The automation is the code. The code is the diagram.

// Activities do the real work — I/O, compute, retries
/** @retry 3  @backoff exponential */
async function fetchInvoices(since: string): Promise<Invoice[]> { … }
async function enrich(inv: Invoice): Promise<Entry> { … }
async function buildReport(entries: Entry[]): Promise<Report> { … }
async function postToLedger(r: Report): Promise<void> { … }

// The root only directs — order, fan-out, waits
export default async function main() {
  const invoices = await fetchInvoices('yesterday')

  // parallel fan-out, one durable checkpoint per item
  const entries = await fp.parallel(...invoices.map(i => enrich(i)))
  const report = await buildReport(entries)

  // pauses here — survives restarts, resumes with input
  const { approved } = await fp.waitForSignal('approve')
  if (approved) {
    await postToLedger(report)
  }
}