levelops-sdk 0.1.0

# LevelOps Rust SDK

Ingest SLI events into LevelOps from any Rust application.

## Installation

Add to `Cargo.toml`:
```toml
[dependencies]
levelops-sdk = "0.1"
```

## Quickstart

```rust
use levelops_sdk::{Client, Config, Event};
use std::collections::HashMap;

#[tokio::main]
async fn main() {
    let client = Client::new(Config {
        api_key: "<tenant_key>".into(),
        sli_id:  "<uuid>".into(),
        ..Default::default()
    }).unwrap();

    let mut fields = HashMap::new();
    fields.insert("result".into(), "ok".into());
    fields.insert("latency_ms".into(), 120.into());

    client.record(Event { fields, ..Default::default() }).await.unwrap();
    client.flush().await.unwrap();
}
```

## Usage

### Direct record

```rust
// Auto-generated event_id
client.record(Event {
    fields:     [("result".into(), "ok".into()), ("latency_ms".into(), 120.into())].into(),
    dimensions: [("service".into(), "api".into())].into(),
    ..Default::default()
}).await?;

// Explicit event_id for idempotent retries
client.record(Event {
    event_id: Some("my-trace-id".into()),
    fields:   [("result".into(), "ok".into())].into(),
    ..Default::default()
}).await?;
```

### Measure (async closure)

```rust
// Auto-generated event_id
client.measure(|ctx| async move {
    // ... business logic ...
    ctx.set_result("ok");
    Ok(())
}, MeasureOpts::new([("service", "api")])).await?;

// Explicit event_id
client.measure(|ctx| async move {
    ctx.set_result("ok");
    Ok(())
}, MeasureOpts::new([("service", "api")]).event_id("my-trace-id")).await?;
```

## Configuration

| Field | Default | Description |
|---|---|---|
| `api_key` | — | Tenant API key (required) |
| `sli_id` | — | Target SLI UUID (required) |
| `base_url` | `https://api.levelops.io` | API base URL |
| `batch_size` | `100` | Flush after N events |
| `flush_interval` | `1s` | Flush every N duration |

## Behaviour

- `event_id` auto-generated (`Uuid::new_v4()`) per `record()` and per `measure()` closure exit. Override via `event_id`.
- `timestamp` auto-set to UTC now if not provided.
- Thread-safe buffer (`Mutex`) with background `tokio::spawn` flush task.
- Retries on HTTP 429 respecting `Retry-After` header (max 3 attempts, exponential backoff).
- Async-first API (`tokio`).