fix(dnd): validate proposed hover destinations

packages/block-editor/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@wrnexus/block-editor",
-  "version": "0.1.2",
+  "version": "0.1.3",
   "type": "module",
   "description": "Hydrated accessible editor runtime for WRNexus block documents.",
   "exports": {

packages/block-editor/src/runtime.ts

@@ -7,6 +7,10 @@ export interface MountedEditor {
 export interface MountEditorOptions {
   direction?: "ltr" | "rtl";
   announce?(announcement: DndAnnouncement): string;
+  canMove?(intent: {
+    nodeIds: string[];
+    to: { parentId: string; slot: string; index: number };
+  }): boolean;
   onMove(intent: {
     nodeIds: string[];
     to: { parentId: string; slot: string; index: number };
@@ -37,6 +41,19 @@ export function mountBlockEditor(root: HTMLElement, options: MountEditorOptions)
     let gesture = 0;
     const groups = new Map<string, { parentId: string; slot: string }>();
     manager = createDndManager({
+      accept(ids, location) {
+        const destination = groups.get(String(location.group));
+        return (
+          !destroyed &&
+          generation === currentGeneration &&
+          !!destination &&
+          (options.canMove?.({
+            nodeIds: ids.map(String),
+            to: { ...destination, index: location.index },
+          }) ??
+            true)
+        );
+      },
       direction:
         options.direction ?? (view.getComputedStyle(root).direction === "rtl" ? "rtl" : "ltr"),
       reducedMotion: view.matchMedia("(prefers-reduced-motion: reduce)").matches,

packages/dnd/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@wrnexus/dnd",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "type": "module",
   "description": "Stable accessible drag-and-drop primitives for WRNexus.",
   "exports": {

packages/dnd/src/manager.ts

@@ -36,7 +36,10 @@ export function createDndManager(options: DndManagerOptions): DndManager {
     const source = event.operation.source as
       (typeof event.operation.source & { group?: string | number; index?: number }) | null;
     if (!source) return;
-    const destination = { group: source.group ?? "default", index: source.index ?? 0 };
+    const target = event.operation.target as
+      (typeof event.operation.target & { group?: string | number; index?: number }) | null;
+    if (!target) return;
+    const destination = { group: target.group ?? "default", index: target.index ?? 0 };
     if (options.accept && !options.accept(activeIds, destination)) {
       event.preventDefault();
       options.announce?.({ type: "invalid", ids: activeIds, location: destination });

packages/dnd/test/manager-lifecycle.test.ts

@@ -55,6 +55,17 @@ function fixture(overrides: Partial<DndManagerOptions> = {}) {
     instances,
     start: (id: string) => listeners.dragstart!(event(id)),
     end: (id: string) => listeners.dragend!(event(id)),
+    over: (target: { group: string; index: number }) => {
+      let prevented = false;
+      listeners.dragover!({
+        ...event("first"),
+        operation: { ...event("first").operation, target },
+        preventDefault: () => {
+          prevented = true;
+        },
+      });
+      return prevented;
+    },
     get managerDestructions() {
       return managerDestructions;
     },
@@ -82,6 +93,14 @@ test("late drop resolution cannot clear or announce a newer gesture", async () =
   ]);
 });
 
+test("hover acceptance checks the proposed target instead of the source's old group", () => {
+  const f = fixture({ accept: (_ids, to) => to.group === "allowed" });
+  f.start("first");
+  expect(f.over({ group: "blocked", index: 2 })).toBe(true);
+  expect(f.announcements.at(-1)?.location).toEqual({ group: "blocked", index: 2 });
+  expect(f.over({ group: "allowed", index: 0 })).toBe(false);
+});
+
 test("drop commit rejection reports cancellation and its original intent", async () => {
   const failure = new Error("save failed");
   const errors: unknown[] = [];