fix(supplier-invoices): reverse credit notes on paid kontantmetoden invoices (#1430)

Under kontantmetoden the credit flow skipped the reversing verifikat
entirely, gated on accounting_method === 'accrual' in all three surfaces
(dashboard route, v1 route, pending-operations commit).

That is right only while the original is still UNPAID: nothing reached the
ledger, so there is no entry to reverse and recognition waits for cash. But
a PAID original was already booked by its payment verifikat (expense +
2641 ingaende moms). Crediting it marked the invoice 'credited' with zero
accounting trace, leaving both the cost and the moms deduction overstated
and nothing to link a later refund back to.

Adds supplierCreditNoteNeedsJournalEntry(), the mirror of the customer
side's creditNoteNeedsJournalEntry(): reverse whenever the original
actually reached the ledger, whatever the configured method.
createSupplierCreditNoteEntry's existing shape already suits the cash case,
the 2440 debit leaves a claim on the supplier that the refund clears, just
as the customer side leaves a 1510 credit for a refund owed.

The v1 route's GDPR-minimised projection dropped exactly the booked-ness
columns this needs; they are restored with a comment explaining why, since
status alone misses a part-paid-but-booked original (rows predating #1413).

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

DECISIONS.md

@@ -802,3 +802,4 @@ One line per decision: `[YYYY-MM-DD] <decision>: <why>`. Appended by agents and
 [2026-08-06] Session replay masking narrowed from mask-everything to pattern-based (founder-approved): fully masked replays were wall-to-wall asterisks and useless for support debugging. lib/analytics/replay-masking.ts masks currency-shaped text, person-/organisationsnummer (text and typed input) and password inputs; data-ph-mask still force-masks tagged PII, data-ph-unmask stays honored for chrome, and everything else including typed input is now visible in replays. Privacy policy and RoPA updated in the same change; supersedes the 2026-07-27 maskTextSelector '*' decision.
 [2026-08-06] ROT/RUT payout strings were placed in the invoice_editor namespace while RotRutPayoutDialog and the invoices page read useTranslations('invoices'), so all 44 labels rendered as raw "invoices.rot_rut_*" key paths in production since #1380. Moved the keys to invoices rather than repointing the components, since the dialog belongs to the invoice list, not the editor. Message files are edited textually, never via JSON.parse/stringify: they contain duplicate keys a round trip would silently drop. Same bug class fixed in TemplateBookDialog (bookkeeping) and Correction/StrikeLines dialogs (journal_detail) by adding the strings to the namespace each component reads, matching the existing precedent that toast_posted_* is duplicated across journal_list and journal_detail. Added i18n/__tests__/message-keys.test.ts, which resolves every literal t() key against both locales: next-intl has no build-time check and fails by rendering the key path, so nothing caught this before users did.
 [2026-08-06] The ROT/RUT payout button is hidden from the invoices header unless the company has an invoice with deduction_total > 0 or rot_rut_enabled is on in tax settings. ROT/RUT concerns only companies selling eligible work to consumers, and a payout can never precede the invoice that created the claim, so the derived signal cannot hide the action from someone who needs it. Read from the company_settings row the page already fetches for ore_rounding (no extra round trip); deliberately not scoped to the fiscal-year filter, since a begäran is claimed the year after payment. ?rot-rut=1 still opens the dialog, so the feature is hidden, not removed.
+[2026-08-06] Supplier credit notes under kontantmetoden now reverse when the ORIGINAL was already booked (paid), not only under faktureringsmetoden: skipping left the expense and the 2641 ingaende moms deduction overstated with no accounting trace. Mirrors the customer-side creditNoteNeedsJournalEntry(). The v1 route's GDPR-minimised projection had to re-add registration_journal_entry_id/payment_journal_entry_id/paid_at/paid_amount: status alone misses a part-paid-but-booked original.

app/api/supplier-invoices/[id]/credit/__tests__/route.test.ts

@@ -158,4 +158,60 @@ describe('POST /api/supplier-invoices/[id]/credit', () => {
       'Leverantör AB',
     )
   })
+  it('skips the reversing entry under kontantmetoden while the original is unpaid', async () => {
+    // Nothing reached the ledger at registration, so there is no entry to
+    // reverse: recognition correctly waits for the refund.
+    const creditNote = makeSupplierInvoice({
+      id: 'credit-1',
+      is_credit_note: true,
+      credited_invoice_id: 'invoice-1',
+    })
+    enqueueMany([
+      { data: { ...original, status: 'registered', paid_amount: 0, paid_at: null, payment_journal_entry_id: null, registration_journal_entry_id: null }, error: null },
+      { data: 2, error: null },
+      { data: creditNote, error: null },
+      { data: null, error: null },
+      { data: { accounting_method: 'cash' }, error: null },
+      { data: null, error: null },
+    ])
+
+    const response = await POST(
+      createMockRequest('/api/supplier-invoices/invoice-1/credit', { method: 'POST' }),
+      createMockRouteParams({ id: 'invoice-1' }),
+    )
+    const { status } = await parseJsonResponse(response)
+
+    expect(status).toBe(200)
+    expect(createCreditEntryMock).not.toHaveBeenCalled()
+  })
+
+  it('reverses under kontantmetoden once the payment already booked the expense', async () => {
+    // The payment verifikat booked expense + 2641 ingående moms. Skipping the
+    // reversal here would leave both the cost and the moms deduction
+    // overstated for as long as the credit stands.
+    const creditNote = makeSupplierInvoice({
+      id: 'credit-1',
+      is_credit_note: true,
+      credited_invoice_id: 'invoice-1',
+    })
+    enqueueMany([
+      { data: { ...original, status: 'paid', paid_amount: 1250, paid_at: '2026-03-12', payment_journal_entry_id: 'je-payment' }, error: null },
+      { data: 2, error: null },
+      { data: creditNote, error: null },
+      { data: null, error: null },
+      { data: { accounting_method: 'cash' }, error: null },
+      { data: null, error: null },
+      { data: null, error: null },
+    ])
+    createCreditEntryMock.mockResolvedValue({ id: 'journal-1' })
+
+    const response = await POST(
+      createMockRequest('/api/supplier-invoices/invoice-1/credit', { method: 'POST' }),
+      createMockRouteParams({ id: 'invoice-1' }),
+    )
+    const { status } = await parseJsonResponse(response)
+
+    expect(status).toBe(200)
+    expect(createCreditEntryMock).toHaveBeenCalledTimes(1)
+  })
 })

app/api/supplier-invoices/[id]/credit/route.ts

@@ -2,6 +2,7 @@ import { NextResponse } from 'next/server'
 import { eventBus } from '@/lib/events'
 import { ensureInitialized } from '@/lib/init'
 import { createSupplierCreditNoteEntry } from '@/lib/bookkeeping/supplier-invoice-entries'
+import { supplierCreditNoteNeedsJournalEntry } from '@/lib/bookkeeping/booking-mode'
 import { cancelSchedulesForSource } from '@/lib/bookkeeping/accruals/service'
 import { isBookkeepingError } from '@/lib/bookkeeping/errors'
 import { withRouteContext } from '@/lib/api/with-route-context'
@@ -106,10 +107,13 @@ export const POST = withRouteContext(
 
     const accountingMethod = (settings?.accounting_method as AccountingMethod) || 'accrual'
 
-    // Cash method: skip, no original registration entry to reverse;
-    // recognition is deferred until refund.
+    // Kontantmetoden skips only while the original is still UNPAID: nothing
+    // reached the ledger, so there is nothing to reverse and recognition
+    // rightly waits for cash. A PAID original was already booked by its
+    // payment verifikat (expense + 2641 ingående moms), and leaving that
+    // un-reversed overstates both the cost and the moms deduction.
     let journalEntryId: string | null = null
-    if (accountingMethod === 'accrual') {
+    if (supplierCreditNoteNeedsJournalEntry(accountingMethod, original)) {
       try {
         // Pass the ORIGINAL items: deferred lines carry their periodisering
         // fields there, so the credit entry reverses against the same 17xx

app/api/v1/companies/[companyId]/supplier-invoices/[id]/credit/route.ts

@@ -25,6 +25,7 @@ import { withApiV1 } from '@/lib/api/v1/with-api-v1'
 import { v1ErrorResponse, v1ErrorResponseFromCode } from '@/lib/api/v1/errors'
 import { checkPeriodLock } from '@/lib/api/v1/check-period-lock'
 import { createSupplierCreditNoteEntry } from '@/lib/bookkeeping/supplier-invoice-entries'
+import { supplierCreditNoteNeedsJournalEntry } from '@/lib/bookkeeping/booking-mode'
 import { reverseEntry } from '@/lib/bookkeeping/engine'
 import { isBookkeepingError } from '@/lib/bookkeeping/errors'
 import { eventBus } from '@/lib/events'
@@ -47,18 +48,25 @@ const SI_RESPONSE_COLUMNS =
 // flow are projected. `user_id` and `company_id` were dropped earlier; this
 // round drops `notes` (the original SI's free-text notes are never copied
 // onto the credit note and never inspected) plus several housekeeping
-// fields (`paid_at`, `payment_journal_entry_id`, `transaction_id`,
-// `document_id`, `payment_reference`, `paid_amount`, `delivery_date`,
-// `received_date`, `is_credit_note`, `reversed_at`, `created_at`,
-// `updated_at`) that the credit handler never reads. SEK-conversion fields
-// (`subtotal_sek` / `vat_amount_sek` / `total_sek`) ARE read: they're
-// copied verbatim onto the credit-note row so the 2440 reversal nets
-// correctly.
+// fields (`transaction_id`, `document_id`, `payment_reference`,
+// `delivery_date`, `received_date`, `is_credit_note`, `reversed_at`,
+// `created_at`, `updated_at`) that the credit handler never reads. SEK-
+// conversion fields (`subtotal_sek` / `vat_amount_sek` / `total_sek`) ARE
+// read: they're copied verbatim onto the credit-note row so the 2440
+// reversal nets correctly.
+//
+// `registration_journal_entry_id`, `payment_journal_entry_id`, `paid_at` and
+// `paid_amount` were dropped in that round but are read again now: they are
+// the booked-ness signals supplierCreditNoteNeedsJournalEntry() needs to
+// decide whether a kontantmetoden credit note must reverse an entry the
+// payment already posted. `status` alone is too weak, it misses a
+// part-paid-but-booked original (rows predating the #1413 guard).
 const SI_FULL_COLUMNS = `
   id, supplier_id, supplier_invoice_number, invoice_date, status,
   currency, exchange_rate,
   subtotal, subtotal_sek, vat_amount, vat_amount_sek, total, total_sek,
   vat_treatment, reverse_charge, remaining_amount,
+  registration_journal_entry_id, payment_journal_entry_id, paid_at, paid_amount,
   is_credit_note, credited_invoice_id, arrival_number, default_dimensions,
   supplier:suppliers(id, name, supplier_type),
   items:supplier_invoice_items(id, sort_order, description, quantity, unit, unit_price, line_total, account_number, vat_code, vat_rate, vat_amount, reverse_charge_rate, dimensions)
@@ -154,6 +162,10 @@ export const POST = withApiV1<{ params: Promise<{ companyId: string; id: string
       reverse_charge: boolean
       remaining_amount: number
       paid_amount: number
+      // Booked-ness signals for supplierCreditNoteNeedsJournalEntry().
+      registration_journal_entry_id: string | null
+      payment_journal_entry_id: string | null
+      paid_at: string | null
       is_credit_note: boolean
       credited_invoice_id: string | null
       supplier_invoice_number: string
@@ -338,9 +350,10 @@ export const POST = withApiV1<{ params: Promise<{ companyId: string; id: string
       }
     }
 
-    // Accrual: post the reversing JE. Cash basis: skip (no original
-    // registration entry to reverse; refund is recognized when the bank
-    // transaction is booked).
+    // Post the reversing JE whenever the original actually reached the ledger.
+    // Kontantmetoden skips only while the original is still UNPAID: a paid one
+    // was booked by its payment verifikat (expense + 2641 ingående moms), so
+    // skipping there would overstate both the cost and the moms deduction.
     const { data: settings } = await ctx.supabase
       .from('company_settings')
       .select('accounting_method')
@@ -350,7 +363,7 @@ export const POST = withApiV1<{ params: Promise<{ companyId: string; id: string
       ?? 'accrual') as AccountingMethod
 
     let journalEntryId: string | null = null
-    if (accountingMethod === 'accrual') {
+    if (supplierCreditNoteNeedsJournalEntry(accountingMethod, typed)) {
       try {
         const entry = await createSupplierCreditNoteEntry(
           ctx.supabase,

lib/bookkeeping/__tests__/booking-mode.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest'
-import { booksInvoicesOnIssue, cashPartialBlockReason } from '../booking-mode'
+import { booksInvoicesOnIssue, cashPartialBlockReason, supplierCreditNoteNeedsJournalEntry } from '../booking-mode'
 
 describe('booksInvoicesOnIssue (#967)', () => {
   it('books at issue for accrual companies by default', () => {
@@ -66,3 +66,69 @@ describe('cashPartialBlockReason', () => {
     expect(cashPartialBlockReason({ ...base, priorPaidAmount: undefined })).toBeNull()
   })
 })
+
+describe('supplierCreditNoteNeedsJournalEntry', () => {
+  const unpaid = {
+    registration_journal_entry_id: null,
+    payment_journal_entry_id: null,
+    status: 'registered',
+    paid_at: null,
+    paid_amount: 0,
+  }
+
+  it('always reverses under faktureringsmetoden, even for an unpaid original', () => {
+    expect(supplierCreditNoteNeedsJournalEntry('accrual', unpaid)).toBe(true)
+    // Empty/absent accounting_method falls back to accrual, matching the rest
+    // of the module.
+    expect(supplierCreditNoteNeedsJournalEntry('', unpaid)).toBe(true)
+  })
+
+  it('skips under kontantmetoden while the original is still unpaid', () => {
+    // Nothing reached the ledger: there is no entry to reverse and
+    // recognition correctly waits for the refund.
+    expect(supplierCreditNoteNeedsJournalEntry('cash', unpaid)).toBe(false)
+  })
+
+  it('reverses under kontantmetoden once the payment booked the expense', () => {
+    // The payment verifikat already booked expense + 2641 ingående moms;
+    // skipping the reversal would overstate both.
+    expect(
+      supplierCreditNoteNeedsJournalEntry('cash', {
+        ...unpaid,
+        status: 'paid',
+        paid_at: '2026-03-12',
+        paid_amount: 781,
+        payment_journal_entry_id: 'je-1',
+      }),
+    ).toBe(true)
+  })
+
+  it('reverses on any single booked-ness signal in isolation', () => {
+    // Each signal must stand alone: rows written by different payment paths
+    // set different subsets of these fields.
+    expect(supplierCreditNoteNeedsJournalEntry('cash', { ...unpaid, payment_journal_entry_id: 'je-1' })).toBe(true)
+    expect(supplierCreditNoteNeedsJournalEntry('cash', { ...unpaid, registration_journal_entry_id: 'je-2' })).toBe(true)
+    expect(supplierCreditNoteNeedsJournalEntry('cash', { ...unpaid, status: 'paid' })).toBe(true)
+    expect(supplierCreditNoteNeedsJournalEntry('cash', { ...unpaid, paid_at: '2026-03-12' })).toBe(true)
+  })
+
+  it('catches a part-paid original that predates the #1413 guard', () => {
+    // status is still 'partially_paid', but a payment entry exists, so the
+    // expense IS on the ledger. status alone would miss this.
+    expect(
+      supplierCreditNoteNeedsJournalEntry('cash', {
+        ...unpaid,
+        status: 'partially_paid',
+        paid_amount: 781,
+        payment_journal_entry_id: 'je-3',
+      }),
+    ).toBe(true)
+  })
+
+  it('ignores sub-öre noise and missing rows', () => {
+    expect(supplierCreditNoteNeedsJournalEntry('cash', { ...unpaid, paid_amount: 0.004 })).toBe(false)
+    expect(supplierCreditNoteNeedsJournalEntry('cash', { ...unpaid, paid_amount: null })).toBe(false)
+    expect(supplierCreditNoteNeedsJournalEntry('cash', null)).toBe(false)
+    expect(supplierCreditNoteNeedsJournalEntry('cash', undefined)).toBe(false)
+  })
+})

lib/bookkeeping/booking-mode.ts

@@ -55,3 +55,50 @@ export function cashPartialBlockReason(opts: {
   if (Math.round((opts.priorPaidAmount ?? 0) * 100) !== 0) return 'previously_partially_paid'
   return null
 }
+
+/** The booked-ness signals on a supplier invoice being credited. */
+export interface SupplierCreditNoteOriginal {
+  /** Set when the invoice was booked at registration (faktureringsmetoden). */
+  registration_journal_entry_id?: string | null
+  /** Set when the invoice was booked at payment (kontantmetoden). */
+  payment_journal_entry_id?: string | null
+  status?: string | null
+  paid_at?: string | null
+  paid_amount?: number | null
+}
+
+/**
+ * Whether a supplier credit note must post a reversing verifikat.
+ *
+ * The mirror of creditNoteNeedsJournalEntry() on the customer side: a credit
+ * note reverses whatever actually reached the ledger, so the test is "did the
+ * original get booked", not "which accounting method is configured".
+ *
+ * Under faktureringsmetoden the original was booked at registration, so the
+ * reversal always applies. Under kontantmetoden nothing is booked at
+ * registration, and skipping the credit note is correct while the invoice is
+ * still unpaid: there is no entry to reverse and recognition waits for cash.
+ * But once the invoice has been PAID, the payment verifikat has already booked
+ * the expense and claimed the ingående moms (2641, ruta 48). Leaving that
+ * un-reversed overstates both the cost and the VAT deduction for as long as
+ * the credit stands, and the invoice is marked 'credited' with no accounting
+ * trace at all, so nothing links a later refund back to it.
+ *
+ * createSupplierCreditNoteEntry's shape works for both cases: the 2440 debit
+ * leaves a claim on the supplier that the refund payment clears, exactly as
+ * the customer side leaves a 1510 credit for a refund owed to the customer.
+ */
+export function supplierCreditNoteNeedsJournalEntry(
+  accountingMethod: string,
+  original: SupplierCreditNoteOriginal | null | undefined,
+): boolean {
+  if ((accountingMethod || 'accrual') === 'accrual') return true
+  if (!original) return false
+  return (
+    !!original.registration_journal_entry_id ||
+    !!original.payment_journal_entry_id ||
+    original.status === 'paid' ||
+    !!original.paid_at ||
+    Math.round(Math.abs(original.paid_amount ?? 0) * 100) !== 0
+  )
+}

lib/pending-operations/commit.ts

@@ -35,7 +35,7 @@ import {
   createCreditNoteJournalEntry,
 } from '@/lib/bookkeeping/invoice-entries'
 import { resolveSettlementAccount } from '@/lib/bookkeeping/settlement-account'
-import { cashPartialBlockReason } from '@/lib/bookkeeping/booking-mode'
+import { cashPartialBlockReason, supplierCreditNoteNeedsJournalEntry } from '@/lib/bookkeeping/booking-mode'
 import { ensureManualCashAccount } from '@/lib/cash-accounts/service'
 import { createJournalEntry, findFiscalPeriod, getSwedishLocalDate, reverseEntry, validateBalance } from '@/lib/bookkeeping/engine'
 import {
@@ -3787,7 +3787,10 @@ async function commitCreditSupplierInvoice(
   const accountingMethod = settings?.accounting_method || 'accrual'
 
   let journalEntryId: string | null = null
-  if (accountingMethod === 'accrual') {
+  // Kontantmetoden skips only while the original is still UNPAID: a paid one
+  // was already booked by its payment verifikat (expense + 2641 ingående
+  // moms), and leaving that un-reversed overstates cost and moms deduction.
+  if (supplierCreditNoteNeedsJournalEntry(accountingMethod, original)) {
     try {
       const je = await createSupplierCreditNoteEntry(
         supabase,