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

# Custom Environments

> Implement the Environment interface for your domain

## Python Interface

```python theme={null}
class MyEnv:
    def reset(self, goal: str) -> str:
        ...

    def step(self, action: str) -> tuple[str, bool, bool] | Awaitable[tuple[str, bool, bool]]:
        ...
```

Return value is `(observation, done, success)`.

## TypeScript Interface

```ts theme={null}
interface Environment {
  reset(goal: string): string | Promise<string>;
  step(action: string): StepResult | Promise<StepResult>;
}
```

Where:

```ts theme={null}
interface StepResult {
  observation: string;
  done: boolean;
  success: boolean;
}
```

## Practical Rules

1. Store the goal in `reset`.
2. Keep observation text actionable.
3. Terminate episodes via `done`.
4. Set `success` only on true goal completion.

## Reference Implementations

* Python file environment: `examples/file_api_env.py`
* Python coding environment: `examples/harbor_coding_agent.py`
* TypeScript demos: `icrl-ts/examples/*.ts`