Add logic to detect when converting between a derived currency and its root currency, and apply the fixed mathematical factor directly (0.01 for GBp→GBP, 100 for GBP→GBp) instead of trying to fetch exchange rates.

apps/api/src/services/exchange-rate-data/exchange-rate-data.service.ts

@@ -270,6 +270,14 @@ export class ExchangeRateDataService {
 
     if (aFromCurrency === aToCurrency) {
       factor = 1;
+    } else {
+      const derivedCurrencyFactor = this.getDerivedCurrencyFactor(
+        aFromCurrency,
+        aToCurrency
+      );
+
+      if (derivedCurrencyFactor !== null) {
+        factor = derivedCurrencyFactor;
       } else {
         const dataSource =
           this.dataProviderService.getDataSourceForExchangeRates();
@@ -323,6 +331,7 @@ export class ExchangeRateDataService {
             marketPriceBaseCurrencyToCurrency;
         }
       }
+    }
 
     if (isNumber(factor) && !isNaN(factor)) {
       return factor * aValue;
@@ -357,7 +366,25 @@ export class ExchangeRateDataService {
       for (const date of dates) {
         factors[format(date, DATE_FORMAT)] = 1;
       }
-    } else {
+      return factors;
+    }
+
+    // Check if this is a conversion between a derived currency and its root currency
+    const derivedCurrencyFactor = this.getDerivedCurrencyFactor(
+      currencyFrom,
+      currencyTo
+    );
+
+    if (derivedCurrencyFactor !== null) {
+      // Use the fixed mathematical factor for derived currencies
+      for (const date of dates) {
+        factors[format(date, DATE_FORMAT)] = derivedCurrencyFactor;
+      }
+      return factors;
+    }
+
+    // Continue with standard exchange rate logic
+    {
       const dataSource =
         this.dataProviderService.getDataSourceForExchangeRates();
       const symbol = `${currencyFrom}${currencyTo}`;
@@ -469,6 +496,35 @@ export class ExchangeRateDataService {
     return factors;
   }
 
+  private getDerivedCurrencyFactor(
+    currencyFrom: string,
+    currencyTo: string
+  ): number | null {
+    // Check if currencyFrom is a derived currency of currencyTo
+    const derivedFrom = DERIVED_CURRENCIES.find(
+      ({ currency, rootCurrency }) =>
+        currency === currencyFrom && rootCurrency === currencyTo
+    );
+
+    if (derivedFrom) {
+      // e.g., GBp → GBP: factor = 1/100 = 0.01
+      return 1 / derivedFrom.factor;
+    }
+
+    // Check if currencyTo is a derived currency of currencyFrom
+    const derivedTo = DERIVED_CURRENCIES.find(
+      ({ currency, rootCurrency }) =>
+        currency === currencyTo && rootCurrency === currencyFrom
+    );
+
+    if (derivedTo) {
+      // e.g., GBP → GBp: factor = 100
+      return derivedTo.factor;
+    }
+
+    return null;
+  }
+
   private async prepareCurrencies(): Promise<string[]> {
     let currencies: string[] = [DEFAULT_CURRENCY];