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/scroll-and-flow.spec.ts

@@ -0,0 +1,194 @@
+// spec: e2e/plans/task-activated.plan.md
+// Tests for scrollable list flow and first-click scroll-to-center behavior.
+// 8 kindness items are assigned to a dedicated child so the list overflows
+// a narrow (480 px) viewport, reliably exercising the horizontal scroll path.
+
+import { test, expect, type APIRequestContext, type Locator } from '@playwright/test'
+
+/**
+ * Returns true if the element's bounding rect overlaps the current page viewport.
+ * Uses getBoundingClientRect() — reliable across all Playwright versions and
+ * correctly handles elements clipped by overflow scroll containers.
+ */
+async function isInViewport(locator: Locator): Promise<boolean> {
+  return locator.evaluate((el) => {
+    const rect = el.getBoundingClientRect()
+    return (
+      rect.bottom > 0 &&
+      rect.right > 0 &&
+      rect.top < (window.innerHeight || document.documentElement.clientHeight) &&
+      rect.left < (window.innerWidth || document.documentElement.clientWidth)
+    )
+  })
+}
+
+const CHILD_NAME = 'ScrollFlowChild'
+const ITEM_COUNT = 8
+const ITEM_NAMES = Array.from({ length: ITEM_COUNT }, (_, i) => `ScrollTestKindness${i + 1}`)
+const NARROW_VIEWPORT = { width: 480, height: 800 }
+
+// ── helpers ───────────────────────────────────────────────────────────────────
+
+async function createChild(request: APIRequestContext, name: string): Promise<string> {
+  const pre = await request.get('/api/child/list')
+  for (const c of (await pre.json()).children ?? []) {
+    if (c.name === name) await request.delete(`/api/child/${c.id}`)
+  }
+  await request.put('/api/child/add', { data: { name, age: 8 } })
+  const list = await request.get('/api/child/list')
+  return (await list.json()).children?.find((c: any) => c.name === name)?.id ?? ''
+}
+
+async function createTask(request: APIRequestContext, name: string): 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/${t.id}`)
+  }
+  await request.put('/api/task/add', { data: { name, points: 5, type: 'kindness' } })
+  const list = await request.get('/api/task/list')
+  return (await list.json()).tasks?.find((t: any) => t.name === name)?.id ?? ''
+}
+
+// ── tests ─────────────────────────────────────────────────────────────────────
+
+test.describe('Scroll and flow', () => {
+  test.describe.configure({ mode: 'serial' })
+
+  let childId = ''
+  const taskIds: string[] = []
+
+  test.beforeAll(async ({ request }) => {
+    childId = await createChild(request, CHILD_NAME)
+    for (const name of ITEM_NAMES) {
+      taskIds.push(await createTask(request, name))
+    }
+    await request.put(`/api/child/${childId}/set-tasks`, {
+      data: { task_ids: taskIds, type: 'kindness' },
+    })
+  })
+
+  test.afterAll(async ({ request }) => {
+    if (childId) await request.delete(`/api/child/${childId}`)
+    for (const id of taskIds) await request.delete(`/api/task/${id}`)
+    taskIds.length = 0
+  })
+
+  test('Kindness list is horizontally scrollable when many items are assigned', async ({
+    page,
+  }) => {
+    await page.setViewportSize(NARROW_VIEWPORT)
+    await page.goto(`/parent/${childId}`)
+
+    const scrollWrapper = page
+      .locator('.child-list-container')
+      .filter({ has: page.locator('h3', { hasText: 'Kindness Acts' }) })
+      .locator('.scroll-wrapper')
+    await scrollWrapper.waitFor({ state: 'visible' })
+
+    // Total content width (8 × 140 px + 7 × 12 px gaps ≈ 1204 px) must exceed container width
+    const isOverflowing = await scrollWrapper.evaluate(
+      (el: HTMLElement) => el.scrollWidth > el.clientWidth,
+    )
+    expect(isOverflowing).toBe(true)
+
+    // The last card in DOM order is outside the 480 px viewport at scrollLeft=0
+    const section = page
+      .locator('.child-list-container')
+      .filter({ has: page.locator('h3', { hasText: 'Kindness Acts' }) })
+    const lastCard = section.locator('.item-card').last()
+
+    expect(await isInViewport(lastCard)).toBe(false)
+  })
+
+  test('Scrolling the list reveals hidden items', async ({ page }) => {
+    await page.setViewportSize(NARROW_VIEWPORT)
+    await page.goto(`/parent/${childId}`)
+
+    const section = page
+      .locator('.child-list-container')
+      .filter({ has: page.locator('h3', { hasText: 'Kindness Acts' }) })
+    const scrollWrapper = section.locator('.scroll-wrapper')
+    await scrollWrapper.waitFor({ state: 'visible' })
+
+    // Use DOM-order first/last — independent of API return order
+    const firstCard = section.locator('.item-card').first()
+    const lastCard = section.locator('.item-card').last()
+
+    // Initially: first item is in viewport, last item is scrolled off to the right
+    expect(await isInViewport(firstCard)).toBe(true)
+    expect(await isInViewport(lastCard)).toBe(false)
+
+    // Programmatically scroll to the end — override smooth-scroll so position is immediate
+    await scrollWrapper.evaluate((el: HTMLElement) => {
+      el.style.scrollBehavior = 'auto'
+      el.scrollLeft = el.scrollWidth
+    })
+    await page.waitForTimeout(100)
+
+    // Last item is now visible; first item has scrolled off to the left
+    expect(await isInViewport(lastCard)).toBe(true)
+    expect(await isInViewport(firstCard)).toBe(false)
+  })
+
+  test('First click on an off-screen item scrolls it into view and marks it ready', async ({
+    page,
+  }) => {
+    await page.setViewportSize(NARROW_VIEWPORT)
+    await page.goto(`/parent/${childId}`)
+
+    const section = page
+      .locator('.child-list-container')
+      .filter({ has: page.locator('h3', { hasText: 'Kindness Acts' }) })
+    const scrollWrapper = section.locator('.scroll-wrapper')
+    await scrollWrapper.waitFor({ state: 'visible' })
+
+    // The last item in DOM order is definitely off-screen at scrollLeft=0 on a 480 px viewport
+    const lastCard = section.locator('.item-card').last()
+    expect(await isInViewport(lastCard)).toBe(false)
+
+    // force: true is required because the element's bounding-box center is outside
+    // the page viewport — that is exactly the condition we are testing (scroll-to-center).
+    await lastCard.click({ force: true })
+
+    // The first-click handler runs centerItem() then emits item-ready
+    await expect(lastCard).toHaveClass(/item-ready/, { timeout: 5000 })
+
+    // Wait for the smooth-scroll animation to settle
+    await page.waitForTimeout(800)
+
+    // After centering, the item must be visible within the 480 px viewport
+    expect(await isInViewport(lastCard)).toBe(true)
+  })
+
+  test('Scrolling does not prevent first-click centering on a partially visible item', async ({
+    page,
+  }) => {
+    await page.setViewportSize(NARROW_VIEWPORT)
+    await page.goto(`/parent/${childId}`)
+
+    const section = page
+      .locator('.child-list-container')
+      .filter({ has: page.locator('h3', { hasText: 'Kindness Acts' }) })
+    const scrollWrapper = section.locator('.scroll-wrapper')
+    await scrollWrapper.waitFor({ state: 'visible' })
+
+    // Scroll to the middle — override smooth-scroll so position is immediate
+    await scrollWrapper.evaluate((el: HTMLElement) => {
+      el.style.scrollBehavior = 'auto'
+      el.scrollLeft = Math.floor(el.scrollWidth / 2)
+    })
+    await page.waitForTimeout(100)
+
+    // The first item in DOM order is now off-screen to the left after scrolling to the middle
+    const firstCard = section.locator('.item-card').first()
+    expect(await isInViewport(firstCard)).toBe(false)
+
+    // Click the first item (force: true because its center is left of the viewport)
+    await firstCard.click({ force: true })
+    await expect(firstCard).toHaveClass(/item-ready/, { timeout: 5000 })
+    await page.waitForTimeout(800)
+
+    // First item should now be centered and in the viewport
+    expect(await isInViewport(firstCard)).toBe(true)
+  })
+})