> ## Documentation Index
> Fetch the complete documentation index at: https://arkor-92aeef0e-eng-615.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Trainer control

> Drive a run from your own code: start, wait, cancel.

# Trainer control

The `Trainer` returned by [`createTrainer`](/guides/sdk/create-trainer) has three methods: `start`, `wait`, `cancel`. `arkor start` and Studio's **Run training** button call `start()` followed by `wait()` for you. You only call them yourself when wiring training into your own code (a server, a script, a custom CLI).

```ts theme={null}
const { jobId } = await trainer.start();
const { artifacts } = await trainer.wait();
```

* `start()` submits the job and resolves once the backend accepts it.
* `wait()` opens the SSE event stream, dispatches your callbacks, and resolves when the run finishes.
* `cancel()` asks the backend to stop the run.

If you only need callbacks, you do not need to handle `start` / `wait` directly: `arkor start` does it. Reach for these methods when you are running outside the CLI.

## Stopping a wait early

Pass an `abortSignal` to `createTrainer` if you need a way to stop your local `wait()` loop without waiting for the backend:

```ts theme={null}
const controller = new AbortController();

const trainer = createTrainer({
  /* ... */
  abortSignal: controller.signal,
});

// from somewhere else:
controller.abort();
```

`abortSignal` only stops your local loop. To also stop the GPU on the backend, call `await trainer.cancel()` afterwards.

## Reference

For the exact reject vs resolve behavior, the SSE reconnect rules (`initialReconnectDelayMs`, `maxReconnectDelayMs`, `maxReconnectAttempts`), the idempotency guarantee on `start()`, and the full two-process pattern with `SIGINT` handling, see the [Trainer control reference](/sdk/trainer-control).