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

# Delivery and reliability

> Understand background delivery, flushing, timeouts, retries, and circuit breaker behavior.

Lynx is designed so telemetry failures do not stop your AI service by default.

## Production defaults

| Option                            | Default         |
| --------------------------------- | --------------- |
| `delivery.mode`                   | `"BACKGROUND"`  |
| `delivery.timeoutMs`              | `1000`          |
| `delivery.flushOnRunEnd`          | `false`         |
| `delivery.flushIntervalMs`        | `3000`          |
| `delivery.batchSize`              | `50`            |
| `delivery.maxQueueSize`           | `1000`          |
| `delivery.overflowStrategy`       | `"DROP_OLDEST"` |
| `circuitBreaker.enabled`          | `true`          |
| `circuitBreaker.failureThreshold` | `3`             |
| `circuitBreaker.cooldownMs`       | `30000`         |

## Background delivery

In background mode, `run()` records events locally and returns without waiting for telemetry delivery. The SDK sends events from a timer, from explicit `flush()`, or from `shutdown()`.

```ts theme={null}
const lynx = new LynxTracer({
  clientId: "support-api",
  endpoint: "https://lynx.example.com",
  apiKey: process.env.LYNX_API_KEY,
  delivery: {
    mode: "BACKGROUND",
    timeoutMs: 1000,
    flushOnRunEnd: false,
  },
});
```

## Blocking delivery

Use blocking mode only when the current process must make a send attempt during the request lifecycle.

```ts theme={null}
const lynx = new LynxTracer({
  clientId: "worker",
  endpoint: "https://lynx.example.com",
  apiKey: process.env.LYNX_API_KEY,
  delivery: {
    mode: "BLOCKING",
    flushOnRunEnd: true,
    timeoutMs: 1500,
  },
});
```

## Flush and shutdown

```ts theme={null}
await lynx.flush();
```

Use `shutdown()` before the process exits.

```ts theme={null}
await lynx.shutdown({ timeoutMs: 1000 });
```

## Local status

```ts theme={null}
const status = lynx.getStatus();

console.log(status.queueSize);
console.log(status.circuitState);
console.log(status.droppedEvents);
```

## If the Lynx server is down

The SDK catches network, timeout, and non-2xx response errors. Failed batches move to an in-memory retry queue. After repeated failures, the circuit breaker opens and pauses delivery attempts until the cooldown passes.

If the queue reaches `maxQueueSize`, the SDK drops events according to `overflowStrategy`.