Add end-to-end tests for task modification and assignment features

- Implemented tests for editing penalty points and reward costs in `penalty-edit-points.spec.ts` and `reward-edit-cost.spec.ts`.
- Created detailed plans for task activation and assignment scenarios in `task-activated.plan.md` and `task-assignment.plan.md`.
- Added comprehensive test cases for modifying tasks, including editing points for chores, kindness acts, penalties, and rewards in `task-modified.plan.md`.
- Ensured all tests are isolated and run in serial mode to maintain state integrity.

frontend/vue-app/e2e/mode_parent/task-activation/penalty-activation.spec.ts

@@ -0,0 +1,173 @@
+// spec: e2e/plans/task-activated.plan.md
+
+import { test, expect, type APIRequestContext, type Locator, type Page } from '@playwright/test'
+
+const CHILD_NAME = 'ActivatePenaltyChild'
+const PEN_NAME = 'TriggerTestPenalty'
+const PEN_HELPER_NAME = 'TriggerPenaltyHelper'
+const PEN_POINTS = 20
+const INITIAL_POINTS = 50
+
+async function createChild(
+  request: APIRequestContext,
+  name: string,
+  points: number,
+): Promise<string> {
+  const pre = await request.get('/api/child/list')
+  for (const c of (await pre.json()).children ?? []) {
+    if (c.name === name) await request.delete(`/api/child/${c.id}`)
+  }
+  await request.put('/api/child/add', { data: { name, age: 8 } })
+  const list = await request.get('/api/child/list')
+  const id = (await list.json()).children?.find((c: any) => c.name === name)?.id ?? ''
+  if (points > 0) await request.put(`/api/child/${id}/edit`, { data: { points } })
+  return id
+}
+
+async function createTask(
+  request: APIRequestContext,
+  name: string,
+  type: 'chore' | 'kindness' | 'penalty',
+  points: number,
+): Promise<string> {
+  const pre = await request.get('/api/task/list')
+  for (const t of (await pre.json()).tasks ?? []) {
+    if (t.name === name) await request.delete(`/api/task/${t.id}`)
+  }
+  await request.put('/api/task/add', { data: { name, points, type } })
+  const list = await request.get('/api/task/list')
+  return (await list.json()).tasks?.find((t: any) => t.name === name)?.id ?? ''
+}
+
+async function getPoints(page: Page): Promise<number> {
+  const text = await page.locator('.points .value').textContent()
+  return parseInt(text?.trim() ?? '0', 10)
+}
+
+async function activateItem(itemCard: Locator): Promise<void> {
+  await itemCard.click()
+  await expect(itemCard).toHaveClass(/item-ready/, { timeout: 3000 })
+  await itemCard.click()
+}
+
+function penaltySection(page: Page): Locator {
+  return page.locator('.child-list-container').filter({
+    has: page.locator('h3', { hasText: 'Penalties' }),
+  })
+}
+
+test.describe('Penalty activation', () => {
+  test.describe.configure({ mode: 'serial' })
+
+  let childId = ''
+  let penId = ''
+  let penHelperId = ''
+
+  test.beforeAll(async ({ request }) => {
+    childId = await createChild(request, CHILD_NAME, INITIAL_POINTS)
+    penId = await createTask(request, PEN_NAME, 'penalty', PEN_POINTS)
+    penHelperId = await createTask(request, PEN_HELPER_NAME, 'penalty', PEN_POINTS)
+    await request.put(`/api/child/${childId}/set-tasks`, {
+      data: { task_ids: [penId, penHelperId], type: 'penalty' },
+    })
+  })
+
+  test.afterAll(async ({ request }) => {
+    if (childId) await request.delete(`/api/child/${childId}`)
+    if (penId) await request.delete(`/api/task/${penId}`)
+    if (penHelperId) await request.delete(`/api/task/${penHelperId}`)
+  })
+
+  test('Edit button appears on first penalty click', async ({ page }) => {
+    await page.goto(`/parent/${childId}`)
+    const card = penaltySection(page).locator('.item-card').filter({ hasText: PEN_NAME })
+    await card.waitFor({ state: 'visible' })
+
+    // Initially hidden
+    await expect(card.getByTitle('Edit custom value')).not.toBeVisible()
+
+    // First click: item enters ready state, edit button becomes visible
+    await card.click()
+    await expect(card).toHaveClass(/item-ready/, { timeout: 3000 })
+    await expect(card.getByTitle('Edit custom value')).toBeVisible()
+  })
+
+  test('Edit button disappears when clicking a different penalty card', async ({ page }) => {
+    await page.goto(`/parent/${childId}`)
+    const section = penaltySection(page)
+    const card = section.locator('.item-card').filter({ hasText: PEN_NAME })
+    const helperCard = section.locator('.item-card').filter({ hasText: PEN_HELPER_NAME })
+    await card.waitFor({ state: 'visible' })
+    await helperCard.waitFor({ state: 'visible' })
+
+    // First click on target card — edit button appears
+    await card.click()
+    await expect(card).toHaveClass(/item-ready/, { timeout: 3000 })
+    await expect(card.getByTitle('Edit custom value')).toBeVisible()
+
+    // Click on a different card — target's edit button disappears
+    await helperCard.click()
+    await expect(card.getByTitle('Edit custom value')).not.toBeVisible()
+  })
+
+  test('Cancel penalty confirmation — no points deducted', async ({ page }) => {
+    await page.goto(`/parent/${childId}`)
+    const card = penaltySection(page).locator('.item-card').filter({ hasText: PEN_NAME })
+    await card.waitFor({ state: 'visible' })
+
+    const before = await getPoints(page)
+
+    await activateItem(card)
+    await expect(page.getByRole('button', { name: 'Yes' })).toBeVisible()
+    await page.getByRole('button', { name: 'Cancel' }).click()
+
+    await expect(page.getByRole('button', { name: 'Yes' })).not.toBeVisible()
+    await expect(page.locator('.points .value')).toHaveText(String(before))
+  })
+
+  test('Confirm penalty activation — points deducted', async ({ page }) => {
+    // Starts at INITIAL_POINTS (50)
+    await page.goto(`/parent/${childId}`)
+    const card = penaltySection(page).locator('.item-card').filter({ hasText: PEN_NAME })
+    await card.waitFor({ state: 'visible' })
+
+    const before = await getPoints(page)
+
+    await activateItem(card)
+    await expect(page.getByRole('button', { name: 'Yes' })).toBeVisible()
+    await page.getByRole('button', { name: 'Yes' }).click()
+
+    // 50 - 20 = 30
+    await expect(page.locator('.points .value')).toHaveText(String(before - PEN_POINTS))
+  })
+
+  test('Penalty can be activated multiple times — points deducted again', async ({ page }) => {
+    // Starts at 30 after previous test
+    await page.goto(`/parent/${childId}`)
+    const card = penaltySection(page).locator('.item-card').filter({ hasText: PEN_NAME })
+    await card.waitFor({ state: 'visible' })
+
+    const before = await getPoints(page)
+
+    await activateItem(card)
+    await expect(page.getByRole('button', { name: 'Yes' })).toBeVisible()
+    await page.getByRole('button', { name: 'Yes' }).click()
+
+    // 30 - 20 = 10
+    await expect(page.locator('.points .value')).toHaveText(String(before - PEN_POINTS))
+  })
+
+  test('Points floor at 0 — penalty cannot make points negative', async ({ page }) => {
+    // Starts at 10 after previous test; penalty is 20 pts
+    await page.goto(`/parent/${childId}`)
+    const card = penaltySection(page).locator('.item-card').filter({ hasText: PEN_NAME })
+    await card.waitFor({ state: 'visible' })
+
+    await activateItem(card)
+    await expect(page.getByRole('button', { name: 'Yes' })).toBeVisible()
+    await page.getByRole('button', { name: 'Yes' }).click()
+
+    // 10 - 20 would be -10; app floors at 0
+    await expect(page.locator('.points .value')).toHaveText('0')
+  })
+})