chore: release v0.3.0

Import legacy SearchMyFiles settings once so the FolderScope identity change does not discard user profiles and preferences.

CHANGELOG.md

@@ -5,6 +5,37 @@ All notable changes to FolderScope are documented here.
 The project uses [Semantic Versioning](https://semver.org/). Release tags are
 formatted as `vMAJOR.MINOR.PATCH`.
 
+## [0.3.0] - 2026-07-26
+
+### Added
+
+- Added persistent input history for folder and wildcard fields in Search
+  Options.
+
+### Changed
+
+- Renamed the executable, desktop entry, icon, and application identity from
+  SearchMyFiles to FolderScope.
+- Preserved existing settings and search profiles when migrating to the new
+  application identity.
+- Kept the base-folder browser button compact so the input field uses the
+  available width.
+
+## [0.2.5] - 2026-07-26
+
+### Added
+
+- Added an optional strict byte-by-byte verification mode for duplicate files.
+
+### Changed
+
+- Accelerated duplicate detection with size grouping, sampled block hashes, and
+  full SHA-256 hashing only for remaining candidates.
+- Normalized overlapping search roots and deduplicated file candidates so a
+  path cannot be compared with itself.
+- Strengthened persistent cache invalidation with nanosecond timestamps and
+  filesystem identity.
+
 ## [0.2.4] - 2026-07-25
 
 ### Fixed
@@ -66,3 +97,5 @@ formatted as `vMAJOR.MINOR.PATCH`.
 [0.2.2]: https://gitea.forust.xyz/forust/folderscope/releases/tag/v0.2.2
 [0.2.3]: https://gitea.forust.xyz/forust/folderscope/releases/tag/v0.2.3
 [0.2.4]: https://gitea.forust.xyz/forust/folderscope/releases/tag/v0.2.4
+[0.2.5]: https://gitea.forust.xyz/forust/folderscope/releases/tag/v0.2.5
+[0.3.0]: https://gitea.forust.xyz/forust/folderscope/releases/tag/v0.3.0

CMakeLists.txt

@@ -22,19 +22,31 @@ target_link_libraries(folderscope_core PUBLIC Qt6::Core)
 target_compile_options(folderscope_core PRIVATE -Wall -Wextra -Wpedantic)
 target_include_directories(folderscope_core PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/src")
 
-qt_add_executable(searchmyfiles
+qt_add_executable(folderscope
     src/long_long_spin_box.cpp
     src/long_long_spin_box.h
     src/main.cpp
+    src/main_window.h
+    src/main_window.cpp
+    src/search_cache.h
+    src/search_cache.cpp
+    src/search_engine.h
+    src/search_engine.cpp
+    src/results_model.h
+    src/results_model.cpp
+    src/options_dialog.h
+    src/options_dialog.cpp
 )
 
-target_link_libraries(searchmyfiles PRIVATE folderscope_core Qt6::Widgets Qt6::Concurrent Qt6::DBus)
-target_compile_options(searchmyfiles PRIVATE -Wall -Wextra -Wpedantic)
-target_compile_definitions(searchmyfiles PRIVATE FOLDERSCOPE_VERSION="${PROJECT_VERSION}")
+target_link_libraries(folderscope PRIVATE folderscope_core Qt6::Widgets Qt6::Concurrent Qt6::DBus)
+target_compile_options(folderscope PRIVATE -Wall -Wextra -Wpedantic)
+target_compile_definitions(folderscope PRIVATE FOLDERSCOPE_VERSION="${PROJECT_VERSION}")
 
-install(TARGETS searchmyfiles RUNTIME DESTINATION bin)
-install(FILES packaging/searchmyfiles.desktop
+install(TARGETS folderscope RUNTIME DESTINATION bin)
+install(FILES packaging/folderscope.desktop
         DESTINATION share/applications)
+install(FILES packaging/folderscope.svg
+        DESTINATION share/icons/hicolor/scalable/apps)
 
 include(CTest)
 if (BUILD_TESTING)
@@ -47,6 +59,43 @@ if (BUILD_TESTING)
     target_compile_options(search_core_tests PRIVATE -Wall -Wextra -Wpedantic)
     add_test(NAME search-core COMMAND search_core_tests)
 
+    qt_add_executable(search_cache_tests
+        src/search_cache.cpp
+        src/search_cache.h
+        tests/search_cache_test.cpp
+    )
+    target_link_libraries(search_cache_tests PRIVATE folderscope_core Qt6::Test)
+    target_compile_options(search_cache_tests PRIVATE -Wall -Wextra -Wpedantic)
+    target_include_directories(search_cache_tests PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/src")
+    add_test(NAME search-cache COMMAND search_cache_tests)
+
+    qt_add_executable(search_engine_tests
+        src/search_cache.cpp
+        src/search_cache.h
+        src/search_engine.cpp
+        src/search_engine.h
+        tests/search_engine_test.cpp
+    )
+    target_link_libraries(search_engine_tests PRIVATE
+        folderscope_core Qt6::Concurrent Qt6::Test)
+    target_compile_options(search_engine_tests PRIVATE -Wall -Wextra -Wpedantic)
+    target_include_directories(search_engine_tests PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/src")
+    add_test(NAME search-engine COMMAND search_engine_tests)
+
+    qt_add_executable(options_dialog_tests
+        src/long_long_spin_box.cpp
+        src/long_long_spin_box.h
+        src/options_dialog.cpp
+        src/options_dialog.h
+        tests/options_dialog_test.cpp
+    )
+    target_link_libraries(options_dialog_tests PRIVATE
+        folderscope_core Qt6::Widgets Qt6::Test)
+    target_compile_options(options_dialog_tests PRIVATE -Wall -Wextra -Wpedantic)
+    target_include_directories(options_dialog_tests PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/src")
+    add_test(NAME options-dialog COMMAND options_dialog_tests)
+    set_tests_properties(options-dialog PROPERTIES ENVIRONMENT "QT_QPA_PLATFORM=offscreen")
+
     qt_add_executable(long_long_spin_box_tests
         src/long_long_spin_box.cpp
         src/long_long_spin_box.h

README.md

@@ -12,6 +12,7 @@ single window.
 - search across multiple root folders;
 - filter by name patterns, size, timestamps, and file attributes;
 - inspect duplicate files and files with matching names;
+- optionally verify duplicate matches byte by byte in strict mode;
 - search inside file contents, including text and hex;
 - reuse a persistent, automatically invalidated cache for content matches and
   duplicate hashes;
@@ -33,7 +34,7 @@ Requirements:
 ```bash
 cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
 cmake --build build -j
-./build/searchmyfiles
+./build/folderscope
 ```
 
 Run the automated tests:

VERSION

@@ -1 +1 @@
-0.2.4
+0.3.0

packaging/folderscope.desktop

@@ -1,9 +1,8 @@
 [Desktop Entry]
 Type=Application
-Name=SearchMyFiles
+Name=FolderScope
 Comment=Fast advanced file search
-Exec=searchmyfiles
-Icon=system-search
+Exec=folderscope
+Icon=folderscope
 Terminal=false
 Categories=Utility;FileTools;
-

packaging/folderscope.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" width="64" height="64">
+  <rect width="64" height="64" rx="8" fill="#3584e4"/>
+  <circle cx="28" cy="28" r="12" fill="none" stroke="#fff" stroke-width="3.5"/>
+  <line x1="36" y1="36" x2="50" y2="50" stroke="#fff" stroke-width="3.5" stroke-linecap="round"/>
+</svg>

src/main_window.h

@@ -0,0 +1,117 @@
+#pragma once
+
+#include <QAction>
+#include <QCheckBox>
+#include <QClipboard>
+#include <QCloseEvent>
+#include <QDBusConnection>
+#include <QDBusInterface>
+#include <QDBusMessage>
+#include <QDesktopServices>
+#include <QHeaderView>
+#include <QInputDialog>
+#include <QKeyEvent>
+#include <QLabel>
+#include <QMainWindow>
+#include <QMenu>
+#include <QMenuBar>
+#include <QMessageBox>
+#include <QMimeData>
+#include <QProgressBar>
+#include <QProcess>
+#include <QSettings>
+#include <QSortFilterProxyModel>
+#include <QStatusBar>
+#include <QTableView>
+#include <QThread>
+#include <QToolBar>
+#include <QUrl>
+
+#include <optional>
+
+#include "results_model.h"
+#include "search_core.h"
+
+class SearchEngine;
+class QTextEdit;
+
+class MainWindow final : public QMainWindow {
+    Q_OBJECT
+public:
+    MainWindow();
+    ~MainWindow() override;
+
+protected:
+    void closeEvent(QCloseEvent *event) override;
+    void keyPressEvent(QKeyEvent *event) override;
+
+signals:
+    void startRequested(const SearchOptions &options);
+    void stopRequested();
+    void clearCacheRequested();
+
+private slots:
+    void showOptions();
+    void refreshSearch();
+    void findText();
+    void findNext();
+    void copyInformation();
+    void explorerCopy();
+    void explorerCut();
+    void startCurrentSearch();
+    void searchFinished(const QVector<FileRecord> &results, const QString &message);
+    void openSelected();
+    void openFolder();
+    void openWith();
+    void selectInFileManager();
+    void moveToTrash();
+    void deleteSelected();
+    void renameSelected();
+    void showProperties();
+    void copyPaths();
+    void contextMenu(const QPoint &point);
+    void headerContextMenu(const QPoint &point);
+    void exportResults();
+
+private:
+    std::optional<FileRecord> currentRecord() const;
+    QStringList actionChoices() const;
+    void executeConfiguredAction(const QString &action);
+    QString sizeUnitName() const;
+    int sizeUnitFromName(const QString &name) const;
+    void applyDisplayOptions();
+    void saveUiSettings();
+    QStringList selectedPaths() const;
+    void saveOptions();
+    void updateStaleSearchWarning();
+    void loadOptions();
+
+    SearchOptions options_;
+    ResultsModel *model_{};
+    QSortFilterProxyModel *proxy_{};
+    QTableView *table_{};
+    QAction *searchAction_{};
+    QAction *stopAction_{};
+    QAction *refreshAction_{};
+    QLabel *staleSearchWarning_{};
+    QProgressBar *progress_{};
+    QThread workerThread_;
+    SearchEngine *engine_{};
+    std::optional<SearchOptions> lastSearchOptions_;
+    QString findQuery_;
+    QString summarySizeUnitName_ = QStringLiteral("Automatic");
+    QString doubleClickAction_ = QStringLiteral("Open Properties Window");
+    QString enterKeyAction_ = QStringLiteral("Open Selected File");
+    int sizeUnit_ = 0;
+    int duplicateColorSet_ = 1;
+    bool showGmt_ = false;
+    bool markDuplicates_ = true;
+    bool addExportHeader_ = true;
+    bool focusOnSearchStart_ = true;
+    bool focusOnSearchEnd_ = true;
+    bool autoSizeOnSearchEnd_ = false;
+    bool showGrid_ = true;
+    bool showTooltips_ = true;
+    bool isSearching_ = false;
+    bool isStopping_ = false;
+};

src/options_dialog.cpp

@@ -0,0 +1,488 @@
+#include "options_dialog.h"
+
+#include <QDialogButtonBox>
+#include <QDropEvent>
+#include <QEvent>
+#include <QFileDialog>
+#include <QInputDialog>
+#include <QMessageBox>
+#include <QMimeData>
+#include <QSettings>
+#include <QSizePolicy>
+
+#include "long_long_spin_box.h"
+
+OptionsDialog::OptionsDialog(const SearchOptions &o, QWidget *parent) : QDialog(parent)
+{
+    setWindowTitle(tr("Search Options"));
+    resize(760, 560);
+    setupUi(o);
+}
+
+void OptionsDialog::setupUi(const SearchOptions &o)
+{
+    auto *layout = new QVBoxLayout(this);
+
+    auto *profileRow = new QWidget;
+    auto *profileLayout = new QHBoxLayout(profileRow);
+    profileLayout->setContentsMargins(0, 0, 0, 0);
+    profileCombo_ = new QComboBox;
+    profileCombo_->setEditable(false);
+    profileCombo_->addItem(tr("(default)"));
+    profileCombo_->setMinimumWidth(200);
+    {
+        QSettings settings;
+        settings.beginGroup(QStringLiteral("profiles"));
+        const QStringList profiles = settings.childGroups();
+        for (const QString &name : profiles)
+            profileCombo_->addItem(name);
+        settings.endGroup();
+    }
+    auto *saveBtn = new QPushButton(tr("Save Profile…"));
+    auto *loadBtn = new QPushButton(tr("Load Profile"));
+    auto *deleteBtn = new QPushButton(tr("Delete Profile"));
+    profileLayout->addWidget(new QLabel(tr("Profile:")));
+    profileLayout->addWidget(profileCombo_);
+    profileLayout->addWidget(saveBtn);
+    profileLayout->addWidget(loadBtn);
+    profileLayout->addWidget(deleteBtn);
+    layout->addWidget(profileRow);
+
+    connect(saveBtn, &QPushButton::clicked, this, &OptionsDialog::saveProfile);
+    connect(loadBtn, &QPushButton::clicked, this, &OptionsDialog::loadProfile);
+    connect(deleteBtn, &QPushButton::clicked, this, [this] {
+        const QString name = profileCombo_->currentText();
+        if (name.isEmpty() || name == tr("(default)"))
+            return;
+        if (QMessageBox::question(this, tr("Delete Profile"),
+                tr("Delete profile \"%1\"?").arg(name))
+                != QMessageBox::Yes)
+            return;
+        QSettings settings;
+        settings.beginGroup(QStringLiteral("profiles"));
+        settings.remove(name);
+        settings.endGroup();
+        profileCombo_->removeItem(profileCombo_->currentIndex());
+    });
+
+    auto *modeGroup = new QGroupBox(tr("Search mode"));
+    auto *modeLayout = new QHBoxLayout(modeGroup);
+    mode_ = new QComboBox;
+    mode_->addItems({tr("Standard search"), tr("Duplicates search"), tr("Non-Duplicates search"),
+                     tr("Summary"), tr("Duplicate names search")});
+    mode_->setCurrentText(o.mode);
+    duplicateMode_ = new QComboBox;
+    duplicateMode_->addItems({tr("All files and folders"), tr("Only files"),
+                              tr("Only identical content"), tr("Only non-identical content")});
+    duplicateMode_->setCurrentText(o.duplicateNameMode);
+    duplicateWithoutExtension_ = new QCheckBox(tr("Compare names without extension"));
+    duplicateWithoutExtension_->setChecked(o.duplicateNameWithoutExtension);
+    modeLayout->addWidget(mode_);
+    modeLayout->addWidget(new QLabel(tr("Duplicate-name mode:")));
+    modeLayout->addWidget(duplicateMode_);
+    modeLayout->addWidget(duplicateWithoutExtension_);
+    layout->addWidget(modeGroup);
+
+    auto *tabs = new QTabWidget;
+    layout->addWidget(tabs);
+
+    auto *filesPage = new QWidget;
+    auto *filesForm = new QFormLayout(filesPage);
+    roots_ = historyCombo(QStringLiteral("roots"), o.roots);
+    roots_->lineEdit()->setAcceptDrops(true);
+    roots_->setToolTip(tr("Drop folders here from your file manager"));
+    roots_->lineEdit()->installEventFilter(this);
+    auto *rootRow = new QWidget;
+    auto *rootLayout = new QHBoxLayout(rootRow);
+    rootLayout->setContentsMargins(0, 0, 0, 0);
+    rootLayout->addWidget(roots_);
+    auto *browse = new QPushButton(tr("Browse…"));
+    browse->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+    rootLayout->addWidget(browse);
+    rootLayout->setStretch(0, 1);
+    filesForm->addRow(tr("Base folders (separate with ;):"), rootRow);
+    fileMasks_ = addHistoryCombo(filesForm, tr("Files wildcard:"),
+                                 QStringLiteral("fileWildcards"), o.fileWildcards);
+    subfolderMasks_ = addHistoryCombo(filesForm, tr("Subfolders wildcard:"),
+                                      QStringLiteral("subfolderWildcards"), o.subfolderWildcards);
+    excludeFiles_ = addHistoryCombo(filesForm, tr("Exclude files:"),
+                                    QStringLiteral("excludeFiles"), o.excludeFiles);
+    excludeFolders_ = addHistoryCombo(filesForm, tr("Exclude folders:"),
+                                      QStringLiteral("excludeFolders"), o.excludeFolders);
+    includeFolders_ = addHistoryCombo(filesForm, tr("Include only folders:"),
+                                      QStringLiteral("includeFolders"), o.includeFolders);
+    recursive_ = new QCheckBox(tr("Search subfolders")); recursive_->setChecked(o.recursive);
+    findFiles_ = new QCheckBox(tr("Find files")); findFiles_->setChecked(o.findFiles);
+    findFolders_ = new QCheckBox(tr("Find folders")); findFolders_->setChecked(o.findFolders);
+    followLinks_ = new QCheckBox(tr("Follow symbolic links")); followLinks_->setChecked(o.followLinks);
+    retrieveOwner_ = new QCheckBox(tr("Retrieve file owner (slower)")); retrieveOwner_->setChecked(o.retrieveOwner);
+    accurateProgress_ = new QCheckBox(tr("Count files first for accurate progress"));
+    accurateProgress_->setChecked(o.accurateProgress);
+    useCache_ = new QCheckBox(tr("Use persistent cache for hashes and content searches"));
+    useCache_->setChecked(o.useCache);
+    strictDuplicateComparison_ =
+        new QCheckBox(tr("Strict duplicate comparison (byte by byte)"));
+    strictDuplicateComparison_->setObjectName(
+        QStringLiteral("strictDuplicateComparison"));
+    strictDuplicateComparison_->setChecked(o.strictDuplicateComparison);
+    maxDepth_ = new QSpinBox; maxDepth_->setRange(0, 1024); maxDepth_->setValue(o.maxDepth);
+    maxDepth_->setSpecialValueText(tr("Unlimited"));
+    maxResults_ = new QSpinBox; maxResults_->setRange(0, 100'000'000); maxResults_->setValue(o.maxResults);
+    maxResults_->setSpecialValueText(tr("Unlimited"));
+    filesForm->addRow(recursive_);
+    filesForm->addRow(tr("Subfolders depth:"), maxDepth_);
+    filesForm->addRow(findFiles_);
+    filesForm->addRow(findFolders_);
+    filesForm->addRow(followLinks_);
+    filesForm->addRow(retrieveOwner_);
+    filesForm->addRow(accurateProgress_);
+    filesForm->addRow(useCache_);
+    filesForm->addRow(strictDuplicateComparison_);
+    filesForm->addRow(tr("Stop after finding:"), maxResults_);
+    tabs->addTab(filesPage, tr("Files & folders"));
+
+    auto *contentPage = new QWidget;
+    auto *contentForm = new QFormLayout(contentPage);
+    contains_ = new QTextEdit(o.contains);
+    contains_->setMaximumHeight(110);
+    contentForm->addRow(tr("File contains:"), contains_);
+    binary_ = new QCheckBox(tr("Binary search (hex bytes, e.g. A2 C5 2F)")); binary_->setChecked(o.binary);
+    multiple_ = new QCheckBox(tr("Search multiple values (comma separated)")); multiple_->setChecked(o.multipleValues);
+    multipleMode_ = new QComboBox; multipleMode_->addItems({tr("Or"), tr("And")});
+    multipleMode_->setCurrentIndex(o.multipleAnd ? 1 : 0);
+    caseSensitive_ = new QCheckBox(tr("Case sensitive")); caseSensitive_->setChecked(o.caseSensitive);
+    contentForm->addRow(binary_);
+    contentForm->addRow(multiple_);
+    contentForm->addRow(tr("Multiple values match:"), multipleMode_);
+    contentForm->addRow(caseSensitive_);
+    tabs->addTab(contentPage, tr("File contents"));
+
+    auto *filterPage = new QWidget;
+    auto *filterForm = new QFormLayout(filterPage);
+    minSize_ = sizeSpin(o.minSize);
+    maxSize_ = sizeSpin(o.maxSize);
+    maxSize_->setSuffix(tr(" bytes (0 = any)"));
+    filterForm->addRow(tr("Minimum size:"), minSize_);
+    filterForm->addRow(tr("Maximum size:"), maxSize_);
+    timeField_ = new QComboBox;
+    timeField_->addItems({tr("Modified time"), tr("Accessed time"), tr("Metadata changed time")});
+    timeField_->setCurrentText(o.timeField);
+    filterForm->addRow(tr("Time field:"), timeField_);
+    lastMinutes_ = new QSpinBox;
+    lastMinutes_->setRange(0, 10'000'000);
+    lastMinutes_->setSuffix(tr(" minutes (0 = any)"));
+    lastMinutes_->setValue(o.lastMinutes);
+    filterForm->addRow(tr("Within last:"), lastMinutes_);
+    minTime_ = new QLineEdit(o.minTime ? QDateTime::fromSecsSinceEpoch(o.minTime).toString(Qt::ISODate) : QString{});
+    maxTime_ = new QLineEdit(o.maxTime ? QDateTime::fromSecsSinceEpoch(o.maxTime).toString(Qt::ISODate) : QString{});
+    minTime_->setPlaceholderText(tr("YYYY-MM-DDTHH:MM:SS"));
+    maxTime_->setPlaceholderText(tr("YYYY-MM-DDTHH:MM:SS"));
+    filterForm->addRow(tr("From time:"), minTime_);
+    filterForm->addRow(tr("To time:"), maxTime_);
+    hidden_ = attrCombo(o.hidden);
+    readonly_ = attrCombo(o.readonly);
+    executable_ = attrCombo(o.executable);
+    filterForm->addRow(tr("Hidden:"), hidden_);
+    filterForm->addRow(tr("Read-only:"), readonly_);
+    filterForm->addRow(tr("Executable:"), executable_);
+    tabs->addTab(filterPage, tr("Size, time & attributes"));
+
+    auto *buttons = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel);
+    connect(buttons, &QDialogButtonBox::accepted, this, &OptionsDialog::accept);
+    connect(buttons, &QDialogButtonBox::rejected, this, &QDialog::reject);
+    connect(browse, &QPushButton::clicked, this, [this] {
+        const QStringList existingFolders = patterns(roots_->currentText());
+        const QString startFolder = existingFolders.isEmpty()
+            ? QDir::homePath() : existingFolders.constLast();
+        const QString folder = QFileDialog::getExistingDirectory(
+            this, tr("Choose base folder"), startFolder);
+        if (folder.isEmpty())
+            return;
+
+        QStringList folders = existingFolders;
+        const QString cleanPath = QDir::cleanPath(folder);
+        if (!folders.contains(cleanPath))
+            folders.push_back(cleanPath);
+        roots_->setEditText(folders.join(u';'));
+    });
+    layout->addWidget(buttons);
+}
+
+SearchOptions OptionsDialog::options() const
+{
+    SearchOptions o;
+    o.roots = roots_->currentText();
+    o.fileWildcards = fileMasks_->currentText();
+    o.subfolderWildcards = subfolderMasks_->currentText();
+    o.excludeFiles = excludeFiles_->currentText();
+    o.excludeFolders = excludeFolders_->currentText();
+    o.includeFolders = includeFolders_->currentText();
+    o.contains = contains_->toPlainText();
+    o.binary = binary_->isChecked();
+    o.multipleValues = multiple_->isChecked();
+    o.multipleAnd = multipleMode_->currentIndex() == 1;
+    o.caseSensitive = caseSensitive_->isChecked();
+    o.minSize = minSize_->value();
+    o.maxSize = maxSize_->value();
+    o.timeField = timeField_->currentText();
+    o.lastMinutes = lastMinutes_->value();
+    o.minTime = dateValue(minTime_);
+    o.maxTime = dateValue(maxTime_);
+    o.recursive = recursive_->isChecked();
+    o.findFiles = findFiles_->isChecked();
+    o.findFolders = findFolders_->isChecked();
+    o.followLinks = followLinks_->isChecked();
+    o.retrieveOwner = retrieveOwner_->isChecked();
+    o.accurateProgress = accurateProgress_->isChecked();
+    o.useCache = useCache_->isChecked();
+    o.strictDuplicateComparison = strictDuplicateComparison_->isChecked();
+    o.maxDepth = maxDepth_->value();
+    o.maxResults = maxResults_->value();
+    o.mode = mode_->currentText();
+    o.duplicateNameMode = duplicateMode_->currentText();
+    o.duplicateNameWithoutExtension = duplicateWithoutExtension_->isChecked();
+    o.hidden = hidden_->currentText();
+    o.readonly = readonly_->currentText();
+    o.executable = executable_->currentText();
+    return o;
+}
+
+void OptionsDialog::accept()
+{
+    if (!validateDate(minTime_, tr("From time"))
+        || !validateDate(maxTime_, tr("To time")))
+        return;
+    rememberHistory(QStringLiteral("roots"), roots_->currentText());
+    rememberHistory(QStringLiteral("fileWildcards"), fileMasks_->currentText());
+    rememberHistory(QStringLiteral("subfolderWildcards"), subfolderMasks_->currentText());
+    rememberHistory(QStringLiteral("excludeFiles"), excludeFiles_->currentText());
+    rememberHistory(QStringLiteral("excludeFolders"), excludeFolders_->currentText());
+    rememberHistory(QStringLiteral("includeFolders"), includeFolders_->currentText());
+    QDialog::accept();
+}
+
+QComboBox *OptionsDialog::historyCombo(const QString &key, const QString &value)
+{
+    auto *combo = new QComboBox;
+    combo->setEditable(true);
+    combo->setInsertPolicy(QComboBox::NoInsert);
+    combo->setObjectName(QStringLiteral("history%1").arg(key));
+
+    QSettings settings;
+    const QStringList history = settings.value(QStringLiteral("inputHistory/%1").arg(key)).toStringList();
+    combo->addItems(history);
+    combo->setEditText(value);
+    return combo;
+}
+
+QComboBox *OptionsDialog::addHistoryCombo(QFormLayout *layout, const QString &label,
+                                          const QString &key, const QString &value)
+{
+    auto *combo = historyCombo(key, value);
+    layout->addRow(label, combo);
+    return combo;
+}
+
+LongLongSpinBox *OptionsDialog::sizeSpin(qint64 value)
+{
+    auto *spin = new LongLongSpinBox;
+    spin->setRange(0, std::numeric_limits<qint64>::max());
+    spin->setSuffix(QObject::tr(" bytes"));
+    spin->setValue(value);
+    return spin;
+}
+
+qint64 OptionsDialog::dateValue(const QLineEdit *edit)
+{
+    qint64 seconds = 0;
+    parseOptionalIsoDate(edit->text(), seconds);
+    return seconds;
+}
+
+bool OptionsDialog::validateDate(QLineEdit *edit, const QString &label)
+{
+    qint64 seconds = 0;
+    if (parseOptionalIsoDate(edit->text(), seconds))
+        return true;
+    QMessageBox::warning(
+        this, tr("Invalid date"),
+        tr("%1 must be a valid ISO date and time, for example:\n2026-07-25T20:30:00")
+            .arg(label));
+    edit->setFocus();
+    edit->selectAll();
+    return false;
+}
+
+void OptionsDialog::rememberHistory(const QString &key, const QString &value)
+{
+    if (value.isEmpty())
+        return;
+
+    QSettings settings;
+    const QString settingsKey = QStringLiteral("inputHistory/%1").arg(key);
+    QStringList history = settings.value(settingsKey).toStringList();
+    history.removeAll(value);
+    history.prepend(value);
+    constexpr qsizetype maxHistoryEntries = 20;
+    if (history.size() > maxHistoryEntries)
+        history.erase(history.begin() + maxHistoryEntries, history.end());
+    settings.setValue(settingsKey, history);
+}
+
+QComboBox *OptionsDialog::attrCombo(const QString &value)
+{
+    auto *combo = new QComboBox;
+    combo->addItems({QObject::tr("Any"), QObject::tr("Yes"), QObject::tr("No")});
+    combo->setCurrentText(value);
+    return combo;
+}
+
+bool OptionsDialog::eventFilter(QObject *obj, QEvent *event)
+{
+    if (obj == roots_->lineEdit() && event->type() == QEvent::DragEnter) {
+        auto *dragEnter = static_cast<QDragEnterEvent *>(event);
+        if (dragEnter->mimeData()->hasUrls()) {
+            dragEnter->acceptProposedAction();
+            return true;
+        }
+        return false;
+    }
+    if (obj == roots_->lineEdit() && event->type() == QEvent::Drop) {
+        auto *drop = static_cast<QDropEvent *>(event);
+        if (!drop->mimeData()->hasUrls())
+            return false;
+        QStringList folders = patterns(roots_->currentText());
+        for (const QUrl &url : drop->mimeData()->urls()) {
+            if (!url.isLocalFile())
+                continue;
+            const QString cleanPath = QDir::cleanPath(url.toLocalFile());
+            if (QFileInfo::exists(cleanPath) && !folders.contains(cleanPath))
+                folders.append(cleanPath);
+        }
+        roots_->setEditText(folders.join(u';'));
+        drop->acceptProposedAction();
+        return true;
+    }
+    return QDialog::eventFilter(obj, event);
+}
+
+void OptionsDialog::saveProfile()
+{
+    bool ok = false;
+    const QString name = QInputDialog::getText(
+        this, tr("Save Profile"), tr("Profile name:"), QLineEdit::Normal, QString{}, &ok);
+    if (!ok || name.trimmed().isEmpty())
+        return;
+
+    const QString profileName = name.trimmed();
+    const SearchOptions opt = options();
+
+    QSettings settings;
+    settings.beginGroup(QStringLiteral("profiles"));
+    settings.beginGroup(profileName);
+
+    auto save = [&](const char *key, const QString &val) { settings.setValue(QString::fromLatin1(key), val); };
+    auto saveBool = [&](const char *key, bool val) { settings.setValue(QString::fromLatin1(key), val); };
+    auto saveInt = [&](const char *key, int val) { settings.setValue(QString::fromLatin1(key), val); };
+    auto saveLong = [&](const char *key, qint64 val) { settings.setValue(QString::fromLatin1(key), val); };
+
+    save("roots", opt.roots);
+    save("fileWildcards", opt.fileWildcards);
+    save("subfolderWildcards", opt.subfolderWildcards);
+    save("excludeFiles", opt.excludeFiles);
+    save("excludeFolders", opt.excludeFolders);
+    save("includeFolders", opt.includeFolders);
+    save("contains", opt.contains);
+    save("mode", opt.mode);
+    save("duplicateNameMode", opt.duplicateNameMode);
+    save("timeField", opt.timeField);
+    save("hidden", opt.hidden);
+    save("readonly", opt.readonly);
+    save("executable", opt.executable);
+
+    saveBool("binary", opt.binary);
+    saveBool("multipleValues", opt.multipleValues);
+    saveBool("multipleAnd", opt.multipleAnd);
+    saveBool("caseSensitive", opt.caseSensitive);
+    saveBool("recursive", opt.recursive);
+    saveBool("findFiles", opt.findFiles);
+    saveBool("findFolders", opt.findFolders);
+    saveBool("followLinks", opt.followLinks);
+    saveBool("retrieveOwner", opt.retrieveOwner);
+    saveBool("accurateProgress", opt.accurateProgress);
+    saveBool("useCache", opt.useCache);
+    saveBool("duplicateNameWithoutExtension", opt.duplicateNameWithoutExtension);
+    saveBool("strictDuplicateComparison", opt.strictDuplicateComparison);
+
+    saveInt("lastMinutes", opt.lastMinutes);
+    saveInt("maxDepth", opt.maxDepth);
+    saveInt("maxResults", opt.maxResults);
+
+    saveLong("minSize", opt.minSize);
+    saveLong("maxSize", opt.maxSize);
+    saveLong("minTime", opt.minTime);
+    saveLong("maxTime", opt.maxTime);
+
+    settings.endGroup();
+    settings.endGroup();
+
+    if (profileCombo_->findText(profileName) < 0)
+        profileCombo_->addItem(profileName);
+    profileCombo_->setCurrentText(profileName);
+}
+
+void OptionsDialog::loadProfile()
+{
+    const QString name = profileCombo_->currentText();
+    if (name.isEmpty() || name == tr("(default)"))
+        return;
+
+    QSettings settings;
+    settings.beginGroup(QStringLiteral("profiles"));
+    settings.beginGroup(name);
+
+    auto load = [&](const char *key) { return settings.value(QString::fromLatin1(key)).toString(); };
+    auto loadBool = [&](const char *key, bool def) { return settings.value(QString::fromLatin1(key), def).toBool(); };
+    auto loadInt = [&](const char *key, int def) { return settings.value(QString::fromLatin1(key), def).toInt(); };
+    auto loadLong = [&](const char *key, qint64 def) { return settings.value(QString::fromLatin1(key), def).toLongLong(); };
+
+    roots_->setEditText(load("roots"));
+    fileMasks_->setEditText(load("fileWildcards"));
+    subfolderMasks_->setEditText(load("subfolderWildcards"));
+    excludeFiles_->setEditText(load("excludeFiles"));
+    excludeFolders_->setEditText(load("excludeFolders"));
+    includeFolders_->setEditText(load("includeFolders"));
+    contains_->setText(load("contains"));
+    binary_->setChecked(loadBool("binary", false));
+    multiple_->setChecked(loadBool("multipleValues", false));
+    multipleMode_->setCurrentIndex(loadBool("multipleAnd", false) ? 1 : 0);
+    caseSensitive_->setChecked(loadBool("caseSensitive", false));
+    minSize_->setValue(loadLong("minSize", 0));
+    maxSize_->setValue(loadLong("maxSize", 0));
+    timeField_->setCurrentText(load("timeField"));
+    lastMinutes_->setValue(loadInt("lastMinutes", 0));
+    minTime_->setText(loadLong("minTime", 0)
+        ? QDateTime::fromSecsSinceEpoch(loadLong("minTime", 0)).toString(Qt::ISODate) : QString{});
+    maxTime_->setText(loadLong("maxTime", 0)
+        ? QDateTime::fromSecsSinceEpoch(loadLong("maxTime", 0)).toString(Qt::ISODate) : QString{});
+    recursive_->setChecked(loadBool("recursive", true));
+    findFiles_->setChecked(loadBool("findFiles", true));
+    findFolders_->setChecked(loadBool("findFolders", false));
+    followLinks_->setChecked(loadBool("followLinks", false));
+    retrieveOwner_->setChecked(loadBool("retrieveOwner", false));
+    accurateProgress_->setChecked(loadBool("accurateProgress", true));
+    useCache_->setChecked(loadBool("useCache", true));
+    strictDuplicateComparison_->setChecked(
+        loadBool("strictDuplicateComparison", false));
+    maxDepth_->setValue(loadInt("maxDepth", 0));
+    maxResults_->setValue(loadInt("maxResults", 0));
+    mode_->setCurrentText(load("mode"));
+    duplicateMode_->setCurrentText(load("duplicateNameMode"));
+    duplicateWithoutExtension_->setChecked(loadBool("duplicateNameWithoutExtension", false));
+    hidden_->setCurrentText(load("hidden"));
+    readonly_->setCurrentText(load("readonly"));
+    executable_->setCurrentText(load("executable"));
+
+    settings.endGroup();
+    settings.endGroup();
+}

src/options_dialog.h

@@ -0,0 +1,79 @@
+#pragma once
+
+#include <QCheckBox>
+#include <QComboBox>
+#include <QDialog>
+#include <QFormLayout>
+#include <QGroupBox>
+#include <QLabel>
+#include <QLineEdit>
+#include <QPushButton>
+#include <QSpinBox>
+#include <QTabWidget>
+#include <QTextEdit>
+#include <QVBoxLayout>
+
+#include "search_core.h"
+
+class LongLongSpinBox;
+
+class OptionsDialog final : public QDialog {
+    Q_OBJECT
+public:
+    explicit OptionsDialog(const SearchOptions &o, QWidget *parent = nullptr);
+
+    SearchOptions options() const;
+
+protected:
+    void accept() override;
+
+private:
+    bool eventFilter(QObject *obj, QEvent *event) override;
+    static QComboBox *historyCombo(const QString &key, const QString &value);
+    static QComboBox *addHistoryCombo(QFormLayout *layout, const QString &label,
+                                      const QString &key, const QString &value);
+    static LongLongSpinBox *sizeSpin(qint64 value);
+    static qint64 dateValue(const QLineEdit *edit);
+    bool validateDate(QLineEdit *edit, const QString &label);
+    void rememberHistory(const QString &key, const QString &value);
+    static QComboBox *attrCombo(const QString &value);
+
+    void setupUi(const SearchOptions &o);
+    void saveProfile();
+    void loadProfile();
+
+    QComboBox *mode_{};
+    QComboBox *duplicateMode_{};
+    QCheckBox *duplicateWithoutExtension_{};
+    QComboBox *roots_{};
+    QComboBox *fileMasks_{};
+    QComboBox *subfolderMasks_{};
+    QComboBox *excludeFiles_{};
+    QComboBox *excludeFolders_{};
+    QComboBox *includeFolders_{};
+    QTextEdit *contains_{};
+    QCheckBox *binary_{};
+    QCheckBox *multiple_{};
+    QComboBox *multipleMode_{};
+    QCheckBox *caseSensitive_{};
+    LongLongSpinBox *minSize_{};
+    LongLongSpinBox *maxSize_{};
+    QComboBox *timeField_{};
+    QSpinBox *lastMinutes_{};
+    QLineEdit *minTime_{};
+    QLineEdit *maxTime_{};
+    QCheckBox *recursive_{};
+    QCheckBox *findFiles_{};
+    QCheckBox *findFolders_{};
+    QCheckBox *followLinks_{};
+    QCheckBox *retrieveOwner_{};
+    QCheckBox *accurateProgress_{};
+    QCheckBox *useCache_{};
+    QCheckBox *strictDuplicateComparison_{};
+    QSpinBox *maxDepth_{};
+    QSpinBox *maxResults_{};
+    QComboBox *hidden_{};
+    QComboBox *readonly_{};
+    QComboBox *executable_{};
+    QComboBox *profileCombo_{};
+};

src/results_model.cpp

@@ -0,0 +1,125 @@
+#include "results_model.h"
+
+#include <QDateTime>
+#include <QFileInfo>
+
+ResultsModel::ResultsModel(QObject *parent) : QAbstractTableModel(parent) {}
+
+int ResultsModel::rowCount(const QModelIndex &parent) const
+{
+    return parent.isValid() ? 0 : rows_.size();
+}
+
+int ResultsModel::columnCount(const QModelIndex &parent) const
+{
+    return parent.isValid() ? 0 : ColumnCount;
+}
+
+QVariant ResultsModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+    if (orientation != Qt::Horizontal)
+        return {};
+    if (role == Qt::ToolTipRole) {
+        if (section == DuplicateNumber)
+            return tr("Identifies one set of identical files");
+        if (section == DuplicateGroup)
+            return tr("Most-specific base folder wins; ties use newer files, then path. 1 = preferred copy to keep");
+        return {};
+    }
+    if (role != Qt::DisplayRole)
+        return {};
+    static const QStringList names{
+        tr("Filename"), tr("Folder"), tr("Size"), tr("Size On Disk"), tr("Modified Time"),
+        tr("Created Time"), tr("Last Accessed Time"), tr("Entry Modified Time"),
+        tr("Attributes"), tr("Extension"), tr("Duplicate Set"), tr("Keeper Priority"),
+        tr("Type"), tr("File Owner"), tr("Full Path")
+    };
+    return names.value(section);
+}
+
+QVariant ResultsModel::data(const QModelIndex &index, int role) const
+{
+    if (!index.isValid() || index.row() >= rows_.size())
+        return {};
+    const FileRecord &r = rows_[index.row()];
+    if (role == Qt::UserRole)
+        return r.path;
+    if (role == Qt::BackgroundRole && r.group && markDuplicates_) {
+        const int colorIndex = (r.group - 1) % 64;
+        return duplicateColorSet_ == 1
+            ? QColor::fromHsv((colorIndex * 137) % 360, 38 + (colorIndex % 3) * 8, 255)
+            : QColor::fromHsv((colorIndex * 137) % 360, 85, 205);
+    }
+    if (role == Qt::ForegroundRole && r.group && markDuplicates_)
+        return duplicateColorSet_ == 1 ? QColor(Qt::black) : QColor(Qt::white);
+    if (role == Qt::TextAlignmentRole && index.column() == Size)
+        return int(Qt::AlignRight | Qt::AlignVCenter);
+    if (role == Qt::EditRole) {
+        if (index.column() == Size) return r.size;
+        if (index.column() == SizeOnDisk) return r.sizeOnDisk;
+        if (index.column() == Modified) return r.modified;
+        if (index.column() == Created) return r.created;
+        if (index.column() == Accessed) return r.accessed;
+        if (index.column() == Changed) return r.changed;
+        if (index.column() == DuplicateNumber) return r.group;
+        if (index.column() == DuplicateGroup) return r.duplicateCopy;
+        return data(index, Qt::DisplayRole);
+    }
+    if (role != Qt::DisplayRole)
+        return {};
+    const auto time = [this](qint64 value) {
+        QDateTime dateTime = QDateTime::fromSecsSinceEpoch(value);
+        if (showGmt_)
+            dateTime = dateTime.toUTC();
+        return value ? dateTime.toString(QStringLiteral("yyyy-MM-dd HH:mm:ss"))
+                     : QString{};
+    };
+    switch (index.column()) {
+    case Name: return r.name;
+    case Folder: return r.folder;
+    case Size: return formattedSize(r.size);
+    case SizeOnDisk: return formattedSize(r.sizeOnDisk);
+    case Modified: return time(r.modified);
+    case Created: return time(r.created);
+    case Accessed: return time(r.accessed);
+    case Changed: return time(r.changed);
+    case Attributes: return r.attributes;
+    case Extension: return QFileInfo(r.name).suffix();
+    case DuplicateNumber: return r.group ? QVariant(r.group) : QVariant{};
+    case DuplicateGroup: return r.duplicateCopy ? QVariant(r.duplicateCopy) : QVariant{};
+    case Type: return r.type;
+    case Owner: return r.owner;
+    case FullPath: return r.path;
+    default: return {};
+    }
+}
+
+void ResultsModel::setRows(QVector<FileRecord> rows)
+{
+    beginResetModel();
+    rows_ = std::move(rows);
+    endResetModel();
+}
+
+void ResultsModel::setDisplayOptions(int sizeUnit, bool showGmt, bool markDuplicates, int colorSet)
+{
+    sizeUnit_ = sizeUnit;
+    showGmt_ = showGmt;
+    markDuplicates_ = markDuplicates;
+    duplicateColorSet_ = colorSet;
+    if (!rows_.isEmpty())
+        emit dataChanged(index(0, 0), index(rows_.size() - 1, ColumnCount - 1));
+}
+
+QString ResultsModel::formattedSize(qint64 bytes) const
+{
+    if (sizeUnit_ == 0)
+        return humanSize(bytes);
+    static const double divisors[]{1.0, 1024.0, 1024.0 * 1024.0, 1024.0 * 1024.0 * 1024.0};
+    static const char *units[]{"Bytes", "KB", "MB", "GB"};
+    const int index = std::clamp(sizeUnit_ - 1, 0, 3);
+    return index == 0
+        ? QStringLiteral("%1 Bytes").arg(bytes)
+        : QStringLiteral("%1 %2").arg(double(bytes) / divisors[index], 0, 'f', 2)
+              .arg(QString::fromLatin1(units[index]));
+}

src/results_model.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <QAbstractTableModel>
+#include <QColor>
+#include <QStringList>
+#include <QVariant>
+
+#include "search_core.h"
+
+class ResultsModel final : public QAbstractTableModel {
+    Q_OBJECT
+public:
+    enum Column { Name, Folder, Size, SizeOnDisk, Modified, Created, Accessed, Changed,
+                  Attributes, Extension, DuplicateNumber, DuplicateGroup, Type, Owner,
+                  FullPath, ColumnCount };
+
+    explicit ResultsModel(QObject *parent = nullptr);
+
+    int rowCount(const QModelIndex &parent = {}) const override;
+    int columnCount(const QModelIndex &parent = {}) const override;
+    QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+    QVariant data(const QModelIndex &index, int role) const override;
+
+    void setRows(QVector<FileRecord> rows);
+    const QVector<FileRecord> &rows() const { return rows_; }
+
+    void setDisplayOptions(int sizeUnit, bool showGmt, bool markDuplicates, int colorSet);
+
+private:
+    QString formattedSize(qint64 bytes) const;
+
+    QVector<FileRecord> rows_;
+    int sizeUnit_ = 0;
+    bool showGmt_ = false;
+    bool markDuplicates_ = true;
+    int duplicateColorSet_ = 1;
+};

src/search_cache.cpp

@@ -0,0 +1,193 @@
+#include "search_cache.h"
+
+#include <QDateTime>
+#include <QDataStream>
+#include <QDir>
+#include <QFile>
+#include <QSaveFile>
+#include <QStandardPaths>
+
+#include <algorithm>
+#include <utility>
+
+SearchCache::SearchCache(QString path)
+{
+    if (path.isEmpty()) {
+        const QString cacheRoot = QStandardPaths::writableLocation(QStandardPaths::CacheLocation);
+        QDir().mkpath(cacheRoot);
+        path_ = QDir(cacheRoot).filePath(QStringLiteral("search-cache-v1.dat"));
+    } else {
+        path_ = std::move(path);
+    }
+    load();
+}
+
+bool SearchCache::findSampleHash(const FileRecord &record, QByteArray &digest)
+{
+    if (!enabled_)
+        return false;
+    QMutexLocker lock(&mutex_);
+    auto it = entries_.find(record.path);
+    if (it == entries_.end() || !signatureMatches(*it, record)
+        || it->sampleSha256.isEmpty())
+        return false;
+    it->lastUsed = QDateTime::currentSecsSinceEpoch();
+    digest = it->sampleSha256;
+    return true;
+}
+
+void SearchCache::storeSampleHash(const FileRecord &record, const QByteArray &digest)
+{
+    if (!enabled_ || digest.isEmpty())
+        return;
+    QMutexLocker lock(&mutex_);
+    SearchCacheEntry &entry = currentEntry(record);
+    entry.sampleSha256 = digest;
+}
+
+bool SearchCache::findHash(const FileRecord &record, QByteArray &digest)
+{
+    if (!enabled_)
+        return false;
+    QMutexLocker lock(&mutex_);
+    auto it = entries_.find(record.path);
+    if (it == entries_.end() || !signatureMatches(*it, record) || it->sha256.isEmpty())
+        return false;
+    it->lastUsed = QDateTime::currentSecsSinceEpoch();
+    digest = it->sha256;
+    return true;
+}
+
+void SearchCache::storeHash(const FileRecord &record, const QByteArray &digest)
+{
+    if (!enabled_ || digest.isEmpty())
+        return;
+    QMutexLocker lock(&mutex_);
+    SearchCacheEntry &entry = currentEntry(record);
+    entry.sha256 = digest;
+}
+
+std::optional<bool> SearchCache::findContent(const FileRecord &record, const QByteArray &queryKey)
+{
+    if (!enabled_)
+        return std::nullopt;
+    QMutexLocker lock(&mutex_);
+    auto it = entries_.find(record.path);
+    if (it == entries_.end() || !signatureMatches(*it, record))
+        return std::nullopt;
+    const auto match = it->contentMatches.constFind(queryKey);
+    if (match == it->contentMatches.cend())
+        return std::nullopt;
+    it->lastUsed = QDateTime::currentSecsSinceEpoch();
+    return *match;
+}
+
+void SearchCache::storeContent(const FileRecord &record, const QByteArray &queryKey, bool matched)
+{
+    if (!enabled_)
+        return;
+    QMutexLocker lock(&mutex_);
+    SearchCacheEntry &entry = currentEntry(record);
+    entry.contentMatches.insert(queryKey, matched);
+}
+
+void SearchCache::save()
+{
+    if (!enabled_)
+        return;
+    QMutexLocker lock(&mutex_);
+    prune();
+    QSaveFile file(path_);
+    if (!file.open(QIODevice::WriteOnly))
+        return;
+    QDataStream stream(&file);
+    stream.setVersion(QDataStream::Qt_6_0);
+    stream << quint32(0x46534348) << quint32(2) << quint32(entries_.size());
+    for (auto it = entries_.cbegin(); it != entries_.cend(); ++it) {
+        stream << it.key() << it->size << it->modifiedNs << it->device << it->inode
+               << it->lastUsed << it->sampleSha256 << it->sha256;
+        stream << quint32(it->contentMatches.size());
+        for (auto match = it->contentMatches.cbegin(); match != it->contentMatches.cend(); ++match)
+            stream << match.key() << match.value();
+    }
+    if (stream.status() == QDataStream::Ok)
+        file.commit();
+}
+
+void SearchCache::clear()
+{
+    QMutexLocker lock(&mutex_);
+    entries_.clear();
+    QFile::remove(path_);
+}
+
+bool SearchCache::signatureMatches(const SearchCacheEntry &entry, const FileRecord &record)
+{
+    return entry.size == record.size
+        && entry.modifiedNs == record.modifiedNs
+        && entry.device == record.device
+        && entry.inode == record.inode;
+}
+
+SearchCacheEntry &SearchCache::currentEntry(const FileRecord &record)
+{
+    SearchCacheEntry &entry = entries_[record.path];
+    if (!signatureMatches(entry, record)) {
+        entry = {};
+        entry.size = record.size;
+        entry.modifiedNs = record.modifiedNs;
+        entry.device = record.device;
+        entry.inode = record.inode;
+    }
+    entry.lastUsed = QDateTime::currentSecsSinceEpoch();
+    return entry;
+}
+
+void SearchCache::load()
+{
+    QFile file(path_);
+    if (!file.open(QIODevice::ReadOnly))
+        return;
+    QDataStream stream(&file);
+    stream.setVersion(QDataStream::Qt_6_0);
+    quint32 magic = 0;
+    quint32 version = 0;
+    quint32 count = 0;
+    stream >> magic >> version >> count;
+    if (magic != 0x46534348 || version != 2 || count > 200'000)
+        return;
+    for (quint32 index = 0; index < count && stream.status() == QDataStream::Ok; ++index) {
+        QString path;
+        SearchCacheEntry entry;
+        quint32 contentCount = 0;
+        stream >> path >> entry.size >> entry.modifiedNs >> entry.device >> entry.inode
+               >> entry.lastUsed >> entry.sampleSha256 >> entry.sha256;
+        stream >> contentCount;
+        if (contentCount > 256)
+            return;
+        for (quint32 contentIndex = 0; contentIndex < contentCount; ++contentIndex) {
+            QByteArray key;
+            bool matched = false;
+            stream >> key >> matched;
+            entry.contentMatches.insert(key, matched);
+        }
+        entries_.insert(path, std::move(entry));
+    }
+    if (stream.status() != QDataStream::Ok)
+        entries_.clear();
+}
+
+void SearchCache::prune()
+{
+    constexpr qsizetype maxEntries = 100'000;
+    if (entries_.size() <= maxEntries)
+        return;
+    QVector<QPair<qint64, QString>> ages;
+    ages.reserve(entries_.size());
+    for (auto it = entries_.cbegin(); it != entries_.cend(); ++it)
+        ages.push_back({it->lastUsed, it.key()});
+    std::sort(ages.begin(), ages.end(),
+              [](const auto &left, const auto &right) { return left.first > right.first; });
+    for (qsizetype index = maxEntries; index < ages.size(); ++index)
+        entries_.remove(ages[index].second);
+}

src/search_cache.h

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <QByteArray>
+#include <QHash>
+#include <QMutex>
+#include <QString>
+
+#include "search_core.h"
+
+struct SearchCacheEntry {
+    qint64 size = -1;
+    qint64 modifiedNs = -1;
+    quint64 device = 0;
+    quint64 inode = 0;
+    qint64 lastUsed = 0;
+    QByteArray sampleSha256;
+    QByteArray sha256;
+    QHash<QByteArray, bool> contentMatches;
+};
+
+class SearchCache {
+public:
+    explicit SearchCache(QString path = {});
+
+    void setEnabled(bool enabled) { enabled_ = enabled; }
+    bool enabled() const { return enabled_; }
+
+    bool findSampleHash(const FileRecord &record, QByteArray &digest);
+    void storeSampleHash(const FileRecord &record, const QByteArray &digest);
+    bool findHash(const FileRecord &record, QByteArray &digest);
+    void storeHash(const FileRecord &record, const QByteArray &digest);
+    std::optional<bool> findContent(const FileRecord &record, const QByteArray &queryKey);
+    void storeContent(const FileRecord &record, const QByteArray &queryKey, bool matched);
+    void save();
+    void clear();
+
+private:
+    static bool signatureMatches(const SearchCacheEntry &entry, const FileRecord &record);
+    SearchCacheEntry &currentEntry(const FileRecord &record);
+    void load();
+    void prune();
+
+    QHash<QString, SearchCacheEntry> entries_;
+    QMutex mutex_;
+    QString path_;
+    bool enabled_ = true;
+};

src/search_core.cpp

@@ -2,11 +2,16 @@
 
 #include <QCryptographicHash>
 #include <QDateTime>
+#include <QDir>
 #include <QFile>
+#include <QFileInfo>
 #include <QRegularExpression>
+#include <QSet>
 
 #include <algorithm>
+#include <array>
 #include <pwd.h>
+#include <sys/stat.h>
 
 QStringList patterns(const QString &text)
 {
@@ -54,6 +59,129 @@ bool wildcardMatch(const QString &value, const QStringList &items, Qt::CaseSensi
     return false;
 }
 
+namespace {
+struct RootCandidate {
+    QString path;
+};
+
+bool isDescendantPath(const QString &parent, const QString &child,
+                      QString *relativePath = nullptr)
+{
+    const QString relative = QDir(parent).relativeFilePath(child);
+    const bool descendant = relative != QStringLiteral(".")
+        && relative != QStringLiteral("..")
+        && !relative.startsWith(QStringLiteral("../"))
+        && !QDir::isAbsolutePath(relative);
+    if (descendant && relativePath)
+        *relativePath = relative;
+    return descendant;
+}
+
+bool canCollapseInto(const RootCandidate &parent, const RootCandidate &child,
+                     const SearchOptions &options, const QStringList &excludedFolders,
+                     Qt::CaseSensitivity cs)
+{
+    if (!QFileInfo(parent.path).isDir())
+        return false;
+
+    QString relative;
+    if (!isDescendantPath(parent.path, child.path, &relative))
+        return false;
+
+    QString current = parent.path;
+    const QStringList segments = relative.split(u'/', Qt::SkipEmptyParts);
+    for (const QString &segment : segments) {
+        current = QDir(current).filePath(segment);
+        const QFileInfo info(current);
+        if ((!options.followLinks && info.isSymLink())
+            || (!excludedFolders.isEmpty()
+                && (wildcardMatch(info.fileName(), excludedFolders, cs)
+                    || wildcardMatch(QDir::cleanPath(current), excludedFolders, cs)))) {
+            return false;
+        }
+    }
+    return true;
+}
+}
+
+EffectiveRoots effectiveSearchRoots(const SearchOptions &options)
+{
+    QVector<RootCandidate> unique;
+    QSet<QString> identities;
+    int skipped = 0;
+    for (const QString &rootText : patterns(options.roots)) {
+        const QFileInfo info(rootText);
+        const QString path = QDir::cleanPath(info.absoluteFilePath());
+        const QString canonical = info.canonicalFilePath();
+        const QString identity = canonical.isEmpty()
+            ? path : QDir::cleanPath(canonical);
+        if (identities.contains(identity)) {
+            ++skipped;
+            continue;
+        }
+        identities.insert(identity);
+        unique.push_back({path});
+    }
+
+    const QStringList subfolderMasks = patterns(options.subfolderWildcards).isEmpty()
+        ? QStringList{QStringLiteral("*")} : patterns(options.subfolderWildcards);
+    const bool universalSubfolderMask =
+        subfolderMasks.contains(QStringLiteral("*"));
+    if (!options.recursive || options.maxDepth > 0 || options.maxResults > 0
+        || !universalSubfolderMask) {
+        EffectiveRoots result;
+        result.skipped = skipped;
+        for (const RootCandidate &root : unique) {
+            result.paths.push_back(root.path);
+            result.priorityPaths.push_back(root.path);
+        }
+        return result;
+    }
+
+    const Qt::CaseSensitivity cs =
+        options.caseSensitive ? Qt::CaseSensitive : Qt::CaseInsensitive;
+    const QStringList excludedFolders = patterns(options.excludeFolders);
+    EffectiveRoots result;
+    result.skipped = skipped;
+    for (const RootCandidate &root : unique)
+        result.priorityPaths.push_back(root.path);
+    for (qsizetype childIndex = 0; childIndex < unique.size(); ++childIndex) {
+        bool redundant = false;
+        for (qsizetype parentIndex = 0; parentIndex < unique.size(); ++parentIndex) {
+            if (parentIndex == childIndex)
+                continue;
+            if (canCollapseInto(unique[parentIndex], unique[childIndex], options,
+                                excludedFolders, cs)) {
+                redundant = true;
+                break;
+            }
+        }
+        if (redundant) {
+            ++result.skipped;
+        } else {
+            result.paths.push_back(unique[childIndex].path);
+        }
+    }
+    return result;
+}
+
+int preferredRootIndex(const QString &path, const QStringList &roots)
+{
+    const QString normalizedPath = QDir::cleanPath(QFileInfo(path).absoluteFilePath());
+    int bestIndex = -1;
+    qsizetype bestLength = 0;
+    for (qsizetype index = 0; index < roots.size(); ++index) {
+        const QString root = QDir::cleanPath(QFileInfo(roots[index]).absoluteFilePath());
+        if (normalizedPath != root && !isDescendantPath(root, normalizedPath))
+            continue;
+        if (root.size() > bestLength) {
+            bestIndex = int(index);
+            bestLength = root.size();
+        }
+    }
+    return bestIndex;
+}
+
 bool shouldShowDuplicateResult(bool copiesOnly, int keeperPriority)
 {
     if (keeperPriority < 1)
@@ -99,6 +227,26 @@ bool isCancelled(const std::atomic_bool *cancelled)
 {
     return cancelled && cancelled->load(std::memory_order_relaxed);
 }
+
+qint64 modifiedNanoseconds(const struct stat &st)
+{
+    return qint64(st.st_mtim.tv_sec) * 1'000'000'000LL + st.st_mtim.tv_nsec;
+}
+
+bool signatureMatches(const FileRecord &record, const struct stat &st)
+{
+    return record.size == st.st_size
+        && record.modifiedNs == modifiedNanoseconds(st)
+        && record.device == quint64(st.st_dev)
+        && record.inode == quint64(st.st_ino);
+}
+
+bool statMatches(const FileRecord &record)
+{
+    struct stat st {};
+    const QByteArray nativePath = QFile::encodeName(record.path);
+    return ::stat(nativePath.constData(), &st) == 0 && signatureMatches(record, st);
+}
 }
 
 bool fileContains(const QString &path, const SearchOptions &options,
@@ -187,6 +335,46 @@ QByteArray sha256(const QString &path, const std::atomic_bool *cancelled)
     return isCancelled(cancelled) ? QByteArray{} : hash.result();
 }
 
+bool fileSignatureMatches(const FileRecord &record)
+{
+    return statMatches(record);
+}
+
+QByteArray sha256(const FileRecord &record, const std::atomic_bool *cancelled)
+{
+    if (isCancelled(cancelled) || !statMatches(record))
+        return {};
+    const QByteArray digest = sha256(record.path, cancelled);
+    return !digest.isEmpty() && statMatches(record) ? digest : QByteArray{};
+}
+
+QByteArray sampleSha256(const FileRecord &record, const std::atomic_bool *cancelled)
+{
+    if (isCancelled(cancelled) || record.size <= duplicateSampleThreshold
+        || !statMatches(record))
+        return {};
+
+    QFile file(record.path);
+    if (!file.open(QIODevice::ReadOnly))
+        return {};
+
+    const qint64 middleOffset = (record.size - duplicateSampleBlockSize) / 2;
+    const std::array<qint64, 3> offsets{
+        0, middleOffset, record.size - duplicateSampleBlockSize
+    };
+    QCryptographicHash hash(QCryptographicHash::Sha256);
+    for (const qint64 offset : offsets) {
+        if (isCancelled(cancelled) || !file.seek(offset))
+            return {};
+        const QByteArray block = file.read(duplicateSampleBlockSize);
+        if (block.size() != duplicateSampleBlockSize)
+            return {};
+        hash.addData(block);
+    }
+    const QByteArray digest = hash.result();
+    return !isCancelled(cancelled) && statMatches(record) ? digest : QByteArray{};
+}
+
 bool parseOptionalIsoDate(const QString &text, qint64 &seconds)
 {
     const QString trimmed = text.trimmed();

src/search_core.h

@@ -11,6 +11,9 @@
 #include <optional>
 #include <sys/types.h>
 
+inline constexpr qint64 duplicateSampleBlockSize = 64LL * 1024;
+inline constexpr qint64 duplicateSampleThreshold = 4LL * 1024 * 1024;
+
 struct SearchOptions {
     QString roots = QDir::homePath();
     QString fileWildcards = QStringLiteral("*");
@@ -41,6 +44,7 @@ struct SearchOptions {
     QString mode = QStringLiteral("Standard search");
     QString duplicateNameMode = QStringLiteral("All files and folders");
     bool duplicateNameWithoutExtension = false;
+    bool strictDuplicateComparison = false;
     bool showDuplicateCopiesOnly = true;
     bool includeSubfoldersInSummary = false;
     QString hidden = QStringLiteral("Any");
@@ -60,6 +64,9 @@ struct FileRecord {
     qint64 created = 0;
     qint64 accessed = 0;
     qint64 changed = 0;
+    qint64 modifiedNs = 0;
+    quint64 device = 0;
+    quint64 inode = 0;
     QString type;
     QString owner;
     QString attributes;
@@ -67,6 +74,12 @@ struct FileRecord {
     int duplicateCopy = 0;
 };
 
+struct EffectiveRoots {
+    QStringList paths;
+    QStringList priorityPaths;
+    int skipped = 0;
+};
+
 Q_DECLARE_METATYPE(SearchOptions)
 Q_DECLARE_METATYPE(FileRecord)
 Q_DECLARE_METATYPE(QVector<FileRecord>)
@@ -74,6 +87,8 @@ Q_DECLARE_METATYPE(QVector<FileRecord>)
 QStringList patterns(const QString &text);
 QStringList exclusionPatterns(const QString &text);
 bool wildcardMatch(const QString &value, const QStringList &items, Qt::CaseSensitivity cs);
+EffectiveRoots effectiveSearchRoots(const SearchOptions &options);
+int preferredRootIndex(const QString &path, const QStringList &roots);
 QString humanSize(qint64 bytes);
 QString ownerName(uid_t uid);
 std::optional<QByteArray> hexNeedle(QString text);
@@ -82,5 +97,9 @@ bool fileContains(const QString &path, const SearchOptions &options,
 bool filesEqual(const QString &leftPath, const QString &rightPath,
                 const std::atomic_bool *cancelled = nullptr);
 QByteArray sha256(const QString &path, const std::atomic_bool *cancelled = nullptr);
+QByteArray sha256(const FileRecord &record, const std::atomic_bool *cancelled = nullptr);
+QByteArray sampleSha256(const FileRecord &record,
+                        const std::atomic_bool *cancelled = nullptr);
+bool fileSignatureMatches(const FileRecord &record);
 bool parseOptionalIsoDate(const QString &text, qint64 &seconds);
 bool shouldShowDuplicateResult(bool copiesOnly, int keeperPriority);

src/search_engine.cpp

@@ -0,0 +1,596 @@
+#include "search_engine.h"
+
+#include <QCryptographicHash>
+#include <QDataStream>
+#include <QDateTime>
+#include <QDir>
+#include <QFileInfo>
+#include <QThread>
+#include <QThreadPool>
+#include <QtConcurrent>
+
+#include <algorithm>
+#include <filesystem>
+#include <functional>
+#include <sys/stat.h>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+namespace fs = std::filesystem;
+
+namespace {
+struct HashedRecord {
+    QByteArray digest;
+    FileRecord record;
+};
+
+bool keepFirst(const FileRecord &left, const FileRecord &right,
+               const QStringList &priorityRoots)
+{
+    const int leftRoot = preferredRootIndex(left.path, priorityRoots);
+    const int rightRoot = preferredRootIndex(right.path, priorityRoots);
+    const int leftPriority = leftRoot < 0 ? priorityRoots.size() : leftRoot;
+    const int rightPriority = rightRoot < 0 ? priorityRoots.size() : rightRoot;
+    if (leftPriority != rightPriority)
+        return leftPriority < rightPriority;
+    if (left.modified != right.modified)
+        return left.modified > right.modified;
+    return left.path < right.path;
+}
+}
+
+void SearchEngine::search(const SearchOptions &o)
+{
+    cancelled_.store(false, std::memory_order_relaxed);
+    const auto finishIfCancelled = [this] {
+        if (!cancelled_.load(std::memory_order_relaxed))
+            return false;
+        emit finished({}, tr("Search stopped"));
+        return true;
+    };
+    cancelledByLimit_ = false;
+    cache_.setEnabled(o.useCache);
+    cacheHits_.store(0, std::memory_order_relaxed);
+    cacheMisses_.store(0, std::memory_order_relaxed);
+    const auto started = std::chrono::steady_clock::now();
+    QVector<FileRecord> candidates;
+    QSet<QString> candidatePaths;
+    const EffectiveRoots roots = effectiveSearchRoots(o);
+    const Qt::CaseSensitivity cs = o.caseSensitive ? Qt::CaseSensitive : Qt::CaseInsensitive;
+    const QStringList fileMasks = patterns(o.fileWildcards).isEmpty()
+        ? QStringList{QStringLiteral("*")} : patterns(o.fileWildcards);
+    const QStringList subfolderMasks = patterns(o.subfolderWildcards).isEmpty()
+        ? QStringList{QStringLiteral("*")} : patterns(o.subfolderWildcards);
+    const QStringList excludedFiles = exclusionPatterns(o.excludeFiles);
+    const QStringList excludedFolders = patterns(o.excludeFolders);
+    const QStringList includedFolders = patterns(o.includeFolders);
+    quint64 scanned = 0;
+    quint64 totalEntries = 0;
+
+    if (o.accurateProgress) {
+        emit phaseProgress(tr("Counting files"), 0, 0);
+        for (const QString &rootText : roots.paths) {
+            if (cancelled_.load(std::memory_order_relaxed))
+                break;
+            std::error_code ec;
+            const fs::path root = fs::path(rootText.toStdString());
+            fs::directory_options dirOptions = fs::directory_options::skip_permission_denied;
+            if (o.followLinks)
+                dirOptions |= fs::directory_options::follow_directory_symlink;
+            if (!o.recursive) {
+                for (fs::directory_iterator it(root, dirOptions, ec), end;
+                     it != end && !ec && !cancelled_.load(std::memory_order_relaxed);
+                     it.increment(ec)) {
+                    ++totalEntries;
+                    if (totalEntries % 2048 == 0)
+                        emit phaseProgress(tr("Counting files"), totalEntries, 0);
+                }
+                continue;
+            }
+            for (fs::recursive_directory_iterator it(root, dirOptions, ec), end;
+                 it != end && !ec && !cancelled_.load(std::memory_order_relaxed); it.increment(ec)) {
+                if (it->is_directory(ec)) {
+                    const QString name = QString::fromStdString(it->path().filename().string());
+                    const QString fullPath = QString::fromStdString(it->path().string());
+                    if ((!excludedFolders.isEmpty()
+                         && (wildcardMatch(name, excludedFolders, cs)
+                             || wildcardMatch(fullPath, excludedFolders, cs)))
+                        || (o.maxDepth > 0 && it.depth() >= o.maxDepth - 1)) {
+                        it.disable_recursion_pending();
+                    }
+                }
+                ++totalEntries;
+                if (totalEntries % 2048 == 0)
+                    emit phaseProgress(tr("Counting files"), totalEntries, 0);
+            }
+        }
+        emit phaseProgress(tr("Scanning files"), 0, totalEntries);
+    }
+
+    for (const QString &rootText : roots.paths) {
+        if (cancelled_.load(std::memory_order_relaxed))
+            break;
+        std::error_code ec;
+        fs::path root = fs::path(rootText.toStdString());
+        fs::directory_options dirOptions = fs::directory_options::skip_permission_denied;
+        if (o.followLinks)
+            dirOptions |= fs::directory_options::follow_directory_symlink;
+
+        auto process = [&](const fs::directory_entry &entry, const fs::path &baseRoot) {
+            if (cancelled_.load(std::memory_order_relaxed))
+                return;
+            const QString path = QDir::cleanPath(QFileInfo(
+                QString::fromStdString(entry.path().string())).absoluteFilePath());
+            const QString name = QString::fromStdString(entry.path().filename().string());
+            const bool isDir = entry.is_directory(ec);
+            if ((isDir && !o.findFolders) || (!isDir && !o.findFiles))
+                return;
+            const fs::path parentPath = entry.path().parent_path();
+            const bool isBaseFolder = parentPath == baseRoot;
+            const QString parentName = QString::fromStdString(parentPath.filename().string());
+            if (!isBaseFolder && !wildcardMatch(parentName, subfolderMasks, cs))
+                return;
+            if (!wildcardMatch(name, fileMasks, cs))
+                return;
+            if (!excludedFiles.isEmpty() && wildcardMatch(name, excludedFiles, cs))
+                return;
+            if (!includedFolders.isEmpty()) {
+                const QString folderPath = isDir ? path : QFileInfo(path).absolutePath();
+                const QString folderName = isDir ? name : QFileInfo(path).dir().dirName();
+                if (!wildcardMatch(folderPath, includedFolders, cs)
+                    && !wildcardMatch(folderName, includedFolders, cs))
+                    return;
+            }
+
+            struct stat st {};
+            const QByteArray nativePath = QFile::encodeName(path);
+            if (::stat(nativePath.constData(), &st) != 0)
+                return;
+            const qint64 size = isDir ? 0 : st.st_size;
+            if (o.minSize > 0 && size < o.minSize)
+                return;
+            if (o.maxSize > 0 && size > o.maxSize)
+                return;
+            const qint64 selectedTime = o.timeField == QStringLiteral("Accessed time")
+                ? st.st_atime
+                : o.timeField == QStringLiteral("Metadata changed time") ? st.st_ctime : st.st_mtime;
+            const qint64 now = QDateTime::currentSecsSinceEpoch();
+            if (o.lastMinutes > 0 && selectedTime < now - qint64(o.lastMinutes) * 60)
+                return;
+            if (o.minTime > 0 && selectedTime < o.minTime)
+                return;
+            if (o.maxTime > 0 && selectedTime > o.maxTime)
+                return;
+            const bool hidden = name.startsWith(u'.');
+            const bool readOnly = !(st.st_mode & S_IWUSR);
+            const bool executable = st.st_mode & S_IXUSR;
+            const auto attrMatches = [](const QString &wanted, bool actual) {
+                return wanted == QStringLiteral("Any") || (wanted == QStringLiteral("Yes")) == actual;
+            };
+            if (!attrMatches(o.hidden, hidden)
+                || !attrMatches(o.readonly, readOnly)
+                || !attrMatches(o.executable, executable))
+                return;
+            if (candidatePaths.contains(path))
+                return;
+            candidatePaths.insert(path);
+
+            QString attrs;
+            attrs += isDir ? u'd' : u'-';
+            attrs += hidden ? u'h' : u'-';
+            attrs += readOnly ? u'r' : u'-';
+            attrs += executable ? u'x' : u'-';
+            attrs += entry.is_symlink(ec) ? u'l' : u'-';
+            candidates.push_back({
+                path, name, QFileInfo(path).absolutePath(), size,
+                isDir ? 0 : qint64(st.st_blocks) * 512,
+                st.st_mtime,
+                QFileInfo(path).birthTime().isValid() ? QFileInfo(path).birthTime().toSecsSinceEpoch() : 0,
+                st.st_atime, st.st_ctime,
+                qint64(st.st_mtim.tv_sec) * 1'000'000'000LL + st.st_mtim.tv_nsec,
+                quint64(st.st_dev), quint64(st.st_ino),
+                isDir ? QStringLiteral("Folder") : QStringLiteral("File"),
+                o.retrieveOwner ? ownerName(st.st_uid) : QString{}, attrs, 0, 0
+            });
+            if (o.maxResults > 0 && o.contains.isEmpty() && candidates.size() >= o.maxResults)
+                cancelledByLimit_ = true;
+        };
+
+        if (!o.recursive) {
+            for (fs::directory_iterator it(root, dirOptions, ec), end;
+                 it != end && !ec && !cancelled_.load(std::memory_order_relaxed)
+                     && !cancelledByLimit_;
+                 it.increment(ec)) {
+                process(*it, root);
+                if (++scanned % 512 == 0) {
+                    if (totalEntries)
+                        emit phaseProgress(tr("Scanning files"), scanned, totalEntries);
+                    else
+                        emit progress(QString::fromStdString(it->path().string()), scanned);
+                }
+            }
+            continue;
+        }
+
+        for (fs::recursive_directory_iterator it(root, dirOptions, ec), end;
+             it != end && !ec && !cancelled_.load(std::memory_order_relaxed)
+                 && !cancelledByLimit_; it.increment(ec)) {
+            const QString name = QString::fromStdString(it->path().filename().string());
+            if (it->is_directory(ec)) {
+                const QString fullPath = QString::fromStdString(it->path().string());
+                if (!excludedFolders.isEmpty()
+                    && (wildcardMatch(name, excludedFolders, cs)
+                        || wildcardMatch(fullPath, excludedFolders, cs))) {
+                    it.disable_recursion_pending();
+                }
+                if (o.maxDepth > 0 && it.depth() >= o.maxDepth - 1)
+                    it.disable_recursion_pending();
+            }
+            process(*it, root);
+            if (++scanned % 512 == 0) {
+                if (totalEntries)
+                    emit phaseProgress(tr("Scanning files"), scanned, totalEntries);
+                else
+                    emit progress(QString::fromStdString(it->path().string()), scanned);
+            }
+        }
+        if (cancelledByLimit_)
+            break;
+    }
+
+    if (totalEntries)
+        emit phaseProgress(tr("Scanning files"), std::min(scanned, totalEntries), totalEntries);
+
+    if (finishIfCancelled())
+        return;
+
+    if (!o.contains.isEmpty() && !o.findFolders) {
+        emit phaseProgress(tr("Searching file contents"), 0, candidates.size());
+        std::atomic<qsizetype> checked = 0;
+        const qsizetype total = candidates.size();
+        QFuture<FileRecord> future = QtConcurrent::filtered(
+            candidates, [this, o, &checked, total](const FileRecord &r) {
+                if (cancelled_.load(std::memory_order_relaxed))
+                    return false;
+                const bool matched = cachedFileContains(r, o);
+                const qsizetype done = checked.fetch_add(1, std::memory_order_relaxed) + 1;
+                if (done == total || done % 32 == 0)
+                    emit phaseProgress(tr("Searching file contents"), done, total);
+                return matched;
+            });
+        future.waitForFinished();
+        if (finishIfCancelled())
+            return;
+        candidates = future.results();
+        if (o.maxResults > 0 && candidates.size() > o.maxResults)
+            candidates.resize(o.maxResults);
+    }
+
+    QThreadPool hashPool;
+    const int idealThreads = QThread::idealThreadCount();
+    hashPool.setMaxThreadCount(std::clamp(
+        idealThreads > 0 ? idealThreads / 2 : 1, 1, 4));
+
+    QVector<FileRecord> results;
+    if (o.mode == QStringLiteral("Duplicates search")
+        || o.mode == QStringLiteral("Non-Duplicates search")) {
+        std::unordered_map<qint64, QVector<FileRecord>> bySize;
+        QSet<QString> duplicateInputPaths;
+        for (const auto &record : candidates) {
+            if (record.type == QStringLiteral("File")
+                && !duplicateInputPaths.contains(record.path)) {
+                duplicateInputPaths.insert(record.path);
+                bySize[record.size].push_back(record);
+            }
+        }
+
+        QVector<FileRecord> sampleCandidates;
+        QVector<FileRecord> fullHashCandidates;
+        for (const auto &[size, records] : bySize) {
+            if (records.size() < 2)
+                continue;
+            if (size > duplicateSampleThreshold)
+                sampleCandidates += records;
+            else
+                fullHashCandidates += records;
+        }
+
+        std::atomic<qsizetype> sampled = 0;
+        const qsizetype sampleTotal = sampleCandidates.size();
+        if (sampleTotal)
+            emit phaseProgress(tr("Sampling duplicate candidates"), 0, sampleTotal);
+        const auto samples = QtConcurrent::blockingMapped(
+            &hashPool, sampleCandidates,
+            [this, &sampled, sampleTotal](const FileRecord &record) {
+                HashedRecord result{cachedSampleSha256(record), record};
+                const qsizetype done = sampled.fetch_add(1, std::memory_order_relaxed) + 1;
+                if (done == sampleTotal || done % 16 == 0)
+                    emit phaseProgress(tr("Sampling duplicate candidates"), done, sampleTotal);
+                return result;
+            });
+        if (finishIfCancelled())
+            return;
+
+        QHash<qint64, QHash<QByteArray, QVector<FileRecord>>> bySample;
+        for (const auto &sample : samples)
+            if (!sample.digest.isEmpty())
+                bySample[sample.record.size][sample.digest].push_back(sample.record);
+        for (const auto &sameSize : bySample)
+            for (const auto &sameSample : sameSize)
+                if (sameSample.size() > 1)
+                    fullHashCandidates += sameSample;
+
+        std::atomic<qsizetype> hashed = 0;
+        const qsizetype hashTotal = fullHashCandidates.size();
+        if (hashTotal)
+            emit phaseProgress(tr("Hashing duplicate candidates"), 0, hashTotal);
+        const auto hashes = QtConcurrent::blockingMapped(
+            &hashPool, fullHashCandidates,
+            [this, &hashed, hashTotal](const FileRecord &record) {
+                HashedRecord result{cachedSha256(record), record};
+                const qsizetype done = hashed.fetch_add(1, std::memory_order_relaxed) + 1;
+                if (done == hashTotal || done % 16 == 0)
+                    emit phaseProgress(tr("Hashing duplicate candidates"), done, hashTotal);
+                return result;
+            });
+        if (finishIfCancelled())
+            return;
+
+        QHash<qint64, QHash<QByteArray, QVector<FileRecord>>> byHash;
+        for (const auto &hash : hashes)
+            if (!hash.digest.isEmpty())
+                byHash[hash.record.size][hash.digest].push_back(hash.record);
+
+        int group = 1;
+        QSet<QString> duplicatedPaths;
+        for (const auto &sameSize : byHash) {
+            for (const auto &hashCandidates : sameSize) {
+                if (cancelled_.load(std::memory_order_relaxed))
+                    break;
+                if (hashCandidates.size() < 2)
+                    continue;
+                QVector<QVector<FileRecord>> exactGroups;
+                if (!o.strictDuplicateComparison) {
+                    exactGroups.push_back(hashCandidates);
+                } else {
+                    for (const auto &record : hashCandidates) {
+                        if (cancelled_.load(std::memory_order_relaxed))
+                            break;
+                        bool placed = false;
+                        for (auto &exact : exactGroups) {
+                            if (fileSignatureMatches(exact.front())
+                                && fileSignatureMatches(record)
+                                && filesEqual(exact.front().path, record.path, &cancelled_)
+                                && fileSignatureMatches(exact.front())
+                                && fileSignatureMatches(record)) {
+                                exact.push_back(record);
+                                placed = true;
+                                break;
+                            }
+                        }
+                        if (!placed)
+                            exactGroups.push_back({record});
+                    }
+                }
+                for (auto &exact : exactGroups) {
+                    if (cancelled_.load(std::memory_order_relaxed))
+                        break;
+                    if (exact.size() < 2)
+                        continue;
+                    std::stable_sort(exact.begin(), exact.end(),
+                                     [&roots](const FileRecord &left,
+                                              const FileRecord &right) {
+                        return keepFirst(left, right, roots.priorityPaths);
+                    });
+                    int duplicateCopy = 1;
+                    for (auto &record : exact) {
+                        record.group = group;
+                        record.duplicateCopy = duplicateCopy++;
+                        duplicatedPaths.insert(record.path);
+                        if (o.mode == QStringLiteral("Duplicates search")
+                            && shouldShowDuplicateResult(
+                                o.showDuplicateCopiesOnly, record.duplicateCopy)) {
+                            results.push_back(record);
+                        }
+                    }
+                    ++group;
+                }
+            }
+        }
+        if (finishIfCancelled())
+            return;
+        if (o.mode == QStringLiteral("Non-Duplicates search")) {
+            for (const auto &record : candidates)
+                if (record.type == QStringLiteral("File") && !duplicatedPaths.contains(record.path))
+                    results.push_back(record);
+        }
+    } else if (o.mode == QStringLiteral("Duplicate names search")) {
+        QHash<QString, QVector<FileRecord>> byName;
+        for (const auto &record : candidates) {
+            const QString key = o.duplicateNameWithoutExtension
+                ? QFileInfo(record.name).completeBaseName().toCaseFolded()
+                : record.name.toCaseFolded();
+            byName[key].push_back(record);
+        }
+        int group = 1;
+        quint64 namesDone = 0;
+        emit phaseProgress(tr("Comparing duplicate names"), 0, byName.size());
+        for (auto sameName : byName) {
+            if (cancelled_.load(std::memory_order_relaxed))
+                break;
+            ++namesDone;
+            if (namesDone % 32 == 0 || namesDone == quint64(byName.size()))
+                emit phaseProgress(tr("Comparing duplicate names"), namesDone, byName.size());
+            if (o.duplicateNameMode != QStringLiteral("All files and folders"))
+                sameName.erase(std::remove_if(sameName.begin(), sameName.end(),
+                    [](const FileRecord &r) { return r.type != QStringLiteral("File"); }), sameName.end());
+            if (sameName.size() < 2)
+                continue;
+            std::stable_sort(sameName.begin(), sameName.end(),
+                             [&roots](const FileRecord &left,
+                                      const FileRecord &right) {
+                return keepFirst(left, right, roots.priorityPaths);
+            });
+            if (o.duplicateNameMode.contains(QStringLiteral("identical"), Qt::CaseInsensitive)) {
+                bool identical = std::all_of(
+                    sameName.cbegin(), sameName.cend(),
+                    [&sameName](const FileRecord &record) {
+                        return record.size == sameName.front().size;
+                    });
+                if (identical && sameName.front().size > duplicateSampleThreshold) {
+                    const auto samples = QtConcurrent::blockingMapped(
+                        &hashPool, sameName, [this](const FileRecord &record) {
+                            return cachedSampleSha256(record);
+                        });
+                    identical = !samples.isEmpty() && !samples.front().isEmpty()
+                        && std::all_of(samples.cbegin(), samples.cend(),
+                            [&samples](const QByteArray &digest) {
+                                return digest == samples.front();
+                            });
+                }
+                QVector<QByteArray> hashes;
+                if (identical) {
+                    hashes = QtConcurrent::blockingMapped(
+                        &hashPool, sameName, [this](const FileRecord &record) {
+                            return cachedSha256(record);
+                        });
+                    identical = !hashes.isEmpty() && !hashes.front().isEmpty()
+                        && std::all_of(hashes.cbegin(), hashes.cend(),
+                            [&hashes](const QByteArray &digest) {
+                                return digest == hashes.front();
+                            });
+                }
+                if (identical && o.strictDuplicateComparison) {
+                    const FileRecord &first = sameName.front();
+                    for (qsizetype index = 1; identical && index < sameName.size(); ++index) {
+                        const FileRecord &record = sameName[index];
+                        identical = fileSignatureMatches(first)
+                            && fileSignatureMatches(record)
+                            && filesEqual(first.path, record.path, &cancelled_)
+                            && fileSignatureMatches(first)
+                            && fileSignatureMatches(record);
+                    }
+                }
+                const bool wantsNonIdentical = o.duplicateNameMode.startsWith(QStringLiteral("Only non"));
+                if (identical == wantsNonIdentical)
+                    continue;
+            }
+            int duplicateCopy = 1;
+            for (auto &record : sameName) {
+                record.group = group;
+                record.duplicateCopy = duplicateCopy++;
+                results.push_back(record);
+            }
+            ++group;
+        }
+        if (finishIfCancelled())
+            return;
+    } else if (o.mode == QStringLiteral("Summary")) {
+        QHash<QString, QVector<FileRecord>> byFolder;
+        for (const auto &record : candidates) {
+            if (cancelled_.load(std::memory_order_relaxed))
+                break;
+            byFolder[record.folder].push_back(record);
+            if (o.includeSubfoldersInSummary) {
+                QDir parent(record.folder);
+                while (parent.cdUp()) {
+                    const QString ancestor = parent.absolutePath();
+                    bool belongsToRoot = false;
+                    for (const QString &root : roots.paths) {
+                        if (ancestor == QDir(root).absolutePath()) {
+                            belongsToRoot = true;
+                            break;
+                        }
+                    }
+                    byFolder[ancestor].push_back(record);
+                    if (belongsToRoot)
+                        break;
+                }
+            }
+        }
+        for (auto it = byFolder.cbegin(); it != byFolder.cend(); ++it) {
+            if (cancelled_.load(std::memory_order_relaxed))
+                break;
+            qint64 total = 0;
+            qint64 totalOnDisk = 0;
+            qint64 newest = 0;
+            for (const auto &record : it.value()) {
+                total += record.size;
+                totalOnDisk += record.sizeOnDisk;
+                newest = std::max(newest, record.modified);
+            }
+            const QFileInfo info(it.key());
+            results.push_back({it.key(), info.fileName(), info.absolutePath(), total, totalOnDisk,
+                               newest, 0, 0, 0, 0, 0, 0,
+                               tr("%1 files").arg(it.value().size()), {}, {}, 0, 0});
+        }
+        if (finishIfCancelled())
+            return;
+    } else {
+        results = std::move(candidates);
+    }
+
+    if (finishIfCancelled())
+        return;
+    const double seconds = std::chrono::duration<double>(
+        std::chrono::steady_clock::now() - started).count();
+    cache_.save();
+    QString message = tr("%1 results, %2 entries scanned in %3 seconds; cache: %4 hits")
+                          .arg(results.size()).arg(scanned).arg(seconds, 0, 'f', 2)
+                          .arg(cacheHits_.load(std::memory_order_relaxed));
+    if (roots.skipped > 0)
+        message += tr("; %1 redundant roots skipped").arg(roots.skipped);
+    emit finished(results, message);
+}
+
+QByteArray SearchEngine::cachedSampleSha256(const FileRecord &record)
+{
+    QByteArray digest;
+    if (cache_.findSampleHash(record, digest)) {
+        if (!fileSignatureMatches(record))
+            return {};
+        cacheHits_.fetch_add(1, std::memory_order_relaxed);
+        return digest;
+    }
+    cacheMisses_.fetch_add(1, std::memory_order_relaxed);
+    digest = sampleSha256(record, &cancelled_);
+    if (!digest.isEmpty() && !cancelled_.load(std::memory_order_relaxed))
+        cache_.storeSampleHash(record, digest);
+    return digest;
+}
+
+QByteArray SearchEngine::cachedSha256(const FileRecord &record)
+{
+    QByteArray digest;
+    if (cache_.findHash(record, digest)) {
+        if (!fileSignatureMatches(record))
+            return {};
+        cacheHits_.fetch_add(1, std::memory_order_relaxed);
+        return digest;
+    }
+    cacheMisses_.fetch_add(1, std::memory_order_relaxed);
+    digest = sha256(record, &cancelled_);
+    if (!digest.isEmpty() && !cancelled_.load(std::memory_order_relaxed))
+        cache_.storeHash(record, digest);
+    return digest;
+}
+
+bool SearchEngine::cachedFileContains(const FileRecord &record, const SearchOptions &o)
+{
+    QByteArray queryData;
+    QDataStream stream(&queryData, QIODevice::WriteOnly);
+    stream << o.contains << o.binary << o.multipleValues << o.multipleAnd << o.caseSensitive;
+    const QByteArray queryKey = QCryptographicHash::hash(queryData, QCryptographicHash::Sha256);
+    if (const auto cached = cache_.findContent(record, queryKey)) {
+        if (!fileSignatureMatches(record))
+            return false;
+        cacheHits_.fetch_add(1, std::memory_order_relaxed);
+        return *cached;
+    }
+    cacheMisses_.fetch_add(1, std::memory_order_relaxed);
+    const bool matched = fileContains(record.path, o, &cancelled_);
+    if (!cancelled_.load(std::memory_order_relaxed))
+        cache_.storeContent(record, queryKey, matched);
+    return matched;
+}

src/search_engine.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <QObject>
+#include <QVector>
+#include <QString>
+
+#include <atomic>
+#include <chrono>
+#include <utility>
+
+#include "search_core.h"
+#include "search_cache.h"
+
+class SearchEngine final : public QObject {
+    Q_OBJECT
+public:
+    explicit SearchEngine(QObject *parent = nullptr, QString cachePath = {})
+        : QObject(parent), cache_(std::move(cachePath)) {}
+
+public slots:
+    void stop() { cancelled_.store(true, std::memory_order_relaxed); }
+    void clearCache()
+    {
+        cache_.clear();
+        emit cacheCleared();
+    }
+
+    void search(const SearchOptions &o);
+
+signals:
+    void progress(const QString &path, quint64 scanned);
+    void phaseProgress(const QString &phase, quint64 completed, quint64 total);
+    void cacheCleared();
+    void finished(const QVector<FileRecord> &results, const QString &message);
+
+private:
+    QByteArray cachedSampleSha256(const FileRecord &record);
+    QByteArray cachedSha256(const FileRecord &record);
+    bool cachedFileContains(const FileRecord &record, const SearchOptions &o);
+
+    SearchCache cache_;
+    std::atomic<quint64> cacheHits_ = 0;
+    std::atomic<quint64> cacheMisses_ = 0;
+    std::atomic_bool cancelled_ = false;
+    bool cancelledByLimit_ = false;
+};

tests/options_dialog_test.cpp

@@ -0,0 +1,61 @@
+#include "options_dialog.h"
+
+#include <QCheckBox>
+#include <QComboBox>
+#include <QSettings>
+#include <QtTest>
+
+class OptionsDialogTest final : public QObject {
+    Q_OBJECT
+
+private slots:
+    void exposesStrictDuplicateComparison()
+    {
+        SearchOptions options;
+        QVERIFY(!options.strictDuplicateComparison);
+        options.strictDuplicateComparison = true;
+
+        OptionsDialog dialog(options);
+        auto *strict = dialog.findChild<QCheckBox *>(
+            QStringLiteral("strictDuplicateComparison"));
+        QVERIFY(strict);
+        QVERIFY(strict->isChecked());
+        QVERIFY(dialog.options().strictDuplicateComparison);
+
+        strict->setChecked(false);
+        QVERIFY(!dialog.options().strictDuplicateComparison);
+    }
+
+    void remembersInputHistory()
+    {
+        QSettings settings;
+        settings.remove(QStringLiteral("inputHistory"));
+
+        SearchOptions options;
+        OptionsDialog first(options);
+        auto *roots = first.findChild<QComboBox *>(QStringLiteral("historyroots"));
+        QVERIFY(roots);
+        roots->setEditText(QStringLiteral("/tmp/first;/tmp/second"));
+        QVERIFY(QMetaObject::invokeMethod(&first, "accept"));
+
+        QCOMPARE(settings.value(QStringLiteral("inputHistory/roots")).toStringList(),
+                 QStringList{QStringLiteral("/tmp/first;/tmp/second")});
+
+        OptionsDialog second(options);
+        auto *history = second.findChild<QComboBox *>(QStringLiteral("historyroots"));
+        QVERIFY(history);
+        QCOMPARE(history->itemText(0), QStringLiteral("/tmp/first;/tmp/second"));
+
+        history->setEditText(QStringLiteral("/tmp/new"));
+        QVERIFY(QMetaObject::invokeMethod(&second, "accept"));
+        QCOMPARE(settings.value(QStringLiteral("inputHistory/roots")).toStringList(),
+                 (QStringList{QStringLiteral("/tmp/new"),
+                              QStringLiteral("/tmp/first;/tmp/second")}));
+
+        settings.remove(QStringLiteral("inputHistory"));
+    }
+};
+
+QTEST_MAIN(OptionsDialogTest)
+
+#include "options_dialog_test.moc"

tests/search_cache_test.cpp

@@ -0,0 +1,112 @@
+#include "search_cache.h"
+
+#include <QDataStream>
+#include <QFile>
+#include <QTemporaryDir>
+#include <QtTest>
+
+class SearchCacheTest final : public QObject {
+    Q_OBJECT
+
+private:
+    static FileRecord record()
+    {
+        FileRecord value;
+        value.path = QStringLiteral("/tmp/cache-test.bin");
+        value.size = 1234;
+        value.modifiedNs = 5678;
+        value.device = 9;
+        value.inode = 10;
+        return value;
+    }
+
+private slots:
+    void storesAndReloadsBothHashes()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        const QString path = directory.filePath(QStringLiteral("cache.dat"));
+        const FileRecord value = record();
+        const QByteArray sample("sample");
+        const QByteArray full("full");
+        const QByteArray query("query");
+
+        {
+            SearchCache cache(path);
+            cache.storeSampleHash(value, sample);
+            cache.storeHash(value, full);
+            cache.storeContent(value, query, true);
+            cache.save();
+        }
+
+        SearchCache cache(path);
+        QByteArray digest;
+        QVERIFY(cache.findSampleHash(value, digest));
+        QCOMPARE(digest, sample);
+        QVERIFY(cache.findHash(value, digest));
+        QCOMPARE(digest, full);
+        QCOMPARE(cache.findContent(value, query), std::optional<bool>(true));
+    }
+
+    void invalidatesEverySignatureField()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        SearchCache cache(directory.filePath(QStringLiteral("cache.dat")));
+        const FileRecord value = record();
+        cache.storeSampleHash(value, QByteArray("sample"));
+        cache.storeHash(value, QByteArray("full"));
+
+        const auto misses = [&cache](FileRecord changed) {
+            QByteArray digest;
+            return !cache.findSampleHash(changed, digest)
+                && !cache.findHash(changed, digest);
+        };
+
+        FileRecord changed = value;
+        ++changed.size;
+        QVERIFY(misses(changed));
+        changed = value;
+        ++changed.modifiedNs;
+        QVERIFY(misses(changed));
+        changed = value;
+        ++changed.device;
+        QVERIFY(misses(changed));
+        changed = value;
+        ++changed.inode;
+        QVERIFY(misses(changed));
+    }
+
+    void ignoresVersionOneData()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        const QString path = directory.filePath(QStringLiteral("cache.dat"));
+        QFile file(path);
+        QVERIFY(file.open(QIODevice::WriteOnly));
+        QDataStream stream(&file);
+        stream.setVersion(QDataStream::Qt_6_0);
+        stream << quint32(0x46534348) << quint32(1) << quint32(0);
+        file.close();
+
+        SearchCache cache(path);
+        QByteArray digest;
+        QVERIFY(!cache.findHash(record(), digest));
+        cache.storeHash(record(), QByteArray("full"));
+        cache.save();
+
+        QFile saved(path);
+        QVERIFY(saved.open(QIODevice::ReadOnly));
+        QDataStream savedStream(&saved);
+        savedStream.setVersion(QDataStream::Qt_6_0);
+        quint32 magic = 0;
+        quint32 version = 0;
+        savedStream >> magic >> version;
+        QCOMPARE(magic, quint32(0x46534348));
+        QCOMPARE(version, quint32(2));
+    }
+};
+
+QTEST_GUILESS_MAIN(SearchCacheTest)
+
+#include "search_cache_test.moc"

tests/search_core_test.cpp

@@ -5,6 +5,35 @@
 #include <QTemporaryDir>
 #include <QtTest>
 
+#include <sys/stat.h>
+
+namespace {
+FileRecord recordFor(const QString &path)
+{
+    struct stat st {};
+    const QByteArray nativePath = QFile::encodeName(path);
+    if (::stat(nativePath.constData(), &st) != 0)
+        return {};
+    FileRecord record;
+    record.path = path;
+    record.size = st.st_size;
+    record.modified = st.st_mtime;
+    record.modifiedNs =
+        qint64(st.st_mtim.tv_sec) * 1'000'000'000LL + st.st_mtim.tv_nsec;
+    record.device = st.st_dev;
+    record.inode = st.st_ino;
+    record.type = QStringLiteral("File");
+    return record;
+}
+
+bool writeFile(const QString &path, const QByteArray &data)
+{
+    QFile file(path);
+    return file.open(QIODevice::WriteOnly)
+        && file.write(data) == data.size();
+}
+}
+
 class SearchCoreTest final : public QObject {
     Q_OBJECT
 
@@ -23,6 +52,113 @@ private slots:
                                Qt::CaseSensitive));
     }
 
+    void collapsesRedundantSearchRoots()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        QDir root(directory.path());
+        QVERIFY(root.mkpath(QStringLiteral("child")));
+        QVERIFY(root.mkpath(QStringLiteral("misc")));
+
+        SearchOptions options;
+        const QString child = directory.filePath(QStringLiteral("child"));
+        const QString misc = directory.filePath(QStringLiteral("misc"));
+        options.roots = QStringLiteral("%1;%2/;%1;%3")
+                            .arg(child, directory.path(), misc);
+        options.excludeFolders = QStringLiteral("unrelated");
+
+        const EffectiveRoots effective = effectiveSearchRoots(options);
+        QCOMPARE(effective.paths, QStringList({directory.path()}));
+        QCOMPARE(effective.skipped, 3);
+    }
+
+    void preservesNestedRootsThatExpandCoverage()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        QDir root(directory.path());
+        QVERIFY(root.mkpath(QStringLiteral("child")));
+        const QString child = directory.filePath(QStringLiteral("child"));
+
+        SearchOptions options;
+        options.roots = directory.path() + u';' + child;
+
+        options.recursive = false;
+        QCOMPARE(effectiveSearchRoots(options).paths.size(), 2);
+
+        options.recursive = true;
+        options.maxDepth = 1;
+        QCOMPARE(effectiveSearchRoots(options).paths.size(), 2);
+
+        options.maxDepth = 0;
+        options.maxResults = 1;
+        QCOMPARE(effectiveSearchRoots(options).paths.size(), 2);
+
+        options.maxResults = 0;
+        options.subfolderWildcards = QStringLiteral("matched-*");
+        QCOMPARE(effectiveSearchRoots(options).paths.size(), 2);
+
+        options.subfolderWildcards = QStringLiteral("*");
+        options.excludeFolders = QStringLiteral("child");
+        QCOMPARE(effectiveSearchRoots(options).paths.size(), 2);
+
+        options.excludeFolders = QStringLiteral("unrelated");
+        QCOMPARE(effectiveSearchRoots(options).paths,
+                 QStringList({directory.path()}));
+    }
+
+    void respectsSymlinksWhenCollapsingRoots()
+    {
+        QTemporaryDir directory;
+        QTemporaryDir external;
+        QVERIFY(directory.isValid());
+        QVERIFY(external.isValid());
+        QDir externalRoot(external.path());
+        QVERIFY(externalRoot.mkpath(QStringLiteral("child")));
+        const QString link = directory.filePath(QStringLiteral("link"));
+        QVERIFY(QFile::link(external.path(), link));
+        const QString linkedChild = QDir(link).filePath(QStringLiteral("child"));
+
+        SearchOptions options;
+        options.roots = directory.path() + u';' + linkedChild;
+        options.followLinks = false;
+        QCOMPARE(effectiveSearchRoots(options).paths.size(), 2);
+
+        options.followLinks = true;
+        QCOMPARE(effectiveSearchRoots(options).paths,
+                 QStringList({directory.path()}));
+
+        options.roots = external.path() + u';' + link;
+        const EffectiveRoots aliases = effectiveSearchRoots(options);
+        QCOMPARE(aliases.paths.size(), 1);
+        QCOMPARE(aliases.skipped, 1);
+    }
+
+    void prefersTheMostSpecificConfiguredRoot()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        QDir root(directory.path());
+        QVERIFY(root.mkpath(QStringLiteral("Temp")));
+        QVERIFY(root.mkpath(QStringLiteral("misc")));
+        const QString temp = directory.filePath(QStringLiteral("Temp"));
+        const QString misc = directory.filePath(QStringLiteral("misc"));
+        const QStringList roots{directory.path(), temp, misc};
+
+        QCOMPARE(preferredRootIndex(
+                     directory.filePath(QStringLiteral("base.mp4")), roots), 0);
+        QCOMPARE(preferredRootIndex(
+                     QDir(temp).filePath(QStringLiteral("copy.mp4")), roots), 1);
+        QCOMPARE(preferredRootIndex(
+                     QDir(misc).filePath(QStringLiteral("copy.mp4")), roots), 2);
+        QCOMPARE(preferredRootIndex(
+                     directory.filePath(QStringLiteral("unrelated/file.mp4")), roots), 0);
+
+        const QStringList similarRoots{directory.filePath(QStringLiteral("foo"))};
+        QCOMPARE(preferredRootIndex(
+                     directory.filePath(QStringLiteral("foobar/file.mp4")), similarRoots), -1);
+    }
+
     void parsesOptionalIsoDates()
     {
         qint64 seconds = -1;
@@ -108,6 +244,72 @@ private slots:
         QVERIFY(!filesEqual(path, path, &cancelled));
         QVERIFY(sha256(path, &cancelled).isEmpty());
     }
+
+    void samplesLargeFilesAndValidatesSignatures()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        const QByteArray content(duplicateSampleThreshold + 1024 * 1024, 'x');
+        const QString firstPath = directory.filePath(QStringLiteral("first.bin"));
+        const QString samePath = directory.filePath(QStringLiteral("same.bin"));
+        const QString outsidePath = directory.filePath(QStringLiteral("outside.bin"));
+        const QString startPath = directory.filePath(QStringLiteral("start.bin"));
+        const QString middlePath = directory.filePath(QStringLiteral("middle.bin"));
+        const QString endPath = directory.filePath(QStringLiteral("end.bin"));
+
+        QVERIFY(writeFile(firstPath, content));
+        QVERIFY(writeFile(samePath, content));
+
+        QByteArray outside = content;
+        outside[1024 * 1024] = 'y';
+        QVERIFY(writeFile(outsidePath, outside));
+        QByteArray start = content;
+        start[0] = 'y';
+        QVERIFY(writeFile(startPath, start));
+        QByteArray middle = content;
+        middle[(content.size() - duplicateSampleBlockSize) / 2] = 'y';
+        QVERIFY(writeFile(middlePath, middle));
+        QByteArray end = content;
+        end[end.size() - 1] = 'y';
+        QVERIFY(writeFile(endPath, end));
+
+        const FileRecord first = recordFor(firstPath);
+        const QByteArray sample = sampleSha256(first);
+        QVERIFY(!sample.isEmpty());
+        QCOMPARE(sampleSha256(recordFor(samePath)), sample);
+        QCOMPARE(sampleSha256(recordFor(outsidePath)), sample);
+        QVERIFY(sampleSha256(recordFor(startPath)) != sample);
+        QVERIFY(sampleSha256(recordFor(middlePath)) != sample);
+        QVERIFY(sampleSha256(recordFor(endPath)) != sample);
+        QVERIFY(sha256(recordFor(outsidePath)) != sha256(first));
+
+        std::atomic_bool cancelled = true;
+        QVERIFY(sampleSha256(first, &cancelled).isEmpty());
+
+        const QString shortPath = directory.filePath(QStringLiteral("short.bin"));
+        QVERIFY(writeFile(shortPath, QByteArray("short")));
+        QVERIFY(sampleSha256(recordFor(shortPath)).isEmpty());
+        QVERIFY(!sha256(recordFor(shortPath)).isEmpty());
+
+        const QString emptyPath = directory.filePath(QStringLiteral("empty.bin"));
+        QVERIFY(writeFile(emptyPath, {}));
+        QVERIFY(sampleSha256(recordFor(emptyPath)).isEmpty());
+        QVERIFY(!sha256(recordFor(emptyPath)).isEmpty());
+
+        const QString replacedPath = directory.filePath(QStringLiteral("replaced.bin"));
+        QVERIFY(writeFile(replacedPath, content));
+        const FileRecord replaced = recordFor(replacedPath);
+        QVERIFY(QFile::remove(replacedPath));
+        QVERIFY(writeFile(replacedPath, content));
+        QVERIFY(!fileSignatureMatches(replaced));
+        QVERIFY(sha256(replaced).isEmpty());
+        QVERIFY(sampleSha256(replaced).isEmpty());
+
+        FileRecord missing = first;
+        missing.path = directory.filePath(QStringLiteral("missing.bin"));
+        QVERIFY(sha256(missing).isEmpty());
+        QVERIFY(sampleSha256(missing).isEmpty());
+    }
 };
 
 QTEST_GUILESS_MAIN(SearchCoreTest)

tests/search_engine_test.cpp

@@ -0,0 +1,408 @@
+#include "search_engine.h"
+
+#include <QDateTime>
+#include <QDir>
+#include <QElapsedTimer>
+#include <QFile>
+#include <QSignalSpy>
+#include <QTemporaryDir>
+#include <QtTest>
+
+#include <algorithm>
+#include <unistd.h>
+
+namespace {
+bool writeFile(const QString &path, const QByteArray &data)
+{
+    QFile file(path);
+    return file.open(QIODevice::WriteOnly)
+        && file.write(data) == data.size();
+}
+
+QVector<FileRecord> runSearch(SearchEngine &engine, SearchOptions options)
+{
+    QSignalSpy finished(&engine, &SearchEngine::finished);
+    engine.search(options);
+    if (finished.size() != 1)
+        return {};
+    return finished.takeFirst().at(0).value<QVector<FileRecord>>();
+}
+
+QSet<QString> namesOf(const QVector<FileRecord> &records)
+{
+    QSet<QString> names;
+    for (const auto &record : records)
+        names.insert(record.name);
+    return names;
+}
+
+SearchOptions optionsFor(const QString &root, const QString &mode)
+{
+    SearchOptions options;
+    options.roots = root;
+    options.mode = mode;
+    options.recursive = true;
+    options.accurateProgress = false;
+    options.showDuplicateCopiesOnly = false;
+    options.useCache = false;
+    return options;
+}
+}
+
+class SearchEngineTest final : public QObject {
+    Q_OBJECT
+
+private slots:
+    void filtersBySampleThenFullHashAndSupportsStrictMode()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("duplicate-a.bin")),
+                          QByteArray("same content")));
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("duplicate-b.bin")),
+                          QByteArray("same content")));
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("unique-size.bin")),
+                          QByteArray("unique")));
+
+        const QByteArray large(duplicateSampleThreshold + 1024 * 1024, 'x');
+        QByteArray different = large;
+        different[1024 * 1024] = 'y';
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("sample-a.bin")), large));
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("sample-b.bin")), different));
+
+        SearchEngine engine(nullptr, directory.filePath(QStringLiteral("cache.dat")));
+        SearchOptions options = optionsFor(
+            directory.path(), QStringLiteral("Duplicates search"));
+        QVector<FileRecord> results = runSearch(engine, options);
+        QCOMPARE(namesOf(results),
+                 QSet<QString>({QStringLiteral("duplicate-a.bin"),
+                                QStringLiteral("duplicate-b.bin")}));
+
+        options.strictDuplicateComparison = true;
+        results = runSearch(engine, options);
+        QCOMPARE(namesOf(results),
+                 QSet<QString>({QStringLiteral("duplicate-a.bin"),
+                                QStringLiteral("duplicate-b.bin")}));
+
+        options.mode = QStringLiteral("Non-Duplicates search");
+        results = runSearch(engine, options);
+        QCOMPARE(namesOf(results),
+                 QSet<QString>({QStringLiteral("unique-size.bin"),
+                                QStringLiteral("sample-a.bin"),
+                                QStringLiteral("sample-b.bin")}));
+    }
+
+    void appliesContentPipelineToDuplicateNames()
+    {
+        QTemporaryDir directory;
+        QVERIFY(directory.isValid());
+        QDir root(directory.path());
+        QVERIFY(root.mkpath(QStringLiteral("one")));
+        QVERIFY(root.mkpath(QStringLiteral("two")));
+        const QString first =
+            directory.filePath(QStringLiteral("one/report.bin"));
+        const QString second =
+            directory.filePath(QStringLiteral("two/report.bin"));
+        QVERIFY(writeFile(first, QByteArray("same")));
+        QVERIFY(writeFile(second, QByteArray("same")));
+
+        SearchEngine engine(nullptr, directory.filePath(QStringLiteral("cache.dat")));
+        SearchOptions options = optionsFor(
+            directory.path(), QStringLiteral("Duplicate names search"));
+        options.duplicateNameMode = QStringLiteral("Only identical content");
+        QVector<FileRecord> results = runSearch(engine, options);
+        QCOMPARE(results.size(), 2);
+
+        QVERIFY(writeFile(second, QByteArray("diff")));
+        results = runSearch(engine, options);
+        QVERIFY(results.isEmpty());
+
+        options.duplicateNameMode = QStringLiteral("Only non-identical content");
+        results = runSearch(engine, options);
+        QCOMPARE(results.size(), 2);
+
+        options.strictDuplicateComparison = true;
+        results = runSearch(engine, options);
+        QCOMPARE(results.size(), 2);
+    }
+
+    void assignsKeeperPriorityFromConfiguredRoots()
+    {
+        QTemporaryDir directory;
+        QTemporaryDir cacheDirectory;
+        QVERIFY(directory.isValid());
+        QVERIFY(cacheDirectory.isValid());
+        QDir root(directory.path());
+        QVERIFY(root.mkpath(QStringLiteral("Temp")));
+        QVERIFY(root.mkpath(QStringLiteral("misc")));
+        const QString temp = directory.filePath(QStringLiteral("Temp"));
+        const QString misc = directory.filePath(QStringLiteral("misc"));
+        const QByteArray content("same");
+        const QString basePath = directory.filePath(QStringLiteral("base.mp4"));
+        const QString tempPath = QDir(temp).filePath(QStringLiteral("temp.mp4"));
+        const QString miscPath = QDir(misc).filePath(QStringLiteral("misc.mp4"));
+        QVERIFY(writeFile(basePath, content));
+        QVERIFY(writeFile(tempPath, content));
+        QVERIFY(writeFile(miscPath, content));
+
+        SearchEngine engine(nullptr, cacheDirectory.filePath(QStringLiteral("cache.dat")));
+        SearchOptions options = optionsFor(
+            QStringList({directory.path(), temp, misc}).join(u';'),
+            QStringLiteral("Duplicates search"));
+        QVector<FileRecord> results = runSearch(engine, options);
+        QCOMPARE(results.size(), 3);
+
+        QHash<QString, int> priorities;
+        for (const FileRecord &record : results)
+            priorities.insert(record.path, record.duplicateCopy);
+        QCOMPARE(priorities.value(basePath), 1);
+        QCOMPARE(priorities.value(tempPath), 2);
+        QCOMPARE(priorities.value(miscPath), 3);
+    }
+
+    void prefersNewerFilesWhenRootPriorityTies()
+    {
+        QTemporaryDir directory;
+        QTemporaryDir cacheDirectory;
+        QVERIFY(directory.isValid());
+        QVERIFY(cacheDirectory.isValid());
+        QDir root(directory.path());
+        QVERIFY(root.mkpath(QStringLiteral("child")));
+        const QString older = QDir(directory.filePath(QStringLiteral("child")))
+                                  .filePath(QStringLiteral("older.mp4"));
+        const QString newer = directory.filePath(QStringLiteral("newer.mp4"));
+        QVERIFY(writeFile(older, QByteArray("same")));
+        QVERIFY(writeFile(newer, QByteArray("same")));
+        QFile olderFile(older);
+        QVERIFY(olderFile.open(QIODevice::ReadOnly));
+        QVERIFY(olderFile.setFileTime(QDateTime::fromSecsSinceEpoch(1),
+                                      QFileDevice::FileModificationTime));
+        olderFile.close();
+
+        SearchEngine engine(nullptr, cacheDirectory.filePath(QStringLiteral("cache.dat")));
+        SearchOptions options = optionsFor(
+            directory.path(), QStringLiteral("Duplicates search"));
+        const QVector<FileRecord> results = runSearch(engine, options);
+        QCOMPARE(results.size(), 2);
+        QHash<QString, int> priorities;
+        for (const FileRecord &record : results)
+            priorities.insert(record.path, record.duplicateCopy);
+        QCOMPARE(priorities.value(newer), 1);
+        QCOMPARE(priorities.value(older), 2);
+    }
+
+    void reusesSampleAndFullHashesOnWarmSearch()
+    {
+        QTemporaryDir directory;
+        QTemporaryDir cacheDirectory;
+        QVERIFY(directory.isValid());
+        QVERIFY(cacheDirectory.isValid());
+        const QByteArray content(duplicateSampleThreshold + 1024 * 1024, 'x');
+        const QString first = directory.filePath(QStringLiteral("first.bin"));
+        const QString second = directory.filePath(QStringLiteral("second.bin"));
+        QVERIFY(writeFile(first, content));
+        QVERIFY(writeFile(second, content));
+        const QString cachePath =
+            cacheDirectory.filePath(QStringLiteral("duplicate-cache.dat"));
+        SearchEngine engine(nullptr, cachePath);
+        SearchOptions options = optionsFor(
+            directory.path(), QStringLiteral("Duplicates search"));
+        options.useCache = true;
+
+        QSignalSpy finished(&engine, &SearchEngine::finished);
+        QElapsedTimer timer;
+        timer.start();
+        engine.search(options);
+        const qint64 coldMilliseconds = timer.elapsed();
+        QCOMPARE(finished.size(), 1);
+        finished.clear();
+
+        if (::geteuid() != 0) {
+            QVERIFY(QFile::setPermissions(first, {}));
+            QVERIFY(QFile::setPermissions(second, {}));
+        }
+        timer.restart();
+        engine.search(options);
+        const qint64 warmMilliseconds = timer.elapsed();
+        QCOMPARE(finished.size(), 1);
+        const QList<QVariant> arguments = finished.takeFirst();
+        QCOMPARE(arguments.at(0).value<QVector<FileRecord>>().size(), 2);
+        QVERIFY(arguments.at(1).toString().contains(QStringLiteral("cache: 4 hits")));
+        qInfo().noquote()
+            << QStringLiteral("duplicate benchmark: cold %1 ms, warm %2 ms")
+                   .arg(coldMilliseconds)
+                   .arg(warmMilliseconds);
+
+        if (::geteuid() != 0) {
+            options.strictDuplicateComparison = true;
+            finished.clear();
+            engine.search(options);
+            QCOMPARE(finished.size(), 1);
+            QVERIFY(finished.takeFirst().at(0).value<QVector<FileRecord>>().isEmpty());
+        }
+        QFile::remove(cachePath);
+    }
+
+    void doesNotFullyHashDifferentSamplesOrSizes()
+    {
+        QTemporaryDir directory;
+        QTemporaryDir cacheDirectory;
+        QVERIFY(directory.isValid());
+        QVERIFY(cacheDirectory.isValid());
+        const QByteArray firstContent(
+            duplicateSampleThreshold + 1024 * 1024, 'x');
+        QByteArray secondContent = firstContent;
+        secondContent[0] = 'y';
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("large-a.bin")),
+                          firstContent));
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("large-b.bin")),
+                          secondContent));
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("small-a.bin")),
+                          QByteArray("one")));
+        QVERIFY(writeFile(directory.filePath(QStringLiteral("small-b.bin")),
+                          QByteArray("different size")));
+
+        SearchEngine engine(
+            nullptr, cacheDirectory.filePath(QStringLiteral("cache.dat")));
+        SearchOptions options = optionsFor(
+            directory.path(), QStringLiteral("Duplicates search"));
+        options.useCache = true;
+        QSignalSpy finished(&engine, &SearchEngine::finished);
+        engine.search(options);
+        QCOMPARE(finished.size(), 1);
+        finished.clear();
+
+        engine.search(options);
+        QCOMPARE(finished.size(), 1);
+        const QList<QVariant> arguments = finished.takeFirst();
+        QVERIFY(arguments.at(0).value<QVector<FileRecord>>().isEmpty());
+        QVERIFY(arguments.at(1).toString().contains(QStringLiteral("cache: 2 hits")));
+    }
+
+    void collapsesCurrentOverlappingRootLayoutBeforeHashing()
+    {
+        QTemporaryDir directory;
+        QTemporaryDir cacheDirectory;
+        QVERIFY(directory.isValid());
+        QVERIFY(cacheDirectory.isValid());
+        QDir root(directory.path());
+        const QStringList children{
+            QStringLiteral(".Prt"), QStringLiteral("misc"), QStringLiteral("Music"),
+            QStringLiteral("Буфер"), QStringLiteral("Temp")
+        };
+        QStringList roots{directory.path()};
+        for (qsizetype index = 0; index < children.size(); ++index) {
+            QVERIFY(root.mkpath(children[index]));
+            const QString child = directory.filePath(children[index]);
+            roots.push_back(child);
+            QVERIFY(writeFile(
+                QDir(child).filePath(QStringLiteral("unique.bin")),
+                QByteArray(duplicateSampleThreshold + index + 1,
+                           char('a' + index))));
+        }
+
+        SearchEngine engine(
+            nullptr, cacheDirectory.filePath(QStringLiteral("cache.dat")));
+        SearchOptions options = optionsFor(
+            roots.join(u';'), QStringLiteral("Duplicates search"));
+        options.accurateProgress = true;
+        options.excludeFolders =
+            directory.filePath(QStringLiteral("Meta"));
+        QSignalSpy phases(&engine, &SearchEngine::phaseProgress);
+        QSignalSpy finished(&engine, &SearchEngine::finished);
+        QElapsedTimer timer;
+        timer.start();
+        engine.search(options);
+        const qint64 elapsedMilliseconds = timer.elapsed();
+
+        QCOMPARE(finished.size(), 1);
+        const QList<QVariant> arguments = finished.takeFirst();
+        QVERIFY(arguments.at(0).value<QVector<FileRecord>>().isEmpty());
+        QVERIFY(arguments.at(1).toString().contains(
+            QStringLiteral("5 redundant roots skipped")));
+        quint64 scanningCompleted = 0;
+        quint64 scanningTotal = 0;
+        for (const QList<QVariant> &phase : phases) {
+            const QString name = phase.at(0).toString();
+            QVERIFY(name != QStringLiteral("Sampling duplicate candidates"));
+            QVERIFY(name != QStringLiteral("Hashing duplicate candidates"));
+            if (name == QStringLiteral("Scanning files")) {
+                scanningCompleted =
+                    std::max(scanningCompleted, phase.at(1).toULongLong());
+                scanningTotal = phase.at(2).toULongLong();
+            }
+        }
+        QVERIFY(scanningTotal > 0);
+        QCOMPARE(scanningCompleted, scanningTotal);
+        qInfo().noquote()
+            << QStringLiteral("overlapping-roots benchmark: %1 ms, 5 large files, 0 hash phases")
+                   .arg(elapsedMilliseconds);
+    }
+
+    void deduplicatesCandidatesWhenNestedRootsCannotBeCollapsed()
+    {
+        QTemporaryDir directory;
+        QTemporaryDir cacheDirectory;
+        QVERIFY(directory.isValid());
+        QVERIFY(cacheDirectory.isValid());
+        QDir root(directory.path());
+        QVERIFY(root.mkpath(QStringLiteral("child")));
+        const QString child = directory.filePath(QStringLiteral("child"));
+        QVERIFY(writeFile(QDir(child).filePath(QStringLiteral("only.bin")),
+                          QByteArray(duplicateSampleThreshold + 1, 'x')));
+
+        SearchEngine engine(
+            nullptr, cacheDirectory.filePath(QStringLiteral("cache.dat")));
+        SearchOptions options = optionsFor(
+            directory.path() + u';' + child, QStringLiteral("Standard search"));
+        options.maxDepth = 2;
+        QVector<FileRecord> results = runSearch(engine, options);
+        QCOMPARE(results.size(), 1);
+        QCOMPARE(results.front().name, QStringLiteral("only.bin"));
+
+        options.mode = QStringLiteral("Duplicates search");
+        QSignalSpy phases(&engine, &SearchEngine::phaseProgress);
+        QSignalSpy finished(&engine, &SearchEngine::finished);
+        engine.search(options);
+        QCOMPARE(finished.size(), 1);
+        const QList<QVariant> arguments = finished.takeFirst();
+        QVERIFY(arguments.at(0).value<QVector<FileRecord>>().isEmpty());
+        QVERIFY(!arguments.at(1).toString().contains(
+            QStringLiteral("redundant roots skipped")));
+        for (const QList<QVariant> &phase : phases) {
+            const QString name = phase.at(0).toString();
+            QVERIFY(name != QStringLiteral("Sampling duplicate candidates"));
+            QVERIFY(name != QStringLiteral("Hashing duplicate candidates"));
+        }
+    }
+
+    void leavesUnreadableCandidatesAsNonDuplicates()
+    {
+        if (::geteuid() == 0)
+            QSKIP("Root can read files regardless of their permission bits");
+        QTemporaryDir directory;
+        QTemporaryDir cacheDirectory;
+        QVERIFY(directory.isValid());
+        QVERIFY(cacheDirectory.isValid());
+        const QString first = directory.filePath(QStringLiteral("first.bin"));
+        const QString second = directory.filePath(QStringLiteral("second.bin"));
+        QVERIFY(writeFile(first, QByteArray("blocked")));
+        QVERIFY(writeFile(second, QByteArray("blocked")));
+        QVERIFY(QFile::setPermissions(first, {}));
+        QVERIFY(QFile::setPermissions(second, {}));
+
+        SearchEngine engine(
+            nullptr, cacheDirectory.filePath(QStringLiteral("cache.dat")));
+        SearchOptions options = optionsFor(
+            directory.path(), QStringLiteral("Duplicates search"));
+        QVERIFY(runSearch(engine, options).isEmpty());
+        options.mode = QStringLiteral("Non-Duplicates search");
+        QCOMPARE(namesOf(runSearch(engine, options)),
+                 QSet<QString>({QStringLiteral("first.bin"),
+                                QStringLiteral("second.bin")}));
+    }
+};
+
+QTEST_GUILESS_MAIN(SearchEngineTest)
+
+#include "search_engine_test.moc"