Let a day removed from a period stay removed

Taking one day out of a period the planner placed did nothing that
lasted: the period still asked for a full week, so the next sync put the
day straight back. The option was disabled rather than lying about it.

A removed day is now recorded as its own thing — no leave for this
parent, this child, this date — and the planner honours it on every
later sync. It is kept apart from the working-day overrides, which
answer a different question about the calendar rather than about the
plan.

The day belongs to the parent whose band was clicked, so removing one
parent's day leaves their partner's alone; where both parents were to be
off on one funding arrangement, the partner is simply funded on their
own instead. A removed day shortens what the period is asking for rather
than counting as a day the plan failed to find, so the advice about
closing a shortfall does not start arguing for a day nobody wants.

Nothing is removed without a way back: the toast undoes it, and the day
itself is marked in the calendar and offers to restore.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ei7gCZzdd751uZtPzb1Pep

frontend/e2e/tests/drag-create-delete.spec.ts

@@ -176,13 +176,14 @@ test('a drag saved without opening Advanced creates a planner-funded wish, and t
 
   await expect(wishBand.first()).toBeVisible()
 
-  // Open the wish-linked band. Its own three-way remove: "this day" cannot
-  // be expressed for a wish (it would just reappear on the next sync) and
-  // is disabled; "this period" on a standalone (non-repeating) wish — one
-  // row, no series — removes the whole thing, same as "every year".
+  // Open the wish-linked band. Its own three-way remove: "this day" now
+  // works on a planner-placed day too (the removal is recorded as a
+  // `PlannedDayExclusion` — see the next test); "this period" on a
+  // standalone (non-repeating) wish — one row, no series — removes the whole
+  // thing, same as "every year".
   await wishBand.first().click()
   await expect(page.getByTestId('period-popover__content')).toBeVisible()
-  await expect(page.getByTestId('period-delete-day-button')).toBeDisabled()
+  await expect(page.getByTestId('period-delete-day-button')).toBeEnabled()
 
   await page.getByTestId('period-delete-year-button').click()
   await expect(page.getByTestId('period-delete-confirm')).toBeVisible()
@@ -193,3 +194,54 @@ test('a drag saved without opening Advanced creates a planner-funded wish, and t
   await goToCalendarMonth(page, month)
   await expect(page.locator('[data-testid^="calendar-band-wish:"]')).toHaveCount(0)
 })
+
+test('removing a single day out of a planner-placed period keeps it removed across syncs', async ({
+  page,
+}) => {
+  // The user's requirement: "removing a single day should stay permanent.
+  // Even if it's an auto added period day." The wish behind the band still
+  // asks for the whole window, so without a stored `PlannedDayExclusion` the
+  // next `POST /api/plan/sync` — which the calendar runs on every load —
+  // would simply put the day back.
+  await registerAndReachOnboarding(page, uniqueEmail('remove-day'), 'Robin Testsson')
+  await fillChildStep(page, 'Nova')
+  await continueSoloAndSkipBalances(page)
+
+  const { month, dates } = targetRange()
+  await goToCalendarMonth(page, month)
+
+  const wishBand = page.locator('[data-testid^="calendar-band-wish:"]')
+  await expect(wishBand).toHaveCount(0)
+
+  await dragSelectDates(page, dates)
+  await expect(page.getByTestId('modal-title')).toHaveText('Planera 3 dagar')
+  await page.getByTestId('save-button').click()
+  await expect(page.getByTestId('planned-day-modal__content')).not.toBeVisible()
+  await expect(wishBand.first()).toBeVisible()
+
+  // Clicking the band itself targets its first placed date; clicking one of
+  // its day slots would target that date instead (see CalendarWeek's
+  // `clickedDate`). Either way the popover's "this day" removes exactly one.
+  await wishBand.first().click()
+  await expect(page.getByTestId('period-popover__content')).toBeVisible()
+  await page.getByTestId('period-delete-day-button').click()
+  await expect(page.getByTestId('period-delete-confirm')).toBeVisible()
+  await page.getByTestId('period-delete-confirm-button').click()
+  await expect(page.getByTestId('period-popover__overlay')).not.toBeVisible()
+
+  // There is a way back, offered immediately.
+  await expect(page.getByTestId('calendar-toast-undo')).toBeVisible()
+
+  // The removed date is marked rather than silently empty — a hole in an
+  // otherwise-funded week would read as a planner bug.
+  await expect(page.getByTestId('calendar-day-excluded-badge')).toHaveCount(1)
+  // The rest of the period survives: this removed one day, not the wish.
+  await expect(wishBand.first()).toBeVisible()
+
+  // The real assertion: a reload re-syncs the plan from the wish, and the
+  // day must still be gone afterwards.
+  await page.reload()
+  await goToCalendarMonth(page, month)
+  await expect(page.getByTestId('calendar-day-excluded-badge')).toHaveCount(1)
+  await expect(page.locator('[data-testid^="calendar-band-wish:"]').first()).toBeVisible()
+})