diff --git a/apps/app/src/components/timetable/AddPerformanceDialog.vue b/apps/app/src/components/timetable/AddPerformanceDialog.vue
index 84c0b1de..a1e3d2a4 100644
--- a/apps/app/src/components/timetable/AddPerformanceDialog.vue
+++ b/apps/app/src/components/timetable/AddPerformanceDialog.vue
@@ -96,6 +96,11 @@ async function submit(): Promise<void> {
     errors.value._ = (err as Error).message ?? 'Onbekende fout'
   }
 }
+
+// Test seam (Session 4 follow-up): expose form + errors + submit so jsdom
+// component tests can drive validation deterministically without piping
+// through Flatpickr / VAutocomplete plumbing.
+defineExpose({ form, errors, submit })
 </script>
 
 <template>
diff --git a/apps/app/tests/component/AddPerformanceDialog.test.ts b/apps/app/tests/component/AddPerformanceDialog.test.ts
new file mode 100644
index 00000000..da938d99
--- /dev/null
+++ b/apps/app/tests/component/AddPerformanceDialog.test.ts
@@ -0,0 +1,206 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { defineComponent, h } from 'vue'
+import { mountWithVuexy } from '../utils/mountWithVuexy'
+import AddPerformanceDialog from '@/components/timetable/AddPerformanceDialog.vue'
+import { apiClient } from '@/lib/axios'
+import {
+  type ArtistEngagement,
+  ArtistEngagementStatus,
+  type Stage,
+} from '@/types/timetable'
+
+vi.mock('@/lib/axios', () => {
+  const post = vi.fn()
+  const put = vi.fn()
+  const get = vi.fn()
+  const del = vi.fn()
+
+  return { apiClient: { post, put, get, delete: del } }
+})
+
+interface MockApi {
+  post: ReturnType<typeof vi.fn>
+  put: ReturnType<typeof vi.fn>
+  get: ReturnType<typeof vi.fn>
+  delete: ReturnType<typeof vi.fn>
+}
+
+const mocked = apiClient as unknown as MockApi
+
+const stage: Stage = {
+  id: 's1',
+  event_id: 'ev1',
+  name: 'Hardstyle District',
+  color: '#e85d75',
+  capacity: 1000,
+  sort_order: 0,
+  created_at: null,
+  updated_at: null,
+}
+
+const engagement: Partial<ArtistEngagement> = {
+  id: 'e1',
+  artist: { id: 'a1', name: 'Devin Wild' } as ArtistEngagement['artist'],
+  booking_status: { value: ArtistEngagementStatus.REQUESTED, label: 'Aangevraagd' },
+}
+
+// VDialog teleports to body, which puts content outside the wrapper. Stub it
+// so the form renders inline. App* wrappers stubbed too — we don't want to
+// drive Flatpickr / VAutocomplete plumbing here; we want to assert that the
+// schema validation + submit pipeline does the right thing.
+const VDialogStub = defineComponent({
+  name: 'VDialog',
+  props: ['modelValue'],
+  setup(_, { slots }) {
+    return () => h('div', { class: 'v-dialog-stub' }, slots.default?.())
+  },
+})
+
+interface AppFieldProps {
+  modelValue?: unknown
+  label?: string
+  errorMessages?: string
+}
+
+function makeAppFieldStub(name: string) {
+  return defineComponent({
+    name,
+    props: ['modelValue', 'label', 'errorMessages'],
+    setup(props: AppFieldProps) {
+      return () => h('div', { 'class': `${name}-stub`, 'data-label': props.label }, [
+        props.errorMessages ? h('span', { 'class': 'error', 'data-test': `error-${String(props.label).toLowerCase()}` }, String(props.errorMessages)) : null,
+      ])
+    },
+  })
+}
+
+const appStubs = {
+  VDialog: VDialogStub,
+  AppTextField: makeAppFieldStub('AppTextField'),
+  AppTextarea: makeAppFieldStub('AppTextarea'),
+  AppSelect: makeAppFieldStub('AppSelect'),
+  AppAutocomplete: makeAppFieldStub('AppAutocomplete'),
+  AppDateTimePicker: makeAppFieldStub('AppDateTimePicker'),
+}
+
+interface ExposedShape {
+  form: { value: { engagement_id: string; stage_id: string | null; start_at: string; end_at: string; lane: number; notes: string } }
+  errors: { value: Record<string, string> }
+  submit: () => Promise<void>
+}
+
+function getExposed(wrapper: { vm: object }): ExposedShape {
+  // VTU2 surfaces defineExpose() entries on `wrapper.vm.$.exposed`.
+  return (wrapper.vm as { $: { exposed: ExposedShape } }).$.exposed
+}
+
+describe('AddPerformanceDialog — validation + submit', () => {
+  beforeEach(() => vi.clearAllMocks())
+  afterEach(() => vi.clearAllMocks())
+
+  function mountDialog() {
+    return mountWithVuexy(AddPerformanceDialog, {
+      props: {
+        modelValue: true,
+        orgId: 'org_1',
+        eventId: 'ev_1',
+        dayId: 'day_1',
+        stages: [stage],
+        engagements: [engagement as ArtistEngagement],
+      },
+      stubs: appStubs,
+    })
+  }
+
+  it('calls createPerformance mutation with the validated payload on happy path', async () => {
+    mocked.post.mockResolvedValueOnce({
+      data: {
+        success: true,
+        data: {
+          id: 'p1',
+          engagement_id: 'e1',
+          event_id: 'ev_1',
+          stage_id: 's1',
+          lane: 0,
+          lane_resolved: 0,
+          start_at: '2026-07-10T18:00:00.000Z',
+          end_at: '2026-07-10T19:00:00.000Z',
+          version: 0,
+          notes: null,
+          warnings: [],
+          created_at: '2026-07-10T18:00:00.000Z',
+          updated_at: '2026-07-10T18:00:00.000Z',
+          deleted_at: null,
+        },
+      },
+    })
+
+    const { wrapper } = mountDialog()
+    const exposed = getExposed(wrapper)
+
+    exposed.form.value.engagement_id = 'e1'
+    exposed.form.value.stage_id = 's1'
+    exposed.form.value.start_at = '2026-07-10 18:00:00'
+    exposed.form.value.end_at = '2026-07-10 19:00:00'
+    exposed.form.value.lane = 0
+    exposed.form.value.notes = ''
+
+    await exposed.submit()
+
+    expect(mocked.post).toHaveBeenCalledTimes(1)
+
+    const [url, body] = mocked.post.mock.calls[0]
+
+    expect(url).toContain('/events/ev_1/performances')
+    expect(body).toMatchObject({
+      engagement_id: 'e1',
+      event_id: 'day_1',
+      stage_id: 's1',
+      start_at: '2026-07-10 18:00:00',
+      end_at: '2026-07-10 19:00:00',
+    })
+  })
+
+  it('blocks submit when end_at is before start_at and surfaces an error on the field', async () => {
+    const { wrapper } = mountDialog()
+    const exposed = getExposed(wrapper)
+
+    exposed.form.value.engagement_id = 'e1'
+    exposed.form.value.stage_id = 's1'
+    exposed.form.value.start_at = '2026-07-10 19:00:00'
+    exposed.form.value.end_at = '2026-07-10 18:00:00'
+
+    await exposed.submit()
+
+    expect(mocked.post).not.toHaveBeenCalled()
+    expect(exposed.errors.value.end_at).toMatch(/Eindtijd/)
+  })
+
+  it('blocks submit when engagement_id is empty', async () => {
+    const { wrapper } = mountDialog()
+    const exposed = getExposed(wrapper)
+
+    exposed.form.value.engagement_id = ''
+    exposed.form.value.stage_id = 's1'
+    exposed.form.value.start_at = '2026-07-10 18:00:00'
+    exposed.form.value.end_at = '2026-07-10 19:00:00'
+
+    await exposed.submit()
+
+    expect(mocked.post).not.toHaveBeenCalled()
+    expect(exposed.errors.value.engagement_id).toBeTruthy()
+  })
+
+  it('emits update:modelValue=false when the cancel button is clicked', async () => {
+    const { wrapper } = mountDialog()
+
+    const cancelBtn = wrapper.findAll('button').find(b => b.text().includes('Annuleer'))
+
+    expect(cancelBtn).toBeDefined()
+    await cancelBtn!.trigger('click')
+
+    const closeEvents = (wrapper.emitted('update:modelValue') ?? []).filter(e => e[0] === false)
+
+    expect(closeEvents.length).toBeGreaterThanOrEqual(1)
+  })
+})