feat(salary): öresavrundning of net pay to whole kronor (#1609)

* feat(salary): öresavrundning of net pay to whole kronor

Some banks reject salary payment files whose amounts carry öre. New
company_settings.salary_net_rounding toggle (off by default): the engine
rounds each net payout up to the next whole krona, never down, and emits
a derived oresavrundning line item (semesterersattning pattern) that
debits 3740 Öres- och kronutjämning so the salary entry stays balanced.
Gross, tax and avgifter are untouched, so AGI/KU are unaffected. Payment
files (pain.001 + Bankgirot LB) get whole-krona amounts via the rounded
net_salary. Toggle in salary settings; payslip and run detail show the
line item.

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

* fix(salary): keep employer cost on the shared definition; block manual rounding lines

Skeptic findings on the öresavrundning commit: (1) the engine included
netRounding in totalEmployerCost while payslip summary, KPI cards and
lönejournal recompute the figure from stored columns, printing two
different totals on the same payslip; employer cost now stays on the
shared definition and the öre cost is carried by the 3740 ledger line.
(2) 'oresavrundning' is excluded from the line-item create/update
schemas: it is the only item type the booking keeps out of the gross
reconciliation, so a manually created row would structurally unbalance
the salary verifikat.

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

* fix(salary): add the item_type CHECK as NOT VALID, validate separately

Compliance-swarm finding (SOC 2 CC8.1): the CHECK re-add scanned
salary_line_items under the ADD's ACCESS EXCLUSIVE lock. Split per the
house pattern (DECISIONS.md 2026-07-13): 20260813143000 re-adds the
constraint NOT VALID, new 20260813143001 validates it under SHARE UPDATE
EXCLUSIVE in its own transaction. The list is a strict superset of the
previous CHECK, so validation cannot fail. Both files are branch-only,
so editing in place is within the never-modify-shipped rule.

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

---------

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

lib/api/__tests__/schemas.test.ts

@@ -2815,3 +2815,22 @@ describe('CreateRecurringScheduleSchema interval_months', () => {
     expect(CreateRecurringScheduleSchema.safeParse({ ...base, interval_months: 1.5 }).success).toBe(false)
   })
 })
+
+describe('CreateSalaryLineItemSchema: derived-only item types', () => {
+  it("rejects manual 'oresavrundning' lines (only the calculator may write them)", async () => {
+    const { CreateSalaryLineItemSchema, UpdateSalaryLineItemSchema } = await import('../schemas')
+    const base = {
+      salary_run_employee_id: '3f0a2f60-0000-4000-8000-000000000001',
+      description: 'Öresavrundning',
+      amount: 0.4,
+    }
+    expect(
+      CreateSalaryLineItemSchema.safeParse({ ...base, item_type: 'oresavrundning' }).success,
+    ).toBe(false)
+    expect(
+      CreateSalaryLineItemSchema.safeParse({ ...base, item_type: 'bonus' }).success,
+    ).toBe(true)
+    expect(UpdateSalaryLineItemSchema.safeParse({ item_type: 'oresavrundning' }).success).toBe(false)
+    expect(UpdateSalaryLineItemSchema.safeParse({ item_type: 'bonus' }).success).toBe(true)
+  })
+})

lib/api/schemas.ts

@@ -2014,6 +2014,9 @@ export const UpdateSettingsSchema = z.object({
     .enum(['swedbank', 'seb', 'handelsbanken', 'nordea', 'other'])
     .nullable()
     .optional(),
+  // Öresavrundning: round each net payout up to whole kronor (banks that
+  // reject öre in salary payment files). Diff books on 3740.
+  salary_net_rounding: z.boolean().optional(),
   // Vacation year basis (payroll gap-closure 3.1): sammanfallande calendar
   // year (default) or the statutory Apr 1 - Mar 31 split. The settings route
   // blocks changing this while open vacation-ledger rows exist.
@@ -2514,6 +2517,7 @@ export const SalaryLineItemTypeSchema = z.enum([
   'mileage_taxfree', 'mileage_taxable',
   'net_deduction_advance', 'net_deduction_union', 'net_deduction_benefit_payment',
   'net_deduction_other',
+  'oresavrundning',
   'correction', 'other',
 ])
 
@@ -2893,7 +2897,13 @@ export const AddEmployeeToRunSchema = z.object({
 
 export const CreateSalaryLineItemSchema = z.object({
   salary_run_employee_id: uuid,
-  item_type: SalaryLineItemTypeSchema,
+  // 'oresavrundning' is derived-only: the calculator writes it from the
+  // engine's netRounding and the booking excludes it from the gross
+  // reconciliation, so a manually created row would unbalance the salary
+  // verifikat by exactly its amount (the DB balance trigger then rejects the
+  // booking). Every other derived type is absorbed by the base remainder and
+  // stays harmless to create by hand.
+  item_type: SalaryLineItemTypeSchema.exclude(['oresavrundning']),
   description: z.string().min(1).max(500),
   quantity: z.number().optional(),
   unit_price: z.number().optional(),