Take the time off together, in long stretches

A season preset in a two-parent household now means both parents, not
either one — being off together is the point of the period.

Within such a period the planner used to pick whoever had the most
parental-benefit days left, date by date, so spending kept moving the
lead and the funding flipped almost daily. Six weeks came out as a
patchwork that costs nothing to hold but a great deal to request. The
payer is now chosen once per half of the window, reusing the same split
the swap strategy already uses: one parent on parental benefit while the
other takes vacation, then they change over. Both are still off every
day, and if one runs out mid-stretch the roles swap for the rest rather
than day by day.

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

frontend/src/pages/Calendar.test.tsx

@@ -850,6 +850,43 @@ describe('Calendar', () => {
       await waitFor(() => expect(sync).toHaveBeenCalled())
     })
 
+    it('defaults a solo household preset to "either" parent', async () => {
+      const created = makeLeaveWish({ id: 'lw-preset' })
+      const add = vi.fn().mockResolvedValue(created)
+      const sync = vi.fn().mockResolvedValue(makePlanSyncResponse())
+      vi.mocked(useWorkspaceMembers).mockReturnValue(
+        makeWorkspaceMembersResult({ data: [makePersonalData({ uuid: 'pd-a', name: 'Förälder A' })] }),
+      )
+      vi.mocked(useLeaveWishes).mockReturnValue(makeLeaveWishesResult({ add, data: [] }))
+      vi.mocked(usePlanSync).mockReturnValue(makePlanSyncResult({ sync }))
+
+      render(<Calendar />)
+      fireEvent.click(screen.getByTestId('preset-click'))
+
+      await waitFor(() => expect(add).toHaveBeenCalledWith(expect.objectContaining({ parentMode: 'either' })))
+    })
+
+    it('defaults a two-parent household preset to "both" parents', async () => {
+      const created = makeLeaveWish({ id: 'lw-preset' })
+      const add = vi.fn().mockResolvedValue(created)
+      const sync = vi.fn().mockResolvedValue(makePlanSyncResponse())
+      vi.mocked(useWorkspaceMembers).mockReturnValue(
+        makeWorkspaceMembersResult({
+          data: [
+            makePersonalData({ uuid: 'pd-a', name: 'Förälder A' }),
+            makePersonalData({ uuid: 'pd-b', name: 'Förälder B' }),
+          ],
+        }),
+      )
+      vi.mocked(useLeaveWishes).mockReturnValue(makeLeaveWishesResult({ add, data: [] }))
+      vi.mocked(usePlanSync).mockReturnValue(makePlanSyncResult({ sync }))
+
+      render(<Calendar />)
+      fireEvent.click(screen.getByTestId('preset-click'))
+
+      await waitFor(() => expect(add).toHaveBeenCalledWith(expect.objectContaining({ parentMode: 'both' })))
+    })
+
     it('navigates the month view to the resolved placement and flashes the band', async () => {
       const created = makeLeaveWish({ id: 'lw-preset' })
       const add = vi.fn().mockResolvedValue(created)