---
title: Queues guide
description: Background work with queues/*.ts producers and consumers — works on Outer today.
---

**Verdict: works.** Declare a queue file, send from anywhere, consume in
batches. Standard Cloudflare Queues under the hood — no extra service.

## 1. Declare the queue

One file per queue under `queues/`; the path sets the name
(`order/notifications.ts` → `order-notifications`):

```ts
// queues/emails.ts
import { defineQueue } from "void";

export default defineQueue<{ to: string; subject: string }>(async (batch, env) => {
  for (const msg of batch.messages) {
    await sendDigest(env, msg.body); // your function
    msg.ack();
  }
});

export const maxBatchSize = 50;
export const maxBatchTimeout = 10;
export const maxRetries = 5;
export const retryDelay = 30;
```

Only one consumer may read a queue. Un-acked messages ack on success and
retry on throw (first call wins); over `maxRetries` they are permanently
deleted — Void configures no dead-letter queue.

## 2. Produce

```ts
import { queues } from "void/queues";

await queues.emails.send({ to, subject }); // typed from defineQueue<T>
```

Batches cap at 100 messages / 256 KiB total, one message at 128 KiB.
Delivery is at-least-once and unordered — key work by the stable `msg.id`
and keep consumers idempotent. Retention is 4 days.

## 3. Deploy

Bindings come from the built `dist/wrangler.json`: `queues` is an accepted
deploy key (`crates/outer/src/deploy/pipeline.rs`), so the queue deploys on
every account — plan gating for bindings arrives with billing. Rebuild after
editing queue files; consumers deploy with the app and scale with it.

Trigger local dispatch manually with the dev server's `POST /__void/queue`
endpoint — queued messages don't run on their own.

## Sources

- Void queues guide: <https://void.cloud/guide/queues>
- Accepted wrangler keys: `crates/outer/src/deploy/pipeline.rs` (`ACCEPTED_CONFIG_KEYS`)
- celld queues: <https://celld.dev/docs/services/queues>