diff --git a/src/controller.cpp b/src/controller.cpp
index 80bd009..6e88b67 100644
--- a/src/controller.cpp
+++ b/src/controller.cpp
@@ -165,6 +165,12 @@ RcxController::~RcxController() {
         m_refreshWatcher->cancel();
         m_refreshWatcher->waitForFinished();
     }
+
+    m_snapshotProv.reset();
+}
+
+void RcxController::resetProvider() {
+    m_snapshotProv.reset();
 }
 
 RcxEditor* RcxController::primaryEditor() const {
diff --git a/src/controller.h b/src/controller.h
index c0d543e..d9a5c57 100644
--- a/src/controller.h
+++ b/src/controller.h
@@ -127,6 +127,7 @@ public:
     void setEditorFont(const QString& fontName);
     void setRefreshInterval(int ms);
     void setCompactColumns(bool v);
+    void resetProvider();
 
     // MCP bridge accessors
     void setSuppressRefresh(bool v) { m_suppressRefresh = v; }
diff --git a/src/main.cpp b/src/main.cpp
index 4f1ca7a..6e9f258 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -109,7 +109,7 @@ static LONG WINAPI crashHandler(EXCEPTION_POINTERS* ep) {
         SYSTEMTIME st;
         GetLocalTime(&st);
         wchar_t dumpPath[MAX_PATH];
-        _snwprintf(dumpPath, MAX_PATH,
+        _snwprintf_s(dumpPath, MAX_PATH,
                    L"%sreclass_crash_%04d%02d%02d_%02d%02d%02d.dmp",
                    exePath, st.wYear, st.wMonth, st.wDay,
                    st.wHour, st.wMinute, st.wSecond);
@@ -1391,6 +1391,28 @@ static void buildEmptyStruct(NodeTree& tree, const QString& classKeyword = QStri
     }
 }
 
+MainWindow::~MainWindow() {
+    /*
+     * When MainWindow is destroyed:
+     *
+	 *	  1. ~MainWindow() runs (our code — plugin DLLs still loaded)
+	 *	  2. MainWindow member variables are destroyed (m_pluginManager — unloads plugin DLLs)
+	 *	  3. QObject::~QObject() runs — destroys child widgets (QMdiSubWindow → RcxController → ~RcxController())
+     * 
+     */
+
+    // Disconnect all subwindow destroyed signals before members are torn down,
+    // so the lambdas capturing 'this' never fire on a half-destroyed object.
+    for (auto it = m_tabs.begin(); it != m_tabs.end(); ++it) {
+        disconnect(it.key(), &QObject::destroyed, this, nullptr);
+        // Release providers now while plugin DLLs are still loaded;
+        // if deferred to Qt child cleanup the DLL code may already be unloaded.
+        it->doc->provider.reset();
+        it->ctrl->resetProvider();
+    }
+    m_tabs.clear();
+}
+
 void MainWindow::newClass() {
     project_new(QStringLiteral("class"));
 }
diff --git a/src/mainwindow.h b/src/mainwindow.h
index b90b7ca..fb28e03 100644
--- a/src/mainwindow.h
+++ b/src/mainwindow.h
@@ -30,6 +30,7 @@ class MainWindow : public QMainWindow {
     friend class McpBridge;
 public:
     explicit MainWindow(QWidget* parent = nullptr);
+    ~MainWindow() override;
 
 private slots:
     void newClass();