Add 'meshmc/' from commit 'fad6a1066616b69d7f5fef01178efdf014c59537'

git-subtree-dir: meshmc
git-subtree-mainline: 934382c8a1ce738589dee9ee0f14e1cec812770e
git-subtree-split: fad6a1066616b69d7f5fef01178efdf014c59537

22 files changed, 2218 insertions, 0 deletions

diff --git a/meshmc/launcher/minecraft/launch/ClaimAccount.cpp b/meshmc/launcher/minecraft/launch/ClaimAccount.cpp
new file mode 100644
index 0000000000..a1ed6fdb69
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ClaimAccount.cpp
@@ -0,0 +1,49 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "ClaimAccount.h"
+#include <launch/LaunchTask.h>
+
+#include "Application.h"
+#include "minecraft/auth/AccountList.h"
+
+ClaimAccount::ClaimAccount(LaunchTask* parent, AuthSessionPtr session)
+	: LaunchStep(parent)
+{
+	if (session->status == AuthSession::Status::PlayableOnline &&
+		!session->demo) {
+		auto accounts = APPLICATION->accounts();
+		m_account = accounts->getAccountByProfileName(session->player_name);
+	}
+}
+
+void ClaimAccount::executeTask()
+{
+	if (m_account) {
+		lock.reset(new UseLock(m_account));
+		emitSucceeded();
+	}
+}
+
+void ClaimAccount::finalize()
+{
+	lock.reset();
+}
diff --git a/meshmc/launcher/minecraft/launch/ClaimAccount.h b/meshmc/launcher/minecraft/launch/ClaimAccount.h
new file mode 100644
index 0000000000..d3f64bd8ed
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ClaimAccount.h
@@ -0,0 +1,61 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <minecraft/auth/MinecraftAccount.h>
+
+class ClaimAccount : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit ClaimAccount(LaunchTask* parent, AuthSessionPtr session);
+	virtual ~ClaimAccount() {};
+
+	void executeTask() override;
+	void finalize() override;
+	bool canAbort() const override
+	{
+		return false;
+	}
+
+  private:
+	std::unique_ptr<UseLock> lock;
+	MinecraftAccountPtr m_account;
+};
diff --git a/meshmc/launcher/minecraft/launch/CreateGameFolders.cpp b/meshmc/launcher/minecraft/launch/CreateGameFolders.cpp
new file mode 100644
index 0000000000..32cd010905
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/CreateGameFolders.cpp
@@ -0,0 +1,50 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "CreateGameFolders.h"
+#include "minecraft/MinecraftInstance.h"
+#include "launch/LaunchTask.h"
+#include "FileSystem.h"
+
+CreateGameFolders::CreateGameFolders(LaunchTask* parent) : LaunchStep(parent) {}
+
+void CreateGameFolders::executeTask()
+{
+	auto instance = m_parent->instance();
+	std::shared_ptr<MinecraftInstance> minecraftInstance =
+		std::dynamic_pointer_cast<MinecraftInstance>(instance);
+
+	if (!FS::ensureFolderPathExists(minecraftInstance->gameRoot())) {
+		emit logLine("Couldn't create the main game folder",
+					 MessageLevel::Error);
+		emitFailed(tr("Couldn't create the main game folder"));
+		return;
+	}
+
+	// HACK: this is a workaround for MCL-3732 - 'server-resource-packs' folder
+	// is created.
+	if (!FS::ensureFolderPathExists(FS::PathCombine(
+			minecraftInstance->gameRoot(), "server-resource-packs"))) {
+		emit logLine("Couldn't create the 'server-resource-packs' folder",
+					 MessageLevel::Error);
+	}
+	emitSucceeded();
+}
diff --git a/meshmc/launcher/minecraft/launch/CreateGameFolders.h b/meshmc/launcher/minecraft/launch/CreateGameFolders.h
new file mode 100644
index 0000000000..76a9225c21
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/CreateGameFolders.h
@@ -0,0 +1,58 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <LoggedProcess.h>
+#include <minecraft/auth/AuthSession.h>
+
+// Create the main .minecraft for the instance and any other necessary folders
+class CreateGameFolders : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit CreateGameFolders(LaunchTask* parent);
+	virtual ~CreateGameFolders() {};
+
+	virtual void executeTask();
+	virtual bool canAbort() const
+	{
+		return false;
+	}
+};
diff --git a/meshmc/launcher/minecraft/launch/DirectJavaLaunch.cpp b/meshmc/launcher/minecraft/launch/DirectJavaLaunch.cpp
new file mode 100644
index 0000000000..c1dc249eac
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/DirectJavaLaunch.cpp
@@ -0,0 +1,173 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "DirectJavaLaunch.h"
+#include <launch/LaunchTask.h>
+#include <minecraft/MinecraftInstance.h>
+#include <FileSystem.h>
+#include <Commandline.h>
+#include <QStandardPaths>
+
+DirectJavaLaunch::DirectJavaLaunch(LaunchTask* parent) : LaunchStep(parent)
+{
+	connect(&m_process, &LoggedProcess::log, this, &DirectJavaLaunch::logLines);
+	connect(&m_process, &LoggedProcess::stateChanged, this,
+			&DirectJavaLaunch::on_state);
+}
+
+void DirectJavaLaunch::executeTask()
+{
+	auto instance = m_parent->instance();
+	std::shared_ptr<MinecraftInstance> minecraftInstance =
+		std::dynamic_pointer_cast<MinecraftInstance>(instance);
+	QStringList args = minecraftInstance->javaArguments();
+
+	args.append("-Djava.library.path=" + minecraftInstance->getNativePath());
+
+	auto classPathEntries = minecraftInstance->getClassPath();
+	args.append("-cp");
+	QString classpath;
+#ifdef Q_OS_WIN32
+	classpath = classPathEntries.join(';');
+#else
+	classpath = classPathEntries.join(':');
+#endif
+	args.append(classpath);
+	args.append(minecraftInstance->getMainClass());
+
+	QString allArgs = args.join(", ");
+	emit logLine("Java Arguments:\n[" + m_parent->censorPrivateInfo(allArgs) +
+					 "]\n\n",
+				 MessageLevel::MeshMC);
+
+	auto javaPath =
+		FS::ResolveExecutable(instance->settings()->get("JavaPath").toString());
+
+	m_process.setProcessEnvironment(instance->createEnvironment());
+
+	// make detachable - this will keep the process running even if the object
+	// is destroyed
+	m_process.setDetachable(true);
+
+	auto mcArgs =
+		minecraftInstance->processMinecraftArgs(m_session, m_serverToJoin);
+	args.append(mcArgs);
+
+	QString wrapperCommandStr = instance->getWrapperCommand().trimmed();
+	if (!wrapperCommandStr.isEmpty()) {
+		auto wrapperArgs = Commandline::splitArgs(wrapperCommandStr);
+		auto wrapperCommand = wrapperArgs.takeFirst();
+		auto realWrapperCommand =
+			QStandardPaths::findExecutable(wrapperCommand);
+		if (realWrapperCommand.isEmpty()) {
+			const char* reason =
+				QT_TR_NOOP("The wrapper command \"%1\" couldn't be found.");
+			emit logLine(QString(reason).arg(wrapperCommand),
+						 MessageLevel::Fatal);
+			emitFailed(tr(reason).arg(wrapperCommand));
+			return;
+		}
+		emit logLine("Wrapper command is:\n" + wrapperCommandStr + "\n\n",
+					 MessageLevel::MeshMC);
+		args.prepend(javaPath);
+		m_process.start(wrapperCommand, wrapperArgs + args);
+	} else {
+		m_process.start(javaPath, args);
+	}
+}
+
+void DirectJavaLaunch::on_state(LoggedProcess::State state)
+{
+	switch (state) {
+		case LoggedProcess::FailedToStart: {
+			//: Error message displayed if instance can't start
+			const char* reason = QT_TR_NOOP("Could not launch minecraft!");
+			emit logLine(reason, MessageLevel::Fatal);
+			emitFailed(tr(reason));
+			return;
+		}
+		case LoggedProcess::Aborted:
+		case LoggedProcess::Crashed: {
+			m_parent->setPid(-1);
+			emitFailed(tr("Game crashed."));
+			return;
+		}
+		case LoggedProcess::Finished: {
+			m_parent->setPid(-1);
+			// if the exit code wasn't 0, report this as a crash
+			auto exitCode = m_process.exitCode();
+			if (exitCode != 0) {
+				emitFailed(tr("Game crashed."));
+				return;
+			}
+			// FIXME: make this work again
+			//  m_postlaunchprocess.processEnvironment().insert("INST_EXITCODE",
+			//  QString(exitCode)); run post-exit
+			emitSucceeded();
+			break;
+		}
+		case LoggedProcess::Running:
+			emit logLine(QString("Minecraft process ID: %1\n\n")
+							 .arg(m_process.processId()),
+						 MessageLevel::MeshMC);
+			m_parent->setPid(m_process.processId());
+			m_parent->instance()->setLastLaunch();
+			break;
+		default:
+			break;
+	}
+}
+
+void DirectJavaLaunch::setWorkingDirectory(const QString& wd)
+{
+	m_process.setWorkingDirectory(wd);
+}
+
+void DirectJavaLaunch::proceed()
+{
+	// nil
+}
+
+bool DirectJavaLaunch::abort()
+{
+	auto state = m_process.state();
+	if (state == LoggedProcess::Running || state == LoggedProcess::Starting) {
+		m_process.kill();
+	}
+	return true;
+}
diff --git a/meshmc/launcher/minecraft/launch/DirectJavaLaunch.h b/meshmc/launcher/minecraft/launch/DirectJavaLaunch.h
new file mode 100644
index 0000000000..f696e999ea
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/DirectJavaLaunch.h
@@ -0,0 +1,80 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <LoggedProcess.h>
+#include <minecraft/auth/AuthSession.h>
+
+#include "MinecraftServerTarget.h"
+
+class DirectJavaLaunch : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit DirectJavaLaunch(LaunchTask* parent);
+	virtual ~DirectJavaLaunch() {};
+
+	virtual void executeTask();
+	virtual bool abort();
+	virtual void proceed();
+	virtual bool canAbort() const
+	{
+		return true;
+	}
+	void setWorkingDirectory(const QString& wd);
+	void setAuthSession(AuthSessionPtr session)
+	{
+		m_session = session;
+	}
+
+	void setServerToJoin(MinecraftServerTargetPtr serverToJoin)
+	{
+		m_serverToJoin = std::move(serverToJoin);
+	}
+
+  private slots:
+	void on_state(LoggedProcess::State state);
+
+  private:
+	LoggedProcess m_process;
+	QString m_command;
+	AuthSessionPtr m_session;
+	MinecraftServerTargetPtr m_serverToJoin;
+};
diff --git a/meshmc/launcher/minecraft/launch/ExtractNatives.cpp b/meshmc/launcher/minecraft/launch/ExtractNatives.cpp
new file mode 100644
index 0000000000..706820468b
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ExtractNatives.cpp
@@ -0,0 +1,133 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ExtractNatives.h"
+#include <minecraft/MinecraftInstance.h>
+#include <launch/LaunchTask.h>
+
+#include "MMCZip.h"
+#include "FileSystem.h"
+#include <QDir>
+
+#ifdef major
+#undef major
+#endif
+#ifdef minor
+#undef minor
+#endif
+
+static QString replaceSuffix(QString target, const QString& suffix,
+							 const QString& replacement)
+{
+	if (!target.endsWith(suffix)) {
+		return target;
+	}
+	target.resize(target.length() - suffix.length());
+	return target + replacement;
+}
+
+static bool unzipNatives(QString source, QString targetFolder,
+						 bool applyJnilibHack, bool nativeOpenAL,
+						 bool nativeGLFW)
+{
+	QDir directory(targetFolder);
+	QStringList entries = MMCZip::listEntries(source);
+	if (entries.isEmpty()) {
+		return false;
+	}
+	for (const auto& name : entries) {
+		auto lowercase = name.toLower();
+		if (nativeGLFW && name.contains("glfw")) {
+			continue;
+		}
+		if (nativeOpenAL && name.contains("openal")) {
+			continue;
+		}
+		// Skip directories
+		if (name.endsWith('/'))
+			continue;
+
+		QString outName = name;
+		if (applyJnilibHack) {
+			outName = replaceSuffix(outName, ".jnilib", ".dylib");
+		}
+		QString absFilePath = directory.absoluteFilePath(outName);
+		if (!MMCZip::extractRelFile(source, name, absFilePath)) {
+			return false;
+		}
+	}
+	return true;
+}
+
+void ExtractNatives::executeTask()
+{
+	auto instance = m_parent->instance();
+	std::shared_ptr<MinecraftInstance> minecraftInstance =
+		std::dynamic_pointer_cast<MinecraftInstance>(instance);
+	auto toExtract = minecraftInstance->getNativeJars();
+	if (toExtract.isEmpty()) {
+		emitSucceeded();
+		return;
+	}
+	auto settings = minecraftInstance->settings();
+	bool nativeOpenAL = settings->get("UseNativeOpenAL").toBool();
+	bool nativeGLFW = settings->get("UseNativeGLFW").toBool();
+
+	auto outputPath = minecraftInstance->getNativePath();
+	auto javaVersion = minecraftInstance->getJavaVersion();
+	bool jniHackEnabled = javaVersion.major() >= 8;
+	for (const auto& source : toExtract) {
+		if (!unzipNatives(source, outputPath, jniHackEnabled, nativeOpenAL,
+						  nativeGLFW)) {
+			const char* reason = QT_TR_NOOP(
+				"Couldn't extract native jar '%1' to destination '%2'");
+			emit logLine(QString(reason).arg(source, outputPath),
+						 MessageLevel::Fatal);
+			emitFailed(tr(reason).arg(source, outputPath));
+		}
+	}
+	emitSucceeded();
+}
+
+void ExtractNatives::finalize()
+{
+	auto instance = m_parent->instance();
+	QString target_dir = FS::PathCombine(instance->instanceRoot(), "natives/");
+	QDir dir(target_dir);
+	dir.removeRecursively();
+}
diff --git a/meshmc/launcher/minecraft/launch/ExtractNatives.h b/meshmc/launcher/minecraft/launch/ExtractNatives.h
new file mode 100644
index 0000000000..0550603f7e
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ExtractNatives.h
@@ -0,0 +1,59 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <memory>
+#include "minecraft/auth/AuthSession.h"
+
+// FIXME: temporary wrapper for existing task.
+class ExtractNatives : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit ExtractNatives(LaunchTask* parent) : LaunchStep(parent) {};
+	virtual ~ExtractNatives() {};
+
+	void executeTask() override;
+	bool canAbort() const override
+	{
+		return false;
+	}
+	void finalize() override;
+};
diff --git a/meshmc/launcher/minecraft/launch/MeshMCPartLaunch.cpp b/meshmc/launcher/minecraft/launch/MeshMCPartLaunch.cpp
new file mode 100644
index 0000000000..83f8c4436d
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/MeshMCPartLaunch.cpp
@@ -0,0 +1,237 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "MeshMCPartLaunch.h"
+
+#include <QStandardPaths>
+
+#include "launch/LaunchTask.h"
+#include "minecraft/MinecraftInstance.h"
+#include "FileSystem.h"
+#include "Commandline.h"
+#include "Application.h"
+
+MeshMCPartLaunch::MeshMCPartLaunch(LaunchTask* parent) : LaunchStep(parent)
+{
+	connect(&m_process, &LoggedProcess::log, this, &MeshMCPartLaunch::logLines);
+	connect(&m_process, &LoggedProcess::stateChanged, this,
+			&MeshMCPartLaunch::on_state);
+}
+
+#ifdef Q_OS_WIN
+// returns 8.3 file format from long path
+#include <windows.h>
+QString shortPathName(const QString& file)
+{
+	auto input = file.toStdWString();
+	std::wstring output;
+	long length = GetShortPathNameW(input.c_str(), NULL, 0);
+	// NOTE: this resizing might seem weird...
+	// when GetShortPathNameW fails, it returns length including null character
+	// when it succeeds, it returns length excluding null character
+	// See:
+	// https://msdn.microsoft.com/en-us/library/windows/desktop/aa364989(v=vs.85).aspx
+	output.resize(length);
+	GetShortPathNameW(input.c_str(), (LPWSTR)output.c_str(), length);
+	output.resize(length - 1);
+	QString ret = QString::fromStdWString(output);
+	return ret;
+}
+#endif
+
+// if the string survives roundtrip through local 8bit encoding...
+bool fitsInLocal8bit(const QString& string)
+{
+	return string == QString::fromLocal8Bit(string.toLocal8Bit());
+}
+
+void MeshMCPartLaunch::executeTask()
+{
+	auto instance = m_parent->instance();
+	std::shared_ptr<MinecraftInstance> minecraftInstance =
+		std::dynamic_pointer_cast<MinecraftInstance>(instance);
+
+	m_launchScript =
+		minecraftInstance->createLaunchScript(m_session, m_serverToJoin);
+	QStringList args = minecraftInstance->javaArguments();
+	QString allArgs = args.join(", ");
+	emit logLine("Java Arguments:\n[" + m_parent->censorPrivateInfo(allArgs) +
+					 "]\n\n",
+				 MessageLevel::MeshMC);
+
+	auto javaPath =
+		FS::ResolveExecutable(instance->settings()->get("JavaPath").toString());
+
+	m_process.setProcessEnvironment(instance->createEnvironment());
+
+	// make detachable - this will keep the process running even if the object
+	// is destroyed
+	m_process.setDetachable(true);
+
+	auto classPath = minecraftInstance->getClassPath();
+	classPath.prepend(
+		FS::PathCombine(APPLICATION->getJarsPath(), "NewLaunch.jar"));
+
+	auto natPath = minecraftInstance->getNativePath();
+#ifdef Q_OS_WIN
+	if (!fitsInLocal8bit(natPath)) {
+		args << "-Djava.library.path=" + shortPathName(natPath);
+	} else {
+		args << "-Djava.library.path=" + natPath;
+	}
+#else
+	args << "-Djava.library.path=" + natPath;
+#endif
+
+	args << "-cp";
+#ifdef Q_OS_WIN
+	QStringList processed;
+	for (auto& item : classPath) {
+		if (!fitsInLocal8bit(item)) {
+			processed << shortPathName(item);
+		} else {
+			processed << item;
+		}
+	}
+	args << processed.join(';');
+#else
+	args << classPath.join(':');
+#endif
+	args << "org.projecttick.EntryPoint";
+
+	qDebug() << args.join(' ');
+
+	QString wrapperCommandStr = instance->getWrapperCommand().trimmed();
+	if (!wrapperCommandStr.isEmpty()) {
+		auto wrapperArgs = Commandline::splitArgs(wrapperCommandStr);
+		auto wrapperCommand = wrapperArgs.takeFirst();
+		auto realWrapperCommand =
+			QStandardPaths::findExecutable(wrapperCommand);
+		if (realWrapperCommand.isEmpty()) {
+			const char* reason =
+				QT_TR_NOOP("The wrapper command \"%1\" couldn't be found.");
+			emit logLine(QString(reason).arg(wrapperCommand),
+						 MessageLevel::Fatal);
+			emitFailed(tr(reason).arg(wrapperCommand));
+			return;
+		}
+		emit logLine("Wrapper command is:\n" + wrapperCommandStr + "\n\n",
+					 MessageLevel::MeshMC);
+		args.prepend(javaPath);
+		m_process.start(wrapperCommand, wrapperArgs + args);
+	} else {
+		m_process.start(javaPath, args);
+	}
+}
+
+void MeshMCPartLaunch::on_state(LoggedProcess::State state)
+{
+	switch (state) {
+		case LoggedProcess::FailedToStart: {
+			//: Error message displayed if instace can't start
+			const char* reason = QT_TR_NOOP("Could not launch minecraft!");
+			emit logLine(reason, MessageLevel::Fatal);
+			emitFailed(tr(reason));
+			return;
+		}
+		case LoggedProcess::Aborted:
+		case LoggedProcess::Crashed: {
+			m_parent->setPid(-1);
+			emitFailed(tr("Game crashed."));
+			return;
+		}
+		case LoggedProcess::Finished: {
+			m_parent->setPid(-1);
+			// if the exit code wasn't 0, report this as a crash
+			auto exitCode = m_process.exitCode();
+			if (exitCode != 0) {
+				emitFailed(tr("Game crashed."));
+				return;
+			}
+			// FIXME: make this work again
+			//  m_postlaunchprocess.processEnvironment().insert("INST_EXITCODE",
+			//  QString(exitCode)); run post-exit
+			emitSucceeded();
+			break;
+		}
+		case LoggedProcess::Running:
+			emit logLine(QString("Minecraft process ID: %1\n\n")
+							 .arg(m_process.processId()),
+						 MessageLevel::MeshMC);
+			m_parent->setPid(m_process.processId());
+			m_parent->instance()->setLastLaunch();
+			// send the launch script to MeshMC part
+			m_process.write(m_launchScript.toUtf8());
+
+			mayProceed = true;
+			emit readyForLaunch();
+			break;
+		default:
+			break;
+	}
+}
+
+void MeshMCPartLaunch::setWorkingDirectory(const QString& wd)
+{
+	m_process.setWorkingDirectory(wd);
+}
+
+void MeshMCPartLaunch::proceed()
+{
+	if (mayProceed) {
+		QString launchString("launch\n");
+		m_process.write(launchString.toUtf8());
+		mayProceed = false;
+	}
+}
+
+bool MeshMCPartLaunch::abort()
+{
+	if (mayProceed) {
+		mayProceed = false;
+		QString launchString("abort\n");
+		m_process.write(launchString.toUtf8());
+	} else {
+		auto state = m_process.state();
+		if (state == LoggedProcess::Running ||
+			state == LoggedProcess::Starting) {
+			m_process.kill();
+		}
+	}
+	return true;
+}
diff --git a/meshmc/launcher/minecraft/launch/MeshMCPartLaunch.h b/meshmc/launcher/minecraft/launch/MeshMCPartLaunch.h
new file mode 100644
index 0000000000..ff4285365f
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/MeshMCPartLaunch.h
@@ -0,0 +1,83 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <LoggedProcess.h>
+#include <minecraft/auth/AuthSession.h>
+
+#include "MinecraftServerTarget.h"
+
+class MeshMCPartLaunch : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit MeshMCPartLaunch(LaunchTask* parent);
+	virtual ~MeshMCPartLaunch() {};
+
+	virtual void executeTask();
+	virtual bool abort();
+	virtual void proceed();
+	virtual bool canAbort() const
+	{
+		return true;
+	}
+	void setWorkingDirectory(const QString& wd);
+	void setAuthSession(AuthSessionPtr session)
+	{
+		m_session = session;
+	}
+
+	void setServerToJoin(MinecraftServerTargetPtr serverToJoin)
+	{
+		m_serverToJoin = std::move(serverToJoin);
+	}
+
+  private slots:
+	void on_state(LoggedProcess::State state);
+
+  private:
+	LoggedProcess m_process;
+	QString m_command;
+	AuthSessionPtr m_session;
+	QString m_launchScript;
+	MinecraftServerTargetPtr m_serverToJoin;
+
+	bool mayProceed = false;
+};
diff --git a/meshmc/launcher/minecraft/launch/MinecraftServerTarget.cpp b/meshmc/launcher/minecraft/launch/MinecraftServerTarget.cpp
new file mode 100644
index 0000000000..a3443ce6a0
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/MinecraftServerTarget.cpp
@@ -0,0 +1,85 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "MinecraftServerTarget.h"
+
+#include <QStringList>
+
+// FIXME: the way this is written, it can't ever do any sort of validation and
+// can accept total junk
+MinecraftServerTarget MinecraftServerTarget::parse(const QString& fullAddress)
+{
+	QStringList split = fullAddress.split(":");
+
+	// The logic below replicates the exact logic minecraft uses for parsing
+	// server addresses. While the conversion is not lossless and eats errors,
+	// it ensures the same behavior within Minecraft and MeshMC when entering
+	// server addresses.
+	if (fullAddress.startsWith("[")) {
+		int bracket = fullAddress.indexOf("]");
+		if (bracket > 0) {
+			QString ipv6 = fullAddress.mid(1, bracket - 1);
+			QString port = fullAddress.mid(bracket + 1).trimmed();
+
+			if (port.startsWith(":") && !ipv6.isEmpty()) {
+				port = port.mid(1);
+				split = QStringList({ipv6, port});
+			} else {
+				split = QStringList({ipv6});
+			}
+		}
+	}
+
+	if (split.size() > 2) {
+		split = QStringList({fullAddress});
+	}
+
+	QString realAddress = split[0];
+
+	quint16 realPort = 25565;
+	if (split.size() > 1) {
+		bool ok;
+		realPort = split[1].toUInt(&ok);
+
+		if (!ok) {
+			realPort = 25565;
+		}
+	}
+
+	return MinecraftServerTarget{realAddress, realPort};
+}
diff --git a/meshmc/launcher/minecraft/launch/MinecraftServerTarget.h b/meshmc/launcher/minecraft/launch/MinecraftServerTarget.h
new file mode 100644
index 0000000000..ae453d637d
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/MinecraftServerTarget.h
@@ -0,0 +1,52 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <memory>
+
+#include <QString>
+
+struct MinecraftServerTarget {
+	QString address;
+	quint16 port;
+
+	static MinecraftServerTarget parse(const QString& fullAddress);
+};
+
+typedef std::shared_ptr<MinecraftServerTarget> MinecraftServerTargetPtr;
diff --git a/meshmc/launcher/minecraft/launch/ModMinecraftJar.cpp b/meshmc/launcher/minecraft/launch/ModMinecraftJar.cpp
new file mode 100644
index 0000000000..72da25ec64
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ModMinecraftJar.cpp
@@ -0,0 +1,103 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ModMinecraftJar.h"
+#include "launch/LaunchTask.h"
+#include "MMCZip.h"
+#include "minecraft/OpSys.h"
+#include "FileSystem.h"
+#include "minecraft/MinecraftInstance.h"
+#include "minecraft/PackProfile.h"
+
+void ModMinecraftJar::executeTask()
+{
+	auto m_inst =
+		std::dynamic_pointer_cast<MinecraftInstance>(m_parent->instance());
+
+	if (!m_inst->getJarMods().size()) {
+		emitSucceeded();
+		return;
+	}
+	// nuke obsolete stripped jar(s) if needed
+	if (!FS::ensureFolderPathExists(m_inst->binRoot())) {
+		emitFailed(tr("Couldn't create the bin folder for Minecraft.jar"));
+	}
+
+	auto finalJarPath =
+		QDir(m_inst->binRoot()).absoluteFilePath("minecraft.jar");
+	if (!removeJar()) {
+		emitFailed(tr("Couldn't remove stale jar file: %1").arg(finalJarPath));
+	}
+
+	// create temporary modded jar, if needed
+	auto components = m_inst->getPackProfile();
+	auto profile = components->getProfile();
+	auto jarMods = m_inst->getJarMods();
+	if (jarMods.size()) {
+		auto mainJar = profile->getMainJar();
+		QStringList jars, temp1, temp2, temp3, temp4;
+		mainJar->getApplicableFiles(currentSystem, jars, temp1, temp2, temp3,
+									m_inst->getLocalLibraryPath());
+		auto sourceJarPath = jars[0];
+		if (!MMCZip::createModdedJar(sourceJarPath, finalJarPath, jarMods)) {
+			emitFailed(tr("Failed to create the custom Minecraft jar file."));
+			return;
+		}
+	}
+	emitSucceeded();
+}
+
+void ModMinecraftJar::finalize()
+{
+	removeJar();
+}
+
+bool ModMinecraftJar::removeJar()
+{
+	auto m_inst =
+		std::dynamic_pointer_cast<MinecraftInstance>(m_parent->instance());
+	auto finalJarPath =
+		QDir(m_inst->binRoot()).absoluteFilePath("minecraft.jar");
+	QFile finalJar(finalJarPath);
+	if (finalJar.exists()) {
+		if (!finalJar.remove()) {
+			return false;
+		}
+	}
+	return true;
+}
diff --git a/meshmc/launcher/minecraft/launch/ModMinecraftJar.h b/meshmc/launcher/minecraft/launch/ModMinecraftJar.h
new file mode 100644
index 0000000000..9453dd233e
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ModMinecraftJar.h
@@ -0,0 +1,60 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <memory>
+
+class ModMinecraftJar : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit ModMinecraftJar(LaunchTask* parent) : LaunchStep(parent) {};
+	virtual ~ModMinecraftJar() {};
+
+	virtual void executeTask() override;
+	virtual bool canAbort() const override
+	{
+		return false;
+	}
+	void finalize() override;
+
+  private:
+	bool removeJar();
+};
diff --git a/meshmc/launcher/minecraft/launch/PrintInstanceInfo.cpp b/meshmc/launcher/minecraft/launch/PrintInstanceInfo.cpp
new file mode 100644
index 0000000000..b7fabeb606
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/PrintInstanceInfo.cpp
@@ -0,0 +1,166 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <fstream>
+#include <string>
+
+#include "PrintInstanceInfo.h"
+#include <launch/LaunchTask.h>
+
+#if defined(Q_OS_LINUX) || defined(Q_OS_FREEBSD)
+namespace
+{
+#if defined(Q_OS_LINUX)
+	void probeProcCpuinfo(QStringList& log)
+	{
+		std::ifstream cpuin("/proc/cpuinfo");
+		for (std::string line; std::getline(cpuin, line);) {
+			if (strncmp(line.c_str(), "model name", 10) == 0) {
+				log << QString::fromStdString(
+					line.substr(13, std::string::npos));
+				break;
+			}
+		}
+	}
+
+	void runLspci(QStringList& log)
+	{
+		// FIXME: fixed size buffers...
+		char buff[512];
+		int gpuline = -1;
+		int cline = 0;
+		FILE* lspci = popen("lspci -k", "r");
+
+		if (!lspci)
+			return;
+
+		while (fgets(buff, 512, lspci) != NULL) {
+			std::string str(buff);
+			if (str.length() < 9)
+				continue;
+			if (str.substr(8, 3) == "VGA") {
+				gpuline = cline;
+				log << QString::fromStdString(
+					str.substr(35, std::string::npos));
+			}
+			if (gpuline > -1 && gpuline != cline) {
+				if (cline - gpuline < 3) {
+					log << QString::fromStdString(
+						str.substr(1, std::string::npos));
+				}
+			}
+			cline++;
+		}
+		pclose(lspci);
+	}
+#elif defined(Q_OS_FREEBSD)
+	void runSysctlHwModel(QStringList& log)
+	{
+		char buff[512];
+		FILE* hwmodel = popen("sysctl hw.model", "r");
+		while (fgets(buff, 512, hwmodel) != NULL) {
+			log << QString::fromUtf8(buff);
+			break;
+		}
+		pclose(hwmodel);
+	}
+
+	void runPciconf(QStringList& log)
+	{
+		char buff[512];
+		std::string strcard;
+		FILE* pciconf = popen("pciconf -lv -a vgapci0", "r");
+		while (fgets(buff, 512, pciconf) != NULL) {
+			if (strncmp(buff, "    vendor", 10) == 0) {
+				std::string str(buff);
+				strcard.append(str.substr(str.find_first_of("'") + 1,
+										  str.find_last_not_of("'") -
+											  (str.find_first_of("'") + 2)));
+				strcard.append(" ");
+			} else if (strncmp(buff, "    device", 10) == 0) {
+				std::string str2(buff);
+				strcard.append(str2.substr(str2.find_first_of("'") + 1,
+										   str2.find_last_not_of("'") -
+											   (str2.find_first_of("'") + 2)));
+			}
+			log << QString::fromStdString(strcard);
+			break;
+		}
+		pclose(pciconf);
+	}
+#endif
+	void runGlxinfo(QStringList& log)
+	{
+		// FIXME: fixed size buffers...
+		char buff[512];
+		FILE* glxinfo = popen("glxinfo", "r");
+		if (!glxinfo)
+			return;
+
+		while (fgets(buff, 512, glxinfo) != NULL) {
+			if (strncmp(buff, "OpenGL version string:", 22) == 0) {
+				log << QString::fromUtf8(buff);
+				break;
+			}
+		}
+		pclose(glxinfo);
+	}
+
+} // namespace
+#endif
+
+void PrintInstanceInfo::executeTask()
+{
+	auto instance = m_parent->instance();
+	QStringList log;
+
+#if defined(Q_OS_LINUX)
+	::probeProcCpuinfo(log);
+	::runLspci(log);
+	::runGlxinfo(log);
+#elif defined(Q_OS_FREEBSD)
+	::runSysctlHwModel(log);
+	::runPciconf(log);
+	::runGlxinfo(log);
+#endif
+
+	logLines(log, MessageLevel::MeshMC);
+	logLines(instance->verboseDescription(m_session, m_serverToJoin),
+			 MessageLevel::MeshMC);
+	emitSucceeded();
+}
diff --git a/meshmc/launcher/minecraft/launch/PrintInstanceInfo.h b/meshmc/launcher/minecraft/launch/PrintInstanceInfo.h
new file mode 100644
index 0000000000..572c5c84c7
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/PrintInstanceInfo.h
@@ -0,0 +1,66 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <memory>
+#include "minecraft/auth/AuthSession.h"
+#include "minecraft/launch/MinecraftServerTarget.h"
+
+// FIXME: temporary wrapper for existing task.
+class PrintInstanceInfo : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit PrintInstanceInfo(LaunchTask* parent, AuthSessionPtr session,
+							   MinecraftServerTargetPtr serverToJoin)
+		: LaunchStep(parent), m_session(session),
+		  m_serverToJoin(serverToJoin) {};
+	virtual ~PrintInstanceInfo() {};
+
+	virtual void executeTask();
+	virtual bool canAbort() const
+	{
+		return false;
+	}
+
+  private:
+	AuthSessionPtr m_session;
+	MinecraftServerTargetPtr m_serverToJoin;
+};
diff --git a/meshmc/launcher/minecraft/launch/ReconstructAssets.cpp b/meshmc/launcher/minecraft/launch/ReconstructAssets.cpp
new file mode 100644
index 0000000000..95c9bedda3
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ReconstructAssets.cpp
@@ -0,0 +1,61 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ReconstructAssets.h"
+#include "minecraft/MinecraftInstance.h"
+#include "minecraft/PackProfile.h"
+#include "minecraft/AssetsUtils.h"
+#include "launch/LaunchTask.h"
+
+void ReconstructAssets::executeTask()
+{
+	auto instance = m_parent->instance();
+	std::shared_ptr<MinecraftInstance> minecraftInstance =
+		std::dynamic_pointer_cast<MinecraftInstance>(instance);
+	auto components = minecraftInstance->getPackProfile();
+	auto profile = components->getProfile();
+	auto assets = profile->getMinecraftAssets();
+
+	if (!AssetsUtils::reconstructAssets(assets->id,
+										minecraftInstance->resourcesDir())) {
+		emit logLine("Failed to reconstruct Minecraft assets.",
+					 MessageLevel::Error);
+	}
+
+	emitSucceeded();
+}
diff --git a/meshmc/launcher/minecraft/launch/ReconstructAssets.h b/meshmc/launcher/minecraft/launch/ReconstructAssets.h
new file mode 100644
index 0000000000..1f080485c0
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ReconstructAssets.h
@@ -0,0 +1,56 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <memory>
+
+class ReconstructAssets : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit ReconstructAssets(LaunchTask* parent) : LaunchStep(parent) {};
+	virtual ~ReconstructAssets() {};
+
+	void executeTask() override;
+	bool canAbort() const override
+	{
+		return false;
+	}
+};
diff --git a/meshmc/launcher/minecraft/launch/ScanModFolders.cpp b/meshmc/launcher/minecraft/launch/ScanModFolders.cpp
new file mode 100644
index 0000000000..e9829718c7
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ScanModFolders.cpp
@@ -0,0 +1,85 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ScanModFolders.h"
+#include "launch/LaunchTask.h"
+#include "MMCZip.h"
+#include "minecraft/OpSys.h"
+#include "FileSystem.h"
+#include "minecraft/MinecraftInstance.h"
+#include "minecraft/mod/ModFolderModel.h"
+
+void ScanModFolders::executeTask()
+{
+	auto m_inst =
+		std::dynamic_pointer_cast<MinecraftInstance>(m_parent->instance());
+
+	auto loaders = m_inst->loaderModList();
+	connect(loaders.get(), &ModFolderModel::updateFinished, this,
+			&ScanModFolders::modsDone);
+	if (!loaders->update()) {
+		m_modsDone = true;
+	}
+
+	auto cores = m_inst->coreModList();
+	connect(cores.get(), &ModFolderModel::updateFinished, this,
+			&ScanModFolders::coreModsDone);
+	if (!cores->update()) {
+		m_coreModsDone = true;
+	}
+	checkDone();
+}
+
+void ScanModFolders::modsDone()
+{
+	m_modsDone = true;
+	checkDone();
+}
+
+void ScanModFolders::coreModsDone()
+{
+	m_coreModsDone = true;
+	checkDone();
+}
+
+void ScanModFolders::checkDone()
+{
+	if (m_modsDone && m_coreModsDone) {
+		emitSucceeded();
+	}
+}
diff --git a/meshmc/launcher/minecraft/launch/ScanModFolders.h b/meshmc/launcher/minecraft/launch/ScanModFolders.h
new file mode 100644
index 0000000000..e572022c90
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/ScanModFolders.h
@@ -0,0 +1,66 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *  This file incorporates work covered by the following copyright and
+ *  permission notice:
+ *
+ * Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <memory>
+
+class ScanModFolders : public LaunchStep
+{
+	Q_OBJECT
+  public:
+	explicit ScanModFolders(LaunchTask* parent) : LaunchStep(parent) {};
+	virtual ~ScanModFolders() {};
+
+	virtual void executeTask() override;
+	virtual bool canAbort() const override
+	{
+		return false;
+	}
+  private slots:
+	void coreModsDone();
+	void modsDone();
+
+  private:
+	void checkDone();
+
+  private: // DATA
+	bool m_modsDone = false;
+	bool m_coreModsDone = false;
+};
diff --git a/meshmc/launcher/minecraft/launch/VerifyJavaInstall.cpp b/meshmc/launcher/minecraft/launch/VerifyJavaInstall.cpp
new file mode 100644
index 0000000000..0f58b5efa4
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/VerifyJavaInstall.cpp
@@ -0,0 +1,374 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "VerifyJavaInstall.h"
+
+#include <QDir>
+#include <QDirIterator>
+#include <QFileInfo>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QProcess>
+#include <QRegularExpression>
+
+#include <launch/LaunchTask.h>
+#include <minecraft/MinecraftInstance.h>
+#include <minecraft/PackProfile.h>
+#include <minecraft/VersionFilterData.h>
+
+#include "Application.h"
+#include "FileSystem.h"
+#include "Json.h"
+#include "java/JavaUtils.h"
+
+#ifndef MeshMC_DISABLE_JAVA_DOWNLOADER
+#include "BuildConfig.h"
+#include "net/Download.h"
+#endif
+
+#ifdef major
+#undef major
+#endif
+#ifdef minor
+#undef minor
+#endif
+
+namespace
+{
+	std::optional<JavaVersion> probeJavaVersion(const QString& javaPath)
+	{
+		const auto checkerJar =
+			FS::PathCombine(APPLICATION->getJarsPath(), "JavaCheck.jar");
+		if (!QFileInfo::exists(checkerJar)) {
+			return std::nullopt;
+		}
+
+		QProcess process;
+		process.setProgram(javaPath);
+		process.setArguments({"-jar", checkerJar});
+		process.setProcessEnvironment(CleanEnviroment());
+		process.setProcessChannelMode(QProcess::SeparateChannels);
+		process.start();
+
+		if (!process.waitForFinished(15000) ||
+			process.exitStatus() != QProcess::NormalExit ||
+			process.exitCode() != 0) {
+			return std::nullopt;
+		}
+
+		const auto stdoutData =
+			QString::fromLocal8Bit(process.readAllStandardOutput());
+		const auto lines = stdoutData.split('\n', Qt::SkipEmptyParts);
+		for (const auto& rawLine : lines) {
+			const auto line = rawLine.trimmed();
+			if (!line.startsWith("java.version=")) {
+				continue;
+			}
+			return JavaVersion(line.mid(QString("java.version=").size()));
+		}
+
+		return std::nullopt;
+	}
+} // namespace
+
+int VerifyJavaInstall::determineRequiredJavaMajor() const
+{
+	auto m_inst =
+		std::dynamic_pointer_cast<MinecraftInstance>(m_parent->instance());
+	auto minecraftComponent =
+		m_inst->getPackProfile()->getComponent("net.minecraft");
+
+	if (minecraftComponent->getReleaseDateTime() >=
+		g_VersionFilterData.java25BeginsDate)
+		return 25;
+	if (minecraftComponent->getReleaseDateTime() >=
+		g_VersionFilterData.java21BeginsDate)
+		return 21;
+	if (minecraftComponent->getReleaseDateTime() >=
+		g_VersionFilterData.java17BeginsDate)
+		return 17;
+	if (minecraftComponent->getReleaseDateTime() >=
+		g_VersionFilterData.java16BeginsDate)
+		return 16;
+	if (minecraftComponent->getReleaseDateTime() >=
+		g_VersionFilterData.java8BeginsDate)
+		return 8;
+	return 0;
+}
+
+QString VerifyJavaInstall::javaInstallDir() const
+{
+	return JavaUtils::managedJavaRoot();
+}
+
+QString VerifyJavaInstall::findInstalledJava(int requiredMajor) const
+{
+	JavaUtils javaUtils;
+	QList<QString> systemJavas = javaUtils.FindJavaPaths();
+	QSet<QString> seenPaths;
+	for (const QString& javaPath : systemJavas) {
+		QString resolved = FS::ResolveExecutable(javaPath);
+		if (resolved.isEmpty() || seenPaths.contains(resolved))
+			continue;
+
+		seenPaths.insert(resolved);
+		const auto version = probeJavaVersion(resolved);
+		if (version.has_value() && version->major() >= requiredMajor) {
+			return resolved;
+		}
+	}
+
+	return {};
+}
+
+void VerifyJavaInstall::executeTask()
+{
+	auto m_inst =
+		std::dynamic_pointer_cast<MinecraftInstance>(m_parent->instance());
+
+	auto javaVersion = m_inst->getJavaVersion();
+	int requiredMajor = determineRequiredJavaMajor();
+
+	// No Java requirement or already met
+	if (requiredMajor == 0 || javaVersion.major() >= requiredMajor) {
+		emitSucceeded();
+		return;
+	}
+
+	// Java version insufficient — try to find an already-downloaded one
+	emit logLine(
+		tr("Current Java version %1 does not meet the requirement of Java %2.")
+			.arg(javaVersion.toString())
+			.arg(requiredMajor),
+		MessageLevel::Warning);
+
+	QString existingJava = findInstalledJava(requiredMajor);
+	if (!existingJava.isEmpty()) {
+		emit logLine(tr("Found installed Java %1 at: %2")
+						 .arg(requiredMajor)
+						 .arg(existingJava),
+					 MessageLevel::MeshMC);
+#ifndef MeshMC_DISABLE_JAVA_DOWNLOADER
+		setJavaPathAndSucceed(existingJava);
+#else
+		m_inst->settings()->set("OverrideJavaLocation", true);
+		m_inst->settings()->set("JavaPath", existingJava);
+		emit logLine(tr("Java path set to: %1").arg(existingJava),
+					 MessageLevel::MeshMC);
+		emitSucceeded();
+#endif
+		return;
+	}
+
+#ifndef MeshMC_DISABLE_JAVA_DOWNLOADER
+	// Not found — auto-download
+	emit logLine(
+		tr("No installed Java %1 found. Downloading...").arg(requiredMajor),
+		MessageLevel::MeshMC);
+	autoDownloadJava(requiredMajor);
+#else
+	emitFailed(
+		tr("Java %1 is required but not installed. Please install it manually.")
+			.arg(requiredMajor));
+#endif
+}
+
+#ifndef MeshMC_DISABLE_JAVA_DOWNLOADER
+void VerifyJavaInstall::autoDownloadJava(int requiredMajor)
+{
+	// Fetch version list from net.minecraft.java (Mojang)
+	fetchVersionList(requiredMajor);
+}
+
+void VerifyJavaInstall::fetchVersionList(int requiredMajor)
+{
+	m_fetchData.clear();
+	QString uid = "net.minecraft.java";
+	QString url = QString("%1%2/index.json").arg(BuildConfig.META_URL, uid);
+
+	m_fetchJob = new NetJob(tr("Fetch Java versions"), APPLICATION->network());
+	auto dl = Net::Download::makeByteArray(QUrl(url), &m_fetchData);
+	m_fetchJob->addNetAction(dl);
+
+	connect(
+		m_fetchJob.get(), &NetJob::succeeded, this,
+		[this, uid, requiredMajor]() {
+			m_fetchJob.reset();
+
+			QJsonDocument doc;
+			try {
+				doc = Json::requireDocument(m_fetchData);
+			} catch (const Exception& e) {
+				emitFailed(
+					tr("Failed to parse Java version list from meta server: %1")
+						.arg(e.cause()));
+				return;
+			}
+			if (!doc.isObject()) {
+				emitFailed(
+					tr("Failed to parse Java version list from meta server."));
+				return;
+			}
+
+			auto versions = JavaDownload::parseVersionIndex(doc.object(), uid);
+
+			// Find the matching version (e.g., "java25" for requiredMajor=25)
+			QString targetVersionId = QString("java%1").arg(requiredMajor);
+			bool found = false;
+			for (const auto& ver : versions) {
+				if (ver.versionId == targetVersionId) {
+					found = true;
+					fetchRuntimes(ver.versionId, requiredMajor);
+					return;
+				}
+			}
+
+			if (!found) {
+				emitFailed(tr("Java %1 is not available for download from "
+							  "Mojang. Please install it manually.")
+							   .arg(requiredMajor));
+			}
+		});
+
+	connect(m_fetchJob.get(), &NetJob::failed, this,
+			[this, requiredMajor](QString reason) {
+				emitFailed(tr("Failed to fetch Java version list: %1. Please "
+							  "install Java %2 manually.")
+							   .arg(reason)
+							   .arg(requiredMajor));
+				m_fetchJob.reset();
+			});
+
+	m_fetchJob->start();
+}
+
+void VerifyJavaInstall::fetchRuntimes(const QString& versionId,
+									  int requiredMajor)
+{
+	m_fetchData.clear();
+	QString uid = "net.minecraft.java";
+	QString url =
+		QString("%1%2/%3.json").arg(BuildConfig.META_URL, uid, versionId);
+
+	m_fetchJob =
+		new NetJob(tr("Fetch Java runtime details"), APPLICATION->network());
+	auto dl = Net::Download::makeByteArray(QUrl(url), &m_fetchData);
+	m_fetchJob->addNetAction(dl);
+
+	connect(m_fetchJob.get(), &NetJob::succeeded, this,
+			[this, requiredMajor]() {
+				auto fetchJob = std::move(m_fetchJob);
+
+				QJsonDocument doc;
+				try {
+					doc = Json::requireDocument(m_fetchData);
+				} catch (const Exception& e) {
+					emitFailed(tr("Failed to parse Java runtime details: %1")
+								   .arg(e.cause()));
+					return;
+				}
+				if (!doc.isObject()) {
+					emitFailed(tr("Failed to parse Java runtime details."));
+					return;
+				}
+
+				auto allRuntimes = JavaDownload::parseRuntimes(doc.object());
+				QString myOS = JavaDownload::currentRuntimeOS();
+
+				// Filter for current platform
+				for (const auto& rt : allRuntimes) {
+					if (rt.runtimeOS == myOS) {
+						emit logLine(tr("Downloading %1 (%2)...")
+										 .arg(rt.name, rt.version.toString()),
+									 MessageLevel::MeshMC);
+						startDownload(rt, requiredMajor);
+						return;
+					}
+				}
+
+				emitFailed(tr("No Java %1 download available for your platform "
+							  "(%2). Please install it manually.")
+							   .arg(requiredMajor)
+							   .arg(myOS));
+			});
+
+	connect(m_fetchJob.get(), &NetJob::failed, this, [this](QString reason) {
+		emitFailed(tr("Failed to fetch Java runtime details: %1").arg(reason));
+		m_fetchJob.reset();
+	});
+
+	m_fetchJob->start();
+}
+
+void VerifyJavaInstall::startDownload(const JavaDownload::RuntimeEntry& runtime,
+									  int requiredMajor)
+{
+	QString dirName =
+		QString("%1-%2").arg(runtime.name, runtime.version.toString());
+	QString targetDir =
+		FS::PathCombine(javaInstallDir(), runtime.vendor, dirName);
+
+	m_downloadTask =
+		std::make_unique<JavaDownloadTask>(runtime, targetDir, this);
+
+	connect(m_downloadTask.get(), &Task::succeeded, this, [this]() {
+		QString javaPath = m_downloadTask->installedJavaPath();
+
+		if (javaPath.isEmpty()) {
+			emitFailed(
+				tr("Java was downloaded but the binary could not be found."));
+			return;
+		}
+
+		emit logLine(tr("Java downloaded and installed at: %1").arg(javaPath),
+					 MessageLevel::MeshMC);
+		setJavaPathAndSucceed(javaPath);
+	});
+
+	connect(m_downloadTask.get(), &Task::failed, this,
+			[this, requiredMajor](const QString& reason) {
+				emitFailed(tr("Failed to download Java %1: %2")
+							   .arg(requiredMajor)
+							   .arg(reason));
+				m_downloadTask.reset();
+			});
+
+	connect(m_downloadTask.get(), &Task::status, this,
+			[this](const QString& status) {
+				emit logLine(status, MessageLevel::MeshMC);
+			});
+
+	m_downloadTask->start();
+}
+
+void VerifyJavaInstall::setJavaPathAndSucceed(const QString& javaPath)
+{
+	auto m_inst =
+		std::dynamic_pointer_cast<MinecraftInstance>(m_parent->instance());
+	// Set Java path override on the instance only, not globally
+	m_inst->settings()->set("OverrideJavaLocation", true);
+	m_inst->settings()->set("JavaPath", javaPath);
+	emit logLine(tr("Java path set to: %1").arg(javaPath),
+				 MessageLevel::MeshMC);
+	emitSucceeded();
+}
+#endif
diff --git a/meshmc/launcher/minecraft/launch/VerifyJavaInstall.h b/meshmc/launcher/minecraft/launch/VerifyJavaInstall.h
new file mode 100644
index 0000000000..f54717e403
--- /dev/null
+++ b/meshmc/launcher/minecraft/launch/VerifyJavaInstall.h
@@ -0,0 +1,61 @@
+/* SPDX-FileCopyrightText: 2026 Project Tick
+ * SPDX-FileContributor: Project Tick
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   MeshMC - A Custom Launcher for Minecraft
+ *   Copyright (C) 2026 Project Tick
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#ifndef MeshMC_DISABLE_JAVA_DOWNLOADER
+#include "java/download/JavaRuntime.h"
+#include "java/download/JavaDownloadTask.h"
+#endif
+#include "net/NetJob.h"
+
+class VerifyJavaInstall : public LaunchStep
+{
+	Q_OBJECT
+
+  public:
+	explicit VerifyJavaInstall(LaunchTask* parent) : LaunchStep(parent) {};
+	~VerifyJavaInstall() override = default;
+
+	void executeTask() override;
+	bool canAbort() const override
+	{
+		return false;
+	}
+
+  private:
+	int determineRequiredJavaMajor() const;
+	QString findInstalledJava(int requiredMajor) const;
+	QString javaInstallDir() const;
+#ifndef MeshMC_DISABLE_JAVA_DOWNLOADER
+	void autoDownloadJava(int requiredMajor);
+	void fetchVersionList(int requiredMajor);
+	void fetchRuntimes(const QString& versionId, int requiredMajor);
+	void startDownload(const JavaDownload::RuntimeEntry& runtime,
+					   int requiredMajor);
+	void setJavaPathAndSucceed(const QString& javaPath);
+
+	NetJob::Ptr m_fetchJob;
+	QByteArray m_fetchData;
+	std::unique_ptr<JavaDownloadTask> m_downloadTask;
+#endif
+};