fix(bookkeeping): a following year's own IB no longer blocks nollställ, and a re-dated räkenskapsår gets the right name (#2286)

Customer report (Aisen & Adison AB, 2026-09-03): Fortnox years 2024-2026
imported first, then the first year 2022/2023 backfilled. Two bugs surfaced.

1. The backfilled year was saved as "Räkenskapsår 2027": CreatePeriodDialog
   seeds the next forward year and kept that name when the user re-dated the
   form. The name now follows the typed dates until the user edits the name
   (fiscalYearName exported from suggest-fiscal-period).

2. Nollställ of the backfilled year was refused with next_year_dependency
   because 2024 carried an opening-balance verifikat. Any IB in the next year
   counted as reliance, so a backfilled year could never be reset, while a
   next year WITHOUT an IB (whose balansrapport really rolls from this year)
   was allowed. Migration 20260904163000 redefines fiscal_year_reset_snapshot:
   the block fires only when the next year is locked, closed or has its own
   closing entry; a bokslut-generated IB is still refused via this year's
   closing_entry_id (year_end_state). The snapshot returns next_period
   {id, name, has_opening_balances} and the dialog states that the following
   year's IB stays as it is.

pg-real: reset-fiscal-year.pg.test.ts pins the narrowed guard (closed next
year, next year with closing entry, next year with its own IB survives the
reset untouched).

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

components/bookkeeping/CreatePeriodDialog.tsx

@@ -16,7 +16,7 @@ import { Label } from '@/components/ui/label'
 import { AttnLine } from '@/components/ui/attn-line'
 import { useToast } from '@/components/ui/use-toast'
 import { Loader2 } from 'lucide-react'
-import { computeSuggestedPeriod } from '@/lib/bookkeeping/suggest-fiscal-period'
+import { computeSuggestedPeriod, fiscalYearName } from '@/lib/bookkeeping/suggest-fiscal-period'
 import { fiscalPeriodAdvisoryText } from '@/lib/bookkeeping/fiscal-period-warnings'
 import type { FiscalPeriod } from '@/types'
 import { invalidateReferenceData } from '@/lib/reference-data/invalidate'
@@ -61,6 +61,11 @@ export default function CreatePeriodDialog({ open, onOpenChange, entryDate, peri
   const suggested = useMemo(() => computeSuggestedPeriod(entryDate, periods), [entryDate, periods])
 
   const [name, setName] = useState(suggested.name)
+  // The name follows the dates until the user types a name of their own.
+  // Without this the seed suggestion (the next forward year, e.g.
+  // "Räkenskapsår 2027") survived the user re-dating the form to a backfilled
+  // first year and was saved verbatim.
+  const [nameEdited, setNameEdited] = useState(false)
   const [periodStart, setPeriodStart] = useState(suggested.period_start)
   const [periodEnd, setPeriodEnd] = useState(suggested.period_end)
   const [isSubmitting, setIsSubmitting] = useState(false)
@@ -72,12 +77,21 @@ export default function CreatePeriodDialog({ open, onOpenChange, entryDate, peri
   const [lastSuggested, setLastSuggested] = useState(suggested)
   if (suggested.name !== lastSuggested.name || suggested.period_start !== lastSuggested.period_start) {
     setName(suggested.name)
+    setNameEdited(false)
     setPeriodStart(suggested.period_start)
     setPeriodEnd(suggested.period_end)
     setLastSuggested(suggested)
     setCreated(null)
   }
 
+  // A date input yields '' while incomplete and a full YYYY-MM-DD otherwise:
+  // only derive a name once both ends are known.
+  const updateDates = (start: string, end: string) => {
+    setPeriodStart(start)
+    setPeriodEnd(end)
+    if (!nameEdited && start && end) setName(fiscalYearName(start, end))
+  }
+
   // Close, and refetch in the parent if this session created a period. The
   // refetch is deferred to here on the advisory path on purpose: it swaps the
   // `periods` prop, which resets the form above, and that would pull the
@@ -175,16 +189,23 @@ export default function CreatePeriodDialog({ open, onOpenChange, entryDate, peri
             <div className="space-y-3">
               <div>
                 <Label>Namn</Label>
-                <Input value={name} onChange={(e) => setName(e.target.value)} className="mt-1" />
+                <Input
+                  value={name}
+                  onChange={(e) => {
+                    setName(e.target.value)
+                    setNameEdited(true)
+                  }}
+                  className="mt-1"
+                />
               </div>
               <div className="grid grid-cols-2 gap-3">
                 <div>
                   <Label>Startdatum</Label>
-                  <Input type="date" value={periodStart} onChange={(e) => setPeriodStart(e.target.value)} className="mt-1" />
+                  <Input type="date" value={periodStart} onChange={(e) => updateDates(e.target.value, periodEnd)} className="mt-1" />
                 </div>
                 <div>
                   <Label>Slutdatum</Label>
-                  <Input type="date" value={periodEnd} onChange={(e) => setPeriodEnd(e.target.value)} className="mt-1" />
+                  <Input type="date" value={periodEnd} onChange={(e) => updateDates(periodStart, e.target.value)} className="mt-1" />
                 </div>
               </div>
             </div>

components/settings/FiscalYearResetDialog.tsx

@@ -242,6 +242,11 @@ export function FiscalYearResetDialog({
               <p className="mt-2 text-xs text-muted-foreground">
                 {t('fy_reset_documents_note')}
               </p>
+              {eligibility.next_period?.has_opening_balances ? (
+                <p className="mt-2 text-xs text-muted-foreground">
+                  {t('fy_reset_next_year_ib_note', { name: eligibility.next_period.name })}
+                </p>
+              ) : null}
             </div>
 
             {eligibility.eligible ? (