+
+                foreach (var entry in zip.Entries.OrderBy(e => e.FullName, StringComparer.Ordinal))
+                {
+                    // Ignore directory entries.
+                    if (entry.Name == "")
+                        continue;
+
+                    var length = (int)entry.Length;
+                    var startPos = (int)blobData.Position;
+
+                    BufferHelpers.EnsurePooledBuffer(ref decompressBuffer, ArrayPool<byte>.Shared, length);
+                    var data = decompressBuffer.AsSpan(0, length);
+
+                    using (var stream = entry.Open())
+                    {
+                        stream.ReadExact(data);
+                    }
+
+                    // Calculate hash.
+                    CryptoGenericHashBlake2B.Hash(entryHash, data, ReadOnlySpan<byte>.Empty);
+
+                    // Set to 0 to indicate not compressed.
+                    int dataLength;
+
+                    // Try compression if enabled.
+                    if (blobCompress)
+                    {
+                        // Actually compress.
+                        compressStream!.Write(data);
+                        compressStream.FlushEnd();
+
+                        // See if compression was worth it.
+                        var endPos = (int)blobData.Position;
+                        var compressedSize = endPos - startPos;
+                        if (compressedSize + blobCompressSaveThresh < length)
+                        {
+                            dataLength = compressedSize;
+                        }
+                        else
+                        {
+                            // Compression not worth it, just send an uncompressed blob instead.
+                            blobData.Position = startPos;
+                            blobData.Write(data);
+                            dataLength = 0;
+                        }
+                    }
+                    else
+                    {
+                        // No compression, just write.
+                        blobData.Write(data);
+                        dataLength = 0;
+                    }
+
+                    manifestWriter.Write($"{Convert.ToHexString(entryHash)} {entry.FullName}\n");
+
+                    manifestEntries.Add(new AczManifestEntry(length, startPos, dataLength));
+                }
+
+                manifestWriter.Flush();
+
+                ArrayPool<byte>.Shared.Return(decompressBuffer);
+
+                return (manifestStream.ToArray(), manifestEntries.ToArray(), blobData.ToArray());
+            }
+            finally
+            {
+                compressStream?.Dispose();
+            }
+        }
+
+        private static ZipArchive OpenZip(byte[] data)
+        {
+            var ms = new MemoryStream(data, false);
+            return new ZipArchive(ms, ZipArchiveMode.Read, leaveOpen: false);
+        }
+
+        private byte[]? PrepareACZViaFile()
+        {
+            var path = PathHelpers.ExecutableRelativeFile("Content.Client.zip");
+            if (!File.Exists(path)) return null;
+            _aczSawmill.Info($"StatusHost found client zip: {path}");
+            return File.ReadAllBytes(path);
+        }
+
+        private byte[]? PrepareACZViaMagic()
+        {
+            var sw = Stopwatch.StartNew();
+
+            var (binFolderPath, assemblyNames) =
+                _aczInfo ?? ("Content.Client", new[] { "Content.Client", "Content.Shared" });
+
+            var outStream = new MemoryStream();
+            var archive = new ZipArchive(outStream, ZipArchiveMode.Create);
+
+            foreach (var assemblyName in assemblyNames)
+            {
+                AttemptPullFromDisk($"Assemblies/{assemblyName}.dll", $"../../bin/{binFolderPath}/{assemblyName}.dll");
+                AttemptPullFromDisk($"Assemblies/{assemblyName}.pdb", $"../../bin/{binFolderPath}/{assemblyName}.pdb");
+            }
+
+            var prefix = PathHelpers.ExecutableRelativeFile("../../Resources");
+            foreach (var path in PathHelpers.GetFiles(prefix))
+            {
+                var relPath = Path.GetRelativePath(prefix, path);
+                if (OperatingSystem.IsWindows())
+                    relPath = relPath.Replace('\\', '/');
+                AttemptPullFromDisk(relPath, path);
+            }
+
+            archive.Dispose();
+            _aczSawmill.Info("StatusHost synthesized client zip in {Elapsed} ms!", sw.ElapsedMilliseconds);
+            return outStream.ToArray();
+
+            void AttemptPullFromDisk(string pathTo, string pathFrom)
+            {
+                // _aczSawmill.Debug($"StatusHost PrepareACZMagic: {pathFrom} -> {pathTo}");
+                var res = PathHelpers.ExecutableRelativeFile(pathFrom);
+                if (!File.Exists(res))
+                    return;
+
+                var entry = archive.CreateEntry(pathTo);
+
+                using var file = File.OpenRead(res);
+                using var entryStream = entry.Open();
+
+                file.CopyTo(entryStream);
+            }
+        }
+
+        public void SetAczInfo(string clientBinFolder, string[] clientAssemblyNames)
+        {
+            _aczLock.Wait();
+            try
+            {
+                if (_aczPrepared != null)
+                    throw new InvalidOperationException("ACZ already prepared");
+
+                _aczInfo = (clientBinFolder, clientAssemblyNames);
+            }
+            finally
+            {
+                _aczLock.Release();
+            }
+        }
+
+        [Flags]
+        private enum DownloadStreamHeaderFlags
+        {
+            None = 0,
+
+            /// <summary>
+            /// If this flag is set on the download stream, individual files have been pre-compressed by the server.
+            /// This means each file has a compression header, and the launcher should not attempt to compress files itself.
+            /// </summary>
+            PreCompressed = 1 << 0
+        }
+
+        /// <param name="ZipData">Byte array containing the raw zip file data.</param>
+        /// <param name="ZipHash">Hex SHA256 hash of <see cref="ZipData"/>.</param>
+        /// <param name="ManifestData">Data for the content manifest</param>
+        /// <param name="ManifestHash">Hex BLAKE2B 256-bit hash of <see cref="ManifestData"/>.</param>
+        /// <param name="ManifestEntries">Manifest -> zip entry map.</param>
+        internal sealed record AutomaticClientZipInfo(
+            byte[] ZipData,
+            string ZipHash,
+            byte[] ManifestData,
+            bool ManifestCompressed,
+            string ManifestHash,
+            byte[] ManifestBlobData,
+            AczManifestEntry[] ManifestEntries,
+            bool PreCompressed);
+
+        /// <param name="BlobLength">Length of the uncompressed blob.</param>
+        /// <param name="DataOffset">Offset into <see cref="AutomaticClientZipInfo.ManifestBlobData"/> that this blob's (possibly compressed) data starts at.</param>
+        /// <param name="DataLength">
+        /// Length in <see cref="AutomaticClientZipInfo.ManifestBlobData"/> for this blob's (possibly compressed) data.
+        /// If this is zero, it means the file is not stored uncompressed and you should use <see cref="BlobLength"/>.
+        /// </param>
+        internal record struct AczManifestEntry(int BlobLength, int DataOffset, int DataLength);
+    }
+}

Robust.Server/ServerStatus/StatusHost.ClientZip.cs

@@ -1,177 +0,0 @@
-using System;
-using System.Threading;
-using System.Threading.Tasks;
-using System.Collections.Generic;
-using System.IO;
-using System.IO.Compression;
-using System.Net;
-using System.Security.Cryptography;
-using Robust.Shared;
-using Robust.Shared.ContentPack;
-
-namespace Robust.Server.ServerStatus
-{
-
-    internal sealed partial class StatusHost
-    {
-        // Lock used while working on the ACZ.
-        private readonly SemaphoreSlim _aczLock = new(1, 1);
-        // If an attempt has been made to prepare the ACZ.
-        private bool _aczPrepareAttempted = false;
-        // Automatic Client Zip
-        private AutomaticClientZipInfo? _aczPrepared;
-
-        private (string binFolder, string[] assemblies)? _aczInfo;
-
-        private async Task<bool> HandleAutomaticClientZip(IStatusHandlerContext context)
-        {
-            if (!context.IsGetLike || context.Url!.AbsolutePath != "/client.zip")
-            {
-                return false;
-            }
-
-            if (!string.IsNullOrEmpty(_configurationManager.GetCVar(CVars.BuildDownloadUrl)))
-            {
-                await context.RespondAsync("This server has a build download URL.", HttpStatusCode.NotFound);
-                return true;
-            }
-
-            var result = await PrepareACZ();
-            if (result == null)
-            {
-                await context.RespondAsync("Automatic Client Zip was not preparable.", HttpStatusCode.InternalServerError);
-                return true;
-            }
-
-            await context.RespondAsync(result.Value.Data, HttpStatusCode.OK, "application/zip");
-            return true;
-        }
-
-        // Only call this if the download URL is not available!
-        private async Task<AutomaticClientZipInfo?> PrepareACZ()
-        {
-            // Take the ACZ lock asynchronously
-            await _aczLock.WaitAsync();
-            try
-            {
-                // Setting this now ensures that it won't fail repeatedly on exceptions/etc.
-                if (_aczPrepareAttempted) return _aczPrepared;
-                _aczPrepareAttempted = true;
-                // ACZ hasn't been prepared, prepare it
-                byte[] data;
-                try
-                {
-                    // Run actual ACZ generation via Task.Run because it's synchronous
-                    var maybeData = await Task.Run(PrepareACZInnards);
-                    if (maybeData == null)
-                    {
-                        _httpSawmill.Error("StatusHost PrepareACZ failed (server will not be usable from launcher!)");
-                        return null;
-                    }
-                    data = maybeData;
-                }
-                catch (Exception e)
-                {
-                    _httpSawmill.Error($"Exception in StatusHost PrepareACZ (server will not be usable from launcher!): {e}");
-                    return null;
-                }
-                _aczPrepared = new AutomaticClientZipInfo(data);
-                return _aczPrepared;
-            }
-            finally
-            {
-                _aczLock.Release();
-            }
-        }
-
-        // -- All methods from this point forward do not access the ACZ global state --
-
-        private byte[]? PrepareACZInnards()
-        {
-            // All of these should Info on success and Error on null-return failure
-            return PrepareACZViaFile() ?? PrepareACZViaMagic();
-        }
-
-        private byte[]? PrepareACZViaFile()
-        {
-            var path = PathHelpers.ExecutableRelativeFile("Content.Client.zip");
-            if (!File.Exists(path)) return null;
-            _httpSawmill.Info($"StatusHost found client zip: {path}");
-            return File.ReadAllBytes(path);
-        }
-
-        private byte[]? PrepareACZViaMagic()
-        {
-            var paths = new Dictionary<string, byte[]>();
-            bool AttemptPullFromDisk(string pathTo, string pathFrom)
-            {
-                // _httpSawmill.Debug($"StatusHost PrepareACZMagic: {pathFrom} -> {pathTo}");
-                var res = PathHelpers.ExecutableRelativeFile(pathFrom);
-                if (!File.Exists(res)) return false;
-                paths[pathTo] = File.ReadAllBytes(res);
-                return true;
-            }
-
-            var (binFolderPath, assemblyNames) =
-                _aczInfo ?? ("Content.Client", new[] { "Content.Client", "Content.Shared" });
-
-            foreach (var assemblyName in assemblyNames)
-            {
-                AttemptPullFromDisk($"Assemblies/{assemblyName}.dll", $"../../bin/{binFolderPath}/{assemblyName}.dll");
-                AttemptPullFromDisk($"Assemblies/{assemblyName}.pdb", $"../../bin/{binFolderPath}/{assemblyName}.pdb");
-            }
-
-            var prefix = PathHelpers.ExecutableRelativeFile("../../Resources");
-            foreach (var path in PathHelpers.GetFiles(prefix))
-            {
-                var relPath = Path.GetRelativePath(prefix, path);
-                if (OperatingSystem.IsWindows())
-                    relPath = relPath.Replace('\\', '/');
-                AttemptPullFromDisk(relPath, path);
-            }
-
-            var outStream = new MemoryStream();
-            var archive = new ZipArchive(outStream, ZipArchiveMode.Create);
-            foreach (var kvp in paths)
-            {
-                var entry = archive.CreateEntry(kvp.Key);
-                using (var entryStream = entry.Open())
-                {
-                    entryStream.Write(kvp.Value);
-                }
-            }
-            archive.Dispose();
-            _httpSawmill.Info($"StatusHost synthesized client zip!");
-            return outStream.ToArray();
-        }
-
-        public void SetAczInfo(string clientBinFolder, string[] clientAssemblyNames)
-        {
-            _aczLock.Wait();
-            try
-            {
-                if (_aczPrepared != null)
-                    throw new InvalidOperationException("ACZ already prepared");
-
-                _aczInfo = (clientBinFolder, clientAssemblyNames);
-            }
-            finally
-            {
-                _aczLock.Release();
-            }
-        }
-    }
-
-    internal struct AutomaticClientZipInfo
-    {
-        public readonly byte[] Data;
-        public readonly string Hash;
-
-        public AutomaticClientZipInfo(byte[] data)
-        {
-            Data = data;
-            using var sha = SHA256.Create();
-            Hash = Convert.ToHexString(sha.ComputeHash(data));
-        }
-    }
-}

Robust.Server/ServerStatus/StatusHost.Handlers.cs

@@ -15,7 +15,7 @@ namespace Robust.Server.ServerStatus
             AddHandler(HandleTeapot);
             AddHandler(HandleStatus);
             AddHandler(HandleInfo);
-            AddHandler(HandleAutomaticClientZip);
+            AddAczHandlers();
         }
 
         private static async Task<bool> HandleTeapot(IStatusHandlerContext context)
@@ -58,7 +58,7 @@ namespace Robust.Server.ServerStatus
                 return false;
             }
 
-            var downloadUrl = _configurationManager.GetCVar(CVars.BuildDownloadUrl);
+            var downloadUrl = _cfg.GetCVar(CVars.BuildDownloadUrl);
 
             JsonObject? buildInfo;
 
@@ -68,20 +68,7 @@ namespace Robust.Server.ServerStatus
             }
             else
             {
-                var hash = _configurationManager.GetCVar(CVars.BuildHash);
-                if (hash == "")
-                {
-                    hash = null;
-                }
-
-                buildInfo = new JsonObject
-                {
-                    ["engine_version"] = _configurationManager.GetCVar(CVars.BuildEngineVersion),
-                    ["fork_id"] = _configurationManager.GetCVar(CVars.BuildForkId),
-                    ["version"] = _configurationManager.GetCVar(CVars.BuildVersion),
-                    ["download_url"] = downloadUrl,
-                    ["hash"] = hash,
-                };
+                buildInfo = GetExternalBuildInfo();
             }
 
             var authInfo = new JsonObject
@@ -94,7 +81,7 @@ namespace Robust.Server.ServerStatus
 
             var jObject = new JsonObject
             {
-                ["connect_address"] = _configurationManager.GetCVar(CVars.StatusConnectAddress),
+                ["connect_address"] = _cfg.GetCVar(CVars.StatusConnectAddress),
                 ["auth"] = authInfo,
                 ["build"] = buildInfo
             };
@@ -106,6 +93,54 @@ namespace Robust.Server.ServerStatus
             return true;
         }
 
+        private JsonObject GetExternalBuildInfo()
+        {
+            var zipHash = _cfg.GetCVar(CVars.BuildHash);
+            var manifestHash = _cfg.GetCVar(CVars.BuildManifestHash);
+            var forkId = _cfg.GetCVar(CVars.BuildForkId);
+            var forkVersion = _cfg.GetCVar(CVars.BuildVersion);
+
+            var manifestDownloadUrl = Interpolate(_cfg.GetCVar(CVars.BuildManifestDownloadUrl));
+            var manifestUrl = Interpolate(_cfg.GetCVar(CVars.BuildManifestUrl));
+            var downloadUrl = Interpolate(_cfg.GetCVar(CVars.BuildDownloadUrl));
+
+            if (zipHash == "")
+                zipHash = null;
+
+            if (manifestHash == "")
+                manifestHash = null;
+
+            if (manifestDownloadUrl == "")
+                manifestDownloadUrl = null;
+
+            if (manifestUrl == "")
+                manifestUrl = null;
+
+            return new JsonObject
+            {
+                ["engine_version"] = _cfg.GetCVar(CVars.BuildEngineVersion),
+                ["fork_id"] = forkId,
+                ["version"] = forkVersion,
+                ["download_url"] = downloadUrl,
+                ["hash"] = zipHash,
+                ["acz"] = false,
+                ["manifest_download_url"] = manifestDownloadUrl,
+                ["manifest_url"] = manifestUrl,
+                ["manifest_hash"] = manifestHash
+            };
+
+            string? Interpolate(string? value)
+            {
+                // Can't tell if splitting the ?. like this is more cursed than
+                // failing to align due to putting the full ?. on the next line
+                return value?
+                    .Replace("{FORK_VERSION}", forkVersion)
+                    .Replace("{FORK_ID}", forkId)
+                    .Replace("{MANIFEST_HASH}", manifestHash)
+                    .Replace("{ZIP_HASH}", zipHash);
+            }
+        }
+
         private async Task<JsonObject?> PrepareACZBuildInfo()
         {
             var acz = await PrepareACZ();
@@ -113,10 +148,10 @@ namespace Robust.Server.ServerStatus
 
             // Automatic - pass to ACZ
             // Unfortunately, we still can't divine engine version.
-            var engineVersion = _configurationManager.GetCVar(CVars.BuildEngineVersion);
+            var engineVersion = _cfg.GetCVar(CVars.BuildEngineVersion);
             // Fork ID is an interesting case, we don't want to cause too many redownloads but we also don't want to pollute disk.
             // Call the fork "custom" if there's no explicit ID given.
-            var fork = _configurationManager.GetCVar(CVars.BuildForkId);
+            var fork = _cfg.GetCVar(CVars.BuildForkId);
             if (string.IsNullOrEmpty(fork))
             {
                 fork = "custom";
@@ -125,10 +160,15 @@ namespace Robust.Server.ServerStatus
             {
                 ["engine_version"] = engineVersion,
                 ["fork_id"] = fork,
-                ["version"] = acz.Value.Hash,
+                ["version"] = acz.ManifestHash,
                 // Don't supply a download URL - like supplying an empty self-address
                 ["download_url"] = "",
-                ["hash"] = acz.Value.Hash,
+                ["manifest_download_url"] = "",
+                ["manifest_url"] = "",
+                // Pass acz so the launcher knows where to find the downloads.
+                ["acz"] = true,
+                ["hash"] = acz.ZipHash,
+                ["manifest_hash"] = acz.ManifestHash
             };
         }
     }

Robust.Server/ServerStatus/StatusHost.cs

@@ -18,8 +18,8 @@ using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Network;
 using Robust.Shared.Utility;
-using HttpListener = ManagedHttpListener.HttpListener;
-using HttpListenerContext = ManagedHttpListener.HttpListenerContext;
+using HttpListener = SpaceWizards.HttpListener.HttpListener;
+using HttpListenerContext = SpaceWizards.HttpListener.HttpListenerContext;
 
 // This entire file is NIHing a REST server because pulling in libraries is effort.
 // Also it was fun to write.
@@ -31,7 +31,7 @@ namespace Robust.Server.ServerStatus
     {
         private const string Sawmill = "statushost";
 
-        [Dependency] private readonly IConfigurationManager _configurationManager = default!;
+        [Dependency] private readonly IConfigurationManager _cfg = default!;
         [Dependency] private readonly IServerNetManager _netManager = default!;
         [Dependency] private readonly IPlayerManager _playerManager = default!;
 
@@ -39,6 +39,7 @@ namespace Robust.Server.ServerStatus
         private HttpListener? _listener;
         private TaskCompletionSource? _stopSource;
         private ISawmill _httpSawmill = default!;
+        private ISawmill _aczSawmill = default!;
 
         private string? _serverNameCache;
 
@@ -95,13 +96,14 @@ namespace Robust.Server.ServerStatus
         public void Start()
         {
             _httpSawmill = Logger.GetSawmill($"{Sawmill}.http");
+            _aczSawmill = Logger.GetSawmill($"{Sawmill}.acz");
             RegisterCVars();
 
             // Cache this in a field to avoid thread safety shenanigans.
             // Writes/reads of references are atomic in C# so no further synchronization necessary.
-            _configurationManager.OnValueChanged(CVars.GameHostName, n => _serverNameCache = n, true);
+            _cfg.OnValueChanged(CVars.GameHostName, n => _serverNameCache = n, true);
 
-            if (!_configurationManager.GetCVar(CVars.StatusEnabled))
+            if (!_cfg.GetCVar(CVars.StatusEnabled))
             {
                 return;
             }
@@ -110,7 +112,7 @@ namespace Robust.Server.ServerStatus
 
             _stopSource = new TaskCompletionSource();
             _listener = new HttpListener();
-            _listener.Prefixes.Add($"http://{_configurationManager.GetCVar(CVars.StatusBind)}/");
+            _listener.Prefixes.Add($"http://{_cfg.GetCVar(CVars.StatusBind)}/");
             _listener.Start();
 
             Task.Run(ListenerThread);
@@ -119,7 +121,7 @@ namespace Robust.Server.ServerStatus
         // Not a real thread but whatever.
         private async Task ListenerThread()
         {
-            var maxConnections = _configurationManager.GetCVar(CVars.StatusMaxConnections);
+            var maxConnections = _cfg.GetCVar(CVars.StatusMaxConnections);
             var connectionsSemaphore = new SemaphoreSlim(maxConnections, maxConnections);
             while (true)
             {
@@ -157,6 +159,8 @@ namespace Robust.Server.ServerStatus
 
         private void RegisterCVars()
         {
+            InitAcz();
+
             // Set status host binding to match network manager by default
             SetCVarIfUnmodified(CVars.StatusBind, $"*:{_netManager.Port}");
 
@@ -173,19 +177,22 @@ namespace Robust.Server.ServerStatus
                 SetCVarIfUnmodified(CVars.BuildVersion, info.Version);
                 SetCVarIfUnmodified(CVars.BuildDownloadUrl, info.Download ?? "");
                 SetCVarIfUnmodified(CVars.BuildHash, info.Hash ?? "");
+                SetCVarIfUnmodified(CVars.BuildManifestHash, info.ManifestHash ?? "");
+                SetCVarIfUnmodified(CVars.BuildManifestDownloadUrl, info.ManifestDownloadUrl ?? "");
+                SetCVarIfUnmodified(CVars.BuildManifestUrl, info.ManifestUrl ?? "");
             }
 
             // Automatically determine engine version if no other source has provided a result
             var asmVer = typeof(StatusHost).Assembly.GetName().Version;
             if (asmVer != null)
             {
-                SetCVarIfUnmodified(CVars.BuildEngineVersion, asmVer.ToString(3));
+                SetCVarIfUnmodified(CVars.BuildEngineVersion, asmVer.ToString(4));
             }
 
             void SetCVarIfUnmodified(CVarDef<string> cvar, string val)
             {
-                if (_configurationManager.GetCVar(cvar) == "")
-                    _configurationManager.SetCVar(cvar, val);
+                if (_cfg.GetCVar(cvar) == "")
+                    _cfg.SetCVar(cvar, val);
             }
 
         }
@@ -211,17 +218,33 @@ namespace Robust.Server.ServerStatus
             [property: JsonPropertyName("fork_id")]
             string ForkId,
             [property: JsonPropertyName("version")]
-            string Version);
+            string Version,
+            [property: JsonPropertyName("manifest_hash")]
+            string? ManifestHash,
+            [property: JsonPropertyName("manifest_url")]
+            string? ManifestUrl,
+            [property: JsonPropertyName("manifest_download_url")]
+            string? ManifestDownloadUrl);
 
         private sealed class ContextImpl : IStatusHandlerContext
         {
             private readonly HttpListenerContext _context;
+            private readonly Dictionary<string, string> _responseHeaders;
             public HttpMethod RequestMethod { get; }
             public IPEndPoint RemoteEndPoint => _context.Request.RemoteEndPoint!;
+            public Stream RequestBody => _context.Request.InputStream;
             public Uri Url => _context.Request.Url!;
             public bool IsGetLike => RequestMethod == HttpMethod.Head || RequestMethod == HttpMethod.Get;
             public IReadOnlyDictionary<string, StringValues> RequestHeaders { get; }
 
+            public bool KeepAlive
+            {
+                get => _context.Response.KeepAlive;
+                set => _context.Response.KeepAlive = value;
+            }
+
+            public IDictionary<string, string> ResponseHeaders => _responseHeaders;
+
             public ContextImpl(HttpListenerContext context)
             {
                 _context = context;
@@ -237,16 +260,17 @@ namespace Robust.Server.ServerStatus
                 }
 
                 RequestHeaders = headers;
+                _responseHeaders = new Dictionary<string, string>();
             }
 
             public T? RequestBodyJson<T>()
             {
-                return JsonSerializer.Deserialize<T>(_context.Request.InputStream);
+                return JsonSerializer.Deserialize<T>(RequestBody);
             }
 
             public async Task<T?> RequestBodyJsonAsync<T>()
             {
-                return await JsonSerializer.DeserializeAsync<T>(_context.Request.InputStream);
+                return await JsonSerializer.DeserializeAsync<T>(RequestBody);
             }
 
             public void Respond(string text, HttpStatusCode code = HttpStatusCode.OK, string contentType = MediaTypeNames.Text.Plain)
@@ -290,6 +314,16 @@ namespace Robust.Server.ServerStatus
                 _context.Response.Close();
             }
 
+            public Task RespondNoContentAsync()
+            {
+                RespondShared();
+
+                _context.Response.StatusCode = (int) HttpStatusCode.NoContent;
+                _context.Response.Close();
+
+                return Task.CompletedTask;
+            }
+
             public Task RespondAsync(string text, HttpStatusCode code = HttpStatusCode.OK, string contentType = "text/plain")
             {
                 return RespondAsync(text, (int) code, contentType);
@@ -297,6 +331,8 @@ namespace Robust.Server.ServerStatus
 
             public async Task RespondAsync(string text, int code = 200, string contentType = "text/plain")
             {
+                RespondShared();
+
                 _context.Response.StatusCode = code;
                 _context.Response.ContentType = contentType;
 
@@ -315,6 +351,8 @@ namespace Robust.Server.ServerStatus
 
             public async Task RespondAsync(byte[] data, int code = 200, string contentType = "text/plain")
             {
+                RespondShared();
+
                 _context.Response.StatusCode = code;
                 _context.Response.ContentType = contentType;
                 _context.Response.ContentLength64 = data.Length;
@@ -341,6 +379,8 @@ namespace Robust.Server.ServerStatus
 
             public void RespondJson(object jsonData, HttpStatusCode code = HttpStatusCode.OK)
             {
+                RespondShared();
+
                 _context.Response.ContentType = "application/json";
 
                 JsonSerializer.Serialize(_context.Response.OutputStream, jsonData);
@@ -350,12 +390,31 @@ namespace Robust.Server.ServerStatus
 
             public async Task RespondJsonAsync(object jsonData, HttpStatusCode code = HttpStatusCode.OK)
             {
+                RespondShared();
+
                 _context.Response.ContentType = "application/json";
 
                 await JsonSerializer.SerializeAsync(_context.Response.OutputStream, jsonData);
 
                 _context.Response.Close();
             }
+
+            public Task<Stream> RespondStreamAsync(HttpStatusCode code = HttpStatusCode.OK)
+            {
+                RespondShared();
+
+                _context.Response.StatusCode = (int) code;
+
+                return Task.FromResult(_context.Response.OutputStream);
+            }
+
+            private void RespondShared()
+            {
+                foreach (var (header, value) in _responseHeaders)
+                {
+                    _context.Response.AddHeader(header, value);
+                }
+            }
         }
     }
 }

Robust.Server/ViewVariables/Traits/ViewVariablesTraitEntity.cs

@@ -38,7 +38,7 @@ namespace Robust.Server.ViewVariables.Traits
                 {
                     var type = component.GetType();
                     list.Add(new ViewVariablesBlobEntityComponents.Entry
-                        {Stringified = TypeAbbreviation.Abbreviate(type), FullName = type.FullName, ComponentName = component.Name});
+                        {Stringified = PrettyPrint.PrintUserFacingTypeShort(type, 2), FullName = type.FullName, ComponentName = component.Name});
                 }
 
                 return new ViewVariablesBlobEntityComponents

Robust.Server/ViewVariables/Traits/ViewVariablesTraitMembers.cs

@@ -44,7 +44,7 @@ namespace Robust.Server.ViewVariables.Traits
                         Editable = access == VVAccess.ReadWrite,
                         Name = property.Name,
                         Type = property.PropertyType.AssemblyQualifiedName,
-                        TypePretty = TypeAbbreviation.Abbreviate(property.PropertyType),
+                        TypePretty = PrettyPrint.PrintUserFacingTypeShort(property.PropertyType, 2),
                         Value = property.GetValue(Session.Object),
                         PropertyIndex = _members.Count
                     }, property));
@@ -63,7 +63,7 @@ namespace Robust.Server.ViewVariables.Traits
                         Editable = access == VVAccess.ReadWrite,
                         Name = field.Name,
                         Type = field.FieldType.AssemblyQualifiedName,
-                        TypePretty = TypeAbbreviation.Abbreviate(field.FieldType),
+                        TypePretty = PrettyPrint.PrintUserFacingTypeShort(field.FieldType, 2),
                         Value = field.GetValue(Session.Object),
                         PropertyIndex = _members.Count
                     }, field));

Robust.Server/ViewVariables/ViewVariablesHost.cs

@@ -26,7 +26,7 @@ namespace Robust.Server.ViewVariables
         [Dependency] private readonly IRobustSerializer _robustSerializer = default!;
         [Dependency] private readonly IReflectionManager _reflectionManager = default!;
 
-        private readonly Dictionary<uint, ViewVariablesesSession>
+        private readonly Dictionary<uint, ViewVariablesSession>
             _sessions = new();
 
         private uint _nextSessionId = 1;
@@ -91,7 +91,7 @@ namespace Robust.Server.ViewVariables
 
             var blob = session.DataRequest(message.RequestMeta);
 
-            var dataMsg = _netManager.CreateNetMessage<MsgViewVariablesRemoteData>();
+            var dataMsg = new MsgViewVariablesRemoteData();
             dataMsg.RequestId = message.RequestId;
             dataMsg.Blob = blob;
             _netManager.ServerSendMessage(dataMsg, message.MsgChannel);
@@ -101,7 +101,7 @@ namespace Robust.Server.ViewVariables
         {
             void Deny(DenyReason reason)
             {
-                var denyMsg = _netManager.CreateNetMessage<MsgViewVariablesDenySession>();
+                var denyMsg = new MsgViewVariablesDenySession();
                 denyMsg.RequestId = message.RequestId;
                 denyMsg.Reason = reason;
                 _netManager.ServerSendMessage(denyMsg, message.MsgChannel);
@@ -212,12 +212,12 @@ namespace Robust.Server.ViewVariables
             }
 
             var sessionId = _nextSessionId++;
-            var session = new ViewVariablesesSession(message.MsgChannel.UserId, theObject, sessionId, this,
+            var session = new ViewVariablesSession(message.MsgChannel.UserId, theObject, sessionId, this,
                 _robustSerializer);
 
             _sessions.Add(sessionId, session);
 
-            var allowMsg = _netManager.CreateNetMessage<MsgViewVariablesOpenSession>();
+            var allowMsg = new MsgViewVariablesOpenSession();
             allowMsg.RequestId = message.RequestId;
             allowMsg.SessionId = session.SessionId;
             _netManager.ServerSendMessage(allowMsg, message.MsgChannel);
@@ -245,7 +245,7 @@ namespace Robust.Server.ViewVariables
                 return;
             }
 
-            var closeMsg = _netManager.CreateNetMessage<MsgViewVariablesCloseSession>();
+            var closeMsg = new MsgViewVariablesCloseSession();
             closeMsg.SessionId = session.SessionId;
             _netManager.ServerSendMessage(closeMsg, player.ConnectedClient);
         }

Robust.Server/ViewVariables/ViewVariablesSession.cs

@@ -8,7 +8,7 @@ using Robust.Shared.ViewVariables;
 
 namespace Robust.Server.ViewVariables
 {
-    internal sealed class ViewVariablesesSession : IViewVariablesSession
+    internal sealed class ViewVariablesSession : IViewVariablesSession
     {
         private readonly List<ViewVariablesTrait> _traits = new();
         public IViewVariablesHost Host { get; }
@@ -24,7 +24,7 @@ namespace Robust.Server.ViewVariables
         ///     The session ID for this session. This is what the server and client use to talk about this session.
         /// </param>
         /// <param name="host">The view variables host owning this session.</param>
-        public ViewVariablesesSession(NetUserId playerUser, object o, uint sessionId, IViewVariablesHost host,
+        public ViewVariablesSession(NetUserId playerUser, object o, uint sessionId, IViewVariablesHost host,
             IRobustSerializer robustSerializer)
         {
             PlayerUser = playerUser;

Robust.Server/ViewVariables/ViewVariablesTrait.cs

@@ -13,7 +13,7 @@ namespace Robust.Server.ViewVariables
     ///     Traits define what behavior an object can have that VV cares about.
     ///     So like, is it enumerable, does it have VV accessible members. That kinda deal.
     ///     These are the "modular" way of extending VV.
-    ///     Server traits are bound to one <see cref="ViewVariablesesSession"/>, AKA one object.
+    ///     Server traits are bound to one <see cref="ViewVariablesSession"/>, AKA one object.
     /// </summary>
     internal abstract class ViewVariablesTrait
     {

Robust.Server/server_config.toml

@@ -32,7 +32,7 @@ enabled = true
 
 [game]
 hostname = "MyServer"
-# map = "Maps/saltern.yml"
+# map = "saltern"
 maxplayers = 64
 type = 1
 welcomemsg = "Welcome to the server!"

Robust.Shared.Maths/Color.cs

@@ -458,12 +458,15 @@ namespace Robust.Shared.Maths
             var c = max - min;
 
             var h = 0.0f;
-            if (max == rgb.R)
-                h = (rgb.G - rgb.B) / c;
-            else if (max == rgb.G)
-                h = (rgb.B - rgb.R) / c + 2.0f;
-            else if (max == rgb.B)
-                h = (rgb.R - rgb.G) / c + 4.0f;
+            if (c != 0)
+            {
+                if (max == rgb.R)
+                    h = (rgb.G - rgb.B) / c;
+                else if (max == rgb.G)
+                    h = (rgb.B - rgb.R) / c + 2.0f;
+                else if (max == rgb.B)
+                    h = (rgb.R - rgb.G) / c + 4.0f;
+            }
 
             var hue = h / 6.0f;
             if (hue < 0.0f)
@@ -566,12 +569,15 @@ namespace Robust.Shared.Maths
             var c = max - min;
 
             var h = 0.0f;
-            if (max == rgb.R)
-                h = (rgb.G - rgb.B) / c % 6.0f;
-            else if (max == rgb.G)
-                h = (rgb.B - rgb.R) / c + 2.0f;
-            else if (max == rgb.B)
-                h = (rgb.R - rgb.G) / c + 4.0f;
+            if (c != 0)
+            {
+                if (max == rgb.R)
+                    h = (rgb.G - rgb.B) / c % 6.0f;
+                else if (max == rgb.G)
+                    h = (rgb.B - rgb.R) / c + 2.0f;
+                else if (max == rgb.B)
+                    h = (rgb.R - rgb.G) / c + 4.0f;
+            }
 
             var hue = h * 60.0f / 360.0f;
 

Robust.Shared/Audio/Midi/MidiEvent.cs

@@ -1,118 +0,0 @@
-using System;
-using NFluidsynth;
-using Robust.Shared.Serialization;
-
-namespace Robust.Shared.Audio.Midi
-{
-    /// <summary>
-    ///     This class is a data representation of a Midi Event.
-    ///     It's 'compatible' with NFluidsynth's own MidiEvent class.
-    /// </summary>
-    [Serializable, NetSerializable]
-    public struct MidiEvent
-    {
-        public byte Type { get; set; }
-
-        public byte Channel { get; set; }
-
-        public byte Key { get; set; }
-
-        public byte Velocity { get; set; }
-
-        public int Control { get; set; }
-
-        public byte Value { get; set; }
-
-        public byte Program { get; set; }
-
-        public short Pitch { get; set; } // needs range from 0 to 16383
-
-        public uint Tick { get; set; }
-
-        public static explicit operator MidiEvent(NFluidsynth.MidiEvent midiEvent)
-        {
-            return new()
-            {
-                Type = (byte) midiEvent.Type,
-                Channel = (byte) midiEvent.Channel,
-                Control = midiEvent.Control,
-                Key = (byte) midiEvent.Key,
-                Pitch = (short) midiEvent.Pitch,
-                Program = (byte) midiEvent.Program,
-                Value = (byte) midiEvent.Value,
-                Velocity = (byte) midiEvent.Velocity,
-            };
-        }
-
-        public static implicit operator NFluidsynth.MidiEvent(MidiEvent midiEvent)
-        {
-            return new()
-            {
-                Type = midiEvent.Type,
-                Channel = midiEvent.Channel,
-                Control = midiEvent.Control,
-                Key = midiEvent.Key,
-                Pitch = midiEvent.Pitch,
-                Program = midiEvent.Program,
-                Value = midiEvent.Value,
-                Velocity = midiEvent.Velocity,
-            };
-        }
-
-        public override string ToString()
-        {
-            return $"{base.ToString()} >> TYPE: {Type} || CHANNEL: {Channel} || CONTROL: {Control} || KEY: {Key} || VELOCITY: {Velocity} || PITCH: {Pitch} || PROGRAM: {Program} || VALUE: {Value} <<";
-        }
-
-        public static implicit operator SequencerEvent(MidiEvent midiEvent)
-        {
-            var @event = new SequencerEvent();
-
-            switch (midiEvent.Type)
-            {
-                // NoteOff
-                case 128:
-                    @event.NoteOff(midiEvent.Channel, midiEvent.Key);
-                    break;
-
-                // NoteOn
-                case 144:
-                    if(midiEvent.Velocity != 0)
-                        @event.NoteOn(midiEvent.Channel, midiEvent.Key, midiEvent.Velocity);
-                    else
-                        @event.NoteOff(midiEvent.Channel, midiEvent.Key);
-                    break;
-
-                // After Touch
-                case 160:
-                    @event.KeyPressure(midiEvent.Channel, midiEvent.Key, midiEvent.Value);
-                    break;
-
-                // CC
-                case 176:
-                    @event.ControlChange(midiEvent.Channel, (short)midiEvent.Control, midiEvent.Value);
-                    break;
-
-                // Program Change
-                case 192:
-                    @event.ProgramChange(midiEvent.Channel, midiEvent.Program);
-                    break;
-
-                // Channel Pressure
-                case 208:
-                    @event.ChannelPressure(midiEvent.Channel, midiEvent.Value);
-                    break;
-
-                // Pitch Bend
-                case 224:
-                    @event.PitchBend(midiEvent.Channel, midiEvent.Pitch);
-                    break;
-            }
-
-            return @event;
-        }
-
-
-    }
-}
-

Robust.Shared/Audio/Midi/RobustMidiCommand.cs

@@ -0,0 +1,64 @@
+namespace Robust.Shared.Audio.Midi;
+
+/// <summary>
+///     Helper enum that keeps track of all MIDI commands that Robust currently supports.
+/// </summary>
+public enum RobustMidiCommand : byte
+{
+    /// <summary>
+    ///     NoteOff event.              <br/>
+    ///     data1 - Key,                <br/>
+    ///     data2 - undefined
+    /// </summary>
+    NoteOff          = 0x80,
+
+    /// <summary>
+    ///     NoteOn event.               <br/>
+    ///     data1 - Key,                <br/>
+    ///     data2 - Velocity
+    /// </summary>
+    NoteOn           = 0x90,
+
+    /// <summary>
+    ///     AfterTouch event.           <br/>
+    ///     data1 - Key,                <br/>
+    ///     data2 - Value
+    /// </summary>
+    /// <remarks>Also known as "KeyPressure".</remarks>
+    AfterTouch       = 0xA0,
+
+    /// <summary>
+    ///     ControlChange (CC) event.   <br/>
+    ///     data1 - Control,            <br/>
+    ///     data2 - Value
+    /// </summary>
+    ControlChange    = 0xB0,
+
+    /// <summary>
+    ///     ProgramChange event.        <br/>
+    ///     data1 - Program,            <br/>
+    ///     data2 - undefined
+    /// </summary>
+    ProgramChange    = 0xC0,
+
+    /// <summary>
+    ///     ChannelPressure event.      <br/>
+    ///     data1 - Value,              <br/>
+    ///     data2 - undefined
+    /// </summary>
+    ChannelPressure  = 0xD0,
+
+    /// <summary>
+    ///     PitchBend event.            <br/>
+    ///     data1 - Lower Pitch Nibble, <br/>
+    ///     data2 - Higher Pitch Nibble
+    /// </summary>
+    PitchBend        = 0xE0,
+
+    /// <summary>
+    ///     SystemMessage event.        <br/>
+    ///     data1 - Control             <br/>
+    ///     data2 - undefined
+    /// </summary>
+    SystemMessage    = 0xF0,
+}

Robust.Shared/Audio/Midi/RobustMidiEvent.cs

@@ -0,0 +1,94 @@
+using System;
+using Robust.Shared.Serialization;
+
+namespace Robust.Shared.Audio.Midi
+{
+    /// <summary>
+    ///     This class is a lightweight data representation of a Midi Event.
+    /// </summary>
+    [Serializable, NetSerializable]
+    public readonly struct RobustMidiEvent
+    {
+        #region Data
+
+        /// <summary>
+        ///     Byte that stores both Command Type and Channel.
+        /// </summary>
+        public readonly byte Status;
+
+        public readonly byte Data1;
+        public readonly byte Data2;
+
+        /// <summary>
+        ///     Sequencer tick to schedule this event at.
+        /// </summary>
+        public readonly uint Tick;
+
+        #endregion
+
+        #region Properties
+
+        public int Channel => Status & 0x0F; // Low nibble.
+        public int Command => Status & 0xF0; // High nibble.
+        public RobustMidiCommand MidiCommand => (RobustMidiCommand) Command;
+        public byte Key => Data1;
+        public byte Velocity => Data2;
+        public byte Control => Data1;
+        public byte Value => Data2;
+        public int Pitch => (Data2 << 8) | Data1;
+        public byte Pressure => Data1;
+        public byte Program => Data1;
+
+        #endregion
+
+        public RobustMidiEvent(byte status, byte data1, byte data2, uint tick)
+        {
+            Status = status;
+            Data1 = data1;
+            Data2 = data2;
+            Tick = tick;
+        }
+
+        public override string ToString()
+        {
+            return $"{base.ToString()} >> CHANNEL: 0x{Channel:X} || COMMAND: 0x{Command:X} {MidiCommand} || DATA1: 0x{Data1:X} || DATA2: 0x{Data2:X} || TICK: {Tick} <<";
+        }
+
+        #region Static Methods
+
+        /// <summary>
+        ///     Returns a status byte given a channel byte and a command type byte.
+        /// </summary>
+        public static byte MakeStatus(byte channel, byte command)
+        {
+            return (byte) (command | channel);
+        }
+
+        /// <summary>
+        ///     Creates and returns an event to turn all notes off on a given channel.
+        /// </summary>
+        public static RobustMidiEvent AllNotesOff(byte channel, uint tick)
+        {
+            return new RobustMidiEvent(MakeStatus(channel, (byte)RobustMidiCommand.SystemMessage), 0x0B, 0x0, tick);
+        }
+
+        /// <summary>
+        ///     Creates and returns an event to reset all controllers.
+        /// </summary>
+        public static RobustMidiEvent ResetAllControllers(uint tick)
+        {
+            return new RobustMidiEvent((byte)RobustMidiCommand.ControlChange, 0x79, 0x0, tick);
+        }
+
+        /// <summary>
+        ///     Creates and returns a system reset event.
+        /// </summary>
+        public static RobustMidiEvent SystemReset(uint tick)
+        {
+            return new RobustMidiEvent((byte) RobustMidiCommand.SystemMessage | 0x0F, 0x0, 0x0, tick);
+        }
+
+        #endregion
+    }
+}
+

Robust.Shared/CVars.cs

@@ -136,6 +136,12 @@ namespace Robust.Shared
         public static readonly CVarDef<int> NetPVSEntityBudget =
             CVarDef.Create("net.pvs_budget", 50, CVar.ARCHIVE | CVar.REPLICATED);
 
+        /// <summary>
+        /// ZSTD compression level to use when compressing game states.
+        /// </summary>
+        public static readonly CVarDef<int> NetPVSCompressLevel =
+            CVarDef.Create("net.pvs_compress_level", 3, CVar.SERVERONLY);
+
         /// <summary>
         /// Log late input messages from clients.
         /// </summary>
@@ -188,6 +194,33 @@ namespace Robust.Shared
         public static readonly CVarDef<string> NetLidgrenAppIdentifier =
             CVarDef.Create("net.lidgren_app_identifier", "RobustToolbox");
 
+#if DEBUG
+        /// <summary>
+        /// Add random fake network loss to all outgoing UDP network packets, as a ratio of how many packets to drop.
+        /// 0 = no packet loss, 1 = all packets dropped
+        /// </summary>
+        public static readonly CVarDef<float> NetFakeLoss = CVarDef.Create("net.fakeloss", 0f, CVar.CHEAT);
+
+        /// <summary>
+        /// Add fake extra delay to all outgoing UDP network packets, in seconds.
+        /// </summary>
+        /// <seealso cref="NetFakeLagRand"/>
+        public static readonly CVarDef<float> NetFakeLagMin = CVarDef.Create("net.fakelagmin", 0f, CVar.CHEAT);
+
+        /// <summary>
+        /// Add fake extra random delay to all outgoing UDP network packets, in seconds.
+        /// The actual delay added for each packet is random between 0 and the specified value.
+        /// </summary>
+        /// <seealso cref="NetFakeLagMin"/>
+        public static readonly CVarDef<float> NetFakeLagRand = CVarDef.Create("net.fakelagrand", 0f, CVar.CHEAT);
+
+        /// <summary>
+        /// Add random fake duplicates to all outgoing UDP network packets, as a ratio of how many packets to duplicate.
+        /// 0 = no packets duplicated, 1 = all packets duplicated.
+        /// </summary>
+        public static readonly CVarDef<float> NetFakeDuplicates = CVarDef.Create("net.fakeduplicates", 0f, CVar.CHEAT);
+#endif
+
         /**
          * SUS
          */
@@ -218,33 +251,6 @@ namespace Robust.Shared
         public static readonly CVarDef<int> SysGameThreadPriority =
             CVarDef.Create("sys.game_thread_priority", (int) ThreadPriority.AboveNormal);
 
-#if DEBUG
-        /// <summary>
-        /// Add random fake network loss to all outgoing UDP network packets, as a ratio of how many packets to drop.
-        /// 0 = no packet loss, 1 = all packets dropped
-        /// </summary>
-        public static readonly CVarDef<float> NetFakeLoss = CVarDef.Create("net.fakeloss", 0f, CVar.CHEAT);
-
-        /// <summary>
-        /// Add fake extra delay to all outgoing UDP network packets, in seconds.
-        /// </summary>
-        /// <seealso cref="NetFakeLagRand"/>
-        public static readonly CVarDef<float> NetFakeLagMin = CVarDef.Create("net.fakelagmin", 0f, CVar.CHEAT);
-
-        /// <summary>
-        /// Add fake extra random delay to all outgoing UDP network packets, in seconds.
-        /// The actual delay added for each packet is random between 0 and the specified value.
-        /// </summary>
-        /// <seealso cref="NetFakeLagMin"/>
-        public static readonly CVarDef<float> NetFakeLagRand = CVarDef.Create("net.fakelagrand", 0f, CVar.CHEAT);
-
-        /// <summary>
-        /// Add random fake duplicates to all outgoing UDP network packets, as a ratio of how many packets to duplicate.
-        /// 0 = no packets duplicated, 1 = all packets duplicated.
-        /// </summary>
-        public static readonly CVarDef<float> NetFakeDuplicates = CVarDef.Create("net.fakeduplicates", 0f, CVar.CHEAT);
-#endif
-
         /*
          * METRICS
          */
@@ -426,12 +432,30 @@ namespace Robust.Shared
         public static readonly CVarDef<string> BuildDownloadUrl =
             CVarDef.Create("build.download_url", string.Empty, CVar.SERVERONLY);
 
+        /// <summary>
+        /// URL of the content manifest the launcher should download to connect to this server.
+        /// </summary>
+        public static readonly CVarDef<string> BuildManifestUrl =
+            CVarDef.Create("build.manifest_url", string.Empty, CVar.SERVERONLY);
+
+        /// <summary>
+        /// URL at which the launcher can download the manifest game files.
+        /// </summary>
+        public static readonly CVarDef<string> BuildManifestDownloadUrl =
+            CVarDef.Create("build.manifest_download_url", string.Empty, CVar.SERVERONLY);
+
         /// <summary>
         /// SHA-256 hash of the content pack hosted at <c>build.download_url</c>
         /// </summary>
         public static readonly CVarDef<string> BuildHash =
             CVarDef.Create("build.hash", "", CVar.SERVERONLY);
 
+        /// <summary>
+        /// SHA-256 hash of the manifest hosted at <c>build.manifest_url</c>
+        /// </summary>
+        public static readonly CVarDef<string> BuildManifestHash =
+            CVarDef.Create("build.manifest_hash", "", CVar.SERVERONLY);
+
         /*
          * WATCHDOG
          */
@@ -1072,5 +1096,67 @@ namespace Robust.Shared
         /// </summary>
         public static readonly CVarDef<int> HubAdvertiseInterval =
             CVarDef.Create("hub.advertise_interval", 120, CVar.SERVERONLY);
+
+        /*
+         * ACZ
+         */
+
+        /// <summary>
+        /// Whether to use stream compression instead of per-file compression when transmitting ACZ data.
+        /// Enabling stream compression significantly reduces bandwidth usage of downloads,
+        /// but increases server and launcher CPU load. It also makes final files stored on the client compressed less.
+        /// </summary>
+        public static readonly CVarDef<bool> AczStreamCompress =
+            CVarDef.Create("acz.stream_compress", false, CVar.SERVERONLY);
+
+        /// <summary>
+        /// ZSTD Compression level to use when doing ACZ stream compressed.
+        /// </summary>
+        public static readonly CVarDef<int> AczStreamCompressLevel =
+            CVarDef.Create("acz.stream_compress_level", 3, CVar.SERVERONLY);
+
+        /// <summary>
+        /// Whether to do compression on individual files for ACZ downloads.
+        /// Automatically forced off if stream compression is enabled.
+        /// </summary>
+        public static readonly CVarDef<bool> AczBlobCompress =
+            CVarDef.Create("acz.blob_compress", true, CVar.SERVERONLY);
+
+        /// <summary>
+        /// ZSTD Compression level to use for individual file compression.
+        /// </summary>
+        public static readonly CVarDef<int> AczBlobCompressLevel =
+            CVarDef.Create("acz.blob_compress_level", 14, CVar.SERVERONLY);
+
+        // Could consider using a ratio for this?
+        /// <summary>
+        /// Amount of bytes that need to be saved by compression for the compression to be "worth it".
+        /// </summary>
+        public static readonly CVarDef<int> AczBlobCompressSaveThreshold =
+            CVarDef.Create("acz.blob_compress_save_threshold", 14, CVar.SERVERONLY);
+
+        /// <summary>
+        /// Whether to ZSTD compress the ACZ manifest.
+        /// If this is enabled (the default) then non-compressed manifest requests will be decompressed live.
+        /// </summary>
+        public static readonly CVarDef<bool> AczManifestCompress =
+            CVarDef.Create("acz.manifest_compress", true, CVar.SERVERONLY);
+
+        /// <summary>
+        /// Compression level for ACZ manifest compression.
+        /// </summary>
+        public static readonly CVarDef<int> AczManifestCompressLevel =
+            CVarDef.Create("acz.manifest_compress_level", 14, CVar.SERVERONLY);
+
+        /*
+         * THREAD
+         */
+
+        /// <summary>
+        /// The nominal parallel processing count to use for parallelized operations.
+        /// The default of 0 automatically selects the system's processor count.
+        /// </summary>
+        public static readonly CVarDef<int> ThreadParallelCount =
+            CVarDef.Create("thread.parallel_count", 0);
     }
 }

Robust.Shared/Collections/OverflowQueue.cs

@@ -0,0 +1,148 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+
+namespace Robust.Shared.Collections;
+
+/// <summary>
+/// A fixed-size queue that discards the oldest entry if a new entry is enqueued when the queue is full.
+/// </summary>
+/// <typeparam name="T"></typeparam>
+public sealed class OverflowQueue<T>
+{
+    private readonly T[] _queue;
+    private int _currentIdx = 0;
+    private int _length = 0;
+    /// <summary>
+    /// The size of the queue-buffer.
+    /// </summary>
+    public int Size => _queue.Length;
+
+    /// <param name="size">size of the queue-buffer</param>
+    public OverflowQueue(int size)
+    {
+        _queue = new T[size];
+    }
+
+    /// <summary>
+    /// Enqueues the <paramref name="item"/>. Overrides the oldest item if the queue is full.
+    /// </summary>
+    /// <param name="item">The item to enqueue</param>
+    public void Enqueue(T item)
+    {
+        _queue[_currentIdx++] = item;
+        if(_length < Size)
+            _length++;
+
+        if (_currentIdx == Size)
+        {
+            _currentIdx = 0;
+        }
+    }
+
+    /// <summary>
+    /// Removes the item at the head of the queue and returns it. If the queue is empty, this method throws an InvalidOperationException.
+    /// </summary>
+    /// <returns>The dequeued item.</returns>
+    /// <exception cref="InvalidOperationException">Thrown if the queue is empty.</exception>
+    public T Dequeue()
+    {
+        if (!TryDequeue(out var item))
+        {
+            throw new InvalidOperationException($"{nameof(OverflowQueue<T>)} has no more items to dequeue.");
+        }
+
+        return item;
+    }
+
+    /// <summary>
+    /// Tries to dequeue an item.
+    /// </summary>
+    /// <param name="item">The item which got dequeued. Null if the queue was empty</param>
+    /// <returns>True if an item was dequeued, false if not.</returns>
+    public bool TryDequeue([NotNullWhen(true)] out T? item)
+    {
+        if (_length == 0)
+        {
+            item = default;
+            return false;
+        }
+
+        item = _queue[GetCurrentIndex()]!;
+        _length--;
+        return true;
+    }
+
+    private int GetCurrentIndex()
+    {
+        Debug.Assert(_length > 0);
+        var idx = _currentIdx - _length;
+        if (idx < 0)
+        {
+            return idx + Size;
+        }
+
+        return idx;
+    }
+
+    /// <summary>
+    /// Returns the item at the head of the queue. The object remains in the queue. If the queue is empty, this method throws an InvalidOperationException.
+    /// </summary>
+    /// <returns>The item at the head of the queue.</returns>
+    /// <exception cref="InvalidOperationException">Thrown if the queue is empty.</exception>
+    public T Peek()
+    {
+        if (_length == 0)
+        {
+            throw new InvalidOperationException($"{nameof(OverflowQueue<T>)} has no more items to dequeue.");
+        }
+
+        return _queue[GetCurrentIndex()];
+    }
+
+    /// <summary>
+    /// Returns true if the queue contains at least one object equal to item. Equality is determined using EqualityComparer<T>.Default.Equals().
+    /// </summary>
+    /// <param name="item">Item to look for.</param>
+    /// <returns>True if the queue contains the item, false if not.</returns>
+    public bool Contains(T item)
+    {
+        for (int i = 0; i < _length; i++)
+        {
+            var actualIndex = _currentIdx + i;
+            if (actualIndex >= _length)
+                actualIndex -= _length;
+            if (EqualityComparer<T>.Default.Equals(item, _queue[actualIndex])) return true;
+        }
+        return false;
+    }
+
+    /// <summary>
+    /// Returns the queue contents first to last as an array.
+    /// </summary>
+    /// <returns>The array containing the queue contents.</returns>
+    public T[] ToArray()
+    {
+        if (_length == 0)
+        {
+            return Array.Empty<T>();
+        }
+
+        var res = new T[_length];
+
+        var startIdx = _currentIdx - _length;
+        if (startIdx < 0)
+        {
+            Array.Copy(_queue, startIdx + Size, res, 0, -1 * startIdx);
+            Array.Copy(_queue, 0, res, -1 * startIdx, startIdx + Size);
+        }
+        else
+        {
+            Array.Copy(_queue, startIdx, res, 0, _length);
+        }
+
+        return res;
+    }
+}

Robust.Shared/Configuration/ConfigurationManager.cs

@@ -4,9 +4,11 @@ using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Reflection;
+using System.Threading;
 using Nett;
 using Robust.Shared.Log;
 using Robust.Shared.Utility;
+using Robust.Shared.Utility.Collections;
 
 namespace Robust.Shared.Configuration
 {
@@ -21,6 +23,8 @@ namespace Robust.Shared.Configuration
         private string? _configFile;
         protected bool _isServer;
 
+        protected readonly ReaderWriterLockSlim Lock = new();
+
         /// <summary>
         ///     Constructs a new ConfigurationManager.
         /// </summary>
@@ -35,6 +39,8 @@ namespace Robust.Shared.Configuration
 
         public virtual void Shutdown()
         {
+            using var _ = Lock.WriteGuard();
+
             _configVars.Clear();
             _configFile = null;
         }
@@ -46,7 +52,18 @@ namespace Robust.Shared.Configuration
             {
                 var tblRoot = Toml.ReadFile(configFile);
 
-                ProcessTomlObject(tblRoot);
+                var callbackEvents = new ValueList<ValueChangedInvoke>();
+
+                // Ensure callbacks are raised OUTSIDE the write lock.
+                using (Lock.WriteGuard())
+                {
+                    ProcessTomlObject(tblRoot, ref callbackEvents);
+                }
+
+                foreach (var callback in callbackEvents)
+                {
+                    InvokeValueChanged(callback);
+                }
 
                 _configFile = configFile;
                 Logger.InfoS("cfg", $"Configuration Loaded from '{Path.GetFullPath(configFile)}'");
@@ -66,8 +83,12 @@ namespace Robust.Shared.Configuration
         /// A recursive function that walks over the config tree, transforming all key nodes into CVars.
         /// </summary>
         /// <param name="obj">The root table of the TOML document.</param>
+        /// <param name="changedInvokes">List of CVars that will need to have their InvokeValueChanged ran.</param>
         /// <param name="tablePath">For internal use only, the current path to the node.</param>
-        private void ProcessTomlObject(TomlObject obj, string tablePath = "")
+        private void ProcessTomlObject(
+            TomlObject obj,
+            ref ValueList<ValueChangedInvoke> changedInvokes,
+            string tablePath = "")
         {
             if (obj is TomlTable table) // this is a table
             {
@@ -80,7 +101,7 @@ namespace Robust.Shared.Configuration
                     else
                         newPath = tablePath + kvTml.Key;
 
-                    ProcessTomlObject(kvTml.Value, newPath);
+                    ProcessTomlObject(kvTml.Value, ref changedInvokes, newPath);
                 }
             }
             else // this is a key, add CVar
@@ -91,7 +112,8 @@ namespace Robust.Shared.Configuration
                 {
                     // overwrite the value with the saved one
                     cfgVar.Value = tomlValue;
-                    InvokeValueChanged(cfgVar, cfgVar.Value);
+                    if (SetupInvokeValueChanged(cfgVar, tomlValue) is { } invoke)
+                        changedInvokes.Add(invoke);
                 }
                 else
                 {
@@ -118,73 +140,76 @@ namespace Robust.Shared.Configuration
             {
                 var tblRoot = Toml.Create();
 
-                foreach (var (name, cVar) in _configVars)
+                using (Lock.ReadGuard())
                 {
-                    var value = cVar.Value;
-                    if (value == null && cVar.Registered)
+                    foreach (var (name, cVar) in _configVars)
                     {
-                        value = cVar.DefaultValue;
-                    }
-
-                    if (value == null)
-                    {
-                        Logger.ErrorS("cfg",
-                            $"CVar {name} has no value or default value, was the default value registered as null?");
-                        continue;
-                    }
-
-                    // Don't write if Archive flag is not set.
-                    // Don't write if the cVar is the default value.
-                    if (!cVar.ConfigModified &&
-                        (cVar.Flags & CVar.ARCHIVE) == 0 || value.Equals(cVar.DefaultValue))
-                    {
-                        continue;
-                    }
-
-                    var keyIndex = name.LastIndexOf(TABLE_DELIMITER);
-                    var tblPath = name.Substring(0, keyIndex).Split(TABLE_DELIMITER);
-                    var keyName = name.Substring(keyIndex + 1);
-
-                    // locate the Table in the config tree
-                    var table = tblRoot;
-                    foreach (var curTblName in tblPath)
-                    {
-                        if (!table.TryGetValue(curTblName, out TomlObject tblObject))
+                        var value = cVar.Value;
+                        if (value == null && cVar.Registered)
                         {
-                            tblObject = table.Add(curTblName, new Dictionary<string, TomlObject>()).Added;
+                            value = cVar.DefaultValue;
                         }
 
-                        table = tblObject as TomlTable ?? throw new InvalidConfigurationException(
-                            $"[CFG] Object {curTblName} is being used like a table, but it is a {tblObject}. Are your CVar names formed properly?");
-                    }
+                        if (value == null)
+                        {
+                            Logger.ErrorS("cfg",
+                                $"CVar {name} has no value or default value, was the default value registered as null?");
+                            continue;
+                        }
 
-                    //runtime unboxing, either this or generic hell... ¯\_(ツ)_/¯
-                    switch (value)
-                    {
-                        case Enum val:
-                            table.Add(keyName, (int) (object) val); // asserts Enum value != (ulong || long)
-                            break;
-                        case int val:
-                            table.Add(keyName, val);
-                            break;
-                        case long val:
-                            table.Add(keyName, val);
-                            break;
-                        case bool val:
-                            table.Add(keyName, val);
-                            break;
-                        case string val:
-                            table.Add(keyName, val);
-                            break;
-                        case float val:
-                            table.Add(keyName, val);
-                            break;
-                        case double val:
-                            table.Add(keyName, val);
-                            break;
-                        default:
-                            Logger.WarningS("cfg", $"Cannot serialize '{name}', unsupported type.");
-                            break;
+                        // Don't write if Archive flag is not set.
+                        // Don't write if the cVar is the default value.
+                        if (!cVar.ConfigModified &&
+                            (cVar.Flags & CVar.ARCHIVE) == 0 || value.Equals(cVar.DefaultValue))
+                        {
+                            continue;
+                        }
+
+                        var keyIndex = name.LastIndexOf(TABLE_DELIMITER);
+                        var tblPath = name.Substring(0, keyIndex).Split(TABLE_DELIMITER);
+                        var keyName = name.Substring(keyIndex + 1);
+
+                        // locate the Table in the config tree
+                        var table = tblRoot;
+                        foreach (var curTblName in tblPath)
+                        {
+                            if (!table.TryGetValue(curTblName, out TomlObject tblObject))
+                            {
+                                tblObject = table.Add(curTblName, new Dictionary<string, TomlObject>()).Added;
+                            }
+
+                            table = tblObject as TomlTable ?? throw new InvalidConfigurationException(
+                                $"[CFG] Object {curTblName} is being used like a table, but it is a {tblObject}. Are your CVar names formed properly?");
+                        }
+
+                        //runtime unboxing, either this or generic hell... ¯\_(ツ)_/¯
+                        switch (value)
+                        {
+                            case Enum val:
+                                table.Add(keyName, (int)(object)val); // asserts Enum value != (ulong || long)
+                                break;
+                            case int val:
+                                table.Add(keyName, val);
+                                break;
+                            case long val:
+                                table.Add(keyName, val);
+                                break;
+                            case bool val:
+                                table.Add(keyName, val);
+                                break;
+                            case string val:
+                                table.Add(keyName, val);
+                                break;
+                            case float val:
+                                table.Add(keyName, val);
+                                break;
+                            case double val:
+                                table.Add(keyName, val);
+                                break;
+                            default:
+                                Logger.WarningS("cfg", $"Cannot serialize '{name}', unsupported type.");
+                                break;
+                        }
                     }
                 }
 
@@ -220,6 +245,8 @@ namespace Robust.Shared.Configuration
                 return;
             }
 
+            using var _ = Lock.WriteGuard();
+
             if (_configVars.TryGetValue(name, out var cVar))
             {
                 if (cVar.Registered)
@@ -253,12 +280,16 @@ namespace Robust.Shared.Configuration
         public void OnValueChanged<T>(string name, Action<T> onValueChanged, bool invokeImmediately = false)
             where T : notnull
         {
-            var reg = _configVars[name];
-            var exDel = (Action<T>?) reg.ValueChanged;
-            exDel += onValueChanged;
-            reg.ValueChanged = exDel;
 
-            reg.ValueChangedInvoker ??= (del, v) => ((Action<T>) del)((T) v);
+            using (Lock.WriteGuard())
+            {
+                var reg = _configVars[name];
+                var exDel = (Action<T>?) reg.ValueChanged;
+                exDel += onValueChanged;
+                reg.ValueChanged = exDel;
+
+                reg.ValueChangedInvoker ??= (del, v) => ((Action<T>) del)((T) v);
+            }
 
             if (invokeImmediately)
             {
@@ -273,6 +304,8 @@ namespace Robust.Shared.Configuration
 
         public void UnsubValueChanged<T>(string name, Action<T> onValueChanged) where T : notnull
         {
+            using var _ = Lock.WriteGuard();
+
             var reg = _configVars[name];
             var exDel = (Action<T>?) reg.ValueChanged;
             exDel -= onValueChanged;
@@ -315,13 +348,17 @@ namespace Robust.Shared.Configuration
         /// <inheritdoc />
         public bool IsCVarRegistered(string name)
         {
+            using var _ = Lock.ReadGuard();
             return _configVars.TryGetValue(name, out var cVar) && cVar.Registered;
         }
 
         /// <inheritdoc />
         public IEnumerable<string> GetRegisteredCVars()
         {
-            return _configVars.Select(p => p.Key);
+            using var _ = Lock.ReadGuard();
+            // Have to .ToArray() so the lock is held for the whole iteration operation.
+            // This function is only currently used for the cvar ? command so I'm not too worried.
+            return _configVars.Select(p => p.Key).ToArray();
         }
 
         /// <inheritdoc />
@@ -332,21 +369,29 @@ namespace Robust.Shared.Configuration
 
         private void SetCVarInternal(string name, object value)
         {
-            //TODO: Make flags work, required non-derpy net system.
-            if (_configVars.TryGetValue(name, out var cVar) && cVar.Registered)
-            {
-                if (!Equals(cVar.OverrideValueParsed ?? cVar.Value, value))
-                {
-                    // Setting an overriden var just turns off the override, basically.
-                    cVar.OverrideValue = null;
-                    cVar.OverrideValueParsed = null;
+            ValueChangedInvoke? invoke = null;
 
-                    cVar.Value = value;
-                    InvokeValueChanged(cVar, value);
+            using (Lock.WriteGuard())
+            {
+                //TODO: Make flags work, required non-derpy net system.
+                if (_configVars.TryGetValue(name, out var cVar) && cVar.Registered)
+                {
+                    if (!Equals(cVar.OverrideValueParsed ?? cVar.Value, value))
+                    {
+                        // Setting an overriden var just turns off the override, basically.
+                        cVar.OverrideValue = null;
+                        cVar.OverrideValueParsed = null;
+
+                        cVar.Value = value;
+                        invoke = SetupInvokeValueChanged(cVar, value);
+                    }
                 }
+                else
+                    throw new InvalidConfigurationException($"Trying to set unregistered variable '{name}'");
             }
-            else
-                throw new InvalidConfigurationException($"Trying to set unregistered variable '{name}'");
+
+            if (invoke != null)
+                InvokeValueChanged(invoke.Value);
         }
 
         public void SetCVar<T>(CVarDef<T> def, T value) where T : notnull
@@ -357,6 +402,7 @@ namespace Robust.Shared.Configuration
         /// <inheritdoc />
         public T GetCVar<T>(string name)
         {
+            using var _ = Lock.ReadGuard();
             if (_configVars.TryGetValue(name, out var cVar) && cVar.Registered)
                 //TODO: Make flags work, required non-derpy net system.
                 return (T) (GetConfigVarValue(cVar))!;
@@ -371,6 +417,7 @@ namespace Robust.Shared.Configuration
 
         public Type GetCVarType(string name)
         {
+            using var _ = Lock.ReadGuard();
             if (!_configVars.TryGetValue(name, out var cVar) || !cVar.Registered)
             {
                 throw new InvalidConfigurationException($"Trying to get type of unregistered variable '{name}'");
@@ -387,24 +434,35 @@ namespace Robust.Shared.Configuration
 
         public void OverrideConVars(IEnumerable<(string key, string value)> cVars)
         {
-            foreach (var (key, value) in cVars)
+            var invokes = new ValueList<ValueChangedInvoke>();
+
+            using (Lock.WriteGuard())
             {
-                if (_configVars.TryGetValue(key, out var cfgVar))
+                foreach (var (key, value) in cVars)
                 {
-                    cfgVar.OverrideValue = value;
-                    if (cfgVar.Registered)
+                    if (_configVars.TryGetValue(key, out var cfgVar))
                     {
-                        cfgVar.OverrideValueParsed = ParseOverrideValue(value, cfgVar.DefaultValue?.GetType());
-                        InvokeValueChanged(cfgVar, cfgVar.OverrideValueParsed);
+                        cfgVar.OverrideValue = value;
+                        if (cfgVar.Registered)
+                        {
+                            cfgVar.OverrideValueParsed = ParseOverrideValue(value, cfgVar.DefaultValue?.GetType());
+                            if (SetupInvokeValueChanged(cfgVar, cfgVar.OverrideValueParsed) is { } invoke)
+                                invokes.Add(invoke);
+                        }
+                    }
+                    else
+                    {
+                        //or add another unregistered CVar
+                        //Note: the defaultValue is arbitrarily 0, it will get overwritten when the cvar is registered.
+                        var cVar = new ConfigVar(key, 0, CVar.NONE) {OverrideValue = value};
+                        _configVars.Add(key, cVar);
                     }
                 }
-                else
-                {
-                    //or add another unregistered CVar
-                    //Note: the defaultValue is arbitrarily 0, it will get overwritten when the cvar is registered.
-                    var cVar = new ConfigVar(key, 0, CVar.NONE) {OverrideValue = value};
-                    _configVars.Add(key, cVar);
-                }
+            }
+
+            foreach (var invoke in invokes)
+            {
+                InvokeValueChanged(invoke);
             }
         }
 
@@ -461,9 +519,17 @@ namespace Robust.Shared.Configuration
             }
         }
 
-        private static void InvokeValueChanged(ConfigVar var, object value)
+        private static void InvokeValueChanged(ValueChangedInvoke invoke)
         {
-            var.ValueChangedInvoker?.Invoke(var.ValueChanged!, value);
+            invoke.Invoker.Invoke(invoke.ValueChanged, invoke.Value);
+        }
+
+        private static ValueChangedInvoke? SetupInvokeValueChanged(ConfigVar var, object value)
+        {
+            if (var.ValueChangedInvoker == null)
+                return null;
+
+            return new ValueChangedInvoke(var.ValueChangedInvoker, var.ValueChanged!, value);
         }
 
         /// <summary>
@@ -530,6 +596,14 @@ namespace Robust.Shared.Configuration
             public string? OverrideValue { get; set; }
             public object? OverrideValueParsed { get; set; }
         }
+
+        /// <summary>
+        /// All data we need to invoke a deferred ValueChanged handler outside of a write lock.
+        /// </summary>
+        private record struct ValueChangedInvoke(
+            Action<Delegate, object> Invoker,
+            Delegate ValueChanged,
+            object Value);
     }
 
     [Serializable]

Robust.Shared/Configuration/IConfigurationManager.cs

@@ -6,6 +6,13 @@ namespace Robust.Shared.Configuration
     /// <summary>
     /// Stores and manages global configuration variables.
     /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Accessing (getting/setting) main CVars is thread safe.
+    /// Note that value-changed callbacks are ran synchronously from the thread using <see cref="SetCVar"/>,
+    /// so it is not recommended to modify CVars from other threads.
+    /// </para>
+    /// </remarks>
     public interface IConfigurationManager
     {
         /// <summary>

Robust.Shared/Configuration/NetConfigurationManager.cs

@@ -190,6 +190,8 @@ namespace Robust.Shared.Configuration
                 return;
             }
 
+            using var _ = Lock.ReadGuard();
+
             foreach (var (name, value) in networkedVars)
             {
                 if (!_configVars.TryGetValue(name, out var cVar))
@@ -219,6 +221,8 @@ namespace Robust.Shared.Configuration
         /// <inheritdoc />
         public T GetClientCVar<T>(INetChannel channel, string name)
         {
+            using var _ = Lock.ReadGuard();
+
             if (!_configVars.TryGetValue(name, out var cVar) || !cVar.Registered)
                 throw new InvalidConfigurationException($"Trying to get unregistered variable '{name}'");
 
@@ -233,43 +237,46 @@ namespace Robust.Shared.Configuration
         /// <inheritdoc />
         public override void SetCVar(string name, object value)
         {
-            if (_configVars.TryGetValue(name, out var cVar) && cVar.Registered)
+            CVar flags;
+            using (Lock.ReadGuard())
             {
-                if (_netManager.IsClient)
+                if (_configVars.TryGetValue(name, out var cVar) && cVar.Registered)
                 {
-                    if (_netManager.IsConnected)
+                    flags = cVar.Flags;
+                    if (_netManager.IsClient)
                     {
-                        if ((cVar.Flags & CVar.NOT_CONNECTED) != 0)
+                        if (_netManager.IsConnected)
                         {
-                            Logger.WarningS("cfg", $"'{name}' can only be changed when not connected to a server.");
+                            if ((cVar.Flags & CVar.NOT_CONNECTED) != 0)
+                            {
+                                Logger.WarningS("cfg", $"'{name}' can only be changed when not connected to a server.");
+                                return;
+                            }
+                        }
+
+                        if ((cVar.Flags & CVar.SERVER) != 0)
+                        {
+                            Logger.WarningS("cfg", $"Only the server can change '{name}'.");
                             return;
                         }
                     }
-
-                    if ((cVar.Flags & CVar.SERVER) != 0)
-                    {
-                        Logger.WarningS("cfg", $"Only the server can change '{name}'.");
-                        return;
-                    }
                 }
-            }
-            else
-            {
-                throw new InvalidConfigurationException($"Trying to set unregistered variable '{name}'");
+                else
+                {
+                    throw new InvalidConfigurationException($"Trying to set unregistered variable '{name}'");
+                }
             }
 
             // Actually set the CVar
             base.SetCVar(name, value);
 
-            var cvar = _configVars[name];
+            if ((flags & CVar.REPLICATED) == 0)
+                return;
 
             // replicate if needed
             if (_netManager.IsClient)
             {
-                if ((cvar.Flags & CVar.REPLICATED) == 0)
-                    return;
-
-                var msg = _netManager.CreateNetMessage<MsgConVars>();
+                var msg = new MsgConVars();
                 msg.Tick = _timing.CurTick;
                 msg.NetworkedVars = new List<(string name, object value)>
                 {
@@ -279,10 +286,7 @@ namespace Robust.Shared.Configuration
             }
             else // Server
             {
-                if ((cvar.Flags & CVar.REPLICATED) == 0)
-                    return;
-
-                var msg = _netManager.CreateNetMessage<MsgConVars>();
+                var msg = new MsgConVars();
                 msg.Tick = _timing.CurTick;
                 msg.NetworkedVars = new List<(string name, object value)>
                 {
@@ -300,7 +304,7 @@ namespace Robust.Shared.Configuration
 
             Logger.InfoS("cfg", $"{client}: Sending server info...");
 
-            var msg = _netManager.CreateNetMessage<MsgConVars>();
+            var msg = new MsgConVars();
             msg.Tick = _timing.CurTick;
             msg.NetworkedVars = GetReplicatedVars();
             _netManager.ServerSendMessage(msg, client);
@@ -314,7 +318,7 @@ namespace Robust.Shared.Configuration
 
             Logger.InfoS("cfg", "Sending client info...");
 
-            var msg = _netManager.CreateNetMessage<MsgConVars>();
+            var msg = new MsgConVars();
             msg.Tick = default;
             msg.NetworkedVars = GetReplicatedVars();
             _netManager.ClientSendMessage(msg);
@@ -327,6 +331,8 @@ namespace Robust.Shared.Configuration
 
         private List<(string name, object value)> GetReplicatedVars()
         {
+            using var _ = Lock.ReadGuard();
+
             var nwVars = new List<(string name, object value)>();
 
             foreach (var cVar in _configVars.Values)

Robust.Shared/ContentPack/AssemblyTypeChecker.cs

@@ -193,6 +193,10 @@ namespace Robust.Shared.ContentPack
 
             _sawmill.Debug($"Unmanaged methods... {fullStopwatch.ElapsedMilliseconds}ms");
 
+            CheckNoTypeAbuse(reader, errors);
+
+            _sawmill.Debug($"Type abuse... {fullStopwatch.ElapsedMilliseconds}ms");
+
             CheckMemberReferences(loadedConfig, members, errors);
 
             foreach (var error in errors)
@@ -311,6 +315,27 @@ namespace Robust.Shared.ContentPack
             }
         }
 
+        private static void CheckNoTypeAbuse(MetadataReader reader, ConcurrentBag<SandboxError> errors)
+        {
+            foreach (var typeDefHandle in reader.TypeDefinitions)
+            {
+                var typeDef = reader.GetTypeDefinition(typeDefHandle);
+                if ((typeDef.Attributes & TypeAttributes.ExplicitLayout) != 0)
+                {
+                    // The C# compiler emits explicit layout types for some array init logic. These have no fields.
+                    // Only ban explicit layout if it has fields.
+
+                    var type = GetTypeFromDefinition(reader, typeDefHandle);
+
+                    if (typeDef.GetFields().Count > 0)
+                    {
+                        var err = $"Explicit layout type {type} may not have fields.";
+                        errors.Add(new SandboxError(err));
+                    }
+                }
+            }
+        }
+
         private void CheckMemberReferences(
             SandboxConfig sandboxConfig,
             List<MMemberRef> members,
@@ -746,7 +771,7 @@ namespace Robust.Shared.ContentPack
         /// <exception href="UnsupportedMetadataException">
         ///     Thrown if the metadata does something funny we don't "support" like type forwarding.
         /// </exception>
-        private static MTypeReferenced ParseTypeReference(MetadataReader reader, TypeReferenceHandle handle)
+        internal static MTypeReferenced ParseTypeReference(MetadataReader reader, TypeReferenceHandle handle)
         {
             var typeRef = reader.GetTypeReference(handle);
             var name = reader.GetString(typeRef.Name);
@@ -883,7 +908,7 @@ namespace Robust.Shared.ContentPack
             }
         }
 
-        private sealed class TypeProvider : ISignatureTypeProvider<MType, int>
+        internal sealed class TypeProvider : ISignatureTypeProvider<MType, int>
         {
             public MType GetSZArrayType(MType elementType)
             {

Robust.Shared/ContentPack/ModLoader.cs

@@ -90,7 +90,11 @@ namespace Robust.Shared.ContentPack
                 Logger.DebugS("res.mod", $"Found module '{fullPath}'");
 
                 using var asmFile = _res.ContentFileRead(fullPath);
-                var (asmRefs, asmName) = GetAssemblyReferenceData(asmFile);
+                var refData = GetAssemblyReferenceData(asmFile);
+                if (refData == null)
+                    continue;
+
+                var (asmRefs, asmName) = refData.Value;
 
                 if (!files.TryAdd(asmName, (fullPath, asmRefs)))
                 {
@@ -158,18 +162,48 @@ namespace Robust.Shared.ContentPack
             return true;
         }
 
-        private static (string[] refs, string name) GetAssemblyReferenceData(Stream stream)
+        private (string[] refs, string name)? GetAssemblyReferenceData(Stream stream)
         {
             using var reader = ModLoader.MakePEReader(stream);
             var metaReader = reader.GetMetadataReader();
 
             var name = metaReader.GetString(metaReader.GetAssemblyDefinition().Name);
 
+            // Try to find SkipIfSandboxedAttribute.
+
+            if (_sandboxingEnabled && TryFindSkipIfSandboxed(metaReader))
+            {
+                Logger.DebugS("res.mod", "Module {ModuleName} has SkipIfSandboxedAttribute, ignoring.", name);
+                return null;
+            }
+
             return (metaReader.AssemblyReferences
                 .Select(a => metaReader.GetAssemblyReference(a))
                 .Select(a => metaReader.GetString(a.Name)).ToArray(), name);
         }
 
+        private static bool TryFindSkipIfSandboxed(MetadataReader reader)
+        {
+            foreach (var attribHandle in reader.CustomAttributes)
+            {
+                var attrib = reader.GetCustomAttribute(attribHandle);
+                if (attrib.Parent.Kind != HandleKind.AssemblyDefinition)
+                    continue;
+
+                var ctor = attrib.Constructor;
+                if (ctor.Kind != HandleKind.MemberReference)
+                    continue;
+
+                var memberRef = reader.GetMemberReference((MemberReferenceHandle) ctor);
+                var typeRef = AssemblyTypeChecker.ParseTypeReference(reader, (TypeReferenceHandle)memberRef.Parent);
+
+                if (typeRef.Namespace == "Robust.Shared.ContentPack" && typeRef.Name == "SkipIfSandboxedAttribute")
+                    return true;
+            }
+
+            return false;
+        }
+
         public void LoadGameAssembly(Stream assembly, Stream? symbols = null, bool skipVerify = false)
         {
             if (!skipVerify && !MakeTypeChecker().CheckAssembly(assembly))
@@ -329,7 +363,7 @@ namespace Robust.Shared.ContentPack
         public void Dispose()
         {
             _loadContext.Unload();
-            AssemblyLoadContext.Default.Resolving += DefaultOnResolving;
+            AssemblyLoadContext.Default.Resolving -= DefaultOnResolving;
         }
 
         private Assembly? DefaultOnResolving(AssemblyLoadContext ctx, AssemblyName name)