Daily balance reconciliation against source-of-truth ledger

Without automated daily reconciliation, a discrepancy between the account balance table and the transaction ledger can persist indefinitely — and under SOX §404 that is a material weakness in internal controls over financial reporting. NIST 800-53 AU-2 requires that the organization identify events significant enough to warrant auditing; a mismatch between the authoritative ledger and running balances is exactly that event. FINRA Rule 4370 (Business Continuity Planning) requires that firms be able to reconstruct financial records. An ad-hoc or weekly reconciliation job means errors introduced by bugs, failed transactions, or double-credits can compound for days before detection, making remediation far more expensive and regulatorily exposed. A $0.01 tolerance threshold is the industry standard — anything larger conceals rounding errors that can be systematically exploited.

Add a cron job that runs every day at a fixed UTC time in src/jobs/reconciliation.ts:

import cron from 'node-cron';

async function reconcileBalances() {
  const accounts = await db('accounts').select('id', 'user_id', 'balance');
  for (const acct of accounts) {
    const { ledger_total } = await db('transaction_logs')
      .where({ user_id: acct.user_id })
      .sum('signed_amount as ledger_total')
      .first();
    const discrepancy = Math.abs(acct.balance - (ledger_total ?? 0));
    if (discrepancy > 0.01) {
      await db('reconciliation_issues').insert({
        account_id: acct.id, system_balance: acct.balance,
        ledger_balance: ledger_total, discrepancy,
        discovered_at: new Date()
      });
    }
  }
}

// Fires at 02:00 UTC every day
cron.schedule('0 2 * * *', reconcileBalances);

Persist each run's status to reconciliation_runs so the quarterly compliance assessment (see finserv-audit-trail.tamper-evidence.compliance-gap-assessment) can count failures.