Fix process memory provider base address sync and live refresh

Provider base address now stays in sync with tree base address when
changed via ChangeBase command, fixing reads from arbitrary memory
regions like KUSER_SHARED_DATA at 0x7FFE0000. ReadProcessMemory
handles partial reads gracefully. Snapshot extent uses tree-based
calculation instead of provider size to avoid oversized reads.
MCP source.switch gains pid parameter for programmatic process attach.
MCP server starts by default with logging and slow mode support.

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

plugins/ProcessMemory/ProcessMemoryPlugin.cpp

@@ -62,9 +62,10 @@ bool ProcessMemoryProvider::read(uint64_t addr, void* buf, int len) const
     if (!m_handle || len <= 0) return false;
 
     SIZE_T bytesRead = 0;
-    if (ReadProcessMemory(m_handle, (LPCVOID)(m_base + addr), buf, (SIZE_T)len, &bytesRead))
+    ReadProcessMemory(m_handle, (LPCVOID)(m_base + addr), buf, (SIZE_T)len, &bytesRead);
-        return bytesRead == (SIZE_T)len;
+    if ((int)bytesRead < len)
-    return false;
+        memset((char*)buf + bytesRead, 0, len - bytesRead);
+    return bytesRead > 0;
 }
 
 bool ProcessMemoryProvider::write(uint64_t addr, const void* buf, int len)
@@ -298,9 +299,9 @@ ProcessMemoryProvider::~ProcessMemoryProvider()
 int ProcessMemoryProvider::size() const
 {
 #ifdef _WIN32
-    return m_handle ? INT_MAX : 0;
+    return m_handle ? 0x10000 : 0;
 #elif defined(__linux__)
-    return m_fd ? INT_MAX : 0;
+    return (m_fd >= 0) ? 0x10000 : 0;
 #endif
 }
 

plugins/ProcessMemory/ProcessMemoryPlugin.h

@@ -25,6 +25,10 @@ public:
     QString kind() const override { return QStringLiteral("LocalProcess"); }
     QString getSymbol(uint64_t addr) const override;
 
+    bool isLive() const override { return true; }
+    uint64_t base() const override { return m_base; }
+    void setBase(uint64_t b) override { m_base = b; }
+
     // Process-specific helpers
     uint32_t pid() const { return m_pid; }
     uint64_t baseAddress() const { return m_base; }

src/controller.cpp

@@ -447,9 +447,12 @@ void RcxController::connectEditor(RcxEditor* editor) {
 
                         // Apply provider or show error
                         if (provider) {
+                            uint64_t newBase = provider->base();
                             m_doc->undoStack.clear();
                             m_doc->provider = std::move(provider);
                             m_doc->dataPath.clear();
+                            m_doc->tree.baseAddress = newBase;
+                            resetSnapshot();
                             emit m_doc->documentChanged();
                             refresh();
                         } else if (!errorMsg.isEmpty()) {
@@ -860,6 +863,13 @@ void RcxController::applyCommand(const Command& command, bool isUndo) {
             }
         } else if constexpr (std::is_same_v<T, cmd::ChangeBase>) {
             tree.baseAddress = isUndo ? c.oldBase : c.newBase;
+            qDebug() << "[ChangeBase] tree.baseAddress =" << Qt::hex << tree.baseAddress
+                     << "provider =" << (m_doc->provider ? "yes" : "null");
+            if (m_doc->provider) {
+                m_doc->provider->setBase(tree.baseAddress);
+                qDebug() << "[ChangeBase] provider->base() now =" << Qt::hex << m_doc->provider->base();
+            }
+            resetSnapshot();
         } else if constexpr (std::is_same_v<T, cmd::WriteBytes>) {
             const QByteArray& bytes = isUndo ? c.oldBytes : c.newBytes;
             if (!m_doc->provider->writeBytes(c.addr, bytes))
@@ -1585,6 +1595,9 @@ void RcxController::attachToProcess(uint32_t pid, const QString& processName) {
         }
     }
 
+    qDebug() << "[AttachProcess]" << processName << "PID" << pid
+             << "base" << Qt::hex << base << "regionSize" << regionSize;
+
     m_doc->undoStack.clear();
     m_doc->provider = std::make_shared<ProcessProvider>(
         hProc, base, regionSize, processName);
@@ -1662,6 +1675,8 @@ void RcxController::onRefreshTick() {
 
     // Capture shared_ptr copy — keeps provider alive during async read
     auto prov = m_doc->provider;
+    uint64_t base = prov->base();
+    qDebug() << "[Refresh] reading" << extent << "bytes from base" << Qt::hex << base;
     m_refreshWatcher->setFuture(QtConcurrent::run([prov, extent]() -> QByteArray {
         return prov->readBytes(0, extent);
     }));
@@ -1709,19 +1724,20 @@ void RcxController::onReadComplete() {
 }
 
 int RcxController::computeDataExtent() const {
-    // Use provider size as the extent (for ProcessProvider this is the module/region size)
+    // Prefer tree-based extent: exact bytes needed for rendering
-    int provSize = m_doc->provider->size();
+    int treeExtent = 0;
-    if (provSize > 0) return provSize;
-
-    // Fallback: walk tree to find maximum byte offset
-    int maxEnd = 0;
     for (int i = 0; i < m_doc->tree.nodes.size(); i++) {
         int64_t off = m_doc->tree.computeOffset(i);
         int sz = m_doc->tree.nodes[i].byteSize();
         int end = (int)(off + sz);
-        if (end > maxEnd) maxEnd = end;
+        if (end > treeExtent) treeExtent = end;
     }
-    return maxEnd;
+    if (treeExtent > 0) return treeExtent;
+
+    // Fallback: provider size (empty tree)
+    int provSize = m_doc->provider->size();
+    if (provSize > 0) return provSize;
+    return 0;
 }
 
 void RcxController::resetSnapshot() {

src/controller.h

@@ -112,6 +112,7 @@ public:
 
     // MCP bridge accessors
     void setSuppressRefresh(bool v) { m_suppressRefresh = v; }
+    void attachToProcess(uint32_t pid, const QString& processName);
     const QVector<SavedSourceEntry>& savedSources() const { return m_savedSources; }
     int activeSourceIndex() const { return m_activeSourceIdx; }
     void switchSource(int idx) { switchToSavedSource(idx); }
@@ -147,7 +148,6 @@ private:
     void handleMarginClick(RcxEditor* editor, int margin, int line, Qt::KeyboardModifiers mods);
     void updateCommandRow();
     void performRealignment(uint64_t structId, int targetAlign);
-    void attachToProcess(uint32_t pid, const QString& processName);
     void switchToSavedSource(int idx);
     void pushSavedSourcesToEditors();
     void showTypeSelectorPopup(RcxEditor* editor);

src/main.cpp

@@ -209,8 +209,9 @@ MainWindow::MainWindow(QWidget* parent) : QMainWindow(parent) {
     // Load plugins
     m_pluginManager.LoadPlugins();
 
-    // MCP bridge (stopped by default — user starts via File → Start MCP)
+    // MCP bridge (on by default)
     m_mcp = new McpBridge(this, this);
+    m_mcp->start();
 
     connect(m_mdiArea, &QMdiArea::subWindowActivated,
             this, [this](QMdiSubWindow*) {
@@ -248,7 +249,7 @@ 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);
+    m_mcpAction = file->addAction("Stop &MCP Server", this, &MainWindow::toggleMcp);
     file->addSeparator();
     file->addAction(makeIcon(":/vsicons/close.svg"), "E&xit", QKeySequence(Qt::Key_Close), this, &QMainWindow::close);
 

src/mcp/mcp_bridge.cpp

@@ -123,6 +123,7 @@ QJsonObject McpBridge::errReply(const QJsonValue& id, int code, const QString& m
 void McpBridge::sendJson(const QJsonObject& obj) {
     if (!m_client) return;
     QByteArray data = QJsonDocument(obj).toJson(QJsonDocument::Compact);
+    qDebug() << "[MCP] >>" << data.left(200);
     data.append('\n');
     m_client->write(data);
     m_client->flush();
@@ -151,6 +152,7 @@ QJsonObject McpBridge::makeTextResult(const QString& text, bool isError) {
 // ════════════════════════════════════════════════════════════════════
 
 void McpBridge::processLine(const QByteArray& line) {
+    qDebug() << "[MCP] <<" << line.trimmed().left(200);
     auto doc = QJsonDocument::fromJson(line);
     if (!doc.isObject()) {
         sendJson(errReply(QJsonValue(), -32700, "Parse error"));
@@ -263,7 +265,7 @@ QJsonObject McpBridge::handleToolsList(const QJsonValue& id) {
     tools.append(QJsonObject{
         {"name", "source.switch"},
         {"description", "Switch active data source (provider). Use sourceIndex for saved sources, "
-                        "or filePath to load a new binary file."},
+                        "filePath to load a binary file, or pid to attach to a live process."},
         {"inputSchema", QJsonObject{
             {"type", "object"},
             {"properties", QJsonObject{
@@ -271,6 +273,10 @@ QJsonObject McpBridge::handleToolsList(const QJsonValue& id) {
                     {"description", "MDI tab index (0-based). Omit for active tab."}}},
                 {"sourceIndex", QJsonObject{{"type", "integer"}}},
                 {"filePath", QJsonObject{{"type", "string"}}},
+                {"pid", QJsonObject{{"type", "integer"},
+                    {"description", "Process ID to attach to for live memory reading."}}},
+                {"processName", QJsonObject{{"type", "string"},
+                    {"description", "Display name for the process (optional with pid)."}}},
                 {"allViews", QJsonObject{{"type", "boolean"}}}
             }}
         }}
@@ -549,10 +555,12 @@ QJsonObject McpBridge::toolTreeApply(const QJsonObject& args) {
     }
 
     // Phase 2: Execute in undo macro
+    if (!m_slowMode)
         ctrl->setSuppressRefresh(true);
     doc->undoStack.beginMacro(macroName);
 
     int applied = 0;
+    uint64_t lastRootStructId = 0;  // track root-level struct inserts
     QStringList skippedOps;
     for (int i = 0; i < ops.size(); i++) {
         // Safety valve: keep paint events flowing for large batches
@@ -594,6 +602,8 @@ QJsonObject McpBridge::toolTreeApply(const QJsonObject& args) {
             }
 
             doc->undoStack.push(new RcxCommand(ctrl, cmd::Insert{n, {}}));
+            if (n.parentId == 0 && n.kind == NodeKind::Struct)
+                lastRootStructId = n.id;
             applied++;
         }
         else if (opType == "remove") {
@@ -722,10 +732,22 @@ QJsonObject McpBridge::toolTreeApply(const QJsonObject& args) {
         else {
             skippedOps.append(QStringLiteral("op[%1]: unknown op '%2'").arg(i).arg(opType));
         }
+
+        // Slow mode: refresh after each operation for visual feedback
+        if (m_slowMode && applied > 0) {
+            ctrl->refresh();
+            QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents, 16);
+        }
     }
 
     doc->undoStack.endMacro();
+    if (!m_slowMode)
         ctrl->setSuppressRefresh(false);
+
+    // Auto-switch view to newly created root struct
+    if (lastRootStructId)
+        ctrl->setViewRootId(lastRootStructId);
+
     ctrl->refresh();
 
     // Build response with assigned placeholder IDs
@@ -770,6 +792,14 @@ QJsonObject McpBridge::toolSourceSwitch(const QJsonObject& args) {
                               " (" + sources[idx].displayName + ")");
     }
 
+    if (args.contains("pid")) {
+        uint32_t pid = (uint32_t)args.value("pid").toInteger();
+        QString name = args.value("processName").toString();
+        if (name.isEmpty()) name = QString("PID %1").arg(pid);
+        ctrl->attachToProcess(pid, name);
+        return makeTextResult("Attached to process " + name + " (PID " + QString::number(pid) + ")");
+    }
+
     if (args.contains("filePath")) {
         QString path = args.value("filePath").toString();
         doc->loadData(path);
@@ -777,7 +807,7 @@ QJsonObject McpBridge::toolSourceSwitch(const QJsonObject& args) {
         return makeTextResult("Loaded file: " + path);
     }
 
-    return makeTextResult("Provide sourceIndex or filePath", true);
+    return makeTextResult("Provide sourceIndex, filePath, or pid", true);
 }
 
 // ════════════════════════════════════════════════════════════════════

src/mcp/mcp_bridge.h

@@ -20,6 +20,9 @@ public:
     void stop();
     bool isRunning() const { return m_server != nullptr; }
 
+    bool slowMode() const { return m_slowMode; }
+    void setSlowMode(bool v) { m_slowMode = v; }
+
     // Call from controller refresh / data change to notify MCP clients
     void notifyTreeChanged();
     void notifyDataChanged();
@@ -30,6 +33,7 @@ private:
     QLocalSocket*  m_client    = nullptr;  // single client for v1
     QByteArray     m_readBuffer;
     bool           m_initialized = false;
+    bool           m_slowMode    = false;
 
     // JSON-RPC plumbing
     void onNewConnection();

src/providers/process_provider.h

@@ -38,10 +38,13 @@ public:
     bool isReadable(uint64_t, int len) const override { return len >= 0; }
 
     bool read(uint64_t addr, void* buf, int len) const override {
+        if (!m_handle || len <= 0) return false;
         SIZE_T got = 0;
-        BOOL ok = ReadProcessMemory(m_handle,
+        ReadProcessMemory(m_handle,
             (LPCVOID)(m_base + addr), buf, len, &got);
-        return ok && (int)got == len;
+        if ((int)got < len)
+            memset((char*)buf + got, 0, len - got);
+        return got > 0;
     }
 
     bool isWritable() const override { return true; }
@@ -73,6 +76,8 @@ public:
 
     HANDLE handle() const { return m_handle; }
     uint64_t baseAddress() const { return m_base; }
+    uint64_t base() const override { return m_base; }
+    void setBase(uint64_t b) override { m_base = b; }
     void refreshModules() { m_modules.clear(); cacheModules(); }
 
 private:

src/providers/provider.h

@@ -33,6 +33,11 @@ public:
     // Examples: "File", "Process", "Socket"
     virtual QString kind() const { return QStringLiteral("File"); }
 
+    // Base address for providers that offset reads (e.g. process memory).
+    // For file/buffer providers this is always 0.
+    virtual uint64_t base() const { return 0; }
+    virtual void setBase(uint64_t newBase) { Q_UNUSED(newBase); }
+
     // Resolve an absolute address to a symbol name.
     // Returns empty string if no symbol is known.
     // ProcessProvider: "ntdll.dll+0x1A30"