fix(money): zero-decimal currency handling (D7)

Stripe sends zero-decimal currencies (JPY/KRW/VND/...) already in the
major unit; the unconditional /100 recorded a JPY dues charge 100x
understated in the ledger + receipt. minorToMajor is now currency-aware
(shared ZERO_DECIMAL_CURRENCIES/isZeroDecimalCurrency in
notifications-logic); formatMoney renders no fractional part for those.
Never fires for USD; closes silent ledger corruption for such tenants.
Tests added; suite 526+.

__tests__/notifications-logic.test.ts

@@ -85,6 +85,10 @@ describe('formatMoney', () => {
     expect(formatMoney(undefined, 'usd')).toBe('')
     expect(formatMoney(NaN, 'usd')).toBe('')
   })
+  it('renders zero-decimal currencies with no fractional part', () => {
+    expect(formatMoney(3000, 'jpy')).toBe('3000 JPY')
+    expect(formatMoney(50000, 'KRW')).toBe('50000 KRW')
+  })
 })
 
 describe('renderDuesEmail', () => {

__tests__/stripe-webhook-logic.test.ts

@@ -140,10 +140,16 @@ describe('laterPeriodEnd (never rewind on out-of-order events)', () => {
   })
 })
 
-describe('minorToMajor', () => {
-  it('divides by 100, treats nullish as 0', () => {
-    expect(minorToMajor(2500)).toBe(25)
-    expect(minorToMajor(null)).toBe(0)
-    expect(minorToMajor(undefined)).toBe(0)
+describe('minorToMajor (currency-aware)', () => {
+  it('divides by 100 for normal 2-decimal currencies', () => {
+    expect(minorToMajor(2500, 'usd')).toBe(25)
+    expect(minorToMajor(2500, 'EUR')).toBe(25)
+    expect(minorToMajor(null, 'usd')).toBe(0)
+    expect(minorToMajor(undefined, undefined)).toBe(0)
+  })
+  it('does NOT divide zero-decimal currencies (JPY/KRW already major)', () => {
+    expect(minorToMajor(3000, 'jpy')).toBe(3000)
+    expect(minorToMajor(50000, 'KRW')).toBe(50000)
+    expect(minorToMajor(1000, 'VND')).toBe(1000)
   })
 })

app/api/stripe/webhook/[space]/route.ts

@@ -298,7 +298,7 @@ export async function POST(
         await enqueueDues('dues_renewed', {
           memberId,
           fallbackEmail: inv.customer_email ?? null,
-          amount: minorToMajor(inv.amount_paid),
+          amount: minorToMajor(inv.amount_paid, inv.currency),
           currency: (inv.currency ?? 'usd').toUpperCase(),
           periodEnd: invoiceLinePeriodEnd(inv),
           invoiceId: inv.id,
@@ -317,7 +317,7 @@ export async function POST(
         await enqueueDues('dues_payment_failed', {
           memberId,
           fallbackEmail: inv.customer_email ?? null,
-          amount: minorToMajor(inv.amount_due),
+          amount: minorToMajor(inv.amount_due, inv.currency),
           currency: (inv.currency ?? 'usd').toUpperCase(),
           invoiceId: inv.id,
         })

lib/notifications-logic.ts

@@ -72,8 +72,20 @@ function escapeHtml(s: string): string {
 
 const CURRENCY_SYMBOL: Record<string, string> = { USD: '$', CAD: '$', EUR: '€', GBP: '£' }
 
-// amount is in major units (dollars), matching how the payments ledger stores
-// it (Stripe minor units are divided by 100 by the caller).
+// Stripe zero-decimal currencies: the smallest unit IS the major unit, so
+// amounts are NOT scaled by 100 and have no fractional display. Source:
+// Stripe "zero-decimal currencies" list.
+export const ZERO_DECIMAL_CURRENCIES = new Set([
+  'BIF', 'CLP', 'DJF', 'GNF', 'JPY', 'KMF', 'KRW', 'MGA', 'PYG', 'RWF',
+  'UGX', 'VND', 'VUV', 'XAF', 'XOF', 'XPF',
+])
+
+export function isZeroDecimalCurrency(currency: string | null | undefined): boolean {
+  return ZERO_DECIMAL_CURRENCIES.has((currency || 'USD').toUpperCase())
+}
+
+// amount is in major units, matching how the payments ledger stores it.
+// Zero-decimal currencies render with no fractional part.
 export function formatMoney(
   amount: number | null | undefined,
   currency: string | null | undefined,
@@ -81,7 +93,7 @@ export function formatMoney(
   if (amount === null || amount === undefined || Number.isNaN(amount)) return ''
   const code = (currency || 'USD').toUpperCase()
   const sym = CURRENCY_SYMBOL[code]
-  const n = amount.toFixed(2)
+  const n = isZeroDecimalCurrency(code) ? String(Math.round(amount)) : amount.toFixed(2)
   return sym ? `${sym}${n} ${code}` : `${n} ${code}`
 }
 

lib/stripe/webhook-logic.ts

@@ -7,6 +7,8 @@
 // around it, including the Stripe Basil (2025-03-31 / 2026-04-22.dahlia)
 // field relocations that are easy to get wrong and must be tested.
 
+import { isZeroDecimalCurrency } from '@/lib/notifications-logic'
+
 type CustomerRef = string | { id?: string | null } | null | undefined
 
 type SubscriptionLike = {
@@ -81,7 +83,7 @@ export function stripeInvoiceToPaymentRow(args: {
     space_id: spaceId,
     member_id: memberId,
     platform: 'stripe' as const,
-    amount: (inv.amount_paid ?? 0) / 100,
+    amount: minorToMajor(inv.amount_paid, inv.currency),
     currency: (inv.currency ?? 'usd').toUpperCase(),
     description: inv.description ?? 'Stripe membership dues',
     status: linked,
@@ -94,10 +96,15 @@ export function stripeInvoiceToPaymentRow(args: {
   }
 }
 
-// Major-units amount for the dues email (amount_paid for renewals,
-// amount_due for failed-payment notices).
-export function minorToMajor(amount: number | null | undefined): number {
-  return (amount ?? 0) / 100
+// Stripe sends most amounts in minor units (cents) but zero-decimal
+// currencies (JPY, KRW, ...) already in the major unit — dividing those by
+// 100 would understate the ledger + receipt 100x. Currency-aware.
+export function minorToMajor(
+  amount: number | null | undefined,
+  currency: string | null | undefined,
+): number {
+  const a = amount ?? 0
+  return isZeroDecimalCurrency(currency) ? a : a / 100
 }
 
 // Stripe does not guarantee webhook ordering. A stale/late