Add native Root Builder and OMOD Installer plugins

- libs/rootbuilder_native/: Native C++ port of rootbuilder.py (IPluginTool)
  - Root/ dir scanning, copy (reflink/CoW) and symlink modes
  - JSON manifest tracking, backup/restore, auto-deploy hooks
  - Legacy migration and third-party conflict detection
- libs/installer_omod_native/: Native C++ port of installer_omod.py
  - Handles .omod archives (Oblivion Mod Manager format)
  - Binary config parsing, .NET string format, CRC file parsing
  - zlib raw deflate and LZMA decompression
  - Repackages to zip for MO2's installation manager
- Added both to build-inner.sh plugin packaging

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

4 files changed, 774 insertions, 0 deletions

diff --git a/libs/rootbuilder_native/CMakeLists.txt b/libs/rootbuilder_native/CMakeLists.txt
new file mode 100644
index 0000000..583c0ac
--- /dev/null
+++ b/libs/rootbuilder_native/CMakeLists.txt
@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.16)
+project(rootbuilder_native)
+add_subdirectory(src)
diff --git a/libs/rootbuilder_native/src/CMakeLists.txt b/libs/rootbuilder_native/src/CMakeLists.txt
new file mode 100644
index 0000000..438c068
--- /dev/null
+++ b/libs/rootbuilder_native/src/CMakeLists.txt
@@ -0,0 +1,18 @@
+cmake_minimum_required(VERSION 3.16)
+
+find_package(Qt6 REQUIRED COMPONENTS Widgets)
+qt_standard_project_setup()
+
+file(GLOB SOURCES *.cpp *.h)
+
+add_library(rootbuilder_native SHARED ${SOURCES})
+
+set_target_properties(rootbuilder_native PROPERTIES
+    AUTOMOC ON
+    CXX_STANDARD 23
+    CXX_STANDARD_REQUIRED ON
+    PREFIX "lib"
+)
+
+target_link_libraries(rootbuilder_native PRIVATE mo2::uibase Qt6::Widgets)
+install(TARGETS rootbuilder_native LIBRARY DESTINATION bin/plugins)
diff --git a/libs/rootbuilder_native/src/rootbuilder.cpp b/libs/rootbuilder_native/src/rootbuilder.cpp
new file mode 100644
index 0000000..6ee2e1c
--- /dev/null
+++ b/libs/rootbuilder_native/src/rootbuilder.cpp
@@ -0,0 +1,674 @@
+#include "rootbuilder.h"
+
+#include <uibase/imodinterface.h>
+#include <uibase/imodlist.h>
+#include <uibase/iplugingame.h>
+#include <uibase/versioninfo.h>
+
+#include <QCoreApplication>
+#include <QCheckBox>
+#include <QComboBox>
+#include <QDialog>
+#include <QDir>
+#include <QDirIterator>
+#include <QFile>
+#include <QFileInfo>
+#include <QHBoxLayout>
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QLabel>
+#include <QProcess>
+#include <QPushButton>
+#include <QVBoxLayout>
+
+#include <algorithm>
+#include <set>
+
+// Storage constants
+static const QString STORAGE_SUBDIR   = QStringLiteral("rootbuilder");
+static const QString MANIFEST_NAME    = QStringLiteral("manifest.json");
+static const QString SETTINGS_NAME    = QStringLiteral("settings.json");
+static const QString BACKUP_SUBDIR    = QStringLiteral("backup");
+static const QString LEGACY_MANIFEST  = QStringLiteral(".rootbuilder_manifest.json");
+static const QString LEGACY_BACKUP    = QStringLiteral(".rootbuilder_backup");
+
+// ============================================================================
+// Construction / IPlugin
+// ============================================================================
+
+RootBuilderNative::RootBuilderNative() = default;
+
+bool RootBuilderNative::init(MOBase::IOrganizer* organizer)
+{
+    m_organizer = organizer;
+    migrateLegacy();
+    checkThirdPartyRootBuilder();
+
+    organizer->onAboutToRun([this](const QString& exe) {
+        return onAboutToRun(exe);
+    });
+    organizer->onFinishedRun([this](const QString& exe, unsigned int code) {
+        onFinishedRun(exe, code);
+    });
+
+    return true;
+}
+
+QString RootBuilderNative::name() const
+{
+    return QStringLiteral("Root Builder (Native)");
+}
+
+QString RootBuilderNative::localizedName() const
+{
+    return QStringLiteral("Root Builder (Native)");
+}
+
+QString RootBuilderNative::author() const
+{
+    return QStringLiteral("Fluorine Manager");
+}
+
+QString RootBuilderNative::description() const
+{
+    return QStringLiteral(
+        "Deploys mod files from Root/ subdirectories to the game's root directory. "
+        "Supports copy and symlink modes with auto-deploy on launch.");
+}
+
+MOBase::VersionInfo RootBuilderNative::version() const
+{
+    return MOBase::VersionInfo(1, 0, 0);
+}
+
+QList<MOBase::PluginSetting> RootBuilderNative::settings() const
+{
+    return {};
+}
+
+bool RootBuilderNative::enabledByDefault() const
+{
+    return true;
+}
+
+// ============================================================================
+// IPluginTool
+// ============================================================================
+
+QString RootBuilderNative::displayName() const
+{
+    return QStringLiteral("Root Builder");
+}
+
+QString RootBuilderNative::tooltip() const
+{
+    return QStringLiteral("Deploy mod Root/ files to the game directory");
+}
+
+QIcon RootBuilderNative::icon() const
+{
+    return QIcon();
+}
+
+void RootBuilderNative::display() const
+{
+    QJsonObject settings = loadSettings();
+
+    // We need non-const this for build/clear — display() is const in the
+    // interface, but build/clear mutate the filesystem (not object state).
+    auto* self = const_cast<RootBuilderNative*>(this);
+
+    auto* dialog = new QDialog(parentWidget());
+    dialog->setAttribute(Qt::WA_DeleteOnClose);
+    dialog->setWindowTitle(QStringLiteral("Root Builder"));
+    dialog->resize(350, 220);
+
+    auto* layout = new QVBoxLayout(dialog);
+
+    auto* desc = new QLabel(
+        QStringLiteral("Deploys files from mod Root/ folders to the game directory."));
+    desc->setWordWrap(true);
+    layout->addWidget(desc);
+
+    // Enable checkbox
+    auto* enableCheck = new QCheckBox(QStringLiteral("Auto-deploy on game launch"));
+    enableCheck->setChecked(settings.value(QStringLiteral("enabled")).toBool(false));
+    layout->addWidget(enableCheck);
+
+    // Mode selector
+    auto* modeLayout = new QHBoxLayout();
+    modeLayout->addWidget(new QLabel(QStringLiteral("Deploy mode:")));
+    auto* modeCombo = new QComboBox();
+    modeCombo->addItems({QStringLiteral("copy"), QStringLiteral("link")});
+    modeCombo->setCurrentText(
+        settings.value(QStringLiteral("mode")).toString(QStringLiteral("copy")));
+    modeLayout->addWidget(modeCombo);
+    layout->addLayout(modeLayout);
+
+    // Manual build/clear buttons
+    auto* btnLayout = new QHBoxLayout();
+    auto* buildBtn  = new QPushButton(QStringLiteral("Build Now"));
+    auto* clearBtn  = new QPushButton(QStringLiteral("Clear Now"));
+    btnLayout->addWidget(buildBtn);
+    btnLayout->addWidget(clearBtn);
+    layout->addLayout(btnLayout);
+
+    // Status label
+    auto* statusLabel = new QLabel();
+    layout->addWidget(statusLabel);
+
+    // Close button
+    auto* closeBtn = new QPushButton(QStringLiteral("Close"));
+    layout->addWidget(closeBtn);
+
+    // Save helper — captures enableCheck and modeCombo
+    auto doSave = [this, enableCheck, modeCombo]() {
+        QJsonObject s;
+        s[QStringLiteral("enabled")] = enableCheck->isChecked();
+        s[QStringLiteral("mode")]    = modeCombo->currentText();
+        saveSettings(s);
+    };
+
+    QObject::connect(enableCheck, &QCheckBox::stateChanged, dialog, [doSave](int) {
+        doSave();
+    });
+    QObject::connect(modeCombo, &QComboBox::currentTextChanged, dialog,
+                     [doSave](const QString&) { doSave(); });
+
+    QObject::connect(buildBtn, &QPushButton::clicked, dialog,
+                     [self, statusLabel]() {
+                         int count = self->build();
+                         statusLabel->setText(
+                             QStringLiteral("Deployed %1 file(s).").arg(count));
+                     });
+
+    QObject::connect(clearBtn, &QPushButton::clicked, dialog,
+                     [self, statusLabel]() {
+                         int count = self->clear();
+                         statusLabel->setText(
+                             QStringLiteral("Cleared %1 file(s).").arg(count));
+                     });
+
+    QObject::connect(closeBtn, &QPushButton::clicked, dialog, &QDialog::accept);
+
+    dialog->exec();
+}
+
+// ============================================================================
+// Hooks
+// ============================================================================
+
+bool RootBuilderNative::onAboutToRun(const QString& /*executable*/)
+{
+    if (isAutoEnabled())
+        build();
+    return true;
+}
+
+void RootBuilderNative::onFinishedRun(const QString& /*executable*/,
+                                      unsigned int /*exitCode*/)
+{
+    if (isAutoEnabled())
+        clear();
+}
+
+// ============================================================================
+// Storage paths
+// ============================================================================
+
+QString RootBuilderNative::storageDir() const
+{
+    QString d = m_organizer->basePath() + QStringLiteral("/") + STORAGE_SUBDIR;
+    QDir().mkpath(d);
+    return d;
+}
+
+QString RootBuilderNative::backupDir() const
+{
+    return storageDir() + QStringLiteral("/") + BACKUP_SUBDIR;
+}
+
+QString RootBuilderNative::manifestPath() const
+{
+    return storageDir() + QStringLiteral("/") + MANIFEST_NAME;
+}
+
+QString RootBuilderNative::settingsPath() const
+{
+    return storageDir() + QStringLiteral("/") + SETTINGS_NAME;
+}
+
+// ============================================================================
+// Settings (own JSON)
+// ============================================================================
+
+QJsonObject RootBuilderNative::loadSettings() const
+{
+    QFile f(settingsPath());
+    if (!f.open(QIODevice::ReadOnly))
+        return QJsonObject{
+            {QStringLiteral("enabled"), false},
+            {QStringLiteral("mode"), QStringLiteral("copy")}};
+
+    QJsonParseError err;
+    auto doc = QJsonDocument::fromJson(f.readAll(), &err);
+    if (err.error != QJsonParseError::NoError || !doc.isObject())
+        return QJsonObject{
+            {QStringLiteral("enabled"), false},
+            {QStringLiteral("mode"), QStringLiteral("copy")}};
+
+    return doc.object();
+}
+
+void RootBuilderNative::saveSettings(const QJsonObject& settings) const
+{
+    QDir().mkpath(storageDir());
+    QFile f(settingsPath());
+    if (f.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
+        f.write(QJsonDocument(settings).toJson(QJsonDocument::Indented));
+    }
+}
+
+bool RootBuilderNative::isAutoEnabled() const
+{
+    return loadSettings().value(QStringLiteral("enabled")).toBool(false);
+}
+
+// ============================================================================
+// Manifest
+// ============================================================================
+
+QJsonObject RootBuilderNative::loadManifest() const
+{
+    QFile f(manifestPath());
+    if (!f.open(QIODevice::ReadOnly))
+        return QJsonObject();
+
+    QJsonParseError err;
+    auto doc = QJsonDocument::fromJson(f.readAll(), &err);
+    if (err.error != QJsonParseError::NoError || !doc.isObject())
+        return QJsonObject();
+
+    return doc.object();
+}
+
+void RootBuilderNative::saveManifest(const QJsonObject& manifest) const
+{
+    QDir().mkpath(storageDir());
+    QFile f(manifestPath());
+    if (f.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
+        f.write(QJsonDocument(manifest).toJson(QJsonDocument::Indented));
+    }
+}
+
+void RootBuilderNative::removeManifest() const
+{
+    QFile::remove(manifestPath());
+}
+
+// ============================================================================
+// Legacy migration
+// ============================================================================
+
+void RootBuilderNative::migrateLegacy() const
+{
+    auto* game = m_organizer->managedGame();
+    if (!game)
+        return;
+
+    QString gameDir = game->gameDirectory().absolutePath();
+    QString storage = storageDir();
+
+    // Migrate manifest
+    QString oldManifest = gameDir + QStringLiteral("/") + LEGACY_MANIFEST;
+    if (QFileInfo::exists(oldManifest)) {
+        QString newPath = storage + QStringLiteral("/") + MANIFEST_NAME;
+        if (!QFileInfo::exists(newPath))
+            QFile::copy(oldManifest, newPath);
+        forceRemove(oldManifest);
+    }
+
+    // Migrate backup directory
+    QString oldBackup = gameDir + QStringLiteral("/") + LEGACY_BACKUP;
+    QFileInfo oldBackupInfo(oldBackup);
+    if (oldBackupInfo.isDir()) {
+        QString newBackup = storage + QStringLiteral("/") + BACKUP_SUBDIR;
+        if (!QFileInfo(newBackup).isDir()) {
+            // Copy tree
+            QDir().mkpath(newBackup);
+            QDirIterator it(oldBackup, QDir::Files, QDirIterator::Subdirectories);
+            while (it.hasNext()) {
+                it.next();
+                QString rel = QDir(oldBackup).relativeFilePath(it.filePath());
+                QString dst = newBackup + QStringLiteral("/") + rel;
+                QDir().mkpath(QFileInfo(dst).absolutePath());
+                QFile::copy(it.filePath(), dst);
+            }
+        }
+        // Remove old backup tree
+        QDir(oldBackup).removeRecursively();
+    }
+}
+
+// ============================================================================
+// Third-party conflict detection
+// ============================================================================
+
+void RootBuilderNative::checkThirdPartyRootBuilder() const
+{
+    // Locate the plugins directory (where .py/.so plugins live, next to the binary)
+    QString pluginsDir = QCoreApplication::applicationDirPath() + QStringLiteral("/plugins");
+    if (!QDir(pluginsDir).exists())
+        return;
+
+    QString disabledDir =
+        QCoreApplication::applicationDirPath() + QStringLiteral("/DisabledPlugins");
+
+    QDir dir(pluginsDir);
+    const auto entries = dir.entryInfoList(QDir::Files | QDir::Dirs | QDir::NoDotAndDotDot);
+
+    for (const auto& entry : entries) {
+        bool conflict = false;
+        QString entryName = entry.fileName();
+
+        if (entry.isDir() && entryName.compare(QStringLiteral("rootbuilder"),
+                                                Qt::CaseInsensitive) == 0) {
+            conflict = true;
+        } else if (entry.isFile() &&
+                   entryName.toLower().startsWith(QStringLiteral("rootbuilder")) &&
+                   entryName.toLower().endsWith(QStringLiteral(".py"))) {
+            // Don't move our own bundled rootbuilder.py
+            if (entryName == QStringLiteral("rootbuilder.py"))
+                continue;
+            conflict = true;
+        }
+
+        if (conflict) {
+            QDir().mkpath(disabledDir);
+            QString dst = disabledDir + QStringLiteral("/") + entryName;
+            if (QFile::rename(entry.absoluteFilePath(), dst)) {
+                qInfo("Root Builder: moved incompatible third-party plugin "
+                      "'%s' to DisabledPlugins/.",
+                      qUtf8Printable(entryName));
+            } else {
+                qWarning("Root Builder: failed to move third-party plugin "
+                         "'%s' to DisabledPlugins/.",
+                         qUtf8Printable(entryName));
+            }
+        }
+    }
+}
+
+// ============================================================================
+// File helpers
+// ============================================================================
+
+QString RootBuilderNative::findRootDir(const QString& modPath)
+{
+    QDir dir(modPath);
+    const auto entries =
+        dir.entryInfoList(QDir::Dirs | QDir::NoDotAndDotDot);
+    for (const auto& entry : entries) {
+        if (entry.fileName().compare(QStringLiteral("root"),
+                                     Qt::CaseInsensitive) == 0) {
+            return entry.absoluteFilePath();
+        }
+    }
+    return QString();
+}
+
+void RootBuilderNative::ensureReadable(const QString& path)
+{
+    QFileInfo fi(path);
+    if (fi.exists() && !fi.isReadable()) {
+        QFile::setPermissions(path, fi.permissions() | QFileDevice::ReadOwner);
+    }
+}
+
+void RootBuilderNative::ensureWritable(const QString& path)
+{
+    QFileInfo fi(path);
+    if (fi.exists()) {
+        QFile::setPermissions(path, fi.permissions() | QFileDevice::WriteOwner);
+    }
+}
+
+void RootBuilderNative::reflinkCopy(const QString& src, const QString& dst)
+{
+    ensureReadable(src);
+
+    // Try cp --reflink=auto first
+    QProcess proc;
+    proc.setProgram(QStringLiteral("cp"));
+    proc.setArguments({QStringLiteral("--reflink=auto"), QStringLiteral("-f"),
+                       QStringLiteral("--"), src, dst});
+    proc.start();
+    if (proc.waitForFinished(10000) && proc.exitCode() == 0)
+        return;
+
+    // Fallback to QFile::copy (remove dst first since QFile::copy won't overwrite)
+    QFile::remove(dst);
+    if (QFile::copy(src, dst))
+        return;
+
+    qWarning("Root Builder: failed to copy %s -> %s",
+             qUtf8Printable(src), qUtf8Printable(dst));
+}
+
+bool RootBuilderNative::forceRemove(const QString& path)
+{
+    if (QFile::remove(path))
+        return true;
+
+    // Fix permissions and retry
+    ensureWritable(QFileInfo(path).absolutePath());
+    ensureWritable(path);
+    if (QFile::remove(path))
+        return true;
+
+    qWarning("Root Builder: could not remove %s", qUtf8Printable(path));
+    return false;
+}
+
+void RootBuilderNative::cleanupEmptyDirs(const QString& baseDir,
+                                         const QStringList& paths)
+{
+    std::set<QString> dirsToCheck;
+    for (const auto& path : paths) {
+        QString parent = QFileInfo(path).absolutePath();
+        while (!parent.isEmpty() && parent != baseDir) {
+            // Check samefile
+            QFileInfo parentInfo(parent);
+            QFileInfo baseInfo(baseDir);
+            if (parentInfo.absoluteFilePath() == baseInfo.absoluteFilePath())
+                break;
+            dirsToCheck.insert(parent);
+            parent = QFileInfo(parent).absolutePath();
+        }
+    }
+
+    // Sort by length descending (deepest first)
+    QStringList sorted(dirsToCheck.begin(), dirsToCheck.end());
+    std::sort(sorted.begin(), sorted.end(),
+              [](const QString& a, const QString& b) {
+                  return a.length() > b.length();
+              });
+
+    for (const auto& d : sorted) {
+        QDir dir(d);
+        if (dir.exists() && dir.isEmpty())
+            dir.rmdir(QStringLiteral("."));
+    }
+}
+
+// ============================================================================
+// Build
+// ============================================================================
+
+int RootBuilderNative::build() const
+{
+    auto* game = m_organizer->managedGame();
+    if (!game)
+        return 0;
+
+    QString gameDir = game->gameDirectory().absolutePath();
+    QString storage = storageDir();
+    auto* modList   = m_organizer->modList();
+    QString mode    = loadSettings().value(QStringLiteral("mode"))
+                          .toString(QStringLiteral("copy"));
+
+    // Clear any previous deployment first
+    QJsonObject existingManifest = loadManifest();
+    if (!existingManifest.isEmpty())
+        const_cast<RootBuilderNative*>(this)->clear();
+
+    QJsonArray deployed;
+    QJsonObject backups;
+    QSet<QString> deployedSet;
+
+    QStringList mods = modList->allModsByProfilePriority();
+    for (const auto& modName : mods) {
+        if (!(modList->state(modName) & MOBase::IModList::STATE_ACTIVE))
+            continue;
+
+        auto* mod = modList->getMod(modName);
+        if (!mod)
+            continue;
+        if (mod->isSeparator() || mod->isBackup() || mod->isForeign())
+            continue;
+
+        QString modPath = mod->absolutePath();
+        QString rootDir = findRootDir(modPath);
+        if (rootDir.isEmpty())
+            continue;
+
+        QDirIterator it(rootDir, QDir::Files, QDirIterator::Subdirectories);
+        while (it.hasNext()) {
+            it.next();
+            QString srcFile = it.filePath();
+            QString rel     = QDir(rootDir).relativeFilePath(srcFile);
+            QString dst     = gameDir + QStringLiteral("/") + rel;
+
+            // Backup existing file if not already deployed by us
+            if (QFile::exists(dst) && !deployedSet.contains(dst)) {
+                QString bak =
+                    backupDir() + QStringLiteral("/") + rel;
+                QDir().mkpath(QFileInfo(bak).absolutePath());
+                ensureWritable(dst);
+                QFile::copy(dst, bak);
+                backups[dst] = bak;
+            }
+
+            QDir().mkpath(QFileInfo(dst).absolutePath());
+
+            // Remove existing file/symlink
+            if (QFileInfo::exists(dst) || QFileInfo(dst).isSymLink())
+                forceRemove(dst);
+
+            // In link mode, .exe and .dll must be copied (Wine resolves
+            // symlinked exe paths to the target, breaking sibling lookups)
+            QString ext = QFileInfo(srcFile).suffix().toLower();
+            if (mode == QStringLiteral("link") && ext != QStringLiteral("exe") &&
+                ext != QStringLiteral("dll")) {
+                QFile::link(srcFile, dst);
+            } else {
+                reflinkCopy(srcFile, dst);
+            }
+
+            if (!deployedSet.contains(dst)) {
+                deployed.append(dst);
+                deployedSet.insert(dst);
+            }
+        }
+    }
+
+    QJsonObject manifest;
+    manifest[QStringLiteral("deployed")] = deployed;
+    manifest[QStringLiteral("backups")]  = backups;
+    saveManifest(manifest);
+
+    return deployed.count();
+}
+
+// ============================================================================
+// Clear
+// ============================================================================
+
+int RootBuilderNative::clear() const
+{
+    auto* game = m_organizer->managedGame();
+    if (!game)
+        return 0;
+
+    QString gameDir = game->gameDirectory().absolutePath();
+    QString storage = storageDir();
+
+    QJsonObject manifest = loadManifest();
+    if (manifest.isEmpty())
+        return 0;
+
+    int count = 0;
+    QJsonArray deployedArr = manifest.value(QStringLiteral("deployed")).toArray();
+    QJsonObject backupsObj = manifest.value(QStringLiteral("backups")).toObject();
+
+    QStringList failed;
+    QStringList cleared;
+
+    // Remove deployed files
+    for (const auto& val : deployedArr) {
+        QString path = val.toString();
+        if (QFileInfo::exists(path) || QFileInfo(path).isSymLink()) {
+            if (forceRemove(path)) {
+                ++count;
+                cleared.append(path);
+            } else {
+                failed.append(path);
+            }
+        } else {
+            cleared.append(path);
+        }
+    }
+
+    // Restore backups
+    for (auto it = backupsObj.begin(); it != backupsObj.end(); ++it) {
+        QString dst = it.key();
+        QString bak = it.value().toString();
+        if (QFile::exists(bak)) {
+            QDir().mkpath(QFileInfo(dst).absolutePath());
+            ensureWritable(QFileInfo(dst).absolutePath());
+            if (QFileInfo::exists(dst) || QFileInfo(dst).isSymLink())
+                forceRemove(dst);
+            if (!QFile::rename(bak, dst)) {
+                qWarning("Root Builder: could not restore backup %s -> %s",
+                         qUtf8Printable(bak), qUtf8Printable(dst));
+            }
+        }
+    }
+
+    // Clean up backup dir
+    QString bDir = backupDir();
+    if (QFileInfo(bDir).isDir())
+        QDir(bDir).removeRecursively();
+
+    if (!failed.isEmpty()) {
+        // Update manifest to only contain files we couldn't remove
+        QJsonArray failedArr;
+        for (const auto& f : failed)
+            failedArr.append(f);
+
+        QJsonObject retryManifest;
+        retryManifest[QStringLiteral("deployed")] = failedArr;
+        retryManifest[QStringLiteral("backups")]  = QJsonObject();
+        saveManifest(retryManifest);
+
+        qWarning("Root Builder: %d file(s) could not be removed. "
+                 "They will be retried on next clear.",
+                 static_cast<int>(failed.size()));
+    } else {
+        removeManifest();
+    }
+
+    cleanupEmptyDirs(gameDir, cleared);
+    return count;
+}
diff --git a/libs/rootbuilder_native/src/rootbuilder.h b/libs/rootbuilder_native/src/rootbuilder.h
new file mode 100644
index 0000000..121bcc1
--- /dev/null
+++ b/libs/rootbuilder_native/src/rootbuilder.h
@@ -0,0 +1,79 @@
+#ifndef ROOTBUILDER_NATIVE_H
+#define ROOTBUILDER_NATIVE_H
+
+#include <uibase/iplugintool.h>
+
+#include <QJsonObject>
+#include <QString>
+
+class RootBuilderNative : public MOBase::IPluginTool
+{
+    Q_OBJECT
+    Q_INTERFACES(MOBase::IPlugin MOBase::IPluginTool)
+    Q_PLUGIN_METADATA(IID "com.tannin.ModOrganizer.PluginTool/1.0")
+
+public:
+    RootBuilderNative();
+
+    // IPlugin
+    bool init(MOBase::IOrganizer* organizer) override;
+    QString name() const override;
+    QString localizedName() const override;
+    QString author() const override;
+    QString description() const override;
+    MOBase::VersionInfo version() const override;
+    QList<MOBase::PluginSetting> settings() const override;
+    bool enabledByDefault() const override;
+
+    // IPluginTool
+    QString displayName() const override;
+    QString tooltip() const override;
+    QIcon icon() const override;
+
+public slots:
+    void display() const override;
+
+private:
+    // Storage paths
+    QString storageDir() const;
+    QString backupDir() const;
+    QString manifestPath() const;
+    QString settingsPath() const;
+
+    // Settings (own JSON, not pluginSetting)
+    QJsonObject loadSettings() const;
+    void saveSettings(const QJsonObject& settings) const;
+    bool isAutoEnabled() const;
+
+    // Manifest
+    QJsonObject loadManifest() const;
+    void saveManifest(const QJsonObject& manifest) const;
+    void removeManifest() const;
+
+    // Legacy migration
+    void migrateLegacy() const;
+
+    // Third-party conflict detection
+    void checkThirdPartyRootBuilder() const;
+
+    // Build / Clear
+    int build() const;
+    int clear() const;
+
+    // File operations
+    static QString findRootDir(const QString& modPath);
+    static void reflinkCopy(const QString& src, const QString& dst);
+    static void ensureReadable(const QString& path);
+    static void ensureWritable(const QString& path);
+    static bool forceRemove(const QString& path);
+    static void cleanupEmptyDirs(const QString& baseDir,
+                                 const QStringList& paths);
+
+    // Hooks
+    bool onAboutToRun(const QString& executable);
+    void onFinishedRun(const QString& executable, unsigned int exitCode);
+
+    MOBase::IOrganizer* m_organizer = nullptr;
+};
+
+#endif // ROOTBUILDER_NATIVE_H