fix(errors): translate typed engine errors instead of leaking raw messages as journal_entry_error (#1048)

Typed bookkeeping Error instances passed to getErrorMessage() matched the
bare-envelope branch (any object with string code + message) and returned
their raw English message verbatim, so the categorize and match-invoice
routes surfaced strings like DB check-constraint violations directly in the
user's toast (issue #337).

- get-error-message.ts: when the bare-envelope shape is an Error instance,
  normalize it into the structured envelope ({ error: { code, message,
  account_numbers, details } }) so the existing per-code Swedish branches
  own the translation; plain forwarded envelopes keep the passthrough.
- get-error-message.ts: structured-path final fallback now prefers the
  registry's message_sv for known codes whose message is not Swedish, so
  typed codes without a dynamic branch (e.g. CANNOT_REVERSE_STORNO) cannot
  surface English either.
- categorize + match-invoice routes: always map the caught error through
  getErrorMessage (the raw error is already logged); untyped errors fall to
  the Swedish context fallback instead of leaking err.message.
- Tests: new instance-translation suite in lib/errors, typed-error case in
  the categorize route suite, and deliberate updates of the two tests that
  pinned raw 'Period locked' passthrough.

Fixes #337

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

app/api/transactions/[id]/categorize/__tests__/route.test.ts

@@ -7,6 +7,7 @@ import {
   makeTransaction,
 } from '@/tests/helpers'
 import { eventBus } from '@/lib/events'
+import { JournalEntryNotBalancedError } from '@/lib/bookkeeping/errors'
 
 const { supabase: mockSupabase, enqueue, reset } = createQueuedMockSupabase()
 vi.mock('@/lib/supabase/server', () => ({
@@ -325,7 +326,47 @@ describe('POST /api/transactions/[id]/categorize', () => {
     expect(status).toBe(200)
     expect(body.success).toBe(true)
     expect(body.journal_entry_created).toBe(false)
-    expect(body.journal_entry_error).toBe('Period locked')
+    // Untyped errors no longer leak their raw English message (issue #337):
+    // they map to the Swedish transaction-context fallback.
+    expect(body.journal_entry_error).toBe('Kunde inte hantera transaktionen. Försök igen.')
+  })
+
+  it('translates typed engine errors to Swedish in journal_entry_error (issue #337)', async () => {
+    const tx = makeTransaction({
+      id: 'tx-1',
+      amount: -500,
+      merchant_name: 'Test',
+      journal_entry_id: null,
+    })
+
+    enqueue({ data: tx, error: null })
+    enqueue({ data: { entity_type: 'enskild_firma', fiscal_year_start_month: 1 }, error: null })
+    enqueue({ data: [{ id: 'period-1' }], error: null })
+
+    mockCreateTransactionJournalEntry.mockRejectedValue(new JournalEntryNotBalancedError(100, 80))
+
+    // Update transaction
+    enqueue({ data: null, error: null })
+
+    const request = createMockRequest('/api/transactions/tx-1/categorize', {
+      method: 'POST',
+      body: { is_business: true, category: 'expense_software' },
+    })
+    const response = await POST(request, createMockRouteParams({ id: 'tx-1' }))
+    const { status, body } = await parseJsonResponse<{
+      success: boolean
+      journal_entry_created: boolean
+      journal_entry_error: string
+    }>(response)
+
+    expect(status).toBe(200)
+    expect(body.success).toBe(true)
+    expect(body.journal_entry_created).toBe(false)
+    expect(body.journal_entry_error).toContain('balanserar inte')
+    expect(body.journal_entry_error).toMatch(/100/)
+    expect(body.journal_entry_error).toMatch(/80/)
+    expect(body.journal_entry_error).not.toContain('not balanced')
+    expect(body.journal_entry_error).not.toContain('check constraint')
   })
 
   it('returns 500 when transaction update fails', async () => {

app/api/transactions/[id]/categorize/route.ts

@@ -18,7 +18,7 @@ import {
   escapeLikePattern,
   normalizeOcrReference,
 } from '@/lib/invoices/duplicate-payment-guard'
-import { AccountsNotInChartError, accountsNotInChartResponse, isBookkeepingError } from '@/lib/bookkeeping/errors'
+import { AccountsNotInChartError, accountsNotInChartResponse } from '@/lib/bookkeeping/errors'
 import { collectMappingResultAccounts, findUnresolvableAccounts } from '@/lib/bookkeeping/account-validation'
 import { getErrorMessage } from '@/lib/errors/get-error-message'
 import type { Logger } from '@/lib/logger'
@@ -640,14 +640,11 @@ export const POST = withRouteContext(
       if (err instanceof AccountsNotInChartError) {
         return accountsNotInChartResponse(err)
       }
-      // Bookkeeping errors map to Swedish via the registry. Other errors get
-      // their raw message: the categorization is preserved either way so the
-      // user can still re-book the verifikation manually.
-      if (isBookkeepingError(err)) {
-        journalEntryError = getErrorMessage(err, { context: 'transaction' })
-      } else {
-        journalEntryError = err instanceof Error ? err.message : 'Unknown error'
-      }
+      // All errors map to Swedish via getErrorMessage: the raw message is
+      // already logged above and must never reach the user verbatim (issue
+      // #337). The categorization is preserved either way so the user can
+      // still re-book the verifikation manually.
+      journalEntryError = getErrorMessage(err, { context: 'transaction' })
     }
 
     // direction_mismatch = a mirrored refund/repayment booking; learning it

app/api/transactions/[id]/match-invoice/__tests__/route.test.ts

@@ -1048,7 +1048,9 @@ describe('POST /api/transactions/[id]/match-invoice', () => {
     expect(status).toBe(200)
     expect(body.success).toBe(true)
     expect(body.journal_entry_id).toBeNull()
-    expect(body.journal_entry_error).toBe('Period locked')
+    // Untyped errors no longer leak their raw English message (issue #337):
+    // they map to the Swedish invoice-context fallback.
+    expect(body.journal_entry_error).toBe('Kunde inte hantera fakturan. Försök igen.')
   })
 
   // ────────────────────────────────────────────────────────────────

app/api/transactions/[id]/match-invoice/route.ts

@@ -4,7 +4,7 @@ import { buildInvoicePaymentClearingLines } from '@/lib/bookkeeping/invoice-paym
 import { resolveSettlementAccount } from '@/lib/bookkeeping/settlement-account'
 import { fetchExchangeRate } from '@/lib/currency/riksbanken'
 import { reverseEntry, createJournalEntry, findFiscalPeriod } from '@/lib/bookkeeping/engine'
-import { AccountsNotInChartError, isBookkeepingError } from '@/lib/bookkeeping/errors'
+import { AccountsNotInChartError } from '@/lib/bookkeeping/errors'
 import { getErrorMessage } from '@/lib/errors/get-error-message'
 import { withRouteContext } from '@/lib/api/with-route-context'
 import { errorResponse, errorResponseFromCode } from '@/lib/errors/get-structured-error'
@@ -480,12 +480,9 @@ export const POST = withRouteContext(
       }
       txLog.error('failed to create payment journal entry', err as Error)
       // Other errors are recorded but don't abort the match: the user can
-      // re-book the verifikation manually.
-      if (isBookkeepingError(err)) {
-        journalEntryError = getErrorMessage(err, { context: 'invoice' })
-      } else {
-        journalEntryError = err instanceof Error ? err.message : 'Unknown error'
-      }
+      // re-book the verifikation manually. All errors map to Swedish via
+      // getErrorMessage; the raw message must never reach the user (issue #337).
+      journalEntryError = getErrorMessage(err, { context: 'invoice' })
     }
 
     // Underlag for the payment verifikation: re-attach the invoice PDF that