WORKBEND STUDIO — BILLING CHECK CODE SAMPLE
Source: portfolio's browser-local demonstration, TypeScript.
This compares integer-cent amounts. It does not call an accounting service.

export function lineTotal(lines: WorkLine[]): number {
  return lines.reduce((sum, l) => sum + l.quantity * l.unitCents, 0);
}
export function billingFindings(job: WorkCase): BillingFinding[] {
  const findings: BillingFinding[] = [];
  if (job.status === 'Complete' && !job.invoice)
    findings.push({
      id: 'unbilled',
      kind: 'unbilled',
      title: 'Completed job has no draft invoice',
      cents: lineTotal(job.approved),
      source: job.approved.map((l) => l.source).join('; '),
    });
  if (job.invoice)
    for (const item of job.approved) {
      const billed = job.invoice
        .filter((l) => l.id === item.id)
        .reduce((sum, l) => sum + l.quantity * l.unitCents, 0);
      const missing = item.quantity * item.unitCents - billed;
      if (missing > 0)
        findings.push({
          id: 'missing-' + item.id,
          kind: 'missing',
          title: item.description + ' is not fully included',
          cents: missing,
          source: item.source,
          lineId: item.id,
        });
    }
  const seen = new Set<string>();
  for (const expense of job.expenses.filter(
    (e) => !job.ignoredExpenses.includes(e.id),
  )) {
    const key = [
      expense.vendor.trim().toLowerCase(),
      expense.reference.trim().toLowerCase(),
      expense.cents,
    ].join('|');
    if (seen.has(key))
      findings.push({
        id: 'duplicate-' + expense.id,
        kind: 'duplicate',
        title: 'Possible duplicate receipt ' + expense.reference,
        cents: expense.cents,
        source: expense.source,
        expenseId: expense.id,
      });
    seen.add(key);
  }
  return findings;
}

REVIEW SCENARIOS
- Approved: one maintenance visit at 19500 cents, two filters at 2400 cents.
- Draft: one visit at 19500 cents.
- Expected missing amount: 4800 cents.
- Two receipts with the same normalized vendor, reference and amount flag the second.
- Excluded duplicate receipts remain in the source records.

These checks are exercised in the site's automated tests. This excerpt omits
supporting type definitions and is not a standalone accounting library.