feat(invoices): ROT/RUT payout file dialog and file guards (#1380)

* feat(invoices): ROT/RUT payout file dialog and file guards

Rebuild the UI for the existing headless HUS V6 payout-file flow
(demanded via #789): a dialog on the invoices page to pick eligible
paid ROT/RUT invoices, generate the XML, download it and track
request status. Adds file-level guards from the Skatteverket spec:
future payment dates blocked, one file per payment year, max 100
cases per file, with per-invoice blocker messages.

Submission stays manual (upload + sign in the SKV e-service);
no direct submission API exists.

Fixes #789

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(invoices): compute rot-rut gating date in Europe/Stockholm

The candidate and begäran date defaults used the UTC calendar day,
which near midnight Swedish time could wrongly block or admit an
invoice via FUTURE_PAYMENT_DATE and shift the 31 January deadline
warning. Use getSwedishLocalDate() like the bookkeeping engine.
Raised by the Swedish compliance review on PR #1380.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

app/(dashboard)/invoices/page.tsx

@@ -23,7 +23,7 @@ import { formatCurrency, formatDate } from '@/lib/utils'
 import { cn } from '@/lib/utils'
 import { invoiceDisplayNumber } from '@/lib/invoices/display'
 import { getDisplayTotal } from '@/lib/invoices/rounding'
-import { Plus, Search, ReceiptText, Repeat, FileInput } from 'lucide-react'
+import { Plus, Search, ReceiptText, Repeat, FileInput, FileDown } from 'lucide-react'
 import { EmptyInvoices } from '@/components/ui/empty-state'
 import { useCompany } from '@/contexts/CompanyContext'
 import { useCanWrite } from '@/lib/hooks/use-can-write'
@@ -50,6 +50,10 @@ const NewInvoiceDialog = dynamic(
   { loading: NewInvoiceDialogLoading },
 )
 
+const RotRutPayoutDialog = dynamic(
+  () => import('@/components/invoices/RotRutPayoutDialog'),
+)
+
 const INITIAL_VISIBLE_ROWS = 100
 
 const CREATE_MODES = ['faktura', 'aterkommande', 'sjalvfaktura'] as const
@@ -116,9 +120,12 @@ export default function InvoicesPage() {
   const copyFromId = searchParams.get('copy')
   const showNewInvoice = searchParams.has('new') || copyFromId !== null
   const openSelfBilled = searchParams.has('self')
+  const showRotRutPayout = searchParams.has('rot-rut')
   const closeNewInvoice = () => router.replace('/invoices', { scroll: false })
   const openNewInvoice = () => router.push('/invoices?new=1', { scroll: false })
   const openNewSelfBilled = () => router.push('/invoices?new=1&self=1', { scroll: false })
+  const closeRotRutPayout = () => router.replace('/invoices', { scroll: false })
+  const openRotRutPayout = () => router.push('/invoices?rot-rut=1', { scroll: false })
 
   async function fetchInvoices() {
     if (!company) return
@@ -251,15 +258,27 @@ export default function InvoicesPage() {
 
   return (
     <div className="space-y-8">
-      {/* Page header (concept scene 15): title + Ny faktura split button */}
+      {/* Page header (concept scene 15): title + invoice actions */}
       <div className="flex flex-col gap-4 sm:flex-row sm:items-center sm:justify-between">
         <h1 className="font-display text-2xl leading-8 tracking-tight">{t('title')}</h1>
-        <SplitButton
-          key={uiStateLoaded ? 'loaded' : 'initial'}
-          persistKey="invoices"
-          initialModeKey={resolveInitialMode(uiState, 'invoices', CREATE_MODES, 'faktura')}
-          options={createOptions}
-        />
+        <div className="flex flex-wrap items-center gap-2">
+          <Button
+            type="button"
+            variant="outline"
+            onClick={openRotRutPayout}
+            disabled={!canWrite}
+            title={!canWrite ? t('viewer_disabled_tooltip') : undefined}
+          >
+            <FileDown className="mr-2 h-4 w-4" />
+            {t('rot_rut_payout_action')}
+          </Button>
+          <SplitButton
+            key={uiStateLoaded ? 'loaded' : 'initial'}
+            persistKey="invoices"
+            initialModeKey={resolveInitialMode(uiState, 'invoices', CREATE_MODES, 'faktura')}
+            options={createOptions}
+          />
+        </div>
       </div>
 
       {/* Toolbar: one status chip-picker (founder direction: the status
@@ -452,6 +471,15 @@ export default function InvoicesPage() {
           }}
         />
       )}
+      {showRotRutPayout && (
+        <RotRutPayoutDialog
+          open
+          canWrite={canWrite}
+          onOpenChange={(open) => {
+            if (!open) closeRotRutPayout()
+          }}
+        />
+      )}
     </div>
   )
 }

app/api/rot-rut/__tests__/routes.test.ts

@@ -232,6 +232,36 @@ describe('POST /api/rot-rut/payout-file', () => {
     expect(body.error.code).toBe('ROT_RUT_INVOICES_BLOCKED')
   })
 
+  it('rejects a file that mixes payment years', async () => {
+    const otherInvoiceId = '33333333-3333-4333-8333-333333333333'
+    enqueue({
+      data: [
+        makePaidRotInvoice(),
+        makePaidRotInvoice({
+          id: otherInvoiceId,
+          invoice_number: 'F-2025',
+          paid_at: '2025-12-30T10:00:00Z',
+        }),
+      ],
+    })
+
+    const response = await payoutFilePOST(
+      createMockRequest('/api/rot-rut/payout-file', {
+        method: 'POST',
+        body: { deduction_type: 'rot', invoice_ids: [INVOICE_ID, otherInvoiceId] },
+      }),
+    )
+    const { status, body } = await parseJsonResponse<{
+      error: { code: string; details?: { blockers: Array<{ code: string }> } }
+    }>(response)
+
+    expect(status).toBe(400)
+    expect(body.error.code).toBe('ROT_RUT_INVOICES_BLOCKED')
+    expect(body.error.details?.blockers).toEqual([
+      expect.objectContaining({ invoice_id: otherInvoiceId, code: 'MIXED_PAYMENT_YEARS' }),
+    ])
+  })
+
   it('returns 404 when an invoice id does not belong to the company', async () => {
     enqueue({ data: [] })
     const response = await payoutFilePOST(