Undo/redo

CMakeLists.txt

@@ -33,7 +33,7 @@ pkg_check_modules(SPA REQUIRED libspa-0.2>=0.2)
 add_compile_options(
     -Wall
     -Wextra
-    -Wpedantic
+    -Wno-pedantic
     -Werror=return-type
 )
 
@@ -90,6 +90,7 @@ add_executable(potato-gui
     src/gui/GraphEditorWidget.cpp
     src/gui/PipeWireGraphModel.cpp
     src/meters/AudioLevelMeter.cpp
+    src/presets/PresetManager.cpp
 )
 
 target_link_libraries(potato-gui PRIVATE

PROJECT_PLAN.md

@@ -1191,52 +1191,52 @@ private:
 
 ## 11. Implementation Milestone Plan
 
-### Milestone 1: Core PipeWire Integration ✅
+### Milestone 1: Core PipeWire Integration
 **Estimated Time:** 2-3 weeks
-- [ ] Initialize Qt6 project with CMake
-- [ ] Integrate libpipewire with `pw_thread_loop`
-- [ ] Implement node/port discovery via registry callbacks
-- [ ] Implement link creation/destruction
-- [ ] Create lock-free communication primitives (atomics, ring buffers)
-- [ ] **Acceptance Criteria:** CLI test app that lists nodes and creates a link programmatically
+- [x] Initialize Qt6 project with CMake
+- [x] Integrate libpipewire with `pw_thread_loop`
+- [x] Implement node/port discovery via registry callbacks
+- [x] Implement link creation/destruction
+- [x] Create lock-free communication primitives (atomics, ring buffers)
+- [x] **Acceptance Criteria:** CLI test app that lists nodes and creates a link programmatically
 
-### Milestone 2: QtNodes Integration ✅
+### Milestone 2: QtNodes Integration
 **Estimated Time:** 2-3 weeks
-- [ ] Integrate QtNodes library (submodule or CMake package)
-- [ ] Create `AudioNodeDataModel` for PipeWire nodes
-- [ ] Map PipeWire ports to QtNodes handles
-- [ ] Implement connection validation
-- [ ] Create custom node widgets with embedded controls
-- [ ] **Acceptance Criteria:** Visual graph editor displays PipeWire nodes and allows dragging connections
+- [x] Integrate QtNodes library (submodule or CMake package)
+- [x] Create `AudioNodeDataModel` for PipeWire nodes
+- [x] Map PipeWire ports to QtNodes handles
+- [x] Implement connection validation
+- [x] Create custom node widgets with embedded controls
+- [x] **Acceptance Criteria:** Visual graph editor displays PipeWire nodes and allows dragging connections
 
-### Milestone 3: Real-Time Meters & Performance ✅
+### Milestone 3: Real-Time Meters & Performance
 **Estimated Time:** 1-2 weeks
-- [ ] Implement `AudioLevelMeter` with optimized QGraphicsView
-- [ ] Create 30Hz update timer with manual viewport control
-- [ ] Integrate PipeWire audio callbacks for meter data
-- [ ] Implement lock-free meter data transfer (atomics)
-- [ ] Profile and optimize rendering performance
+- [x] Implement `AudioLevelMeter` with optimized QGraphicsView
+- [x] Create 30Hz update timer with manual viewport control
+- [x] Integrate PipeWire audio callbacks for meter data
+- [x] Implement lock-free meter data transfer (atomics)
+- [x] Profile and optimize rendering performance
 - [ ] **Acceptance Criteria:** Smooth 30Hz meters with no GUI lag, validated with profiler
 
-### Milestone 4: Virtual Devices & State Management ✅
+### Milestone 4: Virtual Devices & State Management
 **Estimated Time:** 2 weeks
-- [ ] Implement virtual sink/source creation via PipeWire adapters
-- [ ] Create `PresetManager` with JSON serialization
-- [ ] Implement preset load/save functionality
-- [ ] Store UI layout alongside audio graph state
+- [x] Implement virtual sink/source creation via PipeWire adapters
+- [x] Create `PresetManager` with JSON serialization
+- [x] Implement preset load/save functionality
+- [x] Store UI layout alongside audio graph state
 - [ ] Implement auto-reconnect for device hotplug
 - [ ] **Acceptance Criteria:** Create virtual device, save preset, restore on restart
 
-### Milestone 5: Mixer View & Volume Control ✅
+### Milestone 5: Mixer View & Volume Control
 **Estimated Time:** 1-2 weeks
-- [ ] Design traditional mixer UI with faders
-- [ ] Implement volume slider with PipeWire parameter sync
-- [ ] Add mute buttons and solo functionality
-- [ ] Create stereo/multi-channel level meters
-- [ ] Implement undo/redo for volume changes
+- [x] Design traditional mixer UI with faders
+- [x] Implement volume slider with PipeWire parameter sync
+- [x] Add mute buttons and solo functionality
+- [x] Create stereo/multi-channel level meters
+- [x] Implement undo/redo for volume changes
 - [ ] **Acceptance Criteria:** Mixer panel controls node volumes, changes persist in presets
 
-### Milestone 6: Undo/Redo & Polish ✅
+### Milestone 6: Undo/Redo & Polish
 **Estimated Time:** 1-2 weeks
 - [ ] Integrate QUndoStack for all graph operations
 - [ ] Implement command classes for link, volume, node operations
@@ -1245,7 +1245,7 @@ private:
 - [ ] Add copy/paste/duplicate functionality
 - [ ] **Acceptance Criteria:** Full undo/redo history, keyboard shortcuts work
 
-### Milestone 7: Error Handling & Edge Cases ✅
+### Milestone 7: Error Handling & Edge Cases
 **Estimated Time:** 1-2 weeks
 - [ ] Implement device unplug/replug detection
 - [ ] Handle PipeWire service restart with auto-reconnect
@@ -1254,7 +1254,7 @@ private:
 - [ ] Add error logging with structured JSON output
 - [ ] **Acceptance Criteria:** App survives device unplug and PipeWire restart without crashing
 
-### Milestone 8: Final Polish & Release ✅
+### Milestone 8: Final Polish & Release
 **Estimated Time:** 1-2 weeks
 - [ ] Create application icon and desktop file
 - [ ] Implement dark/light theme support

src/gui/ClickSlider.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <QMouseEvent>
+#include <QSlider>
+#include <QStyle>
+
+class ClickSlider : public QSlider
+{
+public:
+    using QSlider::QSlider;
+
+protected:
+    void mousePressEvent(QMouseEvent *event) override
+    {
+        if (event->button() == Qt::LeftButton) {
+            setProperty("pressValue", value());
+            const int span = (orientation() == Qt::Horizontal) ? width() : height();
+            const int pos = (orientation() == Qt::Horizontal)
+                ? static_cast<int>(event->position().x())
+                : static_cast<int>(height() - event->position().y());
+            const int value = QStyle::sliderValueFromPosition(minimum(), maximum(), pos, span);
+            setValue(value);
+            event->accept();
+        }
+        QSlider::mousePressEvent(event);
+    }
+};

src/gui/GraphEditorWidget.cpp

@@ -1,23 +1,70 @@
 #include "GraphEditorWidget.h"
 #include "meters/AudioLevelMeter.h"
+#include "presets/PresetManager.h"
 
 #include <QAction>
 #include <QCoreApplication>
+#include <QDebug>
 #include <QColor>
 #include <QFileDialog>
 #include <QFontMetrics>
 #include <QLabel>
 #include <QHBoxLayout>
 #include <QSplitter>
+#include <QTabWidget>
+#include <QSlider>
+#include <QToolButton>
 #include <QTimer>
+#include <QUndoCommand>
 #include <QEvent>
 #include <QVBoxLayout>
 #include <QScrollArea>
 #include <QSizePolicy>
+#include <QElapsedTimer>
+#include <algorithm>
+#include <cmath>
 
 #include <QtNodes/GraphicsViewStyle>
 #include <QtNodes/NodeStyle>
 
+#include "gui/ClickSlider.h"
+
+class VolumeChangeCommand : public QUndoCommand
+{
+public:
+    VolumeChangeCommand(GraphEditorWidget *widget,
+                        uint32_t nodeId,
+                        const NodeVolumeState &previous,
+                        const NodeVolumeState &next)
+        : m_widget(widget)
+        , m_nodeId(nodeId)
+        , m_previous(previous)
+        , m_next(next)
+    {
+        setText(QString("Volume Change"));
+    }
+
+    void undo() override
+    {
+        if (m_widget) {
+            m_widget->applyVolumeState(m_nodeId, m_previous, true);
+        }
+    }
+
+    void redo() override
+    {
+        if (m_widget) {
+            m_widget->applyVolumeState(m_nodeId, m_next, true);
+        }
+    }
+
+private:
+    GraphEditorWidget *m_widget = nullptr;
+    uint32_t m_nodeId = 0;
+    NodeVolumeState m_previous{};
+    NodeVolumeState m_next{};
+};
+
 GraphEditorWidget::GraphEditorWidget(Potato::PipeWireController *controller, QWidget *parent)
     : QWidget(parent)
     , m_controller(controller)
@@ -65,8 +112,16 @@ GraphEditorWidget::GraphEditorWidget(Potato::PipeWireController *controller, QWi
     m_splitter->setOrientation(Qt::Horizontal);
     m_splitter->addWidget(m_view);
 
-    auto *meterPanel = new QWidget(m_splitter);
-    meterPanel->setStyleSheet("background-color: #1f2126; border-left: 1px solid #2b2f38;");
+    m_sidebarTabs = new QTabWidget(m_splitter);
+    m_sidebarTabs->setStyleSheet(
+        "QTabWidget::pane { border: none; background: #1f2126; border-left: 1px solid #2b2f38; }"
+        "QTabBar::tab { background: #1f2126; color: #8c94a5; padding: 8px 12px; border: none; font-weight: 700; font-size: 11px; }"
+        "QTabBar::tab:selected { color: #dbe2ee; border-bottom: 2px solid #5fcf8d; }"
+        "QTabBar::tab:hover { color: #c7cfdd; }"
+    );
+
+    auto *meterPanel = new QWidget();
+    meterPanel->setStyleSheet("background-color: #1f2126;");
     meterPanel->setMinimumWidth(260);
     meterPanel->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Expanding);
     
@@ -102,7 +157,31 @@ GraphEditorWidget::GraphEditorWidget(Potato::PipeWireController *controller, QWi
 
     meterLayout->addStretch();
 
-    m_splitter->addWidget(meterPanel);
+    m_sidebarTabs->addTab(meterPanel, "METERS");
+
+    m_mixerTab = new QWidget();
+    m_mixerTab->setStyleSheet("background-color: #1f2126;");
+    auto *mixerTabLayout = new QVBoxLayout(m_mixerTab);
+    mixerTabLayout->setContentsMargins(0, 0, 0, 0);
+
+    auto *mixerScroll = new QScrollArea(m_mixerTab);
+    mixerScroll->setFrameShape(QFrame::NoFrame);
+    mixerScroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    mixerScroll->setWidgetResizable(true);
+    
+    m_mixerList = new QWidget(mixerScroll);
+    m_mixerListLayout = new QHBoxLayout(m_mixerList);
+    m_mixerListLayout->setContentsMargins(20, 20, 20, 20);
+    m_mixerListLayout->setSpacing(12);
+    m_mixerListLayout->setAlignment(Qt::AlignLeft);
+    m_mixerList->setLayout(m_mixerListLayout);
+    
+    mixerScroll->setWidget(m_mixerList);
+    mixerTabLayout->addWidget(mixerScroll);
+    
+    m_sidebarTabs->addTab(m_mixerTab, "MIXER");
+
+    m_splitter->addWidget(m_sidebarTabs);
     m_splitter->setStretchFactor(0, 1);
     m_splitter->setStretchFactor(1, 0);
 
@@ -115,6 +194,16 @@ GraphEditorWidget::GraphEditorWidget(Potato::PipeWireController *controller, QWi
             this, &GraphEditorWidget::onConnectionCreated);
     connect(m_model, &PipeWireGraphModel::connectionDeleted,
             this, &GraphEditorWidget::onConnectionDeleted);
+    connect(m_model, &PipeWireGraphModel::nodeVolumeChanged,
+            this, [this](uint32_t nodeId, const NodeVolumeState &previous, const NodeVolumeState &current) {
+                if (m_ignoreVolumeUndo) {
+                    return;
+                }
+                pushVolumeCommand(nodeId, previous, current);
+                if (m_mixerFaders.contains(nodeId)) {
+                    m_mixerLastState.insert(nodeId, current);
+                }
+            });
 
     connect(m_controller, &Potato::PipeWireController::nodeAdded,
             this, &GraphEditorWidget::onNodeAdded);
@@ -172,6 +261,61 @@ GraphEditorWidget::GraphEditorWidget(Potato::PipeWireController *controller, QWi
     });
     m_view->addAction(resetLayoutAction);
 
+
+    auto *savePresetAction = new QAction(QString("Save Preset..."), m_view);
+    connect(savePresetAction, &QAction::triggered, [this]() {
+        const QString filePath = QFileDialog::getSaveFileName(this,
+            QString("Save Preset"),
+            QString(),
+            QString("Preset Files (*.json)"));
+        if (filePath.isEmpty()) {
+            return;
+        }
+        if (!m_presetManager->savePreset(filePath)) {
+            qWarning() << "Failed to save preset" << filePath;
+        }
+    });
+    m_view->addAction(savePresetAction);
+
+    auto *loadPresetAction = new QAction(QString("Load Preset..."), m_view);
+    connect(loadPresetAction, &QAction::triggered, [this]() {
+        const QString filePath = QFileDialog::getOpenFileName(this,
+            QString("Load Preset"),
+            QString(),
+            QString("Preset Files (*.json)"));
+        if (filePath.isEmpty()) {
+            return;
+        }
+        if (!m_presetManager->loadPreset(filePath)) {
+            qWarning() << "Failed to load preset" << filePath;
+            return;
+        }
+        reloadGraphFromController();
+    });
+    m_view->addAction(loadPresetAction);
+
+    auto *createVirtualSinkAction = new QAction(QString("Create Virtual Sink"), m_view);
+    connect(createVirtualSinkAction, &QAction::triggered, [this]() {
+        const int index = ++m_virtualSinkCount;
+        const QString name = QString("Potato_Virtual_Sink_%1").arg(index);
+        const QString description = QString("Virtual Sink %1").arg(index);
+        if (!m_controller->createVirtualSink(name, description, 2, 48000)) {
+            qWarning() << "Failed to create virtual sink" << name;
+        }
+    });
+    m_view->addAction(createVirtualSinkAction);
+
+    auto *createVirtualSourceAction = new QAction(QString("Create Virtual Source"), m_view);
+    connect(createVirtualSourceAction, &QAction::triggered, [this]() {
+        const int index = ++m_virtualSourceCount;
+        const QString name = QString("Potato_Virtual_Source_%1").arg(index);
+        const QString description = QString("Virtual Source %1").arg(index);
+        if (!m_controller->createVirtualSource(name, description, 2, 48000)) {
+            qWarning() << "Failed to create virtual source" << name;
+        }
+    });
+    m_view->addAction(createVirtualSourceAction);
+
     syncGraph();
     if (m_model->hasOverlaps()) {
         m_model->autoArrange();
@@ -205,6 +349,11 @@ GraphEditorWidget::GraphEditorWidget(Potato::PipeWireController *controller, QWi
     m_meterTimer->setTimerType(Qt::PreciseTimer);
     connect(m_meterTimer, &QTimer::timeout, this, &GraphEditorWidget::updateMeter);
     m_meterTimer->start();
+
+    m_meterProfileTimer.start();
+    m_meterProfileReady = true;
+
+    m_presetManager = new PresetManager(m_controller, m_model, this);
 }
 
 static bool isAudioEndpoint(const Potato::NodeInfo &node)
@@ -225,6 +374,7 @@ void GraphEditorWidget::syncGraph()
         if (isAudioEndpoint(node)) {
             m_model->addPipeWireNode(node);
             refreshNodeMeter(node.id, node);
+            refreshMixerStrip(node.id, node);
         }
     }
     const QVector<Potato::LinkInfo> links = m_controller->links();
@@ -255,6 +405,7 @@ void GraphEditorWidget::onNodeAdded(const Potato::NodeInfo &node)
     if (isAudioEndpoint(node)) {
         m_model->addPipeWireNode(node);
         refreshNodeMeter(node.id, node);
+        refreshMixerStrip(node.id, node);
     }
 }
 
@@ -270,6 +421,8 @@ void GraphEditorWidget::onNodeChanged(const Potato::NodeInfo &node)
 
     refreshNodeMeter(node.id, node);
     updateNodeMeterState(node.id, node);
+    refreshMixerStrip(node.id, node);
+    updateMixerState(node.id, node);
 }
 
 void GraphEditorWidget::onNodeRemoved(uint32_t nodeId)
@@ -288,6 +441,8 @@ void GraphEditorWidget::onNodeRemoved(uint32_t nodeId)
         m_nodeMeters.remove(nodeId);
         row->deleteLater();
     }
+
+    removeMixerStrip(nodeId);
 }
 
 void GraphEditorWidget::onLinkAdded(const Potato::LinkInfo &link)
@@ -383,6 +538,7 @@ void GraphEditorWidget::onConnectionCreated(QtNodes::ConnectionId const connecti
 
     const uint32_t linkId = m_controller->createLink(outInfo->id, outputPortId, inInfo->id, inputPortId);
     if (linkId == 0) {
+        m_model->deleteConnection(connectionId);
         return;
     }
 
@@ -435,6 +591,12 @@ void GraphEditorWidget::updateMeter()
         return;
     }
 
+    if (!isVisible()) {
+        return;
+    }
+
+    const qint64 startNanos = m_meterProfileReady ? m_meterProfileTimer.nsecsElapsed() : 0;
+
     const float peak = m_controller->meterPeak();
     m_meter->setLevel(peak);
 
@@ -443,6 +605,27 @@ void GraphEditorWidget::updateMeter()
         const float nodePeak = m_controller->nodeMeterPeak(nodeId);
         it.value()->setLevel(nodePeak);
     }
+
+    for (auto it = m_mixerMeters.begin(); it != m_mixerMeters.end(); ++it) {
+        const uint32_t nodeId = static_cast<uint32_t>(it.key());
+        const float nodePeak = m_controller->nodeMeterPeak(nodeId);
+        it.value()->setLevel(nodePeak);
+    }
+
+    if (m_meterProfileReady) {
+        const qint64 duration = m_meterProfileTimer.nsecsElapsed() - startNanos;
+        m_meterProfileNanos += duration;
+        m_meterProfileMax = std::max(m_meterProfileMax, duration);
+        ++m_meterProfileFrames;
+        if (m_meterProfileFrames >= 300) {
+            const double avgMs = static_cast<double>(m_meterProfileNanos) / (1000000.0 * m_meterProfileFrames);
+            const double maxMs = static_cast<double>(m_meterProfileMax) / 1000000.0;
+            qInfo() << "Meter update avg" << avgMs << "ms max" << maxMs << "ms";
+            m_meterProfileNanos = 0;
+            m_meterProfileMax = 0;
+            m_meterProfileFrames = 0;
+        }
+    }
 }
 
 void GraphEditorWidget::updateLayoutState()
@@ -458,6 +641,28 @@ void GraphEditorWidget::updateLayoutState()
     }
 }
 
+void GraphEditorWidget::reloadGraphFromController()
+{
+    m_ignoreCreate.clear();
+    m_ignoreDelete.clear();
+    m_connectionToLinkId.clear();
+    m_linkIdToConnection.clear();
+    m_nodeLinkCounts.clear();
+    m_linksById.clear();
+
+    m_model->reset();
+    syncGraph();
+
+    double viewScale = 1.0;
+    QPointF viewCenter;
+    if (m_model->viewState(viewScale, viewCenter)) {
+        m_view->setupScale(viewScale);
+        m_view->centerOn(viewCenter);
+    } else {
+        m_view->zoomFitAll();
+    }
+}
+
 void GraphEditorWidget::refreshNodeMeter(uint32_t nodeId, const Potato::NodeInfo &node)
 {
     if (m_nodeMeterRows.contains(nodeId)) {
@@ -616,3 +821,242 @@ bool GraphEditorWidget::eventFilter(QObject *object, QEvent *event)
 
     return QWidget::eventFilter(object, event);
 }
+
+void GraphEditorWidget::refreshMixerStrip(uint32_t nodeId, const Potato::NodeInfo &node)
+{
+    if (m_mixerStrips.contains(nodeId)) {
+        return;
+    }
+
+    auto *strip = new QWidget(m_mixerList);
+    strip->setFixedWidth(90);
+    auto *layout = new QVBoxLayout(strip);
+    layout->setContentsMargins(0, 0, 0, 0);
+    layout->setSpacing(8);
+
+    auto *meter = new AudioLevelMeter(strip);
+    meter->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
+    
+    auto *fader = new ClickSlider(Qt::Vertical, strip);
+    fader->setRange(0, 100);
+    fader->setValue(100);
+    fader->setToolTip("Volume");
+    fader->setStyleSheet(
+        "QSlider::groove:vertical { width: 4px; background: #2b2f38; border-radius: 2px; }"
+        "QSlider::sub-page:vertical { background: #2b2f38; border-radius: 2px; }"
+        "QSlider::add-page:vertical { background: #5fcf8d; border-radius: 2px; }"
+        "QSlider::handle:vertical { height: 10px; margin: 0 -6px; background: #dbe2ee; border-radius: 5px; }"
+    );
+
+    auto *muteBtn = new QToolButton(strip);
+    muteBtn->setText("M");
+    muteBtn->setCheckable(true);
+    muteBtn->setFixedSize(24, 24);
+    muteBtn->setToolTip("Mute");
+    muteBtn->setStyleSheet(
+        "QToolButton { background: #2b2f38; color: #8c94a5; border: none; border-radius: 4px; font-weight: 700; }"
+        "QToolButton:checked { background: #c94f4f; color: #ffffff; }"
+        "QToolButton:hover { background: #3c4350; }"
+    );
+
+    auto *soloBtn = new QToolButton(strip);
+    soloBtn->setText("S");
+    soloBtn->setCheckable(true);
+    soloBtn->setFixedSize(24, 24);
+    soloBtn->setToolTip("Solo");
+    soloBtn->setStyleSheet(
+        "QToolButton { background: #2b2f38; color: #8c94a5; border: none; border-radius: 4px; font-weight: 700; }"
+        "QToolButton:checked { background: #e0b045; color: #ffffff; }"
+        "QToolButton:hover { background: #3c4350; }"
+    );
+
+    auto *label = new QLabel(node.description.isEmpty() ? node.name : node.description, strip);
+    label->setStyleSheet("color: #8c94a5; font-size: 10px; font-weight: 600;");
+    label->setAlignment(Qt::AlignCenter);
+    label->setWordWrap(true);
+    label->setMinimumHeight(48);
+
+    layout->addWidget(meter, 1);
+    layout->addWidget(fader, 0, Qt::AlignHCenter);
+    
+    auto *btnLayout = new QHBoxLayout();
+    btnLayout->setContentsMargins(0, 0, 0, 0);
+    btnLayout->setSpacing(4);
+    btnLayout->addWidget(muteBtn);
+    btnLayout->addWidget(soloBtn);
+    layout->addLayout(btnLayout);
+    
+    layout->addWidget(label);
+
+    m_mixerListLayout->addWidget(strip);
+
+    m_mixerStrips.insert(nodeId, strip);
+    m_mixerMeters.insert(nodeId, meter);
+    m_mixerFaders.insert(nodeId, fader);
+    m_mixerMutes.insert(nodeId, muteBtn);
+    m_mixerSolos.insert(nodeId, soloBtn);
+    m_mixerUserMute.insert(nodeId, false);
+    m_mixerLastState.insert(nodeId, NodeVolumeState{1.0f, false});
+
+    connect(fader, &QSlider::valueChanged, [this, nodeId](int value) {
+        if (!m_mixerMutes.contains(nodeId) || !m_mixerFaders.contains(nodeId)) {
+            return;
+        }
+        const float volume = static_cast<float>(value) / 100.0f;
+        const bool userMute = m_mixerUserMute.value(nodeId, false);
+        if (m_mixerFaders[nodeId]->isSliderDown()) {
+            if (!m_mixerStartState.contains(nodeId)) {
+                const NodeVolumeState previous = m_mixerLastState.value(nodeId, NodeVolumeState{volume, userMute});
+                m_mixerStartState.insert(nodeId, previous);
+            }
+        } else {
+            const NodeVolumeState previous = m_mixerLastState.value(nodeId, NodeVolumeState{volume, userMute});
+            const NodeVolumeState next{volume, userMute};
+            pushVolumeCommand(nodeId, previous, next);
+            m_mixerLastState.insert(nodeId, next);
+        }
+        applySoloState();
+    });
+
+    connect(fader, &QSlider::sliderPressed, [this, nodeId]() {
+        if (!m_mixerFaders.contains(nodeId)) {
+            return;
+        }
+        const float volume = static_cast<float>(m_mixerFaders[nodeId]->value()) / 100.0f;
+        const bool userMute = m_mixerUserMute.value(nodeId, false);
+        const NodeVolumeState previous = m_mixerLastState.value(nodeId, NodeVolumeState{volume, userMute});
+        m_mixerStartState.insert(nodeId, previous);
+    });
+
+    connect(fader, &QSlider::sliderReleased, [this, nodeId]() {
+        if (!m_mixerFaders.contains(nodeId)) {
+            return;
+        }
+        const float volume = static_cast<float>(m_mixerFaders[nodeId]->value()) / 100.0f;
+        const bool userMute = m_mixerUserMute.value(nodeId, false);
+        const NodeVolumeState previous = m_mixerStartState.value(nodeId, m_mixerLastState.value(nodeId, NodeVolumeState{volume, userMute}));
+        const NodeVolumeState next{volume, userMute};
+        m_mixerStartState.remove(nodeId);
+        pushVolumeCommand(nodeId, previous, next);
+        m_mixerLastState.insert(nodeId, next);
+    });
+
+    connect(muteBtn, &QToolButton::toggled, [this, nodeId](bool checked) {
+        if (!m_mixerFaders.contains(nodeId)) {
+            return;
+        }
+        const float volume = static_cast<float>(m_mixerFaders[nodeId]->value()) / 100.0f;
+        const bool previousMute = m_mixerUserMute.value(nodeId, false);
+        const NodeVolumeState previous{volume, previousMute};
+        const NodeVolumeState next{volume, checked};
+        m_mixerUserMute[nodeId] = checked;
+        applySoloState();
+        pushVolumeCommand(nodeId, previous, next);
+        m_mixerLastState.insert(nodeId, next);
+    });
+
+    connect(soloBtn, &QToolButton::toggled, [this, nodeId](bool checked) {
+        if (checked) {
+            m_mixerSoloNodes.insert(nodeId);
+        } else {
+            m_mixerSoloNodes.remove(nodeId);
+        }
+        applySoloState();
+    });
+
+    updateMixerState(nodeId, node);
+}
+
+void GraphEditorWidget::updateMixerState(uint32_t nodeId, const Potato::NodeInfo &node)
+{
+    if (!m_mixerFaders.contains(nodeId) || !m_mixerMutes.contains(nodeId)) {
+        return;
+    }
+    if (node.stableId.isEmpty() || !m_model) {
+        return;
+    }
+
+    NodeVolumeState state;
+    if (!m_model->nodeVolumeState(nodeId, state)) {
+        return;
+    }
+
+    auto *fader = m_mixerFaders.value(nodeId);
+    auto *muteBtn = m_mixerMutes.value(nodeId);
+    fader->blockSignals(true);
+    muteBtn->blockSignals(true);
+    fader->setValue(static_cast<int>(state.volume * 100.0f));
+    muteBtn->setChecked(state.mute);
+    fader->blockSignals(false);
+    muteBtn->blockSignals(false);
+    m_mixerUserMute[nodeId] = state.mute;
+    m_mixerLastState.insert(nodeId, state);
+    applySoloState();
+}
+
+void GraphEditorWidget::removeMixerStrip(uint32_t nodeId)
+{
+    if (m_mixerStrips.contains(nodeId)) {
+        auto *strip = m_mixerStrips.take(nodeId);
+        m_mixerMeters.remove(nodeId);
+        m_mixerFaders.remove(nodeId);
+        m_mixerMutes.remove(nodeId);
+        m_mixerSolos.remove(nodeId);
+    m_mixerUserMute.remove(nodeId);
+    m_mixerStartState.remove(nodeId);
+    m_mixerLastState.remove(nodeId);
+    m_mixerSoloNodes.remove(nodeId);
+        strip->deleteLater();
+    }
+}
+
+void GraphEditorWidget::applySoloState()
+{
+    for (auto it = m_mixerFaders.begin(); it != m_mixerFaders.end(); ++it) {
+        const uint32_t nodeId = static_cast<uint32_t>(it.key());
+        const float volume = static_cast<float>(it.value()->value()) / 100.0f;
+        const bool userMute = m_mixerUserMute.value(nodeId, false);
+        const bool soloActive = !m_mixerSoloNodes.isEmpty();
+        const bool effectiveMute = userMute || (soloActive && !m_mixerSoloNodes.contains(nodeId));
+        m_controller->setNodeVolume(nodeId, volume, effectiveMute);
+        if (m_model) {
+            m_model->setNodeVolumeState(nodeId, NodeVolumeState{volume, userMute}, false);
+        }
+    }
+}
+
+void GraphEditorWidget::applyVolumeState(uint32_t nodeId, const NodeVolumeState &state, bool updateMixer)
+{
+    Q_UNUSED(updateMixer)
+    m_ignoreVolumeUndo = true;
+    if (m_model) {
+        m_model->setNodeVolumeState(nodeId, state, false);
+    }
+    m_mixerUserMute[nodeId] = state.mute;
+    if (m_mixerFaders.contains(nodeId)) {
+        m_mixerFaders[nodeId]->blockSignals(true);
+        m_mixerFaders[nodeId]->setValue(static_cast<int>(state.volume * 100.0f));
+        m_mixerFaders[nodeId]->blockSignals(false);
+    }
+    if (m_mixerMutes.contains(nodeId)) {
+        m_mixerMutes[nodeId]->blockSignals(true);
+        m_mixerMutes[nodeId]->setChecked(state.mute);
+        m_mixerMutes[nodeId]->blockSignals(false);
+    }
+    m_mixerLastState.insert(nodeId, state);
+    m_mixerStartState.remove(nodeId);
+    applySoloState();
+    m_ignoreVolumeUndo = false;
+}
+
+void GraphEditorWidget::pushVolumeCommand(uint32_t nodeId, const NodeVolumeState &previous, const NodeVolumeState &next)
+{
+    if (!m_scene || m_ignoreVolumeUndo) {
+        return;
+    }
+    const bool changedVolume = qAbs(previous.volume - next.volume) > 0.0001f;
+    if (!changedVolume && previous.mute == next.mute) {
+        return;
+    }
+    m_scene->undoStack().push(new VolumeChangeCommand(this, nodeId, previous, next));
+}

src/gui/GraphEditorWidget.h

@@ -9,6 +9,7 @@
 #include <QWidget>
 #include <QSet>
 #include <QMap>
+#include <QElapsedTimer>
 #include <cstdint>
 
 class AudioLevelMeter;
@@ -16,12 +17,20 @@ class QLabel;
 class QTimer;
 class QScrollArea;
 class QVBoxLayout;
+class QHBoxLayout;
+class QSlider;
+class QToolButton;
 class QSplitter;
+class QTabWidget;
+class PresetManager;
+class VolumeChangeCommand;
 
 class GraphEditorWidget : public QWidget
 {
     Q_OBJECT
 
+    friend class VolumeChangeCommand;
+
 public:
     explicit GraphEditorWidget(Potato::PipeWireController *controller, QWidget *parent = nullptr);
 
@@ -42,9 +51,16 @@ private:
     void updateLayoutState();
     void updateNodeMeterLabel(QLabel *label);
     void updateNodeMeterState(uint32_t nodeId, const Potato::NodeInfo &node);
+    void refreshMixerStrip(uint32_t nodeId, const Potato::NodeInfo &node);
+    void updateMixerState(uint32_t nodeId, const Potato::NodeInfo &node);
+    void removeMixerStrip(uint32_t nodeId);
+    void applySoloState();
+    void applyVolumeState(uint32_t nodeId, const NodeVolumeState &state, bool updateMixer);
+    void pushVolumeCommand(uint32_t nodeId, const NodeVolumeState &previous, const NodeVolumeState &next);
     void handleLinkRemoved(uint32_t linkId);
     bool isMeterNode(uint32_t nodeId) const;
     int activeLinkCount(uint32_t nodeId) const;
+    void reloadGraphFromController();
     QString connectionKey(const QtNodes::ConnectionId &connectionId) const;
     bool eventFilter(QObject *object, QEvent *event) override;
 
@@ -54,11 +70,27 @@ private:
     QtNodes::GraphicsView *m_view = nullptr;
     QSplitter *m_splitter = nullptr;
 
+    QTabWidget *m_sidebarTabs = nullptr;
+    QWidget *m_mixerTab = nullptr;
+    QWidget *m_mixerList = nullptr;
+    QHBoxLayout *m_mixerListLayout = nullptr;
+    QMap<uint32_t, AudioLevelMeter*> m_mixerMeters;
+    QMap<uint32_t, QWidget*> m_mixerStrips;
+    QMap<uint32_t, QSlider*> m_mixerFaders;
+    QMap<uint32_t, QToolButton*> m_mixerMutes;
+    QMap<uint32_t, QToolButton*> m_mixerSolos;
+    QMap<uint32_t, bool> m_mixerUserMute;
+    QMap<uint32_t, NodeVolumeState> m_mixerStartState;
+    QMap<uint32_t, NodeVolumeState> m_mixerLastState;
+    QSet<uint32_t> m_mixerSoloNodes;
+
     QSet<QString> m_ignoreCreate;
     QSet<QString> m_ignoreDelete;
     QSet<uint32_t> m_ignoreLinkRemoved;
     QMap<QString, uint32_t> m_connectionToLinkId;
     QMap<uint32_t, QString> m_linkIdToConnection;
+    int m_virtualSinkCount = 0;
+    int m_virtualSourceCount = 0;
     AudioLevelMeter *m_meter = nullptr;
     QTimer *m_meterTimer = nullptr;
     QScrollArea *m_meterScroll = nullptr;
@@ -69,4 +101,11 @@ private:
     QMap<uint32_t, QLabel*> m_nodeMeterLabels;
     QMap<uint32_t, int> m_nodeLinkCounts;
     QMap<uint32_t, Potato::LinkInfo> m_linksById;
+    QElapsedTimer m_meterProfileTimer;
+    bool m_meterProfileReady = false;
+    qint64 m_meterProfileNanos = 0;
+    qint64 m_meterProfileMax = 0;
+    int m_meterProfileFrames = 0;
+    PresetManager *m_presetManager = nullptr;
+    bool m_ignoreVolumeUndo = false;
 };

src/gui/PipeWireGraphModel.cpp

@@ -16,11 +16,18 @@
 #include <QDir>
 #include <QFile>
 #include <QFileInfo>
+#include <QHBoxLayout>
+#include <QSlider>
+#include "gui/ClickSlider.h"
+#include <QSizePolicy>
+#include <QToolButton>
+#include <QWidget>
 
 #include <QtNodes/NodeStyle>
 #include <QtNodes/StyleCollection>
 
 #include <algorithm>
+#include <cmath>
 #include <unordered_set>
 #include <vector>
 
@@ -108,6 +115,103 @@ PipeWireGraphModel::PipeWireGraphModel(Potato::PipeWireController *controller, Q
     }
 }
 
+QWidget *PipeWireGraphModel::nodeWidget(QtNodes::NodeId nodeId) const
+{
+    auto it = m_nodeWidgets.find(nodeId);
+    if (it != m_nodeWidgets.end()) {
+        return it->second;
+    }
+
+    uint32_t pipewireId = 0;
+    auto nodeIt = m_nodes.find(nodeId);
+    if (nodeIt != m_nodes.end()) {
+        pipewireId = nodeIt->second.id;
+    }
+
+    auto *widget = new QWidget();
+    auto *layout = new QHBoxLayout(widget);
+    layout->setContentsMargins(6, 2, 6, 2);
+    layout->setSpacing(6);
+
+    auto *muteButton = new QToolButton(widget);
+    muteButton->setText("M");
+    muteButton->setCheckable(true);
+    muteButton->setFixedSize(20, 20);
+    muteButton->setToolTip(QString("Mute"));
+
+    auto *slider = new ClickSlider(Qt::Horizontal, widget);
+    slider->setRange(0, 100);
+    slider->setValue(100);
+    slider->setFixedHeight(18);
+    slider->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
+    slider->setToolTip(QString("Volume"));
+
+    if (pipewireId != 0 && m_nodeVolumeState.contains(pipewireId)) {
+        const NodeVolumeState state = m_nodeVolumeState.value(pipewireId);
+        slider->setValue(static_cast<int>(state.volume * 100.0f));
+        muteButton->setChecked(state.mute);
+    }
+
+    const auto applyVolume = [this, pipewireId, slider, muteButton]() {
+        if (!m_controller || pipewireId == 0) {
+            return;
+        }
+        const float volume = static_cast<float>(slider->value()) / 100.0f;
+        const NodeVolumeState next{volume, muteButton->isChecked()};
+        const NodeVolumeState previous = m_nodeVolumeState.value(pipewireId, next);
+        m_controller->setNodeVolume(pipewireId, volume, next.mute);
+        auto *self = const_cast<PipeWireGraphModel*>(this);
+        self->setNodeVolumeState(pipewireId, next, false);
+        if (!slider->isSliderDown() && !m_inlineStartState.contains(pipewireId)) {
+            self->emitNodeVolumeChanged(pipewireId, previous, next);
+        }
+    };
+
+    QObject::connect(slider, &QSlider::valueChanged, widget, [applyVolume](int) { applyVolume(); });
+    QObject::connect(muteButton, &QToolButton::toggled, widget, [applyVolume](bool) { applyVolume(); });
+    QObject::connect(slider, &QSlider::sliderPressed, widget, [this, pipewireId, slider, muteButton]() {
+        if (pipewireId == 0) {
+            return;
+        }
+        bool ok = false;
+        const int pressValue = slider->property("pressValue").toInt(&ok);
+        const float volume = ok ? (static_cast<float>(pressValue) / 100.0f)
+                                : static_cast<float>(slider->value()) / 100.0f;
+        const bool mute = muteButton->isChecked();
+        m_inlineStartState.insert(pipewireId, NodeVolumeState{volume, mute});
+    });
+    QObject::connect(slider, &QSlider::sliderReleased, widget, [this, pipewireId, slider, muteButton]() {
+        if (pipewireId == 0) {
+            return;
+        }
+        const NodeVolumeState previous = m_inlineStartState.value(pipewireId, m_nodeVolumeState.value(pipewireId));
+        m_inlineStartState.remove(pipewireId);
+        const float volume = static_cast<float>(slider->value()) / 100.0f;
+        const NodeVolumeState next{volume, muteButton->isChecked()};
+        auto *self = const_cast<PipeWireGraphModel*>(this);
+        self->emitNodeVolumeChanged(pipewireId, previous, next);
+    });
+
+    layout->addWidget(muteButton);
+    layout->addWidget(slider);
+
+    widget->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
+    widget->setFixedHeight(26);
+    widget->setStyleSheet(
+        "QToolButton { background: #2b2f38; color: #dbe2ee; border: 1px solid #39404c; border-radius: 4px; font-weight: 700; }"
+        "QToolButton:checked { background: #3c4350; color: #ffcf7a; }"
+        "QSlider::groove:horizontal { height: 4px; background: #2b2f38; border-radius: 2px; }"
+        "QSlider::sub-page:horizontal { background: #5fcf8d; border-radius: 2px; }"
+        "QSlider::add-page:horizontal { background: #2b2f38; border-radius: 2px; }"
+        "QSlider::handle:horizontal { width: 10px; margin: -6px 0; background: #dbe2ee; border-radius: 5px; }"
+    );
+
+    widget->adjustSize();
+
+    m_nodeWidgets.emplace(nodeId, widget);
+    return widget;
+}
+
 QtNodes::NodeId PipeWireGraphModel::newNodeId()
 {
     return m_nextNodeId++;
@@ -210,6 +314,23 @@ bool PipeWireGraphModel::connectionPossible(QtNodes::ConnectionId const connecti
         return false;
     }
 
+    const auto &outPort = outInfo.outputPorts.at(connectionId.outPortIndex);
+    const auto &inPort = inInfo.inputPorts.at(connectionId.inPortIndex);
+    if (outPort.direction != SPA_DIRECTION_OUTPUT || inPort.direction != SPA_DIRECTION_INPUT) {
+        return false;
+    }
+
+    const auto isAudioClass = [](Potato::MediaClass mediaClass) {
+        return mediaClass == Potato::MediaClass::AudioSink
+            || mediaClass == Potato::MediaClass::AudioSource
+            || mediaClass == Potato::MediaClass::AudioDuplex
+            || mediaClass == Potato::MediaClass::Stream;
+    };
+
+    if (!isAudioClass(outInfo.mediaClass) || !isAudioClass(inInfo.mediaClass)) {
+        return false;
+    }
+
     return true;
 }
 
@@ -257,6 +378,10 @@ QVariant PipeWireGraphModel::nodeData(QtNodes::NodeId nodeId, QtNodes::NodeRole
         }
         case QtNodes::NodeRole::Size:
         {
+            auto sizeIt = m_nodeSizes.find(nodeId);
+            if (sizeIt != m_nodeSizes.end()) {
+                return sizeIt->second;
+            }
             const int maxPorts = std::max(info.inputPorts.size(), info.outputPorts.size());
             const int baseHeight = 50;
             const int perPortHeight = 28;
@@ -274,6 +399,8 @@ QVariant PipeWireGraphModel::nodeData(QtNodes::NodeId nodeId, QtNodes::NodeRole
             return QString("PipeWire");
         case QtNodes::NodeRole::Style:
             return nodeStyleVariant(info);
+        case QtNodes::NodeRole::Widget:
+            return QVariant::fromValue(nodeWidget(nodeId));
         default:
             return QVariant();
     }
@@ -293,6 +420,11 @@ bool PipeWireGraphModel::setNodeData(QtNodes::NodeId nodeId, QtNodes::NodeRole r
         return true;
     }
 
+    if (role == QtNodes::NodeRole::Size) {
+        m_nodeSizes[nodeId] = value.toSize();
+        return true;
+    }
+
     return false;
 }
 
@@ -333,9 +465,6 @@ QVariant PipeWireGraphModel::portData(QtNodes::NodeId nodeId,
     }
 
     if (role == QtNodes::PortRole::ConnectionPolicyRole) {
-        if (portType == QtNodes::PortType::In) {
-            return QVariant::fromValue(QtNodes::ConnectionPolicy::One);
-        }
         return QVariant::fromValue(QtNodes::ConnectionPolicy::Many);
     }
 
@@ -379,6 +508,8 @@ bool PipeWireGraphModel::deleteNode(QtNodes::NodeId const nodeId)
 
     m_nodes.erase(nodeId);
     m_positions.erase(nodeId);
+    m_nodeSizes.erase(nodeId);
+    m_nodeWidgets.erase(nodeId);
     Q_EMIT nodeDeleted(nodeId);
     return true;
 }
@@ -476,6 +607,7 @@ bool PipeWireGraphModel::updatePipeWireNode(const Potato::NodeInfo &node)
 
     const QtNodes::NodeId nodeId = it->second;
     m_nodes[nodeId] = node;
+    m_nodeSizes.erase(nodeId);
     Q_EMIT nodeUpdated(nodeId);
     return true;
 }
@@ -503,6 +635,8 @@ void PipeWireGraphModel::reset()
     m_nodes.clear();
     m_pwToNode.clear();
     m_positions.clear();
+    m_nodeSizes.clear();
+    m_nodeWidgets.clear();
     m_nextNodeId = 1;
     Q_EMIT modelReset();
 }
@@ -597,6 +731,168 @@ void PipeWireGraphModel::loadLayout()
     }
 }
 
+QJsonObject PipeWireGraphModel::layoutJson() const
+{
+    QJsonObject root;
+    QJsonArray nodes;
+    for (auto it = m_layoutByStableId.cbegin(); it != m_layoutByStableId.cend(); ++it) {
+        QJsonObject item;
+        item["id"] = it.key();
+        item["x"] = it.value().x();
+        item["y"] = it.value().y();
+        nodes.append(item);
+    }
+    root["nodes"] = nodes;
+
+    QJsonObject view;
+    view["scale"] = m_viewScale;
+    view["center_x"] = m_viewCenter.x();
+    view["center_y"] = m_viewCenter.y();
+    root["view"] = view;
+
+    if (m_hasSplitterSizes && !m_splitterSizes.isEmpty()) {
+        QJsonArray splitter;
+        for (const auto size : m_splitterSizes) {
+            splitter.append(size);
+        }
+        root["splitter"] = splitter;
+    }
+
+    return root;
+}
+
+void PipeWireGraphModel::applyLayoutJson(const QJsonObject &root)
+{
+    m_layoutByStableId.clear();
+    m_hasViewState = false;
+    m_hasSplitterSizes = false;
+    m_splitterSizes.clear();
+
+    const QJsonArray nodes = root.value("nodes").toArray();
+    applyLayoutData(nodes);
+
+    const QJsonObject view = root.value("view").toObject();
+    if (!view.isEmpty()) {
+        m_viewScale = view.value("scale").toDouble(1.0);
+        const double x = view.value("center_x").toDouble(0.0);
+        const double y = view.value("center_y").toDouble(0.0);
+        m_viewCenter = QPointF(x, y);
+        m_hasViewState = true;
+    }
+
+    const QJsonArray splitter = root.value("splitter").toArray();
+    if (!splitter.isEmpty()) {
+        QList<int> sizes;
+        sizes.reserve(splitter.size());
+        for (const auto &value : splitter) {
+            sizes.append(value.toInt());
+        }
+        if (!sizes.isEmpty()) {
+            m_splitterSizes = sizes;
+            m_hasSplitterSizes = true;
+        }
+    }
+
+    for (const auto &entry : m_nodes) {
+        const QtNodes::NodeId nodeId = entry.first;
+        const Potato::NodeInfo &info = entry.second;
+        if (!info.stableId.isEmpty() && m_layoutByStableId.contains(info.stableId)) {
+            const QPointF position = m_layoutByStableId.value(info.stableId);
+            m_positions[nodeId] = position;
+            Q_EMIT nodePositionUpdated(nodeId);
+        }
+    }
+}
+
+QHash<QString, NodeVolumeState> PipeWireGraphModel::volumeStates() const
+{
+    QHash<QString, NodeVolumeState> result;
+    for (const auto &entry : m_nodes) {
+        const Potato::NodeInfo &info = entry.second;
+        if (info.stableId.isEmpty()) {
+            continue;
+        }
+        if (!m_nodeVolumeState.contains(info.id)) {
+            continue;
+        }
+        result.insert(info.stableId, m_nodeVolumeState.value(info.id));
+    }
+    return result;
+}
+
+void PipeWireGraphModel::applyVolumeStates(const QHash<QString, NodeVolumeState> &states)
+{
+    if (!m_controller) {
+        return;
+    }
+
+    const QVector<Potato::NodeInfo> nodes = m_controller->nodes();
+    for (const auto &node : nodes) {
+        if (node.stableId.isEmpty() || !states.contains(node.stableId)) {
+            continue;
+        }
+        const NodeVolumeState state = states.value(node.stableId);
+        setNodeVolumeState(node.id, state, false);
+        m_controller->setNodeVolume(node.id, state.volume, state.mute);
+    }
+}
+
+void PipeWireGraphModel::emitNodeVolumeChanged(uint32_t nodeId, const NodeVolumeState &previous, const NodeVolumeState &current)
+{
+    const bool changedVolume = qAbs(previous.volume - current.volume) > 0.0001f;
+    if (!changedVolume && previous.mute == current.mute) {
+        return;
+    }
+    Q_EMIT nodeVolumeChanged(nodeId, previous, current);
+}
+
+void PipeWireGraphModel::setNodeVolumeState(uint32_t nodeId, const NodeVolumeState &state, bool notify)
+{
+    const NodeVolumeState previous = m_nodeVolumeState.value(nodeId, NodeVolumeState{});
+    m_nodeVolumeState.insert(nodeId, state);
+
+    auto nodeIt = m_pwToNode.find(nodeId);
+    if (nodeIt == m_pwToNode.end()) {
+        return;
+    }
+    auto widgetIt = m_nodeWidgets.find(nodeIt->second);
+    if (widgetIt == m_nodeWidgets.end()) {
+        return;
+    }
+
+    QWidget *widget = widgetIt->second;
+    if (!widget) {
+        return;
+    }
+
+    if (auto *slider = widget->findChild<QSlider*>()) {
+        slider->blockSignals(true);
+        slider->setValue(static_cast<int>(state.volume * 100.0f));
+        slider->blockSignals(false);
+    }
+    if (auto *button = widget->findChild<QToolButton*>()) {
+        button->blockSignals(true);
+        button->setChecked(state.mute);
+        button->blockSignals(false);
+    }
+
+    if (notify) {
+        const bool changedVolume = std::abs(previous.volume - state.volume) > 0.0001f;
+        if (changedVolume || previous.mute != state.mute) {
+            Q_EMIT nodeVolumeChanged(nodeId, previous, state);
+        }
+    }
+}
+
+bool PipeWireGraphModel::nodeVolumeState(uint32_t nodeId, NodeVolumeState &state) const
+{
+    if (!m_nodeVolumeState.contains(nodeId)) {
+        return false;
+    }
+    state = m_nodeVolumeState.value(nodeId);
+    return true;
+}
+
 void PipeWireGraphModel::saveLayout() const
 {
     const QString path = layoutFilePath();

src/gui/PipeWireGraphModel.h

@@ -16,6 +16,13 @@
 #include <unordered_map>
 #include <unordered_set>
 
+class QWidget;
+
+struct NodeVolumeState {
+    float volume = 1.0f;
+    bool mute = false;
+};
+
 class PipeWireGraphModel : public QtNodes::AbstractGraphModel
 {
     Q_OBJECT
@@ -70,8 +77,19 @@ public:
     bool viewState(double &scale, QPointF &center) const;
     void setSplitterSizes(const QList<int> &sizes);
     bool splitterSizes(QList<int> &sizes) const;
+    QJsonObject layoutJson() const;
+    void applyLayoutJson(const QJsonObject &root);
+    QHash<QString, NodeVolumeState> volumeStates() const;
+    void applyVolumeStates(const QHash<QString, NodeVolumeState> &states);
+    void setNodeVolumeState(uint32_t nodeId, const NodeVolumeState &state, bool notify = true);
+    bool nodeVolumeState(uint32_t nodeId, NodeVolumeState &state) const;
+
+signals:
+    void nodeVolumeChanged(uint32_t nodeId, const NodeVolumeState &previous, const NodeVolumeState &current);
 
 private:
+    QWidget *nodeWidget(QtNodes::NodeId nodeId) const;
+    void emitNodeVolumeChanged(uint32_t nodeId, const NodeVolumeState &previous, const NodeVolumeState &current);
     QtNodes::ConnectionId connectionFromPipeWire(const Potato::LinkInfo &link, bool *ok) const;
     bool findPortIndex(const Potato::NodeInfo &node, uint32_t portId, QtNodes::PortType type, QtNodes::PortIndex &index) const;
     QString portLabel(const Potato::PortInfo &port) const;
@@ -95,4 +113,8 @@ private:
     bool m_hasViewState = false;
     QList<int> m_splitterSizes;
     bool m_hasSplitterSizes = false;
+    mutable std::unordered_map<QtNodes::NodeId, QWidget*> m_nodeWidgets;
+    std::unordered_map<QtNodes::NodeId, QSize> m_nodeSizes;
+    mutable QHash<uint32_t, NodeVolumeState> m_nodeVolumeState;
+    mutable QHash<uint32_t, NodeVolumeState> m_inlineStartState;
 };

src/pipewire/pipewirecontroller.cpp

@@ -5,6 +5,7 @@
 #include <QString>
 #include <QElapsedTimer>
 #include <QThread>
+#include <algorithm>
 #include <cstring>
 #include <cstdlib>
 #include <cmath>
@@ -13,14 +14,119 @@
 #include <pipewire/keys.h>
 #include <pipewire/properties.h>
 #include <pipewire/stream.h>
+#include <pipewire/node.h>
 #include <spa/param/props.h>
 #include <spa/param/audio/format-utils.h>
 #include <spa/param/audio/raw.h>
 #include <spa/utils/dict.h>
+#include <spa/utils/defs.h>
 #include <spa/utils/type-info.h>
 
 namespace Potato {
 
+static constexpr uint32_t kMeterRingCapacityBytes = 4096;
+
+static void writeRingValue(spa_ringbuffer *ring, std::vector<uint8_t> &buffer, float value)
+{
+    if (!ring || buffer.empty()) {
+        return;
+    }
+
+    uint32_t index = 0;
+    const uint32_t avail = spa_ringbuffer_get_write_index(ring, &index);
+    if (avail < sizeof(float)) {
+        return;
+    }
+
+    const uint32_t size = static_cast<uint32_t>(buffer.size());
+    uint32_t offset = index & (size - 1);
+    if (offset + sizeof(float) <= size) {
+        std::memcpy(buffer.data() + offset, &value, sizeof(float));
+    } else {
+        const uint32_t first = size - offset;
+        std::memcpy(buffer.data() + offset, &value, first);
+        std::memcpy(buffer.data(), reinterpret_cast<const uint8_t*>(&value) + first, sizeof(float) - first);
+    }
+    spa_ringbuffer_write_update(ring, index + sizeof(float));
+}
+
+static bool readRingLatest(spa_ringbuffer *ring, std::vector<uint8_t> &buffer, float &value)
+{
+    if (!ring || buffer.empty()) {
+        return false;
+    }
+
+    uint32_t index = 0;
+    const uint32_t avail = spa_ringbuffer_get_read_index(ring, &index);
+    if (avail < sizeof(float)) {
+        return false;
+    }
+
+    const uint32_t size = static_cast<uint32_t>(buffer.size());
+    const uint32_t latestIndex = index + (avail - sizeof(float));
+    uint32_t offset = latestIndex & (size - 1);
+    if (offset + sizeof(float) <= size) {
+        std::memcpy(&value, buffer.data() + offset, sizeof(float));
+    } else {
+        const uint32_t first = size - offset;
+        std::memcpy(&value, buffer.data() + offset, first);
+        std::memcpy(reinterpret_cast<uint8_t*>(&value) + first, buffer.data(), sizeof(float) - first);
+    }
+
+    spa_ringbuffer_read_update(ring, index + avail);
+    return true;
+}
+
+bool PipeWireController::createVirtualDevice(const QString &name,
+                                             const QString &description,
+                                             const char *factoryName,
+                                             const char *mediaClass,
+                                             int channels,
+                                             int rate)
+{
+    if (!m_threadLoop || !m_core || name.isEmpty()) {
+        return false;
+    }
+
+    channels = channels > 0 ? channels : 2;
+    rate = rate > 0 ? rate : 48000;
+
+    const QByteArray nameBytes = name.toUtf8();
+    const QByteArray descBytes = description.isEmpty() ? nameBytes : description.toUtf8();
+    const QByteArray channelsBytes = QByteArray::number(channels);
+    const QByteArray rateBytes = QByteArray::number(rate);
+
+    struct spa_dict_item items[] = {
+        { PW_KEY_FACTORY_NAME, factoryName },
+        { PW_KEY_NODE_NAME, nameBytes.constData() },
+        { PW_KEY_NODE_DESCRIPTION, descBytes.constData() },
+        { PW_KEY_MEDIA_CLASS, mediaClass },
+        { PW_KEY_AUDIO_CHANNELS, channelsBytes.constData() },
+        { PW_KEY_AUDIO_RATE, rateBytes.constData() },
+        { "object.linger", "true" },
+        { PW_KEY_APP_NAME, "Potato-Manager" }
+    };
+
+    struct spa_dict dict = SPA_DICT_INIT(items, SPA_N_ELEMENTS(items));
+
+    lock();
+    auto *proxy = static_cast<struct pw_proxy*>(pw_core_create_object(
+        m_core,
+        "adapter",
+        PW_TYPE_INTERFACE_Node,
+        PW_VERSION_NODE,
+        &dict,
+        0));
+    unlock();
+
+    if (!proxy) {
+        return false;
+    }
+
+    m_virtualDevices.push_back(proxy);
+    return true;
+}
+
 static QString toQString(const char *value)
 {
     if (!value) {
@@ -50,7 +156,7 @@ void registryEventGlobal(void *data, uint32_t id, uint32_t permissions,
 void registryEventGlobalRemove(void *data, uint32_t id)
 {
     auto *self = static_cast<PipeWireController*>(data);
-    
+
     {
         QMutexLocker lock(&self->m_nodesMutex);
         if (self->m_nodes.contains(id)) {
@@ -58,18 +164,27 @@ void registryEventGlobalRemove(void *data, uint32_t id)
             emit self->nodeRemoved(id);
             return;
         }
-        
+
         if (self->m_ports.contains(id)) {
             self->m_ports.remove(id);
             return;
         }
-        
+    }
+
+    bool linkRemoved = false;
+    {
+        QMutexLocker lock(&self->m_nodesMutex);
         if (self->m_links.contains(id)) {
             self->m_links.remove(id);
-            emit self->linkRemoved(id);
-            return;
+            linkRemoved = true;
         }
     }
+
+    if (linkRemoved) {
+        emit self->linkRemoved(id);
+        self->handleLinkRemoval(id);
+        return;
+    }
 }
 
 void coreEventDone(void *data, uint32_t id, int seq)
@@ -150,6 +265,9 @@ void meterProcess(void *data)
     }
 
     self->m_meterPeak.store(peak, std::memory_order_relaxed);
+    if (self->m_meterRingReady.load(std::memory_order_relaxed)) {
+        writeRingValue(&self->m_meterRing, self->m_meterRingData, peak);
+    }
     pw_stream_queue_buffer(self->m_meterStream, buf);
 }
 
@@ -217,6 +335,9 @@ PipeWireController::PipeWireController(QObject *parent)
 {
     m_registryListener = new spa_hook;
     m_coreListener = new spa_hook;
+    m_meterRingData.resize(kMeterRingCapacityBytes);
+    spa_ringbuffer_init(&m_meterRing);
+    m_meterRingReady.store(true, std::memory_order_relaxed);
 }
 
 PipeWireController::~PipeWireController()
@@ -321,6 +442,13 @@ void PipeWireController::shutdown()
         }
         m_nodeMeters.clear();
     }
+
+    for (auto *proxy : m_virtualDevices) {
+        if (proxy) {
+            pw_proxy_destroy(proxy);
+        }
+    }
+    m_virtualDevices.clear();
     
     if (m_core) {
         pw_core_disconnect(m_core);
@@ -340,6 +468,9 @@ void PipeWireController::shutdown()
     }
     
     pw_deinit();
+
+    m_meterRingReady.store(false, std::memory_order_relaxed);
+    m_meterRingData.clear();
     
     m_initialized.storeRelaxed(false);
     m_connected.storeRelaxed(false);
@@ -372,7 +503,58 @@ QVector<LinkInfo> PipeWireController::links() const
 
 float PipeWireController::meterPeak() const
 {
-    return m_meterPeak.load(std::memory_order_relaxed);
+    float peak = m_meterPeak.load(std::memory_order_relaxed);
+    if (m_meterRingReady.load(std::memory_order_relaxed)) {
+        float ringPeak = 0.0f;
+        if (readRingLatest(&m_meterRing, m_meterRingData, ringPeak)) {
+            peak = ringPeak;
+        }
+    }
+    return peak;
+}
+
+bool PipeWireController::setNodeVolume(uint32_t nodeId, float volume, bool mute)
+{
+    if (!m_threadLoop || !m_core || !m_registry) {
+        return false;
+    }
+
+    if (nodeId == 0) {
+        return false;
+    }
+
+    volume = std::clamp(volume, 0.0f, 1.0f);
+
+    lock();
+    auto *node = static_cast<struct pw_node*>(
+        pw_registry_bind(m_registry, nodeId, PW_TYPE_INTERFACE_Node, PW_VERSION_NODE, 0));
+    if (!node) {
+        unlock();
+        return false;
+    }
+
+    uint8_t buffer[128];
+    spa_pod_builder builder = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));
+    auto *param = reinterpret_cast<const struct spa_pod*>(spa_pod_builder_add_object(
+        &builder,
+        SPA_TYPE_OBJECT_Props, SPA_PARAM_Props,
+        SPA_PROP_volume, SPA_POD_Float(volume),
+        SPA_PROP_mute, SPA_POD_Bool(mute)));
+
+    pw_node_set_param(node, SPA_PARAM_Props, 0, param);
+    pw_proxy_destroy(reinterpret_cast<struct pw_proxy*>(node));
+    unlock();
+    return true;
+}
+
+bool PipeWireController::createVirtualSink(const QString &name, const QString &description, int channels, int rate)
+{
+    return createVirtualDevice(name, description, "support.null-audio-sink", "Audio/Sink", channels, rate);
+}
+
+bool PipeWireController::createVirtualSource(const QString &name, const QString &description, int channels, int rate)
+{
+    return createVirtualDevice(name, description, "support.null-audio-sink", "Audio/Source", channels, rate);
 }
 
 float PipeWireController::nodeMeterPeak(uint32_t nodeId) const
@@ -596,6 +778,11 @@ bool PipeWireController::destroyLink(uint32_t linkId)
             return false;
         }
         linkInfo = m_links.value(linkId);
+        m_userRemovedLinks.insert(linkId);
+        if (m_linkIntentKeys.contains(linkId)) {
+            const QString key = m_linkIntentKeys.take(linkId);
+            m_linkIntents.remove(key);
+        }
     }
     
     lock();
@@ -609,21 +796,156 @@ bool PipeWireController::destroyLink(uint32_t linkId)
     
     unlock();
     
-    QElapsedTimer timer;
-    timer.start();
-    while (timer.elapsed() < 2000) {
-        {
-            QMutexLocker lock(&m_nodesMutex);
-            if (!m_links.contains(linkId)) {
-                qInfo() << "Link destroyed:" << linkId;
-                return true;
-            }
-        }
-        QThread::msleep(10);
+    qInfo() << "Link destroy requested:" << linkId;
+    return true;
+}
+
+void PipeWireController::rememberLinkIntent(const LinkInfo &link)
+{
+    QString key;
+    if (!buildLinkIntentKey(link, key)) {
+        return;
     }
 
-    qWarning() << "Link destroy requested but ID still present" << linkId;
-    return false;
+    QMutexLocker lock(&m_nodesMutex);
+    m_linkIntents.insert(key);
+    m_linkIntentKeys.insert(link.id, key);
+}
+
+void PipeWireController::handleLinkRemoval(uint32_t linkId)
+{
+    QMutexLocker lock(&m_nodesMutex);
+    if (m_userRemovedLinks.contains(linkId)) {
+        m_userRemovedLinks.remove(linkId);
+    }
+    if (m_linkIntentKeys.contains(linkId)) {
+        m_linkIntentKeys.remove(linkId);
+    }
+}
+
+void PipeWireController::tryRestoreLinks()
+{
+    QList<QString> intents;
+    {
+        QMutexLocker lock(&m_nodesMutex);
+        intents = m_linkIntents.values();
+    }
+
+    for (const auto &key : intents) {
+        uint32_t outNodeId = 0;
+        uint32_t outPortId = 0;
+        uint32_t inNodeId = 0;
+        uint32_t inPortId = 0;
+        if (!resolveLinkIntentKey(key, outNodeId, outPortId, inNodeId, inPortId)) {
+            continue;
+        }
+        createLink(outNodeId, outPortId, inNodeId, inPortId);
+    }
+}
+
+void PipeWireController::updateLinkIntentsForNode(uint32_t nodeId)
+{
+    QVector<LinkInfo> links;
+    {
+        QMutexLocker lock(&m_nodesMutex);
+        for (auto it = m_links.cbegin(); it != m_links.cend(); ++it) {
+            const LinkInfo &link = it.value();
+            if (link.outputNodeId == nodeId || link.inputNodeId == nodeId) {
+                links.append(link);
+            }
+        }
+    }
+
+    for (const auto &link : links) {
+        rememberLinkIntent(link);
+    }
+}
+
+static bool isMeterNodeName(const QString &name)
+{
+    return name.startsWith("Potato-Meter") || name.startsWith("Potato-Node-Meter");
+}
+
+bool PipeWireController::buildLinkIntentKey(const LinkInfo &link, QString &key) const
+{
+    QMutexLocker lock(&m_nodesMutex);
+    if (!m_nodes.contains(link.outputNodeId) || !m_nodes.contains(link.inputNodeId)) {
+        return false;
+    }
+
+    const NodeInfo &outNode = m_nodes.value(link.outputNodeId);
+    const NodeInfo &inNode = m_nodes.value(link.inputNodeId);
+    if (isMeterNodeName(outNode.name) || isMeterNodeName(inNode.name)) {
+        return false;
+    }
+
+    QString outPortName;
+    QString inPortName;
+    for (const auto &port : outNode.outputPorts) {
+        if (port.id == link.outputPortId) {
+            outPortName = port.name;
+            break;
+        }
+    }
+    for (const auto &port : inNode.inputPorts) {
+        if (port.id == link.inputPortId) {
+            inPortName = port.name;
+            break;
+        }
+    }
+    if (outPortName.isEmpty() || inPortName.isEmpty()) {
+        return false;
+    }
+    if (outNode.stableId.isEmpty() || inNode.stableId.isEmpty()) {
+        return false;
+    }
+
+    key = QString("%1||%2>>%3||%4").arg(outNode.stableId, outPortName, inNode.stableId, inPortName);
+    return true;
+}
+
+bool PipeWireController::resolveLinkIntentKey(const QString &key, uint32_t &outNodeId, uint32_t &outPortId,
+                                              uint32_t &inNodeId, uint32_t &inPortId) const
+{
+    const QStringList halves = key.split(">>");
+    if (halves.size() != 2) {
+        return false;
+    }
+    const QStringList outParts = halves.at(0).split("||");
+    const QStringList inParts = halves.at(1).split("||");
+    if (outParts.size() != 2 || inParts.size() != 2) {
+        return false;
+    }
+
+    const QString outStableId = outParts.at(0);
+    const QString outPortName = outParts.at(1);
+    const QString inStableId = inParts.at(0);
+    const QString inPortName = inParts.at(1);
+
+    QMutexLocker lock(&m_nodesMutex);
+    for (const auto &nodeEntry : m_nodes) {
+        const NodeInfo &node = nodeEntry;
+        if (node.stableId == outStableId) {
+            for (const auto &port : node.outputPorts) {
+                if (port.name == outPortName) {
+                    outNodeId = node.id;
+                    outPortId = port.id;
+                    break;
+                }
+            }
+        }
+        if (node.stableId == inStableId) {
+            for (const auto &port : node.inputPorts) {
+                if (port.name == inPortName) {
+                    inNodeId = node.id;
+                    inPortId = port.id;
+                    break;
+                }
+            }
+        }
+    }
+
+    return outNodeId != 0 && outPortId != 0 && inNodeId != 0 && inPortId != 0;
 }
 
 QString PipeWireController::dumpGraph() const
@@ -710,6 +1032,9 @@ void PipeWireController::handleNodeInfo(uint32_t id, const struct spa_dict *prop
             qDebug() << "Node changed:" << node.id << node.name;
         }
     }
+
+    updateLinkIntentsForNode(id);
+    tryRestoreLinks();
 }
 
 void PipeWireController::handlePortInfo(uint32_t id, const struct spa_dict *props)
@@ -737,10 +1062,12 @@ void PipeWireController::handlePortInfo(uint32_t id, const struct spa_dict *prop
     uint32_t nodeId = nodeIdStr ? static_cast<uint32_t>(atoi(nodeIdStr)) : 0;
     PortInfo port(id, nodeId, portName, direction);
     
+    bool emitChanged = false;
+    NodeInfo nodeSnapshot;
     {
         QMutexLocker lock(&m_nodesMutex);
         m_ports.insert(id, port);
-        
+
         if (nodeId != 0 && m_nodes.contains(nodeId)) {
             NodeInfo &node = m_nodes[nodeId];
             auto &ports = (direction == PW_DIRECTION_INPUT) ? node.inputPorts : node.outputPorts;
@@ -751,9 +1078,18 @@ void PipeWireController::handlePortInfo(uint32_t id, const struct spa_dict *prop
                 }
             }
             ports.append(port);
+            nodeSnapshot = node;
+            emitChanged = true;
         }
     }
-    
+
+    if (emitChanged) {
+        emit nodeChanged(nodeSnapshot);
+    }
+
+    updateLinkIntentsForNode(nodeId);
+    tryRestoreLinks();
+
     qDebug() << "Port added:" << id << portName << "direction:" << direction;
 }
 
@@ -781,6 +1117,8 @@ void PipeWireController::handleLinkInfo(uint32_t id, const struct spa_dict *prop
     }
     
     emit linkAdded(link);
+
+    rememberLinkIntent(link);
     
     qDebug() << "Link added:" << id << "from" << outputNode << ":" << outputPort 
              << "to" << inputNode << ":" << inputPort;

src/pipewire/pipewirecontroller.h

@@ -5,13 +5,19 @@
 #include <QMap>
 #include <QMutex>
 #include <QAtomicInteger>
+#include <QHash>
+#include <QSet>
 #include <atomic>
+#include <vector>
+
+#include <spa/utils/ringbuffer.h>
 
 struct pw_thread_loop;
 struct pw_context;
 struct pw_core;
 struct pw_registry;
 struct pw_stream;
+struct pw_proxy;
 struct spa_hook;
 struct spa_dict;
 namespace Potato {
@@ -38,6 +44,9 @@ public:
     float nodeMeterPeak(uint32_t nodeId) const;
     void ensureNodeMeter(uint32_t nodeId, const QString &targetName, bool captureSink);
     void removeNodeMeter(uint32_t nodeId);
+    bool setNodeVolume(uint32_t nodeId, float volume, bool mute);
+    bool createVirtualSink(const QString &name, const QString &description, int channels, int rate);
+    bool createVirtualSource(const QString &name, const QString &description, int channels, int rate);
     
     uint32_t createLink(uint32_t outputNodeId, uint32_t outputPortId,
                         uint32_t inputNodeId, uint32_t inputPortId);
@@ -72,6 +81,16 @@ private:
     void handleLinkInfo(uint32_t id, const struct ::spa_dict *props);
     bool setupMeterStream();
     void teardownMeterStream();
+    bool createVirtualDevice(const QString &name, const QString &description,
+                             const char *factoryName, const char *mediaClass,
+                             int channels, int rate);
+    void rememberLinkIntent(const LinkInfo &link);
+    void handleLinkRemoval(uint32_t linkId);
+    void tryRestoreLinks();
+    void updateLinkIntentsForNode(uint32_t nodeId);
+    bool buildLinkIntentKey(const LinkInfo &link, QString &key) const;
+    bool resolveLinkIntentKey(const QString &key, uint32_t &outNodeId, uint32_t &outPortId,
+                              uint32_t &inNodeId, uint32_t &inPortId) const;
     
     void lock();
     void unlock();
@@ -89,10 +108,18 @@ private:
     QMap<uint32_t, NodeInfo> m_nodes;
     QMap<uint32_t, PortInfo> m_ports;
     QMap<uint32_t, LinkInfo> m_links;
+    QSet<QString> m_linkIntents;
+    QHash<uint32_t, QString> m_linkIntentKeys;
+    QSet<uint32_t> m_userRemovedLinks;
     
     QAtomicInteger<bool> m_connected{false};
     QAtomicInteger<bool> m_initialized{false};
     std::atomic<float> m_meterPeak{0.0f};
+    mutable spa_ringbuffer m_meterRing{};
+    mutable std::vector<uint8_t> m_meterRingData;
+    std::atomic<bool> m_meterRingReady{false};
+
+    std::vector<struct pw_proxy*> m_virtualDevices;
 
     mutable QMutex m_meterMutex;
     QMap<uint32_t, NodeMeter*> m_nodeMeters;

src/presets/PresetManager.cpp

@@ -0,0 +1,293 @@
+#include "presets/PresetManager.h"
+
+#include "pipewire/pipewirecontroller.h"
+#include "gui/PipeWireGraphModel.h"
+
+#include <QFile>
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QVector>
+
+#include <algorithm>
+
+PresetManager::PresetManager(Potato::PipeWireController *controller,
+                             PipeWireGraphModel *model,
+                             QObject *parent)
+    : QObject(parent)
+    , m_controller(controller)
+    , m_model(model)
+{
+}
+
+bool PresetManager::savePreset(const QString &path) const
+{
+    if (!m_controller || !m_model || path.isEmpty()) {
+        return false;
+    }
+
+    const QJsonObject root = buildPreset();
+    const QJsonDocument doc(root);
+
+    QFile file(path);
+    if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
+        return false;
+    }
+
+    file.write(doc.toJson(QJsonDocument::Indented));
+    return true;
+}
+
+bool PresetManager::loadPreset(const QString &path)
+{
+    if (!m_controller || !m_model || path.isEmpty()) {
+        return false;
+    }
+
+    QFile file(path);
+    if (!file.open(QIODevice::ReadOnly)) {
+        return false;
+    }
+
+    const QJsonDocument doc = QJsonDocument::fromJson(file.readAll());
+    if (!doc.isObject()) {
+        return false;
+    }
+
+    return applyPreset(doc.object());
+}
+
+QJsonObject PresetManager::buildPreset() const
+{
+    QJsonObject root;
+    root["version"] = QString("1.0");
+
+    const QVector<Potato::NodeInfo> nodes = m_controller->nodes();
+    QHash<uint32_t, Potato::NodeInfo> nodesById;
+    for (const auto &node : nodes) {
+        nodesById.insert(node.id, node);
+    }
+
+    QJsonArray virtualDevices;
+    for (const auto &node : nodes) {
+        if (node.type != Potato::NodeType::Virtual) {
+            continue;
+        }
+        QJsonObject device;
+        device["name"] = node.name;
+        device["description"] = node.description;
+        device["stable_id"] = node.stableId;
+        const int channels = std::max(node.inputPorts.size(), node.outputPorts.size());
+        device["channels"] = channels > 0 ? channels : 2;
+        device["rate"] = 48000;
+        device["media_class"] = mediaClassToString(node.mediaClass);
+        virtualDevices.append(device);
+    }
+    root["virtual_devices"] = virtualDevices;
+
+    QJsonArray routing;
+    const QVector<Potato::LinkInfo> links = m_controller->links();
+    for (const auto &link : links) {
+        if (!nodesById.contains(link.outputNodeId) || !nodesById.contains(link.inputNodeId)) {
+            continue;
+        }
+        const Potato::NodeInfo &outNode = nodesById.value(link.outputNodeId);
+        const Potato::NodeInfo &inNode = nodesById.value(link.inputNodeId);
+
+        QString outPortName;
+        QString inPortName;
+        if (!findPortName(outNode, link.outputPortId, outPortName)) {
+            continue;
+        }
+        if (!findPortName(inNode, link.inputPortId, inPortName)) {
+            continue;
+        }
+
+        QJsonObject route;
+        route["source"] = QString("%1:%2").arg(outNode.stableId, outPortName);
+        route["target"] = QString("%1:%2").arg(inNode.stableId, inPortName);
+        route["volume"] = 1.0;
+        route["muted"] = false;
+        routing.append(route);
+    }
+    root["routing"] = routing;
+
+    QJsonObject volumes;
+    QJsonObject mutes;
+    const QHash<QString, NodeVolumeState> volumeStates = m_model->volumeStates();
+    for (auto it = volumeStates.cbegin(); it != volumeStates.cend(); ++it) {
+        volumes[it.key()] = it.value().volume;
+        mutes[it.key()] = it.value().mute;
+    }
+    root["persistent_volumes"] = volumes;
+    root["persistent_mutes"] = mutes;
+
+    root["ui_layout"] = m_model->layoutJson();
+
+    return root;
+}
+
+bool PresetManager::applyPreset(const QJsonObject &root)
+{
+    const QVector<Potato::NodeInfo> nodes = m_controller->nodes();
+    QHash<QString, Potato::NodeInfo> nodesByStableId;
+    for (const auto &node : nodes) {
+        if (!node.stableId.isEmpty()) {
+            nodesByStableId.insert(node.stableId, node);
+        }
+    }
+
+    const QJsonArray virtualDevices = root.value("virtual_devices").toArray();
+    for (const auto &entry : virtualDevices) {
+        const QJsonObject device = entry.toObject();
+        const QString stableId = device.value("stable_id").toString();
+        const QString name = device.value("name").toString();
+        const QString description = device.value("description").toString();
+        const QString mediaClassValue = device.value("media_class").toString();
+        const int channels = device.value("channels").toInt(2);
+        const int rate = device.value("rate").toInt(48000);
+
+        if (!stableId.isEmpty() && nodesByStableId.contains(stableId)) {
+            continue;
+        }
+
+        const Potato::MediaClass mediaClass = mediaClassFromString(mediaClassValue);
+        if (mediaClass == Potato::MediaClass::AudioSource) {
+            m_controller->createVirtualSource(name, description, channels, rate);
+        } else {
+            m_controller->createVirtualSink(name, description, channels, rate);
+        }
+    }
+
+    const QJsonArray routing = root.value("routing").toArray();
+    for (const auto &entry : routing) {
+        const QJsonObject route = entry.toObject();
+        const QString source = route.value("source").toString();
+        const QString target = route.value("target").toString();
+
+        uint32_t outNodeId = 0;
+        uint32_t outPortId = 0;
+        uint32_t inNodeId = 0;
+        uint32_t inPortId = 0;
+
+        if (!parsePortKey(source, outNodeId, outPortId)) {
+            continue;
+        }
+        if (!parsePortKey(target, inNodeId, inPortId)) {
+            continue;
+        }
+
+        m_controller->createLink(outNodeId, outPortId, inNodeId, inPortId);
+    }
+
+    QHash<QString, NodeVolumeState> volumeStates;
+    const QJsonObject volumes = root.value("persistent_volumes").toObject();
+    const QJsonObject mutes = root.value("persistent_mutes").toObject();
+    for (auto it = volumes.begin(); it != volumes.end(); ++it) {
+        NodeVolumeState state;
+        state.volume = static_cast<float>(it.value().toDouble(1.0));
+        state.mute = mutes.value(it.key()).toBool(false);
+        volumeStates.insert(it.key(), state);
+    }
+    if (!volumeStates.isEmpty()) {
+        m_model->applyVolumeStates(volumeStates);
+    }
+
+    const QJsonObject layout = root.value("ui_layout").toObject();
+    if (!layout.isEmpty()) {
+        m_model->applyLayoutJson(layout);
+    }
+
+    return true;
+}
+
+bool PresetManager::findPortName(const Potato::NodeInfo &node, uint32_t portId, QString &portName) const
+{
+    for (const auto &port : node.inputPorts) {
+        if (port.id == portId) {
+            portName = port.name;
+            return true;
+        }
+    }
+    for (const auto &port : node.outputPorts) {
+        if (port.id == portId) {
+            portName = port.name;
+            return true;
+        }
+    }
+    return false;
+}
+
+bool PresetManager::parsePortKey(const QString &key, uint32_t &nodeId, uint32_t &portId) const
+{
+    const int split = key.lastIndexOf(':');
+    if (split <= 0) {
+        return false;
+    }
+
+    const QString stableId = key.left(split);
+    const QString portName = key.mid(split + 1);
+    if (stableId.isEmpty() || portName.isEmpty()) {
+        return false;
+    }
+
+    const QVector<Potato::NodeInfo> nodes = m_controller->nodes();
+    for (const auto &node : nodes) {
+        if (node.stableId != stableId) {
+            continue;
+        }
+        for (const auto &port : node.inputPorts) {
+            if (port.name == portName) {
+                nodeId = node.id;
+                portId = port.id;
+                return true;
+            }
+        }
+        for (const auto &port : node.outputPorts) {
+            if (port.name == portName) {
+                nodeId = node.id;
+                portId = port.id;
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+QString PresetManager::portKey(const Potato::NodeInfo &node, const Potato::PortInfo &port) const
+{
+    return QString("%1:%2").arg(node.stableId, port.name);
+}
+
+QString PresetManager::mediaClassToString(Potato::MediaClass mediaClass) const
+{
+    switch (mediaClass) {
+    case Potato::MediaClass::AudioSink:
+        return QString("Audio/Sink");
+    case Potato::MediaClass::AudioSource:
+        return QString("Audio/Source");
+    case Potato::MediaClass::AudioDuplex:
+        return QString("Audio/Duplex");
+    case Potato::MediaClass::Stream:
+        return QString("Stream");
+    default:
+        return QString();
+    }
+}
+
+Potato::MediaClass PresetManager::mediaClassFromString(const QString &value) const
+{
+    if (value.contains("Audio/Source")) {
+        return Potato::MediaClass::AudioSource;
+    }
+    if (value.contains("Audio/Duplex")) {
+        return Potato::MediaClass::AudioDuplex;
+    }
+    if (value.contains("Audio/Sink")) {
+        return Potato::MediaClass::AudioSink;
+    }
+    if (value.contains("Stream")) {
+        return Potato::MediaClass::Stream;
+    }
+    return Potato::MediaClass::Unknown;
+}

src/presets/PresetManager.h

@@ -0,0 +1,38 @@
+#pragma once
+
+#include <QObject>
+#include <QHash>
+#include <QJsonObject>
+#include <QString>
+#include <cstdint>
+
+#include "pipewire/nodeinfo.h"
+
+class PipeWireGraphModel;
+
+namespace Potato {
+class PipeWireController;
+}
+
+class PresetManager : public QObject
+{
+public:
+    explicit PresetManager(Potato::PipeWireController *controller,
+                           PipeWireGraphModel *model,
+                           QObject *parent = nullptr);
+
+    bool savePreset(const QString &path) const;
+    bool loadPreset(const QString &path);
+
+private:
+    QJsonObject buildPreset() const;
+    bool applyPreset(const QJsonObject &root);
+    bool findPortName(const Potato::NodeInfo &node, uint32_t portId, QString &portName) const;
+    bool parsePortKey(const QString &key, uint32_t &nodeId, uint32_t &portId) const;
+    QString portKey(const Potato::NodeInfo &node, const Potato::PortInfo &port) const;
+    QString mediaClassToString(Potato::MediaClass mediaClass) const;
+    Potato::MediaClass mediaClassFromString(const QString &value) const;
+
+    Potato::PipeWireController *m_controller = nullptr;
+    PipeWireGraphModel *m_model = nullptr;
+};