> ## 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: Preview Borrow operations

> Inspect the expected outcome and health impact of a Borrow operation before submitting a transaction

Preview a Borrow operation with its paired quote method, or size a borrow with
`getRequiredCollateral` or `getMaxBorrow`. For the full list of quote methods
and their return shapes, see
[Borrow quote methods](/app-kit/references/borrow-quote-methods).

## 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`.

## Preview a borrow

`getBorrowQuote` handles both opening a new loan and borrowing more against an
existing one. To preview opening a new loan, pass the `walletAddress`, `chain`,
and `marketId`:

```typescript TypeScript theme={null}
const quote = await kit.borrow.getBorrowQuote({
  chain: "Arc_Testnet",
  walletAddress: "0x...",
  marketId:
    "0x1111111111111111111111111111111111111111111111111111111111111111",
  borrowAmount: "1000.0",
});
```

To preview borrowing more against an existing loan, pass its `loanId`. The
service resolves the owner, blockchain, and market from the loan:

```typescript TypeScript theme={null}
const quote = await kit.borrow.getBorrowQuote({
  loanId: "11111111-1111-4111-8111-111111111111",
  borrowAmount: "500.0",
});
```

Either call returns the `collateralAmount` the borrow would pull, the
`loanAssetAmount` it would deliver, the market's `borrowApy`, `fees`, `gasFees`,
and the position's `resultingHealthFactor`, `resultingLtv`, `resultingBand`, and
`liquidationPrice`.

## Preview add collateral

Quote the effect of adding cirBTC to an existing loan:

```typescript TypeScript theme={null}
const quote = await kit.borrow.getAddCollateralQuote({
  chain: "Arc_Testnet",
  loanId: "11111111-1111-4111-8111-111111111111",
  collateralAmount: "0.05",
});
```

The quote returns `fees`, `gasFees`, and the position's resulting health fields
after the collateral addition.

## Preview a repayment

Quote a partial repayment. The SDK rejects repayments that exceed the loan's
outstanding debt at quote time.

```typescript TypeScript theme={null}
const quote = await kit.borrow.getRepayQuote({
  chain: "Arc_Testnet",
  loanId: "11111111-1111-4111-8111-111111111111",
  repayAmount: "100.0",
});
```

The quote returns the requested `repayAmount`, `fees`, `gasFees`, and resulting
health fields.

## Preview a full close

Quote a full payoff. Because `closeLoan` uses share-based payoff math and may
pull more USDC than needed (up to your `slippageBps` bound), the quote's
`bundledRepayment` reflects the upper bound of what the transaction may pull.

```typescript TypeScript theme={null}
const quote = await kit.borrow.getCloseLoanQuote({
  chain: "Arc_Testnet",
  loanId: "11111111-1111-4111-8111-111111111111",
});
```

The quote returns `bundledRepayment` (the upper bound of USDC the close may
pull), `collateralAmount` (the cirBTC returned), `fees`, `gasFees`, and
resulting health fields.

## Preview withdrawing collateral

Quote the effect of withdrawing collateral, including the USDC required for the
internal repay leg:

```typescript TypeScript theme={null}
const quote = await kit.borrow.getWithdrawCollateralRepayIfNeededQuote({
  chain: "Arc_Testnet",
  loanId: "11111111-1111-4111-8111-111111111111",
  collateralAmount: "0.01",
});
```

The quote returns `collateralAmount` (the cirBTC released), `bundledRepayment`
(the upper bound of USDC needed for the internal repay leg), `fees`, `gasFees`,
and resulting health fields.

Between preview and execution, the exact repayment amount can shift slightly as
interest accrues on the loan. `slippageBps` (default `300`, or 3%) caps how much
larger the actual repayment can be than the previewed amount. Pass a smaller
`slippageBps` to tighten the ceiling, or omit it for the default.

## Size a borrow

Use `getRequiredCollateral` when the user knows how much USDC they want and what
health factor they want to land on:

```typescript TypeScript theme={null}
const sizing = await kit.borrow.getRequiredCollateral({
  chain: "Arc_Testnet",
  marketId:
    "0x1111111111111111111111111111111111111111111111111111111111111111",
  borrowAmount: "1000.0",
  targetHealthFactor: 1.5,
});
```

Use `getMaxBorrow` when the user has a fixed collateral amount and wants to see
the largest borrow it supports:

```typescript TypeScript theme={null}
const ceiling = await kit.borrow.getMaxBorrow({
  chain: "Arc_Testnet",
  marketId:
    "0x1111111111111111111111111111111111111111111111111111111111111111",
  collateralAmount: "0.05",
});
```

Both return the sizing value along with `resultingHealthFactor` and
`liquidationPrice`. They do not return `fees`, `gasFees`, `resultingLtv`, or
`resultingBand`.