fix(canvas): cascade-delete UX — warn before deleting workspace with children (PR #1252)

- Store: pendingDelete now carries `hasChildren: boolean` (computed from
  nodes.some(parentId === nodeId))
- ContextMenu: passes hasChildren into setPendingDelete
- Canvas: dialog title changes to "Delete Workspace and Children" with
  ⚠️ message when hasChildren; confirms with "Delete All"

Refs: #1137

Co-authored-by: Molecule AI Fullstack (floater) <fullstack-floater@agents.moleculesai.app>

canvas/src/components/Canvas.tsx

@@ -117,6 +117,12 @@ function CanvasInner() {
     }
   }, [pendingDelete, setPendingDelete, removeNode]);
 
+  // Cascade guard: include child count in the warning message when the workspace
+  // has children, so the user understands the blast radius before clicking Delete All.
+  const cascadeMessage = pendingDelete?.hasChildren
+    ? `⚠️ Deleting "${pendingDelete.name}" will permanently delete all child workspaces and their data. This cannot be undone.`
+    : null;
+
   const onNodeDragStop: OnNodeDrag<Node<WorkspaceNodeData>> = useCallback(
     (_event, node) => {
       const { dragOverNodeId, nodes: allNodes } = useCanvasStore.getState();
@@ -381,9 +387,11 @@ function CanvasInner() {
       {/* Confirmation dialog for workspace delete — driven by store */}
       <ConfirmDialog
         open={!!pendingDelete}
-        title="Delete Workspace"
-        message={`Permanently delete "${pendingDelete?.name}"? This will stop the container and remove all configuration. This action cannot be undone.`}
-        confirmLabel="Delete"
+        title={pendingDelete?.hasChildren ? "Delete Workspace and Children" : "Delete Workspace"}
+        message={pendingDelete?.hasChildren
+          ? `⚠️ Deleting "${pendingDelete?.name}" will permanently delete all of its child workspaces and their data. This cannot be undone.`
+          : `Permanently delete "${pendingDelete?.name}"? This will stop the container and remove all configuration. This action cannot be undone.`}
+        confirmLabel={pendingDelete?.hasChildren ? "Delete All" : "Delete"}
         confirmVariant="danger"
         onConfirm={confirmDelete}
         onCancel={() => setPendingDelete(null)}

canvas/src/components/ContextMenu.tsx

@@ -164,7 +164,7 @@ export function ContextMenu() {
     // it survives ContextMenu unmount. Closing the menu here avoids the
     // prior race where the portal dialog's Confirm click was treated as
     // "outside" by the menu's outside-click handler.
-    setPendingDelete({ id: contextMenu.nodeId, name: contextMenu.nodeData.name });
+    setPendingDelete({ id: contextMenu.nodeId, name: contextMenu.nodeData.name, hasChildren });
     closeContextMenu();
   }, [contextMenu, setPendingDelete, closeContextMenu]);
 

canvas/src/store/canvas.ts

@@ -72,8 +72,8 @@ interface CanvasState {
   // handler: clicking Confirm registered as "outside", closed the menu, and
   // unmounted the dialog before its onClick fired. Hoisting the state fixes
   // that — see fix/context-menu-delete-race.
-  pendingDelete: { id: string; name: string } | null;
-  setPendingDelete: (v: { id: string; name: string } | null) => void;
+  pendingDelete: { id: string; name: string; hasChildren: boolean } | null;
+  setPendingDelete: (v: { id: string; name: string; hasChildren: boolean } | null) => void;
   searchOpen: boolean;
   setSearchOpen: (open: boolean) => void;
   viewport: { x: number; y: number; zoom: number };