# Pay gas in any token

Users don't need native ETH at all — they can pay gas in any **ERC-20**. The user
signs an exact fee; the on-chain `KryardDelegate` transfers that token amount to the
relayer as the batch's final step.

## How it works

1. Kryard quotes a token fee off-chain (`gas × price × rate × margin`).
2. The user signs the batch **including** the exact `gasToken` + `gasTokenAmount` —
   so the relayer can never inflate it.
3. `KryardDelegate.executeWithGasReimbursement` runs the batch, then transfers the
   token fee to the relayer and emits `GasReimbursed(relayer, gasToken, amount)`.
4. Kryard records the token usage; query it via [`token_usage`](/api/relay-routes).

## Usage

Add `gasToken`, `gasTokenAmount`, and `relayer` to `sponsorExecute`:

```ts
await sponsorExecute({
  client, signer, chainId, signWith, delegateAddress, calls, nonce,
  gasToken: USDC,
  gasTokenAmount: 50_000n,   // Kryard quotes this off-chain
  relayer: RELAYER_ADDRESS,  // the address the relayer signs with on this chain
});
```

::: warning The user signs the fee
The fee is part of the digest the user signs — it is cryptographically fixed. A
relayer cannot charge more than the user agreed to. The user must hold enough of
`gasToken` and have approved the delegate to move it where required.
:::

## Verifying settlement

The reimbursement is observable two ways:

- **On-chain:** the `GasReimbursed` event on the transaction.
- **Off-chain:** the org's [`token_usage`](/api/relay-routes) rollup reflects the
  `gas_token` / `gas_token_amount` recorded for the activity.