fix(users): show normalized errors when bulk updating limits

frontend/src/components/admin/user/BulkEditUserModal.vue

@@ -93,6 +93,7 @@
 import { computed, ref, watch } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { adminAPI } from '@/api/admin'
+import { extractApiErrorMessage } from '@/utils/apiError'
 import type { BatchUpdateUserLimitsRequest } from '@/api/admin/users'
 import { useAppStore } from '@/stores/app'
 import BaseDialog from '@/components/common/BaseDialog.vue'
@@ -203,9 +204,7 @@ const handleSubmit = async () => {
     emit('close')
   } catch (error: any) {
     appStore.showError(
-      error.response?.data?.message
-      || error.response?.data?.detail
-      || t('admin.users.bulkLimits.failed')
+      extractApiErrorMessage(error, t('admin.users.bulkLimits.failed'))
     )
   } finally {
     submitting.value = false

frontend/src/components/admin/user/__tests__/BulkEditUserModal.spec.ts

@@ -59,6 +59,27 @@ describe('BulkEditUserModal', () => {
     vi.restoreAllMocks()
   })
 
+  it.each([
+    [{ message: 'Selected users are no longer available' }, 'Selected users are no longer available'],
+    [{ response: { data: { message: 'Legacy message' } } }, 'Legacy message'],
+    [{ response: { data: { detail: 'Legacy detail' } } }, 'Legacy detail'],
+    [{}, 'admin.users.bulkLimits.failed'],
+  ])('shows API error details and allows retry after failure', async (error, expected) => {
+    vi.spyOn(window, 'confirm').mockReturnValue(true)
+    batchUpdateLimits.mockRejectedValueOnce(error)
+    const wrapper = mountModal()
+    await wrapper.get('[data-test="enable-concurrency"]').trigger('click')
+    await wrapper.get('[data-test="concurrency-input"]').setValue('5')
+    await wrapper.get('form').trigger('submit')
+    await flushPromises()
+
+    expect(showError).toHaveBeenCalledWith(expected)
+    expect(wrapper.emitted('close')).toBeUndefined()
+    expect(wrapper.emitted('success')).toBeUndefined()
+    expect(wrapper.get('[data-test="submit"]').attributes('disabled')).toBeUndefined()
+    wrapper.unmount()
+  })
+
   it('disables submission until at least one enabled field has a value', async () => {
     const wrapper = mountModal()