diff --git a/extensions/general/mcp-server/__tests__/voucher-tools.test.ts b/extensions/general/mcp-server/__tests__/voucher-tools.test.ts
new file mode 100644
index 00000000..6e517e86
--- /dev/null
+++ b/extensions/general/mcp-server/__tests__/voucher-tools.test.ts
@@ -0,0 +1,279 @@
+/**
+ * Staging-time gate tests for gnubok_create_voucher.
+ *
+ * The executor-level gates (period lock, balance, status === 'posted' for
+ * correct_entry) are tested in lib/pending-operations/__tests__/. This file
+ * covers the pre-staging gates added to the MCP tool layer for UX — explicit
+ * fiscal_period_id validation, inactive/missing account rejection, and the
+ * source_type-not-staged invariant.
+ */
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { createQueuedMockSupabase } from '@/tests/helpers'
+
+vi.mock('@/lib/bookkeeping/engine', async () => {
+  const actual = await vi.importActual<typeof import('@/lib/bookkeeping/engine')>(
+    '@/lib/bookkeeping/engine'
+  )
+  return {
+    ...actual,
+    findFiscalPeriod: vi.fn(),
+  }
+})
+
+import { tools } from '../server'
+import { findFiscalPeriod } from '@/lib/bookkeeping/engine'
+
+const createVoucher = tools.find((t) => t.name === 'gnubok_create_voucher')!
+const correctEntry = tools.find((t) => t.name === 'gnubok_correct_entry')!
+
+beforeEach(() => {
+  vi.clearAllMocks()
+})
+
+const balancedLines = [
+  { account_number: '1010', debit_amount: 250, credit_amount: 0 },
+  { account_number: '1930', debit_amount: 0, credit_amount: 250 },
+]
+
+describe('gnubok_create_voucher — staging gates', () => {
+  it('is registered and mapped to bookkeeping:write scope', async () => {
+    const { TOOL_SCOPE_MAP } = await import('@/lib/auth/api-keys')
+    expect(createVoucher).toBeDefined()
+    expect(createVoucher.annotations.readOnlyHint).toBe(false)
+    expect(TOOL_SCOPE_MAP.gnubok_create_voucher).toBe('bookkeeping:write')
+  })
+
+  it('rejects unbalanced lines before staging', async () => {
+    const { supabase } = createQueuedMockSupabase()
+    await expect(
+      createVoucher.execute(
+        {
+          entry_date: '2026-05-12',
+          description: 'unbalanced',
+          fiscal_period_id: 'fp-1',
+          lines: [
+            { account_number: '1010', debit_amount: 100, credit_amount: 0 },
+            { account_number: '1930', debit_amount: 0, credit_amount: 80 },
+          ],
+        },
+        'company-1',
+        'user-1',
+        supabase as never,
+      ),
+    ).rejects.toThrow(/not balanced/i)
+  })
+
+  it('rejects when an explicit fiscal_period_id is closed', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    // fiscal_periods fetch returns a closed period
+    enqueue({
+      data: {
+        id: 'fp-closed',
+        is_closed: true,
+        period_start: '2026-01-01',
+        period_end: '2026-03-31',
+        name: 'Q1 2026',
+      },
+      error: null,
+    })
+
+    await expect(
+      createVoucher.execute(
+        {
+          entry_date: '2026-02-15',
+          description: 'attempt to post in closed Q1',
+          fiscal_period_id: 'fp-closed',
+          lines: balancedLines,
+        },
+        'company-1',
+        'user-1',
+        supabase as never,
+      ),
+    ).rejects.toThrow(/låst/i)
+    // findFiscalPeriod must NOT be called when an explicit ID was supplied.
+    expect(findFiscalPeriod).not.toHaveBeenCalled()
+  })
+
+  it('rejects when an explicit fiscal_period_id does not exist', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: null, error: null }) // fiscal_periods fetch — not found
+
+    await expect(
+      createVoucher.execute(
+        {
+          entry_date: '2026-05-12',
+          description: 'unknown period uuid',
+          fiscal_period_id: 'fp-nonexistent',
+          lines: balancedLines,
+        },
+        'company-1',
+        'user-1',
+        supabase as never,
+      ),
+    ).rejects.toThrow(/not found/i)
+  })
+
+  it('rejects when entry_date is outside the supplied period', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({
+      data: {
+        id: 'fp-1',
+        is_closed: false,
+        period_start: '2026-01-01',
+        period_end: '2026-03-31',
+        name: 'Q1 2026',
+      },
+      error: null,
+    })
+
+    await expect(
+      createVoucher.execute(
+        {
+          entry_date: '2026-05-12',
+          description: 'date outside Q1',
+          fiscal_period_id: 'fp-1',
+          lines: balancedLines,
+        },
+        'company-1',
+        'user-1',
+        supabase as never,
+      ),
+    ).rejects.toThrow(/utanför/i)
+  })
+
+  it('rejects when a referenced account is missing from the chart', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({
+      data: {
+        id: 'fp-1',
+        is_closed: false,
+        period_start: '2026-01-01',
+        period_end: '2026-12-31',
+        name: '2026',
+      },
+      error: null,
+    })
+    // chart_of_accounts returns nothing — both accounts unknown
+    enqueue({ data: [], error: null })
+
+    await expect(
+      createVoucher.execute(
+        {
+          entry_date: '2026-05-12',
+          description: 'unknown accounts',
+          fiscal_period_id: 'fp-1',
+          lines: balancedLines,
+        },
+        'company-1',
+        'user-1',
+        supabase as never,
+      ),
+    ).rejects.toThrow(/saknas i kontoplanen/i)
+  })
+
+  it('rejects when a referenced account exists but is inactive', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({
+      data: {
+        id: 'fp-1',
+        is_closed: false,
+        period_start: '2026-01-01',
+        period_end: '2026-12-31',
+        name: '2026',
+      },
+      error: null,
+    })
+    enqueue({
+      data: [
+        { account_number: '1010', account_name: 'Balanserade utgifter', is_active: false },
+        { account_number: '1930', account_name: 'Företagskonto', is_active: true },
+      ],
+      error: null,
+    })
+
+    await expect(
+      createVoucher.execute(
+        {
+          entry_date: '2026-05-12',
+          description: 'inactive account',
+          fiscal_period_id: 'fp-1',
+          lines: balancedLines,
+        },
+        'company-1',
+        'user-1',
+        supabase as never,
+      ),
+    ).rejects.toThrow(/inaktiv/i)
+  })
+
+  it('happy path: stages with no source_type in params (executor hardcodes it)', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({
+      data: {
+        id: 'fp-1',
+        is_closed: false,
+        period_start: '2026-01-01',
+        period_end: '2026-12-31',
+        name: '2026',
+      },
+      error: null,
+    })
+    enqueue({
+      data: [
+        { account_number: '1010', account_name: 'Balanserade utgifter', is_active: true },
+        { account_number: '1930', account_name: 'Företagskonto', is_active: true },
+      ],
+      error: null,
+    })
+    enqueue({ data: { id: 'op-staged' }, error: null }) // pending_operations insert
+
+    const result = (await createVoucher.execute(
+      {
+        entry_date: '2026-05-12',
+        description: 'Capitalize Cursor',
+        fiscal_period_id: 'fp-1',
+        lines: balancedLines,
+      },
+      'company-1',
+      'user-1',
+      supabase as never,
+    )) as { staged: boolean; operation_id?: string; preview: Record<string, unknown> }
+
+    expect(result.staged).toBe(true)
+    expect(result.operation_id).toBe('op-staged')
+    expect(result.preview.total_debit).toBe(250)
+    expect(result.preview.total_credit).toBe(250)
+
+    // Critical: the staged pending_operations row must NOT carry source_type.
+    // The executor always hardcodes 'manual'. Look at the insert call.
+    const insertCalls = (supabase.from as ReturnType<typeof vi.fn>).mock.calls
+    expect(insertCalls.some((args) => args[0] === 'pending_operations')).toBe(true)
+  })
+})
+
+describe('gnubok_correct_entry — registration', () => {
+  it('is registered with bookkeeping:write scope and is not read-only', async () => {
+    const { TOOL_SCOPE_MAP } = await import('@/lib/auth/api-keys')
+    expect(correctEntry).toBeDefined()
+    expect(correctEntry.annotations.readOnlyHint).toBe(false)
+    expect(TOOL_SCOPE_MAP.gnubok_correct_entry).toBe('bookkeeping:write')
+  })
+
+  it('rejects unbalanced replacement lines before staging', async () => {
+    const { supabase } = createQueuedMockSupabase()
+    await expect(
+      correctEntry.execute(
+        {
+          entry_id: 'je-1',
+          lines: [
+            { account_number: '2645', debit_amount: 250, credit_amount: 0 },
+            { account_number: '2614', debit_amount: 0, credit_amount: 200 },
+          ],
+        },
+        'company-1',
+        'user-1',
+        supabase as never,
+      ),
+    ).rejects.toThrow(/not balanced/i)
+  })
+})
diff --git a/extensions/general/mcp-server/server.ts b/extensions/general/mcp-server/server.ts
index 015ebe28..484f9473 100644
--- a/extensions/general/mcp-server/server.ts
+++ b/extensions/general/mcp-server/server.ts
@@ -42,7 +42,7 @@ import { generateSupplierLedger } from '@/lib/reports/supplier-ledger'
 import { getReconciliationStatus } from '@/lib/reconciliation/bank-reconciliation'
 import { createInvoicePaymentJournalEntry, createInvoiceCashEntry, createInvoiceJournalEntry } from '@/lib/bookkeeping/invoice-entries'
 import { findMatchingInvoices } from '@/lib/invoices/invoice-matching'
-import { reverseEntry } from '@/lib/bookkeeping/engine'
+import { findFiscalPeriod, reverseEntry, validateBalance } from '@/lib/bookkeeping/engine'
 import { closePeriod, lockPeriod } from '@/lib/core/bookkeeping/period-service'
 import { validateYearEndReadiness, previewYearEndClosing } from '@/lib/core/bookkeeping/year-end-service'
 import { generateSIEExport } from '@/lib/reports/sie-export'
@@ -5367,6 +5367,334 @@ export const tools: McpTool[] = [
       )
     },
   },
+
+  // ── Phase 4: arbitrary-line bookkeeping primitives ───────────────
+
+  {
+    name: 'gnubok_create_voucher',
+    description: 'Stage a manual verifikation with arbitrary balanced lines. Use for capitalization (e.g. 1010), period-end accruals, FX adjustments, and rättelseposter outside categorize_transaction. HIGH risk — always staged, never auto-committed.',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        entry_date: { type: 'string', description: 'Voucher date (YYYY-MM-DD)' },
+        description: { type: 'string', description: 'Verifikationstext (required, min 1 char)' },
+        fiscal_period_id: { type: 'string', description: 'UUID of fiscal period. If omitted, resolved from entry_date.' },
+        voucher_series: { type: 'string', description: 'Single letter A–Z. Defaults to A.' },
+        notes: { type: 'string', description: 'Internal notes (max 2000 chars) — visible on the verifikation but not on reports.' },
+        lines: {
+          type: 'array',
+          description: 'At least 2 balanced lines. sum(debit_amount) === sum(credit_amount), both > 0.',
+          items: {
+            type: 'object',
+            properties: {
+              account_number: { type: 'string', description: '4-digit BAS account number, e.g. "1010"' },
+              debit_amount: { type: 'number', description: 'Debit amount in SEK (≥ 0)' },
+              credit_amount: { type: 'number', description: 'Credit amount in SEK (≥ 0)' },
+              line_description: { type: 'string' },
+              currency: { type: 'string', description: 'ISO 4217, defaults to SEK' },
+              amount_in_currency: { type: 'number', description: 'Original amount if currency is not SEK' },
+              exchange_rate: { type: 'number' },
+              tax_code: { type: 'string', description: 'Free-text tag — does NOT drive momsdeklaration ruta mapping. The BAS account number is what determines which ruta the line lands in (e.g. 2641 → ruta 48, 2614 → ruta 30). Pick the correct account first.' },
+              cost_center: { type: 'string' },
+              project: { type: 'string' },
+            },
+            required: ['account_number'],
+          },
+        },
+      },
+      required: ['entry_date', 'description', 'lines'],
+    },
+    outputSchema: STAGED_OPERATION_SCHEMA,
+    annotations: { readOnlyHint: false, destructiveHint: false, idempotentHint: false, openWorldHint: false },
+    async execute(args, companyId, userId, supabase, actor) {
+      const entryDate = args.entry_date as string
+      const description = args.description as string
+      const rawLines = args.lines as Array<Record<string, unknown>> | undefined
+
+      if (!entryDate || !description || !Array.isArray(rawLines) || rawLines.length < 2) {
+        throw new Error('entry_date, description, and at least two lines are required')
+      }
+
+      // Normalize so validateBalance + preview see consistent numeric types.
+      const lines = rawLines.map((l) => ({
+        account_number: String(l.account_number ?? ''),
+        debit_amount: Number(l.debit_amount) || 0,
+        credit_amount: Number(l.credit_amount) || 0,
+        line_description: l.line_description ? String(l.line_description) : undefined,
+        currency: l.currency ? String(l.currency) : undefined,
+        amount_in_currency: l.amount_in_currency !== undefined ? Number(l.amount_in_currency) : undefined,
+        exchange_rate: l.exchange_rate !== undefined ? Number(l.exchange_rate) : undefined,
+        tax_code: l.tax_code ? String(l.tax_code) : undefined,
+        cost_center: l.cost_center ? String(l.cost_center) : undefined,
+        project: l.project ? String(l.project) : undefined,
+      }))
+
+      // Pre-flight: catch unbalanced lines before staging so the agent gets a
+      // tight feedback loop instead of a rejected pending_operation later.
+      const balance = validateBalance(lines)
+      if (!balance.valid) {
+        throw new Error(
+          `Lines are not balanced: debits ${balance.totalDebit} SEK, credits ${balance.totalCredit} SEK. ` +
+          'Both must be positive and equal.'
+        )
+      }
+
+      // Resolve fiscal period. Two paths:
+      //   1. Caller supplied fiscal_period_id → verify it exists and is open.
+      //   2. Omitted → look up the open period covering entry_date.
+      // Both paths converge on a Swedish-language error if no valid open
+      // period is available. (NOTE: the executor re-checks period_lock at
+      // commit time — this staging gate is advisory and exists for UX, the
+      // commit-time guard is the authoritative one. Don't remove it as
+      // "redundant".)
+      let fiscalPeriodId = (args.fiscal_period_id as string | undefined) ?? null
+      if (fiscalPeriodId) {
+        const { data: period, error: periodErr } = await supabase
+          .from('fiscal_periods')
+          .select('id, is_closed, period_start, period_end, name')
+          .eq('id', fiscalPeriodId)
+          .eq('company_id', companyId)
+          .maybeSingle()
+        if (periodErr || !period) {
+          throw new Error(`Fiscal period ${fiscalPeriodId} not found for this company.`)
+        }
+        if (period.is_closed) {
+          throw new Error(
+            `Räkenskapsperioden "${period.name ?? fiscalPeriodId}" är låst. ` +
+            'Lås upp perioden, eller välj en öppen period.'
+          )
+        }
+        // Defense in depth: also verify the supplied period actually covers
+        // entry_date so the engine's EntryDateOutsideFiscalPeriodError surfaces
+        // as a Swedish message rather than a generic engine error.
+        if (entryDate < period.period_start || entryDate > period.period_end) {
+          throw new Error(
+            `Datumet ${entryDate} ligger utanför "${period.name ?? 'perioden'}" (${period.period_start}–${period.period_end}).`
+          )
+        }
+      } else {
+        fiscalPeriodId = await findFiscalPeriod(supabase, companyId, entryDate)
+      }
+      if (!fiscalPeriodId) {
+        throw new Error(`No open fiscal period covers ${entryDate}. Open a period or pick a different date.`)
+      }
+
+      // Resolve account names for the preview so the approver reads
+      // "1010 Balanserade utgifter / 2440 Leverantörsskulder" rather than
+      // bare numbers. Also gate: refuse to stage when any line references an
+      // unknown or inactive account so the approver isn't shown a voucher
+      // that would fail at commit time anyway.
+      const accountNumbers = [...new Set(lines.map((l) => l.account_number))]
+      const { data: accounts } = await supabase
+        .from('chart_of_accounts')
+        .select('account_number, account_name, is_active')
+        .eq('company_id', companyId)
+        .in('account_number', accountNumbers)
+      const accountInfo = new Map<string, { name: string; active: boolean }>()
+      for (const a of accounts || []) {
+        accountInfo.set(a.account_number as string, {
+          name: (a.account_name as string) ?? '',
+          active: Boolean(a.is_active),
+        })
+      }
+      const unknownAccounts = accountNumbers.filter((n) => !accountInfo.has(n))
+      const inactiveAccounts = accountNumbers.filter(
+        (n) => accountInfo.has(n) && !accountInfo.get(n)!.active,
+      )
+      if (unknownAccounts.length > 0 || inactiveAccounts.length > 0) {
+        const parts: string[] = []
+        if (unknownAccounts.length > 0) {
+          parts.push(`saknas i kontoplanen: ${unknownAccounts.join(', ')}`)
+        }
+        if (inactiveAccounts.length > 0) {
+          parts.push(`inaktiva: ${inactiveAccounts.join(', ')}`)
+        }
+        throw new Error(
+          `Kan inte skapa verifikation. Konton ${parts.join('; ')}. ` +
+          'Aktivera dem i kontoplanen eller välj andra konton.'
+        )
+      }
+
+      const previewLines = lines.map((l) => ({
+        account_number: l.account_number,
+        account_name: accountInfo.get(l.account_number)?.name ?? null,
+        debit_amount: l.debit_amount,
+        credit_amount: l.credit_amount,
+        line_description: l.line_description ?? null,
+      }))
+
+      // NOTE: source_type is intentionally NOT included in the staged params.
+      // The executor hardcodes 'manual' so a tampered or future direct-staged
+      // pending_operations row can't misrepresent the entry's origin.
+      return stagePendingOperation(supabase, companyId, userId, 'create_voucher',
+        `Manuell verifikation: ${description}`,
+        {
+          entry_date: entryDate,
+          description,
+          fiscal_period_id: fiscalPeriodId,
+          voucher_series: (args.voucher_series as string) || undefined,
+          notes: (args.notes as string) || undefined,
+          lines,
+        },
+        {
+          entry_date: entryDate,
+          description,
+          fiscal_period_id: fiscalPeriodId,
+          voucher_series: (args.voucher_series as string) || 'A',
+          total_debit: balance.totalDebit,
+          total_credit: balance.totalCredit,
+          line_count: lines.length,
+          lines: previewLines,
+          will: 'create a posted journal entry with a fresh sequential voucher number',
+        },
+        actor
+      )
+    },
+  },
+
+  {
+    name: 'gnubok_correct_entry',
+    description: 'Stage a rättelse for a posted verifikation per BFL 5 kap 5§ — storno + new corrected entry in the original period (never in-place edit). Use for partial fixes like 2641 → 2614/2645 while preserving the expense leg. Account drives momsdeklaration ruta, not tax_code. HIGH risk.',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        entry_id: { type: 'string', description: 'UUID of the posted journal entry to correct' },
+        lines: {
+          type: 'array',
+          description: 'Replacement lines (≥ 2, balanced). Use the same accounts as the original where unchanged.',
+          items: {
+            type: 'object',
+            properties: {
+              account_number: { type: 'string' },
+              debit_amount: { type: 'number' },
+              credit_amount: { type: 'number' },
+              line_description: { type: 'string' },
+              currency: { type: 'string' },
+              amount_in_currency: { type: 'number' },
+              exchange_rate: { type: 'number' },
+              tax_code: { type: 'string', description: 'Free-text tag — does NOT drive momsdeklaration ruta. Pick the correct BAS account first.' },
+              cost_center: { type: 'string' },
+              project: { type: 'string' },
+            },
+            required: ['account_number'],
+          },
+        },
+      },
+      required: ['entry_id', 'lines'],
+    },
+    outputSchema: STAGED_OPERATION_SCHEMA,
+    annotations: { readOnlyHint: false, destructiveHint: false, idempotentHint: false, openWorldHint: false },
+    async execute(args, companyId, userId, supabase, actor) {
+      const entryId = args.entry_id as string
+      const rawLines = args.lines as Array<Record<string, unknown>> | undefined
+
+      if (!entryId || !Array.isArray(rawLines) || rawLines.length < 2) {
+        throw new Error('entry_id and at least two lines are required')
+      }
+
+      const lines = rawLines.map((l) => ({
+        account_number: String(l.account_number ?? ''),
+        debit_amount: Number(l.debit_amount) || 0,
+        credit_amount: Number(l.credit_amount) || 0,
+        line_description: l.line_description ? String(l.line_description) : undefined,
+        currency: l.currency ? String(l.currency) : undefined,
+        amount_in_currency: l.amount_in_currency !== undefined ? Number(l.amount_in_currency) : undefined,
+        exchange_rate: l.exchange_rate !== undefined ? Number(l.exchange_rate) : undefined,
+        tax_code: l.tax_code ? String(l.tax_code) : undefined,
+        cost_center: l.cost_center ? String(l.cost_center) : undefined,
+        project: l.project ? String(l.project) : undefined,
+      }))
+
+      const balance = validateBalance(lines)
+      if (!balance.valid) {
+        throw new Error(
+          `Correction lines not balanced: debits ${balance.totalDebit}, credits ${balance.totalCredit}. ` +
+          'Both must be positive and equal.'
+        )
+      }
+
+      // Pre-flight: the executor checks again, but failing fast here gives the
+      // agent a clearer error message than waiting until commit-time.
+      // The Supabase types don't infer through `fiscal_periods!inner(...)`,
+      // so we type the row shape manually rather than fight the generics.
+      type OriginalRow = {
+        id: string
+        status: string
+        entry_date: string
+        description: string
+        voucher_number: number
+        voucher_series: string
+        fiscal_period_id: string
+        fiscal_periods: { name?: string; is_closed?: boolean } | { name?: string; is_closed?: boolean }[] | null
+        lines: Array<{
+          account_number: string
+          debit_amount: number | string
+          credit_amount: number | string
+          line_description: string | null
+        }> | null
+      }
+      const { data, error: origErr } = await supabase
+        .from('journal_entries')
+        .select(
+          'id, status, entry_date, description, voucher_number, voucher_series, fiscal_period_id, ' +
+          'fiscal_periods!inner(name, is_closed), lines:journal_entry_lines(account_number, debit_amount, credit_amount, line_description)'
+        )
+        .eq('id', entryId)
+        .eq('company_id', companyId)
+        .maybeSingle()
+      const original = data as OriginalRow | null
+
+      if (origErr || !original) throw new Error('Journal entry not found')
+      if (original.status !== 'posted') {
+        throw new Error(`Only posted entries can be corrected. Current status: ${original.status}.`)
+      }
+      const periodInfo = Array.isArray(original.fiscal_periods)
+        ? original.fiscal_periods[0]
+        : original.fiscal_periods
+      if (periodInfo?.is_closed) {
+        throw new Error(
+          `Fiscal period "${periodInfo.name ?? 'okänd'}" is closed. Unlock the period, or use omprövning for already-filed VAT.`
+        )
+      }
+
+      const originalLines = original.lines || []
+
+      return stagePendingOperation(supabase, companyId, userId, 'correct_entry',
+        `Rättelse: V${original.voucher_series}${original.voucher_number} — ${original.description}`,
+        {
+          entry_id: entryId,
+          lines,
+        },
+        {
+          original: {
+            entry_id: entryId,
+            voucher: `${original.voucher_series}${original.voucher_number}`,
+            entry_date: original.entry_date,
+            description: original.description,
+            lines: originalLines.map((l) => ({
+              account_number: l.account_number,
+              debit_amount: Number(l.debit_amount),
+              credit_amount: Number(l.credit_amount),
+              line_description: l.line_description,
+            })),
+          },
+          correction: {
+            total_debit: balance.totalDebit,
+            total_credit: balance.totalCredit,
+            line_count: lines.length,
+            lines: lines.map((l) => ({
+              account_number: l.account_number,
+              debit_amount: l.debit_amount,
+              credit_amount: l.credit_amount,
+              line_description: l.line_description ?? null,
+            })),
+          },
+          will: 'post a storno that mirrors the original, then post a new corrected entry, then mark the original as reversed (BFL 5 kap 5§)',
+        },
+        actor
+      )
+    },
+  },
 ]
 
 // ── MCP Protocol Handler ─────────────────────────────────────
diff --git a/lib/auth/api-keys.ts b/lib/auth/api-keys.ts
index c3185643..be22e401 100644
--- a/lib/auth/api-keys.ts
+++ b/lib/auth/api-keys.ts
@@ -121,6 +121,9 @@ export const TOOL_SCOPE_MAP: Record<string, ApiKeyScope> = {
   // Invoice conversion + crediting
   gnubok_convert_invoice:                 'invoices:write',
   gnubok_credit_invoice:                  'invoices:write',
+  // Phase 4: arbitrary-line bookkeeping primitives (high-risk, always staged)
+  gnubok_create_voucher:                  'bookkeeping:write',
+  gnubok_correct_entry:                   'bookkeeping:write',
 }
 
 export function validateScopes(scopes: unknown): ApiKeyScope[] | null {
diff --git a/lib/pending-operations/__tests__/actor-and-risk.pg.test.ts b/lib/pending-operations/__tests__/actor-and-risk.pg.test.ts
index b0f6274f..7c663d1f 100644
--- a/lib/pending-operations/__tests__/actor-and-risk.pg.test.ts
+++ b/lib/pending-operations/__tests__/actor-and-risk.pg.test.ts
@@ -66,6 +66,8 @@ describe('pending_operations: actor model + risk columns', () => {
       'run_currency_revaluation', 'explain_voucher_gap', 'uncategorize_transaction',
       'approve_supplier_invoice', 'credit_supplier_invoice',
       'credit_invoice', 'convert_invoice', 'import_sie',
+      // Phase 4: arbitrary-line bookkeeping primitives
+      'create_voucher', 'correct_entry',
     ]
 
     for (const op of expandedTypes) {
diff --git a/lib/pending-operations/__tests__/risk-tiers.test.ts b/lib/pending-operations/__tests__/risk-tiers.test.ts
index 0b3e1156..af588396 100644
--- a/lib/pending-operations/__tests__/risk-tiers.test.ts
+++ b/lib/pending-operations/__tests__/risk-tiers.test.ts
@@ -53,4 +53,14 @@ describe('risk-tiers', () => {
     expect(isHighRisk('create_customer')).toBe(false)
     expect(isHighRisk('categorize_transaction')).toBe(false)
   })
+
+  // Phase 4: arbitrary-line bookkeeping primitives. These accept any account
+  // and any amount from the caller, so they're HIGH despite being structurally
+  // similar to uncategorize_transaction (which is medium).
+  it('treats arbitrary-line voucher primitives as high risk', () => {
+    expect(getRiskLevel('create_voucher')).toBe('high')
+    expect(getRiskLevel('correct_entry')).toBe('high')
+    expect(isHighRisk('create_voucher')).toBe(true)
+    expect(isHighRisk('correct_entry')).toBe(true)
+  })
 })
diff --git a/lib/pending-operations/__tests__/voucher-executors.test.ts b/lib/pending-operations/__tests__/voucher-executors.test.ts
new file mode 100644
index 00000000..6f133059
--- /dev/null
+++ b/lib/pending-operations/__tests__/voucher-executors.test.ts
@@ -0,0 +1,425 @@
+/**
+ * Unit tests for commitCreateVoucher and commitCorrectEntry executors.
+ * The executors aren't exported individually, so we drive them through the
+ * public `commitPendingOperation` dispatcher.
+ */
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { eventBus } from '@/lib/events/bus'
+import { createQueuedMockSupabase, makeJournalEntry } from '@/tests/helpers'
+import type { PendingOperation } from '@/types'
+
+vi.mock('@/lib/bookkeeping/engine', async () => {
+  const actual = await vi.importActual<typeof import('@/lib/bookkeeping/engine')>(
+    '@/lib/bookkeeping/engine'
+  )
+  return {
+    ...actual,
+    createJournalEntry: vi.fn(),
+    findFiscalPeriod: vi.fn(),
+  }
+})
+
+vi.mock('@/lib/core/bookkeeping/storno-service', async () => {
+  const actual = await vi.importActual<typeof import('@/lib/core/bookkeeping/storno-service')>(
+    '@/lib/core/bookkeeping/storno-service'
+  )
+  return {
+    ...actual,
+    correctEntry: vi.fn(),
+  }
+})
+
+import { commitPendingOperation } from '../commit'
+import { createJournalEntry, findFiscalPeriod } from '@/lib/bookkeeping/engine'
+import { correctEntry } from '@/lib/core/bookkeeping/storno-service'
+
+function makePendingOp(overrides: Partial<PendingOperation>): PendingOperation {
+  return {
+    id: 'op-1',
+    user_id: 'user-1',
+    company_id: 'company-1',
+    operation_type: 'create_voucher',
+    status: 'pending',
+    title: 'test',
+    params: {},
+    preview_data: {},
+    result_data: null,
+    actor_type: 'user',
+    actor_id: null,
+    actor_label: null,
+    risk_level: 'high',
+    created_at: '2026-05-12T00:00:00Z',
+    resolved_at: null,
+    updated_at: '2026-05-12T00:00:00Z',
+    ...overrides,
+  } as PendingOperation
+}
+
+beforeEach(() => {
+  vi.clearAllMocks()
+  eventBus.clear()
+})
+
+// ─── create_voucher ─────────────────────────────────────────────────
+
+describe('commitPendingOperation: create_voucher', () => {
+  it('happy path: posts a balanced entry with the provided fiscal_period_id', async () => {
+    vi.mocked(createJournalEntry).mockResolvedValueOnce(
+      makeJournalEntry({ id: 'je-100', voucher_number: 42, voucher_series: 'A' })
+    )
+
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({ data: null, error: null }) // dispatcher's commit update
+
+    const op = makePendingOp({
+      params: {
+        entry_date: '2026-05-12',
+        description: 'Capitalize Cursor subscription to 1010',
+        fiscal_period_id: 'fp-1',
+        lines: [
+          { account_number: '1010', debit_amount: 250, credit_amount: 0 },
+          { account_number: '1930', debit_amount: 0, credit_amount: 250 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('committed')
+    expect(result.data).toMatchObject({
+      journal_entry_id: 'je-100',
+      voucher_number: 42,
+      voucher_series: 'A',
+      fiscal_period_id: 'fp-1',
+    })
+    expect(createJournalEntry).toHaveBeenCalledWith(
+      expect.anything(),
+      'company-1',
+      'user-1',
+      expect.objectContaining({
+        fiscal_period_id: 'fp-1',
+        entry_date: '2026-05-12',
+        description: 'Capitalize Cursor subscription to 1010',
+        source_type: 'manual',
+      }),
+      'mcp_create_voucher'
+    )
+    // findFiscalPeriod must NOT be called when fiscal_period_id is supplied —
+    // it's the caller's explicit choice.
+    expect(findFiscalPeriod).not.toHaveBeenCalled()
+  })
+
+  it('resolves fiscal_period from entry_date when omitted', async () => {
+    vi.mocked(findFiscalPeriod).mockResolvedValueOnce('fp-resolved')
+    vi.mocked(createJournalEntry).mockResolvedValueOnce(
+      makeJournalEntry({ id: 'je-101', voucher_number: 7 })
+    )
+
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({ data: null, error: null }) // dispatcher's commit update
+
+    const op = makePendingOp({
+      params: {
+        entry_date: '2026-05-12',
+        description: 'no fiscal_period_id',
+        lines: [
+          { account_number: '5410', debit_amount: 100, credit_amount: 0 },
+          { account_number: '1930', debit_amount: 0, credit_amount: 100 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('committed')
+    expect(result.data).toMatchObject({ fiscal_period_id: 'fp-resolved' })
+    expect(findFiscalPeriod).toHaveBeenCalledWith(expect.anything(), 'company-1', '2026-05-12')
+  })
+
+  it('returns 400 in Swedish when no fiscal period covers the date', async () => {
+    vi.mocked(findFiscalPeriod).mockResolvedValueOnce(null)
+
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({ data: null, error: null }) // dispatcher's reject update
+
+    const op = makePendingOp({
+      params: {
+        entry_date: '2027-12-31',
+        description: 'far-future date',
+        lines: [
+          { account_number: '5410', debit_amount: 100, credit_amount: 0 },
+          { account_number: '1930', debit_amount: 0, credit_amount: 100 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('failed')
+    expect(result.http_status).toBe(400)
+    expect(result.error).toMatch(/räkenskapsperiod/i)
+    expect(createJournalEntry).not.toHaveBeenCalled()
+  })
+
+  it('returns 400 when required fields are missing', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({ data: null, error: null }) // dispatcher's reject update
+
+    const op = makePendingOp({
+      params: {
+        entry_date: '2026-05-12',
+        // missing description and lines
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('failed')
+    expect(result.http_status).toBe(400)
+    expect(createJournalEntry).not.toHaveBeenCalled()
+  })
+
+  it('hardcodes source_type to manual even if params.source_type is tampered', async () => {
+    vi.mocked(createJournalEntry).mockResolvedValueOnce(
+      makeJournalEntry({ id: 'je-tamper', voucher_number: 8 })
+    )
+
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({ data: null, error: null }) // dispatcher's commit update
+
+    const op = makePendingOp({
+      params: {
+        entry_date: '2026-05-12',
+        description: 'attempt to spoof source_type',
+        fiscal_period_id: 'fp-1',
+        // Direct DB insert or future stager could put anything here.
+        source_type: 'bank_transaction',
+        lines: [
+          { account_number: '1010', debit_amount: 100, credit_amount: 0 },
+          { account_number: '1930', debit_amount: 0, credit_amount: 100 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('committed')
+    // Critical assertion: source_type is ALWAYS 'manual', never the
+    // caller-supplied value. Bypassing this lets a tampered operation
+    // misrepresent the audit trail as a bank-feed or invoice entry.
+    expect(createJournalEntry).toHaveBeenCalledWith(
+      expect.anything(),
+      'company-1',
+      'user-1',
+      expect.objectContaining({ source_type: 'manual' }),
+      'mcp_create_voucher'
+    )
+    expect(createJournalEntry).not.toHaveBeenCalledWith(
+      expect.anything(),
+      expect.anything(),
+      expect.anything(),
+      expect.objectContaining({ source_type: 'bank_transaction' }),
+      expect.anything()
+    )
+  })
+
+  it('returns 400 with Swedish error when params are unbalanced (tamper defense)', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({ data: null, error: null }) // dispatcher's reject update
+
+    const op = makePendingOp({
+      params: {
+        entry_date: '2026-05-12',
+        description: 'tampered: debit ≠ credit',
+        fiscal_period_id: 'fp-1',
+        // The MCP tool validates balance before staging, but a hand-inserted
+        // pending_operations row could bypass that. The executor's own
+        // validateBalance() gate catches it before reaching the engine.
+        lines: [
+          { account_number: '1010', debit_amount: 1000, credit_amount: 0 },
+          { account_number: '1930', debit_amount: 0, credit_amount: 800 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('failed')
+    expect(result.http_status).toBe(400)
+    expect(result.error).toMatch(/balanserar inte/i)
+    expect(createJournalEntry).not.toHaveBeenCalled()
+  })
+})
+
+// ─── correct_entry ──────────────────────────────────────────────────
+
+describe('commitPendingOperation: correct_entry', () => {
+  it('happy path: posts storno + corrected for a posted entry in an open period', async () => {
+    vi.mocked(correctEntry).mockResolvedValueOnce({
+      reversal: makeJournalEntry({ id: 'je-storno', voucher_number: 50 }),
+      corrected: makeJournalEntry({ id: 'je-corrected', voucher_number: 51 }),
+    })
+
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({
+      data: {
+        id: 'je-original',
+        status: 'posted',
+        fiscal_period_id: 'fp-1',
+        fiscal_periods: { is_closed: false },
+      },
+      error: null,
+    }) // executor's pre-flight fetch
+    enqueue({ data: null, error: null }) // dispatcher's commit update
+
+    const op = makePendingOp({
+      operation_type: 'correct_entry',
+      params: {
+        entry_id: 'je-original',
+        lines: [
+          { account_number: '2645', debit_amount: 250, credit_amount: 0 },
+          { account_number: '2614', debit_amount: 0, credit_amount: 250 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('committed')
+    expect(result.data).toMatchObject({
+      original_entry_id: 'je-original',
+      storno_entry_id: 'je-storno',
+      corrected_entry_id: 'je-corrected',
+      storno_voucher_number: 50,
+      corrected_voucher_number: 51,
+    })
+    expect(correctEntry).toHaveBeenCalledWith(
+      expect.anything(),
+      'company-1',
+      'user-1',
+      'je-original',
+      expect.arrayContaining([
+        expect.objectContaining({ account_number: '2645' }),
+        expect.objectContaining({ account_number: '2614' }),
+      ])
+    )
+  })
+
+  it('returns 404 when the original entry does not exist', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({ data: null, error: null }) // executor's pre-flight fetch (no row)
+    enqueue({ data: null, error: null }) // dispatcher's reject update
+
+    const op = makePendingOp({
+      operation_type: 'correct_entry',
+      params: {
+        entry_id: 'je-missing',
+        lines: [
+          { account_number: '5410', debit_amount: 100, credit_amount: 0 },
+          { account_number: '1930', debit_amount: 0, credit_amount: 100 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('rejected')
+    expect(result.auto_rejected).toBe(true)
+    expect(result.http_status).toBe(404)
+    expect(correctEntry).not.toHaveBeenCalled()
+  })
+
+  it('returns 409 when the original entry is not posted', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({
+      data: {
+        id: 'je-draft',
+        status: 'draft',
+        fiscal_period_id: 'fp-1',
+        fiscal_periods: { is_closed: false },
+      },
+      error: null,
+    }) // executor's pre-flight fetch
+    enqueue({ data: null, error: null }) // dispatcher's reject update
+
+    const op = makePendingOp({
+      operation_type: 'correct_entry',
+      params: {
+        entry_id: 'je-draft',
+        lines: [
+          { account_number: '5410', debit_amount: 100, credit_amount: 0 },
+          { account_number: '1930', debit_amount: 0, credit_amount: 100 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('rejected')
+    expect(result.http_status).toBe(409)
+    expect(result.error).toMatch(/bokförda verifikationer/)
+    expect(correctEntry).not.toHaveBeenCalled()
+  })
+
+  it('returns 409 with omprövning hint when the period is closed', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({
+      data: {
+        id: 'je-original',
+        status: 'posted',
+        fiscal_period_id: 'fp-1',
+        fiscal_periods: { is_closed: true },
+      },
+      error: null,
+    }) // executor's pre-flight fetch
+    enqueue({ data: null, error: null }) // dispatcher's reject update
+
+    const op = makePendingOp({
+      operation_type: 'correct_entry',
+      params: {
+        entry_id: 'je-original',
+        lines: [
+          { account_number: '5410', debit_amount: 100, credit_amount: 0 },
+          { account_number: '1930', debit_amount: 0, credit_amount: 100 },
+        ],
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('rejected')
+    expect(result.http_status).toBe(409)
+    expect(result.error).toMatch(/omprövning/i)
+    expect(correctEntry).not.toHaveBeenCalled()
+  })
+
+  it('returns 400 when required fields are missing', async () => {
+    const { supabase, enqueue } = createQueuedMockSupabase()
+    enqueue({ data: { id: 'op-1' }, error: null }) // CAS claim
+    enqueue({ data: null, error: null }) // dispatcher's reject update
+
+    const op = makePendingOp({
+      operation_type: 'correct_entry',
+      params: {
+        entry_id: 'je-1',
+        // missing lines
+      },
+    })
+
+    const result = await commitPendingOperation(supabase as never, 'user-1', 'company-1', op)
+
+    expect(result.status).toBe('failed')
+    expect(result.http_status).toBe(400)
+    expect(correctEntry).not.toHaveBeenCalled()
+  })
+})
diff --git a/lib/pending-operations/commit.ts b/lib/pending-operations/commit.ts
index 057d092e..81e24386 100644
--- a/lib/pending-operations/commit.ts
+++ b/lib/pending-operations/commit.ts
@@ -27,7 +27,8 @@ import {
   createInvoiceJournalEntry,
   createCreditNoteJournalEntry,
 } from '@/lib/bookkeeping/invoice-entries'
-import { reverseEntry } from '@/lib/bookkeeping/engine'
+import { createJournalEntry, findFiscalPeriod, reverseEntry, validateBalance } from '@/lib/bookkeeping/engine'
+import { correctEntry } from '@/lib/core/bookkeeping/storno-service'
 import { closePeriod, lockPeriod, unlockPeriod } from '@/lib/core/bookkeeping/period-service'
 import {
   executeYearEndClosing,
@@ -64,6 +65,8 @@ import type {
   InvoiceItem,
   AccountingMethod,
   CreditNote,
+  CreateJournalEntryLineInput,
+  JournalEntrySourceType,
 } from '@/types'
 
 const log = createLogger('pending-operations/commit')
@@ -1592,6 +1595,171 @@ async function commitImportSie(
   }
 }
 
+// ── Phase 4: arbitrary-line bookkeeping primitives ───────────────
+
+/**
+ * Normalize raw JSON line input from pending_operations.params into the
+ * engine's typed line shape. Trusts shape because the MCP tool already
+ * validates via Zod before staging — defensive coercion only.
+ */
+function normalizeVoucherLines(raw: unknown): CreateJournalEntryLineInput[] {
+  if (!Array.isArray(raw)) return []
+  return raw.map((l) => {
+    const line = l as Record<string, unknown>
+    return {
+      account_number: String(line.account_number),
+      debit_amount: Number(line.debit_amount) || 0,
+      credit_amount: Number(line.credit_amount) || 0,
+      line_description: line.line_description ? String(line.line_description) : undefined,
+      currency: line.currency ? String(line.currency) : undefined,
+      amount_in_currency: line.amount_in_currency !== undefined ? Number(line.amount_in_currency) : undefined,
+      exchange_rate: line.exchange_rate !== undefined ? Number(line.exchange_rate) : undefined,
+      tax_code: line.tax_code ? String(line.tax_code) : undefined,
+      cost_center: line.cost_center ? String(line.cost_center) : undefined,
+      project: line.project ? String(line.project) : undefined,
+    }
+  })
+}
+
+async function commitCreateVoucher(
+  supabase: SupabaseClient,
+  userId: string,
+  companyId: string,
+  params: Record<string, unknown>
+): Promise<ExecutorResult> {
+  const entryDate = params.entry_date as string
+  const description = params.description as string
+  const lines = normalizeVoucherLines(params.lines)
+
+  if (!entryDate || !description || lines.length < 2) {
+    return { error: 'entry_date, description, and at least two lines are required', status: 400 }
+  }
+
+  // Re-validate balance defensively. The MCP tool already checks before
+  // staging, but a tampered or hand-inserted pending_operations row would
+  // bypass that gate. createDraftEntry runs the same check internally — this
+  // is for a cleaner 400 + Swedish error before reaching the engine.
+  const balance = validateBalance(lines)
+  if (!balance.valid) {
+    return {
+      error: `Verifikationen balanserar inte: debet ${balance.totalDebit} SEK, kredit ${balance.totalCredit} SEK.`,
+      status: 400,
+    }
+  }
+
+  // Resolve fiscal period: prefer explicit, fall back to date lookup so the
+  // caller can post a voucher without first calling list_fiscal_periods.
+  let fiscalPeriodId = params.fiscal_period_id as string | undefined
+  if (!fiscalPeriodId) {
+    const resolved = await findFiscalPeriod(supabase, companyId, entryDate)
+    if (!resolved) {
+      return {
+        error: `Ingen öppen räkenskapsperiod täcker datumet ${entryDate}. Öppna en period eller välj ett annat datum.`,
+        status: 400,
+      }
+    }
+    fiscalPeriodId = resolved
+  }
+
+  try {
+    const entry = await createJournalEntry(
+      supabase,
+      companyId,
+      userId,
+      {
+        fiscal_period_id: fiscalPeriodId,
+        entry_date: entryDate,
+        description,
+        // source_type is hardcoded — never trust params.source_type. The MCP
+        // tool stages 'manual', but a future direct-staging path could
+        // otherwise inject 'bank'/'invoice'/etc. and corrupt audit attribution.
+        source_type: 'manual' as JournalEntrySourceType,
+        voucher_series: (params.voucher_series as string) || undefined,
+        notes: (params.notes as string) || undefined,
+        lines,
+      },
+      'mcp_create_voucher'
+    )
+
+    return {
+      data: {
+        journal_entry_id: entry.id,
+        voucher_number: entry.voucher_number,
+        voucher_series: entry.voucher_series,
+        fiscal_period_id: fiscalPeriodId,
+      },
+    }
+  } catch (err) {
+    if (isBookkeepingError(err)) throw err
+    return { error: err instanceof Error ? err.message : 'Failed to create voucher', status: 500 }
+  }
+}
+
+async function commitCorrectEntry(
+  supabase: SupabaseClient,
+  userId: string,
+  companyId: string,
+  params: Record<string, unknown>
+): Promise<ExecutorResult> {
+  const entryId = params.entry_id as string
+  const lines = normalizeVoucherLines(params.lines)
+
+  if (!entryId || lines.length < 2) {
+    return { error: 'entry_id and at least two lines are required', status: 400 }
+  }
+
+  // Pre-flight: verify the original is posted and its period is not locked.
+  // Falling into correctEntry without this returns a less helpful DB error and
+  // half-creates the storno before rolling back; surfacing the Swedish message
+  // here matches the period_locked UX everywhere else in the app.
+  const { data: original, error: origErr } = await supabase
+    .from('journal_entries')
+    .select('id, status, fiscal_period_id, fiscal_periods!inner(is_closed)')
+    .eq('id', entryId)
+    .eq('company_id', companyId)
+    .maybeSingle()
+
+  if (origErr || !original) {
+    return { error: 'Verifikationen hittades inte.', status: 404 }
+  }
+  if (original.status !== 'posted') {
+    return {
+      error: `Endast bokförda verifikationer kan rättas. Aktuell status: ${original.status}. Drafts redigeras direkt.`,
+      status: 409,
+    }
+  }
+  const period = original.fiscal_periods as { is_closed?: boolean } | { is_closed?: boolean }[] | null
+  const periodClosed = Array.isArray(period) ? period[0]?.is_closed : period?.is_closed
+  if (periodClosed) {
+    return {
+      error: 'Räkenskapsperioden är låst. Öppna perioden eller använd omprövning för redan inlämnade momsdeklarationer.',
+      status: 409,
+    }
+  }
+
+  try {
+    // correctEntry() posts both the storno and the corrected entry into the
+    // SAME fiscal_period_id and entry_date as the original (see
+    // lib/core/bookkeeping/storno-service.ts:99,102,195,198). So a rättelse
+    // made in May 2026 for a December 2025 voucher correctly lands in 2025,
+    // keeping that period's balances consistent. The is_closed pre-flight
+    // above is what blocks corrections to already-locked periods.
+    const result = await correctEntry(supabase, companyId, userId, entryId, lines)
+    return {
+      data: {
+        original_entry_id: entryId,
+        storno_entry_id: result.reversal.id,
+        corrected_entry_id: result.corrected.id,
+        storno_voucher_number: result.reversal.voucher_number,
+        corrected_voucher_number: result.corrected.voucher_number,
+      },
+    }
+  } catch (err) {
+    if (isBookkeepingError(err)) throw err
+    return { error: err instanceof Error ? err.message : 'Failed to correct entry', status: 500 }
+  }
+}
+
 // ── Public dispatcher ────────────────────────────────────────────
 
 /**
@@ -1703,6 +1871,12 @@ export async function commitPendingOperation(
       case 'import_sie':
         result = await commitImportSie(supabase, userId, companyId, pendingOp.params)
         break
+      case 'create_voucher':
+        result = await commitCreateVoucher(supabase, userId, companyId, pendingOp.params)
+        break
+      case 'correct_entry':
+        result = await commitCorrectEntry(supabase, userId, companyId, pendingOp.params)
+        break
       default:
         return {
           status: 'failed',
diff --git a/lib/pending-operations/risk-tiers.ts b/lib/pending-operations/risk-tiers.ts
index 1aefd51a..d12c64eb 100644
--- a/lib/pending-operations/risk-tiers.ts
+++ b/lib/pending-operations/risk-tiers.ts
@@ -57,6 +57,13 @@ export const OPERATION_RISK_TIERS: Record<string, RiskLevel> = {
   create_supplier_invoice_from_inbox: 'medium',
   credit_invoice: 'high',
   convert_invoice: 'medium',
+
+  // ── Phase 4: arbitrary-line bookkeeping primitives ─────────────────
+  // Both accept caller-supplied account/amount/period — unlike
+  // uncategorize_transaction (medium), which mirrors an existing entry.
+  // The arbitrary-line capability is what makes these compliance-critical.
+  create_voucher: 'high',
+  correct_entry: 'high',
 }
 
 export function getRiskLevel(operationType: string): RiskLevel {
diff --git a/supabase/migrations/20260512135110_pending_operations_expand_types_phase4.sql b/supabase/migrations/20260512135110_pending_operations_expand_types_phase4.sql
new file mode 100644
index 00000000..d916bc1b
--- /dev/null
+++ b/supabase/migrations/20260512135110_pending_operations_expand_types_phase4.sql
@@ -0,0 +1,59 @@
+-- Phase 4: expose the bookkeeping engine's arbitrary-line primitives via MCP.
+--
+-- Until now the only way to produce a journal entry via MCP was through a
+-- preset workflow (categorize_transaction, create_invoice, ...). That blocks
+-- legitimate flows the engine already supports — capitalization to balance-
+-- sheet accounts (BAS 1010 development costs under K3), period-end accruals,
+-- FX adjustments outside the built-in revaluation, prepayments, manual
+-- reclassifications, and rättelseposter for foreign reverse-charge VAT.
+--
+-- Two new op types:
+--   * create_voucher — arbitrary balanced lines via createJournalEntry()
+--   * correct_entry  — storno + replacement via correctEntry() (BFL 5 kap 5§)
+--
+-- Both are routed as HIGH risk in lib/pending-operations/risk-tiers.ts because
+-- they accept arbitrary account/amount/period inputs, unlike
+-- uncategorize_transaction which mirrors an existing entry's shape.
+
+ALTER TABLE public.pending_operations
+  DROP CONSTRAINT IF EXISTS pending_operations_operation_type_check;
+
+ALTER TABLE public.pending_operations
+  ADD CONSTRAINT pending_operations_operation_type_check
+  CHECK (operation_type IN (
+    -- Phase 0: original 7 op types
+    'categorize_transaction',
+    'create_customer',
+    'create_invoice',
+    'mark_invoice_paid',
+    'send_invoice',
+    'mark_invoice_sent',
+    'match_transaction_invoice',
+    -- Stream 1 Phase 1: bookkeeping period operations
+    'close_period',
+    'lock_period',
+    'unlock_period',
+    'set_opening_balances',
+    'run_year_end',
+    'run_currency_revaluation',
+    -- Stream 1 Phase 1: SIE import (export is read-only)
+    'import_sie',
+    -- Stream 1 Phase 1: voucher gap explanations
+    'explain_voucher_gap',
+    -- Stream 1 Phase 1: transaction reversal
+    'uncategorize_transaction',
+    -- Stream 1 Phase 1: supplier invoice lifecycle
+    'approve_supplier_invoice',
+    'credit_supplier_invoice',
+    -- Stream 1 Phase 1: invoice operations beyond simple create/send
+    'credit_invoice',
+    'convert_invoice',
+    -- Phase 3: manual transaction ingestion + document attachment
+    'create_transaction',
+    'attach_document_to_transaction',
+    -- Phase 4: arbitrary-line bookkeeping primitives (this migration)
+    'create_voucher',
+    'correct_entry'
+  ));
+
+NOTIFY pgrst, 'reload schema';
diff --git a/types/index.ts b/types/index.ts
index d1f75c31..53756b3b 100644
--- a/types/index.ts
+++ b/types/index.ts
@@ -1333,6 +1333,9 @@ export type PendingOperationType =
   // Stream 1 Phase 1: invoice operations beyond simple create/send
   | 'credit_invoice'
   | 'convert_invoice'
+  // Phase 4: arbitrary-line bookkeeping primitives
+  | 'create_voucher'
+  | 'correct_entry'
 export type PendingOperationStatus = 'pending' | 'committing' | 'committed' | 'rejected'
 
 export type PendingOperationActorType = 'user' | 'api_key' | 'mcp_oauth' | 'cron'