Filter invalid nested drag targets before collision selection

packages/dnd/src/manager.ts

@@ -121,7 +121,15 @@ export function createDndManager(options: DndManagerOptions): DndManager {
           element: registration.element,
           handle: registration.handle,
           type: registration.type,
-          accept: registration.accepts,
+          accept: (source) => {
+            const origin = entries.get(source.id)?.current.element;
+            // A nested ancestor overlaps its own descendants and must not steal
+            // their next keyboard/pointer target just because its box is larger.
+            if (source.id !== registration.id && origin && registration.element.contains?.(origin)) return false;
+            if (registration.accepts && !registration.accepts.some(type => type === source.type)) return false;
+            const target = entries.get(registration.id)?.sortable;
+            return options.accept?.([source.id], { group: target?.group ?? registration.group, index: target?.index ?? registration.index }) ?? true;
+          },
           disabled: registration.disabled,
           transition: reducedMotion ? null : undefined,
           data: { ...registration.data, direction },