diff --git a/plugins/ProcessMemory/ProcessMemoryPlugin.cpp b/plugins/ProcessMemory/ProcessMemoryPlugin.cpp
index 2f04b4e..8a9ff0f 100644
--- a/plugins/ProcessMemory/ProcessMemoryPlugin.cpp
+++ b/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))
-        return bytesRead == (SIZE_T)len;
-    return false;
+    ReadProcessMemory(m_handle, (LPCVOID)(m_base + addr), buf, (SIZE_T)len, &bytesRead);
+    if ((int)bytesRead < len)
+        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
 }
 
diff --git a/plugins/ProcessMemory/ProcessMemoryPlugin.h b/plugins/ProcessMemory/ProcessMemoryPlugin.h
index 089d4fc..8c2ab1e 100644
--- a/plugins/ProcessMemory/ProcessMemoryPlugin.h
+++ b/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; }
diff --git a/src/controller.cpp b/src/controller.cpp
index bf6e02d..93f04ef 100644
--- a/src/controller.cpp
+++ b/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)
-    int provSize = m_doc->provider->size();
-    if (provSize > 0) return provSize;
-
-    // Fallback: walk tree to find maximum byte offset
-    int maxEnd = 0;
+    // Prefer tree-based extent: exact bytes needed for rendering
+    int treeExtent = 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() {
diff --git a/src/controller.h b/src/controller.h
index 6c95b05..11f7f71 100644
--- a/src/controller.h
+++ b/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);
diff --git a/src/main.cpp b/src/main.cpp
index 19c5955..4ac27f3 100644
--- a/src/main.cpp
+++ b/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);
 
diff --git a/src/mcp/mcp_bridge.cpp b/src/mcp/mcp_bridge.cpp
index 9b62f9b..1be8b67 100644
--- a/src/mcp/mcp_bridge.cpp
+++ b/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
-    ctrl->setSuppressRefresh(true);
+    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();
-    ctrl->setSuppressRefresh(false);
+    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);
 }
 
 // ════════════════════════════════════════════════════════════════════
diff --git a/src/mcp/mcp_bridge.h b/src/mcp/mcp_bridge.h
index 72389ca..2f1d8ab 100644
--- a/src/mcp/mcp_bridge.h
+++ b/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();
diff --git a/src/providers/process_provider.h b/src/providers/process_provider.h
index cec764d..56aefd8 100644
--- a/src/providers/process_provider.h
+++ b/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:
diff --git a/src/providers/provider.h b/src/providers/provider.h
index fc700ae..9c9d1c6 100644
--- a/src/providers/provider.h
+++ b/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"