> ## Documentation Index
> Fetch the complete documentation index at: https://fhenix-docs-hardhat-3-plugin.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Client

> Create and connect a CofheClient inside a Hardhat 3 test

The plugin extends every Hardhat 3 connection with a `cofhe` namespace. There are three ways to create and connect a `CofheClient` from a test, in increasing order of control.

## Batteries included (recommended)

`cofhe.createClientWithBatteries(walletClient?)` is the one-call setup. It:

1. Creates a CoFHE config with `environment: 'hardhat'`.
2. Creates a `CofheClient`.
3. Connects it using the wallet client you pass (or the first wallet client on the connection if you don't).
4. Generates and signs a self permit so the client can immediately decrypt encrypted values.

```typescript theme={null}
import { describe, it } from 'node:test';
import { network } from 'hardhat';

describe('My FHE contract', async () => {
  const { viem, cofhe } = await network.connect();
  const [walletClient] = await viem.getWalletClients();

  it('decrypts a value', async () => {
    const client = await cofhe.createClientWithBatteries(walletClient);
    client.connected; // true
  });
});
```

Or call it with no arguments to use the first wallet client on the connection:

```typescript theme={null}
const client = await cofhe.createClientWithBatteries();
```

<Info>
  Because the self permit is created up-front, encrypt / decrypt / decryptForView / decryptForTx all work immediately without any additional setup.
</Info>

## Manual setup

For more control — custom config options, multiple signers, adjusting `encryptDelay` — set up the client step by step.

<Steps>
  <Step title="Create config">
    ```typescript theme={null}
    const config = await cofhe.createConfig();
    // With overrides:
    const config = await cofhe.createConfig({ mocks: { encryptDelay: 0 } });
    ```

    `cofhe.createConfig` wraps `createCofheConfig` from `@cofhe/sdk/node` with two Hardhat-3-specific additions:

    * Sets `environment: 'hardhat'` automatically.
    * Defaults `mocks.encryptDelay` to `0` so tests run without artificial wait times.
  </Step>

  <Step title="Create the client">
    ```typescript theme={null}
    const client = cofhe.createClient(config);
    ```

    The client is **not connected yet** — call `client.connect(...)` before using it.
  </Step>

  <Step title="Connect with the connection's wallet client">
    ```typescript theme={null}
    const publicClient = await viem.getPublicClient();
    const [walletClient] = await viem.getWalletClients();

    await client.connect(publicClient, walletClient);
    ```
  </Step>
</Steps>

## API summary

| Method                                           | Returns                | Description                                                                                                  |
| ------------------------------------------------ | ---------------------- | ------------------------------------------------------------------------------------------------------------ |
| `cofhe.createConfig(overrides?)`                 | `Promise<CofheConfig>` | CoFHE config pre-wired for the Hardhat mock environment (`environment: 'hardhat'`, `mocks.encryptDelay: 0`). |
| `cofhe.createClient(config)`                     | `CofheClient`          | Unconnected client. Call `client.connect(publicClient, walletClient)` before use.                            |
| `cofhe.createClientWithBatteries(walletClient?)` | `Promise<CofheClient>` | Fully configured + connected + self-permit signed. Defaults to the first wallet client on the connection.    |

## Using the client

Once connected, the client works identically to the standard SDK client. See:

* [Encrypting Inputs](/client-sdk/guides/encrypting-inputs)
* [Decrypt to View](/client-sdk/guides/decrypt-to-view)
* [Decrypt to Transact](/client-sdk/guides/decrypt-to-tx)
* [Permits](/client-sdk/guides/permits)