fix: count brokerage cash once and skip short-position return percent (WealthLedger/backend#140)

src/modules/investments/brokerage-accounts/brokerage-accounts.service.spec.ts

@@ -128,6 +128,27 @@ describe('saved brokerage account projection', () => {
     });
   });
 
+  it('omits return percent for a currency with short positions', async () => {
+    portfolio.saved.mockResolvedValueOnce({
+      membership: meta,
+      accounts: [{
+        id: 'a', name: 'A', type: 'BROKERAGE', openedOn: null, meta,
+        snapshot: {
+          cashBalances: [], structure: {}, totalsByCurrency: [],
+          positions: [
+            { type: 'STOCK', quantity: '-2', averagePurchasePrice: { currency: 'RUB', value: '100' }, absoluteReturn: { currency: 'RUB', value: '-20' } },
+            { type: 'STOCK', quantity: '1', averagePurchasePrice: { currency: 'USD', value: '10' }, absoluteReturn: { currency: 'USD', value: '1' } },
+          ],
+        },
+      }],
+    });
+
+    expect((await service.list('owner')).data?.[0]?.portfolioSummary?.unrealizedReturnByCurrency).toEqual([
+      { currency: 'RUB', absolute: '-20', costBasis: '-200', percent: null, partial: false },
+      { currency: 'USD', absolute: '1', costBasis: '10', percent: '10', partial: false },
+    ]);
+  });
+
   it('observes the latest hourly walk without starting another one', async () => {
     portfolio.saved.mockResolvedValue({ membership: meta, accounts: [] });
     sync.hourly.mockResolvedValue({

src/modules/investments/brokerage-accounts/brokerage-accounts.service.ts

@@ -19,6 +19,7 @@ import {
 } from './brokerage-account.dto';
 
 const PERCENT_DECIMAL_PLACES = 2;
+const ZERO_QUANTITY = 0n;
 
 function unrealizedReturns(positions: PortfolioPositionDto[]): UnrealizedReturnDto[] {
   // Cash-like CURRENCY positions must not duplicate the separately returned cash balances.
@@ -47,6 +48,13 @@ function unrealizedReturns(positions: PortfolioPositionDto[]): UnrealizedReturnD
       return money ? [money.currency] : [];
     }),
   );
+  // A short position has negative cost basis, so a percent would flip sign or net out.
+  const withShorts = new Set(
+    investments.flatMap((position) => {
+      const money = position.absoluteReturn ?? position.averagePurchasePrice ?? position.currentValue;
+      return money && decimalFromString(position.quantity).value < ZERO_QUANTITY ? [money.currency] : [];
+    }),
+  );
   const currencies = new Set([...absolute, ...costs].map((money) => money.currency));
   return [...new Set([...currencies, ...partial])]
     .sort((left, right) => left.localeCompare(right))
@@ -58,7 +66,7 @@ function unrealizedReturns(positions: PortfolioPositionDto[]): UnrealizedReturnD
         currency,
         absolute: absoluteReturn,
         costBasis,
-        percent: isZero(cost)
+        percent: isZero(cost) || withShorts.has(currency)
           ? null
           : formatDecimal(divide(
               multiply(decimalFromString(absoluteReturn), decimalFromString('100')),