Supp/verifikationer inconsitency (#369)

* feat(bookkeeping): implement reset bookkeeping functionality with safeguards

* feat(migrations): restore relaxed trigger for retroactive first fiscal year

lib/errors/get-error-message.ts

@@ -88,6 +88,30 @@ const ERROR_PATTERN_MAP: [RegExp, string | null][] = [
     /Entry date .+ is outside fiscal period/i,
     'Datumet ligger utanför det valda räkenskapsåret.',
   ],
+  [
+    /Only company owners and admins can delete vouchers/i,
+    'Endast ägare och administratörer kan radera verifikationer.',
+  ],
+  [
+    /Journal entry not found/i,
+    'Verifikationen kunde inte hittas.',
+  ],
+  [
+    /Only posted entries can be deleted/i,
+    'Endast bokförda verifikationer kan raderas.',
+  ],
+  [
+    /Cannot delete voucher in a closed fiscal period/i,
+    'Verifikationen kan inte raderas — räkenskapsåret är stängt.',
+  ],
+  [
+    /Cannot delete voucher in a locked fiscal period/i,
+    'Verifikationen kan inte raderas — perioden är låst.',
+  ],
+  [
+    /Cannot delete: other entries reference this voucher/i,
+    'Verifikationen kan inte raderas eftersom andra verifikationer (t.ex. storno eller rättelse) refererar till den.',
+  ],
   [
     /timed out after \d+m?s/i,
     'Anslutningen mot tjänsten tog för lång tid. Försök igen.',

lib/import/__tests__/fiscal-period-start-day.pg.test.ts

@@ -0,0 +1,64 @@
+import { describe, expect, it } from 'vitest'
+import { getPool } from '@/tests/pg/setup'
+import { seedCompany } from '@/tests/pg/fixtures'
+
+// Covers enforce_first_of_month_for_subsequent_periods (migration
+// 20260418120000). The trigger only blocks mid-month period_start when a
+// strictly earlier period exists — so importing a company's chronologically
+// first fiscal year (förlängt första räkenskapsår) via SIE must succeed even
+// after a later period was created during onboarding.
+describe('fiscal_periods: subsequent-period start-day trigger', () => {
+  async function insertPeriod(
+    companyId: string,
+    name: string,
+    periodStart: string,
+    periodEnd: string,
+  ) {
+    return getPool().query(
+      `INSERT INTO public.fiscal_periods
+         (company_id, name, period_start, period_end, is_closed, opening_balances_set)
+       VALUES ($1, $2, $3, $4, false, false)
+       RETURNING id`,
+      [companyId, name, periodStart, periodEnd],
+    )
+  }
+
+  it('allows a mid-month start when no earlier period exists', async () => {
+    const { companyId } = await seedCompany()
+
+    const { rows } = await insertPeriod(
+      companyId,
+      'Räkenskapsår 2025',
+      '2025-06-15',
+      '2026-06-30',
+    )
+    expect(rows[0]!.id).toBeTruthy()
+  })
+
+  it('allows importing an earlier mid-month period after a later day-1 period exists', async () => {
+    const { companyId } = await seedCompany()
+
+    // Onboarding-created period (day 1, year N).
+    await insertPeriod(companyId, 'Räkenskapsår 2025', '2025-01-01', '2025-12-31')
+
+    // SIE import of förlängt första räkenskapsår — earlier in time,
+    // mid-month start. This used to fail with the old trigger.
+    const { rows } = await insertPeriod(
+      companyId,
+      'Räkenskapsår 2023/2024',
+      '2023-06-15',
+      '2024-12-31',
+    )
+    expect(rows[0]!.id).toBeTruthy()
+  })
+
+  it('still rejects mid-month start when a strictly earlier period already exists', async () => {
+    const { companyId } = await seedCompany()
+
+    await insertPeriod(companyId, 'Räkenskapsår 2024', '2024-01-01', '2024-12-31')
+
+    await expect(
+      insertPeriod(companyId, 'Räkenskapsår 2025 (bad)', '2025-06-15', '2026-06-30'),
+    ).rejects.toThrow(/Non-first fiscal period must start on the 1st of a month/)
+  })
+})