diff --git a/src/hooks/useCategories.test.ts b/src/hooks/useCategories.test.ts
index 5e8adf4..6b4bfea 100644
--- a/src/hooks/useCategories.test.ts
+++ b/src/hooks/useCategories.test.ts
@@ -181,7 +181,8 @@ describe("useCategories — « Vérifier la hiérarchie » (#393)", () => {
     let api = await mount();
     await api.checkHierarchy();
     api = harness.render(useCategories);
-    expect(getAllCategoriesWithCounts).toHaveBeenCalledTimes(1);
+    // The mount's read, then the check's.
+    expect(getAllCategoriesWithCounts).toHaveBeenCalledTimes(2);
 
     await api.reattachOrphan(CYCLE, 1);
 
@@ -192,7 +193,7 @@ describe("useCategories — « Vérifier la hiérarchie » (#393)", () => {
     expect(line).toContain("3 categories");
     for (const row of ROWS) expect(line).not.toContain(row.name);
     expect(findOrphanCategories).toHaveBeenCalledTimes(2);
-    expect(getAllCategoriesWithCounts).toHaveBeenCalledTimes(2);
+    expect(getAllCategoriesWithCounts).toHaveBeenCalledTimes(3);
     const { state } = harness.render(useCategories);
     expect(state.hierarchyCheck).toEqual({ orphans: [], error: null });
     expect(state.isSaving).toBe(false);
@@ -209,7 +210,8 @@ describe("useCategories — « Vérifier la hiérarchie » (#393)", () => {
     await api.reattachOrphan(CYCLE, null);
     expect(reattachCategory).toHaveBeenCalledWith(3, null);
     expect(logInfo).toHaveBeenCalledTimes(1);
-    expect(getAllCategoriesWithCounts).toHaveBeenCalledTimes(2);
+    // The mount's read, the check's, and the reload after the committed reattachment.
+    expect(getAllCategoriesWithCounts).toHaveBeenCalledTimes(3);
     const { state } = harness.render(useCategories);
     expect(state.hierarchyCheck?.error).toEqual({ message: "database is locked" });
     expect(state.isSaving).toBe(false);
@@ -232,6 +234,50 @@ describe("useCategories — « Vérifier la hiérarchie » (#393)", () => {
     expect(logInfo).not.toHaveBeenCalled();
   });
 
+  it("a refusal, then a reattachment that goes through: the window's message goes", async () => {
+    vi.mocked(findOrphanCategories).mockResolvedValueOnce([CYCLE]).mockResolvedValueOnce([]);
+    vi.mocked(reattachCategory)
+      .mockRejectedValueOnce(new CategoryHierarchyError("parent_has_transactions"))
+      .mockResolvedValueOnce(3);
+    let api = await mount();
+    await api.checkHierarchy();
+    api = harness.render(useCategories);
+    await api.reattachOrphan(CYCLE, 1);
+    api = harness.render(useCategories);
+    expect(api.state.hierarchyCheck?.error).toEqual({ key: "categories.hierarchy.errors.parent_has_transactions" });
+    await api.reattachOrphan(CYCLE, null);
+    expect(harness.render(useCategories).state.hierarchyCheck).toEqual({ orphans: [], error: null });
+  });
+
+  it("after a drag-and-drop, reads the categories again: the window gets the members of a loop back", async () => {
+    // 1 with 10 under it, 2, and 3 <-> 5: no root reaches 3 nor 5.
+    const row = (id: number, parent_id: number | null) => ({ ...ROWS[1], id, name: `c${id}`, parent_id, sort_order: id });
+    vi.mocked(getAllCategoriesWithCounts).mockResolvedValue([
+      row(1, null),
+      row(10, 1),
+      row(2, null),
+      row(3, 5),
+      row(5, 3),
+    ] as never);
+    vi.mocked(findOrphanCategories).mockResolvedValue([CYCLE]);
+    let api = await mount();
+    const ids = () => harness.render(useCategories).state.categories.map((c) => c.id).sort((a, b) => a - b);
+    expect(ids()).toEqual([1, 2, 3, 5, 10]);
+
+    await api.moveCategory(2, null, 0);
+    // The drag-and-drop keeps what the tree shows: the loop is gone from the list.
+    expect(ids()).toEqual([1, 2, 10]);
+
+    api = harness.render(useCategories);
+    harness.dispatch.mockClear();
+    await api.checkHierarchy();
+    expect(ids()).toEqual([1, 2, 3, 5, 10]);
+    expect(harness.render(useCategories).state.hierarchyCheck).toEqual({ orphans: [CYCLE], error: null });
+    // Read without the page's loading state: the tree and an open form stay on screen.
+    const types = harness.dispatch.mock.calls.map(([action]) => (action as { type: string }).type);
+    expect(types).not.toContain("SET_LOADING");
+  });
+
   it("closes the window; a check that ends after it closed changes nothing", async () => {
     let resolve: (orphans: OrphanCategory[]) => void = () => undefined;
     vi.mocked(findOrphanCategories).mockReturnValue(new Promise((r) => (resolve = r)));
diff --git a/src/hooks/useCategories.ts b/src/hooks/useCategories.ts
index 711269e..0826f3c 100644
--- a/src/hooks/useCategories.ts
+++ b/src/hooks/useCategories.ts
@@ -403,10 +403,23 @@ export function useCategories() {
     [state.tree, loadCategories]
   );
 
-  /** Opens the « Vérifier la hiérarchie » window and runs the diagnostic (#393). */
+  /**
+   * Opens the « Vérifier la hiérarchie » window and runs the diagnostic (#393).
+   * The window names the orphans and offers their parents from
+   * `state.categories`, which a drag-and-drop leaves with what the tree shows
+   * only (`SET_TREE`), without the categories no root reaches: the categories
+   * are read again first. Without the page's loading state, so a form open
+   * behind the window stays as it is; a load started meanwhile wins.
+   */
   const checkHierarchy = useCallback(async () => {
     dispatch({ type: "OPEN_HIERARCHY_CHECK" });
     try {
+      const fetchId = fetchIdRef.current;
+      const rows = await getAllCategoriesWithCounts();
+      if (fetchId === fetchIdRef.current) {
+        const flat = rows.map((r) => ({ ...r, children: [] as CategoryTreeNode[] }));
+        dispatch({ type: "SET_CATEGORIES", payload: { flat, tree: buildTree(flat) } });
+      }
       const orphans = await findOrphanCategories();
       dispatch({ type: "SET_ORPHANS", payload: orphans });
     } catch (e) {