Events and delivery

Commands commit events. Consumers (views, policies, and projections) receive them later, when you call flush().

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

// Deliver pending events to policies and projections.
const [, deliveryError] = await bank.flush()
if (deliveryError !== null) throw deliveryError

The commit

A successful command saves the new state, its events, and a receipt in one step. The receipt describes the aggregate commit, not the success of every consumer.

Each event is wrapped in an envelope:

Field	Meaning
id	Stable event ID, e.g. ["Bank","Account","a-1"]:2. Use it as an idempotency key
stream	The source stream
seq	Sequence number within the stream
at	Timestamp (ms)
source	{ type, id } of the aggregate or view
event	The tagged event payload

Delivery

• flush() is explicit. There is no background worker or automatic backoff. Call flush() yourself (an atLeast read also flushes).
• Failures retry. A failed consumer stops that flush and keeps its checkpoint. The next flush() retries the unacknowledged delivery.
• At-least-once. Projection writes and policy actions must tolerate repeated delivery.
• Ordering is per source stream. There's no global ordering across sources.

WARNING

Don't await flush() from inside a consumer that is already running in that flush.

Who sees history

Consumer	Replays history?	Rebuild trigger
View	Yes	Bump version
Projection	Yes	Bump version
Policy	No, new events only	New policies start at the current position

Read your own writes

Views are eventually consistent. Pass the receipt to catch up first:

const [summary] = await bank.summary.get('a-1', { atLeast: receipt })

Without atLeast, you get whatever is materialized now, which may be null.