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

# Getting Started

> Set up @cofhe/hardhat-plugin for local FHE contract development and testing

`@cofhe/hardhat-plugin` extends Hardhat with everything you need to build and test FHE-enabled contracts locally — mock contracts, a pre-configured CoFHE client, and test utilities.

## What the plugin provides

* **Mock contracts** deployed automatically on every `npx hardhat test` / `npx hardhat node` run, simulating the full CoFHE coprocessor stack on the Hardhat network.
* **`hre.cofhe`** — a namespaced API for creating and connecting CoFHE clients with Hardhat signers.
* **`hre.cofhe.mocks`** — utilities for reading raw plaintext values and interacting with mock contracts directly in tests.
* **Pre-configured networks** — `localcofhe`, `eth-sepolia`, and `arb-sepolia` are injected automatically.

## Installation

<Steps>
  <Step title="Install the package">
    <CodeGroup>
      ```bash npm theme={null}
      npm install @cofhe/hardhat-plugin @cofhe/sdk @cofhe/mock-contracts @fhenixprotocol/cofhe-contracts
      ```

      ```bash pnpm theme={null}
      pnpm add @cofhe/hardhat-plugin @cofhe/sdk @cofhe/mock-contracts @fhenixprotocol/cofhe-contracts
      ```

      ```bash yarn theme={null}
      yarn add @cofhe/hardhat-plugin @cofhe/sdk @cofhe/mock-contracts @fhenixprotocol/cofhe-contracts
      ```
    </CodeGroup>
  </Step>

  <Step title="Import in your Hardhat config">
    ```typescript hardhat.config.ts theme={null}
    import '@cofhe/hardhat-plugin';

    export default {
      solidity: '0.8.28',
    };
    ```

    That's it. The plugin automatically deploys the mock contracts before every test run.
  </Step>
</Steps>

## Configuration

The plugin adds an optional `cofhe` key to your Hardhat config:

```typescript hardhat.config.ts theme={null}
import '@cofhe/hardhat-plugin';

export default {
  solidity: '0.8.28',
  cofhe: {
    logMocks: true,    // log FHE ops to the console (default: true)
    gasWarning: true,  // warn when mock gas usage is high (default: true)
  },
};
```

## Pre-configured networks

The following networks are injected automatically. You can override any of them by defining the same key under `networks` in your config.

| Network       | URL                         | Chain ID   |
| ------------- | --------------------------- | ---------- |
| `localcofhe`  | `http://127.0.0.1:42069`    | —          |
| `eth-sepolia` | Ethereum Sepolia public RPC | `11155111` |
| `arb-sepolia` | Arbitrum Sepolia public RPC | `421614`   |

For testnets, set `PRIVATE_KEY` (and optionally `SEPOLIA_RPC_URL` / `ARBITRUM_SEPOLIA_RPC_URL`) in your environment.

## Auto-deployment

Mock contracts are deployed automatically before:

* `npx hardhat test`
* `npx hardhat node`

To skip auto-deployment (e.g., when running tests only against an external RPC):

```bash theme={null}
COFHE_SKIP_MOCKS_DEPLOY=1 npx hardhat test
```

## Next steps

* [Client](/client-sdk/hardhat-plugin/client) — create and connect a CoFHE client in tests.
* [Mock Contracts](/client-sdk/hardhat-plugin/mock-contracts) — read plaintext values and interact with mock contracts.
* [Logging](/client-sdk/hardhat-plugin/logging) — inspect FHE operations in test output.
* [Testing](/client-sdk/hardhat-plugin/testing) — end-to-end test patterns.