Add MCP bridge for external tool integration

Embedded JSON-RPC server over named pipes (rcx-mcp) enabling external
tools like Claude Code to inspect and manipulate the node tree, read/write
hex data, switch sources, and trigger UI actions. Includes stdio adapter
(rcx-mcp-stdio) for stdin/stdout transport. Server is stopped by default;
user starts via File > Start MCP Server.

Also extracts MainWindow class declaration to mainwindow.h and improves
type selector popup Esc button styling.

src/controller.h

@@ -110,6 +110,12 @@ public:
     RcxDocument* document() const { return m_doc; }
     void setEditorFont(const QString& fontName);
 
+    // MCP bridge accessors
+    void setSuppressRefresh(bool v) { m_suppressRefresh = v; }
+    const QVector<SavedSourceEntry>& savedSources() const { return m_savedSources; }
+    int activeSourceIndex() const { return m_activeSourceIdx; }
+    void switchSource(int idx) { switchToSavedSource(idx); }
+
 signals:
     void nodeSelected(int nodeIdx);
     void selectionChanged(int count);

src/main.cpp

@@ -1,6 +1,6 @@
-#include "controller.h"
+#include "mainwindow.h"
 #include "generator.h"
-#include "pluginmanager.h"
+#include "mcp/mcp_bridge.h"
 #include <QApplication>
 #include <QMainWindow>
 #include <QMdiArea>
@@ -170,98 +170,7 @@ static void applyGlobalTheme(const rcx::Theme& theme) {
 
 namespace rcx {
 
-class MainWindow : public QMainWindow {
-    Q_OBJECT
-public:
-    explicit MainWindow(QWidget* parent = nullptr);
-
-private slots:
-    void newFile();
-    void newDocument();
-    void selfTest();
-    void openFile();
-    void saveFile();
-    void saveFileAs();
-
-
-    void addNode();
-    void removeNode();
-    void changeNodeType();
-    void renameNodeAction();
-    void duplicateNodeAction();
-    void splitView();
-    void unsplitView();
-
-    void undo();
-    void redo();
-    void about();
-    void setEditorFont(const QString& fontName);
-    void exportCpp();
-    void showTypeAliasesDialog();
-    void editTheme();
-
-public:
-    // Project Lifecycle API
-    QMdiSubWindow* project_new();
-    QMdiSubWindow* project_open(const QString& path = {});
-    bool project_save(QMdiSubWindow* sub = nullptr, bool saveAs = false);
-    void project_close(QMdiSubWindow* sub = nullptr);
-
-private:
-    enum ViewMode { VM_Reclass, VM_Rendered };
-
-    QMdiArea* m_mdiArea;
-    QLabel*   m_statusLabel;
-    PluginManager m_pluginManager;
-
-    struct SplitPane {
-        QTabWidget*    tabWidget = nullptr;
-        RcxEditor*     editor    = nullptr;
-        QsciScintilla* rendered  = nullptr;
-        ViewMode       viewMode  = VM_Reclass;
-        uint64_t       lastRenderedRootId = 0;
-    };
-
-    struct TabState {
-        RcxDocument*       doc;
-        RcxController*     ctrl;
-        QSplitter*         splitter;
-        QVector<SplitPane> panes;
-        int                activePaneIdx = 0;
-    };
-    QMap<QMdiSubWindow*, TabState> m_tabs;
-
-
-    void createMenus();
-    void createStatusBar();
-    void showPluginsDialog();
-    QIcon makeIcon(const QString& svgPath);
-
-    RcxController* activeController() const;
-    TabState* activeTab();
-    QMdiSubWindow* createTab(RcxDocument* doc);
-    void updateWindowTitle();
-
-    void setViewMode(ViewMode mode);
-    void updateRenderedView(TabState& tab, SplitPane& pane);
-    void updateAllRenderedPanes(TabState& tab);
-    uint64_t findRootStructForNode(const NodeTree& tree, uint64_t nodeId) const;
-    void setupRenderedSci(QsciScintilla* sci);
-
-    SplitPane createSplitPane(TabState& tab);
-    void applyTheme(const Theme& theme);
-    void applyTabWidgetStyle(QTabWidget* tw);
-    SplitPane* findPaneByTabWidget(QTabWidget* tw);
-    SplitPane* findActiveSplitPane();
-    RcxEditor* activePaneEditor();
-
-    // Workspace dock
-    QDockWidget*        m_workspaceDock  = nullptr;
-    QTreeView*          m_workspaceTree  = nullptr;
-    QStandardItemModel* m_workspaceModel = nullptr;
-    void createWorkspaceDock();
-    void rebuildWorkspaceModel();
-};
+// MainWindow class declaration is in mainwindow.h
 
 MainWindow::MainWindow(QWidget* parent) : QMainWindow(parent) {
     setWindowTitle("Reclass");
@@ -300,6 +209,9 @@ MainWindow::MainWindow(QWidget* parent) : QMainWindow(parent) {
     // Load plugins
     m_pluginManager.LoadPlugins();
 
+    // MCP bridge (stopped by default — user starts via File → Start MCP)
+    m_mcp = new McpBridge(this, this);
+
     connect(m_mdiArea, &QMdiArea::subWindowActivated,
             this, [this](QMdiSubWindow*) {
         updateWindowTitle();
@@ -336,6 +248,8 @@ void MainWindow::createMenus() {
     file->addSeparator();
     file->addAction(makeIcon(":/vsicons/export.svg"), "Export &C++ Header...", this, &MainWindow::exportCpp);
     file->addSeparator();
+    m_mcpAction = file->addAction("Start &MCP Server", this, &MainWindow::toggleMcp);
+    file->addSeparator();
     file->addAction(makeIcon(":/vsicons/close.svg"), "E&xit", QKeySequence(Qt::Key_Close), this, &QMainWindow::close);
 
     // Edit
@@ -839,6 +753,18 @@ void MainWindow::about() {
     dlg.exec();
 }
 
+void MainWindow::toggleMcp() {
+    if (m_mcp->isRunning()) {
+        m_mcp->stop();
+        m_mcpAction->setText("Start &MCP Server");
+        m_statusLabel->setText("MCP server stopped");
+    } else {
+        m_mcp->start();
+        m_mcpAction->setText("Stop &MCP Server");
+        m_statusLabel->setText("MCP server listening on pipe: rcx-mcp");
+    }
+}
+
 void MainWindow::applyTheme(const Theme& theme) {
     applyGlobalTheme(theme);
 
@@ -922,6 +848,15 @@ MainWindow::TabState* MainWindow::activeTab() {
     return nullptr;
 }
 
+MainWindow::TabState* MainWindow::tabByIndex(int index) {
+    auto subs = m_mdiArea->subWindowList();
+    if (index < 0 || index >= subs.size()) return nullptr;
+    auto* sub = subs[index];
+    if (m_tabs.contains(sub))
+        return &m_tabs[sub];
+    return nullptr;
+}
+
 void MainWindow::updateWindowTitle() {
     auto* sub = m_mdiArea->activeSubWindow();
     if (sub && m_tabs.contains(sub)) {
@@ -1465,4 +1400,4 @@ int main(int argc, char* argv[]) {
     return app.exec();
 }
 
-#include "main.moc"
+// MainWindow Q_OBJECT is now in mainwindow.h; AUTOMOC handles moc generation.

src/mainwindow.h

@@ -0,0 +1,119 @@
+#pragma once
+#include "controller.h"
+#include "pluginmanager.h"
+#include <QMainWindow>
+#include <QMdiArea>
+#include <QMdiSubWindow>
+#include <QLabel>
+#include <QSplitter>
+#include <QTabWidget>
+#include <QDockWidget>
+#include <QTreeView>
+#include <QStandardItemModel>
+#include <QMap>
+#include <Qsci/qsciscintilla.h>
+
+namespace rcx {
+
+class McpBridge;
+
+class MainWindow : public QMainWindow {
+    Q_OBJECT
+    friend class McpBridge;
+public:
+    explicit MainWindow(QWidget* parent = nullptr);
+
+private slots:
+    void newFile();
+    void newDocument();
+    void selfTest();
+    void openFile();
+    void saveFile();
+    void saveFileAs();
+
+
+    void addNode();
+    void removeNode();
+    void changeNodeType();
+    void renameNodeAction();
+    void duplicateNodeAction();
+    void splitView();
+    void unsplitView();
+
+    void undo();
+    void redo();
+    void about();
+    void toggleMcp();
+    void setEditorFont(const QString& fontName);
+    void exportCpp();
+    void showTypeAliasesDialog();
+    void editTheme();
+
+public:
+    // Project Lifecycle API
+    QMdiSubWindow* project_new();
+    QMdiSubWindow* project_open(const QString& path = {});
+    bool project_save(QMdiSubWindow* sub = nullptr, bool saveAs = false);
+    void project_close(QMdiSubWindow* sub = nullptr);
+
+private:
+    enum ViewMode { VM_Reclass, VM_Rendered };
+
+    QMdiArea* m_mdiArea;
+    QLabel*   m_statusLabel;
+    PluginManager m_pluginManager;
+    McpBridge*    m_mcp       = nullptr;
+    QAction*      m_mcpAction = nullptr;
+
+    struct SplitPane {
+        QTabWidget*    tabWidget = nullptr;
+        RcxEditor*     editor    = nullptr;
+        QsciScintilla* rendered  = nullptr;
+        ViewMode       viewMode  = VM_Reclass;
+        uint64_t       lastRenderedRootId = 0;
+    };
+
+    struct TabState {
+        RcxDocument*       doc;
+        RcxController*     ctrl;
+        QSplitter*         splitter;
+        QVector<SplitPane> panes;
+        int                activePaneIdx = 0;
+    };
+    QMap<QMdiSubWindow*, TabState> m_tabs;
+
+
+    void createMenus();
+    void createStatusBar();
+    void showPluginsDialog();
+    QIcon makeIcon(const QString& svgPath);
+
+    RcxController* activeController() const;
+    TabState* activeTab();
+    TabState* tabByIndex(int index);
+    int tabCount() const { return m_tabs.size(); }
+    QMdiSubWindow* createTab(RcxDocument* doc);
+    void updateWindowTitle();
+
+    void setViewMode(ViewMode mode);
+    void updateRenderedView(TabState& tab, SplitPane& pane);
+    void updateAllRenderedPanes(TabState& tab);
+    uint64_t findRootStructForNode(const NodeTree& tree, uint64_t nodeId) const;
+    void setupRenderedSci(QsciScintilla* sci);
+
+    SplitPane createSplitPane(TabState& tab);
+    void applyTheme(const Theme& theme);
+    void applyTabWidgetStyle(QTabWidget* tw);
+    SplitPane* findPaneByTabWidget(QTabWidget* tw);
+    SplitPane* findActiveSplitPane();
+    RcxEditor* activePaneEditor();
+
+    // Workspace dock
+    QDockWidget*        m_workspaceDock  = nullptr;
+    QTreeView*          m_workspaceTree  = nullptr;
+    QStandardItemModel* m_workspaceModel = nullptr;
+    void createWorkspaceDock();
+    void rebuildWorkspaceModel();
+};
+
+} // namespace rcx

src/mcp/mcp_bridge.h

@@ -0,0 +1,67 @@
+#pragma once
+#include "mainwindow.h"
+#include <QObject>
+#include <QLocalServer>
+#include <QLocalSocket>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QByteArray>
+
+namespace rcx {
+
+class McpBridge : public QObject {
+    Q_OBJECT
+public:
+    explicit McpBridge(MainWindow* mainWindow, QObject* parent = nullptr);
+    ~McpBridge() override;
+
+    void start();
+    void stop();
+    bool isRunning() const { return m_server != nullptr; }
+
+    // Call from controller refresh / data change to notify MCP clients
+    void notifyTreeChanged();
+    void notifyDataChanged();
+
+private:
+    MainWindow*    m_mainWindow;
+    QLocalServer*  m_server    = nullptr;
+    QLocalSocket*  m_client    = nullptr;  // single client for v1
+    QByteArray     m_readBuffer;
+    bool           m_initialized = false;
+
+    // JSON-RPC plumbing
+    void onNewConnection();
+    void onReadyRead();
+    void onDisconnected();
+    void processLine(const QByteArray& line);
+    void sendJson(const QJsonObject& obj);
+    QJsonObject okReply(const QJsonValue& id, const QJsonObject& result);
+    QJsonObject errReply(const QJsonValue& id, int code, const QString& msg);
+    void sendNotification(const QString& method, const QJsonObject& params = {});
+
+    // MCP method handlers
+    QJsonObject handleInitialize(const QJsonValue& id, const QJsonObject& params);
+    QJsonObject handleToolsList(const QJsonValue& id);
+    QJsonObject handleToolsCall(const QJsonValue& id, const QJsonObject& params);
+
+    // Tool implementations
+    QJsonObject toolProjectState(const QJsonObject& args);
+    QJsonObject toolTreeApply(const QJsonObject& args);
+    QJsonObject toolSourceSwitch(const QJsonObject& args);
+    QJsonObject toolHexRead(const QJsonObject& args);
+    QJsonObject toolHexWrite(const QJsonObject& args);
+    QJsonObject toolStatusSet(const QJsonObject& args);
+    QJsonObject toolUiAction(const QJsonObject& args);
+
+    // Helpers
+    QJsonObject makeTextResult(const QString& text, bool isError = false);
+    QString resolvePlaceholder(const QString& ref,
+                               const QHash<QString, uint64_t>& placeholderMap);
+
+    // Smart tab resolution: tabIndex arg → activeTab → first tab → auto-create
+    MainWindow::TabState* resolveTab(const QJsonObject& args);
+};
+
+} // namespace rcx

src/typeselectorpopup.cpp

@@ -131,10 +131,17 @@ TypeSelectorPopup::TypeSelectorPopup(QWidget* parent)
 
         row->addStretch();
 
-        m_escLabel = new QLabel(QStringLiteral("Esc"));
-        QPalette dimPal = pal;
-        dimPal.setColor(QPalette::WindowText, theme.textDim);
-        m_escLabel->setPalette(dimPal);
+        m_escLabel = new QToolButton;
+        m_escLabel->setText(QStringLiteral("\u2715 Esc"));
+        m_escLabel->setAutoRaise(true);
+        m_escLabel->setCursor(Qt::PointingHandCursor);
+        m_escLabel->setStyleSheet(QStringLiteral(
+            "QToolButton { color: %1; border: none; padding: 2px 6px; }"
+            "QToolButton:hover { color: %2; }")
+            .arg(theme.textDim.name(), theme.indHoverSpan.name()));
+        connect(m_escLabel, &QToolButton::clicked, this, [this]() {
+            hide();
+        });
         row->addWidget(m_escLabel);
 
         layout->addLayout(row);
@@ -144,8 +151,7 @@ TypeSelectorPopup::TypeSelectorPopup(QWidget* parent)
     {
         m_createBtn = new QToolButton;
         m_createBtn->setText(QStringLiteral("+ Create new type\u2026"));
-        m_createBtn->setIcon(QIcon(QStringLiteral(":/vsicons/add.svg")));
-        m_createBtn->setToolButtonStyle(Qt::ToolButtonTextBesideIcon);
+        m_createBtn->setToolButtonStyle(Qt::ToolButtonTextOnly);
         m_createBtn->setAutoRaise(true);
         m_createBtn->setCursor(Qt::PointingHandCursor);
         m_createBtn->setPalette(pal);

src/typeselectorpopup.h

@@ -39,7 +39,7 @@ protected:
 
 private:
     QLabel*           m_titleLabel   = nullptr;
-    QLabel*           m_escLabel     = nullptr;
+    QToolButton*      m_escLabel     = nullptr;
     QToolButton*      m_createBtn    = nullptr;
     QLineEdit*        m_filterEdit   = nullptr;
     QListView*        m_listView     = nullptr;