Schedule Nightly Reconciliation (Batch + Scheduled)

global class NightlyReconciliationJob implements Schedulable {
    global void execute(SchedulableContext sc) {
        Database.executeBatch(new RecalculateBalancesBatch(), 50);
    }
}

String cronExpr = '0 0 2 * * ?'; // 2:00 AM daily
System.schedule('Nightly Balance Reconciliation', cronExpr, new NightlyReconciliationJob());

This is Module 39's exact scheduled-batch shape, reused directly — a Schedulable class whose only job is to kick off Lesson 3's RecalculateBalancesBatch on a nightly cron schedule.

The trigger from Lesson 2 already keeps balances correct in real time for normal operations; this nightly job exists purely as Lesson 3's safety net. Running the full recalculation across every account constantly would be wasteful — a low-traffic overnight window is exactly when Module 41's "release management" thinking about low-risk timing applies just as well to batch jobs as it does to deployments.

Reconciliation is the general accounting practice of confirming two independently-derived numbers agree — here, the stored Balance__c against a freshly recalculated sum of Transaction__c history. A mismatch found and silently corrected by this nightly job is exactly the kind of drift Lesson 3 described, caught automatically rather than discovered by a customer noticing an incorrect balance.