# Policies

Realtime API-key and subaccount-policy updates.

The Rust SDK intentionally exposes policy **streams only**. Unary policy administration requires a JWT/session and is not part of this API-key SDK.

| Method                                        | Event type         |
| --------------------------------------------- | ------------------ |
| `subscribe` / `subscribe_subaccount_policies` | `SubaccountPolicy` |
| `subscribe_api_policies`                      | `ApiPolicy`        |

```rust
let mut policies = client.policies.subscribe_api_policies(None).await?;
if let Some(policy) = policies.recv_result().await? {
    println!("{} {}", policy.policy_id, policy.revision);
}
if let Some(err) = policies.take_err() {
    eprintln!("policy stream ended: {err}");
}
```

`None` uses `Config.default_account_id`. Both private channels require API-key credentials plus Account ID and the corresponding policy read permission. The method returns only after private token fetch and the Centrifugo handshake.

Policy events may describe MFA requirements, but Rust cannot perform a browser MFA challenge. Manage mutations and assignments in the Polyester app/TypeScript session client.

## Related

- [API keys](https://testnet.polyester.com/docs/sdk/rust/reference/api-keys)
- [Authentication](https://testnet.polyester.com/docs/sdk/rust/guides/authentication)
- [Streaming](https://testnet.polyester.com/docs/sdk/rust/guides/streaming)