Convert display prices on current rates

bruno/currency-rates/historical-usd.bru

@@ -0,0 +1,18 @@
+meta {
+  name: Historical USD rates
+  type: http
+  seq: 2
+}
+
+get {
+  url: https://v6.exchangerate-api.com/v6/{{exchangeRateApiKey}}/history/USD/{{year}}/{{month}}/{{day}}
+  body: none
+  auth: none
+}
+
+assert {
+  res.status: eq 200
+  res.body.result: eq success
+  res.body.base_code: eq USD
+  res.body.conversion_rates.USD: eq 1
+}

prisma/migrations/3_add_currency_rate_history/migration.sql

@@ -0,0 +1,116 @@
+-- CreateTable
+CREATE TABLE "exchange_currency_rate_snapshots" (
+    "id" SERIAL NOT NULL,
+    "uuid" TEXT NOT NULL,
+    "base_currency" VARCHAR(3) NOT NULL,
+    "effective_date" DATE NOT NULL,
+    "quoted_at" TIMESTAMP(3) NOT NULL,
+    "next_update_at" TIMESTAMP(3),
+    "provider" VARCHAR(255) NOT NULL,
+    "documentation" VARCHAR(500) NOT NULL,
+    "terms_of_use" VARCHAR(500) NOT NULL,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "exchange_currency_rate_snapshots_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "exchange_currency_rates" (
+    "id" SERIAL NOT NULL,
+    "snapshot_id" INTEGER NOT NULL,
+    "quote_currency" VARCHAR(3) NOT NULL,
+    "rate" DECIMAL(24,10) NOT NULL,
+
+    CONSTRAINT "exchange_currency_rates_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "exchange_pricing_currency_policies" (
+    "country_code" VARCHAR(2) NOT NULL,
+    "currency_code" VARCHAR(3) NOT NULL,
+    "updated_at" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "exchange_pricing_currency_policies_pkey" PRIMARY KEY ("country_code")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "exchange_currency_rate_snapshots_uuid_key" ON "exchange_currency_rate_snapshots"("uuid");
+
+-- CreateIndex
+CREATE INDEX "exchange_currency_rate_snapshots_effective_date_idx" ON "exchange_currency_rate_snapshots"("effective_date");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "exchange_currency_rate_snapshots_base_currency_effective_da_key" ON "exchange_currency_rate_snapshots"("base_currency", "effective_date");
+
+-- CreateIndex
+CREATE INDEX "exchange_currency_rates_quote_currency_idx" ON "exchange_currency_rates"("quote_currency");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "exchange_currency_rates_snapshot_id_quote_currency_key" ON "exchange_currency_rates"("snapshot_id", "quote_currency");
+
+-- CreateIndex
+CREATE INDEX "exchange_pricing_currency_policies_currency_code_idx" ON "exchange_pricing_currency_policies"("currency_code");
+
+-- AddForeignKey
+ALTER TABLE "exchange_currency_rates" ADD CONSTRAINT "exchange_currency_rates_snapshot_id_fkey" FOREIGN KEY ("snapshot_id") REFERENCES "exchange_currency_rate_snapshots"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- Seed pricing currencies for countries already present in Optovia data.
+INSERT INTO "exchange_pricing_currency_policies" ("country_code", "currency_code", "updated_at") VALUES
+  ('AE', 'AED', CURRENT_TIMESTAMP),
+  ('AO', 'AOA', CURRENT_TIMESTAMP),
+  ('BF', 'XOF', CURRENT_TIMESTAMP),
+  ('BI', 'BIF', CURRENT_TIMESTAMP),
+  ('BJ', 'XOF', CURRENT_TIMESTAMP),
+  ('BW', 'BWP', CURRENT_TIMESTAMP),
+  ('CD', 'CDF', CURRENT_TIMESTAMP),
+  ('CF', 'XAF', CURRENT_TIMESTAMP),
+  ('CG', 'XAF', CURRENT_TIMESTAMP),
+  ('CI', 'XOF', CURRENT_TIMESTAMP),
+  ('CM', 'XAF', CURRENT_TIMESTAMP),
+  ('CN', 'CNY', CURRENT_TIMESTAMP),
+  ('CV', 'CVE', CURRENT_TIMESTAMP),
+  ('DJ', 'DJF', CURRENT_TIMESTAMP),
+  ('DZ', 'DZD', CURRENT_TIMESTAMP),
+  ('EG', 'EGP', CURRENT_TIMESTAMP),
+  ('ET', 'ETB', CURRENT_TIMESTAMP),
+  ('GA', 'XAF', CURRENT_TIMESTAMP),
+  ('GH', 'GHS', CURRENT_TIMESTAMP),
+  ('GM', 'GMD', CURRENT_TIMESTAMP),
+  ('GN', 'GNF', CURRENT_TIMESTAMP),
+  ('GQ', 'XAF', CURRENT_TIMESTAMP),
+  ('GW', 'XOF', CURRENT_TIMESTAMP),
+  ('KE', 'KES', CURRENT_TIMESTAMP),
+  ('KM', 'KMF', CURRENT_TIMESTAMP),
+  ('KZ', 'KZT', CURRENT_TIMESTAMP),
+  ('LR', 'LRD', CURRENT_TIMESTAMP),
+  ('LS', 'LSL', CURRENT_TIMESTAMP),
+  ('LY', 'LYD', CURRENT_TIMESTAMP),
+  ('MA', 'MAD', CURRENT_TIMESTAMP),
+  ('MG', 'MGA', CURRENT_TIMESTAMP),
+  ('ML', 'XOF', CURRENT_TIMESTAMP),
+  ('MR', 'MRU', CURRENT_TIMESTAMP),
+  ('MU', 'MUR', CURRENT_TIMESTAMP),
+  ('MW', 'MWK', CURRENT_TIMESTAMP),
+  ('MZ', 'MZN', CURRENT_TIMESTAMP),
+  ('NA', 'NAD', CURRENT_TIMESTAMP),
+  ('NE', 'XOF', CURRENT_TIMESTAMP),
+  ('NG', 'NGN', CURRENT_TIMESTAMP),
+  ('PL', 'PLN', CURRENT_TIMESTAMP),
+  ('RU', 'RUB', CURRENT_TIMESTAMP),
+  ('RW', 'RWF', CURRENT_TIMESTAMP),
+  ('SC', 'SCR', CURRENT_TIMESTAMP),
+  ('SD', 'SDG', CURRENT_TIMESTAMP),
+  ('SL', 'SLE', CURRENT_TIMESTAMP),
+  ('SN', 'XOF', CURRENT_TIMESTAMP),
+  ('SO', 'SOS', CURRENT_TIMESTAMP),
+  ('SS', 'SSP', CURRENT_TIMESTAMP),
+  ('ST', 'STN', CURRENT_TIMESTAMP),
+  ('SZ', 'SZL', CURRENT_TIMESTAMP),
+  ('TD', 'XAF', CURRENT_TIMESTAMP),
+  ('TG', 'XOF', CURRENT_TIMESTAMP),
+  ('TN', 'TND', CURRENT_TIMESTAMP),
+  ('TZ', 'TZS', CURRENT_TIMESTAMP),
+  ('UG', 'UGX', CURRENT_TIMESTAMP),
+  ('ZA', 'ZAR', CURRENT_TIMESTAMP),
+  ('ZM', 'ZMW', CURRENT_TIMESTAMP),
+  ('ZW', 'ZWG', CURRENT_TIMESTAMP);

prisma/migrations/4_seed_demo_currency_rates/migration.sql

@@ -0,0 +1,37 @@
+-- Seed the fixed 2026-08-24 demo snapshot. Runtime pricing reads only this table.
+INSERT INTO "exchange_currency_rate_snapshots" (
+    "uuid",
+    "base_currency",
+    "effective_date",
+    "quoted_at",
+    "next_update_at",
+    "provider",
+    "documentation",
+    "terms_of_use"
+)
+VALUES (
+    '00000000-0000-4000-8000-202608240001',
+    'USD',
+    DATE '2026-08-24',
+    TIMESTAMP '2026-08-24 00:02:31',
+    NULL,
+    'demo-fixed',
+    'internal demo snapshot',
+    'demo only'
+)
+ON CONFLICT ("base_currency", "effective_date") DO NOTHING;
+
+INSERT INTO "exchange_currency_rates" ("snapshot_id", "quote_currency", "rate")
+SELECT snapshot."id", rate."quote_currency", rate."rate"
+FROM "exchange_currency_rate_snapshots" AS snapshot
+CROSS JOIN (
+    VALUES
+      ('USD', 1.0000000000::DECIMAL(24,10)),
+      ('RUB', 82.8028650000::DECIMAL(24,10)),
+      ('CNY', 6.7291140000::DECIMAL(24,10)),
+      ('EUR', 0.8561800000::DECIMAL(24,10)),
+      ('AED', 3.6725000000::DECIMAL(24,10))
+) AS rate("quote_currency", "rate")
+WHERE snapshot."base_currency" = 'USD'
+  AND snapshot."effective_date" = DATE '2026-08-24'
+ON CONFLICT ("snapshot_id", "quote_currency") DO NOTHING;

prisma/migrations/5_remove_country_currency_policy/migration.sql

@@ -0,0 +1,2 @@
+-- DropTable
+DROP TABLE "exchange_pricing_currency_policies";

prisma/schema.prisma

@@ -69,3 +69,33 @@ model Product {
   @@index([categoryName, isActive])
   @@map("exchange_products")
 }
+
+model CurrencyRateSnapshot {
+  id            Int            @id @default(autoincrement())
+  uuid          String         @unique @default(uuid())
+  baseCurrency  String         @map("base_currency") @db.VarChar(3)
+  effectiveDate DateTime       @map("effective_date") @db.Date
+  quotedAt      DateTime       @map("quoted_at")
+  nextUpdateAt  DateTime?      @map("next_update_at")
+  provider      String         @db.VarChar(255)
+  documentation String         @db.VarChar(500)
+  termsOfUse    String         @map("terms_of_use") @db.VarChar(500)
+  createdAt     DateTime       @default(now()) @map("created_at")
+  rates         CurrencyRate[]
+
+  @@unique([baseCurrency, effectiveDate])
+  @@index([effectiveDate])
+  @@map("exchange_currency_rate_snapshots")
+}
+
+model CurrencyRate {
+  id            Int                  @id @default(autoincrement())
+  snapshotId    Int                  @map("snapshot_id")
+  snapshot      CurrencyRateSnapshot @relation(fields: [snapshotId], references: [id], onDelete: Cascade)
+  quoteCurrency String               @map("quote_currency") @db.VarChar(3)
+  rate          Decimal              @db.Decimal(24, 10)
+
+  @@unique([snapshotId, quoteCurrency])
+  @@index([quoteCurrency])
+  @@map("exchange_currency_rates")
+}

src/currency-rate-store.ts

@@ -0,0 +1,143 @@
+import { Prisma } from '@prisma/client'
+
+import { prisma } from './db.js'
+import {
+  currencyCode,
+  type CurrencyRatesSnapshot,
+} from './currency-rates.js'
+
+const snapshotInclude = {
+  rates: true,
+} satisfies Prisma.CurrencyRateSnapshotInclude
+
+type StoredSnapshot = Prisma.CurrencyRateSnapshotGetPayload<{
+  include: typeof snapshotInclude
+}>
+
+export type StoredCurrencyRatesSnapshot = CurrencyRatesSnapshot & {
+  uuid: string
+  effectiveDate: Date
+}
+
+function utcDate(value: Date): Date {
+  return new Date(Date.UTC(value.getUTCFullYear(), value.getUTCMonth(), value.getUTCDate()))
+}
+
+function snapshotFromStored(item: StoredSnapshot): StoredCurrencyRatesSnapshot {
+  return {
+    uuid: item.uuid,
+    baseCurrency: 'USD',
+    effectiveDate: item.effectiveDate,
+    rates: Object.fromEntries(
+      item.rates.map(rate => [rate.quoteCurrency, Number(rate.rate)]),
+    ),
+    updatedAt: item.quotedAt,
+    nextUpdateAt: item.nextUpdateAt ?? item.quotedAt,
+    provider: item.provider,
+    documentation: item.documentation,
+    termsOfUse: item.termsOfUse,
+    attributionUrl: item.provider === 'demo-fixed'
+      ? null
+      : 'https://www.exchangerate-api.com',
+  }
+}
+
+function rateRows(snapshot: CurrencyRatesSnapshot) {
+  return Object.entries(snapshot.rates).map(([rawCurrency, rate]) => {
+    const quoteCurrency = currencyCode(rawCurrency)
+    if (!Number.isFinite(rate) || rate <= 0) {
+      throw new Error(`Invalid ${quoteCurrency} exchange rate: ${rate}`)
+    }
+    return {
+      quoteCurrency,
+      rate: new Prisma.Decimal(rate),
+    }
+  })
+}
+
+async function findStored(effectiveDate: Date): Promise<StoredSnapshot | null> {
+  return prisma.currencyRateSnapshot.findUnique({
+    where: {
+      baseCurrency_effectiveDate: {
+        baseCurrency: 'USD',
+        effectiveDate,
+      },
+    },
+    include: snapshotInclude,
+  })
+}
+
+async function findLatestStored(): Promise<StoredSnapshot | null> {
+  return prisma.currencyRateSnapshot.findFirst({
+    where: {
+      baseCurrency: 'USD',
+      effectiveDate: { lte: utcDate(new Date()) },
+    },
+    orderBy: { effectiveDate: 'desc' },
+    include: snapshotInclude,
+  })
+}
+
+export async function persistCurrencyRates(
+  snapshot: CurrencyRatesSnapshot,
+): Promise<StoredCurrencyRatesSnapshot> {
+  const effectiveDate = utcDate(snapshot.updatedAt)
+  const rows = rateRows(snapshot)
+  const stored = await prisma.$transaction(async transaction => {
+    const item = await transaction.currencyRateSnapshot.upsert({
+      where: {
+        baseCurrency_effectiveDate: {
+          baseCurrency: snapshot.baseCurrency,
+          effectiveDate,
+        },
+      },
+      create: {
+        baseCurrency: snapshot.baseCurrency,
+        effectiveDate,
+        quotedAt: snapshot.updatedAt,
+        nextUpdateAt: snapshot.nextUpdateAt,
+        provider: snapshot.provider,
+        documentation: snapshot.documentation,
+        termsOfUse: snapshot.termsOfUse,
+      },
+      update: {
+        quotedAt: snapshot.updatedAt,
+        nextUpdateAt: snapshot.nextUpdateAt,
+        provider: snapshot.provider,
+        documentation: snapshot.documentation,
+        termsOfUse: snapshot.termsOfUse,
+      },
+    })
+    await transaction.currencyRate.deleteMany({ where: { snapshotId: item.id } })
+    await transaction.currencyRate.createMany({
+      data: rows.map(row => ({ snapshotId: item.id, ...row })),
+    })
+    return transaction.currencyRateSnapshot.findUniqueOrThrow({
+      where: { id: item.id },
+      include: snapshotInclude,
+    })
+  })
+  return snapshotFromStored(stored)
+}
+
+export async function latestCurrencyRatesSnapshot(): Promise<StoredCurrencyRatesSnapshot> {
+  const stored = await findLatestStored()
+  if (stored === null) {
+    throw new Error('Fixed currency rate snapshot is not configured')
+  }
+  return snapshotFromStored(stored)
+}
+
+export async function currencyRatesSnapshotForDate(
+  requestedDate: Date,
+): Promise<StoredCurrencyRatesSnapshot> {
+  const effectiveDate = utcDate(requestedDate)
+  if (effectiveDate.getTime() > utcDate(new Date()).getTime()) {
+    throw new Error('Currency rate date cannot be in the future')
+  }
+  const stored = await findStored(effectiveDate)
+  if (stored !== null) return snapshotFromStored(stored)
+  throw new Error(
+    `Currency rate snapshot is not configured for ${effectiveDate.toISOString().slice(0, 10)}`,
+  )
+}

src/currency-rates.test.ts

@@ -1,16 +1,10 @@
 import assert from 'node:assert/strict'
 import test from 'node:test'
 
-import { convertMoney, displayCurrency, parseCurrencyRates } from './currency-rates.js'
+import { convertMoney, displayCurrency } from './currency-rates.js'
 
-const payload = {
-  result: 'success',
-  provider: 'https://www.exchangerate-api.com',
-  documentation: 'https://www.exchangerate-api.com/docs/free',
-  terms_of_use: 'https://www.exchangerate-api.com/terms',
-  time_last_update_unix: 1_787_529_751,
-  time_next_update_unix: 1_787_617_021,
-  base_code: 'USD',
+const snapshot = {
+  baseCurrency: 'USD' as const,
   rates: {
     USD: 1,
     RUB: 82.802865,
@@ -18,25 +12,29 @@ const payload = {
     EUR: 0.85618,
     AED: 3.6725,
   },
+  updatedAt: new Date('2026-08-24T00:00:00.000Z'),
+  nextUpdateAt: new Date('2026-08-24T00:00:00.000Z'),
+  provider: 'demo-fixed',
+  documentation: 'internal',
+  termsOfUse: 'demo',
+  attributionUrl: null,
 }
 
 test('converts USD into the selected display currency', () => {
-  const rates = parseCurrencyRates(payload)
-  assert.equal(convertMoney(100, 'USD', 'RUB', rates), 8_280.2865)
+  assert.equal(convertMoney(100, 'USD', 'RUB', snapshot), 8_280.2865)
 })
 
 test('converts between two non-USD currencies through the USD base', () => {
-  const rates = parseCurrencyRates(payload)
-  assert.equal(convertMoney(82.802865, 'RUB', 'EUR', rates), 0.85618)
+  assert.equal(convertMoney(82.802865, 'RUB', 'EUR', snapshot), 0.85618)
 })
 
 test('rejects unsupported display currencies', () => {
   assert.throws(() => displayCurrency('GBP'), /Unsupported display currency/)
 })
 
-test('rejects incomplete provider responses', () => {
+test('rejects snapshots without the requested rate', () => {
   assert.throws(
-    () => parseCurrencyRates({ ...payload, rates: { ...payload.rates, RUB: 0 } }),
-    /no valid RUB rate/,
+    () => convertMoney(100, 'USD', 'GBP', snapshot),
+    /No exchange rate for target currency: GBP/,
   )
 })

src/currency-rates.ts

@@ -2,18 +2,6 @@ export const DISPLAY_CURRENCIES = ['USD', 'RUB', 'CNY', 'EUR', 'AED'] as const
 
 export type DisplayCurrency = typeof DISPLAY_CURRENCIES[number]
 
-type ExchangeRateApiResponse = {
-  result?: string
-  provider?: string
-  documentation?: string
-  terms_of_use?: string
-  time_last_update_unix?: number
-  time_next_update_unix?: number
-  base_code?: string
-  rates?: Record<string, number>
-  'error-type'?: string
-}
-
 export type CurrencyRatesSnapshot = {
   baseCurrency: 'USD'
   rates: Record<string, number>
@@ -22,14 +10,11 @@ export type CurrencyRatesSnapshot = {
   provider: string
   documentation: string
   termsOfUse: string
-  attributionUrl: string
+  attributionUrl: string | null
 }
 
-const exchangeRateApiUrl = 'https://open.er-api.com/v6/latest/USD'
 const displayCurrencyCodes = new Set<string>(DISPLAY_CURRENCIES)
 
-let cachedRates: CurrencyRatesSnapshot | null = null
-
 export function displayCurrency(value: unknown): DisplayCurrency {
   const normalized = String(value ?? '').trim().toUpperCase()
   if (!displayCurrencyCodes.has(normalized)) {
@@ -38,53 +23,18 @@ export function displayCurrency(value: unknown): DisplayCurrency {
   return normalized as DisplayCurrency
 }
 
-export function parseCurrencyRates(payload: ExchangeRateApiResponse): CurrencyRatesSnapshot {
-  if (payload.result !== 'success') {
-    throw new Error(`ExchangeRate-API error: ${payload['error-type'] ?? payload.result ?? 'invalid response'}`)
+export function currencyCode(value: unknown): string {
+  const normalized = String(value ?? '').trim().toUpperCase()
+  if (!/^[A-Z]{3}$/.test(normalized)) {
+    throw new Error(`Invalid ISO 4217 currency code: ${normalized || 'empty'}`)
   }
-  if (payload.base_code !== 'USD') {
-    throw new Error(`ExchangeRate-API returned unexpected base currency: ${payload.base_code ?? 'empty'}`)
-  }
-  if (!payload.rates || !payload.time_last_update_unix || !payload.time_next_update_unix) {
-    throw new Error('ExchangeRate-API response is missing rates or update timestamps')
-  }
-  if (!payload.provider || !payload.documentation || !payload.terms_of_use) {
-    throw new Error('ExchangeRate-API response is missing attribution metadata')
-  }
-  for (const code of DISPLAY_CURRENCIES) {
-    const rate = payload.rates[code]
-    if (typeof rate !== 'number' || !Number.isFinite(rate) || rate <= 0) {
-      throw new Error(`ExchangeRate-API response has no valid ${code} rate`)
-    }
-  }
-  return {
-    baseCurrency: 'USD',
-    rates: payload.rates,
-    updatedAt: new Date(payload.time_last_update_unix * 1000),
-    nextUpdateAt: new Date(payload.time_next_update_unix * 1000),
-    provider: payload.provider,
-    documentation: payload.documentation,
-    termsOfUse: payload.terms_of_use,
-    attributionUrl: 'https://www.exchangerate-api.com',
-  }
-}
-
-export async function currencyRates(): Promise<CurrencyRatesSnapshot> {
-  if (cachedRates && Date.now() < cachedRates.nextUpdateAt.getTime()) {
-    return cachedRates
-  }
-  const response = await fetch(exchangeRateApiUrl)
-  if (!response.ok) {
-    throw new Error(`ExchangeRate-API request failed: ${response.status}`)
-  }
-  cachedRates = parseCurrencyRates(await response.json() as ExchangeRateApiResponse)
-  return cachedRates
+  return normalized
 }
 
 export function convertMoney(
   amount: number,
   sourceCurrency: string,
-  targetCurrency: DisplayCurrency,
+  targetCurrencyValue: string,
   snapshot: CurrencyRatesSnapshot,
 ) {
   if (!Number.isFinite(amount)) {
@@ -92,23 +42,27 @@ export function convertMoney(
   }
   const normalizedSource = sourceCurrency.trim().toUpperCase()
   const sourceRate = snapshot.rates[normalizedSource]
+  const targetCurrency = currencyCode(targetCurrencyValue)
   const targetRate = snapshot.rates[targetCurrency]
   if (typeof sourceRate !== 'number' || !Number.isFinite(sourceRate) || sourceRate <= 0) {
     throw new Error(`No exchange rate for source currency: ${normalizedSource || 'empty'}`)
   }
+  if (typeof targetRate !== 'number' || !Number.isFinite(targetRate) || targetRate <= 0) {
+    throw new Error(`No exchange rate for target currency: ${targetCurrency}`)
+  }
   return amount / sourceRate * targetRate
 }
 
 export async function convertPrices<T extends { pricePerUnit: unknown; currency: string }>(
   rows: T[],
   targetCurrencyValue: unknown,
+  snapshot: CurrencyRatesSnapshot,
 ) {
   const targetCurrency = displayCurrency(targetCurrencyValue)
   const needsConversion = rows.some(row => row.currency.trim().toUpperCase() !== targetCurrency)
   if (!needsConversion) {
     return rows.map(row => ({ ...row, pricePerUnit: Number(row.pricePerUnit), currency: targetCurrency }))
   }
-  const snapshot = await currencyRates()
   return rows.map(row => ({
     ...row,
     pricePerUnit: convertMoney(Number(row.pricePerUnit), row.currency, targetCurrency, snapshot),

src/index.ts

@@ -3,6 +3,7 @@ import cors from "@fastify/cors";
 import mercurius from "mercurius";
 import * as Sentry from "@sentry/node";
 import { resolvers, typeDefs } from "./schema.js";
+import { m2mResolvers, m2mTypeDefs } from "./m2m-schema.js";
 
 const PORT = Number.parseInt(process.env.PORT || "8000", 10);
 const SENTRY_DSN = process.env.SENTRY_DSN || "";
@@ -30,9 +31,21 @@ await app.register(mercurius, {
   path: "/graphql",
   graphiql: true,
 });
+await app.register(
+  async (route) => {
+    await route.register(mercurius, {
+      schema: m2mTypeDefs,
+      resolvers: m2mResolvers,
+      path: "/",
+      graphiql: false,
+    });
+  },
+  { prefix: "/graphql/m2m" },
+);
 
 app.get("/health", async () => ({ status: "ok", service: "exchange" }));
 
 await app.listen({ port: PORT, host: "0.0.0.0" });
 console.log(`Exchange server ready on port ${PORT}`);
 console.log("  /graphql - suppliers, products, quotes");
+console.log("  /graphql/m2m - pricing currency and locked conversions");

src/m2m-schema.ts

@@ -0,0 +1,193 @@
+import { GraphQLError } from 'graphql'
+
+import {
+  currencyRatesSnapshotForDate,
+  latestCurrencyRatesSnapshot,
+} from './currency-rate-store.js'
+import { convertMoney, currencyCode } from './currency-rates.js'
+import { prisma } from './db.js'
+
+type LockCurrencyPriceInput = {
+  sourceAmount: number
+  sourceCurrency: string
+  clientCurrency: string
+  pricingCountryCode: string
+  rateDate?: string | null
+}
+
+type ConvertCurrencyForDisplayInput = {
+  amount: number
+  sourceCurrency: string
+  displayCurrency: string
+}
+
+export const m2mTypeDefs = `#graphql
+  input LockCurrencyPriceInput {
+    sourceAmount: Float!
+    sourceCurrency: String!
+    clientCurrency: String!
+    pricingCountryCode: String!
+    rateDate: String
+  }
+
+  input ConvertCurrencyForDisplayInput {
+    amount: Float!
+    sourceCurrency: String!
+    displayCurrency: String!
+  }
+
+  type DisplayCurrencyConversion {
+    sourceAmount: Float!
+    sourceCurrency: String!
+    displayAmount: Float!
+    displayCurrency: String!
+    exchangeRate: Float!
+    rateSnapshotUuid: String
+    rateEffectiveDate: String!
+    rateQuotedAt: String!
+    provider: String!
+  }
+
+  type LockedCurrencyPrice {
+    sourceAmount: Float!
+    sourceCurrency: String!
+    clientAmount: Float!
+    clientCurrency: String!
+    exchangeRate: Float!
+    rateSnapshotUuid: String
+    rateEffectiveDate: String!
+    rateQuotedAt: String!
+    rateLockedAt: String!
+    provider: String!
+    attributionUrl: String
+    pricingCountryCode: String!
+  }
+
+  type Query {
+    health: String!
+    convertCurrencyForDisplay(input: ConvertCurrencyForDisplayInput!): DisplayCurrencyConversion!
+  }
+
+  type Mutation {
+    lockCurrencyPrice(input: LockCurrencyPriceInput!): LockedCurrencyPrice!
+  }
+`
+
+function countryCode(value: unknown): string {
+  const normalized = String(value ?? '').trim().toUpperCase()
+  if (!/^[A-Z]{2}$/.test(normalized)) {
+    throw new GraphQLError(`Invalid ISO 3166-1 country code: ${normalized || 'empty'}`)
+  }
+  return normalized
+}
+
+function historicalDate(value: string): Date {
+  if (!/^\d{4}-\d{2}-\d{2}$/.test(value)) {
+    throw new GraphQLError('rateDate must use YYYY-MM-DD format')
+  }
+  const result = new Date(`${value}T00:00:00.000Z`)
+  if (Number.isNaN(result.getTime()) || result.toISOString().slice(0, 10) !== value) {
+    throw new GraphQLError('rateDate is not a valid calendar date')
+  }
+  return result
+}
+
+async function lockCurrencyPrice(
+  _: unknown,
+  args: { input: LockCurrencyPriceInput },
+) {
+  const lockedAt = new Date()
+  const sourceAmount = Number(args.input.sourceAmount)
+  if (!Number.isFinite(sourceAmount) || sourceAmount < 0) {
+    throw new GraphQLError('sourceAmount must be a non-negative finite number')
+  }
+  const sourceCurrency = currencyCode(args.input.sourceCurrency)
+  const clientCurrency = currencyCode(args.input.clientCurrency)
+  const pricingCountryCode = countryCode(args.input.pricingCountryCode)
+  if (sourceCurrency === clientCurrency) {
+    const effectiveDate = args.input.rateDate
+      ? historicalDate(args.input.rateDate)
+      : lockedAt
+    return {
+      sourceAmount,
+      sourceCurrency,
+      clientAmount: sourceAmount,
+      clientCurrency,
+      exchangeRate: 1,
+      rateSnapshotUuid: null,
+      rateEffectiveDate: effectiveDate.toISOString().slice(0, 10),
+      rateQuotedAt: effectiveDate.toISOString(),
+      rateLockedAt: lockedAt.toISOString(),
+      provider: 'identity',
+      attributionUrl: null,
+      pricingCountryCode,
+    }
+  }
+  const snapshot = args.input.rateDate
+    ? await currencyRatesSnapshotForDate(historicalDate(args.input.rateDate))
+    : await latestCurrencyRatesSnapshot()
+  const exchangeRate = convertMoney(1, sourceCurrency, clientCurrency, snapshot)
+  return {
+    sourceAmount,
+    sourceCurrency,
+    clientAmount: sourceAmount * exchangeRate,
+    clientCurrency,
+    exchangeRate,
+    rateSnapshotUuid: snapshot.uuid,
+    rateEffectiveDate: snapshot.effectiveDate.toISOString().slice(0, 10),
+    rateQuotedAt: snapshot.updatedAt.toISOString(),
+    rateLockedAt: lockedAt.toISOString(),
+    provider: snapshot.provider,
+    attributionUrl: snapshot.attributionUrl,
+    pricingCountryCode,
+  }
+}
+
+async function convertCurrencyForDisplay(
+  _: unknown,
+  args: { input: ConvertCurrencyForDisplayInput },
+) {
+  const sourceAmount = Number(args.input.amount)
+  if (!Number.isFinite(sourceAmount) || sourceAmount < 0) {
+    throw new GraphQLError('amount must be a non-negative finite number')
+  }
+  const sourceCurrency = currencyCode(args.input.sourceCurrency)
+  const displayCurrency = currencyCode(args.input.displayCurrency)
+  if (sourceCurrency === displayCurrency) {
+    const quotedAt = new Date()
+    return {
+      sourceAmount,
+      sourceCurrency,
+      displayAmount: sourceAmount,
+      displayCurrency,
+      exchangeRate: 1,
+      rateSnapshotUuid: null,
+      rateEffectiveDate: quotedAt.toISOString().slice(0, 10),
+      rateQuotedAt: quotedAt.toISOString(),
+      provider: 'identity',
+    }
+  }
+  const snapshot = await latestCurrencyRatesSnapshot()
+  const exchangeRate = convertMoney(1, sourceCurrency, displayCurrency, snapshot)
+  return {
+    sourceAmount,
+    sourceCurrency,
+    displayAmount: sourceAmount * exchangeRate,
+    displayCurrency,
+    exchangeRate,
+    rateSnapshotUuid: snapshot.uuid,
+    rateEffectiveDate: snapshot.effectiveDate.toISOString().slice(0, 10),
+    rateQuotedAt: snapshot.updatedAt.toISOString(),
+    provider: snapshot.provider,
+  }
+}
+
+export const m2mResolvers = {
+  Query: {
+    health: () => 'ok',
+    convertCurrencyForDisplay,
+  },
+  Mutation: {
+    lockCurrencyPrice,
+  },
+}

src/schema.ts

@@ -1,5 +1,6 @@
 import { prisma } from './db.js'
 import { convertPrices, displayCurrency } from './currency-rates.js'
+import { latestCurrencyRatesSnapshot } from './currency-rate-store.js'
 
 type SupplierInput = {
   teamUuid?: string | null
@@ -37,6 +38,14 @@ type QuoteInput = {
   notes?: string | null
 }
 
+async function convertCatalogPrices<T extends { pricePerUnit: unknown; currency: string }>(
+  rows: T[],
+  displayCurrencyValue: unknown,
+) {
+  const snapshot = await latestCurrencyRatesSnapshot()
+  return convertPrices(rows, displayCurrencyValue, snapshot)
+}
+
 export const typeDefs = `#graphql
   type Supplier {
     uuid: ID!
@@ -200,7 +209,7 @@ async function productWithPriceSummaryFromProduct(
     select: { pricePerUnit: true, currency: true },
     take: 100,
   })
-  const convertedQuotes = await convertPrices(quotes, displayCurrencyValue)
+  const convertedQuotes = await convertCatalogPrices(quotes, displayCurrencyValue)
   const priceSeries = convertedQuotes.map(quote => quote.pricePerUnit).sort((a, b) => a - b)
   const averagePrice = priceSeries.length === 0
     ? null
@@ -366,7 +375,7 @@ export const resolvers = {
         orderBy: { createdAt: 'desc' },
       })
       return {
-        items: await convertPrices(quotes.slice(0, args.limit), rawArgs.displayCurrency),
+        items: await convertCatalogPrices(quotes.slice(0, args.limit), rawArgs.displayCurrency),
         offset: args.offset,
         limit: args.limit,
         hasMore: quotes.length > args.limit,
@@ -379,7 +388,7 @@ export const resolvers = {
         include: { supplier: true, product: true },
       })
       if (quote === null) return null
-      return (await convertPrices([quote], args.displayCurrency))[0]
+      return (await convertCatalogPrices([quote], args.displayCurrency))[0]
     },
   },