refactor(OUT-3604): address PR #266 review nits

- invoice.service: simplify Undeposited-Funds ref to a ternary.
- payment.service: type paymentLines and build the fee line via
  push when feeTotal > 0 instead of a spread.
- webhook.service: accumulate gross/fee cents in a single reduce.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: SandipBajracharya

src/app/api/quickbooks/invoice/invoice.service.ts

@@ -950,19 +950,17 @@ export class InvoiceService extends BaseService {
 
     const intuitApi = new IntuitAPI(qbTokenInfo)
 
-    let depositToAccountRef: { value: string } | undefined
-    if (useBankDepositFlow) {
-      const undepositedFundsRef = await intuitApi.getUndepositedFundsAccountId()
-      depositToAccountRef = { value: undepositedFundsRef }
-    }
+    const depositToAccountRef = useBankDepositFlow
+      ? await intuitApi.getUndepositedFundsAccountId()
+      : undefined
 
     const qbPaymentPayload = {
       TotalAmt: invoiceAmount,
       CustomerRef: {
         value: existingCustomer.qbCustomerId,
       },
       ...(depositToAccountRef && {
-        DepositToAccountRef: depositToAccountRef,
+        DepositToAccountRef: { value: depositToAccountRef },
       }),
       Line: [
         {

src/app/api/quickbooks/payment/payment.service.ts

@@ -215,32 +215,35 @@ export class PaymentService extends BaseService {
       feeTotal: opts.feeTotal,
     })
 
-    const paymentLines = opts.lines.map((line) => ({
-      Amount: line.amount,
-      LinkedTxn: [
-        {
-          TxnId: line.qbPaymentId,
-          TxnType: 'Payment' as const,
-          TxnLineId: '0',
-        },
-      ],
-    }))
+    const paymentLines: Required<QBDepositCreatePayloadType>['Line'] =
+      opts.lines.map((line) => ({
+        Amount: line.amount,
+        LinkedTxn: [
+          {
+            TxnId: line.qbPaymentId,
+            TxnType: 'Payment' as const,
+            TxnLineId: '0',
+          },
+        ],
+      }))
 
-    const feeLine = {
-      Amount: -opts.feeTotal,
-      DetailType: 'DepositLineDetail' as const,
-      DepositLineDetail: {
-        AccountRef: { value: opts.expenseAccountRef },
-      },
-      Description: 'Stripe processing fees',
+    // feeTotal is always >= 0 (caller rejects negative): 0 = no fee line.
+    if (opts.feeTotal > 0) {
+      paymentLines.push({
+        Amount: -opts.feeTotal,
+        DetailType: 'DepositLineDetail' as const,
+        DepositLineDetail: {
+          AccountRef: { value: opts.expenseAccountRef },
+        },
+        Description: 'Stripe processing fees',
+      })
     }
 
     const depositPayload: QBDepositCreatePayloadType = {
       DepositToAccountRef: { value: opts.bankAccountRef },
       PrivateNote: opts.privateNote,
       TxnDate: opts.txnDate,
-      // feeTotal is always >= 0 (caller rejects negative): 0 = no fee line.
-      Line: opts.feeTotal > 0 ? [...paymentLines, feeLine] : paymentLines,
+      Line: paymentLines,
     }
 
     const parsedPayload = QBDepositCreatePayloadSchema.parse(depositPayload)

src/app/api/quickbooks/webhook/webhook.service.ts

@@ -628,8 +628,14 @@ export class WebhookService extends BaseService {
     }
 
     // Computed before the try so the FAILED-log path can record the amounts.
-    const grossCents = lineItems.reduce((sum, l) => sum + l.grossAmount, 0)
-    const feeCents = lineItems.reduce((sum, l) => sum + l.feeAmount, 0)
+    const { grossCents, feeCents } = lineItems.reduce(
+      (acc, line) => {
+        acc.grossCents += line.grossAmount
+        acc.feeCents += line.feeAmount
+        return acc
+      },
+      { grossCents: 0, feeCents: 0 },
+    )
 
     try {
       validateAccessToken(qbTokenInfo)