> ## Documentation Index
> Fetch the complete documentation index at: https://docs.korve.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Runtime SDK

> Publish queue messages, consume signed deliveries, and connect to managed caches.

`@korve-dev/sdk` is server-only. Korve injects a project-and-environment-scoped runtime token and
delivery secret; never substitute an organization API key or bundle the SDK into browser code.

```ts theme={null}
import { ack, createKorve, retry } from "@korve-dev/sdk";

const korve = createKorve();
const emails = korve.queue<{ userId: string }>("emails");
await emails.send({ userId: "u_123" }, { idempotencyKey: "welcome:u_123" });

export const POST = korve.handler<{ userId: string }>(async (message) => {
  await persistWelcomeEmailOnce(message.id, message.body.userId);
  return ack(); // or retry(30)
});
```

Queue delivery is at least once. Make durable effects idempotent with `message.id`; the SDK verifies
the timestamp and signature, but your application owns business-level deduplication. `sendBatch`
accepts up to 100 messages in one atomic request. `korve.cache("sessions")` returns the injected TLS
connection string for a ready cache.

See [Queues](/primitives/queues) and [Caches](/primitives/caches).