WIP

.dockerignore

@@ -0,0 +1,9 @@
+# Ignore hidden files
+.*
+
+# Include .git for build version information
+!.git
+
+# Not needed for building
+AddMigration.*
+*.DotSettings.user

.run/Agent 1.run.xml

@@ -5,13 +5,13 @@
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/.workdir/Agent1" />
     <option name="PASS_PARENT_ENVS" value="1" />
     <envs>
+      <env name="AGENT_KEY" value="JXBQQYG5T267RQS75MXWBTCJZY5CKTCCGQY22MCZPHSQQSJYCHH2NG2TCNXQY6TBSXM9NQDRS2CMX" />
       <env name="AGENT_NAME" value="Agent 1" />
       <env name="ALLOWED_RCON_PORTS" value="25575,27000,27001" />
       <env name="ALLOWED_SERVER_PORTS" value="25565,26000,26001" />
       <env name="JAVA_SEARCH_PATH" value="~/.jdks" />
       <env name="MAX_INSTANCES" value="3" />
       <env name="MAX_MEMORY" value="12G" />
-      <env name="SERVER_AUTH_TOKEN_FILE" value="./secrets/agent.token" />
       <env name="SERVER_HOST" value="localhost" />
     </envs>
     <option name="USE_EXTERNAL_CONSOLE" value="0" />

.run/Agent 2.run.xml

@@ -5,13 +5,13 @@
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/.workdir/Agent2" />
     <option name="PASS_PARENT_ENVS" value="1" />
     <envs>
+      <env name="AGENT_KEY" value="JXBQQYG5T267RQS75MXWBTCJZY5CKTCCGQY22MCZPHSQQSJYCHH2NG2TCNXQY6TBSXM9NQDRS2CMX" />
       <env name="AGENT_NAME" value="Agent 2" />
       <env name="ALLOWED_RCON_PORTS" value="27002-27006" />
       <env name="ALLOWED_SERVER_PORTS" value="26002-26006" />
       <env name="JAVA_SEARCH_PATH" value="~/.jdks" />
       <env name="MAX_INSTANCES" value="5" />
       <env name="MAX_MEMORY" value="10G" />
-      <env name="SERVER_AUTH_TOKEN_FILE" value="./secrets/agent.token" />
       <env name="SERVER_HOST" value="localhost" />
     </envs>
     <option name="USE_EXTERNAL_CONSOLE" value="0" />

.run/Agent 3.run.xml

@@ -5,13 +5,13 @@
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/.workdir/Agent3" />
     <option name="PASS_PARENT_ENVS" value="1" />
     <envs>
+      <env name="AGENT_KEY" value="JXBQQYG5T267RQS75MXWBTCJZY5CKTCCGQY22MCZPHSQQSJYCHH2NG2TCNXQY6TBSXM9NQDRS2CMX" />
       <env name="AGENT_NAME" value="Agent 3" />
       <env name="ALLOWED_RCON_PORTS" value="27007" />
       <env name="ALLOWED_SERVER_PORTS" value="26007" />
       <env name="JAVA_SEARCH_PATH" value="~/.jdks" />
       <env name="MAX_INSTANCES" value="1" />
       <env name="MAX_MEMORY" value="2560M" />
-      <env name="SERVER_AUTH_TOKEN_FILE" value="./secrets/agent.token" />
       <env name="SERVER_HOST" value="localhost" />
     </envs>
     <option name="USE_EXTERNAL_CONSOLE" value="0" />

.workdir/.gitignore

@@ -1,2 +0,0 @@
-/Agent*/data
-/Agent*/temp

.workdir/Agent1/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

.workdir/Agent1/secrets/agent.key

@@ -1 +0,0 @@
-tLkn<EFBFBD>Z<EFBFBD><EFBFBD>}ы<><D18B>|~2<><32>><3E><>р<EFBFBD><D180>O*<2A>	p

.workdir/Agent1/secrets/agent.token

@@ -1 +0,0 @@
-TH7Z2MJKMR975N6HFBKQP9WQFMWWN5

.workdir/Agent2/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

.workdir/Agent2/secrets/agent.key

@@ -1 +0,0 @@
-tLkn<EFBFBD>Z<EFBFBD><EFBFBD>}ы<><D18B>|~2<><32>><3E><>р<EFBFBD><D180>O*<2A>	p

.workdir/Agent2/secrets/agent.token

@@ -1 +0,0 @@
-TH7Z2MJKMR975N6HFBKQP9WQFMWWN5

.workdir/Agent3/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

.workdir/Agent3/secrets/agent.key

@@ -1 +0,0 @@
-tLkn<EFBFBD>Z<EFBFBD><EFBFBD>}ы<><D18B>|~2<><32>><3E><>р<EFBFBD><D180>O*<2A>	p

.workdir/Agent3/secrets/agent.token

@@ -1 +0,0 @@
-TH7Z2MJKMR975N6HFBKQP9WQFMWWN5

.workdir/Server/.gitignore

@@ -0,0 +1 @@
+/keys

.workdir/Server/secrets/agent.token

@@ -1 +0,0 @@
-TH7Z2MJKMR975N6HFBKQP9WQFMWWN5

.workdir/Server/secrets/secret.key

@@ -1 +1 @@
-+<2B><><EFBFBD><EFBFBD><<3C>f:<3A>bJ"e<18>׸ބ<D7B8><1F><><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>
+<EFBFBD>Z<EFBFBD>t<>MPI<49>GMZ<4D><5A><EFBFBD><EFBFBD>kN<6B>VF1X<EFBFBD><EFBFBD>p

Agent/Phantom.Agent.Minecraft/Command/MinecraftCommand.cs

@@ -0,0 +1,15 @@
+namespace Phantom.Agent.Minecraft.Command; 
+
+public static class MinecraftCommand {
+	public const string SaveOn = "save-on";
+	public const string SaveOff = "save-off";
+	public const string Stop = "stop";
+	
+	public static string Say(string message) {
+		return "say " + message;
+	}
+
+	public static string SaveAll(bool flush) {
+		return flush ? "save-all flush" : "save-all";
+	}
+}

Agent/Phantom.Agent.Minecraft/Instance/InstanceProcess.cs

@@ -1,23 +1,25 @@
-using System.Diagnostics;
-using Phantom.Utils.Collections;
+using Phantom.Utils.Collections;
+using Phantom.Utils.Runtime;
 
 namespace Phantom.Agent.Minecraft.Instance; 
 
-public sealed class InstanceSession : IDisposable {
+public sealed class InstanceProcess : IDisposable {
+	public InstanceProperties InstanceProperties { get; }
+	public CancellableSemaphore BackupSemaphore { get; } = new (1, 1);
+	
 	private readonly RingBuffer<string> outputBuffer = new (10000);
 	private event EventHandler<string>? OutputEvent;
 
-	public event EventHandler? SessionEnded;
+	public event EventHandler? Ended;
 	public bool HasEnded { get; private set; }
 
 	private readonly Process process;
 
-	internal InstanceSession(Process process) {
+	internal InstanceProcess(InstanceProperties instanceProperties, Process process) {
+		this.InstanceProperties = instanceProperties;
 		this.process = process;
-		this.process.EnableRaisingEvents = true;
 		this.process.Exited += ProcessOnExited;
-		this.process.OutputDataReceived += HandleOutputLine;
-		this.process.ErrorDataReceived += HandleOutputLine;
+		this.process.OutputReceived += ProcessOutputReceived;
 	}
 
 	public async Task SendCommand(string command, CancellationToken cancellationToken) {
@@ -36,17 +38,15 @@ public sealed class InstanceSession : IDisposable {
 		OutputEvent -= listener;
 	}
 
-	private void HandleOutputLine(object sender, DataReceivedEventArgs args) {
-		if (args.Data is {} line) {
-			outputBuffer.Add(line);
-			OutputEvent?.Invoke(this, line);
-		}
+	private void ProcessOutputReceived(object? sender, Process.Output output) {
+		outputBuffer.Add(output.Line);
+		OutputEvent?.Invoke(this, output.Line);
 	}
 
 	private void ProcessOnExited(object? sender, EventArgs e) {
 		OutputEvent = null;
 		HasEnded = true;
-		SessionEnded?.Invoke(this, EventArgs.Empty);
+		Ended?.Invoke(this, EventArgs.Empty);
 	}
 
 	public void Kill() {
@@ -61,7 +61,8 @@ public sealed class InstanceSession : IDisposable {
 
 	public void Dispose() {
 		process.Dispose();
+		BackupSemaphore.Dispose();
 		OutputEvent = null;
-		SessionEnded = null;
+		Ended = null;
 	}
 }

Agent/Phantom.Agent.Minecraft/Instance/InstanceProperties.cs

@@ -1,12 +1,17 @@
-using Phantom.Agent.Minecraft.Java;
+using System.Collections.Immutable;
+using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Properties;
+using Phantom.Common.Data.Instance;
 
 namespace Phantom.Agent.Minecraft.Instance;
 
 public sealed record InstanceProperties(
+	Guid InstanceGuid,
 	Guid JavaRuntimeGuid,
 	JvmProperties JvmProperties,
+	ImmutableArray<string> JvmArguments,
 	string InstanceFolder,
 	string ServerVersion,
-	ServerProperties ServerProperties
+	ServerProperties ServerProperties,
+	InstanceLaunchProperties LaunchProperties
 );

Agent/Phantom.Agent.Minecraft/Java/JavaRuntimeDiscovery.cs

@@ -7,7 +7,7 @@ using Serilog;
 namespace Phantom.Agent.Minecraft.Java;
 
 public sealed class JavaRuntimeDiscovery {
-	private static readonly ILogger Logger = PhantomLogger.Create(typeof(JavaRuntimeDiscovery));
+	private static readonly ILogger Logger = PhantomLogger.Create(nameof(JavaRuntimeDiscovery));
 
 	public static string? GetSystemSearchPath() {
 		const string LinuxJavaPath = "/usr/lib/jvm";
@@ -38,28 +38,38 @@ public sealed class JavaRuntimeDiscovery {
 			AttributesToSkip = FileAttributes.Hidden | FileAttributes.ReparsePoint | FileAttributes.System
 		}).Order()) {
 			var javaExecutablePath = Paths.NormalizeSlashes(Path.Combine(binFolderPath, javaExecutableName));
-			if (File.Exists(javaExecutablePath)) {
-				Logger.Information("Found candidate Java executable: {JavaExecutablePath}", javaExecutablePath);
 			
-				JavaRuntime? foundRuntime;
-				try {
-					foundRuntime = await TryReadJavaRuntimeInformationFromProcess(javaExecutablePath);
-				} catch (OperationCanceledException) {
-					Logger.Error("Java process did not exit in time.");
-					continue;
-				} catch (Exception e) {
-					Logger.Error(e, "Caught exception while reading Java version information.");
-					continue;
-				}
-
-				if (foundRuntime == null) {
-					Logger.Error("Java executable did not output version information.");
-					continue;
-				}
-
-				Logger.Information("Found Java {DisplayName} at: {Path}", foundRuntime.DisplayName, javaExecutablePath);
-				yield return new JavaRuntimeExecutable(javaExecutablePath, foundRuntime);
+			FileAttributes javaExecutableAttributes;
+			try {
+				javaExecutableAttributes = File.GetAttributes(javaExecutablePath);
+			} catch (Exception) {
+				continue;
 			}
+
+			if (javaExecutableAttributes.HasFlag(FileAttributes.ReparsePoint)) {
+				continue;
+			}
+
+			Logger.Information("Found candidate Java executable: {JavaExecutablePath}", javaExecutablePath);
+
+			JavaRuntime? foundRuntime;
+			try {
+				foundRuntime = await TryReadJavaRuntimeInformationFromProcess(javaExecutablePath);
+			} catch (OperationCanceledException) {
+				Logger.Error("Java process did not exit in time.");
+				continue;
+			} catch (Exception e) {
+				Logger.Error(e, "Caught exception while reading Java version information.");
+				continue;
+			}
+
+			if (foundRuntime == null) {
+				Logger.Error("Java executable did not output version information.");
+				continue;
+			}
+
+			Logger.Information("Found Java {DisplayName} at: {Path}", foundRuntime.DisplayName, javaExecutablePath);
+			yield return new JavaRuntimeExecutable(javaExecutablePath, foundRuntime);
 		}
 	}
 

Agent/Phantom.Agent.Minecraft/Java/JvmArgumentBuilder.cs

@@ -1,25 +1,31 @@
-using System.Collections.ObjectModel;
+using System.Collections.Immutable;
+using System.Collections.ObjectModel;
 
 namespace Phantom.Agent.Minecraft.Java;
 
 sealed class JvmArgumentBuilder {
 	private readonly JvmProperties basicProperties;
-	private readonly List<string> customProperties = new ();
+	private readonly List<string> customArguments = new ();
 
-	public JvmArgumentBuilder(JvmProperties basicProperties) {
+	public JvmArgumentBuilder(JvmProperties basicProperties, ImmutableArray<string> customArguments) {
 		this.basicProperties = basicProperties;
+
+		foreach (var jvmArgument in customArguments) {
+			this.customArguments.Add(jvmArgument);
+		}
 	}
 
 	public void AddProperty(string key, string value) {
-		customProperties.Add("-D" + key + "=\"" + value + "\""); // TODO test quoting?
+		customArguments.Add("-D" + key + "=\"" + value + "\""); // TODO test quoting?
 	}
 
 	public void Build(Collection<string> target) {
-		target.Add("-Xms" + basicProperties.InitialHeapMegabytes + "M");
-		target.Add("-Xmx" + basicProperties.MaximumHeapMegabytes + "M");
-
-		foreach (var property in customProperties) {
+		foreach (var property in customArguments) {
 			target.Add(property);
 		}
+
+		target.Add("-Xms" + basicProperties.InitialHeapMegabytes + "M");
+		target.Add("-Xmx" + basicProperties.MaximumHeapMegabytes + "M");
+		target.Add("-Xrs");
 	}
 }

Agent/Phantom.Agent.Minecraft/Launcher/BaseLauncher.cs

@@ -1,66 +1,105 @@
-using System.Diagnostics;
-using System.Text;
+using System.Text;
 using Kajabity.Tools.Java;
 using Phantom.Agent.Minecraft.Instance;
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Server;
+using Phantom.Common.Minecraft;
+using Phantom.Utils.Runtime;
+using Serilog;
 
 namespace Phantom.Agent.Minecraft.Launcher;
 
-public abstract class BaseLauncher {
+public abstract class BaseLauncher : IServerLauncher {
 	private readonly InstanceProperties instanceProperties;
 
+	protected string MinecraftVersion => instanceProperties.ServerVersion;
+
 	private protected BaseLauncher(InstanceProperties instanceProperties) {
 		this.instanceProperties = instanceProperties;
 	}
 
-	public async Task<LaunchResult> Launch(LaunchServices services, EventHandler<DownloadProgressEventArgs> downloadProgressEventHandler, CancellationToken cancellationToken) {
+	public async Task<LaunchResult> Launch(ILogger logger, LaunchServices services, EventHandler<DownloadProgressEventArgs> downloadProgressEventHandler, CancellationToken cancellationToken) {
 		if (!services.JavaRuntimeRepository.TryGetByGuid(instanceProperties.JavaRuntimeGuid, out var javaRuntimeExecutable)) {
 			return new LaunchResult.InvalidJavaRuntime();
 		}
 
-		var vanillaServerJarPath = await services.ServerExecutables.DownloadAndGetPath(instanceProperties.ServerVersion, downloadProgressEventHandler, cancellationToken);
+		if (JvmArgumentsHelper.Validate(instanceProperties.JvmArguments) != null) {
+			return new LaunchResult.InvalidJvmArguments();
+		}
+
+		var vanillaServerJarPath = await services.ServerExecutables.DownloadAndGetPath(instanceProperties.LaunchProperties.ServerDownloadInfo, MinecraftVersion, downloadProgressEventHandler, cancellationToken);
 		if (vanillaServerJarPath == null) {
 			return new LaunchResult.CouldNotDownloadMinecraftServer();
 		}
 
-		var startInfo = new ProcessStartInfo {
+		ServerJarInfo? serverJar;
+		try {
+			serverJar = await PrepareServerJar(logger, vanillaServerJarPath, cancellationToken);
+		} catch (OperationCanceledException) {
+			throw;
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while preparing the server jar.");
+			return new LaunchResult.CouldNotPrepareMinecraftServerLauncher();
+		}
+
+		if (!File.Exists(serverJar.FilePath)) {
+			logger.Error("Missing prepared server or launcher jar: {FilePath}", serverJar.FilePath);
+			return new LaunchResult.CouldNotPrepareMinecraftServerLauncher();
+		}
+
+		try {
+			await AcceptEula(instanceProperties);
+			await UpdateServerProperties(instanceProperties);
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while configuring the server.");
+			return new LaunchResult.CouldNotConfigureMinecraftServer();
+		}
+		
+		var processConfigurator = new ProcessConfigurator {
 			FileName = javaRuntimeExecutable.ExecutablePath,
 			WorkingDirectory = instanceProperties.InstanceFolder,
-			RedirectStandardInput = true,
-			RedirectStandardOutput = true,
-			RedirectStandardError = true,
-			UseShellExecute = false,
-			CreateNoWindow = false
+			RedirectInput = true,
+			UseShellExecute = false
 		};
 		
-		var jvmArguments = new JvmArgumentBuilder(instanceProperties.JvmProperties);
+		var jvmArguments = new JvmArgumentBuilder(instanceProperties.JvmProperties, instanceProperties.JvmArguments);
 		CustomizeJvmArguments(jvmArguments);
 
-		var serverJarPath = await PrepareServerJar(vanillaServerJarPath, instanceProperties.InstanceFolder, cancellationToken);
-		var processArguments = startInfo.ArgumentList;
+		var processArguments = processConfigurator.ArgumentList;
 		jvmArguments.Build(processArguments);
+		
+		foreach (var extraArgument in serverJar.ExtraArgs) {
+			processArguments.Add(extraArgument);
+		}
+		
 		processArguments.Add("-jar");
-		processArguments.Add(serverJarPath);
+		processArguments.Add(serverJar.FilePath);
 		processArguments.Add("nogui");
 
-		var process = new Process { StartInfo = startInfo };
-		var session = new InstanceSession(process);
+		var process = processConfigurator.CreateProcess();
+		var instanceProcess = new InstanceProcess(instanceProperties, process);
 
-		await AcceptEula(instanceProperties);
-		await UpdateServerProperties(instanceProperties);
+		try {
+			process.Start();
+		} catch (Exception launchException) {
+			logger.Error(launchException, "Caught exception launching the server process.");
 			
-		process.Start();
-		process.BeginOutputReadLine();
-		process.BeginErrorReadLine();
+			try {
+				process.Kill();
+			} catch (Exception killException) {
+				logger.Error(killException, "Caught exception trying to kill the server process after a failed launch.");
+			}
 
-		return new LaunchResult.Success(session);
+			return new LaunchResult.CouldNotStartMinecraftServer();
+		}
+
+		return new LaunchResult.Success(instanceProcess);
 	}
 
 	private protected virtual void CustomizeJvmArguments(JvmArgumentBuilder arguments) {}
 
-	private protected virtual Task<string> PrepareServerJar(string serverJarPath, string instanceFolderPath, CancellationToken cancellationToken) {
-		return Task.FromResult(serverJarPath);
+	private protected virtual Task<ServerJarInfo> PrepareServerJar(ILogger logger, string serverJarPath, CancellationToken cancellationToken) {
+		return Task.FromResult(new ServerJarInfo(serverJarPath));
 	}
 
 	private static async Task AcceptEula(InstanceProperties instanceProperties) {
@@ -72,16 +111,18 @@ public abstract class BaseLauncher {
 		var serverPropertiesFilePath = Path.Combine(instanceProperties.InstanceFolder, "server.properties");
 		var serverPropertiesData = new JavaProperties();
 
+		await using var fileStream = new FileStream(serverPropertiesFilePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
 		try {
-			await using var readStream = new FileStream(serverPropertiesFilePath, FileMode.Open, FileAccess.Read, FileShare.Read);
-			serverPropertiesData.Load(readStream);
-		} catch (FileNotFoundException) {
-			// ignore
+			serverPropertiesData.Load(fileStream);
+		} catch (ParseException e) {
+			throw new Exception("Could not parse server.properties file: " + serverPropertiesFilePath, e);
 		}
 		
 		instanceProperties.ServerProperties.SetTo(serverPropertiesData);
 
-		await using var writeStream = new FileStream(serverPropertiesFilePath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None);
-		serverPropertiesData.Store(writeStream, true);
+		fileStream.Seek(0L, SeekOrigin.Begin);
+		fileStream.SetLength(0L);
+		
+		serverPropertiesData.Store(fileStream, true);
 	}
 }

Agent/Phantom.Agent.Minecraft/Launcher/IServerLauncher.cs

@@ -0,0 +1,8 @@
+using Phantom.Agent.Minecraft.Server;
+using Serilog;
+
+namespace Phantom.Agent.Minecraft.Launcher;
+
+public interface IServerLauncher {
+	Task<LaunchResult> Launch(ILogger logger, LaunchServices services, EventHandler<DownloadProgressEventArgs> downloadProgressEventHandler, CancellationToken cancellationToken);
+}

Agent/Phantom.Agent.Minecraft/Launcher/LaunchResult.cs

@@ -5,9 +5,17 @@ namespace Phantom.Agent.Minecraft.Launcher;
 public abstract record LaunchResult {
 	private LaunchResult() {}
 
-	public sealed record Success(InstanceSession Session) : LaunchResult;
+	public sealed record Success(InstanceProcess Process) : LaunchResult;
 
 	public sealed record InvalidJavaRuntime : LaunchResult;
 	
+	public sealed record InvalidJvmArguments : LaunchResult;
+
 	public sealed record CouldNotDownloadMinecraftServer : LaunchResult;
+	
+	public sealed record CouldNotPrepareMinecraftServerLauncher : LaunchResult;
+	
+	public sealed record CouldNotConfigureMinecraftServer : LaunchResult;
+	
+	public sealed record CouldNotStartMinecraftServer : LaunchResult;
 }

Agent/Phantom.Agent.Minecraft/Launcher/ServerJarInfo.cs

@@ -0,0 +1,7 @@
+using System.Collections.Immutable;
+
+namespace Phantom.Agent.Minecraft.Launcher;
+
+sealed record ServerJarInfo(string FilePath, ImmutableArray<string> ExtraArgs) {
+	public ServerJarInfo(string filePath) : this(filePath, ImmutableArray<string>.Empty) {}
+}

Agent/Phantom.Agent.Minecraft/Launcher/Types/FabricLauncher.cs

@@ -0,0 +1,55 @@
+using System.Collections.Immutable;
+using Phantom.Agent.Minecraft.Instance;
+using Phantom.Utils.IO;
+using Serilog;
+
+namespace Phantom.Agent.Minecraft.Launcher.Types; 
+
+public sealed class FabricLauncher : BaseLauncher {
+	public FabricLauncher(InstanceProperties instanceProperties) : base(instanceProperties) {}
+	
+	private protected override async Task<ServerJarInfo> PrepareServerJar(ILogger logger, string serverJarPath, CancellationToken cancellationToken) {
+		var serverJarParentFolderPath = Directory.GetParent(serverJarPath);
+		if (serverJarParentFolderPath == null) {
+			throw new ArgumentException("Could not get parent folder from: " + serverJarPath, nameof(serverJarPath));
+		}
+		
+		var launcherJarPath = Path.Combine(serverJarParentFolderPath.FullName, "fabric.jar");
+		
+		if (!File.Exists(launcherJarPath)) {
+			await DownloadLauncher(logger, launcherJarPath, cancellationToken);
+		}
+
+		return new ServerJarInfo(launcherJarPath, ImmutableArray.Create("-Dfabric.installer.server.gameJar=" + Paths.NormalizeSlashes(serverJarPath)));
+	}
+
+	private async Task DownloadLauncher(ILogger logger, string targetFilePath, CancellationToken cancellationToken) {
+		// TODO customizable loader version, probably with a dedicated temporary folder
+		string installerUrl = $"https://meta.fabricmc.net/v2/versions/loader/{MinecraftVersion}/stable/stable/server/jar";
+		logger.Information("Downloading Fabric launcher from: {Url}", installerUrl);
+		
+		using var http = new HttpClient();
+		
+		var response = await http.GetAsync(installerUrl, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
+		response.EnsureSuccessStatusCode();
+		
+		try {
+			await using var fileStream = new FileStream(targetFilePath, FileMode.CreateNew, FileAccess.Write, FileShare.Read);
+			await using var responseStream = await response.Content.ReadAsStreamAsync(cancellationToken);
+			await responseStream.CopyToAsync(fileStream, cancellationToken);
+		} catch (Exception) {
+			TryDeleteLauncherAfterFailure(logger, targetFilePath);
+			throw;
+		}
+	}
+
+	private static void TryDeleteLauncherAfterFailure(ILogger logger, string filePath) {
+		if (File.Exists(filePath)) {
+			try {
+				File.Delete(filePath);
+			} catch (Exception e) {
+				logger.Warning(e, "Could not clean up partially downloaded Fabric launcher: {FilePath}", filePath);
+			}
+		}
+	}
+}

Agent/Phantom.Agent.Minecraft/Launcher/Types/ForgeLauncher.cs

@@ -0,0 +1,12 @@
+using Phantom.Agent.Minecraft.Instance;
+using Phantom.Agent.Minecraft.Java;
+
+namespace Phantom.Agent.Minecraft.Launcher.Types; 
+
+public class ForgeLauncher : BaseLauncher {
+	public ForgeLauncher(InstanceProperties instanceProperties) : base(instanceProperties) {}
+	
+	private protected override void CustomizeJvmArguments(JvmArgumentBuilder arguments) {
+		arguments.AddProperty("terminal.ansi", "true"); // TODO
+	}
+}

Agent/Phantom.Agent.Minecraft/Launcher/Types/InvalidLauncher.cs

@@ -0,0 +1,14 @@
+using Phantom.Agent.Minecraft.Server;
+using Serilog;
+
+namespace Phantom.Agent.Minecraft.Launcher.Types; 
+
+public sealed class InvalidLauncher : IServerLauncher {
+	public static InvalidLauncher Instance { get; } = new ();
+	
+	private InvalidLauncher() {}
+	
+	public Task<LaunchResult> Launch(ILogger logger, LaunchServices services, EventHandler<DownloadProgressEventArgs> downloadProgressEventHandler, CancellationToken cancellationToken) {
+		return Task.FromResult<LaunchResult>(new LaunchResult.CouldNotPrepareMinecraftServerLauncher());
+	}
+}

Agent/Phantom.Agent.Minecraft/Phantom.Agent.Minecraft.csproj

@@ -7,15 +7,17 @@
   </PropertyGroup>
   
   <ItemGroup>
-    <PackageReference Include="Kajabity.Tools.Java" Version="0.3.7879.40798" />
+    <PackageReference Include="Kajabity.Tools.Java" />
   </ItemGroup>
   
   <ItemGroup>
     <ProjectReference Include="..\..\Common\Phantom.Common.Data\Phantom.Common.Data.csproj" />
     <ProjectReference Include="..\..\Common\Phantom.Common.Logging\Phantom.Common.Logging.csproj" />
+    <ProjectReference Include="..\..\Common\Phantom.Common.Minecraft\Phantom.Common.Minecraft.csproj" />
     <ProjectReference Include="..\..\Utils\Phantom.Utils.Collections\Phantom.Utils.Collections.csproj" />
     <ProjectReference Include="..\..\Utils\Phantom.Utils.Cryptography\Phantom.Utils.Cryptography.csproj" />
     <ProjectReference Include="..\..\Utils\Phantom.Utils.IO\Phantom.Utils.IO.csproj" />
+    <ProjectReference Include="..\..\Utils\Phantom.Utils.Runtime\Phantom.Utils.Runtime.csproj" />
   </ItemGroup>
 
 </Project>

Agent/Phantom.Agent.Minecraft/Server/MinecraftServerExecutableDownloader.cs

@@ -1,9 +1,9 @@
-using System.Net.Http.Json;
-using System.Security.Cryptography;
-using System.Text.Json;
+using System.Security.Cryptography;
+using Phantom.Common.Data.Minecraft;
 using Phantom.Common.Logging;
 using Phantom.Utils.Cryptography;
 using Phantom.Utils.IO;
+using Phantom.Utils.Runtime;
 using Serilog;
 
 namespace Phantom.Agent.Minecraft.Server;
@@ -11,8 +11,6 @@ namespace Phantom.Agent.Minecraft.Server;
 sealed class MinecraftServerExecutableDownloader {
 	private static readonly ILogger Logger = PhantomLogger.Create<MinecraftServerExecutableDownloader>();
 
-	private const string VersionManifestUrl = "https://launchermeta.mojang.com/mc/game/version_manifest.json";
-
 	public Task<string?> Task { get; }
 	public event EventHandler<DownloadProgressEventArgs>? DownloadProgress;
 	public event EventHandler? Completed;
@@ -20,15 +18,15 @@ sealed class MinecraftServerExecutableDownloader {
 	private readonly CancellationTokenSource cancellationTokenSource = new ();
 	private int listeners = 0;
 
-	public MinecraftServerExecutableDownloader(string version, string filePath, MinecraftServerExecutableDownloadListener listener) {
+	public MinecraftServerExecutableDownloader(FileDownloadInfo fileDownloadInfo, string minecraftVersion, string filePath, MinecraftServerExecutableDownloadListener listener) {
 		Register(listener);
-		Task = DownloadAndGetPath(version, filePath);
+		Task = DownloadAndGetPath(fileDownloadInfo, minecraftVersion, filePath);
 		Task.ContinueWith(OnCompleted, TaskScheduler.Default);
 	}
 
 	public void Register(MinecraftServerExecutableDownloadListener listener) {
 		++listeners;
-		Logger.Verbose("Registered download listener, current listener count: {Listeners}", listeners);
+		Logger.Debug("Registered download listener, current listener count: {Listeners}", listeners);
 		
 		DownloadProgress += listener.DownloadProgressEventHandler;
 		listener.CancellationToken.Register(Unregister, listener);
@@ -39,11 +37,11 @@ sealed class MinecraftServerExecutableDownloader {
 		DownloadProgress -= listener.DownloadProgressEventHandler;
 
 		if (--listeners <= 0) {
-			Logger.Verbose("Unregistered last download listener, cancelling download.");
+			Logger.Debug("Unregistered last download listener, cancelling download.");
 			cancellationTokenSource.Cancel();
 		}
 		else {
-			Logger.Verbose("Unregistered download listener, current listener count: {Listeners}", listeners);
+			Logger.Debug("Unregistered download listener, current listener count: {Listeners}", listeners);
 		}
 	}
 
@@ -52,7 +50,7 @@ sealed class MinecraftServerExecutableDownloader {
 	}
 
 	private void OnCompleted(Task task) {
-		Logger.Verbose("Download task completed.");
+		Logger.Debug("Download task completed.");
 		Completed?.Invoke(this, EventArgs.Empty);
 		Completed = null;
 		DownloadProgress = null;
@@ -70,36 +68,26 @@ sealed class MinecraftServerExecutableDownloader {
 		}
 	}
 
-	private async Task<string?> DownloadAndGetPath(string version, string filePath) {
-		Logger.Information("Downloading server version {Version}...", version);
-
-		HttpClient http = new HttpClient();
+	private async Task<string?> DownloadAndGetPath(FileDownloadInfo fileDownloadInfo, string minecraftVersion, string filePath) {
 		string tmpFilePath = filePath + ".tmp";
 
 		var cancellationToken = cancellationTokenSource.Token;
 		try {
-			Logger.Information("Fetching version manifest from: {Url}", VersionManifestUrl);
-			var versionManifest = await FetchVersionManifest(http, cancellationToken);
-			var metadataUrl = GetVersionMetadataUrlFromManifest(version, versionManifest);
-
-			Logger.Information("Fetching metadata for version {Version} from: {Url}", version, metadataUrl);
-			var versionMetadata = await FetchVersionMetadata(http, metadataUrl, cancellationToken);
-			var serverExecutableInfo = GetServerExecutableUrlFromMetadata(versionMetadata);
-
-			Logger.Information("Downloading server executable from: {Url} ({Size})", serverExecutableInfo.DownloadUrl, serverExecutableInfo.Size.ToHumanReadable(decimalPlaces: 1));
+			Logger.Information("Downloading server version {Version} from: {Url} ({Size})", minecraftVersion, fileDownloadInfo.DownloadUrl, fileDownloadInfo.Size.ToHumanReadable(decimalPlaces: 1));
 			try {
-				await FetchServerExecutableFile(http, new DownloadProgressCallback(this), serverExecutableInfo, tmpFilePath, cancellationToken);
+				using var http = new HttpClient();
+				await FetchServerExecutableFile(http, new DownloadProgressCallback(this), fileDownloadInfo, tmpFilePath, cancellationToken);
 			} catch (Exception) {
 				TryDeleteExecutableAfterFailure(tmpFilePath);
 				throw;
 			}
 
 			File.Move(tmpFilePath, filePath, true);
-			Logger.Information("Server version {Version} downloaded.", version);
+			Logger.Information("Server version {Version} downloaded.", minecraftVersion);
 
 			return filePath;
 		} catch (OperationCanceledException) {
-			Logger.Information("Download for server version {Version} was cancelled.", version);
+			Logger.Information("Download for server version {Version} was cancelled.", minecraftVersion);
 			throw;
 		} catch (StopProcedureException) {
 			return null;
@@ -111,41 +99,17 @@ sealed class MinecraftServerExecutableDownloader {
 		}
 	}
 
-	private static async Task<JsonElement> FetchVersionManifest(HttpClient http, CancellationToken cancellationToken) {
-		try {
-			return await http.GetFromJsonAsync<JsonElement>(VersionManifestUrl, cancellationToken);
-		} catch (HttpRequestException e) {
-			Logger.Error(e, "Unable to download version manifest.");
-			throw StopProcedureException.Instance;
-		} catch (Exception e) {
-			Logger.Error(e, "Unable to parse version manifest as JSON.");
-			throw StopProcedureException.Instance;
-		}
-	}
-
-	private static async Task<JsonElement> FetchVersionMetadata(HttpClient http, string metadataUrl, CancellationToken cancellationToken) {
-		try {
-			return await http.GetFromJsonAsync<JsonElement>(metadataUrl, cancellationToken);
-		} catch (HttpRequestException e) {
-			Logger.Error(e, "Unable to download version metadata.");
-			throw StopProcedureException.Instance;
-		} catch (Exception e) {
-			Logger.Error(e, "Unable to parse version metadata as JSON.");
-			throw StopProcedureException.Instance;
-		}
-	}
-
-	private static async Task FetchServerExecutableFile(HttpClient http, DownloadProgressCallback progressCallback, ServerExecutableInfo info, string filePath, CancellationToken cancellationToken) {
+	private static async Task FetchServerExecutableFile(HttpClient http, DownloadProgressCallback progressCallback, FileDownloadInfo fileDownloadInfo, string filePath, CancellationToken cancellationToken) {
 		Sha1String downloadedFileHash;
 
 		try {
-			var response = await http.GetAsync(info.DownloadUrl, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
+			var response = await http.GetAsync(fileDownloadInfo.DownloadUrl, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
 			response.EnsureSuccessStatusCode();
 
 			await using var fileStream = new FileStream(filePath, FileMode.CreateNew, FileAccess.Write, FileShare.Read);
 			await using var responseStream = await response.Content.ReadAsStreamAsync(cancellationToken);
 
-			using var streamCopier = new MinecraftServerDownloadStreamCopier(progressCallback, info.Size.Bytes);
+			using var streamCopier = new MinecraftServerDownloadStreamCopier(progressCallback, fileDownloadInfo.Size.Bytes);
 			downloadedFileHash = await streamCopier.Copy(responseStream, fileStream, cancellationToken);
 		} catch (OperationCanceledException) {
 			throw;
@@ -154,8 +118,8 @@ sealed class MinecraftServerExecutableDownloader {
 			throw StopProcedureException.Instance;
 		}
 
-		if (!downloadedFileHash.Equals(info.Hash)) {
-			Logger.Error("Downloaded server executable has mismatched SHA1 hash. Expected {Expected}, got {Actual}.", info.Hash, downloadedFileHash);
+		if (!downloadedFileHash.Equals(fileDownloadInfo.Hash)) {
+			Logger.Error("Downloaded server executable has mismatched SHA1 hash. Expected {Expected}, got {Actual}.", fileDownloadInfo.Hash, downloadedFileHash);
 			throw StopProcedureException.Instance;
 		}
 	}
@@ -170,83 +134,6 @@ sealed class MinecraftServerExecutableDownloader {
 		}
 	}
 
-	private static string GetVersionMetadataUrlFromManifest(string serverVersion, JsonElement versionManifest) {
-		JsonElement versionsElement = GetJsonPropertyOrThrow(versionManifest, "versions", JsonValueKind.Array, "version manifest");
-		JsonElement versionElement;
-		try {
-			versionElement = versionsElement.EnumerateArray().Single(ele => ele.TryGetProperty("id", out var id) && id.ValueKind == JsonValueKind.String && id.GetString() == serverVersion);
-		} catch (Exception) {
-			Logger.Error("Version {Version} was not found in version manifest.", serverVersion);
-			throw StopProcedureException.Instance;
-		}
-
-		JsonElement urlElement = GetJsonPropertyOrThrow(versionElement, "url", JsonValueKind.String, "version entry in version manifest");
-		string? url = urlElement.GetString();
-
-		if (!Uri.TryCreate(url, UriKind.Absolute, out var uri)) {
-			Logger.Error("The \"url\" key in version entry in version manifest does not contain a valid URL: {Url}", url);
-			throw StopProcedureException.Instance;
-		}
-
-		if (uri.Scheme != "https" || !uri.AbsolutePath.EndsWith(".json", StringComparison.OrdinalIgnoreCase)) {
-			Logger.Error("The \"url\" key in version entry in version manifest does not contain a accepted URL: {Url}", url);
-			throw StopProcedureException.Instance;
-		}
-
-		return url;
-	}
-
-	private static ServerExecutableInfo GetServerExecutableUrlFromMetadata(JsonElement versionMetadata) {
-		JsonElement downloadsElement = GetJsonPropertyOrThrow(versionMetadata, "downloads", JsonValueKind.Object, "version metadata");
-		JsonElement serverElement = GetJsonPropertyOrThrow(downloadsElement, "server", JsonValueKind.Object, "downloads object in version metadata");
-		JsonElement urlElement = GetJsonPropertyOrThrow(serverElement, "url", JsonValueKind.String, "downloads.server object in version metadata");
-		string? url = urlElement.GetString();
-
-		if (!Uri.TryCreate(url, UriKind.Absolute, out var uri)) {
-			Logger.Error("The \"url\" key in downloads.server object in version metadata does not contain a valid URL: {Url}", url);
-			throw StopProcedureException.Instance;
-		}
-
-		if (uri.Scheme != "https" || !uri.AbsolutePath.EndsWith(".jar", StringComparison.OrdinalIgnoreCase)) {
-			Logger.Error("The \"url\" key in downloads.server object in version metadata does not contain a accepted URL: {Url}", url);
-			throw StopProcedureException.Instance;
-		}
-
-		JsonElement sizeElement = GetJsonPropertyOrThrow(serverElement, "size", JsonValueKind.Number, "downloads.server object in version metadata");
-		ulong size;
-		try {
-			size = sizeElement.GetUInt64();
-		} catch (FormatException) {
-			Logger.Error("The \"size\" key in downloads.server object in version metadata contains an invalid file size: {Size}", sizeElement);
-			throw StopProcedureException.Instance;
-		}
-
-		JsonElement sha1Element = GetJsonPropertyOrThrow(serverElement, "sha1", JsonValueKind.String, "downloads.server object in version metadata");
-		Sha1String hash;
-		try {
-			hash = Sha1String.FromString(sha1Element.GetString());
-		} catch (Exception) {
-			Logger.Error("The \"sha1\" key in downloads.server object in version metadata does not contain a valid SHA-1 hash: {Sha1}", sha1Element.GetString());
-			throw StopProcedureException.Instance;
-		}
-
-		return new ServerExecutableInfo(url, hash, new FileSize(size));
-	}
-
-	private static JsonElement GetJsonPropertyOrThrow(JsonElement parentElement, string propertyKey, JsonValueKind expectedKind, string location) {
-		if (!parentElement.TryGetProperty(propertyKey, out var valueElement)) {
-			Logger.Error("Missing \"{Property}\" key in " + location + ".", propertyKey);
-			throw StopProcedureException.Instance;
-		}
-
-		if (valueElement.ValueKind != expectedKind) {
-			Logger.Error("The \"{Property}\" key in " + location + " does not contain a JSON {ExpectedType}. Actual type: {ActualType}", propertyKey, expectedKind, valueElement.ValueKind);
-			throw StopProcedureException.Instance;
-		}
-
-		return valueElement;
-	}
-
 	private sealed class MinecraftServerDownloadStreamCopier : IDisposable {
 		private readonly StreamCopier streamCopier = new ();
 		private readonly IncrementalHash sha1 = IncrementalHash.CreateHash(HashAlgorithmName.SHA1);
@@ -278,10 +165,4 @@ sealed class MinecraftServerExecutableDownloader {
 			streamCopier.Dispose();
 		}
 	}
-
-	private sealed class StopProcedureException : Exception {
-		public static StopProcedureException Instance { get; } = new ();
-
-		private StopProcedureException() {}
-	}
 }

Agent/Phantom.Agent.Minecraft/Server/MinecraftServerExecutables.cs

@@ -1,13 +1,16 @@
 using System.Text.RegularExpressions;
+using Phantom.Common.Data.Minecraft;
 using Phantom.Common.Logging;
+using Phantom.Utils.IO;
 using Serilog;
 
 namespace Phantom.Agent.Minecraft.Server;
 
-public sealed class MinecraftServerExecutables {
+public sealed partial class MinecraftServerExecutables {
 	private static readonly ILogger Logger = PhantomLogger.Create<MinecraftServerExecutables>();
 
-	private static readonly Regex VersionFolderSanitizeRegex = new (@"[^a-zA-Z0-9_\-\.]", RegexOptions.Compiled);
+	[GeneratedRegex(@"[^a-zA-Z0-9_\-\.]", RegexOptions.Compiled)]
+	private static partial Regex VersionFolderSanitizeRegex();
 
 	private readonly string basePath;
 	private readonly Dictionary<string, MinecraftServerExecutableDownloader> runningDownloadersByVersion = new ();
@@ -16,16 +19,21 @@ public sealed class MinecraftServerExecutables {
 		this.basePath = basePath;
 	}
 
-	internal async Task<string?> DownloadAndGetPath(string version, EventHandler<DownloadProgressEventArgs> progressEventHandler, CancellationToken cancellationToken) {
-		string serverExecutableFolderPath = Path.Combine(basePath, VersionFolderSanitizeRegex.Replace(version, "_"));
+	internal async Task<string?> DownloadAndGetPath(FileDownloadInfo? fileDownloadInfo, string minecraftVersion, EventHandler<DownloadProgressEventArgs> progressEventHandler, CancellationToken cancellationToken) {
+		string serverExecutableFolderPath = Path.Combine(basePath, VersionFolderSanitizeRegex().Replace(minecraftVersion, "_"));
 		string serverExecutableFilePath = Path.Combine(serverExecutableFolderPath, "server.jar");
 
 		if (File.Exists(serverExecutableFilePath)) {
 			return serverExecutableFilePath;
 		}
 
+		if (fileDownloadInfo == null) {
+			Logger.Error("Unable to download server executable for version {Version} because no download info was provided.", minecraftVersion);
+			return null;
+		}
+
 		try {
-			Directory.CreateDirectory(serverExecutableFolderPath);
+			Directories.Create(serverExecutableFolderPath, Chmod.URWX_GRX);
 		} catch (Exception e) {
 			Logger.Error(e, "Unable to create folder for server executable: {ServerExecutableFolderPath}", serverExecutableFolderPath);
 			return null;
@@ -35,19 +43,19 @@ public sealed class MinecraftServerExecutables {
 		MinecraftServerExecutableDownloadListener listener = new (progressEventHandler, cancellationToken);
 
 		lock (this) {
-			if (runningDownloadersByVersion.TryGetValue(version, out downloader)) {
-				Logger.Information("A download for server version {Version} is already running, waiting for it to finish...", version);
+			if (runningDownloadersByVersion.TryGetValue(minecraftVersion, out downloader)) {
+				Logger.Information("A download for server version {Version} is already running, waiting for it to finish...", minecraftVersion);
 				downloader.Register(listener);
 			}
 			else {
-				downloader = new MinecraftServerExecutableDownloader(version, serverExecutableFilePath, listener);
+				downloader = new MinecraftServerExecutableDownloader(fileDownloadInfo, minecraftVersion, serverExecutableFilePath, listener);
 				downloader.Completed += (_, _) => {
 					lock (this) {
-						runningDownloadersByVersion.Remove(version);
+						runningDownloadersByVersion.Remove(minecraftVersion);
 					}
 				};
 
-				runningDownloadersByVersion[version] = downloader;
+				runningDownloadersByVersion[minecraftVersion] = downloader;
 			}
 		}
 

Agent/Phantom.Agent.Minecraft/Server/ServerExecutableInfo.cs

@@ -1,10 +0,0 @@
-using Phantom.Utils.Cryptography;
-using Phantom.Utils.IO;
-
-namespace Phantom.Agent.Minecraft.Server; 
-
-sealed record ServerExecutableInfo(
-	string DownloadUrl,
-	Sha1String Hash,
-	FileSize Size
-);

Agent/Phantom.Agent.Minecraft/Server/ServerStatusProtocol.cs

@@ -0,0 +1,93 @@
+using System.Buffers;
+using System.Buffers.Binary;
+using System.Net;
+using System.Net.Sockets;
+using System.Text;
+using Phantom.Common.Logging;
+using Serilog;
+
+namespace Phantom.Agent.Minecraft.Server; 
+
+public sealed class ServerStatusProtocol {
+	private readonly ILogger logger;
+
+	public ServerStatusProtocol(string loggerName) {
+		this.logger = PhantomLogger.Create<ServerStatusProtocol>(loggerName);
+	}
+
+	public async Task<int?> GetOnlinePlayerCount(int serverPort, CancellationToken cancellationToken) {
+		try {
+			return await GetOnlinePlayerCountOrThrow(serverPort, cancellationToken);
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while checking if players are online.");
+			return null;
+		}
+	}
+
+	private async Task<int?> GetOnlinePlayerCountOrThrow(int serverPort, CancellationToken cancellationToken) {
+		using var tcpClient = new TcpClient();
+		await tcpClient.ConnectAsync(IPAddress.Loopback, serverPort, cancellationToken);
+		var tcpStream = tcpClient.GetStream();
+		
+		// https://wiki.vg/Server_List_Ping
+		tcpStream.WriteByte(0xFE);
+		await tcpStream.FlushAsync(cancellationToken);
+
+		short? messageLength = await ReadStreamHeader(tcpStream, cancellationToken);
+		return messageLength == null ? null : await ReadOnlinePlayerCount(tcpStream, messageLength.Value * 2, cancellationToken);
+	}
+
+	private async Task<short?> ReadStreamHeader(NetworkStream tcpStream, CancellationToken cancellationToken) {
+		var headerBuffer = ArrayPool<byte>.Shared.Rent(3);
+		try {
+			await tcpStream.ReadExactlyAsync(headerBuffer, 0, 3, cancellationToken);
+
+			if (headerBuffer[0] != 0xFF) {
+				logger.Error("Unexpected first byte in response from server: {FirstByte}.", headerBuffer[0]);
+				return null;
+			}
+
+			short messageLength = BinaryPrimitives.ReadInt16BigEndian(headerBuffer.AsSpan(1));
+			if (messageLength <= 0) {
+				logger.Error("Unexpected message length in response from server: {MessageLength}.", messageLength);
+				return null;
+			}
+			
+			return messageLength;
+		} finally {
+			ArrayPool<byte>.Shared.Return(headerBuffer);
+		}
+	}
+
+	private async Task<int?> ReadOnlinePlayerCount(NetworkStream tcpStream, int messageLength, CancellationToken cancellationToken) {
+		var messageBuffer = ArrayPool<byte>.Shared.Rent(messageLength);
+		try {
+			await tcpStream.ReadExactlyAsync(messageBuffer, 0, messageLength, cancellationToken);
+
+			// Valid response separator encoded in UTF-16BE is 0x00 0xA7 (§).
+			const byte SeparatorSecondByte = 0xA7;
+			
+			static bool IsValidSeparator(ReadOnlySpan<byte> buffer, int index) {
+				return index > 0 && buffer[index - 1] == 0x00;
+			}
+			
+			int separator2 = Array.LastIndexOf(messageBuffer, SeparatorSecondByte);
+			int separator1 = separator2 == -1 ? -1 : Array.LastIndexOf(messageBuffer, SeparatorSecondByte, separator2 - 1);
+			if (!IsValidSeparator(messageBuffer, separator1) || !IsValidSeparator(messageBuffer, separator2)) {
+				logger.Error("Could not find message separators in response from server.");
+				return null;
+			}
+
+			string onlinePlayerCountStr = Encoding.BigEndianUnicode.GetString(messageBuffer[(separator1 + 1)..(separator2 - 1)]);
+			if (!int.TryParse(onlinePlayerCountStr, out int onlinePlayerCount)) {
+				logger.Error("Could not parse online player count in response from server: {OnlinePlayerCount}.", onlinePlayerCountStr);
+				return null;
+			}
+			
+			logger.Debug("Detected {OnlinePlayerCount} online player(s).", onlinePlayerCount);
+			return onlinePlayerCount;
+		} finally {
+			ArrayPool<byte>.Shared.Return(messageBuffer);
+		}
+	}
+}

Agent/Phantom.Agent.Rpc/KeepAliveLoop.cs

@@ -0,0 +1,40 @@
+using Phantom.Common.Logging;
+using Phantom.Common.Messages.ToServer;
+using Serilog;
+
+namespace Phantom.Agent.Rpc;
+
+sealed class KeepAliveLoop {
+	private static readonly ILogger Logger = PhantomLogger.Create<KeepAliveLoop>();
+
+	private static readonly TimeSpan KeepAliveInterval = TimeSpan.FromSeconds(10);
+
+	private readonly RpcServerConnection connection;
+	private readonly CancellationTokenSource cancellationTokenSource = new ();
+
+	public KeepAliveLoop(RpcServerConnection connection) {
+		this.connection = connection;
+		Task.Run(Run);
+	}
+
+	private async Task Run() {
+		var cancellationToken = cancellationTokenSource.Token;
+
+		Logger.Information("Started keep-alive loop.");
+		try {
+			while (true) {
+				await Task.Delay(KeepAliveInterval, cancellationToken);
+				await connection.Send(new AgentIsAliveMessage());
+			}
+		} catch (OperationCanceledException) {
+			// Ignore.
+		} finally {
+			cancellationTokenSource.Dispose();
+			Logger.Information("Stopped keep-alive loop.");
+		}
+	}
+
+	public void Cancel() {
+		cancellationTokenSource.Cancel();
+	}
+}

Agent/Phantom.Agent.Rpc/Phantom.Agent.Rpc.csproj

@@ -6,10 +6,6 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
   
-  <ItemGroup>
-    <PackageReference Include="Serilog" Version="2.12.0" />
-  </ItemGroup>
-  
   <ItemGroup>
     <ProjectReference Include="..\..\Common\Phantom.Common.Messages\Phantom.Common.Messages.csproj" />
   </ItemGroup>

Agent/Phantom.Agent.Rpc/RpcExtensions.cs

@@ -1,19 +0,0 @@
-using NetMQ;
-using NetMQ.Sockets;
-using Phantom.Common.Messages;
-using Phantom.Common.Messages.ToServer;
-
-namespace Phantom.Agent.Rpc; 
-
-public static class RpcExtensions {
-	internal static async Task SendMessage<TMessage>(this ClientSocket socket, TMessage message) where TMessage : IMessageToServer {
-		byte[] bytes = MessageRegistries.ToServer.Write(message).ToArray();
-		if (bytes.Length > 0) {
-			await socket.SendAsync(bytes);
-		}
-	}
-	
-	public static Task SendSimpleReply<TMessage, TReplyEnum>(this ClientSocket socket, TMessage message, TReplyEnum reply) where TMessage : IMessageWithReply where TReplyEnum : Enum {
-		return SendMessage(socket, SimpleReplyMessage.FromEnum(message.SequenceId, reply));
-	}
-}

Agent/Phantom.Agent.Rpc/RpcLauncher.cs

@@ -2,14 +2,18 @@
 using NetMQ.Sockets;
 using Phantom.Common.Data.Agent;
 using Phantom.Common.Messages;
+using Phantom.Common.Messages.BiDirectional;
 using Phantom.Common.Messages.ToServer;
 using Phantom.Utils.Rpc;
+using Phantom.Utils.Rpc.Message;
+using Phantom.Utils.Runtime;
+using Serilog;
 using Serilog.Events;
 
 namespace Phantom.Agent.Rpc;
 
 public sealed class RpcLauncher : RpcRuntime<ClientSocket> {
-	public static async Task Launch(RpcConfiguration config, AgentAuthToken authToken, AgentInfo agentInfo, Func<ClientSocket, IMessageToAgentListener> listenerFactory) {
+	public static async Task Launch(RpcConfiguration config, AgentAuthToken authToken, AgentInfo agentInfo, Func<RpcServerConnection, IMessageToAgentListener> listenerFactory, SemaphoreSlim disconnectSemaphore, CancellationToken receiveCancellationToken) {
 		var socket = new ClientSocket();
 		var options = socket.Options;
 
@@ -17,21 +21,26 @@ public sealed class RpcLauncher : RpcRuntime<ClientSocket> {
 		options.CurveCertificate = new NetMQCertificate();
 		options.HelloMessage = MessageRegistries.ToServer.Write(new RegisterAgentMessage(authToken, agentInfo)).ToArray();
 
-		await new RpcLauncher(config, socket, agentInfo.Guid, listenerFactory).Launch();
+		await new RpcLauncher(config, socket, agentInfo.Guid, listenerFactory, disconnectSemaphore, receiveCancellationToken).Launch();
 	}
 
 	private readonly RpcConfiguration config;
 	private readonly Guid agentGuid;
-	private readonly Func<ClientSocket, IMessageToAgentListener> messageListenerFactory;
+	private readonly Func<RpcServerConnection, IMessageToAgentListener> messageListenerFactory;
 
-	private RpcLauncher(RpcConfiguration config, ClientSocket socket, Guid agentGuid, Func<ClientSocket, IMessageToAgentListener> messageListenerFactory) : base(socket, config.CancellationToken) {
+	private readonly SemaphoreSlim disconnectSemaphore;
+	private readonly CancellationToken receiveCancellationToken;
+
+	private RpcLauncher(RpcConfiguration config, ClientSocket socket, Guid agentGuid, Func<RpcServerConnection, IMessageToAgentListener> messageListenerFactory, SemaphoreSlim disconnectSemaphore, CancellationToken receiveCancellationToken) : base(config, socket) {
 		this.config = config;
 		this.agentGuid = agentGuid;
 		this.messageListenerFactory = messageListenerFactory;
+		this.disconnectSemaphore = disconnectSemaphore;
+		this.receiveCancellationToken = receiveCancellationToken;
 	}
 
 	protected override void Connect(ClientSocket socket) {
-		var logger = config.Logger;
+		var logger = config.RuntimeLogger;
 		var url = config.TcpUrl;
 
 		logger.Information("Starting ZeroMQ client and connecting to {Url}...", url);
@@ -39,35 +48,60 @@ public sealed class RpcLauncher : RpcRuntime<ClientSocket> {
 		logger.Information("ZeroMQ client ready.");
 	}
 
-	protected override async Task Run(ClientSocket socket, CancellationToken cancellationToken) {
-		var logger = config.Logger;
+	protected override void Run(ClientSocket socket, MessageReplyTracker replyTracker, TaskManager taskManager) {
+		var connection = new RpcServerConnection(socket, replyTracker);
+		ServerMessaging.SetCurrentConnection(connection);
 		
-		var listener = messageListenerFactory(socket);
+		var logger = config.RuntimeLogger;
+		var handler = new MessageToAgentHandler(messageListenerFactory(connection), logger, taskManager, receiveCancellationToken);
+		var keepAliveLoop = new KeepAliveLoop(connection);
 
-		ServerMessaging.SetCurrentSocket(socket, cancellationToken);
+		try {
+			while (!receiveCancellationToken.IsCancellationRequested) {
+				var data = socket.Receive(receiveCancellationToken);
 				
-		// TODO optimize msg
-		await foreach (var bytes in socket.ReceiveBytesAsyncEnumerable(cancellationToken)) {
-			if (logger.IsEnabled(LogEventLevel.Verbose)) {
-				if (bytes.Length > 0 && MessageRegistries.ToAgent.TryGetType(bytes, out var type)) {
-					logger.Verbose("Received {MessageType} ({Bytes} B) from server.", type.Name, bytes.Length);
-				}
-				else {
-					logger.Verbose("Received {Bytes} B message from server.", bytes.Length);
+				LogMessageType(logger, data);
+				
+				if (data.Length > 0) {
+					MessageRegistries.ToAgent.Handle(data, handler);
 				}
 			}
+		} catch (OperationCanceledException) {
+			// Ignore.
+		} finally {
+			logger.Debug("ZeroMQ client stopped receiving messages.");
 
-			if (bytes.Length > 0) {
-				MessageRegistries.ToAgent.Handle(bytes, listener, cancellationToken);
-			}
+			disconnectSemaphore.Wait(CancellationToken.None);
+			keepAliveLoop.Cancel();
 		}
 	}
 
-	protected override async Task Disconnect(ClientSocket socket) {
-		var timeoutTask = Task.Delay(TimeSpan.FromSeconds(5));
-		var finishedTask = await Task.WhenAny(socket.SendMessage(new UnregisterAgentMessage(agentGuid)), timeoutTask);
-		if (finishedTask == timeoutTask) {
-			config.Logger.Error("Timed out communicating agent shutdown with the server.");
+	private static void LogMessageType(ILogger logger, ReadOnlyMemory<byte> data) {
+		if (!logger.IsEnabled(LogEventLevel.Verbose)) {
+			return;
+		}
+
+		if (data.Length > 0 && MessageRegistries.ToAgent.TryGetType(data, out var type)) {
+			logger.Verbose("Received {MessageType} ({Bytes} B) from server.", type.Name, data.Length);
+		}
+		else {
+			logger.Verbose("Received {Bytes} B message from server.", data.Length);
+		}
+	}
+
+	protected override async Task Disconnect() {
+		var unregisterTimeoutTask = Task.Delay(TimeSpan.FromSeconds(5), CancellationToken.None);
+		var finishedTask = await Task.WhenAny(ServerMessaging.Send(new UnregisterAgentMessage(agentGuid)), unregisterTimeoutTask);
+		if (finishedTask == unregisterTimeoutTask) {
+			config.RuntimeLogger.Error("Timed out communicating agent shutdown with the server.");
+		}
+	}
+
+	private sealed class MessageToAgentHandler : MessageHandler<IMessageToAgentListener> {
+		public MessageToAgentHandler(IMessageToAgentListener listener, ILogger logger, TaskManager taskManager, CancellationToken cancellationToken) : base(listener, logger, taskManager, cancellationToken) {}
+		
+		protected override Task SendReply(uint sequenceId, byte[] serializedReply) {
+			return ServerMessaging.Send(new ReplyMessage(sequenceId, serializedReply));
 		}
 	}
 }

Agent/Phantom.Agent.Rpc/RpcServerConnection.cs

@@ -0,0 +1,41 @@
+using NetMQ;
+using NetMQ.Sockets;
+using Phantom.Common.Messages;
+using Phantom.Common.Messages.BiDirectional;
+using Phantom.Utils.Rpc.Message;
+
+namespace Phantom.Agent.Rpc; 
+
+public sealed class RpcServerConnection {
+	private readonly ClientSocket socket;
+	private readonly MessageReplyTracker replyTracker;
+
+	internal RpcServerConnection(ClientSocket socket, MessageReplyTracker replyTracker) {
+		this.socket = socket;
+		this.replyTracker = replyTracker;
+	}
+
+	internal async Task Send<TMessage>(TMessage message) where TMessage : IMessageToServer {
+		var bytes = MessageRegistries.ToServer.Write(message).ToArray();
+		if (bytes.Length > 0) {
+			await socket.SendAsync(bytes);
+		}
+	}
+
+	internal async Task<TReply?> Send<TMessage, TReply>(TMessage message, TimeSpan waitForReplyTime, CancellationToken waitForReplyCancellationToken) where TMessage : IMessageToServer<TReply> where TReply : class {
+		var sequenceId = replyTracker.RegisterReply();
+		
+		var bytes = MessageRegistries.ToServer.Write<TMessage, TReply>(sequenceId, message).ToArray();
+		if (bytes.Length == 0) {
+			replyTracker.ForgetReply(sequenceId);
+			return null;
+		}
+
+		await socket.SendAsync(bytes);
+		return await replyTracker.WaitForReply<TReply>(sequenceId, waitForReplyTime, waitForReplyCancellationToken);
+	}
+
+	public void Receive(ReplyMessage message) {
+		replyTracker.ReceiveReply(message.SequenceId, message.SerializedReply);
+	}
+}

Agent/Phantom.Agent.Rpc/ServerMessaging.cs

@@ -1,55 +1,34 @@
-using NetMQ.Sockets;
-using Phantom.Common.Logging;
+using Phantom.Common.Logging;
 using Phantom.Common.Messages;
-using Phantom.Common.Messages.ToServer;
 using Serilog;
 
 namespace Phantom.Agent.Rpc;
 
 public static class ServerMessaging {
-	private static readonly ILogger Logger = PhantomLogger.Create(typeof(ServerMessaging));
+	private static readonly ILogger Logger = PhantomLogger.Create(nameof(ServerMessaging));
 	
-	private static readonly TimeSpan KeepAliveInterval = TimeSpan.FromSeconds(10);
+	private static RpcServerConnection? CurrentConnection { get; set; }
+	private static RpcServerConnection CurrentConnectionOrThrow => CurrentConnection ?? throw new InvalidOperationException("Server connection not ready.");
 	
-	private static ClientSocket? CurrentSocket { get; set; }
-	private static readonly object SetCurrentSocketLock = new ();
+	private static readonly object SetCurrentConnectionLock = new ();
 
-	internal static void SetCurrentSocket(ClientSocket socket, CancellationToken cancellationToken) {
-		Logger.Information("Server socket ready.");
-		
-		bool isFirstSet = false;
-		lock (SetCurrentSocketLock) {
-			if (CurrentSocket == null) {
-				isFirstSet = true;
+	internal static void SetCurrentConnection(RpcServerConnection connection) {
+		lock (SetCurrentConnectionLock) {
+			if (CurrentConnection != null) {
+				throw new InvalidOperationException("Server connection can only be set once.");
 			}
 			
-			CurrentSocket = socket;
+			CurrentConnection = connection;
 		}
 		
-		if (isFirstSet) {
-			Task.Factory.StartNew(static o => SendKeepAliveLoop((CancellationToken) o!), cancellationToken, cancellationToken, TaskCreationOptions.LongRunning, TaskScheduler.Default);
-		}
+		Logger.Information("Server connection ready.");
 	}
 
-	public static async Task SendMessage<TMessage>(TMessage message) where TMessage : IMessageToServer {
-		var currentSocket = CurrentSocket ?? throw new InvalidOperationException("Server socket not ready.");
-		await currentSocket.SendMessage(message);
+	public static Task Send<TMessage>(TMessage message) where TMessage : IMessageToServer {
+		return CurrentConnectionOrThrow.Send(message);
 	}
 
-	private static async Task SendKeepAliveLoop(CancellationToken cancellationToken) {
-		try {
-			while (true) {
-				await Task.Delay(KeepAliveInterval, cancellationToken);
-
-				var currentSocket = CurrentSocket;
-				if (currentSocket != null) {
-					await currentSocket.SendMessage(new AgentIsAliveMessage());
-				}
-			}
-		} catch (OperationCanceledException) {
-			// Ignore.
-		} finally {
-			Logger.Information("Stopped keep-alive loop.");
-		}
+	public static Task<TReply?> Send<TMessage, TReply>(TMessage message, TimeSpan waitForReplyTime, CancellationToken waitForReplyCancellationToken) where TMessage : IMessageToServer<TReply> where TReply : class {
+		return CurrentConnectionOrThrow.Send<TMessage, TReply>(message, waitForReplyTime, waitForReplyCancellationToken);
 	}
 }

Agent/Phantom.Agent.Services/AgentFolders.cs

@@ -9,6 +9,7 @@ public sealed class AgentFolders {
 
 	public string DataFolderPath { get; }
 	public string InstancesFolderPath { get; }
+	public string BackupsFolderPath { get; }
 
 	public string TemporaryFolderPath { get; }
 	public string ServerExecutableFolderPath { get; }
@@ -18,6 +19,7 @@ public sealed class AgentFolders {
 	public AgentFolders(string dataFolderPath, string temporaryFolderPath, string javaSearchFolderPath) {
 		this.DataFolderPath = Path.GetFullPath(dataFolderPath);
 		this.InstancesFolderPath = Path.Combine(DataFolderPath, "instances");
+		this.BackupsFolderPath = Path.Combine(DataFolderPath, "backups");
 		
 		this.TemporaryFolderPath = Path.GetFullPath(temporaryFolderPath);
 		this.ServerExecutableFolderPath = Path.Combine(TemporaryFolderPath, "servers");
@@ -28,6 +30,7 @@ public sealed class AgentFolders {
 	public bool TryCreate() {
 		return TryCreateFolder(DataFolderPath) &&
 		       TryCreateFolder(InstancesFolderPath) &&
+		       TryCreateFolder(BackupsFolderPath) &&
 		       TryCreateFolder(TemporaryFolderPath) &&
 		       TryCreateFolder(ServerExecutableFolderPath);
 	}

Agent/Phantom.Agent.Services/AgentServices.cs

@@ -1,19 +1,29 @@
 using Phantom.Agent.Minecraft.Java;
+using Phantom.Agent.Services.Backups;
 using Phantom.Agent.Services.Instances;
 using Phantom.Common.Data.Agent;
+using Phantom.Common.Logging;
+using Phantom.Utils.Runtime;
+using Serilog;
 
 namespace Phantom.Agent.Services;
 
 public sealed class AgentServices {
+	private static readonly ILogger Logger = PhantomLogger.Create<AgentServices>();
+	
 	private AgentFolders AgentFolders { get; }
+	private TaskManager TaskManager { get; }
+	private BackupManager BackupManager { get; }
 
 	internal JavaRuntimeRepository JavaRuntimeRepository { get; }
 	internal InstanceSessionManager InstanceSessionManager { get; }
 
 	public AgentServices(AgentInfo agentInfo, AgentFolders agentFolders) {
 		this.AgentFolders = agentFolders;
+		this.TaskManager = new TaskManager(PhantomLogger.Create<TaskManager, AgentServices>());
+		this.BackupManager = new BackupManager(agentFolders);
 		this.JavaRuntimeRepository = new JavaRuntimeRepository();
-		this.InstanceSessionManager = new InstanceSessionManager(agentInfo, agentFolders, JavaRuntimeRepository);
+		this.InstanceSessionManager = new InstanceSessionManager(agentInfo, agentFolders, JavaRuntimeRepository, TaskManager, BackupManager);
 	}
 
 	public async Task Initialize() {
@@ -23,6 +33,13 @@ public sealed class AgentServices {
 	}
 
 	public async Task Shutdown() {
+		Logger.Information("Stopping services...");
+		
 		await InstanceSessionManager.StopAll();
+		InstanceSessionManager.Dispose();
+		
+		await TaskManager.Stop();
+		
+		Logger.Information("Services stopped.");
 	}
 }

Agent/Phantom.Agent.Services/Backups/BackupArchiver.cs

@@ -0,0 +1,180 @@
+using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
+using System.Formats.Tar;
+using Phantom.Agent.Minecraft.Instance;
+using Phantom.Common.Data.Backups;
+using Phantom.Common.Logging;
+using Phantom.Utils.IO;
+using Serilog;
+
+namespace Phantom.Agent.Services.Backups; 
+
+sealed class BackupArchiver {
+	private readonly string destinationBasePath;
+	private readonly string temporaryBasePath;
+	private readonly ILogger logger;
+	private readonly InstanceProperties instanceProperties;
+	private readonly CancellationToken cancellationToken;
+	
+	public BackupArchiver(string destinationBasePath, string temporaryBasePath, string loggerName, InstanceProperties instanceProperties, CancellationToken cancellationToken) {
+		this.destinationBasePath = destinationBasePath;
+		this.temporaryBasePath = temporaryBasePath;
+		this.logger = PhantomLogger.Create<BackupArchiver>(loggerName);
+		this.instanceProperties = instanceProperties;
+		this.cancellationToken = cancellationToken;
+	}
+
+	private bool IsFolderSkipped(ImmutableList<string> relativePath) {
+		return relativePath is ["cache" or "crash-reports" or "debug" or "libraries" or "logs" or "mods" or "versions"];
+	}
+	
+	[SuppressMessage("ReSharper", "ConvertIfStatementToReturnStatement")]
+	private bool IsFileSkipped(ImmutableList<string> relativePath) {
+		var name = relativePath[^1];
+		
+		if (relativePath.Count == 2 && name == "session.lock") {
+			return true;
+		}
+
+		var extension = Path.GetExtension(name);
+		if (extension is ".jar" or ".zip") {
+			return true;
+		}
+		
+		return false;
+	}
+
+	public async Task<string?> ArchiveWorld(BackupCreationResult.Builder resultBuilder) {
+		string guid = instanceProperties.InstanceGuid.ToString();
+		string currentDateTime = DateTime.Now.ToString("yyyyMMdd-HHmmss");
+		string backupFolderPath = Path.Combine(destinationBasePath, guid);
+		string backupFilePath = Path.Combine(backupFolderPath, currentDateTime + ".tar");
+		
+		if (File.Exists(backupFilePath)) {
+			resultBuilder.Kind = BackupCreationResultKind.BackupFileAlreadyExists;
+			logger.Warning("Skipping backup, file already exists: {File}", backupFilePath);
+			return null;
+		}
+		
+		try {
+			Directories.Create(backupFolderPath, Chmod.URWX_GRX);
+		} catch (Exception e) {
+			resultBuilder.Kind = BackupCreationResultKind.CouldNotCreateBackupFolder;
+			logger.Error(e, "Could not create backup folder: {Folder}", backupFolderPath);
+			return null;
+		}
+
+		string temporaryFolderPath = Path.Combine(temporaryBasePath, guid + "_" + currentDateTime);
+		if (!await CopyWorldAndCreateTarArchive(temporaryFolderPath, backupFilePath, resultBuilder)) {
+			return null;
+		}
+		
+		logger.Debug("Created world backup: {FilePath}", backupFilePath);
+		return backupFilePath;
+	}
+
+	private async Task<bool> CopyWorldAndCreateTarArchive(string temporaryFolderPath, string backupFilePath, BackupCreationResult.Builder resultBuilder) {
+		try {
+			if (!await CopyWorldToTemporaryFolder(temporaryFolderPath)) {
+				resultBuilder.Kind = BackupCreationResultKind.CouldNotCopyWorldToTemporaryFolder;
+				return false;
+			}
+
+			if (!await CreateTarArchive(temporaryFolderPath, backupFilePath)) {
+				resultBuilder.Kind = BackupCreationResultKind.CouldNotCreateWorldArchive;
+				return false;
+			}
+
+			return true;
+		} finally {
+			try {
+				Directory.Delete(temporaryFolderPath, recursive: true);
+			} catch (Exception e) {
+				resultBuilder.Warnings |= BackupCreationWarnings.CouldNotDeleteTemporaryFolder;
+				logger.Error(e, "Could not delete temporary world folder: {Folder}", temporaryFolderPath);
+			}
+		}
+	}
+
+	private async Task<bool> CopyWorldToTemporaryFolder(string temporaryFolderPath) {
+		try {
+			await CopyDirectory(new DirectoryInfo(instanceProperties.InstanceFolder), temporaryFolderPath, ImmutableList<string>.Empty);
+			return true;
+		} catch (Exception e) {
+			logger.Error(e, "Could not copy world to temporary folder.");
+			return false;
+		}
+	}
+
+	private async Task<bool> CreateTarArchive(string sourceFolderPath, string backupFilePath) {
+		try {
+			await TarFile.CreateFromDirectoryAsync(sourceFolderPath, backupFilePath, false, cancellationToken);
+			return true;
+		} catch (Exception e) {
+			logger.Error(e, "Could not create archive.");
+			DeleteBrokenArchiveFile(backupFilePath);
+			return false;
+		}
+	}
+
+	private void DeleteBrokenArchiveFile(string filePath) {
+		if (File.Exists(filePath)) {
+			try {
+				File.Delete(filePath);
+			} catch (Exception e) {
+				logger.Error(e, "Could not delete broken archive: {File}", filePath);
+			}
+		}
+	}
+
+	private async Task CopyDirectory(DirectoryInfo sourceFolder, string destinationFolderPath, ImmutableList<string> relativePath) {
+		cancellationToken.ThrowIfCancellationRequested();
+
+		bool needsToCreateFolder = true;
+		
+		foreach (FileInfo file in sourceFolder.EnumerateFiles()) {
+			var filePath = relativePath.Add(file.Name);
+			if (IsFileSkipped(filePath)) {
+				logger.Debug("Skipping file: {File}", string.Join('/', filePath));
+				continue;
+			}
+
+			if (needsToCreateFolder) {
+				needsToCreateFolder = false;
+				Directories.Create(destinationFolderPath, Chmod.URWX);
+			}
+
+			await CopyFileWithRetries(file, destinationFolderPath);
+		}
+
+		foreach (DirectoryInfo directory in sourceFolder.EnumerateDirectories()) {
+			var folderPath = relativePath.Add(directory.Name);
+			if (IsFolderSkipped(folderPath)) {
+				logger.Debug("Skipping folder: {Folder}", string.Join('/', folderPath));
+				continue;
+			}
+			
+			await CopyDirectory(directory, Path.Join(destinationFolderPath, directory.Name), folderPath);
+		}
+	}
+
+	private async Task CopyFileWithRetries(FileInfo sourceFile, string destinationFolderPath) {
+		var destinationFilePath = Path.Combine(destinationFolderPath, sourceFile.Name);
+		
+		const int TotalAttempts = 10;
+		for (int attempt = 1; attempt <= TotalAttempts; attempt++) {
+			try {
+				sourceFile.CopyTo(destinationFilePath);
+				return;
+			} catch (IOException) {
+				if (attempt == TotalAttempts) {
+					throw;
+				}
+				else {
+					logger.Warning("Failed copying file {File}, retrying...", sourceFile.FullName);
+					await Task.Delay(200, cancellationToken);
+				}
+			}
+		}
+	}
+}

Agent/Phantom.Agent.Services/Backups/BackupCompressor.cs

@@ -0,0 +1,69 @@
+using Phantom.Common.Logging;
+using Phantom.Utils.Runtime;
+using Serilog;
+
+namespace Phantom.Agent.Services.Backups; 
+
+static class BackupCompressor {
+	private static ILogger Logger { get; } = PhantomLogger.Create(nameof(BackupCompressor));
+	private static ILogger ZstdLogger { get; } = PhantomLogger.Create(nameof(BackupCompressor), "Zstd");
+	
+	private const string Quality = "-10";
+	private const string Memory = "--long=26";
+	private const string Threads = "-T3";
+	
+	public static async Task<string?> Compress(string sourceFilePath, CancellationToken cancellationToken) {
+		if (sourceFilePath.Contains('"')) {
+			Logger.Error("Could not compress backup, archive path contains quotes: {Path}", sourceFilePath);
+			return null;
+		}
+		
+		var destinationFilePath = sourceFilePath + ".zst";
+
+		if (!await TryCompressFile(sourceFilePath, destinationFilePath, cancellationToken)) {
+			try {
+				File.Delete(destinationFilePath);
+			} catch (Exception e) {
+				Logger.Error(e, "Could not delete compresed archive after unsuccessful compression: {Path}", destinationFilePath);
+			}
+
+			return null;
+		}
+
+		return destinationFilePath;
+	}
+
+	private static async Task<bool> TryCompressFile(string sourceFilePath, string destinationFilePath, CancellationToken cancellationToken) {
+		var workingDirectory = Path.GetDirectoryName(sourceFilePath);
+		if (string.IsNullOrEmpty(workingDirectory)) {
+			Logger.Error("Invalid destination path: {Path}", destinationFilePath);
+			return false;
+		}
+
+		var launcher = new ProcessConfigurator {
+			FileName = "zstd",
+			WorkingDirectory = workingDirectory,
+			ArgumentList = {
+				Quality,
+				Memory,
+				Threads,
+				"-c",
+				"--rm",
+				"--no-progress",
+				"-c",
+				"-o", destinationFilePath,
+				"--", sourceFilePath
+			}
+		};
+
+		static void OnZstdOutput(object? sender, Process.Output output) {
+			if (!string.IsNullOrWhiteSpace(output.Line)) {
+				ZstdLogger.Debug("[Output] {Line}", output.Line);
+			}
+		}
+
+		var process = new OneShotProcess(ZstdLogger, launcher);
+		process.OutputReceived += OnZstdOutput;
+		return await process.Run(cancellationToken);
+	}
+}

Agent/Phantom.Agent.Services/Backups/BackupManager.cs

@@ -0,0 +1,118 @@
+using Phantom.Agent.Minecraft.Instance;
+using Phantom.Common.Data.Backups;
+using Phantom.Common.Logging;
+using Serilog;
+
+namespace Phantom.Agent.Services.Backups;
+
+sealed class BackupManager {
+	private readonly string destinationBasePath;
+	private readonly string temporaryBasePath;
+
+	public BackupManager(AgentFolders agentFolders) {
+		this.destinationBasePath = agentFolders.BackupsFolderPath;
+		this.temporaryBasePath = Path.Combine(agentFolders.TemporaryFolderPath, "backups");
+	}
+
+	public async Task<BackupCreationResult> CreateBackup(string loggerName, InstanceProcess process, CancellationToken cancellationToken) {
+		try {
+			if (!await process.BackupSemaphore.Wait(TimeSpan.FromSeconds(1), cancellationToken)) {
+				return new BackupCreationResult(BackupCreationResultKind.BackupAlreadyRunning);
+			}
+		} catch (ObjectDisposedException) {
+			return new BackupCreationResult(BackupCreationResultKind.InstanceNotRunning);
+		} catch (OperationCanceledException) {
+			return new BackupCreationResult(BackupCreationResultKind.InstanceNotRunning);
+		}
+
+		try {
+			return await new BackupCreator(destinationBasePath, temporaryBasePath, loggerName, process, cancellationToken).CreateBackup();
+		} finally {
+			process.BackupSemaphore.Release();
+		}
+	}
+
+	private sealed class BackupCreator {
+		private readonly string destinationBasePath;
+		private readonly string temporaryBasePath;
+		private readonly string loggerName;
+		private readonly ILogger logger;
+		private readonly InstanceProcess process;
+		private readonly CancellationToken cancellationToken;
+
+		public BackupCreator(string destinationBasePath, string temporaryBasePath, string loggerName, InstanceProcess process, CancellationToken cancellationToken) {
+			this.destinationBasePath = destinationBasePath;
+			this.temporaryBasePath = temporaryBasePath;
+			this.loggerName = loggerName;
+			this.logger = PhantomLogger.Create<BackupManager>(loggerName);
+			this.process = process;
+			this.cancellationToken = cancellationToken;
+		}
+
+		public async Task<BackupCreationResult> CreateBackup() {
+			logger.Information("Backup started.");
+			
+			var resultBuilder = new BackupCreationResult.Builder();
+			string? backupFilePath;
+			
+			using (var dispatcher = new BackupServerCommandDispatcher(logger, process, cancellationToken)) {
+				backupFilePath = await CreateWorldArchive(dispatcher, resultBuilder);
+			}
+			
+			if (backupFilePath != null) {
+				await CompressWorldArchive(backupFilePath, resultBuilder);
+			}
+			
+			var result = resultBuilder.Build();
+			LogBackupResult(result);
+			return result;
+		}
+
+		private async Task<string?> CreateWorldArchive(BackupServerCommandDispatcher dispatcher, BackupCreationResult.Builder resultBuilder) {
+			try {
+				await dispatcher.DisableAutomaticSaving();
+				await dispatcher.SaveAllChunks();
+				return await new BackupArchiver(destinationBasePath, temporaryBasePath, loggerName, process.InstanceProperties, cancellationToken).ArchiveWorld(resultBuilder);
+			} catch (OperationCanceledException) {
+				resultBuilder.Kind = BackupCreationResultKind.BackupCancelled;
+				logger.Warning("Backup creation was cancelled.");
+				return null;
+			} catch (Exception e) {
+				resultBuilder.Kind = BackupCreationResultKind.UnknownError;
+				logger.Error(e, "Caught exception while creating an instance backup.");
+				return null;
+			} finally {
+				try {
+					await dispatcher.EnableAutomaticSaving();
+				} catch (OperationCanceledException) {
+					// ignore
+				} catch (Exception e) {
+					resultBuilder.Warnings |= BackupCreationWarnings.CouldNotRestoreAutomaticSaving;
+					logger.Error(e, "Caught exception while enabling automatic saving after creating an instance backup.");
+				}
+			}
+		}
+
+		private async Task CompressWorldArchive(string filePath, BackupCreationResult.Builder resultBuilder) {
+			var compressedFilePath = await BackupCompressor.Compress(filePath, cancellationToken);
+			if (compressedFilePath == null) {
+				resultBuilder.Warnings |= BackupCreationWarnings.CouldNotCompressWorldArchive;
+			}
+		}
+
+		private void LogBackupResult(BackupCreationResult result) {
+			if (result.Kind != BackupCreationResultKind.Success) {
+				logger.Warning("Backup failed: {Reason}", result.Kind.ToSentence());
+				return;
+			}
+			
+			var warningCount = result.Warnings.Count();
+			if (warningCount > 0) {
+				logger.Warning("Backup finished with {Warnings} warning(s).", warningCount);
+			}
+			else {
+				logger.Information("Backup finished successfully.");
+			}
+		}
+	}
+}

Agent/Phantom.Agent.Services/Backups/BackupScheduler.cs

@@ -0,0 +1,96 @@
+using Phantom.Agent.Minecraft.Instance;
+using Phantom.Agent.Minecraft.Server;
+using Phantom.Common.Data.Backups;
+using Phantom.Common.Logging;
+using Phantom.Utils.Runtime;
+
+namespace Phantom.Agent.Services.Backups;
+
+sealed class BackupScheduler : CancellableBackgroundTask {
+	// TODO make configurable
+	private static readonly TimeSpan InitialDelay = TimeSpan.FromMinutes(2);
+	private static readonly TimeSpan BackupInterval = TimeSpan.FromMinutes(30);
+	private static readonly TimeSpan BackupFailureRetryDelay = TimeSpan.FromMinutes(5);
+
+	private readonly string loggerName;
+	private readonly BackupManager backupManager;
+	private readonly InstanceProcess process;
+	private readonly int serverPort;
+	private readonly ServerStatusProtocol serverStatusProtocol;
+	private readonly ManualResetEventSlim serverOutputWhileWaitingForOnlinePlayers = new ();
+	
+	public event EventHandler<BackupCreationResult>? BackupCompleted; 
+
+	public BackupScheduler(TaskManager taskManager, BackupManager backupManager, InstanceProcess process, int serverPort, string loggerName) : base(PhantomLogger.Create<BackupScheduler>(loggerName), taskManager, "Backup scheduler for " + loggerName) {
+		this.loggerName = loggerName;
+		this.backupManager = backupManager;
+		this.process = process;
+		this.serverPort = serverPort;
+		this.serverStatusProtocol = new ServerStatusProtocol(loggerName);
+	}
+
+	protected override async Task RunTask() {
+		await Task.Delay(InitialDelay, CancellationToken);
+		Logger.Information("Starting a new backup after server launched.");
+			
+		while (!CancellationToken.IsCancellationRequested) {
+			var result = await CreateBackup();
+			BackupCompleted?.Invoke(this, result);
+			
+			if (result.Kind.ShouldRetry()) {
+				Logger.Warning("Scheduled backup failed, retrying in {Minutes} minutes.", BackupFailureRetryDelay.TotalMinutes);
+				await Task.Delay(BackupFailureRetryDelay, CancellationToken);
+			}
+			else {
+				Logger.Information("Scheduling next backup in {Minutes} minutes.", BackupInterval.TotalMinutes);
+				await Task.Delay(BackupInterval, CancellationToken);
+				await WaitForOnlinePlayers();
+			}
+		}
+	}
+
+	private async Task<BackupCreationResult> CreateBackup() {
+		return await backupManager.CreateBackup(loggerName, process, CancellationToken.None);
+	}
+
+	private async Task WaitForOnlinePlayers() {
+		bool needsToLogOfflinePlayersMessage = true;
+		
+		process.AddOutputListener(ServerOutputListener, maxLinesToReadFromHistory: 0);
+		try {
+			while (!CancellationToken.IsCancellationRequested) {
+				serverOutputWhileWaitingForOnlinePlayers.Reset();
+				
+				var onlinePlayerCount = await serverStatusProtocol.GetOnlinePlayerCount(serverPort, CancellationToken);
+				if (onlinePlayerCount == null) {
+					Logger.Warning("Could not detect whether any players are online, starting a new backup.");
+					break;
+				}
+
+				if (onlinePlayerCount > 0) {
+					Logger.Information("Players are online, starting a new backup.");
+					break;
+				}
+
+				if (needsToLogOfflinePlayersMessage) {
+					needsToLogOfflinePlayersMessage = false;
+					Logger.Information("No players are online, waiting for someone to join before starting a new backup.");
+				}
+
+				await Task.Delay(TimeSpan.FromSeconds(10), CancellationToken);
+				
+				Logger.Debug("Waiting for server output before checking for online players again...");
+				await serverOutputWhileWaitingForOnlinePlayers.WaitHandle.WaitOneAsync(CancellationToken);
+			}
+		} finally {
+			process.RemoveOutputListener(ServerOutputListener);
+		}
+	}
+
+	private void ServerOutputListener(object? sender, string line) {
+		if (!serverOutputWhileWaitingForOnlinePlayers.IsSet) {
+			serverOutputWhileWaitingForOnlinePlayers.Set();
+			Logger.Debug("Detected server output, signalling to check for online players again.");
+		}
+	}
+}

Agent/Phantom.Agent.Services/Backups/BackupServerCommandDispatcher.cs

@@ -0,0 +1,80 @@
+using System.Text.RegularExpressions;
+using Phantom.Agent.Minecraft.Command;
+using Phantom.Agent.Minecraft.Instance;
+using Phantom.Utils.Runtime;
+using Serilog;
+
+namespace Phantom.Agent.Services.Backups;
+
+sealed partial class BackupServerCommandDispatcher : IDisposable {
+	[GeneratedRegex(@"^\[(?:.*?)\] \[Server thread/INFO\]: (.*?)$", RegexOptions.NonBacktracking)]
+	private static partial Regex ServerThreadInfoRegex();
+
+	private readonly ILogger logger;
+	private readonly InstanceProcess process;
+	private readonly CancellationToken cancellationToken;
+
+	private readonly TaskCompletionSource automaticSavingDisabled = Tasks.CreateCompletionSource();
+	private readonly TaskCompletionSource savedTheGame = Tasks.CreateCompletionSource();
+	private readonly TaskCompletionSource automaticSavingEnabled = Tasks.CreateCompletionSource();
+
+	public BackupServerCommandDispatcher(ILogger logger, InstanceProcess process, CancellationToken cancellationToken) {
+		this.logger = logger;
+		this.process = process;
+		this.cancellationToken = cancellationToken;
+
+		this.process.AddOutputListener(OnOutput, maxLinesToReadFromHistory: 0);
+	}
+
+	void IDisposable.Dispose() {
+		process.RemoveOutputListener(OnOutput);
+	}
+
+	public async Task DisableAutomaticSaving() {
+		await process.SendCommand(MinecraftCommand.SaveOff, cancellationToken);
+		await automaticSavingDisabled.Task.WaitAsync(cancellationToken);
+	}
+
+	public async Task SaveAllChunks() {
+		// TODO Try if not flushing and waiting a few seconds before flushing reduces lag.
+		await process.SendCommand(MinecraftCommand.SaveAll(flush: true), cancellationToken);
+		await savedTheGame.Task.WaitAsync(cancellationToken);
+	}
+
+	public async Task EnableAutomaticSaving() {
+		await process.SendCommand(MinecraftCommand.SaveOn, cancellationToken);
+		await automaticSavingEnabled.Task.WaitAsync(cancellationToken);
+	}
+
+	private void OnOutput(object? sender, string? line) {
+		if (line == null) {
+			return;
+		}
+
+		var match = ServerThreadInfoRegex().Match(line);
+		if (!match.Success) {
+			return;
+		}
+
+		string info = match.Groups[1].Value;
+
+		if (!automaticSavingDisabled.Task.IsCompleted) {
+			if (info == "Automatic saving is now disabled") {
+				logger.Debug("Detected that automatic saving is disabled.");
+				automaticSavingDisabled.SetResult();
+			}
+		}
+		else if (!savedTheGame.Task.IsCompleted) {
+			if (info == "Saved the game") {
+				logger.Debug("Detected that the game is saved.");
+				savedTheGame.SetResult();
+			}
+		}
+		else if (!automaticSavingEnabled.Task.IsCompleted) {
+			if (info == "Automatic saving is now enabled") {
+				logger.Debug("Detected that automatic saving is enabled.");
+				automaticSavingEnabled.SetResult();
+			}
+		}
+	}
+}

Agent/Phantom.Agent.Services/Instances/Instance.cs

@@ -2,6 +2,7 @@
 using Phantom.Agent.Rpc;
 using Phantom.Agent.Services.Instances.States;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
 using Phantom.Common.Data.Replies;
 using Phantom.Common.Logging;
 using Phantom.Common.Messages.ToServer;
@@ -17,104 +18,125 @@ sealed class Instance : IDisposable {
 		return prefix[..prefix.IndexOf('-')] + "/" + Interlocked.Increment(ref loggerSequenceId);
 	}
 
-	public static async Task<Instance> Create(InstanceConfiguration configuration, BaseLauncher launcher, LaunchServices launchServices, PortManager portManager) {
-		var instance = new Instance(configuration, launcher, launchServices, portManager);
-		await instance.ReportLastStatus();
-		return instance;
-	}
+	private InstanceServices Services { get; }
 	
 	public InstanceConfiguration Configuration { get; private set; }
-	private BaseLauncher Launcher { get; set; }
+	private IServerLauncher Launcher { get; set; }
 
 	private readonly string shortName;
 	private readonly ILogger logger;
 
-	private readonly LaunchServices launchServices;
-	private readonly PortManager portManager;
+	private IInstanceStatus currentStatus;
+	private int statusUpdateCounter;
 	
-	private InstanceStatus currentStatus;
 	private IInstanceState currentState;
 	private readonly SemaphoreSlim stateTransitioningActionSemaphore = new (1, 1);
 
-	private Instance(InstanceConfiguration configuration, BaseLauncher launcher, LaunchServices launchServices, PortManager portManager) {
+	public bool IsRunning => currentState is not InstanceNotRunningState;
+	
+	public event EventHandler? IsRunningChanged; 
+
+	public Instance(InstanceServices services, InstanceConfiguration configuration, IServerLauncher launcher) {
 		this.shortName = GetLoggerName(configuration.InstanceGuid);
 		this.logger = PhantomLogger.Create<Instance>(shortName);
 
+		this.Services = services;
 		this.Configuration = configuration;
 		this.Launcher = launcher;
 		
-		this.launchServices = launchServices;
-		this.portManager = portManager;
 		this.currentState = new InstanceNotRunningState();
-		this.currentStatus = InstanceStatus.IsNotRunning;
+		this.currentStatus = InstanceStatus.NotRunning;
 	}
 
-	private async Task ReportLastStatus() {
-		await ServerMessaging.SendMessage(new ReportInstanceStatusMessage(Configuration.InstanceGuid, currentStatus));
+	private void TryUpdateStatus(string taskName, Func<Task> getUpdateTask) {
+		int myStatusUpdateCounter = Interlocked.Increment(ref statusUpdateCounter);
+		
+		Services.TaskManager.Run(taskName, async () => {
+			if (myStatusUpdateCounter == statusUpdateCounter) {
+				await getUpdateTask();
+			}
+		});
 	}
 
-	private bool TransitionState(IInstanceState newState) {
+	public void ReportLastStatus() {
+		TryUpdateStatus("Report last status of instance " + shortName, async () => {
+			await ServerMessaging.Send(new ReportInstanceStatusMessage(Configuration.InstanceGuid, currentStatus));
+		});
+	}
+
+	private void ReportAndSetStatus(IInstanceStatus status) {
+		TryUpdateStatus("Report status of instance " + shortName + " as " + status.GetType().Name, async () => {
+			currentStatus = status;
+			await ServerMessaging.Send(new ReportInstanceStatusMessage(Configuration.InstanceGuid, status));
+		});
+	}
+
+	private void ReportEvent(IInstanceEvent instanceEvent) {
+		var message = new ReportInstanceEventMessage(Guid.NewGuid(), DateTime.UtcNow, Configuration.InstanceGuid, instanceEvent);
+		Services.TaskManager.Run("Report event for instance " + shortName, async () => await ServerMessaging.Send(message));
+	}
+	
+	private void TransitionState(IInstanceState newState) {
 		if (currentState == newState) {
-			return false;
+			return;
 		}
 
 		if (currentState is IDisposable disposable) {
 			disposable.Dispose();
 		}
 
+		logger.Debug("Transitioning instance state to: {NewState}", newState.GetType().Name);
+		
+		var wasRunning = IsRunning;
 		currentState = newState;
-		return true;
+		currentState.Initialize();
+
+		if (IsRunning != wasRunning) {
+			IsRunningChanged?.Invoke(this, EventArgs.Empty);
+		}
 	}
 
-	public async Task Reconfigure(InstanceConfiguration configuration, BaseLauncher launcher, CancellationToken cancellationToken) {
+	private T TransitionStateAndReturn<T>((IInstanceState State, T Result) newStateAndResult) {
+		TransitionState(newStateAndResult.State);
+		return newStateAndResult.Result;
+	}
+
+	public async Task Reconfigure(InstanceConfiguration configuration, IServerLauncher launcher, CancellationToken cancellationToken) {
 		await stateTransitioningActionSemaphore.WaitAsync(cancellationToken);
 		try {
 			Configuration = configuration;
 			Launcher = launcher;
-			await ReportLastStatus();
 		} finally {
 			stateTransitioningActionSemaphore.Release();
 		}
 	}
 
-	public async Task<LaunchInstanceResult> Launch(CancellationToken cancellationToken) {
-		await stateTransitioningActionSemaphore.WaitAsync(cancellationToken);
+	public async Task<LaunchInstanceResult> Launch(CancellationToken shutdownCancellationToken) {
+		await stateTransitioningActionSemaphore.WaitAsync(shutdownCancellationToken);
 		try {
-			if (TransitionState(currentState.Launch(new InstanceContextImpl(this)))) {
-				return LaunchInstanceResult.LaunchInitiated;
-			}
-
-			return currentState switch {
-				InstanceLaunchingState => LaunchInstanceResult.InstanceAlreadyLaunching,
-				InstanceRunningState   => LaunchInstanceResult.InstanceAlreadyRunning,
-				InstanceStoppingState  => LaunchInstanceResult.InstanceIsStopping,
-				_                      => LaunchInstanceResult.UnknownError
-			};
+			return TransitionStateAndReturn(currentState.Launch(new InstanceContextImpl(this, shutdownCancellationToken)));
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while launching instance.");
+			return LaunchInstanceResult.UnknownError;
 		} finally {
 			stateTransitioningActionSemaphore.Release();
 		}
 	}
 
-	public async Task<StopInstanceResult> Stop() {
+	public async Task<StopInstanceResult> Stop(MinecraftStopStrategy stopStrategy) {
 		await stateTransitioningActionSemaphore.WaitAsync();
 		try {
-			if (TransitionState(currentState.Stop())) {
-				return StopInstanceResult.StopInitiated;
-			}
-
-			return currentState switch {
-				InstanceNotRunningState => StopInstanceResult.InstanceAlreadyStopped,
-				InstanceLaunchingState  => StopInstanceResult.StopInitiated,
-				InstanceStoppingState   => StopInstanceResult.InstanceAlreadyStopping,
-				_                       => StopInstanceResult.UnknownError
-			};
+			return TransitionStateAndReturn(currentState.Stop(stopStrategy));
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while stopping instance.");
+			return StopInstanceResult.UnknownError;
 		} finally {
 			stateTransitioningActionSemaphore.Release();
 		}
 	}
 
 	public async Task StopAndWait(TimeSpan waitTime) {
-		await Stop();
+		await Stop(MinecraftStopStrategy.Instant);
 
 		using var waitTokenSource = new CancellationTokenSource(waitTime);
 		var waitToken = waitTokenSource.Token;
@@ -130,32 +152,47 @@ sealed class Instance : IDisposable {
 
 	private sealed class InstanceContextImpl : InstanceContext {
 		private readonly Instance instance;
-		private int statusUpdateCounter;
+		private readonly CancellationToken shutdownCancellationToken;
 		
-		public InstanceContextImpl(Instance instance) : base(instance.Configuration, instance.Launcher) {
+		public InstanceContextImpl(Instance instance, CancellationToken shutdownCancellationToken) : base(instance.Services, instance.Configuration, instance.Launcher) {
 			this.instance = instance;
+			this.shutdownCancellationToken = shutdownCancellationToken;
 		}
 
-		public override LaunchServices LaunchServices => instance.launchServices;
-		public override PortManager PortManager => instance.portManager;
 		public override ILogger Logger => instance.logger;
 		public override string ShortName => instance.shortName;
 
-		public override void ReportStatus(InstanceStatus newStatus) {
-			int myStatusUpdateCounter = Interlocked.Increment(ref statusUpdateCounter);
-			
-			Task.Run(async () => {
-				if (myStatusUpdateCounter == statusUpdateCounter) {
-					instance.currentStatus = newStatus;
-					await ServerMessaging.SendMessage(new ReportInstanceStatusMessage(Configuration.InstanceGuid, newStatus));
-				}
-			});
+		public override void SetStatus(IInstanceStatus newStatus) {
+			instance.ReportAndSetStatus(newStatus);
 		}
 
-		public override void TransitionState(Func<IInstanceState> newState) {
-			instance.stateTransitioningActionSemaphore.Wait();
+		public override void ReportEvent(IInstanceEvent instanceEvent) {
+			instance.ReportEvent(instanceEvent);
+		}
+
+		public override void TransitionState(Func<(IInstanceState, IInstanceStatus?)> newStateAndStatus) {
+			instance.stateTransitioningActionSemaphore.Wait(CancellationToken.None);
 			try {
-				instance.TransitionState(newState());
+				var (state, status) = newStateAndStatus();
+				
+				if (!instance.IsRunning) {
+					// Only InstanceSessionManager is allowed to transition an instance out of a non-running state.
+					instance.logger.Debug("Cancelled state transition to {State} because instance is not running.", state.GetType().Name);
+					return;
+				}
+				
+				if (state is not InstanceNotRunningState && shutdownCancellationToken.IsCancellationRequested) {
+					instance.logger.Debug("Cancelled state transition to {State} due to Agent shutdown.", state.GetType().Name);
+					return;
+				}
+
+				if (status != null) {
+					SetStatus(status);
+				}
+
+				instance.TransitionState(state);
+			} catch (Exception e) {
+				instance.logger.Error(e, "Caught exception during state transition.");
 			} finally {
 				instance.stateTransitioningActionSemaphore.Release();
 			}
@@ -163,10 +200,10 @@ sealed class Instance : IDisposable {
 	}
 
 	public void Dispose() {
+		stateTransitioningActionSemaphore.Dispose();
+		
 		if (currentState is IDisposable disposable) {
 			disposable.Dispose();
 		}
-
-		stateTransitioningActionSemaphore.Dispose();
 	}
 }

Agent/Phantom.Agent.Services/Instances/InstanceContext.cs

@@ -6,23 +6,30 @@ using Serilog;
 namespace Phantom.Agent.Services.Instances;
 
 abstract class InstanceContext {
+	public InstanceServices Services { get; }
 	public InstanceConfiguration Configuration { get; }
-	public BaseLauncher Launcher { get; }
+	public IServerLauncher Launcher { get; }
 	
-	public abstract LaunchServices LaunchServices { get; }
-	public abstract PortManager PortManager { get; }
 	public abstract ILogger Logger { get; }
 	public abstract string ShortName { get; }
 
-	protected InstanceContext(InstanceConfiguration configuration, BaseLauncher launcher) {
+	protected InstanceContext(InstanceServices services, InstanceConfiguration configuration, IServerLauncher launcher) {
+		Services = services;
 		Configuration = configuration;
 		Launcher = launcher;
 	}
 
-	public abstract void ReportStatus(InstanceStatus newStatus);
-	public abstract void TransitionState(Func<IInstanceState> newState);
+	public abstract void SetStatus(IInstanceStatus newStatus);
 
-	public void TransitionState(IInstanceState newState) {
-		TransitionState(() => newState);
+	public void SetLaunchFailedStatusAndReportEvent(InstanceLaunchFailReason reason) {
+		SetStatus(InstanceStatus.Failed(reason));
+		ReportEvent(new InstanceLaunchFailedEvent(reason));
+	}
+
+	public abstract void ReportEvent(IInstanceEvent instanceEvent);
+	public abstract void TransitionState(Func<(IInstanceState, IInstanceStatus?)> newStateAndStatus);
+
+	public void TransitionState(IInstanceState newState, IInstanceStatus? newStatus = null) {
+		TransitionState(() => (newState, newStatus));
 	}
 }

Agent/Phantom.Agent.Services/Instances/InstanceLogSender.cs

@@ -0,0 +1,71 @@
+using System.Collections.Immutable;
+using Phantom.Agent.Rpc;
+using Phantom.Common.Logging;
+using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.Collections;
+using Phantom.Utils.Runtime;
+
+namespace Phantom.Agent.Services.Instances;
+
+sealed class InstanceLogSender : CancellableBackgroundTask {
+	private static readonly TimeSpan SendDelay = TimeSpan.FromMilliseconds(200);
+
+	private readonly Guid instanceGuid;
+
+	private readonly SemaphoreSlim semaphore = new (1, 1);
+	private readonly RingBuffer<string> buffer = new (1000);
+
+	public InstanceLogSender(TaskManager taskManager, Guid instanceGuid, string loggerName) : base(PhantomLogger.Create<InstanceLogSender>(loggerName), taskManager, "Instance log sender for " + loggerName) {
+		this.instanceGuid = instanceGuid;
+	}
+	
+	protected override async Task RunTask() {
+		try {
+			while (!CancellationToken.IsCancellationRequested) {
+				await SendOutputToServer(await DequeueOrThrow());
+				await Task.Delay(SendDelay, CancellationToken);
+			}
+		} catch (OperationCanceledException) {
+			// Ignore.
+		}
+
+		// Flush remaining lines.
+		await SendOutputToServer(DequeueWithoutSemaphore());
+	}
+
+	private async Task SendOutputToServer(ImmutableArray<string> lines) {
+		if (!lines.IsEmpty) {
+			await ServerMessaging.Send(new InstanceOutputMessage(instanceGuid, lines));
+		}
+	}
+
+	private ImmutableArray<string> DequeueWithoutSemaphore() {
+		ImmutableArray<string> lines = buffer.Count > 0 ? buffer.EnumerateLast(uint.MaxValue).ToImmutableArray() : ImmutableArray<string>.Empty;
+		buffer.Clear();
+		return lines;
+	}
+
+	private async Task<ImmutableArray<string>> DequeueOrThrow() {
+		await semaphore.WaitAsync(CancellationToken);
+
+		try {
+			return DequeueWithoutSemaphore();
+		} finally {
+			semaphore.Release();
+		}
+	}
+
+	public void Enqueue(string line) {
+		try {
+			semaphore.Wait(CancellationToken);
+		} catch (Exception) {
+			return;
+		}
+
+		try {
+			buffer.Add(line);
+		} finally {
+			semaphore.Release();
+		}
+	}
+}

Agent/Phantom.Agent.Services/Instances/InstanceLogSenderThread.cs

@@ -1,84 +0,0 @@
-using System.Collections.Immutable;
-using System.Diagnostics.CodeAnalysis;
-using Phantom.Agent.Rpc;
-using Phantom.Common.Logging;
-using Phantom.Common.Messages.ToServer;
-using Phantom.Utils.Collections;
-using Serilog;
-
-namespace Phantom.Agent.Services.Instances; 
-
-sealed class InstanceLogSenderThread {
-	private readonly Guid instanceGuid;
-	private readonly ILogger logger;
-	private readonly CancellationTokenSource cancellationTokenSource;
-	private readonly CancellationToken cancellationToken;
-	
-	private readonly SemaphoreSlim semaphore = new (1, 1);
-	private readonly RingBuffer<string> buffer = new (1000);
-	
-	public InstanceLogSenderThread(Guid instanceGuid, string name) {
-		this.instanceGuid = instanceGuid;
-		this.logger = PhantomLogger.Create<InstanceLogSenderThread>(name);
-		this.cancellationTokenSource = new CancellationTokenSource();
-		this.cancellationToken = cancellationTokenSource.Token;
-		
-		var thread = new Thread(Run) {
-			IsBackground = true,
-			Name = "Instance Log Sender (" + name + ")"
-		};
-		
-		thread.Start();
-	}
-
-	[SuppressMessage("ReSharper", "LocalVariableHidesMember")]
-	private async void Run() {
-		logger.Verbose("Thread started.");
-		
-		try {
-			while (!cancellationToken.IsCancellationRequested) {
-				await semaphore.WaitAsync(cancellationToken);
-
-				ImmutableArray<string> lines;
-				
-				try {
-					lines = buffer.Count > 0 ? buffer.EnumerateLast(uint.MaxValue).ToImmutableArray() : ImmutableArray<string>.Empty;
-					buffer.Clear();
-				} finally {
-					semaphore.Release();
-				}
-
-				if (lines.Length > 0) {
-					await ServerMessaging.SendMessage(new InstanceOutputMessage(instanceGuid, lines));
-				}
-
-				await Task.Delay(TimeSpan.FromMilliseconds(200), cancellationToken);
-			}
-		} catch (OperationCanceledException) {
-			// Ignore.
-		} catch (Exception e) {
-			logger.Error(e, "Caught exception in thread.");
-		} finally {
-			cancellationTokenSource.Dispose();
-			logger.Verbose("Thread stopped.");
-		}
-	}
-
-	public void Enqueue(string line) {
-		try {
-			semaphore.Wait(cancellationToken);
-		} catch (Exception) {
-			return;
-		}
-
-		try {
-			buffer.Add(line);
-		} finally {
-			semaphore.Release();
-		}
-	}
-
-	public void Cancel() {
-		cancellationTokenSource.Cancel();
-	}
-}

Agent/Phantom.Agent.Services/Instances/InstanceServices.cs

@@ -0,0 +1,7 @@
+using Phantom.Agent.Minecraft.Launcher;
+using Phantom.Agent.Services.Backups;
+using Phantom.Utils.Runtime;
+
+namespace Phantom.Agent.Services.Instances; 
+
+sealed record InstanceServices(TaskManager TaskManager, PortManager PortManager, BackupManager BackupManager, LaunchServices LaunchServices);

Agent/Phantom.Agent.Services/Instances/InstanceSessionManager.cs

@@ -1,14 +1,22 @@
-using Phantom.Agent.Minecraft.Instance;
+using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
+using Phantom.Agent.Minecraft.Instance;
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Launcher;
 using Phantom.Agent.Minecraft.Launcher.Types;
 using Phantom.Agent.Minecraft.Properties;
 using Phantom.Agent.Minecraft.Server;
+using Phantom.Agent.Rpc;
+using Phantom.Agent.Services.Backups;
 using Phantom.Common.Data;
 using Phantom.Common.Data.Agent;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
 using Phantom.Common.Data.Replies;
 using Phantom.Common.Logging;
+using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.IO;
+using Phantom.Utils.Runtime;
 using Serilog;
 
 namespace Phantom.Agent.Services.Instances;
@@ -19,41 +27,55 @@ sealed class InstanceSessionManager : IDisposable {
 	private readonly AgentInfo agentInfo;
 	private readonly string basePath;
 
-	private readonly LaunchServices launchServices;
-	private readonly PortManager portManager;
+	private readonly InstanceServices instanceServices;
 	private readonly Dictionary<Guid, Instance> instances = new ();
 
 	private readonly CancellationTokenSource shutdownCancellationTokenSource = new ();
 	private readonly CancellationToken shutdownCancellationToken;
 	private readonly SemaphoreSlim semaphore = new (1, 1);
 
-	public InstanceSessionManager(AgentInfo agentInfo, AgentFolders agentFolders, JavaRuntimeRepository javaRuntimeRepository) {
+	public InstanceSessionManager(AgentInfo agentInfo, AgentFolders agentFolders, JavaRuntimeRepository javaRuntimeRepository, TaskManager taskManager, BackupManager backupManager) {
 		this.agentInfo = agentInfo;
 		this.basePath = agentFolders.InstancesFolderPath;
-		this.launchServices = new LaunchServices(new MinecraftServerExecutables(agentFolders.ServerExecutableFolderPath), javaRuntimeRepository);
-		this.portManager = new PortManager(agentInfo.AllowedServerPorts, agentInfo.AllowedRconPorts);
 		this.shutdownCancellationToken = shutdownCancellationTokenSource.Token;
+		
+		var minecraftServerExecutables = new MinecraftServerExecutables(agentFolders.ServerExecutableFolderPath);
+		var launchServices = new LaunchServices(minecraftServerExecutables, javaRuntimeRepository);
+		var portManager = new PortManager(agentInfo.AllowedServerPorts, agentInfo.AllowedRconPorts);
+		
+		this.instanceServices = new InstanceServices(taskManager, portManager, backupManager, launchServices);
 	}
 
-	public async Task<ConfigureInstanceResult> Configure(InstanceConfiguration configuration) {
+	private async Task<InstanceActionResult<T>> AcquireSemaphoreAndRun<T>(Func<Task<InstanceActionResult<T>>> func) {
 		try {
 			await semaphore.WaitAsync(shutdownCancellationToken);
+			try {
+				return await func();
+			} finally {
+				semaphore.Release();
+			}
 		} catch (OperationCanceledException) {
-			return ConfigureInstanceResult.AgentShuttingDown;
+			return InstanceActionResult.General<T>(InstanceActionGeneralResult.AgentShuttingDown);
 		}
+	}
 
-		var instanceGuid = configuration.InstanceGuid;
-
-		try {
-			var otherInstances = instances.Values.Where(inst => inst.Configuration.InstanceGuid != instanceGuid).ToArray();
-			if (otherInstances.Length + 1 > agentInfo.MaxInstances) {
-				return ConfigureInstanceResult.InstanceLimitExceeded;
+	[SuppressMessage("ReSharper", "ConvertIfStatementToReturnStatement")]
+	private Task<InstanceActionResult<T>> AcquireSemaphoreAndRunWithInstance<T>(Guid instanceGuid, Func<Instance, Task<T>> func) {
+		return AcquireSemaphoreAndRun(async () => {
+			if (instances.TryGetValue(instanceGuid, out var instance)) {
+				return InstanceActionResult.Concrete(await func(instance));
 			}
-
-			var availableMemory = agentInfo.MaxMemory - otherInstances.Aggregate(RamAllocationUnits.Zero, static (total, instance) => total + instance.Configuration.MemoryAllocation);
-			if (availableMemory < configuration.MemoryAllocation) {
-				return ConfigureInstanceResult.MemoryLimitExceeded;
+			else {
+				return InstanceActionResult.General<T>(InstanceActionGeneralResult.InstanceDoesNotExist);
 			}
+		});
+	}
+
+	public async Task<InstanceActionResult<ConfigureInstanceResult>> Configure(InstanceConfiguration configuration, InstanceLaunchProperties launchProperties, bool launchNow, bool alwaysReportStatus) {
+		return await AcquireSemaphoreAndRun(async () => {
+			var instanceGuid = configuration.InstanceGuid;
+			var instanceFolder = Path.Combine(basePath, instanceGuid.ToString());
+			Directories.Create(instanceFolder, Chmod.URWX_GRX);
 			
 			var heapMegabytes = configuration.MemoryAllocation.InMegabytes;
 			var jvmProperties = new JvmProperties(
@@ -61,112 +83,122 @@ sealed class InstanceSessionManager : IDisposable {
 				MaximumHeapMegabytes: heapMegabytes
 			);
 
-			var instanceFolder = Path.Combine(basePath, instanceGuid.ToString());
-			Directory.CreateDirectory(instanceFolder);
-
 			var properties = new InstanceProperties(
+				instanceGuid,
 				configuration.JavaRuntimeGuid,
 				jvmProperties,
+				configuration.JvmArguments,
 				instanceFolder,
 				configuration.MinecraftVersion,
-				new ServerProperties(configuration.ServerPort, configuration.RconPort)
+				new ServerProperties(configuration.ServerPort, configuration.RconPort),
+				launchProperties
 			);
 
-			BaseLauncher launcher = new VanillaLauncher(properties);
+			IServerLauncher launcher = configuration.MinecraftServerKind switch {
+				MinecraftServerKind.Vanilla => new VanillaLauncher(properties),
+				MinecraftServerKind.Fabric  => new FabricLauncher(properties),
+				_                           => InvalidLauncher.Instance
+			};
 
 			if (instances.TryGetValue(instanceGuid, out var instance)) {
 				await instance.Reconfigure(configuration, launcher, shutdownCancellationToken);
 				Logger.Information("Reconfigured instance \"{Name}\" (GUID {Guid}).", configuration.InstanceName, configuration.InstanceGuid);
+				
+				if (alwaysReportStatus) {
+					instance.ReportLastStatus();
+				}
 			}
 			else {
-				instances[instanceGuid] = instance = await Instance.Create(configuration, launcher, launchServices, portManager);
+				instances[instanceGuid] = instance = new Instance(instanceServices, configuration, launcher);
 				Logger.Information("Created instance \"{Name}\" (GUID {Guid}).", configuration.InstanceName, configuration.InstanceGuid);
+				
+				instance.ReportLastStatus();
+				instance.IsRunningChanged += OnInstanceIsRunningChanged;
 			}
 
-			if (configuration.LaunchAutomatically) {
-				await instance.Launch(shutdownCancellationToken);
+			if (launchNow) {
+				await LaunchInternal(instance);
 			}
 
-			return ConfigureInstanceResult.Success;
-		} finally {
-			semaphore.Release();
+			return InstanceActionResult.Concrete(ConfigureInstanceResult.Success);
+		});
+	}
+
+	private ImmutableArray<Instance> GetRunningInstancesInternal() {
+		return instances.Values.Where(static instance => instance.IsRunning).ToImmutableArray();
+	}
+
+	private void OnInstanceIsRunningChanged(object? sender, EventArgs e) {
+		instanceServices.TaskManager.Run("Handle instance running state changed event", RefreshAgentStatus);
+	}
+
+	public async Task RefreshAgentStatus() {
+		try {
+			await semaphore.WaitAsync(shutdownCancellationToken);
+			try {
+				var runningInstances = GetRunningInstancesInternal();
+				var runningInstanceCount = runningInstances.Length;
+				var runningInstanceMemory = runningInstances.Aggregate(RamAllocationUnits.Zero, static (total, instance) => total + instance.Configuration.MemoryAllocation);
+				await ServerMessaging.Send(new ReportAgentStatusMessage(runningInstanceCount, runningInstanceMemory));
+			} finally {
+				semaphore.Release();
+			}
+		} catch (OperationCanceledException) {
+			// ignore
 		}
 	}
 
-	public async Task<LaunchInstanceResult> Launch(Guid instanceGuid) {
-		try {
-			await semaphore.WaitAsync(shutdownCancellationToken);
-		} catch (OperationCanceledException) {
-			return LaunchInstanceResult.AgentShuttingDown;
-		}
-
-		try {
-			if (!instances.TryGetValue(instanceGuid, out var instance)) {
-				return LaunchInstanceResult.InstanceDoesNotExist;
-			}
-			else {
-				return await instance.Launch(shutdownCancellationToken);
-			}
-		} finally {
-			semaphore.Release();
-		}
+	public Task<InstanceActionResult<LaunchInstanceResult>> Launch(Guid instanceGuid) {
+		return AcquireSemaphoreAndRunWithInstance(instanceGuid, LaunchInternal);
 	}
 
-	public async Task<StopInstanceResult> Stop(Guid instanceGuid) {
-		try {
-			await semaphore.WaitAsync(shutdownCancellationToken);
-		} catch (OperationCanceledException) {
-			return StopInstanceResult.AgentShuttingDown;
+	private async Task<LaunchInstanceResult> LaunchInternal(Instance instance) {
+		var runningInstances = GetRunningInstancesInternal();
+		if (runningInstances.Length + 1 > agentInfo.MaxInstances) {
+			return LaunchInstanceResult.InstanceLimitExceeded;
 		}
 
-		try {
-			if (!instances.TryGetValue(instanceGuid, out var instance)) {
-				return StopInstanceResult.InstanceDoesNotExist;
-			}
-			else {
-				return await instance.Stop();
-			}
-		} finally {
-			semaphore.Release();
+		var availableMemory = agentInfo.MaxMemory - runningInstances.Aggregate(RamAllocationUnits.Zero, static (total, instance) => total + instance.Configuration.MemoryAllocation);
+		if (availableMemory < instance.Configuration.MemoryAllocation) {
+			return LaunchInstanceResult.MemoryLimitExceeded;
 		}
+
+		return await instance.Launch(shutdownCancellationToken);
 	}
 
-	public async Task<SendCommandToInstanceResult> SendCommand(Guid instanceGuid, string command) {
-		try {
-			await semaphore.WaitAsync(shutdownCancellationToken);
-		} catch (OperationCanceledException) {
-			return SendCommandToInstanceResult.AgentShuttingDown;
-		}
+	public Task<InstanceActionResult<StopInstanceResult>> Stop(Guid instanceGuid, MinecraftStopStrategy stopStrategy) {
+		return AcquireSemaphoreAndRunWithInstance(instanceGuid, instance => instance.Stop(stopStrategy));
+	}
 
-		try {
-			if (!instances.TryGetValue(instanceGuid, out var instance)) {
-				return SendCommandToInstanceResult.InstanceDoesNotExist;
-			}
-
-			if (!await instance.SendCommand(command, shutdownCancellationToken)) {
-				return SendCommandToInstanceResult.UnknownError;
-			}
-
-			return SendCommandToInstanceResult.Success;
-		} finally {
-			semaphore.Release();
-		}
+	public Task<InstanceActionResult<SendCommandToInstanceResult>> SendCommand(Guid instanceGuid, string command) {
+		return AcquireSemaphoreAndRunWithInstance(instanceGuid, async instance => await instance.SendCommand(command, shutdownCancellationToken) ? SendCommandToInstanceResult.Success : SendCommandToInstanceResult.UnknownError);
 	}
 
 	public async Task StopAll() {
 		shutdownCancellationTokenSource.Cancel();
 		
+		Logger.Information("Stopping all instances...");
+
 		await semaphore.WaitAsync(CancellationToken.None);
 		try {
 			await Task.WhenAll(instances.Values.Select(static instance => instance.StopAndWait(TimeSpan.FromSeconds(30))));
-			instances.Clear();
+			DisposeAllInstances();
 		} finally {
 			semaphore.Release();
 		}
 	}
 
 	public void Dispose() {
+		DisposeAllInstances();
 		shutdownCancellationTokenSource.Dispose();
 		semaphore.Dispose();
 	}
+
+	private void DisposeAllInstances() {
+		foreach (var (_, instance) in instances) {
+			instance.Dispose();
+		}
+
+		instances.Clear();
+	}
 }

Agent/Phantom.Agent.Services/Instances/PortManager.cs

@@ -14,17 +14,28 @@ sealed class PortManager {
 	}
 
 	public Result Reserve(InstanceConfiguration configuration) {
+		var serverPort = configuration.ServerPort;
+		var rconPort = configuration.RconPort;
+		
+		if (!allowedServerPorts.Contains(serverPort)) {
+			return Result.ServerPortNotAllowed;
+		}
+
+		if (!allowedRconPorts.Contains(rconPort)) {
+			return Result.RconPortNotAllowed;
+		}
+		
 		lock (usedPorts) {
-			if (usedPorts.Contains(configuration.ServerPort)) {
+			if (usedPorts.Contains(serverPort)) {
 				return Result.ServerPortAlreadyInUse;
 			}
 
-			if (usedPorts.Contains(configuration.RconPort)) {
+			if (usedPorts.Contains(rconPort)) {
 				return Result.RconPortAlreadyInUse;
 			}
 
-			usedPorts.Add(configuration.ServerPort);
-			usedPorts.Add(configuration.RconPort);
+			usedPorts.Add(serverPort);
+			usedPorts.Add(rconPort);
 		}
 
 		return Result.Success;
@@ -42,6 +53,6 @@ sealed class PortManager {
 		ServerPortNotAllowed,
 		ServerPortAlreadyInUse,
 		RconPortNotAllowed,
-		RconPortAlreadyInUse,
+		RconPortAlreadyInUse
 	}
 }

Agent/Phantom.Agent.Services/Instances/Sessions/InstanceSession.cs

@@ -0,0 +1,28 @@
+using Phantom.Agent.Minecraft.Instance;
+
+namespace Phantom.Agent.Services.Instances.Sessions; 
+
+sealed class InstanceSession : IDisposable {
+	private readonly InstanceProcess process;
+	private readonly InstanceContext context;
+	private readonly InstanceLogSender logSender;
+
+	public InstanceSession(InstanceProcess process, InstanceContext context) {
+		this.process = process;
+		this.context = context;
+		this.logSender = new InstanceLogSender(context.Services.TaskManager, context.Configuration.InstanceGuid, context.ShortName);
+		
+		this.process.AddOutputListener(SessionOutput);
+	}
+	
+	private void SessionOutput(object? sender, string line) {
+		context.Logger.Debug("[Server] {Line}", line);
+		logSender.Enqueue(line);
+	}
+	
+	public void Dispose() {
+		logSender.Stop();
+		process.Dispose();
+		context.Services.PortManager.Release(context.Configuration);
+	}
+}

Agent/Phantom.Agent.Services/Instances/States/IInstanceState.cs

@@ -1,7 +1,11 @@
-namespace Phantom.Agent.Services.Instances.States; 
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
+
+namespace Phantom.Agent.Services.Instances.States; 
 
 interface IInstanceState {
-	IInstanceState Launch(InstanceContext context);
-	IInstanceState Stop();
+	void Initialize();
+	(IInstanceState, LaunchInstanceResult) Launch(InstanceContext context);
+	(IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy);
 	Task<bool> SendCommand(string command, CancellationToken cancellationToken);
 }

Agent/Phantom.Agent.Services/Instances/States/InstanceLaunchingState.cs

@@ -1,7 +1,10 @@
 using Phantom.Agent.Minecraft.Instance;
 using Phantom.Agent.Minecraft.Launcher;
 using Phantom.Agent.Minecraft.Server;
+using Phantom.Agent.Services.Instances.Sessions;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Agent.Services.Instances.States;
 
@@ -12,15 +15,17 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 
 	public InstanceLaunchingState(InstanceContext context) {
 		this.context = context;
-		this.context.Logger.Information("Session starting...");
-		this.context.ReportStatus(InstanceStatus.IsLaunching);
+	}
 
-		var launchTask = Task.Run(DoLaunch);
+	public void Initialize() {
+		context.Logger.Information("Session starting...");
+
+		var launchTask = context.Services.TaskManager.Run("Launch procedure for instance " + context.ShortName, DoLaunch);
 		launchTask.ContinueWith(OnLaunchSuccess, CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, TaskScheduler.Default);
 		launchTask.ContinueWith(OnLaunchFailure, CancellationToken.None, TaskContinuationOptions.NotOnRanToCompletion, TaskScheduler.Default);
 	}
 
-	private async Task<InstanceSession> DoLaunch() {
+	private async Task<InstanceProcess> DoLaunch() {
 		var cancellationToken = cancellationTokenSource.Token;
 		cancellationToken.ThrowIfCancellationRequested();
 
@@ -29,49 +34,67 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 
 			if (lastDownloadProgress != progress) {
 				lastDownloadProgress = progress;
-				context.ReportStatus(new InstanceStatus.Downloading(progress));
+				context.SetStatus(InstanceStatus.Downloading(progress));
 			}
 		}
 
-		var launchResult = await context.Launcher.Launch(context.LaunchServices, OnDownloadProgress, cancellationToken);
-		if (launchResult is LaunchResult.CouldNotDownloadMinecraftServer) {
+		var launchResult = await context.Launcher.Launch(context.Logger, context.Services.LaunchServices, OnDownloadProgress, cancellationToken);
+		if (launchResult is LaunchResult.InvalidJavaRuntime) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.JavaRuntimeNotFound, "Session failed to launch, invalid Java runtime.");
+		}
+		else if (launchResult is LaunchResult.InvalidJvmArguments) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.InvalidJvmArguments, "Session failed to launch, invalid JVM arguments.");
+		}
+		else if (launchResult is LaunchResult.CouldNotDownloadMinecraftServer) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotDownloadMinecraftServer, "Session failed to launch, could not download Minecraft server.");
 		}
-		else if (launchResult is LaunchResult.InvalidJavaRuntime) {
-			throw new LaunchFailureException(InstanceLaunchFailReason.JavaRuntimeNotFound, "Session failed to launch, invalid Java runtime.");
+		else if (launchResult is LaunchResult.CouldNotPrepareMinecraftServerLauncher) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotPrepareMinecraftServerLauncher, "Session failed to launch, could not prepare Minecraft server launcher.");
+		}
+		else if (launchResult is LaunchResult.CouldNotConfigureMinecraftServer) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotConfigureMinecraftServer, "Session failed to launch, could not configure Minecraft server.");
+		}
+		else if (launchResult is LaunchResult.CouldNotStartMinecraftServer) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotStartMinecraftServer, "Session failed to launch, could not start Minecraft server.");
 		}
 
 		if (launchResult is not LaunchResult.Success launchSuccess) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.UnknownError, "Session failed to launch.");
 		}
 
-		context.ReportStatus(InstanceStatus.IsLaunching);
-		return launchSuccess.Session;
+		context.SetStatus(InstanceStatus.Launching);
+		return launchSuccess.Process;
 	}
 
-	private void OnLaunchSuccess(Task<InstanceSession> task) {
+	private void OnLaunchSuccess(Task<InstanceProcess> task) {
 		context.TransitionState(() => {
+			context.ReportEvent(InstanceEvent.LaunchSucceded);
+			
+			var process = task.Result;
+			var session = new InstanceSession(process, context);
+			
 			if (cancellationTokenSource.IsCancellationRequested) {
-				context.PortManager.Release(context.Configuration);
-				context.ReportStatus(InstanceStatus.IsNotRunning);
-				return new InstanceNotRunningState();
+				return (new InstanceStoppingState(context, process, session), InstanceStatus.Stopping);
 			}
 			else {
-				return new InstanceRunningState(context, task.Result);
+				return (new InstanceRunningState(context, process, session), null);
 			}
 		});
 	}
 
 	private void OnLaunchFailure(Task task) {
-		if (task.Exception is { InnerException: LaunchFailureException e }) {
-			context.Logger.Error(e.LogMessage);
-			context.ReportStatus(new InstanceStatus.Failed(e.Reason));
-		}
-		else {
-			context.ReportStatus(new InstanceStatus.Failed(InstanceLaunchFailReason.UnknownError));
+		if (task.IsFaulted) {
+			if (task.Exception is { InnerException: LaunchFailureException e }) {
+				context.Logger.Error(e.LogMessage);
+				context.SetLaunchFailedStatusAndReportEvent(e.Reason);
+			}
+			else {
+				context.Logger.Error(task.Exception, "Caught exception while launching instance.");
+				context.SetLaunchFailedStatusAndReportEvent(InstanceLaunchFailReason.UnknownError);
+			}
 		}
 
-		context.PortManager.Release(context.Configuration);
+		context.Services.PortManager.Release(context.Configuration);
 		context.TransitionState(new InstanceNotRunningState());
 	}
 
@@ -85,13 +108,13 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 		}
 	}
 
-	public IInstanceState Launch(InstanceContext context) {
-		return this;
+	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
+		return (this, LaunchInstanceResult.InstanceAlreadyLaunching);
 	}
 
-	public IInstanceState Stop() {
+	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
 		cancellationTokenSource.Cancel();
-		return this;
+		return (this, StopInstanceResult.StopInitiated);
 	}
 
 	public Task<bool> SendCommand(string command, CancellationToken cancellationToken) {

Agent/Phantom.Agent.Services/Instances/States/InstanceNotRunningState.cs

@@ -1,10 +1,14 @@
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Agent.Services.Instances.States; 
 
 sealed class InstanceNotRunningState : IInstanceState {
-	public IInstanceState Launch(InstanceContext context) {
-		InstanceLaunchFailReason? failReason = context.PortManager.Reserve(context.Configuration) switch {
+	public void Initialize() {}
+
+	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
+		InstanceLaunchFailReason? failReason = context.Services.PortManager.Reserve(context.Configuration) switch {
 			PortManager.Result.ServerPortNotAllowed   => InstanceLaunchFailReason.ServerPortNotAllowed,
 			PortManager.Result.ServerPortAlreadyInUse => InstanceLaunchFailReason.ServerPortAlreadyInUse,
 			PortManager.Result.RconPortNotAllowed     => InstanceLaunchFailReason.RconPortNotAllowed,
@@ -12,16 +16,17 @@ sealed class InstanceNotRunningState : IInstanceState {
 			_                                         => null
 		};
 
-		if (failReason != null) {
-			context.ReportStatus(new InstanceStatus.Failed(failReason.Value));
-			return this;
+		if (failReason is {} reason) {
+			context.SetLaunchFailedStatusAndReportEvent(reason);
+			return (this, LaunchInstanceResult.LaunchInitiated);
 		}
 		
-		return new InstanceLaunchingState(context);
+		context.SetStatus(InstanceStatus.Launching);
+		return (new InstanceLaunchingState(context), LaunchInstanceResult.LaunchInitiated);
 	}
 
-	public IInstanceState Stop() {
-		return this;
+	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
+		return (this, StopInstanceResult.InstanceAlreadyStopped);
 	}
 
 	public Task<bool> SendCommand(string command, CancellationToken cancellationToken) {

Agent/Phantom.Agent.Services/Instances/States/InstanceRunningState.cs

@@ -1,62 +1,133 @@
-using Phantom.Agent.Minecraft.Instance;
+using Phantom.Agent.Minecraft.Command;
+using Phantom.Agent.Minecraft.Instance;
+using Phantom.Agent.Services.Backups;
+using Phantom.Agent.Services.Instances.Sessions;
+using Phantom.Common.Data.Backups;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Agent.Services.Instances.States;
 
 sealed class InstanceRunningState : IInstanceState {
 	private readonly InstanceContext context;
-	private readonly InstanceSession session;
-	private readonly InstanceLogSenderThread logSenderThread;
-	private readonly SessionObjects sessionObjects;
+	private readonly InstanceProcess process;
+	private readonly BackupScheduler backupScheduler;
+	private readonly RunningSessionDisposer runningSessionDisposer;
 	
-	public InstanceRunningState(InstanceContext context, InstanceSession session) {
+	private readonly CancellationTokenSource delayedStopCancellationTokenSource = new ();
+	private bool stateOwnsDelayedStopCancellationTokenSource = true;
+	private bool isStopping;
+
+	public InstanceRunningState(InstanceContext context, InstanceProcess process, InstanceSession session) {
 		this.context = context;
-		this.session = session;
-		this.logSenderThread = new InstanceLogSenderThread(context.Configuration.InstanceGuid, context.ShortName);
-		this.sessionObjects = new SessionObjects(context, session, logSenderThread);
+		this.process = process;
+		this.backupScheduler = new BackupScheduler(context.Services.TaskManager, context.Services.BackupManager, process, context.Configuration.ServerPort, context.ShortName);
+		this.backupScheduler.BackupCompleted += OnScheduledBackupCompleted;
+		this.runningSessionDisposer = new RunningSessionDisposer(this, session);
+	}
 
-		this.session.AddOutputListener(SessionOutput);
-		this.session.SessionEnded += SessionEnded;
+	public void Initialize() {
+		process.Ended += ProcessEnded;
 		
-		if (session.HasEnded) {
-			if (sessionObjects.Dispose()) {
+		if (process.HasEnded) {
+			if (runningSessionDisposer.Dispose()) {
 				context.Logger.Warning("Session ended immediately after it was started.");
-				context.ReportStatus(new InstanceStatus.Failed(InstanceLaunchFailReason.UnknownError));
-				Task.Run(() => context.TransitionState(new InstanceNotRunningState()));
+				context.ReportEvent(InstanceEvent.Stopped);
+				context.Services.TaskManager.Run("Transition state of instance " + context.ShortName + " to not running", () => context.TransitionState(new InstanceNotRunningState(), InstanceStatus.Failed(InstanceLaunchFailReason.UnknownError)));
 			}
 		}
 		else {
-			context.ReportStatus(InstanceStatus.IsRunning);
+			context.SetStatus(InstanceStatus.Running);
 			context.Logger.Information("Session started.");
 		}
 	}
 
-	private void SessionOutput(object? sender, string e) {
-		context.Logger.Verbose("[Server] {Line}", e);
-		logSenderThread.Enqueue(e);
-	}
+	private void ProcessEnded(object? sender, EventArgs e) {
+		if (!runningSessionDisposer.Dispose()) {
+			return;
+		}
 
-	private void SessionEnded(object? sender, EventArgs e) {
-		if (sessionObjects.Dispose()) {
+		if (isStopping) {
 			context.Logger.Information("Session ended.");
-			context.ReportStatus(InstanceStatus.IsNotRunning);
-			context.TransitionState(new InstanceNotRunningState());
+			context.ReportEvent(InstanceEvent.Stopped);
+			context.TransitionState(new InstanceNotRunningState(), InstanceStatus.NotRunning);
+		}
+		else {
+			context.Logger.Information("Session ended unexpectedly, restarting...");
+			context.ReportEvent(InstanceEvent.Crashed);
+			context.TransitionState(new InstanceLaunchingState(context), InstanceStatus.Restarting);
 		}
 	}
 
-	public IInstanceState Launch(InstanceContext context) {
-		return this;
+	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
+		return (this, LaunchInstanceResult.InstanceAlreadyRunning);
 	}
 
-	public IInstanceState Stop() {
-		session.SessionEnded -= SessionEnded;
-		return new InstanceStoppingState(context, session, sessionObjects);
+	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
+		if (stopStrategy == MinecraftStopStrategy.Instant) {
+			CancelDelayedStop();
+			return (PrepareStoppedState(), StopInstanceResult.StopInitiated);
+		}
+
+		if (isStopping) {
+			// TODO change delay or something
+			return (this, StopInstanceResult.InstanceAlreadyStopping);
+		}
+		
+		isStopping = true;
+		context.Services.TaskManager.Run("Delayed stop timer for instance " + context.ShortName, () => StopLater(stopStrategy.Seconds));
+		return (this, StopInstanceResult.StopInitiated);
+	}
+
+	private IInstanceState PrepareStoppedState() {
+		process.Ended -= ProcessEnded;
+		backupScheduler.Stop();
+		return new InstanceStoppingState(context, process, runningSessionDisposer);
+	}
+
+	private void CancelDelayedStop() {
+		try {
+			delayedStopCancellationTokenSource.Cancel();
+		} catch (ObjectDisposedException) {
+			// ignore
+		}
+	}
+
+	private async Task StopLater(int seconds) {
+		var cancellationToken = delayedStopCancellationTokenSource.Token;
+
+		try {
+			stateOwnsDelayedStopCancellationTokenSource = false;
+
+			int[] stops = { 60, 30, 10, 5, 4, 3, 2, 1, 0 };
+			
+			foreach (var stop in stops) {
+				if (seconds > stop) {
+					await SendCommand(MinecraftCommand.Say("Server shutting down in " + seconds + (seconds == 1 ? " second." : " seconds.")), cancellationToken);
+					await Task.Delay(TimeSpan.FromSeconds(seconds - stop), cancellationToken);
+					seconds = stop;
+				}
+			}
+		} catch (OperationCanceledException) {
+			context.Logger.Debug("Cancelled delayed stop.");
+			return;
+		} catch (ObjectDisposedException) {
+			return;
+		} catch (Exception e) {
+			context.Logger.Warning(e, "Caught exception during delayed stop.");
+			return;
+		} finally {
+			delayedStopCancellationTokenSource.Dispose();
+		}
+
+		context.TransitionState(PrepareStoppedState());
 	}
 
 	public async Task<bool> SendCommand(string command, CancellationToken cancellationToken) {
 		try {
 			context.Logger.Information("Sending command: {Command}", command);
-			await session.SendCommand(command, cancellationToken);
+			await process.SendCommand(command, cancellationToken);
 			return true;
 		} catch (OperationCanceledException) {
 			return false;
@@ -66,16 +137,18 @@ sealed class InstanceRunningState : IInstanceState {
 		}
 	}
 
-	public sealed class SessionObjects {
-		private readonly InstanceContext context;
+	private void OnScheduledBackupCompleted(object? sender, BackupCreationResult e) {
+		context.ReportEvent(new InstanceBackupCompletedEvent(e.Kind, e.Warnings));
+	}
+
+	private sealed class RunningSessionDisposer : IDisposable {
+		private readonly InstanceRunningState state;
 		private readonly InstanceSession session;
-		private readonly InstanceLogSenderThread logSenderThread;
 		private bool isDisposed;
 
-		public SessionObjects(InstanceContext context, InstanceSession session, InstanceLogSenderThread logSenderThread) {
-			this.context = context;
+		public RunningSessionDisposer(InstanceRunningState state, InstanceSession session) {
+			this.state = state;
 			this.session = session;
-			this.logSenderThread = logSenderThread;
 		}
 
 		public bool Dispose() {
@@ -87,10 +160,19 @@ sealed class InstanceRunningState : IInstanceState {
 				isDisposed = true;
 			}
 
-			logSenderThread.Cancel();
+			if (state.stateOwnsDelayedStopCancellationTokenSource) {
+				state.delayedStopCancellationTokenSource.Dispose();
+			}
+			else {
+				state.CancelDelayedStop();
+			}
+			
 			session.Dispose();
-			context.PortManager.Release(context.Configuration);
 			return true;
 		}
+
+		void IDisposable.Dispose() {
+			Dispose();
+		}
 	}
 }

Agent/Phantom.Agent.Services/Instances/States/InstanceStoppingState.cs

@@ -1,25 +1,37 @@
-using Phantom.Agent.Minecraft.Instance;
+using System.Diagnostics;
+using Phantom.Agent.Minecraft.Command;
+using Phantom.Agent.Minecraft.Instance;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Agent.Services.Instances.States; 
 
 sealed class InstanceStoppingState : IInstanceState, IDisposable {
 	private readonly InstanceContext context;
-	private readonly InstanceSession session;
-	private readonly InstanceRunningState.SessionObjects sessionObjects;
+	private readonly InstanceProcess process;
+	private readonly IDisposable sessionDisposer;
 
-	public InstanceStoppingState(InstanceContext context, InstanceSession session, InstanceRunningState.SessionObjects sessionObjects) {
-		this.sessionObjects = sessionObjects;
-		this.session = session;
+	public InstanceStoppingState(InstanceContext context, InstanceProcess process, IDisposable sessionDisposer) {
 		this.context = context;
-		this.context.Logger.Information("Session stopping.");
-		this.context.ReportStatus(InstanceStatus.IsStopping);
+		this.process = process;
+		this.sessionDisposer = sessionDisposer;
+	}
 
-		Task.Run(DoStop);
+	public void Initialize() {
+		context.Logger.Information("Session stopping.");
+		context.SetStatus(InstanceStatus.Stopping);
+		context.Services.TaskManager.Run("Stop procedure for instance " + context.ShortName, DoStop);
 	}
 
 	private async Task DoStop() {
 		try {
+			// Do not release the semaphore after this point.
+			if (!await process.BackupSemaphore.CancelAndWait(TimeSpan.FromSeconds(1))) {
+				context.Logger.Information("Waiting for backup to finish...");
+				await process.BackupSemaphore.CancelAndWait(Timeout.InfiniteTimeSpan);
+			}
+			
 			context.Logger.Information("Sending stop command...");
 			await DoSendStopCommand();
 
@@ -27,42 +39,44 @@ sealed class InstanceStoppingState : IInstanceState, IDisposable {
 			await DoWaitForSessionToEnd();
 		} finally {
 			context.Logger.Information("Session stopped.");
-			context.ReportStatus(InstanceStatus.IsNotRunning);
-			context.TransitionState(new InstanceNotRunningState());
+			context.ReportEvent(InstanceEvent.Stopped);
+			context.TransitionState(new InstanceNotRunningState(), InstanceStatus.NotRunning);
 		}
 	}
 
 	private async Task DoSendStopCommand() {
-		using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(5));
+		using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
 		try {
-			await session.SendCommand("stop", cts.Token);
+			await process.SendCommand(MinecraftCommand.Stop, timeout.Token);
 		} catch (OperationCanceledException) {
 			// ignore
+		} catch (ObjectDisposedException e) when (e.ObjectName == typeof(Process).FullName && process.HasEnded) {
+			// ignore
 		} catch (Exception e) {
 			context.Logger.Warning(e, "Caught exception while sending stop command.");
 		}
 	}
 
 	private async Task DoWaitForSessionToEnd() {
-		using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(55));
+		using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(55));
 		try {
-			await session.WaitForExit(cts.Token);
+			await process.WaitForExit(timeout.Token);
 		} catch (OperationCanceledException) {
 			try {
 				context.Logger.Warning("Waiting timed out, killing session...");
-				session.Kill();
+				process.Kill();
 			} catch (Exception e) {
 				context.Logger.Error(e, "Caught exception while killing session.");
 			}
 		}
 	}
 
-	public IInstanceState Launch(InstanceContext context) {
-		return this;
+	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
+		return (this, LaunchInstanceResult.InstanceIsStopping);
 	}
 
-	public IInstanceState Stop() {
-		return this; // TODO maybe provide a way to kill?
+	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
+		return (this, StopInstanceResult.InstanceAlreadyStopping); // TODO maybe provide a way to kill?
 	}
 
 	public Task<bool> SendCommand(string command, CancellationToken cancellationToken) {
@@ -70,6 +84,6 @@ sealed class InstanceStoppingState : IInstanceState, IDisposable {
 	}
 
 	public void Dispose() {
-		sessionObjects.Dispose();
+		sessionDisposer.Dispose();
 	}
 }

Agent/Phantom.Agent.Services/Rpc/MessageListener.cs

@@ -1,10 +1,12 @@
-using NetMQ.Sockets;
-using Phantom.Agent.Rpc;
+using Phantom.Agent.Rpc;
+using Phantom.Common.Data.Instance;
 using Phantom.Common.Data.Replies;
 using Phantom.Common.Logging;
 using Phantom.Common.Messages;
+using Phantom.Common.Messages.BiDirectional;
 using Phantom.Common.Messages.ToAgent;
 using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.Rpc.Message;
 using Serilog;
 
 namespace Phantom.Agent.Services.Rpc;
@@ -12,32 +14,39 @@ namespace Phantom.Agent.Services.Rpc;
 public sealed class MessageListener : IMessageToAgentListener {
 	private static ILogger Logger { get; } = PhantomLogger.Create<MessageListener>();
 
-	private readonly ClientSocket socket;
+	private readonly RpcServerConnection connection;
 	private readonly AgentServices agent;
 	private readonly CancellationTokenSource shutdownTokenSource;
 
-	public MessageListener(ClientSocket socket, AgentServices agent, CancellationTokenSource shutdownTokenSource) {
-		this.socket = socket;
+	public MessageListener(RpcServerConnection connection, AgentServices agent, CancellationTokenSource shutdownTokenSource) {
+		this.connection = connection;
 		this.agent = agent;
 		this.shutdownTokenSource = shutdownTokenSource;
 	}
 
-	public async Task HandleRegisterAgentSuccessResult(RegisterAgentSuccessMessage message) {
+	public async Task<NoReply> HandleRegisterAgentSuccess(RegisterAgentSuccessMessage message) {
 		Logger.Information("Agent authentication successful.");
 
-		foreach (var instanceInfo in message.InitialInstances) {
-			if (await agent.InstanceSessionManager.Configure(instanceInfo) != ConfigureInstanceResult.Success) {
-				Logger.Fatal("Unable to configure instance \"{Name}\" (GUID {Guid}), shutting down.", instanceInfo.InstanceName, instanceInfo.InstanceGuid);
+		void ShutdownAfterConfigurationFailed(InstanceConfiguration configuration) {
+			Logger.Fatal("Unable to configure instance \"{Name}\" (GUID {Guid}), shutting down.", configuration.InstanceName, configuration.InstanceGuid);
+			shutdownTokenSource.Cancel();
+		}
 		
-				shutdownTokenSource.Cancel();
-				return;
+		foreach (var configureInstanceMessage in message.InitialInstanceConfigurations) {
+			var result = await HandleConfigureInstance(configureInstanceMessage, alwaysReportStatus: true);
+			if (!result.Is(ConfigureInstanceResult.Success)) {
+				ShutdownAfterConfigurationFailed(configureInstanceMessage.Configuration);
+				return NoReply.Instance;
 			}
 		}
 
-		await ServerMessaging.SendMessage(new AdvertiseJavaRuntimesMessage(agent.JavaRuntimeRepository.All));
+		await ServerMessaging.Send(new AdvertiseJavaRuntimesMessage(agent.JavaRuntimeRepository.All));
+		await agent.InstanceSessionManager.RefreshAgentStatus();
+		
+		return NoReply.Instance;
 	}
 
-	public Task HandleRegisterAgentFailureResult(RegisterAgentFailureMessage message) {
+	public Task<NoReply> HandleRegisterAgentFailure(RegisterAgentFailureMessage message) {
 		string errorMessage = message.FailureKind switch {
 			RegisterAgentFailure.ConnectionAlreadyHasAnAgent => "This connection already has an associated agent.",
 			RegisterAgentFailure.InvalidToken                => "Invalid token.",
@@ -47,22 +56,31 @@ public sealed class MessageListener : IMessageToAgentListener {
 		Logger.Fatal("Agent authentication failed: {Error}", errorMessage);
 		Environment.Exit(1);
 
-		return Task.CompletedTask;
+		return Task.FromResult(NoReply.Instance);
 	}
 	
-	public async Task HandleConfigureInstance(ConfigureInstanceMessage message) {
-		await socket.SendSimpleReply(message, await agent.InstanceSessionManager.Configure(message.Configuration));
+	private Task<InstanceActionResult<ConfigureInstanceResult>> HandleConfigureInstance(ConfigureInstanceMessage message, bool alwaysReportStatus) {
+		return agent.InstanceSessionManager.Configure(message.Configuration, message.LaunchProperties, message.LaunchNow, alwaysReportStatus);
 	}
 	
-	public async Task HandleLaunchInstance(LaunchInstanceMessage message) {
-		await socket.SendSimpleReply(message, await agent.InstanceSessionManager.Launch(message.InstanceGuid));
+	public async Task<InstanceActionResult<ConfigureInstanceResult>> HandleConfigureInstance(ConfigureInstanceMessage message) {
+		return await HandleConfigureInstance(message, alwaysReportStatus: false);
 	}
 
-	public async Task HandleStopInstance(StopInstanceMessage message) {
-		await socket.SendSimpleReply(message, await agent.InstanceSessionManager.Stop(message.InstanceGuid));
+	public async Task<InstanceActionResult<LaunchInstanceResult>> HandleLaunchInstance(LaunchInstanceMessage message) {
+		return await agent.InstanceSessionManager.Launch(message.InstanceGuid);
 	}
 
-	public async Task HandleSendCommandToInstance(SendCommandToInstanceMessage message) {
-		await socket.SendSimpleReply(message, await agent.InstanceSessionManager.SendCommand(message.InstanceGuid, message.Command));
+	public async Task<InstanceActionResult<StopInstanceResult>> HandleStopInstance(StopInstanceMessage message) {
+		return await agent.InstanceSessionManager.Stop(message.InstanceGuid, message.StopStrategy);
+	}
+
+	public async Task<InstanceActionResult<SendCommandToInstanceResult>> HandleSendCommandToInstance(SendCommandToInstanceMessage message) {
+		return await agent.InstanceSessionManager.SendCommand(message.InstanceGuid, message.Command);
+	}
+
+	public Task<NoReply> HandleReply(ReplyMessage message) {
+		connection.Receive(message);
+		return Task.FromResult(NoReply.Instance);
 	}
 }

Agent/Phantom.Agent/AgentKey.cs

@@ -0,0 +1,60 @@
+using NetMQ;
+using Phantom.Common.Data.Agent;
+using Phantom.Common.Logging;
+using Phantom.Utils.Cryptography;
+using Phantom.Utils.IO;
+using Serilog;
+
+namespace Phantom.Agent;
+
+static class AgentKey {
+	private static ILogger Logger { get; } = PhantomLogger.Create(nameof(AgentKey));
+
+	public static Task<(NetMQCertificate, AgentAuthToken)?> Load(string? agentKeyToken, string? agentKeyFilePath) {
+		if (agentKeyFilePath != null) {
+			return LoadFromFile(agentKeyFilePath);
+		}
+		else if (agentKeyToken != null) {
+			return Task.FromResult(LoadFromToken(agentKeyToken));
+		}
+		else {
+			throw new InvalidOperationException();
+		}
+	}
+
+	private static async Task<(NetMQCertificate, AgentAuthToken)?> LoadFromFile(string agentKeyFilePath) {
+		if (!File.Exists(agentKeyFilePath)) {
+			Logger.Fatal("Missing agent key file: {AgentKeyFilePath}", agentKeyFilePath);
+			return null;
+		}
+
+		try {
+			Files.RequireMaximumFileSize(agentKeyFilePath, 64);
+			return LoadFromBytes(await File.ReadAllBytesAsync(agentKeyFilePath));
+		} catch (IOException e) {
+			Logger.Fatal("Error loading agent key from file: {AgentKeyFilePath}", agentKeyFilePath);
+			Logger.Fatal(e.Message);
+			return null;
+		} catch (Exception) {
+			Logger.Fatal("File does not contain a valid agent key: {AgentKeyFilePath}", agentKeyFilePath);
+			return null;
+		}
+	}
+
+	private static (NetMQCertificate, AgentAuthToken)? LoadFromToken(string agentKey) {
+		try {
+			return LoadFromBytes(TokenGenerator.DecodeBytes(agentKey));
+		} catch (Exception) {
+			Logger.Fatal("Invalid agent key: {AgentKey}", agentKey);
+			return null;
+		}
+	}
+
+	private static (NetMQCertificate, AgentAuthToken)? LoadFromBytes(byte[] agentKey) {
+		var (publicKey, agentToken) = AgentKeyData.FromBytes(agentKey);
+		var serverCertificate = NetMQCertificate.FromPublicKey(publicKey);
+		
+		Logger.Information("Loaded agent key.");
+		return (serverCertificate, agentToken);
+	}
+}

Agent/Phantom.Agent/AgentNameGenerator.cs

@@ -1,476 +0,0 @@
-using Phantom.Utils.Cryptography;
-
-namespace Phantom.Agent;
-
-static class AgentNameGenerator {
-	private static readonly string[] Prefixes = {
-		"Abundant",
-		"Ancient",
-		"Broken",
-		"Crushed",
-		"Damaged",
-		"Dark",
-		"Divine",
-		"Enchanted",
-		"Flaming",
-		"Frozen",
-		"Gilded",
-		"Glowing",
-		"Immaculate",
-		"Infested",
-		"Invisible",
-		"Luxurious",
-		"Mossy",
-		"Mysterious",
-		"Opulent",
-		"Perplexing",
-		"Possessed",
-		"Pristine",
-		"Rotting",
-		"Sophisticated",
-		"Spectacular",
-		"Stunning",
-		"Tenacious",
-		"Twisted",
-		"Unique",
-		"Venerable",
-		"Withering"
-	};
-
-	private static readonly string[] Suffixes = {
-		"Acacia Button",
-		"Acacia Door",
-		"Acacia Fence",
-		"Acacia Leaves",
-		"Acacia Log",
-		"Acacia Planks",
-		"Acacia Sapling",
-		"Acacia Sign",
-		"Acacia Slab",
-		"Acacia Stairs",
-		"Acacia Trapdoor",
-		"Acacia Wood",
-		"Activator Rail",
-		"Allium",
-		"Ancient Debris",
-		"Andesite Slab",
-		"Andesite Stairs",
-		"Andesite Wall",
-		"Andesite",
-		"Anvil",
-		"Azalea Leaves",
-		"Azalea",
-		"Azure Bluet",
-		"Bamboo",
-		"Barrel",
-		"Basalt",
-		"Beacon",
-		"Bedrock",
-		"Bee Nest",
-		"Beehive",
-		"Beetroots",
-		"Bell",
-		"Birch Button",
-		"Birch Door",
-		"Birch Fence",
-		"Birch Leaves",
-		"Birch Log",
-		"Birch Planks",
-		"Birch Sapling",
-		"Birch Sign",
-		"Birch Slab",
-		"Birch Stairs",
-		"Birch Trapdoor",
-		"Birch Wood",
-		"Black Candle",
-		"Black Carpet",
-		"Black Concrete",
-		"Black Terracotta",
-		"Black Wool",
-		"Blackstone Slab",
-		"Blackstone Stairs",
-		"Blackstone Wall",
-		"Blackstone",
-		"Blast Furnace",
-		"Blue Candle",
-		"Blue Carpet",
-		"Blue Concrete",
-		"Blue Ice",
-		"Blue Orchid",
-		"Blue Terracotta",
-		"Blue Wool",
-		"Bone Block",
-		"Bookshelf",
-		"Brain Coral",
-		"Brewing Stand",
-		"Brick Slab",
-		"Brick Stairs",
-		"Brick Wall",
-		"Bricks",
-		"Brown Candle",
-		"Brown Carpet",
-		"Brown Concrete",
-		"Brown Mushroom",
-		"Brown Terracotta",
-		"Brown Wool",
-		"Bubble Column",
-		"Bubble Coral",
-		"Cactus",
-		"Cake",
-		"Calcite",
-		"Campfire",
-		"Candle",
-		"Carrots",
-		"Cartography Table",
-		"Carved Pumpkin",
-		"Cauldron",
-		"Cave Vines",
-		"Chain",
-		"Chest",
-		"Chorus Flower",
-		"Chorus Plant",
-		"Clay",
-		"Coal Ore",
-		"Coarse Dirt",
-		"Cobbled Deepslate",
-		"Cobblestone Slab",
-		"Cobblestone Stairs",
-		"Cobblestone Wall",
-		"Cobblestone",
-		"Cobweb",
-		"Cocoa",
-		"Composter",
-		"Conduit",
-		"Copper Ore",
-		"Cornflower",
-		"Crafting Table",
-		"Creeper Head",
-		"Crimson Button",
-		"Crimson Door",
-		"Crimson Fence",
-		"Crimson Fungus",
-		"Crimson Hyphae",
-		"Crimson Nylium",
-		"Crimson Planks",
-		"Crimson Roots",
-		"Crimson Sign",
-		"Crimson Slab",
-		"Crimson Stairs",
-		"Crimson Stem",
-		"Crimson Trapdoor",
-		"Crying Obsidian",
-		"Cyan Candle",
-		"Cyan Carpet",
-		"Cyan Concrete",
-		"Cyan Terracotta",
-		"Cyan Wool",
-		"Dandelion",
-		"Dead Bush",
-		"Deepslate Bricks",
-		"Deepslate Tiles",
-		"Deepslate",
-		"Detector Rail",
-		"Diamond Ore",
-		"Diorite Slab",
-		"Diorite Stairs",
-		"Diorite Wall",
-		"Diorite",
-		"Dirt",
-		"Dispenser",
-		"Dragon Egg",
-		"Dragon Head",
-		"Dripstone Block",
-		"Dropper",
-		"Emerald Ore",
-		"Enchanting Table",
-		"End Gateway",
-		"End Portal",
-		"End Rod",
-		"End Stone",
-		"Ender Chest",
-		"Farmland",
-		"Fern",
-		"Fire Coral",
-		"Fletching Table",
-		"Flower Pot",
-		"Flowering Azalea",
-		"Frosted Ice",
-		"Furnace",
-		"Glass Pane",
-		"Glass",
-		"Glowstone",
-		"Gold Ore",
-		"Granite Slab",
-		"Granite Stairs",
-		"Granite Wall",
-		"Granite",
-		"Grass Block",
-		"Grass",
-		"Gravel",
-		"Gray Candle",
-		"Gray Carpet",
-		"Gray Concrete",
-		"Gray Terracotta",
-		"Gray Wool",
-		"Green Candle",
-		"Green Carpet",
-		"Green Concrete",
-		"Green Terracotta",
-		"Green Wool",
-		"Grindstone",
-		"Hay Bale",
-		"Honey Block",
-		"Hopper",
-		"Horn Coral",
-		"Ice",
-		"Iron Bars",
-		"Iron Door",
-		"Iron Ore",
-		"Iron Trapdoor",
-		"Jack o'Lantern",
-		"Jigsaw Block",
-		"Jukebox",
-		"Jungle Button",
-		"Jungle Door",
-		"Jungle Fence",
-		"Jungle Leaves",
-		"Jungle Log",
-		"Jungle Planks",
-		"Jungle Sapling",
-		"Jungle Sign",
-		"Jungle Slab",
-		"Jungle Stairs",
-		"Jungle Trapdoor",
-		"Jungle Wood",
-		"Kelp Plant",
-		"Kelp",
-		"Ladder",
-		"Lantern",
-		"Large Fern",
-		"Lava",
-		"Lectern",
-		"Lever",
-		"Lightning Rod",
-		"Lilac",
-		"Lily Pad",
-		"Lime Candle",
-		"Lime Carpet",
-		"Lime Concrete",
-		"Lime Terracotta",
-		"Lime Wool",
-		"Lodestone",
-		"Loom",
-		"Magenta Candle",
-		"Magenta Carpet",
-		"Magenta Concrete",
-		"Magenta Terracotta",
-		"Magenta Wool",
-		"Magma Block",
-		"Mangrove Button",
-		"Mangrove Door",
-		"Mangrove Fence",
-		"Mangrove Leaves",
-		"Mangrove Log",
-		"Mangrove Planks",
-		"Mangrove Propagule",
-		"Mangrove Roots",
-		"Mangrove Sign",
-		"Mangrove Slab",
-		"Mangrove Stairs",
-		"Mangrove Trapdoor",
-		"Mangrove Wood",
-		"Melon Stem",
-		"Melon",
-		"Moss Block",
-		"Moss Carpet",
-		"Mossy Cobblestone",
-		"Mud Bricks",
-		"Mud",
-		"Mushroom Stem",
-		"Mycelium",
-		"Nether Bricks",
-		"Nether Portal",
-		"Nether Sprouts",
-		"Nether Wart",
-		"Netherrack",
-		"Note Block",
-		"Oak Button",
-		"Oak Door",
-		"Oak Fence",
-		"Oak Leaves",
-		"Oak Log",
-		"Oak Planks",
-		"Oak Sapling",
-		"Oak Sign",
-		"Oak Slab",
-		"Oak Stairs",
-		"Oak Trapdoor",
-		"Oak Wood",
-		"Observer",
-		"Obsidian",
-		"Ominous Banner",
-		"Orange Candle",
-		"Orange Carpet",
-		"Orange Concrete",
-		"Orange Terracotta",
-		"Orange Tulip",
-		"Orange Wool",
-		"Oxeye Daisy",
-		"Oxidized Copper",
-		"Packed Ice",
-		"Packed Mud",
-		"Peony",
-		"Pink Candle",
-		"Pink Carpet",
-		"Pink Concrete",
-		"Pink Terracotta",
-		"Pink Tulip",
-		"Pink Wool",
-		"Piston",
-		"Podzol",
-		"Pointed Dripstone",
-		"Polished Andesite",
-		"Polished Basalt",
-		"Polished Blackstone",
-		"Polished Deepslate",
-		"Polished Diorite",
-		"Polished Granite",
-		"Poppy",
-		"Potatoes",
-		"Powder Snow",
-		"Powered Rail",
-		"Prismarine Bricks",
-		"Prismarine Slab",
-		"Prismarine Stairs",
-		"Prismarine Wall",
-		"Prismarine",
-		"Pumpkin Stem",
-		"Pumpkin",
-		"Purple Candle",
-		"Purple Carpet",
-		"Purple Concrete",
-		"Purple Terracotta",
-		"Purple Wool",
-		"Purpur Block",
-		"Purpur Pillar",
-		"Purpur Slab",
-		"Purpur Stairs",
-		"Quartz Bricks",
-		"Quartz Pillar",
-		"Quartz Slab",
-		"Quartz Stairs",
-		"Rail",
-		"Red Candle",
-		"Red Carpet",
-		"Red Concrete",
-		"Red Mushroom",
-		"Red Sand",
-		"Red Sandstone",
-		"Red Terracotta",
-		"Red Tulip",
-		"Red Wool",
-		"Redstone Lamp",
-		"Redstone Ore",
-		"Redstone Torch",
-		"Redstone Wire",
-		"Reinforced Deepslate",
-		"Rooted Dirt",
-		"Rose Bush",
-		"Sand",
-		"Sandstone Slab",
-		"Sandstone Stairs",
-		"Sandstone Wall",
-		"Sandstone",
-		"Scaffolding",
-		"Sea Lantern",
-		"Sea Pickle",
-		"Seagrass",
-		"Shroomlight",
-		"Shulker Box",
-		"Skeleton Skull",
-		"Slime Block",
-		"Smithing Table",
-		"Smoker",
-		"Smooth Basalt",
-		"Smooth Sandstone",
-		"Smooth Stone",
-		"Snow Block",
-		"Snow",
-		"Soul Lantern",
-		"Soul Sand",
-		"Soul Torch",
-		"Sponge",
-		"Spore Blossom",
-		"Spruce Button",
-		"Spruce Door",
-		"Spruce Fence",
-		"Spruce Leaves",
-		"Spruce Log",
-		"Spruce Planks",
-		"Spruce Sapling",
-		"Spruce Sign",
-		"Spruce Slab",
-		"Spruce Stairs",
-		"Spruce Trapdoor",
-		"Spruce Wood",
-		"Sticky Piston",
-		"Stone Bricks",
-		"Stone Button",
-		"Stone Slab",
-		"Stone Stairs",
-		"Stone",
-		"Stonecutter",
-		"Sugar Cane",
-		"Sunflower",
-		"TNT",
-		"Target",
-		"Terracotta",
-		"Tinted Glass",
-		"Torch",
-		"Trapped Chest",
-		"Tripwire Hook",
-		"Tripwire",
-		"Tube Coral",
-		"Tuff",
-		"Turtle Egg",
-		"Twisting Vines",
-		"Verdant Froglight",
-		"Vines",
-		"Warped Button",
-		"Warped Door",
-		"Warped Fence",
-		"Warped Fungus",
-		"Warped Hyphae",
-		"Warped Nylium",
-		"Warped Planks",
-		"Warped Roots",
-		"Warped Sign",
-		"Warped Slab",
-		"Warped Stairs",
-		"Warped Stem",
-		"Warped Trapdoor",
-		"Water",
-		"Weeping Vines",
-		"Wheat Crops",
-		"White Candle",
-		"White Carpet",
-		"White Concrete",
-		"White Terracotta",
-		"White Tulip",
-		"White Wool",
-		"Wither Rose",
-		"Yellow Candle",
-		"Yellow Carpet",
-		"Yellow Concrete",
-		"Yellow Terracotta",
-		"Yellow Wool",
-		"Zombie Head"
-	};
-
-	public static string GenerateFrom(Guid guid) {
-		var rand = new Random(StableHashCode.ForString(guid.ToString()));
-		string prefix = Prefixes[rand.Next(Prefixes.Length)];
-		string suffix = Suffixes[rand.Next(Suffixes.Length)];
-		return string.Concat(prefix, " ", suffix);
-	}
-}

Agent/Phantom.Agent/CertificateFile.cs

@@ -1,32 +0,0 @@
-using NetMQ;
-using Phantom.Common.Logging;
-using Phantom.Utils.IO;
-using Serilog;
-
-namespace Phantom.Agent;
-
-static class CertificateFile {
-	private static ILogger Logger { get; } = PhantomLogger.Create(typeof(CertificateFile));
-
-	public static async Task<NetMQCertificate?> LoadPublicKey(string publicKeyFilePath) {
-		if (!File.Exists(publicKeyFilePath)) {
-			Logger.Fatal("Cannot load server certificate, missing key file: {PublicKeyFilePath}", publicKeyFilePath);
-			return null;
-		}
-
-		try {
-			var publicKey = await LoadPublicKeyFromFile(publicKeyFilePath);
-			Logger.Information("Loaded server certificate.");
-			return publicKey;
-		} catch (Exception e) {
-			Logger.Fatal(e, "Error loading server certificate from key file: {PublicKeyFilePath}", publicKeyFilePath);
-			return null;
-		}
-	}
-
-	private static async Task<NetMQCertificate> LoadPublicKeyFromFile(string filePath) {
-		Files.RequireMaximumFileSize(filePath, 1024);
-		byte[] publicKey = await File.ReadAllBytesAsync(filePath);
-		return NetMQCertificate.FromPublicKey(publicKey);
-	}
-}

Agent/Phantom.Agent/GuidFile.cs

@@ -6,7 +6,7 @@ using Serilog;
 namespace Phantom.Agent; 
 
 static class GuidFile {
-	private static ILogger Logger { get; } = PhantomLogger.Create(typeof(GuidFile));
+	private static ILogger Logger { get; } = PhantomLogger.Create(nameof(GuidFile));
 
 	private const string GuidFileName = "agent.guid";
 	

Agent/Phantom.Agent/Phantom.Agent.csproj

@@ -8,6 +8,7 @@
   
   <PropertyGroup>
     <OutputType>Exe</OutputType>
+    <SatelliteResourceLanguages>en</SatelliteResourceLanguages>
   </PropertyGroup>
   
   <ItemGroup>

Agent/Phantom.Agent/Program.cs

@@ -1,4 +1,5 @@
-using Phantom.Agent;
+using System.Reflection;
+using Phantom.Agent;
 using Phantom.Agent.Rpc;
 using Phantom.Agent.Services;
 using Phantom.Agent.Services.Rpc;
@@ -7,31 +8,25 @@ using Phantom.Common.Logging;
 using Phantom.Utils.Rpc;
 using Phantom.Utils.Runtime;
 
-const int AgentVersion = 1;
+const int ProtocolVersion = 1;
 
-var cancellationTokenSource = new CancellationTokenSource();
+var shutdownCancellationTokenSource = new CancellationTokenSource();
+var shutdownCancellationToken = shutdownCancellationTokenSource.Token;
 
-PosixSignals.RegisterCancellation(cancellationTokenSource, static () => {
+PosixSignals.RegisterCancellation(shutdownCancellationTokenSource, static () => {
 	PhantomLogger.Root.InformationHeading("Stopping Phantom Panel agent...");
 });
 
 try {
+	var fullVersion = AssemblyAttributes.GetFullVersion(Assembly.GetExecutingAssembly());
+
 	PhantomLogger.Root.InformationHeading("Initializing Phantom Panel agent...");
+	PhantomLogger.Root.Information("Agent version: {Version}", fullVersion);
 
-	var (serverHost, serverPort, javaSearchPath, authToken, authTokenFilePath, agentNameOrEmpty, maxInstances, maxMemory, allowedServerPorts, allowedRconPorts) = Variables.LoadOrExit();
+	var (serverHost, serverPort, javaSearchPath, agentKeyToken, agentKeyFilePath, agentName, maxInstances, maxMemory, allowedServerPorts, allowedRconPorts) = Variables.LoadOrExit();
 
-	AgentAuthToken agentAuthToken;
-	try {
-		agentAuthToken = authTokenFilePath == null ? new AgentAuthToken(authToken) : await AgentAuthToken.ReadFromFile(authTokenFilePath);
-	} catch (Exception e) {
-		PhantomLogger.Root.Fatal(e, "Error reading auth token.");
-		Environment.Exit(1);
-		return;
-	}
-
-	string serverPublicKeyPath = Path.GetFullPath("./secrets/agent.key");
-	var serverCertificate = await CertificateFile.LoadPublicKey(serverPublicKeyPath);
-	if (serverCertificate == null) {
+	var agentKey = await AgentKey.Load(agentKeyToken, agentKeyFilePath);
+	if (agentKey == null) {
 		Environment.Exit(1);
 	}
 
@@ -43,22 +38,40 @@ try {
 	var agentGuid = await GuidFile.CreateOrLoad(folders.DataFolderPath);
 	if (agentGuid == null) {
 		Environment.Exit(1);
-		return;
 	}
 
-	var agentName = string.IsNullOrEmpty(agentNameOrEmpty) ? AgentNameGenerator.GenerateFrom(agentGuid.Value) : agentNameOrEmpty;
-	var agentInfo = new AgentInfo(agentGuid.Value, agentName, AgentVersion, maxInstances, maxMemory, allowedServerPorts, allowedRconPorts);
+	var (serverCertificate, agentToken) = agentKey.Value;
+	var agentInfo = new AgentInfo(agentGuid.Value, agentName, ProtocolVersion, fullVersion, maxInstances, maxMemory, allowedServerPorts, allowedRconPorts);
 	var agentServices = new AgentServices(agentInfo, folders);
 
+	MessageListener MessageListenerFactory(RpcServerConnection connection) {
+		return new MessageListener(connection, agentServices, shutdownCancellationTokenSource);
+	}
+
 	PhantomLogger.Root.InformationHeading("Launching Phantom Panel agent...");
 
 	await agentServices.Initialize();
-	await RpcLauncher.Launch(new RpcConfiguration(PhantomLogger.Create("Rpc"), serverHost, serverPort, serverCertificate, cancellationTokenSource.Token), agentAuthToken, agentInfo, socket => new MessageListener(socket, agentServices, cancellationTokenSource));
-	await agentServices.Shutdown();
+
+	var rpcDisconnectSemaphore = new SemaphoreSlim(0, 1);
+	var rpcConfiguration = new RpcConfiguration(PhantomLogger.Create("Rpc"), PhantomLogger.Create<TaskManager>("Rpc"), serverHost, serverPort, serverCertificate);
+	var rpcTask = RpcLauncher.Launch(rpcConfiguration, agentToken, agentInfo, MessageListenerFactory, rpcDisconnectSemaphore, shutdownCancellationToken);
+	try {
+		await rpcTask.WaitAsync(shutdownCancellationToken);
+	} finally {
+		shutdownCancellationTokenSource.Cancel();
+		await agentServices.Shutdown();
+
+		rpcDisconnectSemaphore.Release();
+		await rpcTask;
+		rpcDisconnectSemaphore.Dispose();
+	}
 } catch (OperationCanceledException) {
 	// Ignore.
+} catch (Exception e) {
+	PhantomLogger.Root.Fatal(e, "Caught exception in entry point.");
 } finally {
-	cancellationTokenSource.Dispose();
+	shutdownCancellationTokenSource.Dispose();
+
 	PhantomLogger.Root.Information("Bye!");
 	PhantomLogger.Dispose();
 }

Agent/Phantom.Agent/Variables.cs

@@ -9,29 +9,29 @@ sealed record Variables(
 	string ServerHost,
 	ushort ServerPort,
 	string JavaSearchPath,
-	string? AuthToken,
-	string? AuthTokenFilePath,
-	string AgentNameOrEmpty,
+	string? AgentKeyToken,
+	string? AgentKeyFilePath,
+	string AgentName,
 	ushort MaxInstances,
 	RamAllocationUnits MaxMemory,
 	AllowedPorts AllowedServerPorts,
 	AllowedPorts AllowedRconPorts
 ) {
 	private static Variables LoadOrThrow() {
-		var (authToken, authTokenFilePath) = EnvironmentVariables.GetEitherString("SERVER_AUTH_TOKEN", "SERVER_AUTH_TOKEN_FILE").OrThrow;
-		var javaSearchPath = EnvironmentVariables.GetString("JAVA_SEARCH_PATH").OrGetDefault(GetDefaultJavaSearchPath);
+		var (agentKeyToken, agentKeyFilePath) = EnvironmentVariables.GetEitherString("AGENT_KEY", "AGENT_KEY_FILE").Require;
+		var javaSearchPath = EnvironmentVariables.GetString("JAVA_SEARCH_PATH").WithDefaultGetter(GetDefaultJavaSearchPath);
 
 		return new Variables(
-			EnvironmentVariables.GetString("SERVER_HOST").OrThrow,
-			EnvironmentVariables.GetPortNumber("SERVER_PORT").OrDefault(9401),
+			EnvironmentVariables.GetString("SERVER_HOST").Require,
+			EnvironmentVariables.GetPortNumber("SERVER_PORT").WithDefault(9401),
 			javaSearchPath,
-			authToken,
-			authTokenFilePath,
-			EnvironmentVariables.GetString("AGENT_NAME").OrDefault(string.Empty),
-			(ushort) EnvironmentVariables.GetInteger("MAX_INSTANCES", min: 1, max: 10000).OrThrow,
-			EnvironmentVariables.GetString("MAX_MEMORY").MapParse(RamAllocationUnits.FromString).OrThrow,
-			EnvironmentVariables.GetString("ALLOWED_SERVER_PORTS").MapParse(AllowedPorts.FromString).OrThrow,
-			EnvironmentVariables.GetString("ALLOWED_RCON_PORTS").MapParse(AllowedPorts.FromString).OrThrow
+			agentKeyToken,
+			agentKeyFilePath,
+			EnvironmentVariables.GetString("AGENT_NAME").Require,
+			(ushort) EnvironmentVariables.GetInteger("MAX_INSTANCES", min: 1, max: 10000).Require,
+			EnvironmentVariables.GetString("MAX_MEMORY").MapParse(RamAllocationUnits.FromString).Require,
+			EnvironmentVariables.GetString("ALLOWED_SERVER_PORTS").MapParse(AllowedPorts.FromString).Require,
+			EnvironmentVariables.GetString("ALLOWED_RCON_PORTS").MapParse(AllowedPorts.FromString).Require
 		);
 	}
 

Common/Phantom.Common.Data.Tests/Phantom.Common.Data.Tests.csproj

@@ -11,11 +11,11 @@
   </PropertyGroup>
   
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.3.2" />
-    <PackageReference Include="NUnit" Version="3.13.3" />
-    <PackageReference Include="NUnit3TestAdapter" Version="4.2.1" />
-    <PackageReference Include="NUnit.Analyzers" Version="3.3.0" />
-    <PackageReference Include="coverlet.collector" Version="3.1.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="NUnit" />
+    <PackageReference Include="NUnit3TestAdapter" />
+    <PackageReference Include="NUnit.Analyzers" />
+    <PackageReference Include="coverlet.collector" />
   </ItemGroup>
   
   <ItemGroup>

Common/Phantom.Common.Data/Agent/AgentAuthToken.cs

@@ -1,56 +1,39 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Security.Cryptography;
-using System.Text;
-using MessagePack;
-using Phantom.Utils.Cryptography;
-using Phantom.Utils.IO;
+using MemoryPack;
 
 namespace Phantom.Common.Data.Agent;
 
-[MessagePackObject]
+[MemoryPackable]
 [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
-public sealed class AgentAuthToken {
-	private const int MinimumTokenLength = 30;
-	private const int MaximumTokenLength = 100;
+public sealed partial class AgentAuthToken {
+	internal const int Length = 12;
 
-	[Key(0)]
-	public string Value { get; }
-
-	[IgnoreMember]
+	[MemoryPackOrder(0)]
+	[MemoryPackInclude]
 	private readonly byte[] bytes;
 
-	public AgentAuthToken(string? value) {
-		if (value == null) {
-			throw new ArgumentNullException(nameof(value));
+	internal AgentAuthToken(byte[]? bytes) {
+		if (bytes == null) {
+			throw new ArgumentNullException(nameof(bytes));
 		}
 
-		if (value.Length is < MinimumTokenLength or > MaximumTokenLength) {
-			throw new ArgumentOutOfRangeException(nameof(value), "Invalid token length: " + value.Length + ". Token length must be between " + MinimumTokenLength + " and " + MaximumTokenLength + ".");
+		if (bytes.Length != Length) {
+			throw new ArgumentOutOfRangeException(nameof(bytes), "Invalid token length: " + bytes.Length + ". Token length must be exactly " + Length + " bytes.");
 		}
 
-		this.Value = value;
-		this.bytes = TokenGenerator.GetBytesOrThrow(value);
+		this.bytes = bytes;
 	}
 
 	public bool FixedTimeEquals(AgentAuthToken providedAuthToken) {
 		return CryptographicOperations.FixedTimeEquals(bytes, providedAuthToken.bytes);
 	}
 
-	public override string ToString() {
-		return Value;
-	}
-
-	public async Task WriteToFile(string filePath) {
-		await Files.WriteBytesAsync(filePath, bytes, FileMode.Create, Chmod.URW_GR);
-	}
-
-	public static async Task<AgentAuthToken> ReadFromFile(string filePath) {
-		Files.RequireMaximumFileSize(filePath, MaximumTokenLength + 1);
-		string contents = await File.ReadAllTextAsync(filePath, Encoding.ASCII);
-		return new AgentAuthToken(contents.Trim());
+	internal void WriteTo(Span<byte> span) {
+		bytes.CopyTo(span);
 	}
 
 	public static AgentAuthToken Generate() {
-		return new AgentAuthToken(TokenGenerator.Create(MinimumTokenLength));
+		return new AgentAuthToken(RandomNumberGenerator.GetBytes(Length));
 	}
 }

Common/Phantom.Common.Data/Agent/AgentInfo.cs

@@ -1,14 +1,15 @@
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data.Agent;
 
-[MessagePackObject]
-public sealed record AgentInfo(
-	[property: Key(0)] Guid Guid,
-	[property: Key(1)] string Name,
-	[property: Key(2)] ushort Version,
-	[property: Key(3)] ushort MaxInstances,
-	[property: Key(4)] RamAllocationUnits MaxMemory,
-	[property: Key(5)] AllowedPorts AllowedServerPorts,
-	[property: Key(6)] AllowedPorts AllowedRconPorts
+[MemoryPackable]
+public sealed partial record AgentInfo(
+	[property: MemoryPackOrder(0)] Guid Guid,
+	[property: MemoryPackOrder(1)] string Name,
+	[property: MemoryPackOrder(2)] ushort ProtocolVersion,
+	[property: MemoryPackOrder(3)] string BuildVersion,
+	[property: MemoryPackOrder(4)] ushort MaxInstances,
+	[property: MemoryPackOrder(5)] RamAllocationUnits MaxMemory,
+	[property: MemoryPackOrder(6)] AllowedPorts AllowedServerPorts,
+	[property: MemoryPackOrder(7)] AllowedPorts AllowedRconPorts
 );

Common/Phantom.Common.Data/Agent/AgentKeyData.cs

@@ -0,0 +1,18 @@
+namespace Phantom.Common.Data.Agent;
+
+public static class AgentKeyData {
+	private const byte TokenLength = AgentAuthToken.Length;
+
+	public static byte[] ToBytes(byte[] publicKey, AgentAuthToken agentToken) {
+		Span<byte> agentKey = stackalloc byte[TokenLength + publicKey.Length];
+		agentToken.WriteTo(agentKey[..TokenLength]);
+		publicKey.CopyTo(agentKey[TokenLength..]);
+		return agentKey.ToArray();
+	}
+
+	public static (byte[] PublicKey, AgentAuthToken AgentToken) FromBytes(byte[] agentKey) {
+		var token = new AgentAuthToken(agentKey[..TokenLength]);
+		var publicKey = agentKey[TokenLength..];
+		return (publicKey, token);
+	}
+}

Common/Phantom.Common.Data/AllowedPorts.cs

@@ -1,29 +1,28 @@
 using System.Collections.Immutable;
-using System.Diagnostics.CodeAnalysis;
 using System.Text;
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data;
 
-[MessagePackObject]
-[SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
-public sealed class AllowedPorts {
-	[Key(0)]
-	public ImmutableArray<PortRange> AllDefinitions { get; }
+[MemoryPackable]
+public sealed partial class AllowedPorts {
+	[MemoryPackOrder(0)]
+	[MemoryPackInclude]
+	private	readonly ImmutableArray<PortRange> allDefinitions;
 
-	public AllowedPorts(ImmutableArray<PortRange> allDefinitions) {
+	private AllowedPorts(ImmutableArray<PortRange> allDefinitions) {
 		// TODO normalize and deduplicate ranges
-		this.AllDefinitions = allDefinitions.Sort(static (def1, def2) => def1.FirstPort - def2.FirstPort);
+		this.allDefinitions = allDefinitions.Sort(static (def1, def2) => def1.FirstPort - def2.FirstPort);
 	}
 
 	public bool Contains(ushort port) {
-		return AllDefinitions.Any(definition => definition.Contains(port));
+		return allDefinitions.Any(definition => definition.Contains(port));
 	}
 
 	public override string ToString() {
 		var builder = new StringBuilder();
 
-		foreach (var definition in AllDefinitions) {
+		foreach (var definition in allDefinitions) {
 			definition.ToString(builder);
 			builder.Append(',');
 		}
@@ -35,53 +34,7 @@ public sealed class AllowedPorts {
 		return builder.ToString();
 	}
 
-	[MessagePackObject]
-	public readonly record struct PortRange(
-		[property: Key(0)] ushort FirstPort,
-		[property: Key(1)] ushort LastPort
-	) {
-		private PortRange(ushort port) : this(port, port) {}
-
-		internal bool Contains(ushort port) {
-			return port >= FirstPort && port <= LastPort;
-		}
-
-		internal void ToString(StringBuilder builder) {
-			builder.Append(FirstPort);
-
-			if (LastPort != FirstPort) {
-				builder.Append('-');
-				builder.Append(LastPort);
-			}
-		}
-
-		internal static PortRange Parse(ReadOnlySpan<char> definition) {
-			int separatorIndex = definition.IndexOf('-');
-			if (separatorIndex == -1) {
-				var port = ParsePort(definition.Trim());
-				return new PortRange(port);
-			}
-
-			var firstPort = ParsePort(definition[..separatorIndex].Trim());
-			var lastPort = ParsePort(definition[(separatorIndex + 1)..].Trim());
-			if (lastPort < firstPort) {
-				throw new FormatException("Invalid port range '" + firstPort + "-" + lastPort + "'.");
-			}
-			else {
-				return new PortRange(firstPort, lastPort);
-			}
-		}
-
-		private static ushort ParsePort(ReadOnlySpan<char> port) {
-			try {
-				return ushort.Parse(port);
-			} catch (Exception) {
-				throw new FormatException("Invalid port '" + port.ToString() + "'.");
-			}
-		}
-	}
-
-	public static AllowedPorts FromString(ReadOnlySpan<char> definitions) {
+	private static AllowedPorts FromString(ReadOnlySpan<char> definitions) {
 		List<PortRange> parsedDefinitions = new ();
 
 		while (!definitions.IsEmpty) {

Common/Phantom.Common.Data/Backups/BackupCreationResult.cs

@@ -0,0 +1,18 @@
+using MemoryPack;
+
+namespace Phantom.Common.Data.Backups;
+
+[MemoryPackable]
+public sealed partial record BackupCreationResult(
+	[property: MemoryPackOrder(0)] BackupCreationResultKind Kind,
+	[property: MemoryPackOrder(1)] BackupCreationWarnings Warnings = BackupCreationWarnings.None
+) {
+	public sealed class Builder {
+		public BackupCreationResultKind Kind { get; set; } = BackupCreationResultKind.Success;
+		public BackupCreationWarnings Warnings { get; set; }
+		
+		public BackupCreationResult Build() {
+			return new BackupCreationResult(Kind, Warnings);
+		}
+	}
+}

Common/Phantom.Common.Data/Backups/BackupCreationResultKind.cs

@@ -0,0 +1,37 @@
+namespace Phantom.Common.Data.Backups;
+
+public enum BackupCreationResultKind : byte {
+	UnknownError,
+	Success,
+	InstanceNotRunning,
+	BackupCancelled,
+	BackupAlreadyRunning,
+	BackupFileAlreadyExists,
+	CouldNotCreateBackupFolder,
+	CouldNotCopyWorldToTemporaryFolder,
+	CouldNotCreateWorldArchive
+}
+
+public static class BackupCreationResultSummaryExtensions {
+	public static bool ShouldRetry(this BackupCreationResultKind kind) {
+		return kind != BackupCreationResultKind.Success &&
+		       kind != BackupCreationResultKind.InstanceNotRunning &&
+		       kind != BackupCreationResultKind.BackupCancelled &&
+		       kind != BackupCreationResultKind.BackupAlreadyRunning &&
+		       kind != BackupCreationResultKind.BackupFileAlreadyExists;
+	}
+
+	public static string ToSentence(this BackupCreationResultKind kind) {
+		return kind switch {
+			BackupCreationResultKind.Success                            => "Backup created successfully.",
+			BackupCreationResultKind.InstanceNotRunning                 => "Instance is not running.",
+			BackupCreationResultKind.BackupCancelled                    => "Backup cancelled.",
+			BackupCreationResultKind.BackupAlreadyRunning               => "A backup is already being created.",
+			BackupCreationResultKind.BackupFileAlreadyExists            => "Backup with the same name already exists.",
+			BackupCreationResultKind.CouldNotCreateBackupFolder         => "Could not create backup folder.",
+			BackupCreationResultKind.CouldNotCopyWorldToTemporaryFolder => "Could not copy world to temporary folder.",
+			BackupCreationResultKind.CouldNotCreateWorldArchive         => "Could not create world archive.",
+			_                                                           => "Unknown error."
+		};
+	}
+}

Common/Phantom.Common.Data/Backups/BackupCreationWarnings.cs

@@ -0,0 +1,21 @@
+using System.Numerics;
+
+namespace Phantom.Common.Data.Backups;
+
+[Flags]
+public enum BackupCreationWarnings : byte {
+	None = 0,
+	CouldNotDeleteTemporaryFolder = 1 << 0,
+	CouldNotCompressWorldArchive = 1 << 1,
+	CouldNotRestoreAutomaticSaving = 1 << 2
+}
+
+public static class BackupCreationWarningsExtensions {
+	public static int Count(this BackupCreationWarnings warnings) {
+		return BitOperations.PopCount((byte) warnings);
+	}
+
+	public static IEnumerable<BackupCreationWarnings> ListFlags(this BackupCreationWarnings warnings) {
+		return Enum.GetValues<BackupCreationWarnings>().Where(warning => warning != BackupCreationWarnings.None && warnings.HasFlag(warning));
+	}
+}

Common/Phantom.Common.Data/Instance/IInstanceEvent.cs

@@ -0,0 +1,55 @@
+using MemoryPack;
+using Phantom.Common.Data.Backups;
+
+namespace Phantom.Common.Data.Instance;
+
+[MemoryPackable]
+[MemoryPackUnion(0, typeof(InstanceLaunchSuccededEvent))]
+[MemoryPackUnion(1, typeof(InstanceLaunchFailedEvent))]
+[MemoryPackUnion(2, typeof(InstanceCrashedEvent))]
+[MemoryPackUnion(3, typeof(InstanceStoppedEvent))]
+[MemoryPackUnion(4, typeof(InstanceBackupCompletedEvent))]
+public partial interface IInstanceEvent {
+	void Accept(IInstanceEventVisitor visitor);
+}
+
+[MemoryPackable]
+public sealed partial record InstanceLaunchSuccededEvent : IInstanceEvent {
+	public void Accept(IInstanceEventVisitor visitor) {
+		visitor.OnLaunchSucceeded(this);
+	}
+}
+
+[MemoryPackable]
+public sealed partial record InstanceLaunchFailedEvent([property: MemoryPackOrder(0)] InstanceLaunchFailReason Reason) : IInstanceEvent {
+	public void Accept(IInstanceEventVisitor visitor) {
+		visitor.OnLaunchFailed(this);
+	}
+}
+
+[MemoryPackable]
+public sealed partial record InstanceCrashedEvent : IInstanceEvent {
+	public void Accept(IInstanceEventVisitor visitor) {
+		visitor.OnCrashed(this);
+	}
+}
+
+[MemoryPackable]
+public sealed partial record InstanceStoppedEvent : IInstanceEvent {
+	public void Accept(IInstanceEventVisitor visitor) {
+		visitor.OnStopped(this);
+	}
+}
+
+[MemoryPackable]
+public sealed partial record InstanceBackupCompletedEvent([property: MemoryPackOrder(0)] BackupCreationResultKind Kind, [property: MemoryPackOrder(1)] BackupCreationWarnings Warnings) : IInstanceEvent {
+	public void Accept(IInstanceEventVisitor visitor) {
+		visitor.OnBackupCompleted(this);
+	}
+}
+
+public static class InstanceEvent {
+	public static readonly IInstanceEvent LaunchSucceded = new InstanceLaunchSuccededEvent();
+	public static readonly IInstanceEvent Crashed = new InstanceCrashedEvent();
+	public static readonly IInstanceEvent Stopped = new InstanceStoppedEvent();
+}

Common/Phantom.Common.Data/Instance/IInstanceEventVisitor.cs

@@ -0,0 +1,9 @@
+namespace Phantom.Common.Data.Instance; 
+
+public interface IInstanceEventVisitor {
+	void OnLaunchSucceeded(InstanceLaunchSuccededEvent e);
+	void OnLaunchFailed(InstanceLaunchFailedEvent e);
+	void OnCrashed(InstanceCrashedEvent e);
+	void OnStopped(InstanceStoppedEvent e);
+	void OnBackupCompleted(InstanceBackupCompletedEvent e);
+}

Common/Phantom.Common.Data/Instance/IInstanceStatus.cs

@@ -0,0 +1,67 @@
+using MemoryPack;
+
+namespace Phantom.Common.Data.Instance;
+
+[MemoryPackable]
+[MemoryPackUnion(0, typeof(InstanceIsOffline))]
+[MemoryPackUnion(1, typeof(InstanceIsInvalid))]
+[MemoryPackUnion(2, typeof(InstanceIsNotRunning))]
+[MemoryPackUnion(3, typeof(InstanceIsDownloading))]
+[MemoryPackUnion(4, typeof(InstanceIsLaunching))]
+[MemoryPackUnion(5, typeof(InstanceIsRunning))]
+[MemoryPackUnion(6, typeof(InstanceIsRestarting))]
+[MemoryPackUnion(7, typeof(InstanceIsStopping))]
+[MemoryPackUnion(8, typeof(InstanceIsFailed))]
+public partial interface IInstanceStatus {}
+
+[MemoryPackable]
+public sealed partial record InstanceIsOffline : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsInvalid([property: MemoryPackOrder(0)] string Reason) : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsNotRunning : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsDownloading([property: MemoryPackOrder(0)] byte Progress) : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsLaunching : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsRunning : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsRestarting : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsStopping : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsFailed([property: MemoryPackOrder(0)] InstanceLaunchFailReason Reason) : IInstanceStatus;
+
+public static class InstanceStatus {
+	public static readonly IInstanceStatus Offline = new InstanceIsOffline();
+	public static readonly IInstanceStatus NotRunning = new InstanceIsNotRunning();
+	public static readonly IInstanceStatus Launching = new InstanceIsLaunching();
+	public static readonly IInstanceStatus Running = new InstanceIsRunning();
+	public static readonly IInstanceStatus Restarting = new InstanceIsRestarting();
+	public static readonly IInstanceStatus Stopping = new InstanceIsStopping();
+	
+	public static IInstanceStatus Invalid(string reason) => new InstanceIsInvalid(reason);
+	public static IInstanceStatus Downloading(byte progress) => new InstanceIsDownloading(progress);
+	public static IInstanceStatus Failed(InstanceLaunchFailReason reason) => new InstanceIsFailed(reason);
+	
+	public static bool CanLaunch(this IInstanceStatus status) {
+		return status is InstanceIsNotRunning or InstanceIsFailed;
+	}
+
+	public static bool CanStop(this IInstanceStatus status) {
+		return status is InstanceIsDownloading or InstanceIsLaunching or InstanceIsRunning;
+	}
+
+	public static bool CanSendCommand(this IInstanceStatus status) {
+		return status is InstanceIsRunning;
+	}
+}

Common/Phantom.Common.Data/Instance/InstanceConfiguration.cs

@@ -1,18 +1,19 @@
-using MessagePack;
+using System.Collections.Immutable;
+using MemoryPack;
 using Phantom.Common.Data.Minecraft;
 
 namespace Phantom.Common.Data.Instance;
 
-[MessagePackObject]
-public sealed record InstanceConfiguration(
-	[property: Key(0)] Guid AgentGuid,
-	[property: Key(1)] Guid InstanceGuid,
-	[property: Key(2)] string InstanceName,
-	[property: Key(3)] ushort ServerPort,
-	[property: Key(4)] ushort RconPort,
-	[property: Key(5)] string MinecraftVersion,
-	[property: Key(6)] MinecraftServerKind MinecraftServerKind,
-	[property: Key(7)] RamAllocationUnits MemoryAllocation,
-	[property: Key(8)] Guid JavaRuntimeGuid,
-	[property: Key(9)] bool LaunchAutomatically
+[MemoryPackable]
+public sealed partial record InstanceConfiguration(
+	[property: MemoryPackOrder(0)] Guid AgentGuid,
+	[property: MemoryPackOrder(1)] Guid InstanceGuid,
+	[property: MemoryPackOrder(2)] string InstanceName,
+	[property: MemoryPackOrder(3)] ushort ServerPort,
+	[property: MemoryPackOrder(4)] ushort RconPort,
+	[property: MemoryPackOrder(5)] string MinecraftVersion,
+	[property: MemoryPackOrder(6)] MinecraftServerKind MinecraftServerKind,
+	[property: MemoryPackOrder(7)] RamAllocationUnits MemoryAllocation,
+	[property: MemoryPackOrder(8)] Guid JavaRuntimeGuid,
+	[property: MemoryPackOrder(9)] ImmutableArray<string> JvmArguments
 );

Common/Phantom.Common.Data/Instance/InstanceLaunchFailReason.cs

@@ -1,25 +1,33 @@
 namespace Phantom.Common.Data.Instance;
 
-public enum InstanceLaunchFailReason {
+public enum InstanceLaunchFailReason : byte {
+	UnknownError,
 	ServerPortNotAllowed,
 	ServerPortAlreadyInUse,
 	RconPortNotAllowed,
 	RconPortAlreadyInUse,
 	JavaRuntimeNotFound,
+	InvalidJvmArguments,
 	CouldNotDownloadMinecraftServer,
-	UnknownError
+	CouldNotConfigureMinecraftServer,
+	CouldNotPrepareMinecraftServerLauncher,
+	CouldNotStartMinecraftServer
 }
 
 public static class InstanceLaunchFailReasonExtensions {
 	public static string ToSentence(this InstanceLaunchFailReason reason) {
 		return reason switch {
-			InstanceLaunchFailReason.ServerPortNotAllowed            => "Server port not allowed.",
-			InstanceLaunchFailReason.ServerPortAlreadyInUse          => "Server port already in use.",
-			InstanceLaunchFailReason.RconPortNotAllowed              => "Rcon port not allowed.",
-			InstanceLaunchFailReason.RconPortAlreadyInUse            => "Rcon port already in use.",
-			InstanceLaunchFailReason.JavaRuntimeNotFound             => "Java runtime not found.",
-			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer => "Could not download Minecraft server.",
-			_                                                        => "Unknown error."
+			InstanceLaunchFailReason.ServerPortNotAllowed                   => "Server port not allowed.",
+			InstanceLaunchFailReason.ServerPortAlreadyInUse                 => "Server port already in use.",
+			InstanceLaunchFailReason.RconPortNotAllowed                     => "Rcon port not allowed.",
+			InstanceLaunchFailReason.RconPortAlreadyInUse                   => "Rcon port already in use.",
+			InstanceLaunchFailReason.JavaRuntimeNotFound                    => "Java runtime not found.",
+			InstanceLaunchFailReason.InvalidJvmArguments                    => "Invalid JVM arguments.",
+			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer        => "Could not download Minecraft server.",
+			InstanceLaunchFailReason.CouldNotConfigureMinecraftServer       => "Could not configure Minecraft server.",
+			InstanceLaunchFailReason.CouldNotPrepareMinecraftServerLauncher => "Could not prepare Minecraft server launcher.",
+			InstanceLaunchFailReason.CouldNotStartMinecraftServer           => "Could not start Minecraft server.",
+			_                                                               => "Unknown error."
 		};
 	}
 }

Common/Phantom.Common.Data/Instance/InstanceLaunchProperties.cs

@@ -0,0 +1,9 @@
+using MemoryPack;
+using Phantom.Common.Data.Minecraft;
+
+namespace Phantom.Common.Data.Instance; 
+
+[MemoryPackable]
+public sealed partial record InstanceLaunchProperties(
+	[property: MemoryPackOrder(0)] FileDownloadInfo? ServerDownloadInfo
+);

Common/Phantom.Common.Data/Instance/InstanceStatus.cs

@@ -1,63 +0,0 @@
-using MessagePack;
-
-namespace Phantom.Common.Data.Instance;
-
-[Union(0, typeof(Offline))]
-[Union(1, typeof(Invalid))]
-[Union(2, typeof(NotRunning))]
-[Union(3, typeof(Downloading))]
-[Union(4, typeof(Launching))]
-[Union(5, typeof(Running))]
-[Union(6, typeof(Stopping))]
-[Union(7, typeof(Failed))]
-public abstract record InstanceStatus {
-	public static readonly InstanceStatus IsOffline = new Offline();
-	public static readonly InstanceStatus IsNotRunning = new NotRunning();
-	public static readonly InstanceStatus IsLaunching = new Launching();
-	public static readonly InstanceStatus IsRunning = new Running();
-	public static readonly InstanceStatus IsStopping = new Stopping();
-
-	[MessagePackObject]
-	public sealed record Offline : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Invalid(
-		[property: Key(0)] string Reason
-	) : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record NotRunning : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Downloading(
-		[property: Key(0)] byte Progress
-	) : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Launching : InstanceStatus;
-	
-	[MessagePackObject]
-	public sealed record Running : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Stopping : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Failed(
-		[property: Key(0)] InstanceLaunchFailReason Reason
-	) : InstanceStatus;
-}
-
-public static class InstanceStatusExtensions {
-	public static bool CanLaunch(this InstanceStatus status) {
-		return status is InstanceStatus.NotRunning or InstanceStatus.Failed;
-	}
-
-	public static bool CanStop(this InstanceStatus status) {
-		return status is InstanceStatus.Downloading or InstanceStatus.Launching or InstanceStatus.Running;
-	}
-
-	public static bool CanSendCommand(this InstanceStatus status) {
-		return status is InstanceStatus.Running;
-	}
-}

Common/Phantom.Common.Data/Java/JavaRuntime.cs

@@ -1,13 +1,13 @@
 using System.Diagnostics.CodeAnalysis;
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data.Java;
 
-[MessagePackObject]
-public sealed record JavaRuntime(
-	[property: Key(0)] string MainVersion,
-	[property: Key(1)] string FullVersion,
-	[property: Key(2)] string DisplayName
+[MemoryPackable]
+public sealed partial record JavaRuntime(
+	[property: MemoryPackOrder(0)] string MainVersion,
+	[property: MemoryPackOrder(1)] string FullVersion,
+	[property: MemoryPackOrder(2)] string DisplayName
 ) : IComparable<JavaRuntime> {
 	public int CompareTo(JavaRuntime? other) {
 		if (ReferenceEquals(this, other)) {

Common/Phantom.Common.Data/Java/TaggedJavaRuntime.cs

@@ -1,9 +1,9 @@
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data.Java; 
 
-[MessagePackObject]
-public sealed record TaggedJavaRuntime(
-	[property: Key(0)] Guid Guid,
-	[property: Key(1)] JavaRuntime Runtime
+[MemoryPackable]
+public sealed partial record TaggedJavaRuntime(
+	[property: MemoryPackOrder(0)] Guid Guid,
+	[property: MemoryPackOrder(1)] JavaRuntime Runtime
 );

Common/Phantom.Common.Data/Minecraft/FileDownloadInfo.cs

@@ -0,0 +1,30 @@
+using MemoryPack;
+using Phantom.Utils.Cryptography;
+using Phantom.Utils.IO;
+
+namespace Phantom.Common.Data.Minecraft; 
+
+[MemoryPackable]
+public sealed partial class FileDownloadInfo {
+	[MemoryPackOrder(0)]
+	public string DownloadUrl { get; }
+	
+	[MemoryPackOrder(1)]
+	[MemoryPackInclude]
+	private readonly string hash;
+	
+	[MemoryPackIgnore]
+	public Sha1String Hash => Sha1String.FromString(hash);
+	
+	[MemoryPackOrder(2)]
+	public FileSize Size { get; }
+	
+	public FileDownloadInfo(string downloadUrl, Sha1String hash, FileSize size) : this(downloadUrl, hash.ToString(), size) {}
+
+	[MemoryPackConstructor]
+	private FileDownloadInfo(string downloadUrl, string hash, FileSize size) {
+		this.DownloadUrl = downloadUrl;
+		this.hash = hash;
+		this.Size = size;
+	}
+}

Common/Phantom.Common.Data/Minecraft/MinecraftServerKind.cs

@@ -1,5 +1,6 @@
 namespace Phantom.Common.Data.Minecraft; 
 
 public enum MinecraftServerKind : ushort {
-	Vanilla = 1
+	Vanilla = 1,
+	Fabric = 2
 }

Common/Phantom.Common.Data/Minecraft/MinecraftStopStrategy.cs

@@ -0,0 +1,10 @@
+using MemoryPack;
+
+namespace Phantom.Common.Data.Minecraft;
+
+[MemoryPackable]
+public readonly partial record struct MinecraftStopStrategy(
+	[property: MemoryPackOrder(0)] ushort Seconds
+) {
+	public static MinecraftStopStrategy Instant => new (0);
+}

Common/Phantom.Common.Data/Minecraft/MinecraftVersion.cs

@@ -0,0 +1,7 @@
+namespace Phantom.Common.Data.Minecraft; 
+
+public sealed record MinecraftVersion(
+	string Id,
+	MinecraftVersionType Type,
+	string MetadataUrl
+);

Common/Phantom.Common.Data/Minecraft/MinecraftVersionType.cs

@@ -0,0 +1,38 @@
+using System.Collections.Immutable;
+
+namespace Phantom.Common.Data.Minecraft;
+
+public enum MinecraftVersionType : ushort {
+	Other = 0,
+	Release = 1,
+	Snapshot = 2,
+	OldBeta = 3,
+	OldAlpha = 4
+}
+
+public static class MinecraftVersionTypes {
+	public static readonly ImmutableArray<MinecraftVersionType> WithServerJars = ImmutableArray.Create(
+		MinecraftVersionType.Release,
+		MinecraftVersionType.Snapshot
+	);
+
+	public static MinecraftVersionType FromString(string? type) {
+		return type switch {
+			"release"   => MinecraftVersionType.Release,
+			"snapshot"  => MinecraftVersionType.Snapshot,
+			"old_beta"  => MinecraftVersionType.OldBeta,
+			"old_alpha" => MinecraftVersionType.OldAlpha,
+			_           => MinecraftVersionType.Other
+		};
+	}
+
+	public static string ToNiceNamePlural(this MinecraftVersionType type) {
+		return type switch {
+			MinecraftVersionType.Release  => "Releases",
+			MinecraftVersionType.Snapshot => "Snapshots",
+			MinecraftVersionType.OldBeta  => "Beta",
+			MinecraftVersionType.OldAlpha => "Alpha",
+			_                             => "Unknown"
+		};
+	}
+}

Common/Phantom.Common.Data/Phantom.Common.Data.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
   
   <ItemGroup>
-    <PackageReference Include="MessagePack.Annotations" Version="2.4.35" />
+    <PackageReference Include="MemoryPack" />
   </ItemGroup>
   
   <ItemGroup>

Common/Phantom.Common.Data/PortRange.cs

@@ -0,0 +1,48 @@
+using System.Text;
+using MemoryPack;
+
+namespace Phantom.Common.Data;
+
+[MemoryPackable]
+readonly partial record struct PortRange(
+	[property: MemoryPackOrder(0)] ushort FirstPort,
+	[property: MemoryPackOrder(1)] ushort LastPort
+) {
+	internal bool Contains(ushort port) {
+		return port >= FirstPort && port <= LastPort;
+	}
+
+	internal void ToString(StringBuilder builder) {
+		builder.Append(FirstPort);
+
+		if (LastPort != FirstPort) {
+			builder.Append('-');
+			builder.Append(LastPort);
+		}
+	}
+
+	internal static PortRange Parse(ReadOnlySpan<char> definition) {
+		int separatorIndex = definition.IndexOf('-');
+		if (separatorIndex == -1) {
+			var port = ParsePort(definition.Trim());
+			return new PortRange(port, port);
+		}
+
+		var firstPort = ParsePort(definition[..separatorIndex].Trim());
+		var lastPort = ParsePort(definition[(separatorIndex + 1)..].Trim());
+		if (lastPort < firstPort) {
+			throw new FormatException("Invalid port range '" + firstPort + "-" + lastPort + "'.");
+		}
+		else {
+			return new PortRange(firstPort, lastPort);
+		}
+	}
+
+	private static ushort ParsePort(ReadOnlySpan<char> port) {
+		try {
+			return ushort.Parse(port);
+		} catch (Exception) {
+			throw new FormatException("Invalid port '" + port.ToString() + "'.");
+		}
+	}
+}

Common/Phantom.Common.Data/RamAllocationUnits.cs

@@ -1,17 +1,17 @@
 using System.Diagnostics.CodeAnalysis;
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data;
 
 /// <summary>
 /// Represents a number of RAM allocation units, using the conversion factor of 256 MB per unit. Supports allocations up to 16 TB minus 256 MB (65535 units).
 /// </summary>
-[MessagePackObject]
+[MemoryPackable]
 [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
-public readonly record struct RamAllocationUnits(
-	[property: Key(0)] ushort RawValue
+public readonly partial record struct RamAllocationUnits(
+	[property: MemoryPackOrder(0)] ushort RawValue
 ) : IComparable<RamAllocationUnits> {
-	[IgnoreMember]
+	[MemoryPackIgnore]
 	public uint InMegabytes => (uint) RawValue * MegabytesPerUnit;
 
 	public int CompareTo(RamAllocationUnits other) {

Common/Phantom.Common.Data/Replies/ConfigureInstanceResult.cs

@@ -1,8 +1,5 @@
 namespace Phantom.Common.Data.Replies; 
 
-public enum ConfigureInstanceResult {
-	Success,
-	AgentShuttingDown,
-	InstanceLimitExceeded,
-	MemoryLimitExceeded
+public enum ConfigureInstanceResult : byte {
+	Success
 }

Common/Phantom.Common.Data/Replies/InstanceActionGeneralResult.cs

@@ -0,0 +1,8 @@
+namespace Phantom.Common.Data.Replies;
+
+public enum InstanceActionGeneralResult : byte {
+	None,
+	AgentShuttingDown,
+	AgentIsNotResponding,
+	InstanceDoesNotExist
+}

Common/Phantom.Common.Data/Replies/InstanceActionResult.cs

@@ -0,0 +1,41 @@
+using MemoryPack;
+
+namespace Phantom.Common.Data.Replies;
+
+[MemoryPackable]
+public sealed partial record InstanceActionResult<T>(
+	[property: MemoryPackOrder(0)] InstanceActionGeneralResult GeneralResult,
+	[property: MemoryPackOrder(1)] T? ConcreteResult
+) {
+	public bool Is(T? concreteResult) {
+		return GeneralResult == InstanceActionGeneralResult.None && EqualityComparer<T>.Default.Equals(ConcreteResult, concreteResult);
+	}
+
+	public InstanceActionResult<T2> Map<T2>(Func<T, T2> mapper) {
+		return new InstanceActionResult<T2>(GeneralResult, ConcreteResult is not null ? mapper(ConcreteResult) : default);
+	}
+
+	public string ToSentence(Func<T, string> concreteResultToSentence) {
+		return GeneralResult switch {
+			InstanceActionGeneralResult.None                 => concreteResultToSentence(ConcreteResult!),
+			InstanceActionGeneralResult.AgentShuttingDown    => "Agent is shutting down.",
+			InstanceActionGeneralResult.AgentIsNotResponding => "Agent is not responding.",
+			InstanceActionGeneralResult.InstanceDoesNotExist => "Instance does not exist.",
+			_                                                => "Unknown result."
+		};
+	}
+}
+
+public static class InstanceActionResult {
+	public static InstanceActionResult<T> General<T>(InstanceActionGeneralResult generalResult) {
+		return new InstanceActionResult<T>(generalResult, default);
+	}
+
+	public static InstanceActionResult<T> Concrete<T>(T? concreteResult) {
+		return new InstanceActionResult<T>(InstanceActionGeneralResult.None, concreteResult);
+	}
+
+	public static InstanceActionResult<T> DidNotReplyIfNull<T>(this InstanceActionResult<T>? result) {
+		return result ?? General<T>(InstanceActionGeneralResult.AgentIsNotResponding);
+	}
+}

Common/Phantom.Common.Data/Replies/LaunchInstanceResult.cs

@@ -1,26 +1,24 @@
 namespace Phantom.Common.Data.Replies;
 
-public enum LaunchInstanceResult {
+public enum LaunchInstanceResult : byte {
+	UnknownError,
 	LaunchInitiated,
-	AgentShuttingDown,
-	InstanceDoesNotExist,
 	InstanceAlreadyLaunching,
 	InstanceAlreadyRunning,
 	InstanceIsStopping,
-	CommunicationError,
-	UnknownError
+	InstanceLimitExceeded,
+	MemoryLimitExceeded
 }
 
 public static class LaunchInstanceResultExtensions {
 	public static string ToSentence(this LaunchInstanceResult reason) {
 		return reason switch {
 			LaunchInstanceResult.LaunchInitiated          => "Launch initiated.",
-			LaunchInstanceResult.AgentShuttingDown        => "Agent is shutting down.",
-			LaunchInstanceResult.InstanceDoesNotExist     => "Instance does not exist.",
 			LaunchInstanceResult.InstanceAlreadyLaunching => "Instance is already launching.",
 			LaunchInstanceResult.InstanceAlreadyRunning   => "Instance is already running.",
 			LaunchInstanceResult.InstanceIsStopping       => "Instance is stopping.",
-			LaunchInstanceResult.CommunicationError       => "Communication error.",
+			LaunchInstanceResult.InstanceLimitExceeded    => "Agent does not have any more available instances.",
+			LaunchInstanceResult.MemoryLimitExceeded      => "Agent does not have enough available memory.",
 			_                                             => "Unknown error."
 		};
 	}

Common/Phantom.Common.Data/Replies/SendCommandToInstanceResult.cs

@@ -1,21 +1,15 @@
 namespace Phantom.Common.Data.Replies;
 
-public enum SendCommandToInstanceResult {
-	Success,
-	InstanceDoesNotExist,
-	AgentShuttingDown,
-	AgentCommunicationError,
-	UnknownError
+public enum SendCommandToInstanceResult : byte {
+	UnknownError,
+	Success
 }
 
 public static class SendCommandToInstanceResultExtensions {
 	public static string ToSentence(this SendCommandToInstanceResult reason) {
 		return reason switch {
-			SendCommandToInstanceResult.Success                 => "Command sent.",
-			SendCommandToInstanceResult.InstanceDoesNotExist    => "Instance does not exist.",
-			SendCommandToInstanceResult.AgentShuttingDown       => "Agent is shutting down.",
-			SendCommandToInstanceResult.AgentCommunicationError => "Agent did not reply in time.",
-			_                                                   => "Unknown error."
+			SendCommandToInstanceResult.Success => "Command sent.",
+			_                                   => "Unknown error."
 		};
 	}
 }

Common/Phantom.Common.Data/Replies/StopInstanceResult.cs

@@ -1,24 +1,18 @@
 namespace Phantom.Common.Data.Replies;
 
-public enum StopInstanceResult {
+public enum StopInstanceResult : byte {
+	UnknownError,
 	StopInitiated,
-	AgentShuttingDown,
-	InstanceDoesNotExist,
 	InstanceAlreadyStopping,
-	InstanceAlreadyStopped,
-	CommunicationError,
-	UnknownError
+	InstanceAlreadyStopped
 }
 
 public static class StopInstanceResultExtensions {
 	public static string ToSentence(this StopInstanceResult reason) {
 		return reason switch {
 			StopInstanceResult.StopInitiated           => "Stopping initiated.",
-			StopInstanceResult.AgentShuttingDown       => "Agent is shutting down.",
-			StopInstanceResult.InstanceDoesNotExist    => "Instance does not exist.",
 			StopInstanceResult.InstanceAlreadyStopping => "Instance is already stopping.",
 			StopInstanceResult.InstanceAlreadyStopped  => "Instance is already stopped.",
-			StopInstanceResult.CommunicationError      => "Communication error.",
 			_                                          => "Unknown error."
 		};
 	}