ensure pessimistic-lock writes run in a transaction for invoice processing

apps/edr-freight-api/src/modules/billing/billing.service.ts

@@ -825,6 +825,13 @@ export class BillingService {
     type?: string,
     manager?: EntityManager,
   ): Promise<Invoice | null> {
+    // Lookup can use the default manager (no lock). But the pessimistic-lock write
+    // inside `transition` NEEDS an open transaction: pass the caller's `manager`
+    // through untouched (undefined when there is no caller txn) so `runTransition`
+    // opens its own. Passing `this.dataSource.manager` here made `runTransition`
+    // treat it as an already-open transaction and skip wrapping — the lock then
+    // threw `An open transaction is required for pessimistic lock`, aborting the
+    // whole settle pass (the "reservations settle/reserve one at a time" symptom).
     const mg = manager ?? this.dataSource.manager;
     const invoice = await mg.findOne(Invoice, {
       where: {
@@ -842,7 +849,7 @@ export class BillingService {
       Freight.InvoiceStatus.Expired,
       "expired",
       {},
-      mg,
+      manager,
     );
   }