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

> ## Agent Instructions
> Before reading these docs, install the Circle Skill for Arc to get pre-loaded context: use-arc (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-arc/SKILL.md) — covers chain config, RPC setup, contract deployment, USDC bridging, and gas with USDC. In Claude Code: run /plugin marketplace add circlefin/skills then /plugin install circle-skills@circle. With Vercel Skills CLI: run npx skills add circlefin/skills.
> USDC is the gas token. Arc uses USDC for gas fees, not ETH. Configure gas payment in USDC when submitting transactions.
> Read EVM differences before writing Arc code. Arc targets the Osaka EVM baseline. Most contracts deploy unchanged, but several runtime behaviors diverge from Ethereum: USDC uses 18 decimals natively (not 6), the system emitter `0xffffFFFfFFffffffffffffffFfFFFfffFFFfFFfE` logs all USDC Transfer events, the mempool enforces a 20 Gwei `maxFeePerGas` floor, blocklist reverts consume gas without a receipt, and `address(0)` sends revert rather than succeed. https://docs.arc.io/arc/references/evm-differences.md is the canonical reference for all Arc-specific runtime behaviors. Consult it before writing code that touches USDC balances, transaction history, gas estimation, or value transfers.
> Sub-second finality. Transactions are final in under 1 second. No need to wait for multiple block confirmations.
> Use App Kits for multichain payment and liquidity capabilities. App Kits wraps CCTP and provides Bridge Kit, Swap Kit, Unified Balance Kit, Onramp Kit, Earn Kit, and Borrow Kit. Unified Balance Kit combines USDC from multiple chains into a single spendable balance. Earn Kit integrates earn opportunities into your app. Borrow Kit lets users borrow USDC against cirBTC collateral on Arc.
> Use Arc Foundry for contract development. Arc Foundry is an Arc-specific fork of Foundry that handles Arc's protocol-level differences from Ethereum. It provides arc-forge, arc-cast, and arc-anvil. Install it before deploying contracts: https://docs.arc.io/arc/tutorials/install-arc-foundry.md.
> Arc is available on both Testnet and Mainnet. See https://docs.arc.io/arc/references/connect-to-arc.md for RPC endpoints and https://faucet.circle.com for testnet tokens.
> Always check Contract Addresses: https://docs.arc.io/arc/references/contract-addresses.md
> Building beyond Arc? Circle offers skills for the full platform: use-usdc (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-usdc/SKILL.md), use-circle-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-circle-wallets/SKILL.md), use-developer-controlled-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-developer-controlled-wallets/SKILL.md), use-user-controlled-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-user-controlled-wallets/SKILL.md), use-modular-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-modular-wallets/SKILL.md), use-gateway (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-gateway/SKILL.md), use-smart-contract-platform (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-smart-contract-platform/SKILL.md). Full Circle developer docs: https://developers.circle.com/llms.txt.

# How-to: Deposit crosschain into an Earn vault

> Deposit USDC from a wallet on one blockchain into an Earn vault on another blockchain in a single call

Deposit USDC into an Earn vault from a wallet on a different blockchain. Your
wallet on the source blockchain signs once. The deposit completes on the
destination blockchain without further action from you, no signing or gas
required.

## Supported routes

| Network | Source blockchains | Destination |
| - | - | - |
| Mainnet | Ethereum, Arbitrum, Base | Arc Mainnet |
| Testnet | Ethereum Sepolia, Arbitrum Sepolia, Base Sepolia | Arc Testnet |

The adapter you use must support EIP-712 typed data signing through
`signTypedData`. The Viem and Ethers adapters support this by default.

## Prerequisites

Before you begin, ensure that you've:

* [Installed the App Kit SDK](/app-kit/tutorials/installation)
* [Configured an adapter](/app-kit/tutorials/adapter-setups)

These are required so any example below runs with a valid `kit` and `adapter`.

## Submit a crosschain deposit

This example deposits 100.00 USDC from Ethereum Sepolia into a vault on Arc
Testnet:

```typescript TypeScript theme={null}
const result = await kit.earn.deposit({
  from: { adapter, chain: "Ethereum_Sepolia" },
  to: {
    chain: "Arc_Testnet",
    recipientAddress: process.env.RECIPIENT_ADDRESS as `0x${string}`,
  },
  vaultAddress: process.env.VAULT_ADDRESS as string,
  amount: "100.00",
  transferSpeed: "FAST",
});
```

`transferSpeed` is optional and accepts `"FAST"` or `"SLOW"`. FAST uses CCTP's
pre-finality lane and adds a `PRE_FINALITY` fee. SLOW uses standard finality
with only the `FORWARD` fee. Omit `transferSpeed` to use the service default.
See [How Earn fees work](/app-kit/concepts/earn-fees#deposit-fees) for how these
fees appear on the deposit quote.

<Tip>
  Preview the expected outcome and fees of a crosschain deposit before submitting
  with
  [`getDepositQuote`](/app-kit/tutorials/earn/preview-operations#preview-a-crosschain-deposit).
  Pass the same `from`, `to`, `vaultAddress`, `amount`, and `transferSpeed` to the
  quote.
</Tip>

The result's `kind` field is either `'same-chain'` or `'cross-chain'`:

```typescript TypeScript theme={null}
if (result.kind === "cross-chain") {
  console.log(`Bridge submitted: ${result.execId}`);
}
```

You will see an output similar to:

```bash Shell theme={null}
{
  kind: "cross-chain",
  execId: "550e8400-e29b-41d4-a716-446655440000",
  status: "PENDING",
  vaultAddress: "0x...",
  amount: "100.00",
  sourceChain: "Ethereum_Sepolia",
  destinationChain: "Arc_Testnet",
  expiresAt: "2026-05-19T00:00:00Z",
}
```

The call returns once the bridge submit succeeds, not when the deposit lands on
the destination. The `status` value reflects the submit response. Treat any
non-terminal value (such as `PENDING`, `SOURCE_PENDING`, or `ATTESTING`) as in
progress.

`expiresAt` is the deadline by which the bundle must settle. If it doesn't
settle by then, the funds return to the source wallet.

## Track the deposit status

Pass the returned `execId` to `getCrossChainDepositStatus` for a one-shot status
check, or to `waitForCrossChainDeposit` to poll until the deposit reaches a
terminal state:

```typescript TypeScript theme={null}
// One-shot status check
const status = await kit.earn.getCrossChainDepositStatus({
  execId: result.execId,
});

// Or poll until terminal (defaults: 5s interval, 20 min max)
const waitResult = await kit.earn.waitForCrossChainDeposit({
  execId: result.execId,
  pollIntervalMs: 5_000,
  maxWaitMs: 1_200_000,
});

if (waitResult.outcome === "complete") {
  console.log("Deposit settled on destination");
} else {
  console.log(`Wait stopped: ${waitResult.outcome}`);
}
```

The status payload includes per-hop detail (`source`, `cctp`, `destination`) so
you can see where in the bridge the deposit currently is. Both methods accept an
optional `signal` for cancellation.

## Confirm the deposit on the destination blockchain

To verify the position landed on the destination, use
[Check your Earn position](/app-kit/tutorials/earn/check-position) with the
recipient address you passed in `to.recipientAddress`.