feat: safe workspace tree deletion with reference cleanup and confirmation

- Add deleteRootStruct() that clears orphaned refId references before removal
- Show confirmation dialog listing all fields that reference the deleted type
- Auto-switch view to next root struct when the viewed one is deleted
- Entire operation is a single undo macro (Ctrl+Z restores everything)

src/controller.cpp

@@ -776,6 +776,48 @@ void RcxController::removeNode(int nodeIdx) {
         cmd::Remove{nodeId, subtree, adjs}));
 }
 
+void RcxController::deleteRootStruct(uint64_t structId) {
+    int ni = m_doc->tree.indexOfId(structId);
+    if (ni < 0) return;
+    const Node& node = m_doc->tree.nodes[ni];
+    if (node.parentId != 0 || node.kind != NodeKind::Struct) return;
+
+    bool wasSuppressed = m_suppressRefresh;
+    m_suppressRefresh = true;
+    m_doc->undoStack.beginMacro(QStringLiteral("Delete root struct"));
+
+    // Clear all refId references pointing to this struct
+    for (int i = 0; i < m_doc->tree.nodes.size(); i++) {
+        auto& n = m_doc->tree.nodes[i];
+        if (n.refId == structId) {
+            m_doc->undoStack.push(new RcxCommand(this,
+                cmd::ChangePointerRef{n.id, n.refId, (uint64_t)0}));
+        }
+    }
+
+    // Remove the struct + subtree (re-lookup since commands may shift indices)
+    ni = m_doc->tree.indexOfId(structId);
+    if (ni >= 0)
+        removeNode(ni);
+
+    m_doc->undoStack.endMacro();
+    m_suppressRefresh = wasSuppressed;
+
+    // Switch view if we just deleted the viewed root
+    if (m_viewRootId == structId) {
+        uint64_t nextRoot = 0;
+        for (const auto& n : m_doc->tree.nodes) {
+            if (n.parentId == 0 && n.kind == NodeKind::Struct) {
+                nextRoot = n.id;
+                break;
+            }
+        }
+        setViewRootId(nextRoot);
+    }
+
+    if (!m_suppressRefresh) refresh();
+}
+
 void RcxController::toggleCollapse(int nodeIdx) {
     if (nodeIdx < 0 || nodeIdx >= m_doc->tree.nodes.size()) return;
     auto& node = m_doc->tree.nodes[nodeIdx];

src/controller.h

@@ -99,6 +99,7 @@ public:
     void showContextMenu(RcxEditor* editor, int line, int nodeIdx, int subLine, const QPoint& globalPos);
     void batchRemoveNodes(const QVector<int>& nodeIndices);
     void batchChangeKind(const QVector<int>& nodeIndices, NodeKind newKind);
+    void deleteRootStruct(uint64_t structId);
 
     void applyCommand(const Command& cmd, bool isUndo);
     void refresh();

src/main.cpp

@@ -1698,7 +1698,53 @@ void MainWindow::createWorkspaceDock() {
 
         QAction* chosen = menu.exec(m_workspaceTree->viewport()->mapToGlobal(pos));
         if (chosen == actDelete) {
-            tab.ctrl->removeNode(ni);
+            QString typeName = tab.doc->tree.nodes[ni].structTypeName.isEmpty()
+                ? tab.doc->tree.nodes[ni].name
+                : tab.doc->tree.nodes[ni].structTypeName;
+            if (typeName.isEmpty()) typeName = QStringLiteral("(unnamed)");
+
+            // Collect detailed reference info
+            QStringList refDetails;
+            for (const auto& n : tab.doc->tree.nodes) {
+                if (n.refId == structId) {
+                    QString ownerName;
+                    uint64_t pid = n.parentId;
+                    while (pid != 0) {
+                        int pi = tab.doc->tree.indexOfId(pid);
+                        if (pi < 0) break;
+                        if (tab.doc->tree.nodes[pi].parentId == 0) {
+                            ownerName = tab.doc->tree.nodes[pi].structTypeName.isEmpty()
+                                ? tab.doc->tree.nodes[pi].name
+                                : tab.doc->tree.nodes[pi].structTypeName;
+                            break;
+                        }
+                        pid = tab.doc->tree.nodes[pi].parentId;
+                    }
+                    QString fieldDesc = ownerName.isEmpty()
+                        ? n.name
+                        : QStringLiteral("%1::%2").arg(ownerName, n.name);
+                    refDetails << QStringLiteral("  \u2022 %1 (%2)")
+                        .arg(fieldDesc, kindToString(n.kind));
+                }
+            }
+
+            QString msg;
+            if (refDetails.isEmpty()) {
+                msg = QString("Delete '%1'?").arg(typeName);
+            } else {
+                msg = QString("Delete '%1'?\n\n"
+                              "The following %2 field(s) reference this type "
+                              "and will become untyped (void):\n\n%3")
+                    .arg(typeName)
+                    .arg(refDetails.size())
+                    .arg(refDetails.join('\n'));
+            }
+
+            auto answer = QMessageBox::question(this, "Delete Type", msg,
+                QMessageBox::Yes | QMessageBox::No, QMessageBox::No);
+            if (answer != QMessageBox::Yes) return;
+
+            tab.ctrl->deleteRootStruct(structId);
             rebuildWorkspaceModel();
         } else if (chosen && chosen == actConvert) {
             QString newKw = kw == QStringLiteral("class")