Notifications + SQLite ledger

Open an account, deposit money, record a ledger entry in SQLite, and ask an external notification system to tell the account holder. The domain only knows two contracts: Notifications.send and LedgerStore.record.

Source: notifications/

Run it

npm run notifications
npm run notifications:effect

Each prints the mode, a committed balance of 100, one ledger row, and Notifications sent: 1. The runner starts a dummy notification service on a loopback port. No public service or account needed.

Pass a fresh filename to inspect the ledger afterwards:

npm run notifications -- /tmp/accord-pure.sqlite

The flow

const [, openError] = await bank.account.open('a-1')
if (openError !== null) throw openError

const [receipt, error] = await bank.account.deposit('a-1', 100)
if (error !== null) throw error
console.log(receipt.reply.balance) // 100

const [, deliveryError] = await bank.flush()
if (deliveryError !== null) throw deliveryError

1. A method updates state and emits Opened or Deposited. State and events commit together.
2. flush() delivers events to the ledger projection and the notification policy.
3. The policy uses the envelope's stable event ID as the notification's idempotency key.

Swap in a fake

const notifications: NotificationPort = {
  async send(input) {
    console.log('Notification requested:', input.accountId)
    return ok({ id: `fake-${input.eventId}` })
  },
}

const { bank } = createBank(ledger, notifications)

Adapters

• The HTTP adapters send the event ID as an idempotency key, validate acknowledgements, time out after five seconds, and forward cancellation.
• Conflicts become NotificationConflict; failed responses become NotificationsUnavailable; network and decoding failures become Unexpected.
• The SQLite adapter upserts by event ID, so replays are safe. A failed statement rolls back the whole batch.

WARNING

The default runner persists the ledger only. Aggregate state and checkpoints stay in memory. For durable state, pass a SQLite runtime store and share its connection with the ledger:

using storage = sqlite('bank.sqlite')
using ledger = openLedger(storage.database)
const { bank } = createBank(ledger, notifications, storage)

Files

File	Responsibility
domain.ts	Account, rejections, external system contracts
pure.ts	Native projection, policy, and model
with-effect.ts	Effect projection, policy, and model
adapters/notifications.ts	Native notification adapter
adapters/notifications-effect.ts	Effect notification adapter
adapters/dummy-notifications.ts	Dummy notification service
adapters/sqlite.ts	SQLite ledger
run.ts	Binds adapters, wires the model, runs it